diff options
Diffstat (limited to 'fs/namei.c')
| -rw-r--r-- | fs/namei.c | 4552 |
1 files changed, 4552 insertions, 0 deletions
diff --git a/fs/namei.c b/fs/namei.c new file mode 100644 index 000000000..fe30d3be4 --- /dev/null +++ b/fs/namei.c @@ -0,0 +1,4552 @@ +/* + * linux/fs/namei.c + * + * Copyright (C) 1991, 1992 Linus Torvalds + */ + +/* + * Some corrections by tytso. + */ + +/* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname + * lookup logic. + */ +/* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. + */ + +#include <linux/init.h> +#include <linux/export.h> +#include <linux/kernel.h> +#include <linux/slab.h> +#include <linux/fs.h> +#include <linux/namei.h> +#include <linux/pagemap.h> +#include <linux/fsnotify.h> +#include <linux/personality.h> +#include <linux/security.h> +#include <linux/ima.h> +#include <linux/syscalls.h> +#include <linux/mount.h> +#include <linux/audit.h> +#include <linux/capability.h> +#include <linux/file.h> +#include <linux/fcntl.h> +#include <linux/device_cgroup.h> +#include <linux/fs_struct.h> +#include <linux/posix_acl.h> +#include <linux/hash.h> +#include <asm/uaccess.h> + +#include "internal.h" +#include "mount.h" + +/* [Feb-1997 T. Schoebel-Theuer] + * Fundamental changes in the pathname lookup mechanisms (namei) + * were necessary because of omirr. The reason is that omirr needs + * to know the _real_ pathname, not the user-supplied one, in case + * of symlinks (and also when transname replacements occur). + * + * The new code replaces the old recursive symlink resolution with + * an iterative one (in case of non-nested symlink chains). It does + * this with calls to <fs>_follow_link(). + * As a side effect, dir_namei(), _namei() and follow_link() are now + * replaced with a single function lookup_dentry() that can handle all + * the special cases of the former code. + * + * With the new dcache, the pathname is stored at each inode, at least as + * long as the refcount of the inode is positive. As a side effect, the + * size of the dcache depends on the inode cache and thus is dynamic. + * + * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink + * resolution to correspond with current state of the code. + * + * Note that the symlink resolution is not *completely* iterative. + * There is still a significant amount of tail- and mid- recursion in + * the algorithm. Also, note that <fs>_readlink() is not used in + * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() + * may return different results than <fs>_follow_link(). Many virtual + * filesystems (including /proc) exhibit this behavior. + */ + +/* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: + * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL + * and the name already exists in form of a symlink, try to create the new + * name indicated by the symlink. The old code always complained that the + * name already exists, due to not following the symlink even if its target + * is nonexistent. The new semantics affects also mknod() and link() when + * the name is a symlink pointing to a non-existent name. + * + * I don't know which semantics is the right one, since I have no access + * to standards. But I found by trial that HP-UX 9.0 has the full "new" + * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the + * "old" one. Personally, I think the new semantics is much more logical. + * Note that "ln old new" where "new" is a symlink pointing to a non-existing + * file does succeed in both HP-UX and SunOs, but not in Solaris + * and in the old Linux semantics. + */ + +/* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink + * semantics. See the comments in "open_namei" and "do_link" below. + * + * [10-Sep-98 Alan Modra] Another symlink change. + */ + +/* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: + * inside the path - always follow. + * in the last component in creation/removal/renaming - never follow. + * if LOOKUP_FOLLOW passed - follow. + * if the pathname has trailing slashes - follow. + * otherwise - don't follow. + * (applied in that order). + * + * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT + * restored for 2.4. This is the last surviving part of old 4.2BSD bug. + * During the 2.4 we need to fix the userland stuff depending on it - + * hopefully we will be able to get rid of that wart in 2.5. So far only + * XEmacs seems to be relying on it... + */ +/* + * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) + * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives + * any extra contention... + */ + +/* In order to reduce some races, while at the same time doing additional + * checking and hopefully speeding things up, we copy filenames to the + * kernel data space before using them.. + * + * POSIX.1 2.4: an empty pathname is invalid (ENOENT). + * PATH_MAX includes the nul terminator --RR. + */ + +#define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname)) + +struct filename * +getname_flags(const char __user *filename, int flags, int *empty) +{ + struct filename *result; + char *kname; + int len; + + result = audit_reusename(filename); + if (result) + return result; + + result = __getname(); + if (unlikely(!result)) + return ERR_PTR(-ENOMEM); + + /* + * First, try to embed the struct filename inside the names_cache + * allocation + */ + kname = (char *)result->iname; + result->name = kname; + + len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX); + if (unlikely(len < 0)) { + __putname(result); + return ERR_PTR(len); + } + + /* + * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a + * separate struct filename so we can dedicate the entire + * names_cache allocation for the pathname, and re-do the copy from + * userland. + */ + if (unlikely(len == EMBEDDED_NAME_MAX)) { + const size_t size = offsetof(struct filename, iname[1]); + kname = (char *)result; + + /* + * size is chosen that way we to guarantee that + * result->iname[0] is within the same object and that + * kname can't be equal to result->iname, no matter what. + */ + result = kzalloc(size, GFP_KERNEL); + if (unlikely(!result)) { + __putname(kname); + return ERR_PTR(-ENOMEM); + } + result->name = kname; + len = strncpy_from_user(kname, filename, PATH_MAX); + if (unlikely(len < 0)) { + __putname(kname); + kfree(result); + return ERR_PTR(len); + } + if (unlikely(len == PATH_MAX)) { + __putname(kname); + kfree(result); + return ERR_PTR(-ENAMETOOLONG); + } + } + + result->refcnt = 1; + /* The empty path is special. */ + if (unlikely(!len)) { + if (empty) + *empty = 1; + if (!(flags & LOOKUP_EMPTY)) { + putname(result); + return ERR_PTR(-ENOENT); + } + } + + result->uptr = filename; + result->aname = NULL; + audit_getname(result); + return result; +} + +struct filename * +getname(const char __user * filename) +{ + return getname_flags(filename, 0, NULL); +} + +struct filename * +getname_kernel(const char * filename) +{ + struct filename *result; + int len = strlen(filename) + 1; + + result = __getname(); + if (unlikely(!result)) + return ERR_PTR(-ENOMEM); + + if (len <= EMBEDDED_NAME_MAX) { + result->name = (char *)result->iname; + } else if (len <= PATH_MAX) { + struct filename *tmp; + + tmp = kmalloc(sizeof(*tmp), GFP_KERNEL); + if (unlikely(!tmp)) { + __putname(result); + return ERR_PTR(-ENOMEM); + } + tmp->name = (char *)result; + result = tmp; + } else { + __putname(result); + return ERR_PTR(-ENAMETOOLONG); + } + memcpy((char *)result->name, filename, len); + result->uptr = NULL; + result->aname = NULL; + result->refcnt = 1; + audit_getname(result); + + return result; +} + +void putname(struct filename *name) +{ + BUG_ON(name->refcnt <= 0); + + if (--name->refcnt > 0) + return; + + if (name->name != name->iname) { + __putname(name->name); + kfree(name); + } else + __putname(name); +} + +static int check_acl(struct inode *inode, int mask) +{ +#ifdef CONFIG_FS_POSIX_ACL + struct posix_acl *acl; + + if (mask & MAY_NOT_BLOCK) { + acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); + if (!acl) + return -EAGAIN; + /* no ->get_acl() calls in RCU mode... */ + if (acl == ACL_NOT_CACHED) + return -ECHILD; + return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); + } + + acl = get_acl(inode, ACL_TYPE_ACCESS); + if (IS_ERR(acl)) + return PTR_ERR(acl); + if (acl) { + int error = posix_acl_permission(inode, acl, mask); + posix_acl_release(acl); + return error; + } +#endif + + return -EAGAIN; +} + +/* + * This does the basic permission checking + */ +static int acl_permission_check(struct inode *inode, int mask) +{ + unsigned int mode = inode->i_mode; + + if (likely(uid_eq(current_fsuid(), inode->i_uid))) + mode >>= 6; + else { + if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { + int error = check_acl(inode, mask); + if (error != -EAGAIN) + return error; + } + + if (in_group_p(inode->i_gid)) + mode >>= 3; + } + + /* + * If the DACs are ok we don't need any capability check. + */ + if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) + return 0; + return -EACCES; +} + +/** + * generic_permission - check for access rights on a Posix-like filesystem + * @inode: inode to check access rights for + * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) + * + * Used to check for read/write/execute permissions on a file. + * We use "fsuid" for this, letting us set arbitrary permissions + * for filesystem access without changing the "normal" uids which + * are used for other things. + * + * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk + * request cannot be satisfied (eg. requires blocking or too much complexity). + * It would then be called again in ref-walk mode. + */ +int generic_permission(struct inode *inode, int mask) +{ + int ret; + + /* + * Do the basic permission checks. + */ + ret = acl_permission_check(inode, mask); + if (ret != -EACCES) + return ret; + + if (S_ISDIR(inode->i_mode)) { + /* DACs are overridable for directories */ + if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) + return 0; + if (!(mask & MAY_WRITE)) + if (capable_wrt_inode_uidgid(inode, + CAP_DAC_READ_SEARCH)) + return 0; + return -EACCES; + } + /* + * Read/write DACs are always overridable. + * Executable DACs are overridable when there is + * at least one exec bit set. + */ + if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) + if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) + return 0; + + /* + * Searching includes executable on directories, else just read. + */ + mask &= MAY_READ | MAY_WRITE | MAY_EXEC; + if (mask == MAY_READ) + if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) + return 0; + + return -EACCES; +} +EXPORT_SYMBOL(generic_permission); + +/* + * We _really_ want to just do "generic_permission()" without + * even looking at the inode->i_op values. So we keep a cache + * flag in inode->i_opflags, that says "this has not special + * permission function, use the fast case". + */ +static inline int do_inode_permission(struct inode *inode, int mask) +{ + if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { + if (likely(inode->i_op->permission)) + return inode->i_op->permission(inode, mask); + + /* This gets set once for the inode lifetime */ + spin_lock(&inode->i_lock); + inode->i_opflags |= IOP_FASTPERM; + spin_unlock(&inode->i_lock); + } + return generic_permission(inode, mask); +} + +/** + * __inode_permission - Check for access rights to a given inode + * @inode: Inode to check permission on + * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) + * + * Check for read/write/execute permissions on an inode. + * + * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. + * + * This does not check for a read-only file system. You probably want + * inode_permission(). + */ +int __inode_permission(struct inode *inode, int mask) +{ + int retval; + + if (unlikely(mask & MAY_WRITE)) { + /* + * Nobody gets write access to an immutable file. + */ + if (IS_IMMUTABLE(inode)) + return -EACCES; + } + + retval = do_inode_permission(inode, mask); + if (retval) + return retval; + + retval = devcgroup_inode_permission(inode, mask); + if (retval) + return retval; + + return security_inode_permission(inode, mask); +} +EXPORT_SYMBOL(__inode_permission); + +/** + * sb_permission - Check superblock-level permissions + * @sb: Superblock of inode to check permission on + * @inode: Inode to check permission on + * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) + * + * Separate out file-system wide checks from inode-specific permission checks. + */ +static int sb_permission(struct super_block *sb, struct inode *inode, int mask) +{ + if (unlikely(mask & MAY_WRITE)) { + umode_t mode = inode->i_mode; + + /* Nobody gets write access to a read-only fs. */ + if ((sb->s_flags & MS_RDONLY) && + (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) + return -EROFS; + } + return 0; +} + +/** + * inode_permission - Check for access rights to a given inode + * @inode: Inode to check permission on + * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) + * + * Check for read/write/execute permissions on an inode. We use fs[ug]id for + * this, letting us set arbitrary permissions for filesystem access without + * changing the "normal" UIDs which are used for other things. + * + * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. + */ +int inode_permission(struct inode *inode, int mask) +{ + int retval; + + retval = sb_permission(inode->i_sb, inode, mask); + if (retval) + return retval; + return __inode_permission(inode, mask); +} +EXPORT_SYMBOL(inode_permission); + +/** + * path_get - get a reference to a path + * @path: path to get the reference to + * + * Given a path increment the reference count to the dentry and the vfsmount. + */ +void path_get(const struct path *path) +{ + mntget(path->mnt); + dget(path->dentry); +} +EXPORT_SYMBOL(path_get); + +/** + * path_put - put a reference to a path + * @path: path to put the reference to + * + * Given a path decrement the reference count to the dentry and the vfsmount. + */ +void path_put(const struct path *path) +{ + dput(path->dentry); + mntput(path->mnt); +} +EXPORT_SYMBOL(path_put); + +struct nameidata { + struct path path; + struct qstr last; + struct path root; + struct inode *inode; /* path.dentry.d_inode */ + unsigned int flags; + unsigned seq, m_seq; + int last_type; + unsigned depth; + struct file *base; + char *saved_names[MAX_NESTED_LINKS + 1]; +}; + +/* + * Path walking has 2 modes, rcu-walk and ref-walk (see + * Documentation/filesystems/path-lookup.txt). In situations when we can't + * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab + * normal reference counts on dentries and vfsmounts to transition to rcu-walk + * mode. Refcounts are grabbed at the last known good point before rcu-walk + * got stuck, so ref-walk may continue from there. If this is not successful + * (eg. a seqcount has changed), then failure is returned and it's up to caller + * to restart the path walk from the beginning in ref-walk mode. + */ + +/** + * unlazy_walk - try to switch to ref-walk mode. + * @nd: nameidata pathwalk data + * @dentry: child of nd->path.dentry or NULL + * Returns: 0 on success, -ECHILD on failure + * + * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry + * for ref-walk mode. @dentry must be a path found by a do_lookup call on + * @nd or NULL. Must be called from rcu-walk context. + */ +static int unlazy_walk(struct nameidata *nd, struct dentry *dentry) +{ + struct fs_struct *fs = current->fs; + struct dentry *parent = nd->path.dentry; + + BUG_ON(!(nd->flags & LOOKUP_RCU)); + + /* + * After legitimizing the bastards, terminate_walk() + * will do the right thing for non-RCU mode, and all our + * subsequent exit cases should rcu_read_unlock() + * before returning. Do vfsmount first; if dentry + * can't be legitimized, just set nd->path.dentry to NULL + * and rely on dput(NULL) being a no-op. + */ + if (!legitimize_mnt(nd->path.mnt, nd->m_seq)) + return -ECHILD; + nd->flags &= ~LOOKUP_RCU; + + if (!lockref_get_not_dead(&parent->d_lockref)) { + nd->path.dentry = NULL; + goto out; + } + + /* + * For a negative lookup, the lookup sequence point is the parents + * sequence point, and it only needs to revalidate the parent dentry. + * + * For a positive lookup, we need to move both the parent and the + * dentry from the RCU domain to be properly refcounted. And the + * sequence number in the dentry validates *both* dentry counters, + * since we checked the sequence number of the parent after we got + * the child sequence number. So we know the parent must still + * be valid if the child sequence number is still valid. + */ + if (!dentry) { + if (read_seqcount_retry(&parent->d_seq, nd->seq)) + goto out; + BUG_ON(nd->inode != parent->d_inode); + } else { + if (!lockref_get_not_dead(&dentry->d_lockref)) + goto out; + if (read_seqcount_retry(&dentry->d_seq, nd->seq)) + goto drop_dentry; + } + + /* + * Sequence counts matched. Now make sure that the root is + * still valid and get it if required. + */ + if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { + spin_lock(&fs->lock); + if (nd->root.mnt != fs->root.mnt || nd->root.dentry != fs->root.dentry) + goto unlock_and_drop_dentry; + path_get(&nd->root); + spin_unlock(&fs->lock); + } + + rcu_read_unlock(); + return 0; + +unlock_and_drop_dentry: + spin_unlock(&fs->lock); +drop_dentry: + rcu_read_unlock(); + dput(dentry); + goto drop_root_mnt; +out: + rcu_read_unlock(); +drop_root_mnt: + if (!(nd->flags & LOOKUP_ROOT)) + nd->root.mnt = NULL; + return -ECHILD; +} + +static inline int d_revalidate(struct dentry *dentry, unsigned int flags) +{ + return dentry->d_op->d_revalidate(dentry, flags); +} + +/** + * complete_walk - successful completion of path walk + * @nd: pointer nameidata + * + * If we had been in RCU mode, drop out of it and legitimize nd->path. + * Revalidate the final result, unless we'd already done that during + * the path walk or the filesystem doesn't ask for it. Return 0 on + * success, -error on failure. In case of failure caller does not + * need to drop nd->path. + */ +static int complete_walk(struct nameidata *nd) +{ + struct dentry *dentry = nd->path.dentry; + int status; + + if (nd->flags & LOOKUP_RCU) { + nd->flags &= ~LOOKUP_RCU; + if (!(nd->flags & LOOKUP_ROOT)) + nd->root.mnt = NULL; + + if (!legitimize_mnt(nd->path.mnt, nd->m_seq)) { + rcu_read_unlock(); + return -ECHILD; + } + if (unlikely(!lockref_get_not_dead(&dentry->d_lockref))) { + rcu_read_unlock(); + mntput(nd->path.mnt); + return -ECHILD; + } + if (read_seqcount_retry(&dentry->d_seq, nd->seq)) { + rcu_read_unlock(); + dput(dentry); + mntput(nd->path.mnt); + return -ECHILD; + } + rcu_read_unlock(); + } + + if (likely(!(nd->flags & LOOKUP_JUMPED))) + return 0; + + if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) + return 0; + + status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); + if (status > 0) + return 0; + + if (!status) + status = -ESTALE; + + path_put(&nd->path); + return status; +} + +static __always_inline void set_root(struct nameidata *nd) +{ + get_fs_root(current->fs, &nd->root); +} + +static int link_path_walk(const char *, struct nameidata *); + +static __always_inline unsigned set_root_rcu(struct nameidata *nd) +{ + struct fs_struct *fs = current->fs; + unsigned seq, res; + + do { + seq = read_seqcount_begin(&fs->seq); + nd->root = fs->root; + res = __read_seqcount_begin(&nd->root.dentry->d_seq); + } while (read_seqcount_retry(&fs->seq, seq)); + return res; +} + +static void path_put_conditional(struct path *path, struct nameidata *nd) +{ + dput(path->dentry); + if (path->mnt != nd->path.mnt) + mntput(path->mnt); +} + +static inline void path_to_nameidata(const struct path *path, + struct nameidata *nd) +{ + if (!(nd->flags & LOOKUP_RCU)) { + dput(nd->path.dentry); + if (nd->path.mnt != path->mnt) + mntput(nd->path.mnt); + } + nd->path.mnt = path->mnt; + nd->path.dentry = path->dentry; +} + +/* + * Helper to directly jump to a known parsed path from ->follow_link, + * caller must have taken a reference to path beforehand. + */ +void nd_jump_link(struct nameidata *nd, struct path *path) +{ + path_put(&nd->path); + + nd->path = *path; + nd->inode = nd->path.dentry->d_inode; + nd->flags |= LOOKUP_JUMPED; +} + +void nd_set_link(struct nameidata *nd, char *path) +{ + nd->saved_names[nd->depth] = path; +} +EXPORT_SYMBOL(nd_set_link); + +char *nd_get_link(struct nameidata *nd) +{ + return nd->saved_names[nd->depth]; +} +EXPORT_SYMBOL(nd_get_link); + +static inline void put_link(struct nameidata *nd, struct path *link, void *cookie) +{ + struct inode *inode = link->dentry->d_inode; + if (inode->i_op->put_link) + inode->i_op->put_link(link->dentry, nd, cookie); + path_put(link); +} + +int sysctl_protected_symlinks __read_mostly = 0; +int sysctl_protected_hardlinks __read_mostly = 0; + +/** + * may_follow_link - Check symlink following for unsafe situations + * @link: The path of the symlink + * @nd: nameidata pathwalk data + * + * In the case of the sysctl_protected_symlinks sysctl being enabled, + * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is + * in a sticky world-writable directory. This is to protect privileged + * processes from failing races against path names that may change out + * from under them by way of other users creating malicious symlinks. + * It will permit symlinks to be followed only when outside a sticky + * world-writable directory, or when the uid of the symlink and follower + * match, or when the directory owner matches the symlink's owner. + * + * Returns 0 if following the symlink is allowed, -ve on error. + */ +static inline int may_follow_link(struct path *link, struct nameidata *nd) +{ + const struct inode *inode; + const struct inode *parent; + + if (!sysctl_protected_symlinks) + return 0; + + /* Allowed if owner and follower match. */ + inode = link->dentry->d_inode; + if (uid_eq(current_cred()->fsuid, inode->i_uid)) + return 0; + + /* Allowed if parent directory not sticky and world-writable. */ + parent = nd->path.dentry->d_inode; + if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) + return 0; + + /* Allowed if parent directory and link owner match. */ + if (uid_eq(parent->i_uid, inode->i_uid)) + return 0; + + audit_log_link_denied("follow_link", link); + path_put_conditional(link, nd); + path_put(&nd->path); + return -EACCES; +} + +/** + * safe_hardlink_source - Check for safe hardlink conditions + * @inode: the source inode to hardlink from + * + * Return false if at least one of the following conditions: + * - inode is not a regular file + * - inode is setuid + * - inode is setgid and group-exec + * - access failure for read and write + * + * Otherwise returns true. + */ +static bool safe_hardlink_source(struct inode *inode) +{ + umode_t mode = inode->i_mode; + + /* Special files should not get pinned to the filesystem. */ + if (!S_ISREG(mode)) + return false; + + /* Setuid files should not get pinned to the filesystem. */ + if (mode & S_ISUID) + return false; + + /* Executable setgid files should not get pinned to the filesystem. */ + if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) + return false; + + /* Hardlinking to unreadable or unwritable sources is dangerous. */ + if (inode_permission(inode, MAY_READ | MAY_WRITE)) + return false; + + return true; +} + +/** + * may_linkat - Check permissions for creating a hardlink + * @link: the source to hardlink from + * + * Block hardlink when all of: + * - sysctl_protected_hardlinks enabled + * - fsuid does not match inode + * - hardlink source is unsafe (see safe_hardlink_source() above) + * - not CAP_FOWNER + * + * Returns 0 if successful, -ve on error. + */ +static int may_linkat(struct path *link) +{ + const struct cred *cred; + struct inode *inode; + + if (!sysctl_protected_hardlinks) + return 0; + + cred = current_cred(); + inode = link->dentry->d_inode; + + /* Source inode owner (or CAP_FOWNER) can hardlink all they like, + * otherwise, it must be a safe source. + */ + if (uid_eq(cred->fsuid, inode->i_uid) || safe_hardlink_source(inode) || + capable(CAP_FOWNER)) + return 0; + + audit_log_link_denied("linkat", link); + return -EPERM; +} + +static __always_inline int +follow_link(struct path *link, struct nameidata *nd, void **p) +{ + struct dentry *dentry = link->dentry; + int error; + char *s; + + BUG_ON(nd->flags & LOOKUP_RCU); + + if (link->mnt == nd->path.mnt) + mntget(link->mnt); + + error = -ELOOP; + if (unlikely(current->total_link_count >= 40)) + goto out_put_nd_path; + + cond_resched(); + current->total_link_count++; + + touch_atime(link); + nd_set_link(nd, NULL); + + error = security_inode_follow_link(link->dentry, nd); + if (error) + goto out_put_nd_path; + + nd->last_type = LAST_BIND; + *p = dentry->d_inode->i_op->follow_link(dentry, nd); + error = PTR_ERR(*p); + if (IS_ERR(*p)) + goto out_put_nd_path; + + error = 0; + s = nd_get_link(nd); + if (s) { + if (unlikely(IS_ERR(s))) { + path_put(&nd->path); + put_link(nd, link, *p); + return PTR_ERR(s); + } + if (*s == '/') { + if (!nd->root.mnt) + set_root(nd); + path_put(&nd->path); + nd->path = nd->root; + path_get(&nd->root); + nd->flags |= LOOKUP_JUMPED; + } + nd->inode = nd->path.dentry->d_inode; + error = link_path_walk(s, nd); + if (unlikely(error)) + put_link(nd, link, *p); + } + + return error; + +out_put_nd_path: + *p = NULL; + path_put(&nd->path); + path_put(link); + return error; +} + +static int follow_up_rcu(struct path *path) +{ + struct mount *mnt = real_mount(path->mnt); + struct mount *parent; + struct dentry *mountpoint; + + parent = mnt->mnt_parent; + if (&parent->mnt == path->mnt) + return 0; + mountpoint = mnt->mnt_mountpoint; + path->dentry = mountpoint; + path->mnt = &parent->mnt; + return 1; +} + +/* + * follow_up - Find the mountpoint of path's vfsmount + * + * Given a path, find the mountpoint of its source file system. + * Replace @path with the path of the mountpoint in the parent mount. + * Up is towards /. + * + * Return 1 if we went up a level and 0 if we were already at the + * root. + */ +int follow_up(struct path *path) +{ + struct mount *mnt = real_mount(path->mnt); + struct mount *parent; + struct dentry *mountpoint; + + read_seqlock_excl(&mount_lock); + parent = mnt->mnt_parent; + if (parent == mnt) { + read_sequnlock_excl(&mount_lock); + return 0; + } + mntget(&parent->mnt); + mountpoint = dget(mnt->mnt_mountpoint); + read_sequnlock_excl(&mount_lock); + dput(path->dentry); + path->dentry = mountpoint; + mntput(path->mnt); + path->mnt = &parent->mnt; + return 1; +} +EXPORT_SYMBOL(follow_up); + +/* + * Perform an automount + * - return -EISDIR to tell follow_managed() to stop and return the path we + * were called with. + */ +static int follow_automount(struct path *path, unsigned flags, + bool *need_mntput) +{ + struct vfsmount *mnt; + int err; + + if (!path->dentry->d_op || !path->dentry->d_op->d_automount) + return -EREMOTE; + + /* We don't want to mount if someone's just doing a stat - + * unless they're stat'ing a directory and appended a '/' to + * the name. + * + * We do, however, want to mount if someone wants to open or + * create a file of any type under the mountpoint, wants to + * traverse through the mountpoint or wants to open the + * mounted directory. Also, autofs may mark negative dentries + * as being automount points. These will need the attentions + * of the daemon to instantiate them before they can be used. + */ + if (!(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | + LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && + path->dentry->d_inode) + return -EISDIR; + + current->total_link_count++; + if (current->total_link_count >= 40) + return -ELOOP; + + mnt = path->dentry->d_op->d_automount(path); + if (IS_ERR(mnt)) { + /* + * The filesystem is allowed to return -EISDIR here to indicate + * it doesn't want to automount. For instance, autofs would do + * this so that its userspace daemon can mount on this dentry. + * + * However, we can only permit this if it's a terminal point in + * the path being looked up; if it wasn't then the remainder of + * the path is inaccessible and we should say so. + */ + if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_PARENT)) + return -EREMOTE; + return PTR_ERR(mnt); + } + + if (!mnt) /* mount collision */ + return 0; + + if (!*need_mntput) { + /* lock_mount() may release path->mnt on error */ + mntget(path->mnt); + *need_mntput = true; + } + err = finish_automount(mnt, path); + + switch (err) { + case -EBUSY: + /* Someone else made a mount here whilst we were busy */ + return 0; + case 0: + path_put(path); + path->mnt = mnt; + path->dentry = dget(mnt->mnt_root); + return 0; + default: + return err; + } + +} + +/* + * Handle a dentry that is managed in some way. + * - Flagged for transit management (autofs) + * - Flagged as mountpoint + * - Flagged as automount point + * + * This may only be called in refwalk mode. + * + * Serialization is taken care of in namespace.c + */ +static int follow_managed(struct path *path, unsigned flags) +{ + struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ + unsigned managed; + bool need_mntput = false; + int ret = 0; + + /* Given that we're not holding a lock here, we retain the value in a + * local variable for each dentry as we look at it so that we don't see + * the components of that value change under us */ + while (managed = ACCESS_ONCE(path->dentry->d_flags), + managed &= DCACHE_MANAGED_DENTRY, + unlikely(managed != 0)) { + /* Allow the filesystem to manage the transit without i_mutex + * being held. */ + if (managed & DCACHE_MANAGE_TRANSIT) { + BUG_ON(!path->dentry->d_op); + BUG_ON(!path->dentry->d_op->d_manage); + ret = path->dentry->d_op->d_manage(path->dentry, false); + if (ret < 0) + break; + } + + /* Transit to a mounted filesystem. */ + if (managed & DCACHE_MOUNTED) { + struct vfsmount *mounted = lookup_mnt(path); + if (mounted) { + dput(path->dentry); + if (need_mntput) + mntput(path->mnt); + path->mnt = mounted; + path->dentry = dget(mounted->mnt_root); + need_mntput = true; + continue; + } + + /* Something is mounted on this dentry in another + * namespace and/or whatever was mounted there in this + * namespace got unmounted before lookup_mnt() could + * get it */ + } + + /* Handle an automount point */ + if (managed & DCACHE_NEED_AUTOMOUNT) { + ret = follow_automount(path, flags, &need_mntput); + if (ret < 0) + break; + continue; + } + + /* We didn't change the current path point */ + break; + } + + if (need_mntput && path->mnt == mnt) + mntput(path->mnt); + if (ret == -EISDIR) + ret = 0; + return ret < 0 ? ret : need_mntput; +} + +int follow_down_one(struct path *path) +{ + struct vfsmount *mounted; + + mounted = lookup_mnt(path); + if (mounted) { + dput(path->dentry); + mntput(path->mnt); + path->mnt = mounted; + path->dentry = dget(mounted->mnt_root); + return 1; + } + return 0; +} +EXPORT_SYMBOL(follow_down_one); + +static inline int managed_dentry_rcu(struct dentry *dentry) +{ + return (dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? + dentry->d_op->d_manage(dentry, true) : 0; +} + +/* + * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if + * we meet a managed dentry that would need blocking. + */ +static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, + struct inode **inode) +{ + for (;;) { + struct mount *mounted; + /* + * Don't forget we might have a non-mountpoint managed dentry + * that wants to block transit. + */ + switch (managed_dentry_rcu(path->dentry)) { + case -ECHILD: + default: + return false; + case -EISDIR: + return true; + case 0: + break; + } + + if (!d_mountpoint(path->dentry)) + return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); + + mounted = __lookup_mnt(path->mnt, path->dentry); + if (!mounted) + break; + path->mnt = &mounted->mnt; + path->dentry = mounted->mnt.mnt_root; + nd->flags |= LOOKUP_JUMPED; + nd->seq = read_seqcount_begin(&path->dentry->d_seq); + /* + * Update the inode too. We don't need to re-check the + * dentry sequence number here after this d_inode read, + * because a mount-point is always pinned. + */ + *inode = path->dentry->d_inode; + } + return !read_seqretry(&mount_lock, nd->m_seq) && + !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); +} + +static int follow_dotdot_rcu(struct nameidata *nd) +{ + struct inode *inode = nd->inode; + if (!nd->root.mnt) + set_root_rcu(nd); + + while (1) { + if (nd->path.dentry == nd->root.dentry && + nd->path.mnt == nd->root.mnt) { + break; + } + if (nd->path.dentry != nd->path.mnt->mnt_root) { + struct dentry *old = nd->path.dentry; + struct dentry *parent = old->d_parent; + unsigned seq; + + inode = parent->d_inode; + seq = read_seqcount_begin(&parent->d_seq); + if (read_seqcount_retry(&old->d_seq, nd->seq)) + goto failed; + nd->path.dentry = parent; + nd->seq = seq; + break; + } + if (!follow_up_rcu(&nd->path)) + break; + inode = nd->path.dentry->d_inode; + nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); + } + while (d_mountpoint(nd->path.dentry)) { + struct mount *mounted; + mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); + if (!mounted) + break; + nd->path.mnt = &mounted->mnt; + nd->path.dentry = mounted->mnt.mnt_root; + inode = nd->path.dentry->d_inode; + nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); + if (read_seqretry(&mount_lock, nd->m_seq)) + goto failed; + } + nd->inode = inode; + return 0; + +failed: + nd->flags &= ~LOOKUP_RCU; + if (!(nd->flags & LOOKUP_ROOT)) + nd->root.mnt = NULL; + rcu_read_unlock(); + return -ECHILD; +} + +/* + * Follow down to the covering mount currently visible to userspace. At each + * point, the filesystem owning that dentry may be queried as to whether the + * caller is permitted to proceed or not. + */ +int follow_down(struct path *path) +{ + unsigned managed; + int ret; + + while (managed = ACCESS_ONCE(path->dentry->d_flags), + unlikely(managed & DCACHE_MANAGED_DENTRY)) { + /* Allow the filesystem to manage the transit without i_mutex + * being held. + * + * We indicate to the filesystem if someone is trying to mount + * something here. This gives autofs the chance to deny anyone + * other than its daemon the right to mount on its + * superstructure. + * + * The filesystem may sleep at this point. + */ + if (managed & DCACHE_MANAGE_TRANSIT) { + BUG_ON(!path->dentry->d_op); + BUG_ON(!path->dentry->d_op->d_manage); + ret = path->dentry->d_op->d_manage( + path->dentry, false); + if (ret < 0) + return ret == -EISDIR ? 0 : ret; + } + + /* Transit to a mounted filesystem. */ + if (managed & DCACHE_MOUNTED) { + struct vfsmount *mounted = lookup_mnt(path); + if (!mounted) + break; + dput(path->dentry); + mntput(path->mnt); + path->mnt = mounted; + path->dentry = dget(mounted->mnt_root); + continue; + } + + /* Don't handle automount points here */ + break; + } + return 0; +} +EXPORT_SYMBOL(follow_down); + +/* + * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() + */ +static void follow_mount(struct path *path) +{ + while (d_mountpoint(path->dentry)) { + struct vfsmount *mounted = lookup_mnt(path); + if (!mounted) + break; + dput(path->dentry); + mntput(path->mnt); + path->mnt = mounted; + path->dentry = dget(mounted->mnt_root); + } +} + +static void follow_dotdot(struct nameidata *nd) +{ + if (!nd->root.mnt) + set_root(nd); + + while(1) { + struct dentry *old = nd->path.dentry; + + if (nd->path.dentry == nd->root.dentry && + nd->path.mnt == nd->root.mnt) { + break; + } + if (nd->path.dentry != nd->path.mnt->mnt_root) { + /* rare case of legitimate dget_parent()... */ + nd->path.dentry = dget_parent(nd->path.dentry); + dput(old); + break; + } + if (!follow_up(&nd->path)) + break; + } + follow_mount(&nd->path); + nd->inode = nd->path.dentry->d_inode; +} + +/* + * This looks up the name in dcache, possibly revalidates the old dentry and + * allocates a new one if not found or not valid. In the need_lookup argument + * returns whether i_op->lookup is necessary. + * + * dir->d_inode->i_mutex must be held + */ +static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, + unsigned int flags, bool *need_lookup) +{ + struct dentry *dentry; + int error; + + *need_lookup = false; + dentry = d_lookup(dir, name); + if (dentry) { + if (dentry->d_flags & DCACHE_OP_REVALIDATE) { + error = d_revalidate(dentry, flags); + if (unlikely(error <= 0)) { + if (error < 0) { + dput(dentry); + return ERR_PTR(error); + } else { + d_invalidate(dentry); + dput(dentry); + dentry = NULL; + } + } + } + } + + if (!dentry) { + dentry = d_alloc(dir, name); + if (unlikely(!dentry)) + return ERR_PTR(-ENOMEM); + + *need_lookup = true; + } + return dentry; +} + +/* + * Call i_op->lookup on the dentry. The dentry must be negative and + * unhashed. + * + * dir->d_inode->i_mutex must be held + */ +static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, + unsigned int flags) +{ + struct dentry *old; + + /* Don't create child dentry for a dead directory. */ + if (unlikely(IS_DEADDIR(dir))) { + dput(dentry); + return ERR_PTR(-ENOENT); + } + + old = dir->i_op->lookup(dir, dentry, flags); + if (unlikely(old)) { + dput(dentry); + dentry = old; + } + return dentry; +} + +static struct dentry *__lookup_hash(struct qstr *name, + struct dentry *base, unsigned int flags) +{ + bool need_lookup; + struct dentry *dentry; + + dentry = lookup_dcache(name, base, flags, &need_lookup); + if (!need_lookup) + return dentry; + + return lookup_real(base->d_inode, dentry, flags); +} + +/* + * It's more convoluted than I'd like it to be, but... it's still fairly + * small and for now I'd prefer to have fast path as straight as possible. + * It _is_ time-critical. + */ +static int lookup_fast(struct nameidata *nd, + struct path *path, struct inode **inode) +{ + struct vfsmount *mnt = nd->path.mnt; + struct dentry *dentry, *parent = nd->path.dentry; + int need_reval = 1; + int status = 1; + int err; + + /* + * Rename seqlock is not required here because in the off chance + * of a false negative due to a concurrent rename, we're going to + * do the non-racy lookup, below. + */ + if (nd->flags & LOOKUP_RCU) { + unsigned seq; + bool negative; + dentry = __d_lookup_rcu(parent, &nd->last, &seq); + if (!dentry) + goto unlazy; + + /* + * This sequence count validates that the inode matches + * the dentry name information from lookup. + */ + *inode = dentry->d_inode; + negative = d_is_negative(dentry); + if (read_seqcount_retry(&dentry->d_seq, seq)) + return -ECHILD; + if (negative) + return -ENOENT; + + /* + * This sequence count validates that the parent had no + * changes while we did the lookup of the dentry above. + * + * The memory barrier in read_seqcount_begin of child is + * enough, we can use __read_seqcount_retry here. + */ + if (__read_seqcount_retry(&parent->d_seq, nd->seq)) + return -ECHILD; + nd->seq = seq; + + if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { + status = d_revalidate(dentry, nd->flags); + if (unlikely(status <= 0)) { + if (status != -ECHILD) + need_reval = 0; + goto unlazy; + } + } + path->mnt = mnt; + path->dentry = dentry; + if (likely(__follow_mount_rcu(nd, path, inode))) + return 0; +unlazy: + if (unlazy_walk(nd, dentry)) + return -ECHILD; + } else { + dentry = __d_lookup(parent, &nd->last); + } + + if (unlikely(!dentry)) + goto need_lookup; + + if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) + status = d_revalidate(dentry, nd->flags); + if (unlikely(status <= 0)) { + if (status < 0) { + dput(dentry); + return status; + } + d_invalidate(dentry); + dput(dentry); + goto need_lookup; + } + + if (unlikely(d_is_negative(dentry))) { + dput(dentry); + return -ENOENT; + } + path->mnt = mnt; + path->dentry = dentry; + err = follow_managed(path, nd->flags); + if (unlikely(err < 0)) { + path_put_conditional(path, nd); + return err; + } + if (err) + nd->flags |= LOOKUP_JUMPED; + *inode = path->dentry->d_inode; + return 0; + +need_lookup: + return 1; +} + +/* Fast lookup failed, do it the slow way */ +static int lookup_slow(struct nameidata *nd, struct path *path) +{ + struct dentry *dentry, *parent; + int err; + + parent = nd->path.dentry; + BUG_ON(nd->inode != parent->d_inode); + + mutex_lock(&parent->d_inode->i_mutex); + dentry = __lookup_hash(&nd->last, parent, nd->flags); + mutex_unlock(&parent->d_inode->i_mutex); + if (IS_ERR(dentry)) + return PTR_ERR(dentry); + path->mnt = nd->path.mnt; + path->dentry = dentry; + err = follow_managed(path, nd->flags); + if (unlikely(err < 0)) { + path_put_conditional(path, nd); + return err; + } + if (err) + nd->flags |= LOOKUP_JUMPED; + return 0; +} + +static inline int may_lookup(struct nameidata *nd) +{ + if (nd->flags & LOOKUP_RCU) { + int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); + if (err != -ECHILD) + return err; + if (unlazy_walk(nd, NULL)) + return -ECHILD; + } + return inode_permission(nd->inode, MAY_EXEC); +} + +static inline int handle_dots(struct nameidata *nd, int type) +{ + if (type == LAST_DOTDOT) { + if (nd->flags & LOOKUP_RCU) { + if (follow_dotdot_rcu(nd)) + return -ECHILD; + } else + follow_dotdot(nd); + } + return 0; +} + +static void terminate_walk(struct nameidata *nd) +{ + if (!(nd->flags & LOOKUP_RCU)) { + path_put(&nd->path); + } else { + nd->flags &= ~LOOKUP_RCU; + if (!(nd->flags & LOOKUP_ROOT)) + nd->root.mnt = NULL; + rcu_read_unlock(); + } +} + +/* + * Do we need to follow links? We _really_ want to be able + * to do this check without having to look at inode->i_op, + * so we keep a cache of "no, this doesn't need follow_link" + * for the common case. + */ +static inline int should_follow_link(struct dentry *dentry, int follow) +{ + return unlikely(d_is_symlink(dentry)) ? follow : 0; +} + +static inline int walk_component(struct nameidata *nd, struct path *path, + int follow) +{ + struct inode *inode; + int err; + /* + * "." and ".." are special - ".." especially so because it has + * to be able to know about the current root directory and + * parent relationships. + */ + if (unlikely(nd->last_type != LAST_NORM)) + return handle_dots(nd, nd->last_type); + err = lookup_fast(nd, path, &inode); + if (unlikely(err)) { + if (err < 0) + goto out_err; + + err = lookup_slow(nd, path); + if (err < 0) + goto out_err; + + inode = path->dentry->d_inode; + err = -ENOENT; + if (d_is_negative(path->dentry)) + goto out_path_put; + } + + if (should_follow_link(path->dentry, follow)) { + if (nd->flags & LOOKUP_RCU) { + if (unlikely(nd->path.mnt != path->mnt || + unlazy_walk(nd, path->dentry))) { + err = -ECHILD; + goto out_err; + } + } + BUG_ON(inode != path->dentry->d_inode); + return 1; + } + path_to_nameidata(path, nd); + nd->inode = inode; + return 0; + +out_path_put: + path_to_nameidata(path, nd); +out_err: + terminate_walk(nd); + return err; +} + +/* + * This limits recursive symlink follows to 8, while + * limiting consecutive symlinks to 40. + * + * Without that kind of total limit, nasty chains of consecutive + * symlinks can cause almost arbitrarily long lookups. + */ +static inline int nested_symlink(struct path *path, struct nameidata *nd) +{ + int res; + + if (unlikely(current->link_count >= MAX_NESTED_LINKS)) { + path_put_conditional(path, nd); + path_put(&nd->path); + return -ELOOP; + } + BUG_ON(nd->depth >= MAX_NESTED_LINKS); + + nd->depth++; + current->link_count++; + + do { + struct path link = *path; + void *cookie; + + res = follow_link(&link, nd, &cookie); + if (res) + break; + res = walk_component(nd, path, LOOKUP_FOLLOW); + put_link(nd, &link, cookie); + } while (res > 0); + + current->link_count--; + nd->depth--; + return res; +} + +/* + * We can do the critical dentry name comparison and hashing + * operations one word at a time, but we are limited to: + * + * - Architectures with fast unaligned word accesses. We could + * do a "get_unaligned()" if this helps and is sufficiently + * fast. + * + * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we + * do not trap on the (extremely unlikely) case of a page + * crossing operation. + * + * - Furthermore, we need an efficient 64-bit compile for the + * 64-bit case in order to generate the "number of bytes in + * the final mask". Again, that could be replaced with a + * efficient population count instruction or similar. + */ +#ifdef CONFIG_DCACHE_WORD_ACCESS + +#include <asm/word-at-a-time.h> + +#ifdef CONFIG_64BIT + +static inline unsigned int fold_hash(unsigned long hash) +{ + return hash_64(hash, 32); +} + +#else /* 32-bit case */ + +#define fold_hash(x) (x) + +#endif + +unsigned int full_name_hash(const unsigned char *name, unsigned int len) +{ + unsigned long a, mask; + unsigned long hash = 0; + + for (;;) { + a = load_unaligned_zeropad(name); + if (len < sizeof(unsigned long)) + break; + hash += a; + hash *= 9; + name += sizeof(unsigned long); + len -= sizeof(unsigned long); + if (!len) + goto done; + } + mask = bytemask_from_count(len); + hash += mask & a; +done: + return fold_hash(hash); +} +EXPORT_SYMBOL(full_name_hash); + +/* + * Calculate the length and hash of the path component, and + * return the "hash_len" as the result. + */ +static inline u64 hash_name(const char *name) +{ + unsigned long a, b, adata, bdata, mask, hash, len; + const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; + + hash = a = 0; + len = -sizeof(unsigned long); + do { + hash = (hash + a) * 9; + len += sizeof(unsigned long); + a = load_unaligned_zeropad(name+len); + b = a ^ REPEAT_BYTE('/'); + } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); + + adata = prep_zero_mask(a, adata, &constants); + bdata = prep_zero_mask(b, bdata, &constants); + + mask = create_zero_mask(adata | bdata); + + hash += a & zero_bytemask(mask); + len += find_zero(mask); + return hashlen_create(fold_hash(hash), len); +} + +#else + +unsigned int full_name_hash(const unsigned char *name, unsigned int len) +{ + unsigned long hash = init_name_hash(); + while (len--) + hash = partial_name_hash(*name++, hash); + return end_name_hash(hash); +} +EXPORT_SYMBOL(full_name_hash); + +/* + * We know there's a real path component here of at least + * one character. + */ +static inline u64 hash_name(const char *name) +{ + unsigned long hash = init_name_hash(); + unsigned long len = 0, c; + + c = (unsigned char)*name; + do { + len++; + hash = partial_name_hash(c, hash); + c = (unsigned char)name[len]; + } while (c && c != '/'); + return hashlen_create(end_name_hash(hash), len); +} + +#endif + +/* + * Name resolution. + * This is the basic name resolution function, turning a pathname into + * the final dentry. We expect 'base' to be positive and a directory. + * + * Returns 0 and nd will have valid dentry and mnt on success. + * Returns error and drops reference to input namei data on failure. + */ +static int link_path_walk(const char *name, struct nameidata *nd) +{ + struct path next; + int err; + + while (*name=='/') + name++; + if (!*name) + return 0; + + /* At this point we know we have a real path component. */ + for(;;) { + u64 hash_len; + int type; + + err = may_lookup(nd); + if (err) + break; + + hash_len = hash_name(name); + + type = LAST_NORM; + if (name[0] == '.') switch (hashlen_len(hash_len)) { + case 2: + if (name[1] == '.') { + type = LAST_DOTDOT; + nd->flags |= LOOKUP_JUMPED; + } + break; + case 1: + type = LAST_DOT; + } + if (likely(type == LAST_NORM)) { + struct dentry *parent = nd->path.dentry; + nd->flags &= ~LOOKUP_JUMPED; + if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { + struct qstr this = { { .hash_len = hash_len }, .name = name }; + err = parent->d_op->d_hash(parent, &this); + if (err < 0) + break; + hash_len = this.hash_len; + name = this.name; + } + } + + nd->last.hash_len = hash_len; + nd->last.name = name; + nd->last_type = type; + + name += hashlen_len(hash_len); + if (!*name) + return 0; + /* + * If it wasn't NUL, we know it was '/'. Skip that + * slash, and continue until no more slashes. + */ + do { + name++; + } while (unlikely(*name == '/')); + if (!*name) + return 0; + + err = walk_component(nd, &next, LOOKUP_FOLLOW); + if (err < 0) + return err; + + if (err) { + err = nested_symlink(&next, nd); + if (err) + return err; + } + if (!d_can_lookup(nd->path.dentry)) { + err = -ENOTDIR; + break; + } + } + terminate_walk(nd); + return err; +} + +static int path_init(int dfd, const struct filename *name, unsigned int flags, + struct nameidata *nd) +{ + int retval = 0; + const char *s = name->name; + + nd->last_type = LAST_ROOT; /* if there are only slashes... */ + nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; + nd->depth = 0; + nd->base = NULL; + if (flags & LOOKUP_ROOT) { + struct dentry *root = nd->root.dentry; + struct inode *inode = root->d_inode; + if (*s) { + if (!d_can_lookup(root)) + return -ENOTDIR; + retval = inode_permission(inode, MAY_EXEC); + if (retval) + return retval; + } + nd->path = nd->root; + nd->inode = inode; + if (flags & LOOKUP_RCU) { + rcu_read_lock(); + nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); + nd->m_seq = read_seqbegin(&mount_lock); + } else { + path_get(&nd->path); + } + goto done; + } + + nd->root.mnt = NULL; + + nd->m_seq = read_seqbegin(&mount_lock); + if (*s == '/') { + if (flags & LOOKUP_RCU) { + rcu_read_lock(); + nd->seq = set_root_rcu(nd); + } else { + set_root(nd); + path_get(&nd->root); + } + nd->path = nd->root; + } else if (dfd == AT_FDCWD) { + if (flags & LOOKUP_RCU) { + struct fs_struct *fs = current->fs; + unsigned seq; + + rcu_read_lock(); + + do { + seq = read_seqcount_begin(&fs->seq); + nd->path = fs->pwd; + nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); + } while (read_seqcount_retry(&fs->seq, seq)); + } else { + get_fs_pwd(current->fs, &nd->path); + } + } else { + /* Caller must check execute permissions on the starting path component */ + struct fd f = fdget_raw(dfd); + struct dentry *dentry; + + if (!f.file) + return -EBADF; + + dentry = f.file->f_path.dentry; + + if (*s) { + if (!d_can_lookup(dentry)) { + fdput(f); + return -ENOTDIR; + } + } + + nd->path = f.file->f_path; + if (flags & LOOKUP_RCU) { + if (f.flags & FDPUT_FPUT) + nd->base = f.file; + nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); + rcu_read_lock(); + } else { + path_get(&nd->path); + fdput(f); + } + } + + nd->inode = nd->path.dentry->d_inode; + if (!(flags & LOOKUP_RCU)) + goto done; + if (likely(!read_seqcount_retry(&nd->path.dentry->d_seq, nd->seq))) + goto done; + if (!(nd->flags & LOOKUP_ROOT)) + nd->root.mnt = NULL; + rcu_read_unlock(); + return -ECHILD; +done: + current->total_link_count = 0; + return link_path_walk(s, nd); +} + +static void path_cleanup(struct nameidata *nd) +{ + if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { + path_put(&nd->root); + nd->root.mnt = NULL; + } + if (unlikely(nd->base)) + fput(nd->base); +} + +static inline int lookup_last(struct nameidata *nd, struct path *path) +{ + if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) + nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; + + nd->flags &= ~LOOKUP_PARENT; + return walk_component(nd, path, nd->flags & LOOKUP_FOLLOW); +} + +/* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ +static int path_lookupat(int dfd, const struct filename *name, + unsigned int flags, struct nameidata *nd) +{ + struct path path; + int err; + + /* + * Path walking is largely split up into 2 different synchronisation + * schemes, rcu-walk and ref-walk (explained in + * Documentation/filesystems/path-lookup.txt). These share much of the + * path walk code, but some things particularly setup, cleanup, and + * following mounts are sufficiently divergent that functions are + * duplicated. Typically there is a function foo(), and its RCU + * analogue, foo_rcu(). + * + * -ECHILD is the error number of choice (just to avoid clashes) that + * is returned if some aspect of an rcu-walk fails. Such an error must + * be handled by restarting a traditional ref-walk (which will always + * be able to complete). + */ + err = path_init(dfd, name, flags, nd); + if (!err && !(flags & LOOKUP_PARENT)) { + err = lookup_last(nd, &path); + while (err > 0) { + void *cookie; + struct path link = path; + err = may_follow_link(&link, nd); + if (unlikely(err)) + break; + nd->flags |= LOOKUP_PARENT; + err = follow_link(&link, nd, &cookie); + if (err) + break; + err = lookup_last(nd, &path); + put_link(nd, &link, cookie); + } + } + + if (!err) + err = complete_walk(nd); + + if (!err && nd->flags & LOOKUP_DIRECTORY) { + if (!d_can_lookup(nd->path.dentry)) { + path_put(&nd->path); + err = -ENOTDIR; + } + } + + path_cleanup(nd); + return err; +} + +static int filename_lookup(int dfd, struct filename *name, + unsigned int flags, struct nameidata *nd) +{ + int retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); + if (unlikely(retval == -ECHILD)) + retval = path_lookupat(dfd, name, flags, nd); + if (unlikely(retval == -ESTALE)) + retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); + + if (likely(!retval)) + audit_inode(name, nd->path.dentry, flags & LOOKUP_PARENT); + return retval; +} + +/* does lookup, returns the object with parent locked */ +struct dentry *kern_path_locked(const char *name, struct path *path) +{ + struct filename *filename = getname_kernel(name); + struct nameidata nd; + struct dentry *d; + int err; + + if (IS_ERR(filename)) + return ERR_CAST(filename); + + err = filename_lookup(AT_FDCWD, filename, LOOKUP_PARENT, &nd); + if (err) { + d = ERR_PTR(err); + goto out; + } + if (nd.last_type != LAST_NORM) { + path_put(&nd.path); + d = ERR_PTR(-EINVAL); + goto out; + } + mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); + d = __lookup_hash(&nd.last, nd.path.dentry, 0); + if (IS_ERR(d)) { + mutex_unlock(&nd.path.dentry->d_inode->i_mutex); + path_put(&nd.path); + goto out; + } + *path = nd.path; +out: + putname(filename); + return d; +} + +int kern_path(const char *name, unsigned int flags, struct path *path) +{ + struct nameidata nd; + struct filename *filename = getname_kernel(name); + int res = PTR_ERR(filename); + + if (!IS_ERR(filename)) { + res = filename_lookup(AT_FDCWD, filename, flags, &nd); + putname(filename); + if (!res) + *path = nd.path; + } + return res; +} +EXPORT_SYMBOL(kern_path); + +/** + * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair + * @dentry: pointer to dentry of the base directory + * @mnt: pointer to vfs mount of the base directory + * @name: pointer to file name + * @flags: lookup flags + * @path: pointer to struct path to fill + */ +int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, + const char *name, unsigned int flags, + struct path *path) +{ + struct filename *filename = getname_kernel(name); + int err = PTR_ERR(filename); + + BUG_ON(flags & LOOKUP_PARENT); + + /* the first argument of filename_lookup() is ignored with LOOKUP_ROOT */ + if (!IS_ERR(filename)) { + struct nameidata nd; + nd.root.dentry = dentry; + nd.root.mnt = mnt; + err = filename_lookup(AT_FDCWD, filename, + flags | LOOKUP_ROOT, &nd); + if (!err) + *path = nd.path; + putname(filename); + } + return err; +} +EXPORT_SYMBOL(vfs_path_lookup); + +/* + * Restricted form of lookup. Doesn't follow links, single-component only, + * needs parent already locked. Doesn't follow mounts. + * SMP-safe. + */ +static struct dentry *lookup_hash(struct nameidata *nd) +{ + return __lookup_hash(&nd->last, nd->path.dentry, nd->flags); +} + +/** + * lookup_one_len - filesystem helper to lookup single pathname component + * @name: pathname component to lookup + * @base: base directory to lookup from + * @len: maximum length @len should be interpreted to + * + * Note that this routine is purely a helper for filesystem usage and should + * not be called by generic code. + */ +struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) +{ + struct qstr this; + unsigned int c; + int err; + + WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); + + this.name = name; + this.len = len; + this.hash = full_name_hash(name, len); + if (!len) + return ERR_PTR(-EACCES); + + if (unlikely(name[0] == '.')) { + if (len < 2 || (len == 2 && name[1] == '.')) + return ERR_PTR(-EACCES); + } + + while (len--) { + c = *(const unsigned char *)name++; + if (c == '/' || c == '\0') + return ERR_PTR(-EACCES); + } + /* + * See if the low-level filesystem might want + * to use its own hash.. + */ + if (base->d_flags & DCACHE_OP_HASH) { + int err = base->d_op->d_hash(base, &this); + if (err < 0) + return ERR_PTR(err); + } + + err = inode_permission(base->d_inode, MAY_EXEC); + if (err) + return ERR_PTR(err); + + return __lookup_hash(&this, base, 0); +} +EXPORT_SYMBOL(lookup_one_len); + +int user_path_at_empty(int dfd, const char __user *name, unsigned flags, + struct path *path, int *empty) +{ + struct nameidata nd; + struct filename *tmp = getname_flags(name, flags, empty); + int err = PTR_ERR(tmp); + if (!IS_ERR(tmp)) { + + BUG_ON(flags & LOOKUP_PARENT); + + err = filename_lookup(dfd, tmp, flags, &nd); + putname(tmp); + if (!err) + *path = nd.path; + } + return err; +} + +int user_path_at(int dfd, const char __user *name, unsigned flags, + struct path *path) +{ + return user_path_at_empty(dfd, name, flags, path, NULL); +} +EXPORT_SYMBOL(user_path_at); + +/* + * NB: most callers don't do anything directly with the reference to the + * to struct filename, but the nd->last pointer points into the name string + * allocated by getname. So we must hold the reference to it until all + * path-walking is complete. + */ +static struct filename * +user_path_parent(int dfd, const char __user *path, struct nameidata *nd, + unsigned int flags) +{ + struct filename *s = getname(path); + int error; + + /* only LOOKUP_REVAL is allowed in extra flags */ + flags &= LOOKUP_REVAL; + + if (IS_ERR(s)) + return s; + + error = filename_lookup(dfd, s, flags | LOOKUP_PARENT, nd); + if (error) { + putname(s); + return ERR_PTR(error); + } + + return s; +} + +/** + * mountpoint_last - look up last component for umount + * @nd: pathwalk nameidata - currently pointing at parent directory of "last" + * @path: pointer to container for result + * + * This is a special lookup_last function just for umount. In this case, we + * need to resolve the path without doing any revalidation. + * + * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since + * mountpoints are always pinned in the dcache, their ancestors are too. Thus, + * in almost all cases, this lookup will be served out of the dcache. The only + * cases where it won't are if nd->last refers to a symlink or the path is + * bogus and it doesn't exist. + * + * Returns: + * -error: if there was an error during lookup. This includes -ENOENT if the + * lookup found a negative dentry. The nd->path reference will also be + * put in this case. + * + * 0: if we successfully resolved nd->path and found it to not to be a + * symlink that needs to be followed. "path" will also be populated. + * The nd->path reference will also be put. + * + * 1: if we successfully resolved nd->last and found it to be a symlink + * that needs to be followed. "path" will be populated with the path + * to the link, and nd->path will *not* be put. + */ +static int +mountpoint_last(struct nameidata *nd, struct path *path) +{ + int error = 0; + struct dentry *dentry; + struct dentry *dir = nd->path.dentry; + + /* If we're in rcuwalk, drop out of it to handle last component */ + if (nd->flags & LOOKUP_RCU) { + if (unlazy_walk(nd, NULL)) { + error = -ECHILD; + goto out; + } + } + + nd->flags &= ~LOOKUP_PARENT; + + if (unlikely(nd->last_type != LAST_NORM)) { + error = handle_dots(nd, nd->last_type); + if (error) + goto out; + dentry = dget(nd->path.dentry); + goto done; + } + + mutex_lock(&dir->d_inode->i_mutex); + dentry = d_lookup(dir, &nd->last); + if (!dentry) { + /* + * No cached dentry. Mounted dentries are pinned in the cache, + * so that means that this dentry is probably a symlink or the + * path doesn't actually point to a mounted dentry. + */ + dentry = d_alloc(dir, &nd->last); + if (!dentry) { + error = -ENOMEM; + mutex_unlock(&dir->d_inode->i_mutex); + goto out; + } + dentry = lookup_real(dir->d_inode, dentry, nd->flags); + error = PTR_ERR(dentry); + if (IS_ERR(dentry)) { + mutex_unlock(&dir->d_inode->i_mutex); + goto out; + } + } + mutex_unlock(&dir->d_inode->i_mutex); + +done: + if (d_is_negative(dentry)) { + error = -ENOENT; + dput(dentry); + goto out; + } + path->dentry = dentry; + path->mnt = nd->path.mnt; + if (should_follow_link(dentry, nd->flags & LOOKUP_FOLLOW)) + return 1; + mntget(path->mnt); + follow_mount(path); + error = 0; +out: + terminate_walk(nd); + return error; +} + +/** + * path_mountpoint - look up a path to be umounted + * @dfd: directory file descriptor to start walk from + * @name: full pathname to walk + * @path: pointer to container for result + * @flags: lookup flags + * + * Look up the given name, but don't attempt to revalidate the last component. + * Returns 0 and "path" will be valid on success; Returns error otherwise. + */ +static int +path_mountpoint(int dfd, const struct filename *name, struct path *path, + unsigned int flags) +{ + struct nameidata nd; + int err; + + err = path_init(dfd, name, flags, &nd); + if (unlikely(err)) + goto out; + + err = mountpoint_last(&nd, path); + while (err > 0) { + void *cookie; + struct path link = *path; + err = may_follow_link(&link, &nd); + if (unlikely(err)) + break; + nd.flags |= LOOKUP_PARENT; + err = follow_link(&link, &nd, &cookie); + if (err) + break; + err = mountpoint_last(&nd, path); + put_link(&nd, &link, cookie); + } +out: + path_cleanup(&nd); + return err; +} + +static int +filename_mountpoint(int dfd, struct filename *name, struct path *path, + unsigned int flags) +{ + int error; + if (IS_ERR(name)) + return PTR_ERR(name); + error = path_mountpoint(dfd, name, path, flags | LOOKUP_RCU); + if (unlikely(error == -ECHILD)) + error = path_mountpoint(dfd, name, path, flags); + if (unlikely(error == -ESTALE)) + error = path_mountpoint(dfd, name, path, flags | LOOKUP_REVAL); + if (likely(!error)) + audit_inode(name, path->dentry, 0); + putname(name); + return error; +} + +/** + * user_path_mountpoint_at - lookup a path from userland in order to umount it + * @dfd: directory file descriptor + * @name: pathname from userland + * @flags: lookup flags + * @path: pointer to container to hold result + * + * A umount is a special case for path walking. We're not actually interested + * in the inode in this situation, and ESTALE errors can be a problem. We + * simply want track down the dentry and vfsmount attached at the mountpoint + * and avoid revalidating the last component. + * + * Returns 0 and populates "path" on success. + */ +int +user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, + struct path *path) +{ + return filename_mountpoint(dfd, getname(name), path, flags); +} + +int +kern_path_mountpoint(int dfd, const char *name, struct path *path, + unsigned int flags) +{ + return filename_mountpoint(dfd, getname_kernel(name), path, flags); +} +EXPORT_SYMBOL(kern_path_mountpoint); + +int __check_sticky(struct inode *dir, struct inode *inode) +{ + kuid_t fsuid = current_fsuid(); + + if (uid_eq(inode->i_uid, fsuid)) + return 0; + if (uid_eq(dir->i_uid, fsuid)) + return 0; + return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); +} +EXPORT_SYMBOL(__check_sticky); + +/* + * Check whether we can remove a link victim from directory dir, check + * whether the type of victim is right. + * 1. We can't do it if dir is read-only (done in permission()) + * 2. We should have write and exec permissions on dir + * 3. We can't remove anything from append-only dir + * 4. We can't do anything with immutable dir (done in permission()) + * 5. If the sticky bit on dir is set we should either + * a. be owner of dir, or + * b. be owner of victim, or + * c. have CAP_FOWNER capability + * 6. If the victim is append-only or immutable we can't do antyhing with + * links pointing to it. + * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. + * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. + * 9. We can't remove a root or mountpoint. + * 10. We don't allow removal of NFS sillyrenamed files; it's handled by + * nfs_async_unlink(). + */ +static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) +{ + struct inode *inode = victim->d_inode; + int error; + + if (d_is_negative(victim)) + return -ENOENT; + BUG_ON(!inode); + + BUG_ON(victim->d_parent->d_inode != dir); + audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); + + error = inode_permission(dir, MAY_WRITE | MAY_EXEC); + if (error) + return error; + if (IS_APPEND(dir)) + return -EPERM; + + if (check_sticky(dir, inode) || IS_APPEND(inode) || + IS_IMMUTABLE(inode) || IS_SWAPFILE(inode)) + return -EPERM; + if (isdir) { + if (!d_is_dir(victim)) + return -ENOTDIR; + if (IS_ROOT(victim)) + return -EBUSY; + } else if (d_is_dir(victim)) + return -EISDIR; + if (IS_DEADDIR(dir)) + return -ENOENT; + if (victim->d_flags & DCACHE_NFSFS_RENAMED) + return -EBUSY; + return 0; +} + +/* Check whether we can create an object with dentry child in directory + * dir. + * 1. We can't do it if child already exists (open has special treatment for + * this case, but since we are inlined it's OK) + * 2. We can't do it if dir is read-only (done in permission()) + * 3. We should have write and exec permissions on dir + * 4. We can't do it if dir is immutable (done in permission()) + */ +static inline int may_create(struct inode *dir, struct dentry *child) +{ + audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); + if (child->d_inode) + return -EEXIST; + if (IS_DEADDIR(dir)) + return -ENOENT; + return inode_permission(dir, MAY_WRITE | MAY_EXEC); +} + +/* + * p1 and p2 should be directories on the same fs. + */ +struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) +{ + struct dentry *p; + + if (p1 == p2) { + mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); + return NULL; + } + + mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); + + p = d_ancestor(p2, p1); + if (p) { + mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); + mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); + return p; + } + + p = d_ancestor(p1, p2); + if (p) { + mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); + mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); + return p; + } + + mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); + mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT2); + return NULL; +} +EXPORT_SYMBOL(lock_rename); + +void unlock_rename(struct dentry *p1, struct dentry *p2) +{ + mutex_unlock(&p1->d_inode->i_mutex); + if (p1 != p2) { + mutex_unlock(&p2->d_inode->i_mutex); + mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); + } +} +EXPORT_SYMBOL(unlock_rename); + +int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, + bool want_excl) +{ + int error = may_create(dir, dentry); + if (error) + return error; + + if (!dir->i_op->create) + return -EACCES; /* shouldn't it be ENOSYS? */ + mode &= S_IALLUGO; + mode |= S_IFREG; + error = security_inode_create(dir, dentry, mode); + if (error) + return error; + error = dir->i_op->create(dir, dentry, mode, want_excl); + if (!error) + fsnotify_create(dir, dentry); + return error; +} +EXPORT_SYMBOL(vfs_create); + +static int may_open(struct path *path, int acc_mode, int flag) +{ + struct dentry *dentry = path->dentry; + struct inode *inode = dentry->d_inode; + int error; + + /* O_PATH? */ + if (!acc_mode) + return 0; + + if (!inode) + return -ENOENT; + + switch (inode->i_mode & S_IFMT) { + case S_IFLNK: + return -ELOOP; + case S_IFDIR: + if (acc_mode & MAY_WRITE) + return -EISDIR; + break; + case S_IFBLK: + case S_IFCHR: + if (path->mnt->mnt_flags & MNT_NODEV) + return -EACCES; + /*FALLTHRU*/ + case S_IFIFO: + case S_IFSOCK: + flag &= ~O_TRUNC; + break; + } + + error = inode_permission(inode, acc_mode); + if (error) + return error; + + /* + * An append-only file must be opened in append mode for writing. + */ + if (IS_APPEND(inode)) { + if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) + return -EPERM; + if (flag & O_TRUNC) + return -EPERM; + } + + /* O_NOATIME can only be set by the owner or superuser */ + if (flag & O_NOATIME && !inode_owner_or_capable(inode)) + return -EPERM; + + return 0; +} + +static int handle_truncate(struct file *filp) +{ + struct path *path = &filp->f_path; + struct inode *inode = path->dentry->d_inode; + int error = get_write_access(inode); + if (error) + return error; + /* + * Refuse to truncate files with mandatory locks held on them. + */ + error = locks_verify_locked(filp); + if (!error) + error = security_path_truncate(path); + if (!error) { + error = do_truncate(path->dentry, 0, + ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, + filp); + } + put_write_access(inode); + return error; +} + +static inline int open_to_namei_flags(int flag) +{ + if ((flag & O_ACCMODE) == 3) + flag--; + return flag; +} + +static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) +{ + int error = security_path_mknod(dir, dentry, mode, 0); + if (error) + return error; + + error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); + if (error) + return error; + + return security_inode_create(dir->dentry->d_inode, dentry, mode); +} + +/* + * Attempt to atomically look up, create and open a file from a negative + * dentry. + * + * Returns 0 if successful. The file will have been created and attached to + * @file by the filesystem calling finish_open(). + * + * Returns 1 if the file was looked up only or didn't need creating. The + * caller will need to perform the open themselves. @path will have been + * updated to point to the new dentry. This may be negative. + * + * Returns an error code otherwise. + */ +static int atomic_open(struct nameidata *nd, struct dentry *dentry, + struct path *path, struct file *file, + const struct open_flags *op, + bool got_write, bool need_lookup, + int *opened) +{ + struct inode *dir = nd->path.dentry->d_inode; + unsigned open_flag = open_to_namei_flags(op->open_flag); + umode_t mode; + int error; + int acc_mode; + int create_error = 0; + struct dentry *const DENTRY_NOT_SET = (void *) -1UL; + bool excl; + + BUG_ON(dentry->d_inode); + + /* Don't create child dentry for a dead directory. */ + if (unlikely(IS_DEADDIR(dir))) { + error = -ENOENT; + goto out; + } + + mode = op->mode; + if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) + mode &= ~current_umask(); + + excl = (open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT); + if (excl) + open_flag &= ~O_TRUNC; + + /* + * Checking write permission is tricky, bacuse we don't know if we are + * going to actually need it: O_CREAT opens should work as long as the + * file exists. But checking existence breaks atomicity. The trick is + * to check access and if not granted clear O_CREAT from the flags. + * + * Another problem is returing the "right" error value (e.g. for an + * O_EXCL open we want to return EEXIST not EROFS). + */ + if (((open_flag & (O_CREAT | O_TRUNC)) || + (open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) { + if (!(open_flag & O_CREAT)) { + /* + * No O_CREATE -> atomicity not a requirement -> fall + * back to lookup + open + */ + goto no_open; + } else if (open_flag & (O_EXCL | O_TRUNC)) { + /* Fall back and fail with the right error */ + create_error = -EROFS; + goto no_open; + } else { + /* No side effects, safe to clear O_CREAT */ + create_error = -EROFS; + open_flag &= ~O_CREAT; + } + } + + if (open_flag & O_CREAT) { + error = may_o_create(&nd->path, dentry, mode); + if (error) { + create_error = error; + if (open_flag & O_EXCL) + goto no_open; + open_flag &= ~O_CREAT; + } + } + + if (nd->flags & LOOKUP_DIRECTORY) + open_flag |= O_DIRECTORY; + + file->f_path.dentry = DENTRY_NOT_SET; + file->f_path.mnt = nd->path.mnt; + error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode, + opened); + if (error < 0) { + if (create_error && error == -ENOENT) + error = create_error; + goto out; + } + + if (error) { /* returned 1, that is */ + if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { + error = -EIO; + goto out; + } + if (file->f_path.dentry) { + dput(dentry); + dentry = file->f_path.dentry; + } + if (*opened & FILE_CREATED) + fsnotify_create(dir, dentry); + if (!dentry->d_inode) { + WARN_ON(*opened & FILE_CREATED); + if (create_error) { + error = create_error; + goto out; + } + } else { + if (excl && !(*opened & FILE_CREATED)) { + error = -EEXIST; + goto out; + } + } + goto looked_up; + } + + /* + * We didn't have the inode before the open, so check open permission + * here. + */ + acc_mode = op->acc_mode; + if (*opened & FILE_CREATED) { + WARN_ON(!(open_flag & O_CREAT)); + fsnotify_create(dir, dentry); + acc_mode = MAY_OPEN; + } + error = may_open(&file->f_path, acc_mode, open_flag); + if (error) + fput(file); + +out: + dput(dentry); + return error; + +no_open: + if (need_lookup) { + dentry = lookup_real(dir, dentry, nd->flags); + if (IS_ERR(dentry)) + return PTR_ERR(dentry); + + if (create_error) { + int open_flag = op->open_flag; + + error = create_error; + if ((open_flag & O_EXCL)) { + if (!dentry->d_inode) + goto out; + } else if (!dentry->d_inode) { + goto out; + } else if ((open_flag & O_TRUNC) && + d_is_reg(dentry)) { + goto out; + } + /* will fail later, go on to get the right error */ + } + } +looked_up: + path->dentry = dentry; + path->mnt = nd->path.mnt; + return 1; +} + +/* + * Look up and maybe create and open the last component. + * + * Must be called with i_mutex held on parent. + * + * Returns 0 if the file was successfully atomically created (if necessary) and + * opened. In this case the file will be returned attached to @file. + * + * Returns 1 if the file was not completely opened at this time, though lookups + * and creations will have been performed and the dentry returned in @path will + * be positive upon return if O_CREAT was specified. If O_CREAT wasn't + * specified then a negative dentry may be returned. + * + * An error code is returned otherwise. + * + * FILE_CREATE will be set in @*opened if the dentry was created and will be + * cleared otherwise prior to returning. + */ +static int lookup_open(struct nameidata *nd, struct path *path, + struct file *file, + const struct open_flags *op, + bool got_write, int *opened) +{ + struct dentry *dir = nd->path.dentry; + struct inode *dir_inode = dir->d_inode; + struct dentry *dentry; + int error; + bool need_lookup; + + *opened &= ~FILE_CREATED; + dentry = lookup_dcache(&nd->last, dir, nd->flags, &need_lookup); + if (IS_ERR(dentry)) + return PTR_ERR(dentry); + + /* Cached positive dentry: will open in f_op->open */ + if (!need_lookup && dentry->d_inode) + goto out_no_open; + + if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { + return atomic_open(nd, dentry, path, file, op, got_write, + need_lookup, opened); + } + + if (need_lookup) { + BUG_ON(dentry->d_inode); + + dentry = lookup_real(dir_inode, dentry, nd->flags); + if (IS_ERR(dentry)) + return PTR_ERR(dentry); + } + + /* Negative dentry, just create the file */ + if (!dentry->d_inode && (op->open_flag & O_CREAT)) { + umode_t mode = op->mode; + if (!IS_POSIXACL(dir->d_inode)) + mode &= ~current_umask(); + /* + * This write is needed to ensure that a + * rw->ro transition does not occur between + * the time when the file is created and when + * a permanent write count is taken through + * the 'struct file' in finish_open(). + */ + if (!got_write) { + error = -EROFS; + goto out_dput; + } + *opened |= FILE_CREATED; + error = security_path_mknod(&nd->path, dentry, mode, 0); + if (error) + goto out_dput; + error = vfs_create(dir->d_inode, dentry, mode, + nd->flags & LOOKUP_EXCL); + if (error) + goto out_dput; + } +out_no_open: + path->dentry = dentry; + path->mnt = nd->path.mnt; + return 1; + +out_dput: + dput(dentry); + return error; +} + +/* + * Handle the last step of open() + */ +static int do_last(struct nameidata *nd, struct path *path, + struct file *file, const struct open_flags *op, + int *opened, struct filename *name) +{ + struct dentry *dir = nd->path.dentry; + int open_flag = op->open_flag; + bool will_truncate = (open_flag & O_TRUNC) != 0; + bool got_write = false; + int acc_mode = op->acc_mode; + struct inode *inode; + bool symlink_ok = false; + struct path save_parent = { .dentry = NULL, .mnt = NULL }; + bool retried = false; + int error; + + nd->flags &= ~LOOKUP_PARENT; + nd->flags |= op->intent; + + if (nd->last_type != LAST_NORM) { + error = handle_dots(nd, nd->last_type); + if (error) + return error; + goto finish_open; + } + + if (!(open_flag & O_CREAT)) { + if (nd->last.name[nd->last.len]) + nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; + if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW)) + symlink_ok = true; + /* we _can_ be in RCU mode here */ + error = lookup_fast(nd, path, &inode); + if (likely(!error)) + goto finish_lookup; + + if (error < 0) + goto out; + + BUG_ON(nd->inode != dir->d_inode); + } else { + /* create side of things */ + /* + * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED + * has been cleared when we got to the last component we are + * about to look up + */ + error = complete_walk(nd); + if (error) + return error; + + audit_inode(name, dir, LOOKUP_PARENT); + error = -EISDIR; + /* trailing slashes? */ + if (nd->last.name[nd->last.len]) + goto out; + } + +retry_lookup: + if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { + error = mnt_want_write(nd->path.mnt); + if (!error) + got_write = true; + /* + * do _not_ fail yet - we might not need that or fail with + * a different error; let lookup_open() decide; we'll be + * dropping this one anyway. + */ + } + mutex_lock(&dir->d_inode->i_mutex); + error = lookup_open(nd, path, file, op, got_write, opened); + mutex_unlock(&dir->d_inode->i_mutex); + + if (error <= 0) { + if (error) + goto out; + + if ((*opened & FILE_CREATED) || + !S_ISREG(file_inode(file)->i_mode)) + will_truncate = false; + + audit_inode(name, file->f_path.dentry, 0); + goto opened; + } + + if (*opened & FILE_CREATED) { + /* Don't check for write permission, don't truncate */ + open_flag &= ~O_TRUNC; + will_truncate = false; + acc_mode = MAY_OPEN; + path_to_nameidata(path, nd); + goto finish_open_created; + } + + /* + * create/update audit record if it already exists. + */ + if (d_is_positive(path->dentry)) + audit_inode(name, path->dentry, 0); + + /* + * If atomic_open() acquired write access it is dropped now due to + * possible mount and symlink following (this might be optimized away if + * necessary...) + */ + if (got_write) { + mnt_drop_write(nd->path.mnt); + got_write = false; + } + + error = -EEXIST; + if ((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT)) + goto exit_dput; + + error = follow_managed(path, nd->flags); + if (error < 0) + goto exit_dput; + + if (error) + nd->flags |= LOOKUP_JUMPED; + + BUG_ON(nd->flags & LOOKUP_RCU); + inode = path->dentry->d_inode; + error = -ENOENT; + if (d_is_negative(path->dentry)) { + path_to_nameidata(path, nd); + goto out; + } +finish_lookup: + /* we _can_ be in RCU mode here */ + if (should_follow_link(path->dentry, !symlink_ok)) { + if (nd->flags & LOOKUP_RCU) { + if (unlikely(nd->path.mnt != path->mnt || + unlazy_walk(nd, path->dentry))) { + error = -ECHILD; + goto out; + } + } + BUG_ON(inode != path->dentry->d_inode); + return 1; + } + + if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path->mnt) { + path_to_nameidata(path, nd); + } else { + save_parent.dentry = nd->path.dentry; + save_parent.mnt = mntget(path->mnt); + nd->path.dentry = path->dentry; + + } + nd->inode = inode; + /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ +finish_open: + error = complete_walk(nd); + if (error) { + path_put(&save_parent); + return error; + } + audit_inode(name, nd->path.dentry, 0); + error = -EISDIR; + if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) + goto out; + error = -ENOTDIR; + if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) + goto out; + if (!d_is_reg(nd->path.dentry)) + will_truncate = false; + + if (will_truncate) { + error = mnt_want_write(nd->path.mnt); + if (error) + goto out; + got_write = true; + } +finish_open_created: + error = may_open(&nd->path, acc_mode, open_flag); + if (error) + goto out; + + BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ + error = vfs_open(&nd->path, file, current_cred()); + if (!error) { + *opened |= FILE_OPENED; + } else { + if (error == -EOPENSTALE) + goto stale_open; + goto out; + } +opened: + error = open_check_o_direct(file); + if (error) + goto exit_fput; + error = ima_file_check(file, op->acc_mode, *opened); + if (error) + goto exit_fput; + + if (will_truncate) { + error = handle_truncate(file); + if (error) + goto exit_fput; + } +out: + if (got_write) + mnt_drop_write(nd->path.mnt); + path_put(&save_parent); + terminate_walk(nd); + return error; + +exit_dput: + path_put_conditional(path, nd); + goto out; +exit_fput: + fput(file); + goto out; + +stale_open: + /* If no saved parent or already retried then can't retry */ + if (!save_parent.dentry || retried) + goto out; + + BUG_ON(save_parent.dentry != dir); + path_put(&nd->path); + nd->path = save_parent; + nd->inode = dir->d_inode; + save_parent.mnt = NULL; + save_parent.dentry = NULL; + if (got_write) { + mnt_drop_write(nd->path.mnt); + got_write = false; + } + retried = true; + goto retry_lookup; +} + +static int do_tmpfile(int dfd, struct filename *pathname, + struct nameidata *nd, int flags, + const struct open_flags *op, + struct file *file, int *opened) +{ + static const struct qstr name = QSTR_INIT("/", 1); + struct dentry *dentry, *child; + struct inode *dir; + int error = path_lookupat(dfd, pathname, + flags | LOOKUP_DIRECTORY, nd); + if (unlikely(error)) + return error; + error = mnt_want_write(nd->path.mnt); + if (unlikely(error)) + goto out; + /* we want directory to be writable */ + error = inode_permission(nd->inode, MAY_WRITE | MAY_EXEC); + if (error) + goto out2; + dentry = nd->path.dentry; + dir = dentry->d_inode; + if (!dir->i_op->tmpfile) { + error = -EOPNOTSUPP; + goto out2; + } + child = d_alloc(dentry, &name); + if (unlikely(!child)) { + error = -ENOMEM; + goto out2; + } + nd->flags &= ~LOOKUP_DIRECTORY; + nd->flags |= op->intent; + dput(nd->path.dentry); + nd->path.dentry = child; + error = dir->i_op->tmpfile(dir, nd->path.dentry, op->mode); + if (error) + goto out2; + audit_inode(pathname, nd->path.dentry, 0); + /* Don't check for other permissions, the inode was just created */ + error = may_open(&nd->path, MAY_OPEN, op->open_flag); + if (error) + goto out2; + file->f_path.mnt = nd->path.mnt; + error = finish_open(file, nd->path.dentry, NULL, opened); + if (error) + goto out2; + error = open_check_o_direct(file); + if (error) { + fput(file); + } else if (!(op->open_flag & O_EXCL)) { + struct inode *inode = file_inode(file); + spin_lock(&inode->i_lock); + inode->i_state |= I_LINKABLE; + spin_unlock(&inode->i_lock); + } +out2: + mnt_drop_write(nd->path.mnt); +out: + path_put(&nd->path); + return error; +} + +static struct file *path_openat(int dfd, struct filename *pathname, + struct nameidata *nd, const struct open_flags *op, int flags) +{ + struct file *file; + struct path path; + int opened = 0; + int error; + + file = get_empty_filp(); + if (IS_ERR(file)) + return file; + + file->f_flags = op->open_flag; + + if (unlikely(file->f_flags & __O_TMPFILE)) { + error = do_tmpfile(dfd, pathname, nd, flags, op, file, &opened); + goto out2; + } + + error = path_init(dfd, pathname, flags, nd); + if (unlikely(error)) + goto out; + + error = do_last(nd, &path, file, op, &opened, pathname); + while (unlikely(error > 0)) { /* trailing symlink */ + struct path link = path; + void *cookie; + if (!(nd->flags & LOOKUP_FOLLOW)) { + path_put_conditional(&path, nd); + path_put(&nd->path); + error = -ELOOP; + break; + } + error = may_follow_link(&link, nd); + if (unlikely(error)) + break; + nd->flags |= LOOKUP_PARENT; + nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); + error = follow_link(&link, nd, &cookie); + if (unlikely(error)) + break; + error = do_last(nd, &path, file, op, &opened, pathname); + put_link(nd, &link, cookie); + } +out: + path_cleanup(nd); +out2: + if (!(opened & FILE_OPENED)) { + BUG_ON(!error); + put_filp(file); + } + if (unlikely(error)) { + if (error == -EOPENSTALE) { + if (flags & LOOKUP_RCU) + error = -ECHILD; + else + error = -ESTALE; + } + file = ERR_PTR(error); + } + return file; +} + +struct file *do_filp_open(int dfd, struct filename *pathname, + const struct open_flags *op) +{ + struct nameidata nd; + int flags = op->lookup_flags; + struct file *filp; + + filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); + if (unlikely(filp == ERR_PTR(-ECHILD))) + filp = path_openat(dfd, pathname, &nd, op, flags); + if (unlikely(filp == ERR_PTR(-ESTALE))) + filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); + return filp; +} + +struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, + const char *name, const struct open_flags *op) +{ + struct nameidata nd; + struct file *file; + struct filename *filename; + int flags = op->lookup_flags | LOOKUP_ROOT; + + nd.root.mnt = mnt; + nd.root.dentry = dentry; + + if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) + return ERR_PTR(-ELOOP); + + filename = getname_kernel(name); + if (unlikely(IS_ERR(filename))) + return ERR_CAST(filename); + + file = path_openat(-1, filename, &nd, op, flags | LOOKUP_RCU); + if (unlikely(file == ERR_PTR(-ECHILD))) + file = path_openat(-1, filename, &nd, op, flags); + if (unlikely(file == ERR_PTR(-ESTALE))) + file = path_openat(-1, filename, &nd, op, flags | LOOKUP_REVAL); + putname(filename); + return file; +} + +static struct dentry *filename_create(int dfd, struct filename *name, + struct path *path, unsigned int lookup_flags) +{ + struct dentry *dentry = ERR_PTR(-EEXIST); + struct nameidata nd; + int err2; + int error; + bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); + + /* + * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any + * other flags passed in are ignored! + */ + lookup_flags &= LOOKUP_REVAL; + + error = filename_lookup(dfd, name, LOOKUP_PARENT|lookup_flags, &nd); + if (error) + return ERR_PTR(error); + + /* + * Yucky last component or no last component at all? + * (foo/., foo/.., /////) + */ + if (nd.last_type != LAST_NORM) + goto out; + nd.flags &= ~LOOKUP_PARENT; + nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; + + /* don't fail immediately if it's r/o, at least try to report other errors */ + err2 = mnt_want_write(nd.path.mnt); + /* + * Do the final lookup. + */ + mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); + dentry = lookup_hash(&nd); + if (IS_ERR(dentry)) + goto unlock; + + error = -EEXIST; + if (d_is_positive(dentry)) + goto fail; + + /* + * Special case - lookup gave negative, but... we had foo/bar/ + * From the vfs_mknod() POV we just have a negative dentry - + * all is fine. Let's be bastards - you had / on the end, you've + * been asking for (non-existent) directory. -ENOENT for you. + */ + if (unlikely(!is_dir && nd.last.name[nd.last.len])) { + error = -ENOENT; + goto fail; + } + if (unlikely(err2)) { + error = err2; + goto fail; + } + *path = nd.path; + return dentry; +fail: + dput(dentry); + dentry = ERR_PTR(error); +unlock: + mutex_unlock(&nd.path.dentry->d_inode->i_mutex); + if (!err2) + mnt_drop_write(nd.path.mnt); +out: + path_put(&nd.path); + return dentry; +} + +struct dentry *kern_path_create(int dfd, const char *pathname, + struct path *path, unsigned int lookup_flags) +{ + struct filename *filename = getname_kernel(pathname); + struct dentry *res; + + if (IS_ERR(filename)) + return ERR_CAST(filename); + res = filename_create(dfd, filename, path, lookup_flags); + putname(filename); + return res; +} +EXPORT_SYMBOL(kern_path_create); + +void done_path_create(struct path *path, struct dentry *dentry) +{ + dput(dentry); + mutex_unlock(&path->dentry->d_inode->i_mutex); + mnt_drop_write(path->mnt); + path_put(path); +} +EXPORT_SYMBOL(done_path_create); + +struct dentry *user_path_create(int dfd, const char __user *pathname, + struct path *path, unsigned int lookup_flags) +{ + struct filename *tmp = getname(pathname); + struct dentry *res; + if (IS_ERR(tmp)) + return ERR_CAST(tmp); + res = filename_create(dfd, tmp, path, lookup_flags); + putname(tmp); + return res; +} +EXPORT_SYMBOL(user_path_create); + +int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) +{ + int error = may_create(dir, dentry); + + if (error) + return error; + + if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) + return -EPERM; + + if (!dir->i_op->mknod) + return -EPERM; + + error = devcgroup_inode_mknod(mode, dev); + if (error) + return error; + + error = security_inode_mknod(dir, dentry, mode, dev); + if (error) + return error; + + error = dir->i_op->mknod(dir, dentry, mode, dev); + if (!error) + fsnotify_create(dir, dentry); + return error; +} +EXPORT_SYMBOL(vfs_mknod); + +static int may_mknod(umode_t mode) +{ + switch (mode & S_IFMT) { + case S_IFREG: + case S_IFCHR: + case S_IFBLK: + case S_IFIFO: + case S_IFSOCK: + case 0: /* zero mode translates to S_IFREG */ + return 0; + case S_IFDIR: + return -EPERM; + default: + return -EINVAL; + } +} + +SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, + unsigned, dev) +{ + struct dentry *dentry; + struct path path; + int error; + unsigned int lookup_flags = 0; + + error = may_mknod(mode); + if (error) + return error; +retry: + dentry = user_path_create(dfd, filename, &path, lookup_flags); + if (IS_ERR(dentry)) + return PTR_ERR(dentry); + + if (!IS_POSIXACL(path.dentry->d_inode)) + mode &= ~current_umask(); + error = security_path_mknod(&path, dentry, mode, dev); + if (error) + goto out; + switch (mode & S_IFMT) { + case 0: case S_IFREG: + error = vfs_create(path.dentry->d_inode,dentry,mode,true); + break; + case S_IFCHR: case S_IFBLK: + error = vfs_mknod(path.dentry->d_inode,dentry,mode, + new_decode_dev(dev)); + break; + case S_IFIFO: case S_IFSOCK: + error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); + break; + } +out: + done_path_create(&path, dentry); + if (retry_estale(error, lookup_flags)) { + lookup_flags |= LOOKUP_REVAL; + goto retry; + } + return error; +} + +SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) +{ + return sys_mknodat(AT_FDCWD, filename, mode, dev); +} + +int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) +{ + int error = may_create(dir, dentry); + unsigned max_links = dir->i_sb->s_max_links; + + if (error) + return error; + + if (!dir->i_op->mkdir) + return -EPERM; + + mode &= (S_IRWXUGO|S_ISVTX); + error = security_inode_mkdir(dir, dentry, mode); + if (error) + return error; + + if (max_links && dir->i_nlink >= max_links) + return -EMLINK; + + error = dir->i_op->mkdir(dir, dentry, mode); + if (!error) + fsnotify_mkdir(dir, dentry); + return error; +} +EXPORT_SYMBOL(vfs_mkdir); + +SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) +{ + struct dentry *dentry; + struct path path; + int error; + unsigned int lookup_flags = LOOKUP_DIRECTORY; + +retry: + dentry = user_path_create(dfd, pathname, &path, lookup_flags); + if (IS_ERR(dentry)) + return PTR_ERR(dentry); + + if (!IS_POSIXACL(path.dentry->d_inode)) + mode &= ~current_umask(); + error = security_path_mkdir(&path, dentry, mode); + if (!error) + error = vfs_mkdir(path.dentry->d_inode, dentry, mode); + done_path_create(&path, dentry); + if (retry_estale(error, lookup_flags)) { + lookup_flags |= LOOKUP_REVAL; + goto retry; + } + return error; +} + +SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) +{ + return sys_mkdirat(AT_FDCWD, pathname, mode); +} + +/* + * The dentry_unhash() helper will try to drop the dentry early: we + * should have a usage count of 1 if we're the only user of this + * dentry, and if that is true (possibly after pruning the dcache), + * then we drop the dentry now. + * + * A low-level filesystem can, if it choses, legally + * do a + * + * if (!d_unhashed(dentry)) + * return -EBUSY; + * + * if it cannot handle the case of removing a directory + * that is still in use by something else.. + */ +void dentry_unhash(struct dentry *dentry) +{ + shrink_dcache_parent(dentry); + spin_lock(&dentry->d_lock); + if (dentry->d_lockref.count == 1) + __d_drop(dentry); + spin_unlock(&dentry->d_lock); +} +EXPORT_SYMBOL(dentry_unhash); + +int vfs_rmdir(struct inode *dir, struct dentry *dentry) +{ + int error = may_delete(dir, dentry, 1); + + if (error) + return error; + + if (!dir->i_op->rmdir) + return -EPERM; + + dget(dentry); + mutex_lock(&dentry->d_inode->i_mutex); + + error = -EBUSY; + if (is_local_mountpoint(dentry)) + goto out; + + error = security_inode_rmdir(dir, dentry); + if (error) + goto out; + + shrink_dcache_parent(dentry); + error = dir->i_op->rmdir(dir, dentry); + if (error) + goto out; + + dentry->d_inode->i_flags |= S_DEAD; + dont_mount(dentry); + detach_mounts(dentry); + +out: + mutex_unlock(&dentry->d_inode->i_mutex); + dput(dentry); + if (!error) + d_delete(dentry); + return error; +} +EXPORT_SYMBOL(vfs_rmdir); + +static long do_rmdir(int dfd, const char __user *pathname) +{ + int error = 0; + struct filename *name; + struct dentry *dentry; + struct nameidata nd; + unsigned int lookup_flags = 0; +retry: + name = user_path_parent(dfd, pathname, &nd, lookup_flags); + if (IS_ERR(name)) + return PTR_ERR(name); + + switch(nd.last_type) { + case LAST_DOTDOT: + error = -ENOTEMPTY; + goto exit1; + case LAST_DOT: + error = -EINVAL; + goto exit1; + case LAST_ROOT: + error = -EBUSY; + goto exit1; + } + + nd.flags &= ~LOOKUP_PARENT; + error = mnt_want_write(nd.path.mnt); + if (error) + goto exit1; + + mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); + dentry = lookup_hash(&nd); + error = PTR_ERR(dentry); + if (IS_ERR(dentry)) + goto exit2; + if (!dentry->d_inode) { + error = -ENOENT; + goto exit3; + } + error = security_path_rmdir(&nd.path, dentry); + if (error) + goto exit3; + error = vfs_rmdir(nd.path.dentry->d_inode, dentry); +exit3: + dput(dentry); +exit2: + mutex_unlock(&nd.path.dentry->d_inode->i_mutex); + mnt_drop_write(nd.path.mnt); +exit1: + path_put(&nd.path); + putname(name); + if (retry_estale(error, lookup_flags)) { + lookup_flags |= LOOKUP_REVAL; + goto retry; + } + return error; +} + +SYSCALL_DEFINE1(rmdir, const char __user *, pathname) +{ + return do_rmdir(AT_FDCWD, pathname); +} + +/** + * vfs_unlink - unlink a filesystem object + * @dir: parent directory + * @dentry: victim + * @delegated_inode: returns victim inode, if the inode is delegated. + * + * The caller must hold dir->i_mutex. + * + * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and + * return a reference to the inode in delegated_inode. The caller + * should then break the delegation on that inode and retry. Because + * breaking a delegation may take a long time, the caller should drop + * dir->i_mutex before doing so. + * + * Alternatively, a caller may pass NULL for delegated_inode. This may + * be appropriate for callers that expect the underlying filesystem not + * to be NFS exported. + */ +int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) +{ + struct inode *target = dentry->d_inode; + int error = may_delete(dir, dentry, 0); + + if (error) + return error; + + if (!dir->i_op->unlink) + return -EPERM; + + mutex_lock(&target->i_mutex); + if (is_local_mountpoint(dentry)) + error = -EBUSY; + else { + error = security_inode_unlink(dir, dentry); + if (!error) { + error = try_break_deleg(target, delegated_inode); + if (error) + goto out; + error = dir->i_op->unlink(dir, dentry); + if (!error) { + dont_mount(dentry); + detach_mounts(dentry); + } + } + } +out: + mutex_unlock(&target->i_mutex); + + /* We don't d_delete() NFS sillyrenamed files--they still exist. */ + if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { + fsnotify_link_count(target); + d_delete(dentry); + } + + return error; +} +EXPORT_SYMBOL(vfs_unlink); + +/* + * Make sure that the actual truncation of the file will occur outside its + * directory's i_mutex. Truncate can take a long time if there is a lot of + * writeout happening, and we don't want to prevent access to the directory + * while waiting on the I/O. + */ +static long do_unlinkat(int dfd, const char __user *pathname) +{ + int error; + struct filename *name; + struct dentry *dentry; + struct nameidata nd; + struct inode *inode = NULL; + struct inode *delegated_inode = NULL; + unsigned int lookup_flags = 0; +retry: + name = user_path_parent(dfd, pathname, &nd, lookup_flags); + if (IS_ERR(name)) + return PTR_ERR(name); + + error = -EISDIR; + if (nd.last_type != LAST_NORM) + goto exit1; + + nd.flags &= ~LOOKUP_PARENT; + error = mnt_want_write(nd.path.mnt); + if (error) + goto exit1; +retry_deleg: + mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); + dentry = lookup_hash(&nd); + error = PTR_ERR(dentry); + if (!IS_ERR(dentry)) { + /* Why not before? Because we want correct error value */ + if (nd.last.name[nd.last.len]) + goto slashes; + inode = dentry->d_inode; + if (d_is_negative(dentry)) + goto slashes; + ihold(inode); + error = security_path_unlink(&nd.path, dentry); + if (error) + goto exit2; + error = vfs_unlink(nd.path.dentry->d_inode, dentry, &delegated_inode); +exit2: + dput(dentry); + } + mutex_unlock(&nd.path.dentry->d_inode->i_mutex); + if (inode) + iput(inode); /* truncate the inode here */ + inode = NULL; + if (delegated_inode) { + error = break_deleg_wait(&delegated_inode); + if (!error) + goto retry_deleg; + } + mnt_drop_write(nd.path.mnt); +exit1: + path_put(&nd.path); + putname(name); + if (retry_estale(error, lookup_flags)) { + lookup_flags |= LOOKUP_REVAL; + inode = NULL; + goto retry; + } + return error; + +slashes: + if (d_is_negative(dentry)) + error = -ENOENT; + else if (d_is_dir(dentry)) + error = -EISDIR; + else + error = -ENOTDIR; + goto exit2; +} + +SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) +{ + if ((flag & ~AT_REMOVEDIR) != 0) + return -EINVAL; + + if (flag & AT_REMOVEDIR) + return do_rmdir(dfd, pathname); + + return do_unlinkat(dfd, pathname); +} + +SYSCALL_DEFINE1(unlink, const char __user *, pathname) +{ + return do_unlinkat(AT_FDCWD, pathname); +} + +int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) +{ + int error = may_create(dir, dentry); + + if (error) + return error; + + if (!dir->i_op->symlink) + return -EPERM; + + error = security_inode_symlink(dir, dentry, oldname); + if (error) + return error; + + error = dir->i_op->symlink(dir, dentry, oldname); + if (!error) + fsnotify_create(dir, dentry); + return error; +} +EXPORT_SYMBOL(vfs_symlink); + +SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, + int, newdfd, const char __user *, newname) +{ + int error; + struct filename *from; + struct dentry *dentry; + struct path path; + unsigned int lookup_flags = 0; + + from = getname(oldname); + if (IS_ERR(from)) + return PTR_ERR(from); +retry: + dentry = user_path_create(newdfd, newname, &path, lookup_flags); + error = PTR_ERR(dentry); + if (IS_ERR(dentry)) + goto out_putname; + + error = security_path_symlink(&path, dentry, from->name); + if (!error) + error = vfs_symlink(path.dentry->d_inode, dentry, from->name); + done_path_create(&path, dentry); + if (retry_estale(error, lookup_flags)) { + lookup_flags |= LOOKUP_REVAL; + goto retry; + } +out_putname: + putname(from); + return error; +} + +SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) +{ + return sys_symlinkat(oldname, AT_FDCWD, newname); +} + +/** + * vfs_link - create a new link + * @old_dentry: object to be linked + * @dir: new parent + * @new_dentry: where to create the new link + * @delegated_inode: returns inode needing a delegation break + * + * The caller must hold dir->i_mutex + * + * If vfs_link discovers a delegation on the to-be-linked file in need + * of breaking, it will return -EWOULDBLOCK and return a reference to the + * inode in delegated_inode. The caller should then break the delegation + * and retry. Because breaking a delegation may take a long time, the + * caller should drop the i_mutex before doing so. + * + * Alternatively, a caller may pass NULL for delegated_inode. This may + * be appropriate for callers that expect the underlying filesystem not + * to be NFS exported. + */ +int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) +{ + struct inode *inode = old_dentry->d_inode; + unsigned max_links = dir->i_sb->s_max_links; + int error; + + if (!inode) + return -ENOENT; + + error = may_create(dir, new_dentry); + if (error) + return error; + + if (dir->i_sb != inode->i_sb) + return -EXDEV; + + /* + * A link to an append-only or immutable file cannot be created. + */ + if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) + return -EPERM; + if (!dir->i_op->link) + return -EPERM; + if (S_ISDIR(inode->i_mode)) + return -EPERM; + + error = security_inode_link(old_dentry, dir, new_dentry); + if (error) + return error; + + mutex_lock(&inode->i_mutex); + /* Make sure we don't allow creating hardlink to an unlinked file */ + if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) + error = -ENOENT; + else if (max_links && inode->i_nlink >= max_links) + error = -EMLINK; + else { + error = try_break_deleg(inode, delegated_inode); + if (!error) + error = dir->i_op->link(old_dentry, dir, new_dentry); + } + + if (!error && (inode->i_state & I_LINKABLE)) { + spin_lock(&inode->i_lock); + inode->i_state &= ~I_LINKABLE; + spin_unlock(&inode->i_lock); + } + mutex_unlock(&inode->i_mutex); + if (!error) + fsnotify_link(dir, inode, new_dentry); + return error; +} +EXPORT_SYMBOL(vfs_link); + +/* + * Hardlinks are often used in delicate situations. We avoid + * security-related surprises by not following symlinks on the + * newname. --KAB + * + * We don't follow them on the oldname either to be compatible + * with linux 2.0, and to avoid hard-linking to directories + * and other special files. --ADM + */ +SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, + int, newdfd, const char __user *, newname, int, flags) +{ + struct dentry *new_dentry; + struct path old_path, new_path; + struct inode *delegated_inode = NULL; + int how = 0; + int error; + + if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) + return -EINVAL; + /* + * To use null names we require CAP_DAC_READ_SEARCH + * This ensures that not everyone will be able to create + * handlink using the passed filedescriptor. + */ + if (flags & AT_EMPTY_PATH) { + if (!capable(CAP_DAC_READ_SEARCH)) + return -ENOENT; + how = LOOKUP_EMPTY; + } + + if (flags & AT_SYMLINK_FOLLOW) + how |= LOOKUP_FOLLOW; +retry: + error = user_path_at(olddfd, oldname, how, &old_path); + if (error) + return error; + + new_dentry = user_path_create(newdfd, newname, &new_path, + (how & LOOKUP_REVAL)); + error = PTR_ERR(new_dentry); + if (IS_ERR(new_dentry)) + goto out; + + error = -EXDEV; + if (old_path.mnt != new_path.mnt) + goto out_dput; + error = may_linkat(&old_path); + if (unlikely(error)) + goto out_dput; + error = security_path_link(old_path.dentry, &new_path, new_dentry); + if (error) + goto out_dput; + error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); +out_dput: + done_path_create(&new_path, new_dentry); + if (delegated_inode) { + error = break_deleg_wait(&delegated_inode); + if (!error) { + path_put(&old_path); + goto retry; + } + } + if (retry_estale(error, how)) { + path_put(&old_path); + how |= LOOKUP_REVAL; + goto retry; + } +out: + path_put(&old_path); + + return error; +} + +SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) +{ + return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); +} + +/** + * vfs_rename - rename a filesystem object + * @old_dir: parent of source + * @old_dentry: source + * @new_dir: parent of destination + * @new_dentry: destination + * @delegated_inode: returns an inode needing a delegation break + * @flags: rename flags + * + * The caller must hold multiple mutexes--see lock_rename()). + * + * If vfs_rename discovers a delegation in need of breaking at either + * the source or destination, it will return -EWOULDBLOCK and return a + * reference to the inode in delegated_inode. The caller should then + * break the delegation and retry. Because breaking a delegation may + * take a long time, the caller should drop all locks before doing + * so. + * + * Alternatively, a caller may pass NULL for delegated_inode. This may + * be appropriate for callers that expect the underlying filesystem not + * to be NFS exported. + * + * The worst of all namespace operations - renaming directory. "Perverted" + * doesn't even start to describe it. Somebody in UCB had a heck of a trip... + * Problems: + * a) we can get into loop creation. + * b) race potential - two innocent renames can create a loop together. + * That's where 4.4 screws up. Current fix: serialization on + * sb->s_vfs_rename_mutex. We might be more accurate, but that's another + * story. + * c) we have to lock _four_ objects - parents and victim (if it exists), + * and source (if it is not a directory). + * And that - after we got ->i_mutex on parents (until then we don't know + * whether the target exists). Solution: try to be smart with locking + * order for inodes. We rely on the fact that tree topology may change + * only under ->s_vfs_rename_mutex _and_ that parent of the object we + * move will be locked. Thus we can rank directories by the tree + * (ancestors first) and rank all non-directories after them. + * That works since everybody except rename does "lock parent, lookup, + * lock child" and rename is under ->s_vfs_rename_mutex. + * HOWEVER, it relies on the assumption that any object with ->lookup() + * has no more than 1 dentry. If "hybrid" objects will ever appear, + * we'd better make sure that there's no link(2) for them. + * d) conversion from fhandle to dentry may come in the wrong moment - when + * we are removing the target. Solution: we will have to grab ->i_mutex + * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on + * ->i_mutex on parents, which works but leads to some truly excessive + * locking]. + */ +int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, + struct inode *new_dir, struct dentry *new_dentry, + struct inode **delegated_inode, unsigned int flags) +{ + int error; + bool is_dir = d_is_dir(old_dentry); + const unsigned char *old_name; + struct inode *source = old_dentry->d_inode; + struct inode *target = new_dentry->d_inode; + bool new_is_dir = false; + unsigned max_links = new_dir->i_sb->s_max_links; + + if (source == target) + return 0; + + error = may_delete(old_dir, old_dentry, is_dir); + if (error) + return error; + + if (!target) { + error = may_create(new_dir, new_dentry); + } else { + new_is_dir = d_is_dir(new_dentry); + + if (!(flags & RENAME_EXCHANGE)) + error = may_delete(new_dir, new_dentry, is_dir); + else + error = may_delete(new_dir, new_dentry, new_is_dir); + } + if (error) + return error; + + if (!old_dir->i_op->rename && !old_dir->i_op->rename2) + return -EPERM; + + if (flags && !old_dir->i_op->rename2) + return -EINVAL; + + /* + * If we are going to change the parent - check write permissions, + * we'll need to flip '..'. + */ + if (new_dir != old_dir) { + if (is_dir) { + error = inode_permission(source, MAY_WRITE); + if (error) + return error; + } + if ((flags & RENAME_EXCHANGE) && new_is_dir) { + error = inode_permission(target, MAY_WRITE); + if (error) + return error; + } + } + + error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, + flags); + if (error) + return error; + + old_name = fsnotify_oldname_init(old_dentry->d_name.name); + dget(new_dentry); + if (!is_dir || (flags & RENAME_EXCHANGE)) + lock_two_nondirectories(source, target); + else if (target) + mutex_lock(&target->i_mutex); + + error = -EBUSY; + if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) + goto out; + + if (max_links && new_dir != old_dir) { + error = -EMLINK; + if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) + goto out; + if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && + old_dir->i_nlink >= max_links) + goto out; + } + if (is_dir && !(flags & RENAME_EXCHANGE) && target) + shrink_dcache_parent(new_dentry); + if (!is_dir) { + error = try_break_deleg(source, delegated_inode); + if (error) + goto out; + } + if (target && !new_is_dir) { + error = try_break_deleg(target, delegated_inode); + if (error) + goto out; + } + if (!old_dir->i_op->rename2) { + error = old_dir->i_op->rename(old_dir, old_dentry, + new_dir, new_dentry); + } else { + WARN_ON(old_dir->i_op->rename != NULL); + error = old_dir->i_op->rename2(old_dir, old_dentry, + new_dir, new_dentry, flags); + } + if (error) + goto out; + + if (!(flags & RENAME_EXCHANGE) && target) { + if (is_dir) + target->i_flags |= S_DEAD; + dont_mount(new_dentry); + detach_mounts(new_dentry); + } + if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { + if (!(flags & RENAME_EXCHANGE)) + d_move(old_dentry, new_dentry); + else + d_exchange(old_dentry, new_dentry); + } +out: + if (!is_dir || (flags & RENAME_EXCHANGE)) + unlock_two_nondirectories(source, target); + else if (target) + mutex_unlock(&target->i_mutex); + dput(new_dentry); + if (!error) { + fsnotify_move(old_dir, new_dir, old_name, is_dir, + !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); + if (flags & RENAME_EXCHANGE) { + fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, + new_is_dir, NULL, new_dentry); + } + } + fsnotify_oldname_free(old_name); + + return error; +} +EXPORT_SYMBOL(vfs_rename); + +SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, + int, newdfd, const char __user *, newname, unsigned int, flags) +{ + struct dentry *old_dir, *new_dir; + struct dentry *old_dentry, *new_dentry; + struct dentry *trap; + struct nameidata oldnd, newnd; + struct inode *delegated_inode = NULL; + struct filename *from; + struct filename *to; + unsigned int lookup_flags = 0; + bool should_retry = false; + int error; + + if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) + return -EINVAL; + + if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && + (flags & RENAME_EXCHANGE)) + return -EINVAL; + + if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) + return -EPERM; + +retry: + from = user_path_parent(olddfd, oldname, &oldnd, lookup_flags); + if (IS_ERR(from)) { + error = PTR_ERR(from); + goto exit; + } + + to = user_path_parent(newdfd, newname, &newnd, lookup_flags); + if (IS_ERR(to)) { + error = PTR_ERR(to); + goto exit1; + } + + error = -EXDEV; + if (oldnd.path.mnt != newnd.path.mnt) + goto exit2; + + old_dir = oldnd.path.dentry; + error = -EBUSY; + if (oldnd.last_type != LAST_NORM) + goto exit2; + + new_dir = newnd.path.dentry; + if (flags & RENAME_NOREPLACE) + error = -EEXIST; + if (newnd.last_type != LAST_NORM) + goto exit2; + + error = mnt_want_write(oldnd.path.mnt); + if (error) + goto exit2; + + oldnd.flags &= ~LOOKUP_PARENT; + newnd.flags &= ~LOOKUP_PARENT; + if (!(flags & RENAME_EXCHANGE)) + newnd.flags |= LOOKUP_RENAME_TARGET; + +retry_deleg: + trap = lock_rename(new_dir, old_dir); + + old_dentry = lookup_hash(&oldnd); + error = PTR_ERR(old_dentry); + if (IS_ERR(old_dentry)) + goto exit3; + /* source must exist */ + error = -ENOENT; + if (d_is_negative(old_dentry)) + goto exit4; + new_dentry = lookup_hash(&newnd); + error = PTR_ERR(new_dentry); + if (IS_ERR(new_dentry)) + goto exit4; + error = -EEXIST; + if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) + goto exit5; + if (flags & RENAME_EXCHANGE) { + error = -ENOENT; + if (d_is_negative(new_dentry)) + goto exit5; + + if (!d_is_dir(new_dentry)) { + error = -ENOTDIR; + if (newnd.last.name[newnd.last.len]) + goto exit5; + } + } + /* unless the source is a directory trailing slashes give -ENOTDIR */ + if (!d_is_dir(old_dentry)) { + error = -ENOTDIR; + if (oldnd.last.name[oldnd.last.len]) + goto exit5; + if (!(flags & RENAME_EXCHANGE) && newnd.last.name[newnd.last.len]) + goto exit5; + } + /* source should not be ancestor of target */ + error = -EINVAL; + if (old_dentry == trap) + goto exit5; + /* target should not be an ancestor of source */ + if (!(flags & RENAME_EXCHANGE)) + error = -ENOTEMPTY; + if (new_dentry == trap) + goto exit5; + + error = security_path_rename(&oldnd.path, old_dentry, + &newnd.path, new_dentry, flags); + if (error) + goto exit5; + error = vfs_rename(old_dir->d_inode, old_dentry, + new_dir->d_inode, new_dentry, + &delegated_inode, flags); +exit5: + dput(new_dentry); +exit4: + dput(old_dentry); +exit3: + unlock_rename(new_dir, old_dir); + if (delegated_inode) { + error = break_deleg_wait(&delegated_inode); + if (!error) + goto retry_deleg; + } + mnt_drop_write(oldnd.path.mnt); +exit2: + if (retry_estale(error, lookup_flags)) + should_retry = true; + path_put(&newnd.path); + putname(to); +exit1: + path_put(&oldnd.path); + putname(from); + if (should_retry) { + should_retry = false; + lookup_flags |= LOOKUP_REVAL; + goto retry; + } +exit: + return error; +} + +SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, + int, newdfd, const char __user *, newname) +{ + return sys_renameat2(olddfd, oldname, newdfd, newname, 0); +} + +SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) +{ + return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); +} + +int vfs_whiteout(struct inode *dir, struct dentry *dentry) +{ + int error = may_create(dir, dentry); + if (error) + return error; + + if (!dir->i_op->mknod) + return -EPERM; + + return dir->i_op->mknod(dir, dentry, + S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); +} +EXPORT_SYMBOL(vfs_whiteout); + +int readlink_copy(char __user *buffer, int buflen, const char *link) +{ + int len = PTR_ERR(link); + if (IS_ERR(link)) + goto out; + + len = strlen(link); + if (len > (unsigned) buflen) + len = buflen; + if (copy_to_user(buffer, link, len)) + len = -EFAULT; +out: + return len; +} +EXPORT_SYMBOL(readlink_copy); + +/* + * A helper for ->readlink(). This should be used *ONLY* for symlinks that + * have ->follow_link() touching nd only in nd_set_link(). Using (or not + * using) it for any given inode is up to filesystem. + */ +int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) +{ + struct nameidata nd; + void *cookie; + int res; + + nd.depth = 0; + cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); + if (IS_ERR(cookie)) + return PTR_ERR(cookie); + + res = readlink_copy(buffer, buflen, nd_get_link(&nd)); + if (dentry->d_inode->i_op->put_link) + dentry->d_inode->i_op->put_link(dentry, &nd, cookie); + return res; +} +EXPORT_SYMBOL(generic_readlink); + +/* get the link contents into pagecache */ +static char *page_getlink(struct dentry * dentry, struct page **ppage) +{ + char *kaddr; + struct page *page; + struct address_space *mapping = dentry->d_inode->i_mapping; + page = read_mapping_page(mapping, 0, NULL); + if (IS_ERR(page)) + return (char*)page; + *ppage = page; + kaddr = kmap(page); + nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); + return kaddr; +} + +int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) +{ + struct page *page = NULL; + int res = readlink_copy(buffer, buflen, page_getlink(dentry, &page)); + if (page) { + kunmap(page); + page_cache_release(page); + } + return res; +} +EXPORT_SYMBOL(page_readlink); + +void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) +{ + struct page *page = NULL; + nd_set_link(nd, page_getlink(dentry, &page)); + return page; +} +EXPORT_SYMBOL(page_follow_link_light); + +void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) +{ + struct page *page = cookie; + + if (page) { + kunmap(page); + page_cache_release(page); + } +} +EXPORT_SYMBOL(page_put_link); + +/* + * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS + */ +int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) +{ + struct address_space *mapping = inode->i_mapping; + struct page *page; + void *fsdata; + int err; + char *kaddr; + unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; + if (nofs) + flags |= AOP_FLAG_NOFS; + +retry: + err = pagecache_write_begin(NULL, mapping, 0, len-1, + flags, &page, &fsdata); + if (err) + goto fail; + + kaddr = kmap_atomic(page); + memcpy(kaddr, symname, len-1); + kunmap_atomic(kaddr); + + err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, + page, fsdata); + if (err < 0) + goto fail; + if (err < len-1) + goto retry; + + mark_inode_dirty(inode); + return 0; +fail: + return err; +} +EXPORT_SYMBOL(__page_symlink); + +int page_symlink(struct inode *inode, const char *symname, int len) +{ + return __page_symlink(inode, symname, len, + !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); +} +EXPORT_SYMBOL(page_symlink); + +const struct inode_operations page_symlink_inode_operations = { + .readlink = generic_readlink, + .follow_link = page_follow_link_light, + .put_link = page_put_link, +}; +EXPORT_SYMBOL(page_symlink_inode_operations); |