diff options
Diffstat (limited to 'fs/open.c')
| -rw-r--r-- | fs/open.c | 1149 |
1 files changed, 1149 insertions, 0 deletions
diff --git a/fs/open.c b/fs/open.c new file mode 100644 index 000000000..9d175dbea --- /dev/null +++ b/fs/open.c @@ -0,0 +1,1149 @@ +/* + * linux/fs/open.c + * + * Copyright (C) 1991, 1992 Linus Torvalds + */ + +#include <linux/string.h> +#include <linux/mm.h> +#include <linux/file.h> +#include <linux/fdtable.h> +#include <linux/fsnotify.h> +#include <linux/module.h> +#include <linux/tty.h> +#include <linux/namei.h> +#include <linux/backing-dev.h> +#include <linux/capability.h> +#include <linux/securebits.h> +#include <linux/security.h> +#include <linux/mount.h> +#include <linux/fcntl.h> +#include <linux/slab.h> +#include <asm/uaccess.h> +#include <linux/fs.h> +#include <linux/personality.h> +#include <linux/pagemap.h> +#include <linux/syscalls.h> +#include <linux/rcupdate.h> +#include <linux/audit.h> +#include <linux/falloc.h> +#include <linux/fs_struct.h> +#include <linux/ima.h> +#include <linux/dnotify.h> +#include <linux/compat.h> + +#include "internal.h" + +#define CREATE_TRACE_POINTS +#include <trace/events/fs.h> + +int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs, + struct file *filp) +{ + int ret; + struct iattr newattrs; + + /* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */ + if (length < 0) + return -EINVAL; + + newattrs.ia_size = length; + newattrs.ia_valid = ATTR_SIZE | time_attrs; + if (filp) { + newattrs.ia_file = filp; + newattrs.ia_valid |= ATTR_FILE; + } + + /* Remove suid/sgid on truncate too */ + ret = should_remove_suid(dentry); + if (ret) + newattrs.ia_valid |= ret | ATTR_FORCE; + + mutex_lock(&dentry->d_inode->i_mutex); + /* Note any delegations or leases have already been broken: */ + ret = notify_change(dentry, &newattrs, NULL); + mutex_unlock(&dentry->d_inode->i_mutex); + return ret; +} +EXPORT_SYMBOL(do_truncate); + +long vfs_truncate(struct path *path, loff_t length) +{ + struct inode *inode; + long error; + + inode = path->dentry->d_inode; + + /* For directories it's -EISDIR, for other non-regulars - -EINVAL */ + if (S_ISDIR(inode->i_mode)) + return -EISDIR; + if (!S_ISREG(inode->i_mode)) + return -EINVAL; + + error = mnt_want_write(path->mnt); + if (error) + goto out; + + error = inode_permission(inode, MAY_WRITE); + if (error) + goto mnt_drop_write_and_out; + + error = -EPERM; + if (IS_APPEND(inode)) + goto mnt_drop_write_and_out; + + error = get_write_access(inode); + if (error) + goto mnt_drop_write_and_out; + + /* + * Make sure that there are no leases. get_write_access() protects + * against the truncate racing with a lease-granting setlease(). + */ + error = break_lease(inode, O_WRONLY); + if (error) + goto put_write_and_out; + + error = locks_verify_truncate(inode, NULL, length); + if (!error) + error = security_path_truncate(path); + if (!error) + error = do_truncate(path->dentry, length, 0, NULL); + +put_write_and_out: + put_write_access(inode); +mnt_drop_write_and_out: + mnt_drop_write(path->mnt); +out: + return error; +} +EXPORT_SYMBOL_GPL(vfs_truncate); + +static long do_sys_truncate(const char __user *pathname, loff_t length) +{ + unsigned int lookup_flags = LOOKUP_FOLLOW; + struct path path; + int error; + + if (length < 0) /* sorry, but loff_t says... */ + return -EINVAL; + +retry: + error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path); + if (!error) { + error = vfs_truncate(&path, length); + path_put(&path); + } + if (retry_estale(error, lookup_flags)) { + lookup_flags |= LOOKUP_REVAL; + goto retry; + } + return error; +} + +SYSCALL_DEFINE2(truncate, const char __user *, path, long, length) +{ + return do_sys_truncate(path, length); +} + +#ifdef CONFIG_COMPAT +COMPAT_SYSCALL_DEFINE2(truncate, const char __user *, path, compat_off_t, length) +{ + return do_sys_truncate(path, length); +} +#endif + +static long do_sys_ftruncate(unsigned int fd, loff_t length, int small) +{ + struct inode *inode; + struct dentry *dentry; + struct fd f; + int error; + + error = -EINVAL; + if (length < 0) + goto out; + error = -EBADF; + f = fdget(fd); + if (!f.file) + goto out; + + /* explicitly opened as large or we are on 64-bit box */ + if (f.file->f_flags & O_LARGEFILE) + small = 0; + + dentry = f.file->f_path.dentry; + inode = dentry->d_inode; + error = -EINVAL; + if (!S_ISREG(inode->i_mode) || !(f.file->f_mode & FMODE_WRITE)) + goto out_putf; + + error = -EINVAL; + /* Cannot ftruncate over 2^31 bytes without large file support */ + if (small && length > MAX_NON_LFS) + goto out_putf; + + error = -EPERM; + if (IS_APPEND(inode)) + goto out_putf; + + sb_start_write(inode->i_sb); + error = locks_verify_truncate(inode, f.file, length); + if (!error) + error = security_path_truncate(&f.file->f_path); + if (!error) + error = do_truncate(dentry, length, ATTR_MTIME|ATTR_CTIME, f.file); + sb_end_write(inode->i_sb); +out_putf: + fdput(f); +out: + return error; +} + +SYSCALL_DEFINE2(ftruncate, unsigned int, fd, unsigned long, length) +{ + return do_sys_ftruncate(fd, length, 1); +} + +#ifdef CONFIG_COMPAT +COMPAT_SYSCALL_DEFINE2(ftruncate, unsigned int, fd, compat_ulong_t, length) +{ + return do_sys_ftruncate(fd, length, 1); +} +#endif + +/* LFS versions of truncate are only needed on 32 bit machines */ +#if BITS_PER_LONG == 32 +SYSCALL_DEFINE2(truncate64, const char __user *, path, loff_t, length) +{ + return do_sys_truncate(path, length); +} + +SYSCALL_DEFINE2(ftruncate64, unsigned int, fd, loff_t, length) +{ + return do_sys_ftruncate(fd, length, 0); +} +#endif /* BITS_PER_LONG == 32 */ + + +int vfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len) +{ + struct inode *inode = file_inode(file); + long ret; + + if (offset < 0 || len <= 0) + return -EINVAL; + + /* Return error if mode is not supported */ + if (mode & ~FALLOC_FL_SUPPORTED_MASK) + return -EOPNOTSUPP; + + /* Punch hole and zero range are mutually exclusive */ + if ((mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE)) == + (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE)) + return -EOPNOTSUPP; + + /* Punch hole must have keep size set */ + if ((mode & FALLOC_FL_PUNCH_HOLE) && + !(mode & FALLOC_FL_KEEP_SIZE)) + return -EOPNOTSUPP; + + /* Collapse range should only be used exclusively. */ + if ((mode & FALLOC_FL_COLLAPSE_RANGE) && + (mode & ~FALLOC_FL_COLLAPSE_RANGE)) + return -EINVAL; + + /* Insert range should only be used exclusively. */ + if ((mode & FALLOC_FL_INSERT_RANGE) && + (mode & ~FALLOC_FL_INSERT_RANGE)) + return -EINVAL; + + if (!(file->f_mode & FMODE_WRITE)) + return -EBADF; + + /* + * We can only allow pure fallocate on append only files + */ + if ((mode & ~FALLOC_FL_KEEP_SIZE) && IS_APPEND(inode)) + return -EPERM; + + if (IS_IMMUTABLE(inode)) + return -EPERM; + + /* + * We cannot allow any fallocate operation on an active swapfile + */ + if (IS_SWAPFILE(inode)) + return -ETXTBSY; + + /* + * Revalidate the write permissions, in case security policy has + * changed since the files were opened. + */ + ret = security_file_permission(file, MAY_WRITE); + if (ret) + return ret; + + if (S_ISFIFO(inode->i_mode)) + return -ESPIPE; + + /* + * Let individual file system decide if it supports preallocation + * for directories or not. + */ + if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode)) + return -ENODEV; + + /* Check for wrap through zero too */ + if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0)) + return -EFBIG; + + if (!file->f_op->fallocate) + return -EOPNOTSUPP; + + sb_start_write(inode->i_sb); + ret = file->f_op->fallocate(file, mode, offset, len); + + /* + * Create inotify and fanotify events. + * + * To keep the logic simple always create events if fallocate succeeds. + * This implies that events are even created if the file size remains + * unchanged, e.g. when using flag FALLOC_FL_KEEP_SIZE. + */ + if (ret == 0) + fsnotify_modify(file); + + sb_end_write(inode->i_sb); + return ret; +} +EXPORT_SYMBOL_GPL(vfs_fallocate); + +SYSCALL_DEFINE4(fallocate, int, fd, int, mode, loff_t, offset, loff_t, len) +{ + struct fd f = fdget(fd); + int error = -EBADF; + + if (f.file) { + error = vfs_fallocate(f.file, mode, offset, len); + fdput(f); + } + return error; +} + +/* + * access() needs to use the real uid/gid, not the effective uid/gid. + * We do this by temporarily clearing all FS-related capabilities and + * switching the fsuid/fsgid around to the real ones. + */ +SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode) +{ + const struct cred *old_cred; + struct cred *override_cred; + struct path path; + struct inode *inode; + int res; + unsigned int lookup_flags = LOOKUP_FOLLOW; + + if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */ + return -EINVAL; + + override_cred = prepare_creds(); + if (!override_cred) + return -ENOMEM; + + override_cred->fsuid = override_cred->uid; + override_cred->fsgid = override_cred->gid; + + if (!issecure(SECURE_NO_SETUID_FIXUP)) { + /* Clear the capabilities if we switch to a non-root user */ + kuid_t root_uid = make_kuid(override_cred->user_ns, 0); + if (!uid_eq(override_cred->uid, root_uid)) + cap_clear(override_cred->cap_effective); + else + override_cred->cap_effective = + override_cred->cap_permitted; + } + + old_cred = override_creds(override_cred); +retry: + res = user_path_at(dfd, filename, lookup_flags, &path); + if (res) + goto out; + + inode = path.dentry->d_inode; + + if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) { + /* + * MAY_EXEC on regular files is denied if the fs is mounted + * with the "noexec" flag. + */ + res = -EACCES; + if (path.mnt->mnt_flags & MNT_NOEXEC) + goto out_path_release; + } + + res = inode_permission(inode, mode | MAY_ACCESS); + /* SuS v2 requires we report a read only fs too */ + if (res || !(mode & S_IWOTH) || special_file(inode->i_mode)) + goto out_path_release; + /* + * This is a rare case where using __mnt_is_readonly() + * is OK without a mnt_want/drop_write() pair. Since + * no actual write to the fs is performed here, we do + * not need to telegraph to that to anyone. + * + * By doing this, we accept that this access is + * inherently racy and know that the fs may change + * state before we even see this result. + */ + if (__mnt_is_readonly(path.mnt)) + res = -EROFS; + +out_path_release: + path_put(&path); + if (retry_estale(res, lookup_flags)) { + lookup_flags |= LOOKUP_REVAL; + goto retry; + } +out: + revert_creds(old_cred); + put_cred(override_cred); + return res; +} + +SYSCALL_DEFINE2(access, const char __user *, filename, int, mode) +{ + return sys_faccessat(AT_FDCWD, filename, mode); +} + +SYSCALL_DEFINE1(chdir, const char __user *, filename) +{ + struct path path; + int error; + unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY; +retry: + error = user_path_at(AT_FDCWD, filename, lookup_flags, &path); + if (error) + goto out; + + error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR); + if (error) + goto dput_and_out; + + set_fs_pwd(current->fs, &path); + +dput_and_out: + path_put(&path); + if (retry_estale(error, lookup_flags)) { + lookup_flags |= LOOKUP_REVAL; + goto retry; + } +out: + return error; +} + +SYSCALL_DEFINE1(fchdir, unsigned int, fd) +{ + struct fd f = fdget_raw(fd); + struct inode *inode; + int error = -EBADF; + + error = -EBADF; + if (!f.file) + goto out; + + inode = file_inode(f.file); + + error = -ENOTDIR; + if (!S_ISDIR(inode->i_mode)) + goto out_putf; + + error = inode_permission(inode, MAY_EXEC | MAY_CHDIR); + if (!error) + set_fs_pwd(current->fs, &f.file->f_path); +out_putf: + fdput(f); +out: + return error; +} + +SYSCALL_DEFINE1(chroot, const char __user *, filename) +{ + struct path path; + int error; + unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY; +retry: + error = user_path_at(AT_FDCWD, filename, lookup_flags, &path); + if (error) + goto out; + + error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR); + if (error) + goto dput_and_out; + + error = -EPERM; + if (!ns_capable(current_user_ns(), CAP_SYS_CHROOT)) + goto dput_and_out; + error = security_path_chroot(&path); + if (error) + goto dput_and_out; + + set_fs_root(current->fs, &path); + error = 0; +dput_and_out: + path_put(&path); + if (retry_estale(error, lookup_flags)) { + lookup_flags |= LOOKUP_REVAL; + goto retry; + } +out: + return error; +} + +static int chmod_common(struct path *path, umode_t mode) +{ + struct inode *inode = path->dentry->d_inode; + struct inode *delegated_inode = NULL; + struct iattr newattrs; + int error; + + error = mnt_want_write(path->mnt); + if (error) + return error; +retry_deleg: + mutex_lock(&inode->i_mutex); + error = security_path_chmod(path, mode); + if (error) + goto out_unlock; + newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO); + newattrs.ia_valid = ATTR_MODE | ATTR_CTIME; + error = notify_change(path->dentry, &newattrs, &delegated_inode); +out_unlock: + mutex_unlock(&inode->i_mutex); + if (delegated_inode) { + error = break_deleg_wait(&delegated_inode); + if (!error) + goto retry_deleg; + } + mnt_drop_write(path->mnt); + return error; +} + +SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode) +{ + struct fd f = fdget(fd); + int err = -EBADF; + + if (f.file) { + audit_file(f.file); + err = chmod_common(&f.file->f_path, mode); + fdput(f); + } + return err; +} + +SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename, umode_t, mode) +{ + struct path path; + int error; + unsigned int lookup_flags = LOOKUP_FOLLOW; +retry: + error = user_path_at(dfd, filename, lookup_flags, &path); + if (!error) { + error = chmod_common(&path, mode); + path_put(&path); + if (retry_estale(error, lookup_flags)) { + lookup_flags |= LOOKUP_REVAL; + goto retry; + } + } + return error; +} + +SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode) +{ + return sys_fchmodat(AT_FDCWD, filename, mode); +} + +static int chown_common(struct path *path, uid_t user, gid_t group) +{ + struct inode *inode = path->dentry->d_inode; + struct inode *delegated_inode = NULL; + int error; + struct iattr newattrs; + kuid_t uid; + kgid_t gid; + + uid = make_kuid(current_user_ns(), user); + gid = make_kgid(current_user_ns(), group); + +retry_deleg: + newattrs.ia_valid = ATTR_CTIME; + if (user != (uid_t) -1) { + if (!uid_valid(uid)) + return -EINVAL; + newattrs.ia_valid |= ATTR_UID; + newattrs.ia_uid = uid; + } + if (group != (gid_t) -1) { + if (!gid_valid(gid)) + return -EINVAL; + newattrs.ia_valid |= ATTR_GID; + newattrs.ia_gid = gid; + } + if (!S_ISDIR(inode->i_mode)) + newattrs.ia_valid |= + ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV; + mutex_lock(&inode->i_mutex); + error = security_path_chown(path, uid, gid); + if (!error) + error = notify_change(path->dentry, &newattrs, &delegated_inode); + mutex_unlock(&inode->i_mutex); + if (delegated_inode) { + error = break_deleg_wait(&delegated_inode); + if (!error) + goto retry_deleg; + } + return error; +} + +SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user, + gid_t, group, int, flag) +{ + struct path path; + int error = -EINVAL; + int lookup_flags; + + if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0) + goto out; + + lookup_flags = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW; + if (flag & AT_EMPTY_PATH) + lookup_flags |= LOOKUP_EMPTY; +retry: + error = user_path_at(dfd, filename, lookup_flags, &path); + if (error) + goto out; + error = mnt_want_write(path.mnt); + if (error) + goto out_release; + error = chown_common(&path, user, group); + mnt_drop_write(path.mnt); +out_release: + path_put(&path); + if (retry_estale(error, lookup_flags)) { + lookup_flags |= LOOKUP_REVAL; + goto retry; + } +out: + return error; +} + +SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group) +{ + return sys_fchownat(AT_FDCWD, filename, user, group, 0); +} + +SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group) +{ + return sys_fchownat(AT_FDCWD, filename, user, group, + AT_SYMLINK_NOFOLLOW); +} + +SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group) +{ + struct fd f = fdget(fd); + int error = -EBADF; + + if (!f.file) + goto out; + + error = mnt_want_write_file(f.file); + if (error) + goto out_fput; + audit_file(f.file); + error = chown_common(&f.file->f_path, user, group); + mnt_drop_write_file(f.file); +out_fput: + fdput(f); +out: + return error; +} + +int open_check_o_direct(struct file *f) +{ + /* NB: we're sure to have correct a_ops only after f_op->open */ + if (f->f_flags & O_DIRECT) { + if (!f->f_mapping->a_ops || !f->f_mapping->a_ops->direct_IO) + return -EINVAL; + } + return 0; +} +EXPORT_SYMBOL(open_check_o_direct); + +static int do_dentry_open(struct file *f, + int (*open)(struct inode *, struct file *), + const struct cred *cred) +{ + static const struct file_operations empty_fops = {}; + struct inode *inode; + int error; + + f->f_mode = OPEN_FMODE(f->f_flags) | FMODE_LSEEK | + FMODE_PREAD | FMODE_PWRITE; + + path_get(&f->f_path); + inode = f->f_inode = f->f_path.dentry->d_inode; + f->f_mapping = inode->i_mapping; + + if (unlikely(f->f_flags & O_PATH)) { + f->f_mode = FMODE_PATH; + f->f_op = &empty_fops; + return 0; + } + + if (f->f_mode & FMODE_WRITE && !special_file(inode->i_mode)) { + error = get_write_access(inode); + if (unlikely(error)) + goto cleanup_file; + error = __mnt_want_write(f->f_path.mnt); + if (unlikely(error)) { + put_write_access(inode); + goto cleanup_file; + } + f->f_mode |= FMODE_WRITER; + } + + /* POSIX.1-2008/SUSv4 Section XSI 2.9.7 */ + if (S_ISREG(inode->i_mode)) + f->f_mode |= FMODE_ATOMIC_POS; + + f->f_op = fops_get(inode->i_fop); + if (unlikely(WARN_ON(!f->f_op))) { + error = -ENODEV; + goto cleanup_all; + } + + error = security_file_open(f, cred); + if (error) + goto cleanup_all; + + error = break_lease(inode, f->f_flags); + if (error) + goto cleanup_all; + + if (!open) + open = f->f_op->open; + if (open) { + error = open(inode, f); + if (error) + goto cleanup_all; + } + if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ) + i_readcount_inc(inode); + if ((f->f_mode & FMODE_READ) && + likely(f->f_op->read || f->f_op->read_iter)) + f->f_mode |= FMODE_CAN_READ; + if ((f->f_mode & FMODE_WRITE) && + likely(f->f_op->write || f->f_op->write_iter)) + f->f_mode |= FMODE_CAN_WRITE; + + f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC); + + file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping); + + return 0; + +cleanup_all: + fops_put(f->f_op); + if (f->f_mode & FMODE_WRITER) { + put_write_access(inode); + __mnt_drop_write(f->f_path.mnt); + } +cleanup_file: + path_put(&f->f_path); + f->f_path.mnt = NULL; + f->f_path.dentry = NULL; + f->f_inode = NULL; + return error; +} + +/** + * finish_open - finish opening a file + * @file: file pointer + * @dentry: pointer to dentry + * @open: open callback + * @opened: state of open + * + * This can be used to finish opening a file passed to i_op->atomic_open(). + * + * If the open callback is set to NULL, then the standard f_op->open() + * filesystem callback is substituted. + * + * NB: the dentry reference is _not_ consumed. If, for example, the dentry is + * the return value of d_splice_alias(), then the caller needs to perform dput() + * on it after finish_open(). + * + * On successful return @file is a fully instantiated open file. After this, if + * an error occurs in ->atomic_open(), it needs to clean up with fput(). + * + * Returns zero on success or -errno if the open failed. + */ +int finish_open(struct file *file, struct dentry *dentry, + int (*open)(struct inode *, struct file *), + int *opened) +{ + int error; + BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ + + file->f_path.dentry = dentry; + error = do_dentry_open(file, open, current_cred()); + if (!error) + *opened |= FILE_OPENED; + + return error; +} +EXPORT_SYMBOL(finish_open); + +/** + * finish_no_open - finish ->atomic_open() without opening the file + * + * @file: file pointer + * @dentry: dentry or NULL (as returned from ->lookup()) + * + * This can be used to set the result of a successful lookup in ->atomic_open(). + * + * NB: unlike finish_open() this function does consume the dentry reference and + * the caller need not dput() it. + * + * Returns "1" which must be the return value of ->atomic_open() after having + * called this function. + */ +int finish_no_open(struct file *file, struct dentry *dentry) +{ + file->f_path.dentry = dentry; + return 1; +} +EXPORT_SYMBOL(finish_no_open); + +struct file *dentry_open(const struct path *path, int flags, + const struct cred *cred) +{ + int error; + struct file *f; + + validate_creds(cred); + + /* We must always pass in a valid mount pointer. */ + BUG_ON(!path->mnt); + + f = get_empty_filp(); + if (!IS_ERR(f)) { + f->f_flags = flags; + error = vfs_open(path, f, cred); + if (!error) { + /* from now on we need fput() to dispose of f */ + error = open_check_o_direct(f); + if (error) { + fput(f); + f = ERR_PTR(error); + } + } else { + put_filp(f); + f = ERR_PTR(error); + } + } + return f; +} +EXPORT_SYMBOL(dentry_open); + +/** + * vfs_open - open the file at the given path + * @path: path to open + * @filp: newly allocated file with f_flag initialized + * @cred: credentials to use + */ +int vfs_open(const struct path *path, struct file *filp, + const struct cred *cred) +{ + struct inode *inode = path->dentry->d_inode; + + if (inode->i_op->dentry_open) + return inode->i_op->dentry_open(path->dentry, filp, cred); + else { + filp->f_path = *path; + return do_dentry_open(filp, NULL, cred); + } +} +EXPORT_SYMBOL(vfs_open); + +static inline int build_open_flags(int flags, umode_t mode, struct open_flags *op) +{ + int lookup_flags = 0; + int acc_mode; + + if (flags & (O_CREAT | __O_TMPFILE)) + op->mode = (mode & S_IALLUGO) | S_IFREG; + else + op->mode = 0; + + /* Must never be set by userspace */ + flags &= ~FMODE_NONOTIFY & ~O_CLOEXEC; + + /* + * O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only + * check for O_DSYNC if the need any syncing at all we enforce it's + * always set instead of having to deal with possibly weird behaviour + * for malicious applications setting only __O_SYNC. + */ + if (flags & __O_SYNC) + flags |= O_DSYNC; + + if (flags & __O_TMPFILE) { + if ((flags & O_TMPFILE_MASK) != O_TMPFILE) + return -EINVAL; + acc_mode = MAY_OPEN | ACC_MODE(flags); + if (!(acc_mode & MAY_WRITE)) + return -EINVAL; + } else if (flags & O_PATH) { + /* + * If we have O_PATH in the open flag. Then we + * cannot have anything other than the below set of flags + */ + flags &= O_DIRECTORY | O_NOFOLLOW | O_PATH; + acc_mode = 0; + } else { + acc_mode = MAY_OPEN | ACC_MODE(flags); + } + + op->open_flag = flags; + + /* O_TRUNC implies we need access checks for write permissions */ + if (flags & O_TRUNC) + acc_mode |= MAY_WRITE; + + /* Allow the LSM permission hook to distinguish append + access from general write access. */ + if (flags & O_APPEND) + acc_mode |= MAY_APPEND; + + op->acc_mode = acc_mode; + + op->intent = flags & O_PATH ? 0 : LOOKUP_OPEN; + + if (flags & O_CREAT) { + op->intent |= LOOKUP_CREATE; + if (flags & O_EXCL) + op->intent |= LOOKUP_EXCL; + } + + if (flags & O_DIRECTORY) + lookup_flags |= LOOKUP_DIRECTORY; + if (!(flags & O_NOFOLLOW)) + lookup_flags |= LOOKUP_FOLLOW; + op->lookup_flags = lookup_flags; + return 0; +} + +/** + * file_open_name - open file and return file pointer + * + * @name: struct filename containing path to open + * @flags: open flags as per the open(2) second argument + * @mode: mode for the new file if O_CREAT is set, else ignored + * + * This is the helper to open a file from kernelspace if you really + * have to. But in generally you should not do this, so please move + * along, nothing to see here.. + */ +struct file *file_open_name(struct filename *name, int flags, umode_t mode) +{ + struct open_flags op; + int err = build_open_flags(flags, mode, &op); + return err ? ERR_PTR(err) : do_filp_open(AT_FDCWD, name, &op); +} + +/** + * filp_open - open file and return file pointer + * + * @filename: path to open + * @flags: open flags as per the open(2) second argument + * @mode: mode for the new file if O_CREAT is set, else ignored + * + * This is the helper to open a file from kernelspace if you really + * have to. But in generally you should not do this, so please move + * along, nothing to see here.. + */ +struct file *filp_open(const char *filename, int flags, umode_t mode) +{ + struct filename *name = getname_kernel(filename); + struct file *file = ERR_CAST(name); + + if (!IS_ERR(name)) { + file = file_open_name(name, flags, mode); + putname(name); + } + return file; +} +EXPORT_SYMBOL(filp_open); + +struct file *file_open_root(struct dentry *dentry, struct vfsmount *mnt, + const char *filename, int flags) +{ + struct open_flags op; + int err = build_open_flags(flags, 0, &op); + if (err) + return ERR_PTR(err); + if (flags & O_CREAT) + return ERR_PTR(-EINVAL); + return do_file_open_root(dentry, mnt, filename, &op); +} +EXPORT_SYMBOL(file_open_root); + +long do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode) +{ + struct open_flags op; + int fd = build_open_flags(flags, mode, &op); + struct filename *tmp; + + if (fd) + return fd; + + tmp = getname(filename); + if (IS_ERR(tmp)) + return PTR_ERR(tmp); + + fd = get_unused_fd_flags(flags); + if (fd >= 0) { + struct file *f = do_filp_open(dfd, tmp, &op); + if (IS_ERR(f)) { + put_unused_fd(fd); + fd = PTR_ERR(f); + } else { + fsnotify_open(f); + fd_install(fd, f); + trace_do_sys_open(tmp->name, flags, mode); + } + } + putname(tmp); + return fd; +} + +SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode) +{ + if (force_o_largefile()) + flags |= O_LARGEFILE; + + return do_sys_open(AT_FDCWD, filename, flags, mode); +} + +SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags, + umode_t, mode) +{ + if (force_o_largefile()) + flags |= O_LARGEFILE; + + return do_sys_open(dfd, filename, flags, mode); +} + +#ifndef __alpha__ + +/* + * For backward compatibility? Maybe this should be moved + * into arch/i386 instead? + */ +SYSCALL_DEFINE2(creat, const char __user *, pathname, umode_t, mode) +{ + return sys_open(pathname, O_CREAT | O_WRONLY | O_TRUNC, mode); +} + +#endif + +/* + * "id" is the POSIX thread ID. We use the + * files pointer for this.. + */ +int filp_close(struct file *filp, fl_owner_t id) +{ + int retval = 0; + + if (!file_count(filp)) { + printk(KERN_ERR "VFS: Close: file count is 0\n"); + return 0; + } + + if (filp->f_op->flush) + retval = filp->f_op->flush(filp, id); + + if (likely(!(filp->f_mode & FMODE_PATH))) { + dnotify_flush(filp, id); + locks_remove_posix(filp, id); + } + fput(filp); + return retval; +} + +EXPORT_SYMBOL(filp_close); + +/* + * Careful here! We test whether the file pointer is NULL before + * releasing the fd. This ensures that one clone task can't release + * an fd while another clone is opening it. + */ +SYSCALL_DEFINE1(close, unsigned int, fd) +{ + int retval = __close_fd(current->files, fd); + + /* can't restart close syscall because file table entry was cleared */ + if (unlikely(retval == -ERESTARTSYS || + retval == -ERESTARTNOINTR || + retval == -ERESTARTNOHAND || + retval == -ERESTART_RESTARTBLOCK)) + retval = -EINTR; + + return retval; +} +EXPORT_SYMBOL(sys_close); + +/* + * This routine simulates a hangup on the tty, to arrange that users + * are given clean terminals at login time. + */ +SYSCALL_DEFINE0(vhangup) +{ + if (capable(CAP_SYS_TTY_CONFIG)) { + tty_vhangup_self(); + return 0; + } + return -EPERM; +} + +/* + * Called when an inode is about to be open. + * We use this to disallow opening large files on 32bit systems if + * the caller didn't specify O_LARGEFILE. On 64bit systems we force + * on this flag in sys_open. + */ +int generic_file_open(struct inode * inode, struct file * filp) +{ + if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS) + return -EOVERFLOW; + return 0; +} + +EXPORT_SYMBOL(generic_file_open); + +/* + * This is used by subsystems that don't want seekable + * file descriptors. The function is not supposed to ever fail, the only + * reason it returns an 'int' and not 'void' is so that it can be plugged + * directly into file_operations structure. + */ +int nonseekable_open(struct inode *inode, struct file *filp) +{ + filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE); + return 0; +} + +EXPORT_SYMBOL(nonseekable_open); |