diff options
author | André Fabian Silva Delgado <emulatorman@parabola.nu> | 2015-08-05 17:04:01 -0300 |
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committer | André Fabian Silva Delgado <emulatorman@parabola.nu> | 2015-08-05 17:04:01 -0300 |
commit | 57f0f512b273f60d52568b8c6b77e17f5636edc0 (patch) | |
tree | 5e910f0e82173f4ef4f51111366a3f1299037a7b /fs/xattr.c |
Initial import
Diffstat (limited to 'fs/xattr.c')
-rw-r--r-- | fs/xattr.c | 973 |
1 files changed, 973 insertions, 0 deletions
diff --git a/fs/xattr.c b/fs/xattr.c new file mode 100644 index 000000000..6bb630399 --- /dev/null +++ b/fs/xattr.c @@ -0,0 +1,973 @@ +/* + File: fs/xattr.c + + Extended attribute handling. + + Copyright (C) 2001 by Andreas Gruenbacher <a.gruenbacher@computer.org> + Copyright (C) 2001 SGI - Silicon Graphics, Inc <linux-xfs@oss.sgi.com> + Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com> + */ +#include <linux/fs.h> +#include <linux/slab.h> +#include <linux/file.h> +#include <linux/xattr.h> +#include <linux/mount.h> +#include <linux/namei.h> +#include <linux/security.h> +#include <linux/evm.h> +#include <linux/syscalls.h> +#include <linux/export.h> +#include <linux/fsnotify.h> +#include <linux/audit.h> +#include <linux/vmalloc.h> +#include <linux/posix_acl_xattr.h> + +#include <asm/uaccess.h> + +/* + * Check permissions for extended attribute access. This is a bit complicated + * because different namespaces have very different rules. + */ +static int +xattr_permission(struct inode *inode, const char *name, int mask) +{ + /* + * We can never set or remove an extended attribute on a read-only + * filesystem or on an immutable / append-only inode. + */ + if (mask & MAY_WRITE) { + if (IS_IMMUTABLE(inode) || IS_APPEND(inode)) + return -EPERM; + } + + /* + * No restriction for security.* and system.* from the VFS. Decision + * on these is left to the underlying filesystem / security module. + */ + if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN) || + !strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) + return 0; + + /* + * The trusted.* namespace can only be accessed by privileged users. + */ + if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN)) { + if (!capable(CAP_SYS_ADMIN)) + return (mask & MAY_WRITE) ? -EPERM : -ENODATA; + return 0; + } + + /* + * In the user.* namespace, only regular files and directories can have + * extended attributes. For sticky directories, only the owner and + * privileged users can write attributes. + */ + if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN)) { + if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode)) + return (mask & MAY_WRITE) ? -EPERM : -ENODATA; + if (S_ISDIR(inode->i_mode) && (inode->i_mode & S_ISVTX) && + (mask & MAY_WRITE) && !inode_owner_or_capable(inode)) + return -EPERM; + } + + return inode_permission(inode, mask); +} + +/** + * __vfs_setxattr_noperm - perform setxattr operation without performing + * permission checks. + * + * @dentry - object to perform setxattr on + * @name - xattr name to set + * @value - value to set @name to + * @size - size of @value + * @flags - flags to pass into filesystem operations + * + * returns the result of the internal setxattr or setsecurity operations. + * + * This function requires the caller to lock the inode's i_mutex before it + * is executed. It also assumes that the caller will make the appropriate + * permission checks. + */ +int __vfs_setxattr_noperm(struct dentry *dentry, const char *name, + const void *value, size_t size, int flags) +{ + struct inode *inode = dentry->d_inode; + int error = -EOPNOTSUPP; + int issec = !strncmp(name, XATTR_SECURITY_PREFIX, + XATTR_SECURITY_PREFIX_LEN); + + if (issec) + inode->i_flags &= ~S_NOSEC; + if (inode->i_op->setxattr) { + error = inode->i_op->setxattr(dentry, name, value, size, flags); + if (!error) { + fsnotify_xattr(dentry); + security_inode_post_setxattr(dentry, name, value, + size, flags); + } + } else if (issec) { + const char *suffix = name + XATTR_SECURITY_PREFIX_LEN; + error = security_inode_setsecurity(inode, suffix, value, + size, flags); + if (!error) + fsnotify_xattr(dentry); + } + + return error; +} + + +int +vfs_setxattr(struct dentry *dentry, const char *name, const void *value, + size_t size, int flags) +{ + struct inode *inode = dentry->d_inode; + int error; + + error = xattr_permission(inode, name, MAY_WRITE); + if (error) + return error; + + mutex_lock(&inode->i_mutex); + error = security_inode_setxattr(dentry, name, value, size, flags); + if (error) + goto out; + + error = __vfs_setxattr_noperm(dentry, name, value, size, flags); + +out: + mutex_unlock(&inode->i_mutex); + return error; +} +EXPORT_SYMBOL_GPL(vfs_setxattr); + +ssize_t +xattr_getsecurity(struct inode *inode, const char *name, void *value, + size_t size) +{ + void *buffer = NULL; + ssize_t len; + + if (!value || !size) { + len = security_inode_getsecurity(inode, name, &buffer, false); + goto out_noalloc; + } + + len = security_inode_getsecurity(inode, name, &buffer, true); + if (len < 0) + return len; + if (size < len) { + len = -ERANGE; + goto out; + } + memcpy(value, buffer, len); +out: + security_release_secctx(buffer, len); +out_noalloc: + return len; +} +EXPORT_SYMBOL_GPL(xattr_getsecurity); + +/* + * vfs_getxattr_alloc - allocate memory, if necessary, before calling getxattr + * + * Allocate memory, if not already allocated, or re-allocate correct size, + * before retrieving the extended attribute. + * + * Returns the result of alloc, if failed, or the getxattr operation. + */ +ssize_t +vfs_getxattr_alloc(struct dentry *dentry, const char *name, char **xattr_value, + size_t xattr_size, gfp_t flags) +{ + struct inode *inode = dentry->d_inode; + char *value = *xattr_value; + int error; + + error = xattr_permission(inode, name, MAY_READ); + if (error) + return error; + + if (!inode->i_op->getxattr) + return -EOPNOTSUPP; + + error = inode->i_op->getxattr(dentry, name, NULL, 0); + if (error < 0) + return error; + + if (!value || (error > xattr_size)) { + value = krealloc(*xattr_value, error + 1, flags); + if (!value) + return -ENOMEM; + memset(value, 0, error + 1); + } + + error = inode->i_op->getxattr(dentry, name, value, error); + *xattr_value = value; + return error; +} +EXPORT_SYMBOL(vfs_getxattr_alloc); + +/* Compare an extended attribute value with the given value */ +int vfs_xattr_cmp(struct dentry *dentry, const char *xattr_name, + const char *value, size_t size, gfp_t flags) +{ + char *xattr_value = NULL; + int rc; + + rc = vfs_getxattr_alloc(dentry, xattr_name, &xattr_value, 0, flags); + if (rc < 0) + return rc; + + if ((rc != size) || (memcmp(xattr_value, value, rc) != 0)) + rc = -EINVAL; + else + rc = 0; + kfree(xattr_value); + return rc; +} + +ssize_t +vfs_getxattr(struct dentry *dentry, const char *name, void *value, size_t size) +{ + struct inode *inode = dentry->d_inode; + int error; + + error = xattr_permission(inode, name, MAY_READ); + if (error) + return error; + + error = security_inode_getxattr(dentry, name); + if (error) + return error; + + if (!strncmp(name, XATTR_SECURITY_PREFIX, + XATTR_SECURITY_PREFIX_LEN)) { + const char *suffix = name + XATTR_SECURITY_PREFIX_LEN; + int ret = xattr_getsecurity(inode, suffix, value, size); + /* + * Only overwrite the return value if a security module + * is actually active. + */ + if (ret == -EOPNOTSUPP) + goto nolsm; + return ret; + } +nolsm: + if (inode->i_op->getxattr) + error = inode->i_op->getxattr(dentry, name, value, size); + else + error = -EOPNOTSUPP; + + return error; +} +EXPORT_SYMBOL_GPL(vfs_getxattr); + +ssize_t +vfs_listxattr(struct dentry *d, char *list, size_t size) +{ + ssize_t error; + + error = security_inode_listxattr(d); + if (error) + return error; + error = -EOPNOTSUPP; + if (d->d_inode->i_op->listxattr) { + error = d->d_inode->i_op->listxattr(d, list, size); + } else { + error = security_inode_listsecurity(d->d_inode, list, size); + if (size && error > size) + error = -ERANGE; + } + return error; +} +EXPORT_SYMBOL_GPL(vfs_listxattr); + +int +vfs_removexattr(struct dentry *dentry, const char *name) +{ + struct inode *inode = dentry->d_inode; + int error; + + if (!inode->i_op->removexattr) + return -EOPNOTSUPP; + + error = xattr_permission(inode, name, MAY_WRITE); + if (error) + return error; + + mutex_lock(&inode->i_mutex); + error = security_inode_removexattr(dentry, name); + if (error) { + mutex_unlock(&inode->i_mutex); + return error; + } + + error = inode->i_op->removexattr(dentry, name); + mutex_unlock(&inode->i_mutex); + + if (!error) { + fsnotify_xattr(dentry); + evm_inode_post_removexattr(dentry, name); + } + return error; +} +EXPORT_SYMBOL_GPL(vfs_removexattr); + + +/* + * Extended attribute SET operations + */ +static long +setxattr(struct dentry *d, const char __user *name, const void __user *value, + size_t size, int flags) +{ + int error; + void *kvalue = NULL; + void *vvalue = NULL; /* If non-NULL, we used vmalloc() */ + char kname[XATTR_NAME_MAX + 1]; + + if (flags & ~(XATTR_CREATE|XATTR_REPLACE)) + return -EINVAL; + + error = strncpy_from_user(kname, name, sizeof(kname)); + if (error == 0 || error == sizeof(kname)) + error = -ERANGE; + if (error < 0) + return error; + + if (size) { + if (size > XATTR_SIZE_MAX) + return -E2BIG; + kvalue = kmalloc(size, GFP_KERNEL | __GFP_NOWARN); + if (!kvalue) { + vvalue = vmalloc(size); + if (!vvalue) + return -ENOMEM; + kvalue = vvalue; + } + if (copy_from_user(kvalue, value, size)) { + error = -EFAULT; + goto out; + } + if ((strcmp(kname, XATTR_NAME_POSIX_ACL_ACCESS) == 0) || + (strcmp(kname, XATTR_NAME_POSIX_ACL_DEFAULT) == 0)) + posix_acl_fix_xattr_from_user(kvalue, size); + } + + error = vfs_setxattr(d, kname, kvalue, size, flags); +out: + if (vvalue) + vfree(vvalue); + else + kfree(kvalue); + return error; +} + +static int path_setxattr(const char __user *pathname, + const char __user *name, const void __user *value, + size_t size, int flags, unsigned int lookup_flags) +{ + struct path path; + int error; +retry: + error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path); + if (error) + return error; + error = mnt_want_write(path.mnt); + if (!error) { + error = setxattr(path.dentry, name, value, size, flags); + mnt_drop_write(path.mnt); + } + path_put(&path); + if (retry_estale(error, lookup_flags)) { + lookup_flags |= LOOKUP_REVAL; + goto retry; + } + return error; +} + +SYSCALL_DEFINE5(setxattr, const char __user *, pathname, + const char __user *, name, const void __user *, value, + size_t, size, int, flags) +{ + return path_setxattr(pathname, name, value, size, flags, LOOKUP_FOLLOW); +} + +SYSCALL_DEFINE5(lsetxattr, const char __user *, pathname, + const char __user *, name, const void __user *, value, + size_t, size, int, flags) +{ + return path_setxattr(pathname, name, value, size, flags, 0); +} + +SYSCALL_DEFINE5(fsetxattr, int, fd, const char __user *, name, + const void __user *,value, size_t, size, int, flags) +{ + struct fd f = fdget(fd); + int error = -EBADF; + + if (!f.file) + return error; + audit_file(f.file); + error = mnt_want_write_file(f.file); + if (!error) { + error = setxattr(f.file->f_path.dentry, name, value, size, flags); + mnt_drop_write_file(f.file); + } + fdput(f); + return error; +} + +/* + * Extended attribute GET operations + */ +static ssize_t +getxattr(struct dentry *d, const char __user *name, void __user *value, + size_t size) +{ + ssize_t error; + void *kvalue = NULL; + void *vvalue = NULL; + char kname[XATTR_NAME_MAX + 1]; + + error = strncpy_from_user(kname, name, sizeof(kname)); + if (error == 0 || error == sizeof(kname)) + error = -ERANGE; + if (error < 0) + return error; + + if (size) { + if (size > XATTR_SIZE_MAX) + size = XATTR_SIZE_MAX; + kvalue = kzalloc(size, GFP_KERNEL | __GFP_NOWARN); + if (!kvalue) { + vvalue = vmalloc(size); + if (!vvalue) + return -ENOMEM; + kvalue = vvalue; + } + } + + error = vfs_getxattr(d, kname, kvalue, size); + if (error > 0) { + if ((strcmp(kname, XATTR_NAME_POSIX_ACL_ACCESS) == 0) || + (strcmp(kname, XATTR_NAME_POSIX_ACL_DEFAULT) == 0)) + posix_acl_fix_xattr_to_user(kvalue, size); + if (size && copy_to_user(value, kvalue, error)) + error = -EFAULT; + } else if (error == -ERANGE && size >= XATTR_SIZE_MAX) { + /* The file system tried to returned a value bigger + than XATTR_SIZE_MAX bytes. Not possible. */ + error = -E2BIG; + } + if (vvalue) + vfree(vvalue); + else + kfree(kvalue); + return error; +} + +static ssize_t path_getxattr(const char __user *pathname, + const char __user *name, void __user *value, + size_t size, unsigned int lookup_flags) +{ + struct path path; + ssize_t error; +retry: + error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path); + if (error) + return error; + error = getxattr(path.dentry, name, value, size); + path_put(&path); + if (retry_estale(error, lookup_flags)) { + lookup_flags |= LOOKUP_REVAL; + goto retry; + } + return error; +} + +SYSCALL_DEFINE4(getxattr, const char __user *, pathname, + const char __user *, name, void __user *, value, size_t, size) +{ + return path_getxattr(pathname, name, value, size, LOOKUP_FOLLOW); +} + +SYSCALL_DEFINE4(lgetxattr, const char __user *, pathname, + const char __user *, name, void __user *, value, size_t, size) +{ + return path_getxattr(pathname, name, value, size, 0); +} + +SYSCALL_DEFINE4(fgetxattr, int, fd, const char __user *, name, + void __user *, value, size_t, size) +{ + struct fd f = fdget(fd); + ssize_t error = -EBADF; + + if (!f.file) + return error; + audit_file(f.file); + error = getxattr(f.file->f_path.dentry, name, value, size); + fdput(f); + return error; +} + +/* + * Extended attribute LIST operations + */ +static ssize_t +listxattr(struct dentry *d, char __user *list, size_t size) +{ + ssize_t error; + char *klist = NULL; + char *vlist = NULL; /* If non-NULL, we used vmalloc() */ + + if (size) { + if (size > XATTR_LIST_MAX) + size = XATTR_LIST_MAX; + klist = kmalloc(size, __GFP_NOWARN | GFP_KERNEL); + if (!klist) { + vlist = vmalloc(size); + if (!vlist) + return -ENOMEM; + klist = vlist; + } + } + + error = vfs_listxattr(d, klist, size); + if (error > 0) { + if (size && copy_to_user(list, klist, error)) + error = -EFAULT; + } else if (error == -ERANGE && size >= XATTR_LIST_MAX) { + /* The file system tried to returned a list bigger + than XATTR_LIST_MAX bytes. Not possible. */ + error = -E2BIG; + } + if (vlist) + vfree(vlist); + else + kfree(klist); + return error; +} + +static ssize_t path_listxattr(const char __user *pathname, char __user *list, + size_t size, unsigned int lookup_flags) +{ + struct path path; + ssize_t error; +retry: + error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path); + if (error) + return error; + error = listxattr(path.dentry, list, size); + path_put(&path); + if (retry_estale(error, lookup_flags)) { + lookup_flags |= LOOKUP_REVAL; + goto retry; + } + return error; +} + +SYSCALL_DEFINE3(listxattr, const char __user *, pathname, char __user *, list, + size_t, size) +{ + return path_listxattr(pathname, list, size, LOOKUP_FOLLOW); +} + +SYSCALL_DEFINE3(llistxattr, const char __user *, pathname, char __user *, list, + size_t, size) +{ + return path_listxattr(pathname, list, size, 0); +} + +SYSCALL_DEFINE3(flistxattr, int, fd, char __user *, list, size_t, size) +{ + struct fd f = fdget(fd); + ssize_t error = -EBADF; + + if (!f.file) + return error; + audit_file(f.file); + error = listxattr(f.file->f_path.dentry, list, size); + fdput(f); + return error; +} + +/* + * Extended attribute REMOVE operations + */ +static long +removexattr(struct dentry *d, const char __user *name) +{ + int error; + char kname[XATTR_NAME_MAX + 1]; + + error = strncpy_from_user(kname, name, sizeof(kname)); + if (error == 0 || error == sizeof(kname)) + error = -ERANGE; + if (error < 0) + return error; + + return vfs_removexattr(d, kname); +} + +static int path_removexattr(const char __user *pathname, + const char __user *name, unsigned int lookup_flags) +{ + struct path path; + int error; +retry: + error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path); + if (error) + return error; + error = mnt_want_write(path.mnt); + if (!error) { + error = removexattr(path.dentry, name); + mnt_drop_write(path.mnt); + } + path_put(&path); + if (retry_estale(error, lookup_flags)) { + lookup_flags |= LOOKUP_REVAL; + goto retry; + } + return error; +} + +SYSCALL_DEFINE2(removexattr, const char __user *, pathname, + const char __user *, name) +{ + return path_removexattr(pathname, name, LOOKUP_FOLLOW); +} + +SYSCALL_DEFINE2(lremovexattr, const char __user *, pathname, + const char __user *, name) +{ + return path_removexattr(pathname, name, 0); +} + +SYSCALL_DEFINE2(fremovexattr, int, fd, const char __user *, name) +{ + struct fd f = fdget(fd); + int error = -EBADF; + + if (!f.file) + return error; + audit_file(f.file); + error = mnt_want_write_file(f.file); + if (!error) { + error = removexattr(f.file->f_path.dentry, name); + mnt_drop_write_file(f.file); + } + fdput(f); + return error; +} + + +static const char * +strcmp_prefix(const char *a, const char *a_prefix) +{ + while (*a_prefix && *a == *a_prefix) { + a++; + a_prefix++; + } + return *a_prefix ? NULL : a; +} + +/* + * In order to implement different sets of xattr operations for each xattr + * prefix with the generic xattr API, a filesystem should create a + * null-terminated array of struct xattr_handler (one for each prefix) and + * hang a pointer to it off of the s_xattr field of the superblock. + * + * The generic_fooxattr() functions will use this list to dispatch xattr + * operations to the correct xattr_handler. + */ +#define for_each_xattr_handler(handlers, handler) \ + for ((handler) = *(handlers)++; \ + (handler) != NULL; \ + (handler) = *(handlers)++) + +/* + * Find the xattr_handler with the matching prefix. + */ +static const struct xattr_handler * +xattr_resolve_name(const struct xattr_handler **handlers, const char **name) +{ + const struct xattr_handler *handler; + + if (!*name) + return NULL; + + for_each_xattr_handler(handlers, handler) { + const char *n = strcmp_prefix(*name, handler->prefix); + if (n) { + *name = n; + break; + } + } + return handler; +} + +/* + * Find the handler for the prefix and dispatch its get() operation. + */ +ssize_t +generic_getxattr(struct dentry *dentry, const char *name, void *buffer, size_t size) +{ + const struct xattr_handler *handler; + + handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name); + if (!handler) + return -EOPNOTSUPP; + return handler->get(dentry, name, buffer, size, handler->flags); +} + +/* + * Combine the results of the list() operation from every xattr_handler in the + * list. + */ +ssize_t +generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size) +{ + const struct xattr_handler *handler, **handlers = dentry->d_sb->s_xattr; + unsigned int size = 0; + + if (!buffer) { + for_each_xattr_handler(handlers, handler) { + size += handler->list(dentry, NULL, 0, NULL, 0, + handler->flags); + } + } else { + char *buf = buffer; + + for_each_xattr_handler(handlers, handler) { + size = handler->list(dentry, buf, buffer_size, + NULL, 0, handler->flags); + if (size > buffer_size) + return -ERANGE; + buf += size; + buffer_size -= size; + } + size = buf - buffer; + } + return size; +} + +/* + * Find the handler for the prefix and dispatch its set() operation. + */ +int +generic_setxattr(struct dentry *dentry, const char *name, const void *value, size_t size, int flags) +{ + const struct xattr_handler *handler; + + if (size == 0) + value = ""; /* empty EA, do not remove */ + handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name); + if (!handler) + return -EOPNOTSUPP; + return handler->set(dentry, name, value, size, flags, handler->flags); +} + +/* + * Find the handler for the prefix and dispatch its set() operation to remove + * any associated extended attribute. + */ +int +generic_removexattr(struct dentry *dentry, const char *name) +{ + const struct xattr_handler *handler; + + handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name); + if (!handler) + return -EOPNOTSUPP; + return handler->set(dentry, name, NULL, 0, + XATTR_REPLACE, handler->flags); +} + +EXPORT_SYMBOL(generic_getxattr); +EXPORT_SYMBOL(generic_listxattr); +EXPORT_SYMBOL(generic_setxattr); +EXPORT_SYMBOL(generic_removexattr); + +/* + * Allocate new xattr and copy in the value; but leave the name to callers. + */ +struct simple_xattr *simple_xattr_alloc(const void *value, size_t size) +{ + struct simple_xattr *new_xattr; + size_t len; + + /* wrap around? */ + len = sizeof(*new_xattr) + size; + if (len < sizeof(*new_xattr)) + return NULL; + + new_xattr = kmalloc(len, GFP_KERNEL); + if (!new_xattr) + return NULL; + + new_xattr->size = size; + memcpy(new_xattr->value, value, size); + return new_xattr; +} + +/* + * xattr GET operation for in-memory/pseudo filesystems + */ +int simple_xattr_get(struct simple_xattrs *xattrs, const char *name, + void *buffer, size_t size) +{ + struct simple_xattr *xattr; + int ret = -ENODATA; + + spin_lock(&xattrs->lock); + list_for_each_entry(xattr, &xattrs->head, list) { + if (strcmp(name, xattr->name)) + continue; + + ret = xattr->size; + if (buffer) { + if (size < xattr->size) + ret = -ERANGE; + else + memcpy(buffer, xattr->value, xattr->size); + } + break; + } + spin_unlock(&xattrs->lock); + return ret; +} + +static int __simple_xattr_set(struct simple_xattrs *xattrs, const char *name, + const void *value, size_t size, int flags) +{ + struct simple_xattr *xattr; + struct simple_xattr *new_xattr = NULL; + int err = 0; + + /* value == NULL means remove */ + if (value) { + new_xattr = simple_xattr_alloc(value, size); + if (!new_xattr) + return -ENOMEM; + + new_xattr->name = kstrdup(name, GFP_KERNEL); + if (!new_xattr->name) { + kfree(new_xattr); + return -ENOMEM; + } + } + + spin_lock(&xattrs->lock); + list_for_each_entry(xattr, &xattrs->head, list) { + if (!strcmp(name, xattr->name)) { + if (flags & XATTR_CREATE) { + xattr = new_xattr; + err = -EEXIST; + } else if (new_xattr) { + list_replace(&xattr->list, &new_xattr->list); + } else { + list_del(&xattr->list); + } + goto out; + } + } + if (flags & XATTR_REPLACE) { + xattr = new_xattr; + err = -ENODATA; + } else { + list_add(&new_xattr->list, &xattrs->head); + xattr = NULL; + } +out: + spin_unlock(&xattrs->lock); + if (xattr) { + kfree(xattr->name); + kfree(xattr); + } + return err; + +} + +/** + * simple_xattr_set - xattr SET operation for in-memory/pseudo filesystems + * @xattrs: target simple_xattr list + * @name: name of the new extended attribute + * @value: value of the new xattr. If %NULL, will remove the attribute + * @size: size of the new xattr + * @flags: %XATTR_{CREATE|REPLACE} + * + * %XATTR_CREATE is set, the xattr shouldn't exist already; otherwise fails + * with -EEXIST. If %XATTR_REPLACE is set, the xattr should exist; + * otherwise, fails with -ENODATA. + * + * Returns 0 on success, -errno on failure. + */ +int simple_xattr_set(struct simple_xattrs *xattrs, const char *name, + const void *value, size_t size, int flags) +{ + if (size == 0) + value = ""; /* empty EA, do not remove */ + return __simple_xattr_set(xattrs, name, value, size, flags); +} + +/* + * xattr REMOVE operation for in-memory/pseudo filesystems + */ +int simple_xattr_remove(struct simple_xattrs *xattrs, const char *name) +{ + return __simple_xattr_set(xattrs, name, NULL, 0, XATTR_REPLACE); +} + +static bool xattr_is_trusted(const char *name) +{ + return !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN); +} + +/* + * xattr LIST operation for in-memory/pseudo filesystems + */ +ssize_t simple_xattr_list(struct simple_xattrs *xattrs, char *buffer, + size_t size) +{ + bool trusted = capable(CAP_SYS_ADMIN); + struct simple_xattr *xattr; + size_t used = 0; + + spin_lock(&xattrs->lock); + list_for_each_entry(xattr, &xattrs->head, list) { + size_t len; + + /* skip "trusted." attributes for unprivileged callers */ + if (!trusted && xattr_is_trusted(xattr->name)) + continue; + + len = strlen(xattr->name) + 1; + used += len; + if (buffer) { + if (size < used) { + used = -ERANGE; + break; + } + memcpy(buffer, xattr->name, len); + buffer += len; + } + } + spin_unlock(&xattrs->lock); + + return used; +} + +/* + * Adds an extended attribute to the list + */ +void simple_xattr_list_add(struct simple_xattrs *xattrs, + struct simple_xattr *new_xattr) +{ + spin_lock(&xattrs->lock); + list_add(&new_xattr->list, &xattrs->head); + spin_unlock(&xattrs->lock); +} |