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1130 lines
27 KiB
1130 lines
27 KiB
// SPDX-License-Identifier: GPL-2.0-only |
|
/* |
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File: fs/xattr.c |
|
|
|
Extended attribute handling. |
|
|
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Copyright (C) 2001 by Andreas Gruenbacher <[email protected]> |
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Copyright (C) 2001 SGI - Silicon Graphics, Inc <[email protected]> |
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Copyright (c) 2004 Red Hat, Inc., James Morris <[email protected]> |
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*/ |
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#include <linux/fs.h> |
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#include <linux/slab.h> |
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#include <linux/file.h> |
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#include <linux/xattr.h> |
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#include <linux/mount.h> |
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#include <linux/namei.h> |
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#include <linux/security.h> |
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#include <linux/evm.h> |
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#include <linux/syscalls.h> |
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#include <linux/export.h> |
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#include <linux/fsnotify.h> |
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#include <linux/audit.h> |
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#include <linux/vmalloc.h> |
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#include <linux/posix_acl_xattr.h> |
|
|
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#include <linux/uaccess.h> |
|
|
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static const char * |
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strcmp_prefix(const char *a, const char *a_prefix) |
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{ |
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while (*a_prefix && *a == *a_prefix) { |
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a++; |
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a_prefix++; |
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} |
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return *a_prefix ? NULL : a; |
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} |
|
|
|
/* |
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* In order to implement different sets of xattr operations for each xattr |
|
* prefix, a filesystem should create a null-terminated array of struct |
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* xattr_handler (one for each prefix) and hang a pointer to it off of the |
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* s_xattr field of the superblock. |
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*/ |
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#define for_each_xattr_handler(handlers, handler) \ |
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if (handlers) \ |
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for ((handler) = *(handlers)++; \ |
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(handler) != NULL; \ |
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(handler) = *(handlers)++) |
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|
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/* |
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* Find the xattr_handler with the matching prefix. |
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*/ |
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static const struct xattr_handler * |
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xattr_resolve_name(struct inode *inode, const char **name) |
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{ |
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const struct xattr_handler **handlers = inode->i_sb->s_xattr; |
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const struct xattr_handler *handler; |
|
|
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if (!(inode->i_opflags & IOP_XATTR)) { |
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if (unlikely(is_bad_inode(inode))) |
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return ERR_PTR(-EIO); |
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return ERR_PTR(-EOPNOTSUPP); |
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} |
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for_each_xattr_handler(handlers, handler) { |
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const char *n; |
|
|
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n = strcmp_prefix(*name, xattr_prefix(handler)); |
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if (n) { |
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if (!handler->prefix ^ !*n) { |
|
if (*n) |
|
continue; |
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return ERR_PTR(-EINVAL); |
|
} |
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*name = n; |
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return handler; |
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} |
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} |
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return ERR_PTR(-EOPNOTSUPP); |
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} |
|
|
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/* |
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* Check permissions for extended attribute access. This is a bit complicated |
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* because different namespaces have very different rules. |
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*/ |
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static int |
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xattr_permission(struct user_namespace *mnt_userns, struct inode *inode, |
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const char *name, int mask) |
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{ |
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/* |
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* We can never set or remove an extended attribute on a read-only |
|
* filesystem or on an immutable / append-only inode. |
|
*/ |
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if (mask & MAY_WRITE) { |
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if (IS_IMMUTABLE(inode) || IS_APPEND(inode)) |
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return -EPERM; |
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/* |
|
* Updating an xattr will likely cause i_uid and i_gid |
|
* to be writen back improperly if their true value is |
|
* unknown to the vfs. |
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*/ |
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if (HAS_UNMAPPED_ID(mnt_userns, inode)) |
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return -EPERM; |
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} |
|
|
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/* |
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* No restriction for security.* and system.* from the VFS. Decision |
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* on these is left to the underlying filesystem / security module. |
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*/ |
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if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN) || |
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!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) |
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return 0; |
|
|
|
/* |
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* The trusted.* namespace can only be accessed by privileged users. |
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*/ |
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if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN)) { |
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if (!capable(CAP_SYS_ADMIN)) |
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return (mask & MAY_WRITE) ? -EPERM : -ENODATA; |
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return 0; |
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} |
|
|
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/* |
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* In the user.* namespace, only regular files and directories can have |
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* extended attributes. For sticky directories, only the owner and |
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* privileged users can write attributes. |
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*/ |
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if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN)) { |
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if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode)) |
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return (mask & MAY_WRITE) ? -EPERM : -ENODATA; |
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if (S_ISDIR(inode->i_mode) && (inode->i_mode & S_ISVTX) && |
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(mask & MAY_WRITE) && |
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!inode_owner_or_capable(mnt_userns, inode)) |
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return -EPERM; |
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} |
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|
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return inode_permission(mnt_userns, inode, mask); |
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} |
|
|
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/* |
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* Look for any handler that deals with the specified namespace. |
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*/ |
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int |
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xattr_supported_namespace(struct inode *inode, const char *prefix) |
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{ |
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const struct xattr_handler **handlers = inode->i_sb->s_xattr; |
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const struct xattr_handler *handler; |
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size_t preflen; |
|
|
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if (!(inode->i_opflags & IOP_XATTR)) { |
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if (unlikely(is_bad_inode(inode))) |
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return -EIO; |
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return -EOPNOTSUPP; |
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} |
|
|
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preflen = strlen(prefix); |
|
|
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for_each_xattr_handler(handlers, handler) { |
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if (!strncmp(xattr_prefix(handler), prefix, preflen)) |
|
return 0; |
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} |
|
|
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return -EOPNOTSUPP; |
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} |
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EXPORT_SYMBOL(xattr_supported_namespace); |
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|
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int |
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__vfs_setxattr(struct user_namespace *mnt_userns, struct dentry *dentry, |
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struct inode *inode, const char *name, const void *value, |
|
size_t size, int flags) |
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{ |
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const struct xattr_handler *handler; |
|
|
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handler = xattr_resolve_name(inode, &name); |
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if (IS_ERR(handler)) |
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return PTR_ERR(handler); |
|
if (!handler->set) |
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return -EOPNOTSUPP; |
|
if (size == 0) |
|
value = ""; /* empty EA, do not remove */ |
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return handler->set(handler, mnt_userns, dentry, inode, name, value, |
|
size, flags); |
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} |
|
EXPORT_SYMBOL(__vfs_setxattr); |
|
|
|
/** |
|
* __vfs_setxattr_noperm - perform setxattr operation without performing |
|
* permission checks. |
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* |
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* @mnt_userns - user namespace of the mount the inode was found from |
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* @dentry - object to perform setxattr on |
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* @name - xattr name to set |
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* @value - value to set @name to |
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* @size - size of @value |
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* @flags - flags to pass into filesystem operations |
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* |
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* returns the result of the internal setxattr or setsecurity operations. |
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* |
|
* 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. |
|
*/ |
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int __vfs_setxattr_noperm(struct user_namespace *mnt_userns, |
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struct dentry *dentry, const char *name, |
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const void *value, size_t size, int flags) |
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{ |
|
struct inode *inode = dentry->d_inode; |
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int error = -EAGAIN; |
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int issec = !strncmp(name, XATTR_SECURITY_PREFIX, |
|
XATTR_SECURITY_PREFIX_LEN); |
|
|
|
if (issec) |
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inode->i_flags &= ~S_NOSEC; |
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if (inode->i_opflags & IOP_XATTR) { |
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error = __vfs_setxattr(mnt_userns, dentry, inode, name, value, |
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size, flags); |
|
if (!error) { |
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fsnotify_xattr(dentry); |
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security_inode_post_setxattr(dentry, name, value, |
|
size, flags); |
|
} |
|
} else { |
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if (unlikely(is_bad_inode(inode))) |
|
return -EIO; |
|
} |
|
if (error == -EAGAIN) { |
|
error = -EOPNOTSUPP; |
|
|
|
if (issec) { |
|
const char *suffix = name + XATTR_SECURITY_PREFIX_LEN; |
|
|
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error = security_inode_setsecurity(inode, suffix, value, |
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size, flags); |
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if (!error) |
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fsnotify_xattr(dentry); |
|
} |
|
} |
|
|
|
return error; |
|
} |
|
|
|
/** |
|
* __vfs_setxattr_locked - set an extended attribute while holding the inode |
|
* lock |
|
* |
|
* @dentry: object to perform setxattr on |
|
* @name: xattr name to set |
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* @value: value to set @name to |
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* @size: size of @value |
|
* @flags: flags to pass into filesystem operations |
|
* @delegated_inode: on return, will contain an inode pointer that |
|
* a delegation was broken on, NULL if none. |
|
*/ |
|
int |
|
__vfs_setxattr_locked(struct user_namespace *mnt_userns, struct dentry *dentry, |
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const char *name, const void *value, size_t size, |
|
int flags, struct inode **delegated_inode) |
|
{ |
|
struct inode *inode = dentry->d_inode; |
|
int error; |
|
|
|
error = xattr_permission(mnt_userns, inode, name, MAY_WRITE); |
|
if (error) |
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return error; |
|
|
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error = security_inode_setxattr(mnt_userns, dentry, name, value, size, |
|
flags); |
|
if (error) |
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goto out; |
|
|
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error = try_break_deleg(inode, delegated_inode); |
|
if (error) |
|
goto out; |
|
|
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error = __vfs_setxattr_noperm(mnt_userns, dentry, name, value, |
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size, flags); |
|
|
|
out: |
|
return error; |
|
} |
|
EXPORT_SYMBOL_GPL(__vfs_setxattr_locked); |
|
|
|
int |
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vfs_setxattr(struct user_namespace *mnt_userns, struct dentry *dentry, |
|
const char *name, const void *value, size_t size, int flags) |
|
{ |
|
struct inode *inode = dentry->d_inode; |
|
struct inode *delegated_inode = NULL; |
|
const void *orig_value = value; |
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int error; |
|
|
|
if (size && strcmp(name, XATTR_NAME_CAPS) == 0) { |
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error = cap_convert_nscap(mnt_userns, dentry, &value, size); |
|
if (error < 0) |
|
return error; |
|
size = error; |
|
} |
|
|
|
retry_deleg: |
|
inode_lock(inode); |
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error = __vfs_setxattr_locked(mnt_userns, dentry, name, value, size, |
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flags, &delegated_inode); |
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inode_unlock(inode); |
|
|
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if (delegated_inode) { |
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error = break_deleg_wait(&delegated_inode); |
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if (!error) |
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goto retry_deleg; |
|
} |
|
if (value != orig_value) |
|
kfree(value); |
|
|
|
return error; |
|
} |
|
EXPORT_SYMBOL_GPL(vfs_setxattr); |
|
|
|
static ssize_t |
|
xattr_getsecurity(struct user_namespace *mnt_userns, struct inode *inode, |
|
const char *name, void *value, size_t size) |
|
{ |
|
void *buffer = NULL; |
|
ssize_t len; |
|
|
|
if (!value || !size) { |
|
len = security_inode_getsecurity(mnt_userns, inode, name, |
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&buffer, false); |
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goto out_noalloc; |
|
} |
|
|
|
len = security_inode_getsecurity(mnt_userns, inode, name, &buffer, |
|
true); |
|
if (len < 0) |
|
return len; |
|
if (size < len) { |
|
len = -ERANGE; |
|
goto out; |
|
} |
|
memcpy(value, buffer, len); |
|
out: |
|
kfree(buffer); |
|
out_noalloc: |
|
return len; |
|
} |
|
|
|
/* |
|
* vfs_getxattr_alloc - allocate memory, if necessary, before calling getxattr |
|
* |
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* 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 user_namespace *mnt_userns, struct dentry *dentry, |
|
const char *name, char **xattr_value, size_t xattr_size, |
|
gfp_t flags) |
|
{ |
|
const struct xattr_handler *handler; |
|
struct inode *inode = dentry->d_inode; |
|
char *value = *xattr_value; |
|
int error; |
|
|
|
error = xattr_permission(mnt_userns, inode, name, MAY_READ); |
|
if (error) |
|
return error; |
|
|
|
handler = xattr_resolve_name(inode, &name); |
|
if (IS_ERR(handler)) |
|
return PTR_ERR(handler); |
|
if (!handler->get) |
|
return -EOPNOTSUPP; |
|
error = handler->get(handler, dentry, inode, 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 = handler->get(handler, dentry, inode, name, value, error); |
|
*xattr_value = value; |
|
return error; |
|
} |
|
|
|
ssize_t |
|
__vfs_getxattr(struct dentry *dentry, struct inode *inode, const char *name, |
|
void *value, size_t size) |
|
{ |
|
const struct xattr_handler *handler; |
|
|
|
handler = xattr_resolve_name(inode, &name); |
|
if (IS_ERR(handler)) |
|
return PTR_ERR(handler); |
|
if (!handler->get) |
|
return -EOPNOTSUPP; |
|
return handler->get(handler, dentry, inode, name, value, size); |
|
} |
|
EXPORT_SYMBOL(__vfs_getxattr); |
|
|
|
ssize_t |
|
vfs_getxattr(struct user_namespace *mnt_userns, struct dentry *dentry, |
|
const char *name, void *value, size_t size) |
|
{ |
|
struct inode *inode = dentry->d_inode; |
|
int error; |
|
|
|
error = xattr_permission(mnt_userns, 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(mnt_userns, inode, suffix, value, |
|
size); |
|
/* |
|
* Only overwrite the return value if a security module |
|
* is actually active. |
|
*/ |
|
if (ret == -EOPNOTSUPP) |
|
goto nolsm; |
|
return ret; |
|
} |
|
nolsm: |
|
return __vfs_getxattr(dentry, inode, name, value, size); |
|
} |
|
EXPORT_SYMBOL_GPL(vfs_getxattr); |
|
|
|
ssize_t |
|
vfs_listxattr(struct dentry *dentry, char *list, size_t size) |
|
{ |
|
struct inode *inode = d_inode(dentry); |
|
ssize_t error; |
|
|
|
error = security_inode_listxattr(dentry); |
|
if (error) |
|
return error; |
|
if (inode->i_op->listxattr && (inode->i_opflags & IOP_XATTR)) { |
|
error = inode->i_op->listxattr(dentry, list, size); |
|
} else { |
|
error = security_inode_listsecurity(inode, list, size); |
|
if (size && error > size) |
|
error = -ERANGE; |
|
} |
|
return error; |
|
} |
|
EXPORT_SYMBOL_GPL(vfs_listxattr); |
|
|
|
int |
|
__vfs_removexattr(struct user_namespace *mnt_userns, struct dentry *dentry, |
|
const char *name) |
|
{ |
|
struct inode *inode = d_inode(dentry); |
|
const struct xattr_handler *handler; |
|
|
|
handler = xattr_resolve_name(inode, &name); |
|
if (IS_ERR(handler)) |
|
return PTR_ERR(handler); |
|
if (!handler->set) |
|
return -EOPNOTSUPP; |
|
return handler->set(handler, mnt_userns, dentry, inode, name, NULL, 0, |
|
XATTR_REPLACE); |
|
} |
|
EXPORT_SYMBOL(__vfs_removexattr); |
|
|
|
/** |
|
* __vfs_removexattr_locked - set an extended attribute while holding the inode |
|
* lock |
|
* |
|
* @dentry: object to perform setxattr on |
|
* @name: name of xattr to remove |
|
* @delegated_inode: on return, will contain an inode pointer that |
|
* a delegation was broken on, NULL if none. |
|
*/ |
|
int |
|
__vfs_removexattr_locked(struct user_namespace *mnt_userns, |
|
struct dentry *dentry, const char *name, |
|
struct inode **delegated_inode) |
|
{ |
|
struct inode *inode = dentry->d_inode; |
|
int error; |
|
|
|
error = xattr_permission(mnt_userns, inode, name, MAY_WRITE); |
|
if (error) |
|
return error; |
|
|
|
error = security_inode_removexattr(mnt_userns, dentry, name); |
|
if (error) |
|
goto out; |
|
|
|
error = try_break_deleg(inode, delegated_inode); |
|
if (error) |
|
goto out; |
|
|
|
error = __vfs_removexattr(mnt_userns, dentry, name); |
|
|
|
if (!error) { |
|
fsnotify_xattr(dentry); |
|
evm_inode_post_removexattr(dentry, name); |
|
} |
|
|
|
out: |
|
return error; |
|
} |
|
EXPORT_SYMBOL_GPL(__vfs_removexattr_locked); |
|
|
|
int |
|
vfs_removexattr(struct user_namespace *mnt_userns, struct dentry *dentry, |
|
const char *name) |
|
{ |
|
struct inode *inode = dentry->d_inode; |
|
struct inode *delegated_inode = NULL; |
|
int error; |
|
|
|
retry_deleg: |
|
inode_lock(inode); |
|
error = __vfs_removexattr_locked(mnt_userns, dentry, |
|
name, &delegated_inode); |
|
inode_unlock(inode); |
|
|
|
if (delegated_inode) { |
|
error = break_deleg_wait(&delegated_inode); |
|
if (!error) |
|
goto retry_deleg; |
|
} |
|
|
|
return error; |
|
} |
|
EXPORT_SYMBOL_GPL(vfs_removexattr); |
|
|
|
/* |
|
* Extended attribute SET operations |
|
*/ |
|
static long |
|
setxattr(struct user_namespace *mnt_userns, struct dentry *d, |
|
const char __user *name, const void __user *value, size_t size, |
|
int flags) |
|
{ |
|
int error; |
|
void *kvalue = NULL; |
|
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 = kvmalloc(size, GFP_KERNEL); |
|
if (!kvalue) |
|
return -ENOMEM; |
|
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(mnt_userns, kvalue, size); |
|
} |
|
|
|
error = vfs_setxattr(mnt_userns, d, kname, kvalue, size, flags); |
|
out: |
|
kvfree(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(mnt_user_ns(path.mnt), 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(file_mnt_user_ns(f.file), |
|
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 user_namespace *mnt_userns, struct dentry *d, |
|
const char __user *name, void __user *value, size_t size) |
|
{ |
|
ssize_t error; |
|
void *kvalue = 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 = kvzalloc(size, GFP_KERNEL); |
|
if (!kvalue) |
|
return -ENOMEM; |
|
} |
|
|
|
error = vfs_getxattr(mnt_userns, 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(mnt_userns, kvalue, error); |
|
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; |
|
} |
|
|
|
kvfree(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(mnt_user_ns(path.mnt), 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(file_mnt_user_ns(f.file), 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; |
|
|
|
if (size) { |
|
if (size > XATTR_LIST_MAX) |
|
size = XATTR_LIST_MAX; |
|
klist = kvmalloc(size, GFP_KERNEL); |
|
if (!klist) |
|
return -ENOMEM; |
|
} |
|
|
|
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; |
|
} |
|
|
|
kvfree(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 user_namespace *mnt_userns, 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(mnt_userns, 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(mnt_user_ns(path.mnt), 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(file_mnt_user_ns(f.file), |
|
f.file->f_path.dentry, name); |
|
mnt_drop_write_file(f.file); |
|
} |
|
fdput(f); |
|
return error; |
|
} |
|
|
|
/* |
|
* 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) { |
|
if (!handler->name || |
|
(handler->list && !handler->list(dentry))) |
|
continue; |
|
size += strlen(handler->name) + 1; |
|
} |
|
} else { |
|
char *buf = buffer; |
|
size_t len; |
|
|
|
for_each_xattr_handler(handlers, handler) { |
|
if (!handler->name || |
|
(handler->list && !handler->list(dentry))) |
|
continue; |
|
len = strlen(handler->name); |
|
if (len + 1 > buffer_size) |
|
return -ERANGE; |
|
memcpy(buf, handler->name, len + 1); |
|
buf += len + 1; |
|
buffer_size -= len + 1; |
|
} |
|
size = buf - buffer; |
|
} |
|
return size; |
|
} |
|
EXPORT_SYMBOL(generic_listxattr); |
|
|
|
/** |
|
* xattr_full_name - Compute full attribute name from suffix |
|
* |
|
* @handler: handler of the xattr_handler operation |
|
* @name: name passed to the xattr_handler operation |
|
* |
|
* The get and set xattr handler operations are called with the remainder of |
|
* the attribute name after skipping the handler's prefix: for example, "foo" |
|
* is passed to the get operation of a handler with prefix "user." to get |
|
* attribute "user.foo". The full name is still "there" in the name though. |
|
* |
|
* Note: the list xattr handler operation when called from the vfs is passed a |
|
* NULL name; some file systems use this operation internally, with varying |
|
* semantics. |
|
*/ |
|
const char *xattr_full_name(const struct xattr_handler *handler, |
|
const char *name) |
|
{ |
|
size_t prefix_len = strlen(xattr_prefix(handler)); |
|
|
|
return name - prefix_len; |
|
} |
|
EXPORT_SYMBOL(xattr_full_name); |
|
|
|
/* |
|
* 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 = kvmalloc(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; |
|
} |
|
|
|
/** |
|
* simple_xattr_set - xattr SET operation for in-memory/pseudo filesystems |
|
* @xattrs: target simple_xattr list |
|
* @name: name of the extended attribute |
|
* @value: value of the xattr. If %NULL, will remove the attribute. |
|
* @size: size of the new xattr |
|
* @flags: %XATTR_{CREATE|REPLACE} |
|
* @removed_size: returns size of the removed xattr, -1 if none removed |
|
* |
|
* %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, |
|
ssize_t *removed_size) |
|
{ |
|
struct simple_xattr *xattr; |
|
struct simple_xattr *new_xattr = NULL; |
|
int err = 0; |
|
|
|
if (removed_size) |
|
*removed_size = -1; |
|
|
|
/* 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) { |
|
kvfree(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); |
|
if (removed_size) |
|
*removed_size = xattr->size; |
|
} else { |
|
list_del(&xattr->list); |
|
if (removed_size) |
|
*removed_size = xattr->size; |
|
} |
|
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); |
|
kvfree(xattr); |
|
} |
|
return err; |
|
|
|
} |
|
|
|
static bool xattr_is_trusted(const char *name) |
|
{ |
|
return !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN); |
|
} |
|
|
|
static int xattr_list_one(char **buffer, ssize_t *remaining_size, |
|
const char *name) |
|
{ |
|
size_t len = strlen(name) + 1; |
|
if (*buffer) { |
|
if (*remaining_size < len) |
|
return -ERANGE; |
|
memcpy(*buffer, name, len); |
|
*buffer += len; |
|
} |
|
*remaining_size -= len; |
|
return 0; |
|
} |
|
|
|
/* |
|
* xattr LIST operation for in-memory/pseudo filesystems |
|
*/ |
|
ssize_t simple_xattr_list(struct inode *inode, struct simple_xattrs *xattrs, |
|
char *buffer, size_t size) |
|
{ |
|
bool trusted = capable(CAP_SYS_ADMIN); |
|
struct simple_xattr *xattr; |
|
ssize_t remaining_size = size; |
|
int err = 0; |
|
|
|
#ifdef CONFIG_FS_POSIX_ACL |
|
if (IS_POSIXACL(inode)) { |
|
if (inode->i_acl) { |
|
err = xattr_list_one(&buffer, &remaining_size, |
|
XATTR_NAME_POSIX_ACL_ACCESS); |
|
if (err) |
|
return err; |
|
} |
|
if (inode->i_default_acl) { |
|
err = xattr_list_one(&buffer, &remaining_size, |
|
XATTR_NAME_POSIX_ACL_DEFAULT); |
|
if (err) |
|
return err; |
|
} |
|
} |
|
#endif |
|
|
|
spin_lock(&xattrs->lock); |
|
list_for_each_entry(xattr, &xattrs->head, list) { |
|
/* skip "trusted." attributes for unprivileged callers */ |
|
if (!trusted && xattr_is_trusted(xattr->name)) |
|
continue; |
|
|
|
err = xattr_list_one(&buffer, &remaining_size, xattr->name); |
|
if (err) |
|
break; |
|
} |
|
spin_unlock(&xattrs->lock); |
|
|
|
return err ? err : size - remaining_size; |
|
} |
|
|
|
/* |
|
* 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); |
|
}
|
|
|