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![Tycho Andersen](/assets/img/avatar_default.png)
When interacting with extended attributes the vfs verifies that the caller is privileged over the inode with which the extended attribute is associated. For posix access and posix default extended attributes a uid or gid can be stored on-disk. Let the functions handle posix extended attributes on idmapped mounts. If the inode is accessed through an idmapped mount we need to map it according to the mount's user namespace. Afterwards the checks are identical to non-idmapped mounts. This has no effect for e.g. security xattrs since they don't store uids or gids and don't perform permission checks on them like posix acls do. Link: https://lore.kernel.org/r/20210121131959.646623-10-christian.brauner@ubuntu.com Cc: Christoph Hellwig <hch@lst.de> Cc: David Howells <dhowells@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: linux-fsdevel@vger.kernel.org Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: James Morris <jamorris@linux.microsoft.com> Signed-off-by: Tycho Andersen <tycho@tycho.pizza> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
127 lines
3.9 KiB
C
127 lines
3.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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File: linux/xattr.h
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Extended attributes handling.
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Copyright (C) 2001 by Andreas Gruenbacher <a.gruenbacher@computer.org>
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Copyright (c) 2001-2002 Silicon Graphics, Inc. All Rights Reserved.
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Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
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*/
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#ifndef _LINUX_XATTR_H
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#define _LINUX_XATTR_H
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#include <linux/slab.h>
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#include <linux/types.h>
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#include <linux/spinlock.h>
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#include <linux/mm.h>
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#include <linux/user_namespace.h>
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#include <uapi/linux/xattr.h>
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struct inode;
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struct dentry;
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/*
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* struct xattr_handler: When @name is set, match attributes with exactly that
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* name. When @prefix is set instead, match attributes with that prefix and
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* with a non-empty suffix.
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*/
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struct xattr_handler {
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const char *name;
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const char *prefix;
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int flags; /* fs private flags */
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bool (*list)(struct dentry *dentry);
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int (*get)(const struct xattr_handler *, struct dentry *dentry,
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struct inode *inode, const char *name, void *buffer,
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size_t size);
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int (*set)(const struct xattr_handler *,
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struct user_namespace *mnt_userns, struct dentry *dentry,
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struct inode *inode, const char *name, const void *buffer,
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size_t size, int flags);
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};
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const char *xattr_full_name(const struct xattr_handler *, const char *);
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struct xattr {
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const char *name;
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void *value;
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size_t value_len;
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};
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ssize_t __vfs_getxattr(struct dentry *, struct inode *, const char *, void *, size_t);
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ssize_t vfs_getxattr(struct user_namespace *, struct dentry *, const char *,
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void *, size_t);
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ssize_t vfs_listxattr(struct dentry *d, char *list, size_t size);
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int __vfs_setxattr(struct user_namespace *, struct dentry *, struct inode *,
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const char *, const void *, size_t, int);
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int __vfs_setxattr_noperm(struct user_namespace *, struct dentry *,
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const char *, const void *, size_t, int);
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int __vfs_setxattr_locked(struct user_namespace *, struct dentry *,
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const char *, const void *, size_t, int,
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struct inode **);
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int vfs_setxattr(struct user_namespace *, struct dentry *, const char *,
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const void *, size_t, int);
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int __vfs_removexattr(struct user_namespace *, struct dentry *, const char *);
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int __vfs_removexattr_locked(struct user_namespace *, struct dentry *,
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const char *, struct inode **);
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int vfs_removexattr(struct user_namespace *, struct dentry *, const char *);
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ssize_t generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size);
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ssize_t vfs_getxattr_alloc(struct user_namespace *mnt_userns,
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struct dentry *dentry, const char *name,
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char **xattr_value, size_t size, gfp_t flags);
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int xattr_supported_namespace(struct inode *inode, const char *prefix);
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static inline const char *xattr_prefix(const struct xattr_handler *handler)
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{
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return handler->prefix ?: handler->name;
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}
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struct simple_xattrs {
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struct list_head head;
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spinlock_t lock;
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};
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struct simple_xattr {
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struct list_head list;
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char *name;
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size_t size;
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char value[];
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};
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/*
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* initialize the simple_xattrs structure
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*/
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static inline void simple_xattrs_init(struct simple_xattrs *xattrs)
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{
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INIT_LIST_HEAD(&xattrs->head);
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spin_lock_init(&xattrs->lock);
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}
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/*
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* free all the xattrs
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*/
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static inline void simple_xattrs_free(struct simple_xattrs *xattrs)
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{
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struct simple_xattr *xattr, *node;
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list_for_each_entry_safe(xattr, node, &xattrs->head, list) {
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kfree(xattr->name);
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kvfree(xattr);
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}
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}
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struct simple_xattr *simple_xattr_alloc(const void *value, size_t size);
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int simple_xattr_get(struct simple_xattrs *xattrs, const char *name,
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void *buffer, size_t size);
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int simple_xattr_set(struct simple_xattrs *xattrs, const char *name,
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const void *value, size_t size, int flags,
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ssize_t *removed_size);
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ssize_t simple_xattr_list(struct inode *inode, struct simple_xattrs *xattrs, char *buffer,
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size_t size);
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void simple_xattr_list_add(struct simple_xattrs *xattrs,
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struct simple_xattr *new_xattr);
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#endif /* _LINUX_XATTR_H */
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