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3a7bb21b6f
Commitf2620f166e
caused the kernel to start emitting POSIX ACL xattrs for NFSv4 inodes, which it doesn't support. The only other user of generic_listxattr is HFS (classic) and it doesn't support POSIX ACLs either. Fixes:f2620f166e
xattr: simplify listxattr helpers Reported-by: Ondrej Valousek <ondrej.valousek.xm@renesas.com> Signed-off-by: Jeff Layton <jlayton@kernel.org> Message-Id: <20230516124655.82283-1-jlayton@kernel.org> Signed-off-by: Christian Brauner <brauner@kernel.org>
1393 lines
35 KiB
C
1393 lines
35 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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File: fs/xattr.c
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Extended attribute handling.
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Copyright (C) 2001 by Andreas Gruenbacher <a.gruenbacher@computer.org>
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Copyright (C) 2001 SGI - Silicon Graphics, Inc <linux-xfs@oss.sgi.com>
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Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
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*/
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#include <linux/fs.h>
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#include <linux/filelock.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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#include "internal.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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/*
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* In order to implement different sets of xattr operations for each xattr
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* 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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* 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) {
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if (*n)
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continue;
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return ERR_PTR(-EINVAL);
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}
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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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* may_write_xattr - check whether inode allows writing xattr
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* @idmap: idmap of the mount the inode was found from
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* @inode: the inode on which to set an xattr
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*
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* Check whether the inode allows writing xattrs. Specifically, we can never
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* set or remove an extended attribute on a read-only filesystem or on an
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* immutable / append-only inode.
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*
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* We also need to ensure that the inode has a mapping in the mount to
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* not risk writing back invalid i_{g,u}id values.
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*
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* Return: On success zero is returned. On error a negative errno is returned.
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*/
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int may_write_xattr(struct mnt_idmap *idmap, struct inode *inode)
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{
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if (IS_IMMUTABLE(inode))
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return -EPERM;
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if (IS_APPEND(inode))
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return -EPERM;
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if (HAS_UNMAPPED_ID(idmap, inode))
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return -EPERM;
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return 0;
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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 mnt_idmap *idmap, struct inode *inode,
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const char *name, int mask)
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{
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if (mask & MAY_WRITE) {
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int ret;
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ret = may_write_xattr(idmap, inode);
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if (ret)
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return ret;
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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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/*
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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(idmap, inode))
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return -EPERM;
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}
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return inode_permission(idmap, 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_supports_user_prefix(struct inode *inode)
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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 -EIO;
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return -EOPNOTSUPP;
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}
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for_each_xattr_handler(handlers, handler) {
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if (!strncmp(xattr_prefix(handler), XATTR_USER_PREFIX,
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XATTR_USER_PREFIX_LEN))
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return 0;
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}
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return -EOPNOTSUPP;
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}
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EXPORT_SYMBOL(xattr_supports_user_prefix);
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int
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__vfs_setxattr(struct mnt_idmap *idmap, struct dentry *dentry,
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struct inode *inode, const char *name, const void *value,
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size_t size, int flags)
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{
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const struct xattr_handler *handler;
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if (is_posix_acl_xattr(name))
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return -EOPNOTSUPP;
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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);
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if (!handler->set)
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return -EOPNOTSUPP;
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if (size == 0)
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value = ""; /* empty EA, do not remove */
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return handler->set(handler, idmap, dentry, inode, name, value,
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size, flags);
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}
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EXPORT_SYMBOL(__vfs_setxattr);
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/**
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* __vfs_setxattr_noperm - perform setxattr operation without performing
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* permission checks.
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*
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* @idmap: idmap 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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*
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* This function requires the caller to lock the inode's i_mutex before it
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* is executed. It also assumes that the caller will make the appropriate
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* permission checks.
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*/
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int __vfs_setxattr_noperm(struct mnt_idmap *idmap,
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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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{
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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,
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XATTR_SECURITY_PREFIX_LEN);
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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(idmap, dentry, inode, name, value,
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size, flags);
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if (!error) {
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fsnotify_xattr(dentry);
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security_inode_post_setxattr(dentry, name, value,
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size, flags);
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}
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} else {
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if (unlikely(is_bad_inode(inode)))
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return -EIO;
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}
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if (error == -EAGAIN) {
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error = -EOPNOTSUPP;
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if (issec) {
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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);
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}
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}
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return error;
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}
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/**
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* __vfs_setxattr_locked - set an extended attribute while holding the inode
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* lock
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*
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* @idmap: idmap of the mount of the target inode
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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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* @delegated_inode: on return, will contain an inode pointer that
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* a delegation was broken on, NULL if none.
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*/
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int
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__vfs_setxattr_locked(struct mnt_idmap *idmap, struct dentry *dentry,
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const char *name, const void *value, size_t size,
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int flags, struct inode **delegated_inode)
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{
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struct inode *inode = dentry->d_inode;
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int error;
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error = xattr_permission(idmap, inode, name, MAY_WRITE);
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if (error)
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return error;
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error = security_inode_setxattr(idmap, dentry, name, value, size,
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flags);
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if (error)
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goto out;
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error = try_break_deleg(inode, delegated_inode);
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if (error)
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goto out;
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error = __vfs_setxattr_noperm(idmap, dentry, name, value,
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size, flags);
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out:
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return error;
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}
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EXPORT_SYMBOL_GPL(__vfs_setxattr_locked);
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int
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vfs_setxattr(struct mnt_idmap *idmap, struct dentry *dentry,
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const char *name, const void *value, size_t size, int flags)
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{
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struct inode *inode = dentry->d_inode;
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struct inode *delegated_inode = NULL;
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const void *orig_value = value;
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int error;
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if (size && strcmp(name, XATTR_NAME_CAPS) == 0) {
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error = cap_convert_nscap(idmap, dentry, &value, size);
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if (error < 0)
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return error;
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size = error;
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}
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retry_deleg:
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inode_lock(inode);
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error = __vfs_setxattr_locked(idmap, 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;
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}
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if (value != orig_value)
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kfree(value);
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return error;
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}
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EXPORT_SYMBOL_GPL(vfs_setxattr);
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static ssize_t
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xattr_getsecurity(struct mnt_idmap *idmap, struct inode *inode,
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const char *name, void *value, size_t size)
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{
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void *buffer = NULL;
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ssize_t len;
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if (!value || !size) {
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len = security_inode_getsecurity(idmap, inode, name,
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&buffer, false);
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goto out_noalloc;
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}
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len = security_inode_getsecurity(idmap, inode, name, &buffer,
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true);
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if (len < 0)
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return len;
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if (size < len) {
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len = -ERANGE;
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goto out;
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}
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memcpy(value, buffer, len);
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out:
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kfree(buffer);
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out_noalloc:
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return len;
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}
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/*
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* vfs_getxattr_alloc - allocate memory, if necessary, before calling getxattr
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*
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* Allocate memory, if not already allocated, or re-allocate correct size,
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* before retrieving the extended attribute. The xattr value buffer should
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* always be freed by the caller, even on error.
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*
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* Returns the result of alloc, if failed, or the getxattr operation.
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*/
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int
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vfs_getxattr_alloc(struct mnt_idmap *idmap, struct dentry *dentry,
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const char *name, char **xattr_value, size_t xattr_size,
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gfp_t flags)
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{
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const struct xattr_handler *handler;
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struct inode *inode = dentry->d_inode;
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char *value = *xattr_value;
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int error;
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error = xattr_permission(idmap, inode, name, MAY_READ);
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if (error)
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return error;
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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);
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if (!handler->get)
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return -EOPNOTSUPP;
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error = handler->get(handler, dentry, inode, name, NULL, 0);
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if (error < 0)
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return error;
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|
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if (!value || (error > xattr_size)) {
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value = krealloc(*xattr_value, error + 1, flags);
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if (!value)
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return -ENOMEM;
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memset(value, 0, error + 1);
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}
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|
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error = handler->get(handler, dentry, inode, name, value, error);
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*xattr_value = value;
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return error;
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}
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ssize_t
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__vfs_getxattr(struct dentry *dentry, struct inode *inode, const char *name,
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void *value, size_t size)
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{
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const struct xattr_handler *handler;
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|
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if (is_posix_acl_xattr(name))
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return -EOPNOTSUPP;
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|
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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);
|
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if (!handler->get)
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return -EOPNOTSUPP;
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return handler->get(handler, dentry, inode, name, value, size);
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}
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EXPORT_SYMBOL(__vfs_getxattr);
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|
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ssize_t
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vfs_getxattr(struct mnt_idmap *idmap, struct dentry *dentry,
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const char *name, void *value, size_t size)
|
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{
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struct inode *inode = dentry->d_inode;
|
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int error;
|
|
|
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error = xattr_permission(idmap, inode, name, MAY_READ);
|
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if (error)
|
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return error;
|
|
|
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error = security_inode_getxattr(dentry, name);
|
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if (error)
|
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return error;
|
|
|
|
if (!strncmp(name, XATTR_SECURITY_PREFIX,
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XATTR_SECURITY_PREFIX_LEN)) {
|
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const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
|
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int ret = xattr_getsecurity(idmap, inode, suffix, value,
|
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size);
|
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/*
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|
* Only overwrite the return value if a security module
|
|
* is actually active.
|
|
*/
|
|
if (ret == -EOPNOTSUPP)
|
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goto nolsm;
|
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return ret;
|
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}
|
|
nolsm:
|
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return __vfs_getxattr(dentry, inode, name, value, size);
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}
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|
EXPORT_SYMBOL_GPL(vfs_getxattr);
|
|
|
|
/**
|
|
* vfs_listxattr - retrieve \0 separated list of xattr names
|
|
* @dentry: the dentry from whose inode the xattr names are retrieved
|
|
* @list: buffer to store xattr names into
|
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* @size: size of the buffer
|
|
*
|
|
* This function returns the names of all xattrs associated with the
|
|
* inode of @dentry.
|
|
*
|
|
* Note, for legacy reasons the vfs_listxattr() function lists POSIX
|
|
* ACLs as well. Since POSIX ACLs are decoupled from IOP_XATTR the
|
|
* vfs_listxattr() function doesn't check for this flag since a
|
|
* filesystem could implement POSIX ACLs without implementing any other
|
|
* xattrs.
|
|
*
|
|
* However, since all codepaths that remove IOP_XATTR also assign of
|
|
* inode operations that either don't implement or implement a stub
|
|
* ->listxattr() operation.
|
|
*
|
|
* Return: On success, the size of the buffer that was used. On error a
|
|
* negative error code.
|
|
*/
|
|
ssize_t
|
|
vfs_listxattr(struct dentry *dentry, char *list, size_t size)
|
|
{
|
|
struct inode *inode = d_inode(dentry);
|
|
ssize_t error;
|
|
|
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error = security_inode_listxattr(dentry);
|
|
if (error)
|
|
return error;
|
|
|
|
if (inode->i_op->listxattr) {
|
|
error = inode->i_op->listxattr(dentry, list, size);
|
|
} else {
|
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error = security_inode_listsecurity(inode, list, size);
|
|
if (size && error > size)
|
|
error = -ERANGE;
|
|
}
|
|
return error;
|
|
}
|
|
EXPORT_SYMBOL_GPL(vfs_listxattr);
|
|
|
|
int
|
|
__vfs_removexattr(struct mnt_idmap *idmap, struct dentry *dentry,
|
|
const char *name)
|
|
{
|
|
struct inode *inode = d_inode(dentry);
|
|
const struct xattr_handler *handler;
|
|
|
|
if (is_posix_acl_xattr(name))
|
|
return -EOPNOTSUPP;
|
|
|
|
handler = xattr_resolve_name(inode, &name);
|
|
if (IS_ERR(handler))
|
|
return PTR_ERR(handler);
|
|
if (!handler->set)
|
|
return -EOPNOTSUPP;
|
|
return handler->set(handler, idmap, dentry, inode, name, NULL, 0,
|
|
XATTR_REPLACE);
|
|
}
|
|
EXPORT_SYMBOL(__vfs_removexattr);
|
|
|
|
/**
|
|
* __vfs_removexattr_locked - set an extended attribute while holding the inode
|
|
* lock
|
|
*
|
|
* @idmap: idmap of the mount of the target inode
|
|
* @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 mnt_idmap *idmap,
|
|
struct dentry *dentry, const char *name,
|
|
struct inode **delegated_inode)
|
|
{
|
|
struct inode *inode = dentry->d_inode;
|
|
int error;
|
|
|
|
error = xattr_permission(idmap, inode, name, MAY_WRITE);
|
|
if (error)
|
|
return error;
|
|
|
|
error = security_inode_removexattr(idmap, dentry, name);
|
|
if (error)
|
|
goto out;
|
|
|
|
error = try_break_deleg(inode, delegated_inode);
|
|
if (error)
|
|
goto out;
|
|
|
|
error = __vfs_removexattr(idmap, 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 mnt_idmap *idmap, 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(idmap, 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
|
|
*/
|
|
|
|
int setxattr_copy(const char __user *name, struct xattr_ctx *ctx)
|
|
{
|
|
int error;
|
|
|
|
if (ctx->flags & ~(XATTR_CREATE|XATTR_REPLACE))
|
|
return -EINVAL;
|
|
|
|
error = strncpy_from_user(ctx->kname->name, name,
|
|
sizeof(ctx->kname->name));
|
|
if (error == 0 || error == sizeof(ctx->kname->name))
|
|
return -ERANGE;
|
|
if (error < 0)
|
|
return error;
|
|
|
|
error = 0;
|
|
if (ctx->size) {
|
|
if (ctx->size > XATTR_SIZE_MAX)
|
|
return -E2BIG;
|
|
|
|
ctx->kvalue = vmemdup_user(ctx->cvalue, ctx->size);
|
|
if (IS_ERR(ctx->kvalue)) {
|
|
error = PTR_ERR(ctx->kvalue);
|
|
ctx->kvalue = NULL;
|
|
}
|
|
}
|
|
|
|
return error;
|
|
}
|
|
|
|
int do_setxattr(struct mnt_idmap *idmap, struct dentry *dentry,
|
|
struct xattr_ctx *ctx)
|
|
{
|
|
if (is_posix_acl_xattr(ctx->kname->name))
|
|
return do_set_acl(idmap, dentry, ctx->kname->name,
|
|
ctx->kvalue, ctx->size);
|
|
|
|
return vfs_setxattr(idmap, dentry, ctx->kname->name,
|
|
ctx->kvalue, ctx->size, ctx->flags);
|
|
}
|
|
|
|
static long
|
|
setxattr(struct mnt_idmap *idmap, struct dentry *d,
|
|
const char __user *name, const void __user *value, size_t size,
|
|
int flags)
|
|
{
|
|
struct xattr_name kname;
|
|
struct xattr_ctx ctx = {
|
|
.cvalue = value,
|
|
.kvalue = NULL,
|
|
.size = size,
|
|
.kname = &kname,
|
|
.flags = flags,
|
|
};
|
|
int error;
|
|
|
|
error = setxattr_copy(name, &ctx);
|
|
if (error)
|
|
return error;
|
|
|
|
error = do_setxattr(idmap, d, &ctx);
|
|
|
|
kvfree(ctx.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_idmap(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_idmap(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
|
|
*/
|
|
ssize_t
|
|
do_getxattr(struct mnt_idmap *idmap, struct dentry *d,
|
|
struct xattr_ctx *ctx)
|
|
{
|
|
ssize_t error;
|
|
char *kname = ctx->kname->name;
|
|
|
|
if (ctx->size) {
|
|
if (ctx->size > XATTR_SIZE_MAX)
|
|
ctx->size = XATTR_SIZE_MAX;
|
|
ctx->kvalue = kvzalloc(ctx->size, GFP_KERNEL);
|
|
if (!ctx->kvalue)
|
|
return -ENOMEM;
|
|
}
|
|
|
|
if (is_posix_acl_xattr(ctx->kname->name))
|
|
error = do_get_acl(idmap, d, kname, ctx->kvalue, ctx->size);
|
|
else
|
|
error = vfs_getxattr(idmap, d, kname, ctx->kvalue, ctx->size);
|
|
if (error > 0) {
|
|
if (ctx->size && copy_to_user(ctx->value, ctx->kvalue, error))
|
|
error = -EFAULT;
|
|
} else if (error == -ERANGE && ctx->size >= XATTR_SIZE_MAX) {
|
|
/* The file system tried to returned a value bigger
|
|
than XATTR_SIZE_MAX bytes. Not possible. */
|
|
error = -E2BIG;
|
|
}
|
|
|
|
return error;
|
|
}
|
|
|
|
static ssize_t
|
|
getxattr(struct mnt_idmap *idmap, struct dentry *d,
|
|
const char __user *name, void __user *value, size_t size)
|
|
{
|
|
ssize_t error;
|
|
struct xattr_name kname;
|
|
struct xattr_ctx ctx = {
|
|
.value = value,
|
|
.kvalue = NULL,
|
|
.size = size,
|
|
.kname = &kname,
|
|
.flags = 0,
|
|
};
|
|
|
|
error = strncpy_from_user(kname.name, name, sizeof(kname.name));
|
|
if (error == 0 || error == sizeof(kname.name))
|
|
error = -ERANGE;
|
|
if (error < 0)
|
|
return error;
|
|
|
|
error = do_getxattr(idmap, d, &ctx);
|
|
|
|
kvfree(ctx.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_idmap(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_idmap(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 mnt_idmap *idmap, 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;
|
|
|
|
if (is_posix_acl_xattr(kname))
|
|
return vfs_remove_acl(idmap, d, kname);
|
|
|
|
return vfs_removexattr(idmap, 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_idmap(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_idmap(f.file),
|
|
f.file->f_path.dentry, name);
|
|
mnt_drop_write_file(f.file);
|
|
}
|
|
fdput(f);
|
|
return error;
|
|
}
|
|
|
|
int xattr_list_one(char **buffer, ssize_t *remaining_size, const char *name)
|
|
{
|
|
size_t len;
|
|
|
|
len = strlen(name) + 1;
|
|
if (*buffer) {
|
|
if (*remaining_size < len)
|
|
return -ERANGE;
|
|
memcpy(*buffer, name, len);
|
|
*buffer += len;
|
|
}
|
|
*remaining_size -= len;
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* generic_listxattr - run through a dentry's xattr list() operations
|
|
* @dentry: dentry to list the xattrs
|
|
* @buffer: result buffer
|
|
* @buffer_size: size of @buffer
|
|
*
|
|
* Combine the results of the list() operation from every xattr_handler in the
|
|
* xattr_handler stack.
|
|
*
|
|
* Note that this will not include the entries for POSIX ACLs.
|
|
*/
|
|
ssize_t
|
|
generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
|
|
{
|
|
const struct xattr_handler *handler, **handlers = dentry->d_sb->s_xattr;
|
|
ssize_t remaining_size = buffer_size;
|
|
int err = 0;
|
|
|
|
for_each_xattr_handler(handlers, handler) {
|
|
if (!handler->name || (handler->list && !handler->list(dentry)))
|
|
continue;
|
|
err = xattr_list_one(&buffer, &remaining_size, handler->name);
|
|
if (err)
|
|
return err;
|
|
}
|
|
|
|
return err ? err : buffer_size - remaining_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);
|
|
|
|
/**
|
|
* free_simple_xattr - free an xattr object
|
|
* @xattr: the xattr object
|
|
*
|
|
* Free the xattr object. Can handle @xattr being NULL.
|
|
*/
|
|
static inline void free_simple_xattr(struct simple_xattr *xattr)
|
|
{
|
|
if (xattr)
|
|
kfree(xattr->name);
|
|
kvfree(xattr);
|
|
}
|
|
|
|
/**
|
|
* simple_xattr_alloc - allocate new xattr object
|
|
* @value: value of the xattr object
|
|
* @size: size of @value
|
|
*
|
|
* Allocate a new xattr object and initialize respective members. The caller is
|
|
* responsible for handling the name of the xattr.
|
|
*
|
|
* Return: On success a new xattr object is returned. On failure NULL is
|
|
* returned.
|
|
*/
|
|
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;
|
|
}
|
|
|
|
/**
|
|
* rbtree_simple_xattr_cmp - compare xattr name with current rbtree xattr entry
|
|
* @key: xattr name
|
|
* @node: current node
|
|
*
|
|
* Compare the xattr name with the xattr name attached to @node in the rbtree.
|
|
*
|
|
* Return: Negative value if continuing left, positive if continuing right, 0
|
|
* if the xattr attached to @node matches @key.
|
|
*/
|
|
static int rbtree_simple_xattr_cmp(const void *key, const struct rb_node *node)
|
|
{
|
|
const char *xattr_name = key;
|
|
const struct simple_xattr *xattr;
|
|
|
|
xattr = rb_entry(node, struct simple_xattr, rb_node);
|
|
return strcmp(xattr->name, xattr_name);
|
|
}
|
|
|
|
/**
|
|
* rbtree_simple_xattr_node_cmp - compare two xattr rbtree nodes
|
|
* @new_node: new node
|
|
* @node: current node
|
|
*
|
|
* Compare the xattr attached to @new_node with the xattr attached to @node.
|
|
*
|
|
* Return: Negative value if continuing left, positive if continuing right, 0
|
|
* if the xattr attached to @new_node matches the xattr attached to @node.
|
|
*/
|
|
static int rbtree_simple_xattr_node_cmp(struct rb_node *new_node,
|
|
const struct rb_node *node)
|
|
{
|
|
struct simple_xattr *xattr;
|
|
xattr = rb_entry(new_node, struct simple_xattr, rb_node);
|
|
return rbtree_simple_xattr_cmp(xattr->name, node);
|
|
}
|
|
|
|
/**
|
|
* simple_xattr_get - get an xattr object
|
|
* @xattrs: the header of the xattr object
|
|
* @name: the name of the xattr to retrieve
|
|
* @buffer: the buffer to store the value into
|
|
* @size: the size of @buffer
|
|
*
|
|
* Try to find and retrieve the xattr object associated with @name.
|
|
* If @buffer is provided store the value of @xattr in @buffer
|
|
* otherwise just return the length. The size of @buffer is limited
|
|
* to XATTR_SIZE_MAX which currently is 65536.
|
|
*
|
|
* Return: On success the length of the xattr value is returned. On error a
|
|
* negative error code is returned.
|
|
*/
|
|
int simple_xattr_get(struct simple_xattrs *xattrs, const char *name,
|
|
void *buffer, size_t size)
|
|
{
|
|
struct simple_xattr *xattr = NULL;
|
|
struct rb_node *rbp;
|
|
int ret = -ENODATA;
|
|
|
|
read_lock(&xattrs->lock);
|
|
rbp = rb_find(name, &xattrs->rb_root, rbtree_simple_xattr_cmp);
|
|
if (rbp) {
|
|
xattr = rb_entry(rbp, struct simple_xattr, rb_node);
|
|
ret = xattr->size;
|
|
if (buffer) {
|
|
if (size < xattr->size)
|
|
ret = -ERANGE;
|
|
else
|
|
memcpy(buffer, xattr->value, xattr->size);
|
|
}
|
|
}
|
|
read_unlock(&xattrs->lock);
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* simple_xattr_set - set an xattr object
|
|
* @xattrs: the header of the xattr object
|
|
* @name: the name of the xattr to retrieve
|
|
* @value: the value to store along the xattr
|
|
* @size: the size of @value
|
|
* @flags: the flags determining how to set the xattr
|
|
* @removed_size: the size of the removed xattr
|
|
*
|
|
* Set a new xattr object.
|
|
* If @value is passed a new xattr object will be allocated. If XATTR_REPLACE
|
|
* is specified in @flags a matching xattr object for @name must already exist.
|
|
* If it does it will be replaced with the new xattr object. If it doesn't we
|
|
* fail. If XATTR_CREATE is specified and a matching xattr does already exist
|
|
* we fail. If it doesn't we create a new xattr. If @flags is zero we simply
|
|
* insert the new xattr replacing any existing one.
|
|
*
|
|
* If @value is empty and a matching xattr object is found we delete it if
|
|
* XATTR_REPLACE is specified in @flags or @flags is zero.
|
|
*
|
|
* If @value is empty and no matching xattr object for @name is found we do
|
|
* nothing if XATTR_CREATE is specified in @flags or @flags is zero. For
|
|
* XATTR_REPLACE we fail as mentioned above.
|
|
*
|
|
* Return: On success zero and on error a negative error code is returned.
|
|
*/
|
|
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 = NULL, *new_xattr = NULL;
|
|
struct rb_node *parent = NULL, **rbp;
|
|
int err = 0, ret;
|
|
|
|
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) {
|
|
free_simple_xattr(new_xattr);
|
|
return -ENOMEM;
|
|
}
|
|
}
|
|
|
|
write_lock(&xattrs->lock);
|
|
rbp = &xattrs->rb_root.rb_node;
|
|
while (*rbp) {
|
|
parent = *rbp;
|
|
ret = rbtree_simple_xattr_cmp(name, *rbp);
|
|
if (ret < 0)
|
|
rbp = &(*rbp)->rb_left;
|
|
else if (ret > 0)
|
|
rbp = &(*rbp)->rb_right;
|
|
else
|
|
xattr = rb_entry(*rbp, struct simple_xattr, rb_node);
|
|
if (xattr)
|
|
break;
|
|
}
|
|
|
|
if (xattr) {
|
|
/* Fail if XATTR_CREATE is requested and the xattr exists. */
|
|
if (flags & XATTR_CREATE) {
|
|
err = -EEXIST;
|
|
goto out_unlock;
|
|
}
|
|
|
|
if (new_xattr)
|
|
rb_replace_node(&xattr->rb_node, &new_xattr->rb_node,
|
|
&xattrs->rb_root);
|
|
else
|
|
rb_erase(&xattr->rb_node, &xattrs->rb_root);
|
|
if (!err && removed_size)
|
|
*removed_size = xattr->size;
|
|
} else {
|
|
/* Fail if XATTR_REPLACE is requested but no xattr is found. */
|
|
if (flags & XATTR_REPLACE) {
|
|
err = -ENODATA;
|
|
goto out_unlock;
|
|
}
|
|
|
|
/*
|
|
* If XATTR_CREATE or no flags are specified together with a
|
|
* new value simply insert it.
|
|
*/
|
|
if (new_xattr) {
|
|
rb_link_node(&new_xattr->rb_node, parent, rbp);
|
|
rb_insert_color(&new_xattr->rb_node, &xattrs->rb_root);
|
|
}
|
|
|
|
/*
|
|
* If XATTR_CREATE or no flags are specified and neither an
|
|
* old or new xattr exist then we don't need to do anything.
|
|
*/
|
|
}
|
|
|
|
out_unlock:
|
|
write_unlock(&xattrs->lock);
|
|
if (err)
|
|
free_simple_xattr(new_xattr);
|
|
else
|
|
free_simple_xattr(xattr);
|
|
return err;
|
|
|
|
}
|
|
|
|
static bool xattr_is_trusted(const char *name)
|
|
{
|
|
return !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN);
|
|
}
|
|
|
|
/**
|
|
* simple_xattr_list - list all xattr objects
|
|
* @inode: inode from which to get the xattrs
|
|
* @xattrs: the header of the xattr object
|
|
* @buffer: the buffer to store all xattrs into
|
|
* @size: the size of @buffer
|
|
*
|
|
* List all xattrs associated with @inode. If @buffer is NULL we returned
|
|
* the required size of the buffer. If @buffer is provided we store the
|
|
* xattrs value into it provided it is big enough.
|
|
*
|
|
* Note, the number of xattr names that can be listed with listxattr(2) is
|
|
* limited to XATTR_LIST_MAX aka 65536 bytes. If a larger buffer is passed
|
|
* then vfs_listxattr() caps it to XATTR_LIST_MAX and if more xattr names
|
|
* are found it will return -E2BIG.
|
|
*
|
|
* Return: On success the required size or the size of the copied xattrs is
|
|
* returned. On error a negative error code is returned.
|
|
*/
|
|
ssize_t simple_xattr_list(struct inode *inode, struct simple_xattrs *xattrs,
|
|
char *buffer, size_t size)
|
|
{
|
|
bool trusted = ns_capable_noaudit(&init_user_ns, CAP_SYS_ADMIN);
|
|
struct simple_xattr *xattr;
|
|
struct rb_node *rbp;
|
|
ssize_t remaining_size = size;
|
|
int err = 0;
|
|
|
|
err = posix_acl_listxattr(inode, &buffer, &remaining_size);
|
|
if (err)
|
|
return err;
|
|
|
|
read_lock(&xattrs->lock);
|
|
for (rbp = rb_first(&xattrs->rb_root); rbp; rbp = rb_next(rbp)) {
|
|
xattr = rb_entry(rbp, struct simple_xattr, rb_node);
|
|
|
|
/* 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;
|
|
}
|
|
read_unlock(&xattrs->lock);
|
|
|
|
return err ? err : size - remaining_size;
|
|
}
|
|
|
|
/**
|
|
* rbtree_simple_xattr_less - compare two xattr rbtree nodes
|
|
* @new_node: new node
|
|
* @node: current node
|
|
*
|
|
* Compare the xattr attached to @new_node with the xattr attached to @node.
|
|
* Note that this function technically tolerates duplicate entries.
|
|
*
|
|
* Return: True if insertion point in the rbtree is found.
|
|
*/
|
|
static bool rbtree_simple_xattr_less(struct rb_node *new_node,
|
|
const struct rb_node *node)
|
|
{
|
|
return rbtree_simple_xattr_node_cmp(new_node, node) < 0;
|
|
}
|
|
|
|
/**
|
|
* simple_xattr_add - add xattr objects
|
|
* @xattrs: the header of the xattr object
|
|
* @new_xattr: the xattr object to add
|
|
*
|
|
* Add an xattr object to @xattrs. This assumes no replacement or removal
|
|
* of matching xattrs is wanted. Should only be called during inode
|
|
* initialization when a few distinct initial xattrs are supposed to be set.
|
|
*/
|
|
void simple_xattr_add(struct simple_xattrs *xattrs,
|
|
struct simple_xattr *new_xattr)
|
|
{
|
|
write_lock(&xattrs->lock);
|
|
rb_add(&new_xattr->rb_node, &xattrs->rb_root, rbtree_simple_xattr_less);
|
|
write_unlock(&xattrs->lock);
|
|
}
|
|
|
|
/**
|
|
* simple_xattrs_init - initialize new xattr header
|
|
* @xattrs: header to initialize
|
|
*
|
|
* Initialize relevant fields of a an xattr header.
|
|
*/
|
|
void simple_xattrs_init(struct simple_xattrs *xattrs)
|
|
{
|
|
xattrs->rb_root = RB_ROOT;
|
|
rwlock_init(&xattrs->lock);
|
|
}
|
|
|
|
/**
|
|
* simple_xattrs_free - free xattrs
|
|
* @xattrs: xattr header whose xattrs to destroy
|
|
*
|
|
* Destroy all xattrs in @xattr. When this is called no one can hold a
|
|
* reference to any of the xattrs anymore.
|
|
*/
|
|
void simple_xattrs_free(struct simple_xattrs *xattrs)
|
|
{
|
|
struct rb_node *rbp;
|
|
|
|
rbp = rb_first(&xattrs->rb_root);
|
|
while (rbp) {
|
|
struct simple_xattr *xattr;
|
|
struct rb_node *rbp_next;
|
|
|
|
rbp_next = rb_next(rbp);
|
|
xattr = rb_entry(rbp, struct simple_xattr, rb_node);
|
|
rb_erase(&xattr->rb_node, &xattrs->rb_root);
|
|
free_simple_xattr(xattr);
|
|
rbp = rbp_next;
|
|
}
|
|
}
|