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![Miklos Szeredi](/assets/img/avatar_default.png)
cap_convert_nscap() does permission checking as well as conversion of the xattr value conditionally based on fs's user-ns. This is needed by overlayfs and probably other layered fs (ecryptfs) and is what vfs_foo() is supposed to do anyway. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Acked-by: James Morris <jamorris@linux.microsoft.com>
1103 lines
26 KiB
C
1103 lines
26 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/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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/*
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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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* 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 inode *inode, 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
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* filesystem or on an immutable / append-only inode.
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*/
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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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/*
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* Updating an xattr will likely cause i_uid and i_gid
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* to be writen back improperly if their true value is
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* unknown to the vfs.
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*/
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if (HAS_UNMAPPED_ID(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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/*
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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) && !inode_owner_or_capable(inode))
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return -EPERM;
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}
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return inode_permission(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))
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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_supported_namespace);
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int
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__vfs_setxattr(struct dentry *dentry, struct inode *inode, const char *name,
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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);
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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, dentry, inode, name, value, 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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* @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 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(dentry, inode, name, value, 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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* @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 dentry *dentry, const char *name,
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const void *value, size_t size, int flags,
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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(inode, name, MAY_WRITE);
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if (error)
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return error;
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error = security_inode_setxattr(dentry, name, value, size, 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(dentry, name, value, 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 dentry *dentry, const char *name, const void *value,
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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(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(dentry, name, value, size, flags,
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&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 inode *inode, const char *name, void *value,
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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(inode, name, &buffer, false);
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goto out_noalloc;
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}
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len = security_inode_getsecurity(inode, name, &buffer, 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.
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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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ssize_t
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vfs_getxattr_alloc(struct dentry *dentry, const char *name, char **xattr_value,
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size_t xattr_size, 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(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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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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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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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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ssize_t
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vfs_getxattr(struct dentry *dentry, 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(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;
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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(inode, suffix, value, size);
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/*
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* Only overwrite the return value if a security module
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* is actually active.
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*/
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if (ret == -EOPNOTSUPP)
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goto nolsm;
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return ret;
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}
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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);
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ssize_t
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vfs_listxattr(struct dentry *dentry, char *list, size_t size)
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{
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struct inode *inode = d_inode(dentry);
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ssize_t error;
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error = security_inode_listxattr(dentry);
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if (error)
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return error;
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if (inode->i_op->listxattr && (inode->i_opflags & IOP_XATTR)) {
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error = inode->i_op->listxattr(dentry, list, size);
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} else {
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error = security_inode_listsecurity(inode, list, size);
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if (size && error > size)
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error = -ERANGE;
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}
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return error;
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}
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EXPORT_SYMBOL_GPL(vfs_listxattr);
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int
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__vfs_removexattr(struct dentry *dentry, const char *name)
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{
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struct inode *inode = d_inode(dentry);
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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);
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if (!handler->set)
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return -EOPNOTSUPP;
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return handler->set(handler, dentry, inode, name, NULL, 0, XATTR_REPLACE);
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}
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EXPORT_SYMBOL(__vfs_removexattr);
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/**
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* __vfs_removexattr_locked - set an extended attribute while holding the inode
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* lock
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*
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* @dentry: object to perform setxattr on
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* @name: name of xattr to remove
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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_removexattr_locked(struct dentry *dentry, const char *name,
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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(inode, name, MAY_WRITE);
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if (error)
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return error;
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error = security_inode_removexattr(dentry, name);
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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_removexattr(dentry, name);
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if (!error) {
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fsnotify_xattr(dentry);
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evm_inode_post_removexattr(dentry, name);
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}
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out:
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return error;
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}
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EXPORT_SYMBOL_GPL(__vfs_removexattr_locked);
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int
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vfs_removexattr(struct dentry *dentry, const char *name)
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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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int error;
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retry_deleg:
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inode_lock(inode);
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error = __vfs_removexattr_locked(dentry, name, &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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return error;
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}
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EXPORT_SYMBOL_GPL(vfs_removexattr);
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/*
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* Extended attribute SET operations
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*/
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static long
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setxattr(struct dentry *d, const char __user *name, const void __user *value,
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size_t size, int flags)
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{
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int error;
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|
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(kvalue, size);
|
|
}
|
|
|
|
error = vfs_setxattr(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(path.dentry, name, value, size, flags);
|
|
mnt_drop_write(path.mnt);
|
|
}
|
|
path_put(&path);
|
|
if (retry_estale(error, lookup_flags)) {
|
|
lookup_flags |= LOOKUP_REVAL;
|
|
goto retry;
|
|
}
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE5(setxattr, const char __user *, pathname,
|
|
const char __user *, name, const void __user *, value,
|
|
size_t, size, int, flags)
|
|
{
|
|
return path_setxattr(pathname, name, value, size, flags, LOOKUP_FOLLOW);
|
|
}
|
|
|
|
SYSCALL_DEFINE5(lsetxattr, const char __user *, pathname,
|
|
const char __user *, name, const void __user *, value,
|
|
size_t, size, int, flags)
|
|
{
|
|
return path_setxattr(pathname, name, value, size, flags, 0);
|
|
}
|
|
|
|
SYSCALL_DEFINE5(fsetxattr, int, fd, const char __user *, name,
|
|
const void __user *,value, size_t, size, int, flags)
|
|
{
|
|
struct fd f = fdget(fd);
|
|
int error = -EBADF;
|
|
|
|
if (!f.file)
|
|
return error;
|
|
audit_file(f.file);
|
|
error = mnt_want_write_file(f.file);
|
|
if (!error) {
|
|
error = setxattr(f.file->f_path.dentry, name, value, size, flags);
|
|
mnt_drop_write_file(f.file);
|
|
}
|
|
fdput(f);
|
|
return error;
|
|
}
|
|
|
|
/*
|
|
* Extended attribute GET operations
|
|
*/
|
|
static ssize_t
|
|
getxattr(struct dentry *d, const char __user *name, void __user *value,
|
|
size_t size)
|
|
{
|
|
ssize_t error;
|
|
void *kvalue = NULL;
|
|
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(d, kname, kvalue, size);
|
|
if (error > 0) {
|
|
if ((strcmp(kname, XATTR_NAME_POSIX_ACL_ACCESS) == 0) ||
|
|
(strcmp(kname, XATTR_NAME_POSIX_ACL_DEFAULT) == 0))
|
|
posix_acl_fix_xattr_to_user(kvalue, 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(path.dentry, name, value, size);
|
|
path_put(&path);
|
|
if (retry_estale(error, lookup_flags)) {
|
|
lookup_flags |= LOOKUP_REVAL;
|
|
goto retry;
|
|
}
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE4(getxattr, const char __user *, pathname,
|
|
const char __user *, name, void __user *, value, size_t, size)
|
|
{
|
|
return path_getxattr(pathname, name, value, size, LOOKUP_FOLLOW);
|
|
}
|
|
|
|
SYSCALL_DEFINE4(lgetxattr, const char __user *, pathname,
|
|
const char __user *, name, void __user *, value, size_t, size)
|
|
{
|
|
return path_getxattr(pathname, name, value, size, 0);
|
|
}
|
|
|
|
SYSCALL_DEFINE4(fgetxattr, int, fd, const char __user *, name,
|
|
void __user *, value, size_t, size)
|
|
{
|
|
struct fd f = fdget(fd);
|
|
ssize_t error = -EBADF;
|
|
|
|
if (!f.file)
|
|
return error;
|
|
audit_file(f.file);
|
|
error = getxattr(f.file->f_path.dentry, name, value, size);
|
|
fdput(f);
|
|
return error;
|
|
}
|
|
|
|
/*
|
|
* Extended attribute LIST operations
|
|
*/
|
|
static ssize_t
|
|
listxattr(struct dentry *d, char __user *list, size_t size)
|
|
{
|
|
ssize_t error;
|
|
char *klist = NULL;
|
|
|
|
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 dentry *d, const char __user *name)
|
|
{
|
|
int error;
|
|
char kname[XATTR_NAME_MAX + 1];
|
|
|
|
error = strncpy_from_user(kname, name, sizeof(kname));
|
|
if (error == 0 || error == sizeof(kname))
|
|
error = -ERANGE;
|
|
if (error < 0)
|
|
return error;
|
|
|
|
return vfs_removexattr(d, kname);
|
|
}
|
|
|
|
static int path_removexattr(const char __user *pathname,
|
|
const char __user *name, unsigned int lookup_flags)
|
|
{
|
|
struct path path;
|
|
int error;
|
|
retry:
|
|
error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
|
|
if (error)
|
|
return error;
|
|
error = mnt_want_write(path.mnt);
|
|
if (!error) {
|
|
error = removexattr(path.dentry, name);
|
|
mnt_drop_write(path.mnt);
|
|
}
|
|
path_put(&path);
|
|
if (retry_estale(error, lookup_flags)) {
|
|
lookup_flags |= LOOKUP_REVAL;
|
|
goto retry;
|
|
}
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE2(removexattr, const char __user *, pathname,
|
|
const char __user *, name)
|
|
{
|
|
return path_removexattr(pathname, name, LOOKUP_FOLLOW);
|
|
}
|
|
|
|
SYSCALL_DEFINE2(lremovexattr, const char __user *, pathname,
|
|
const char __user *, name)
|
|
{
|
|
return path_removexattr(pathname, name, 0);
|
|
}
|
|
|
|
SYSCALL_DEFINE2(fremovexattr, int, fd, const char __user *, name)
|
|
{
|
|
struct fd f = fdget(fd);
|
|
int error = -EBADF;
|
|
|
|
if (!f.file)
|
|
return error;
|
|
audit_file(f.file);
|
|
error = mnt_want_write_file(f.file);
|
|
if (!error) {
|
|
error = removexattr(f.file->f_path.dentry, name);
|
|
mnt_drop_write_file(f.file);
|
|
}
|
|
fdput(f);
|
|
return error;
|
|
}
|
|
|
|
/*
|
|
* 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);
|
|
}
|