linux/fs/9p/xattr.c
Christian Brauner 39f60c1cce
fs: port xattr to mnt_idmap
Convert to struct mnt_idmap.

Last cycle we merged the necessary infrastructure in
256c8aed2b ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.

Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.

Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.

Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-01-19 09:24:28 +01:00

195 lines
4.9 KiB
C

// SPDX-License-Identifier: LGPL-2.1
/*
* Copyright IBM Corporation, 2010
* Author Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
*/
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/uio.h>
#include <linux/posix_acl_xattr.h>
#include <net/9p/9p.h>
#include <net/9p/client.h>
#include "fid.h"
#include "xattr.h"
ssize_t v9fs_fid_xattr_get(struct p9_fid *fid, const char *name,
void *buffer, size_t buffer_size)
{
ssize_t retval;
u64 attr_size;
struct p9_fid *attr_fid;
struct kvec kvec = {.iov_base = buffer, .iov_len = buffer_size};
struct iov_iter to;
int err;
iov_iter_kvec(&to, ITER_DEST, &kvec, 1, buffer_size);
attr_fid = p9_client_xattrwalk(fid, name, &attr_size);
if (IS_ERR(attr_fid)) {
retval = PTR_ERR(attr_fid);
p9_debug(P9_DEBUG_VFS, "p9_client_attrwalk failed %zd\n",
retval);
return retval;
}
if (attr_size > buffer_size) {
if (!buffer_size) /* request to get the attr_size */
retval = attr_size;
else
retval = -ERANGE;
} else {
iov_iter_truncate(&to, attr_size);
retval = p9_client_read(attr_fid, 0, &to, &err);
if (err)
retval = err;
}
p9_fid_put(attr_fid);
return retval;
}
/*
* v9fs_xattr_get()
*
* Copy an extended attribute into the buffer
* provided, or compute the buffer size required.
* Buffer is NULL to compute the size of the buffer required.
*
* Returns a negative error number on failure, or the number of bytes
* used / required on success.
*/
ssize_t v9fs_xattr_get(struct dentry *dentry, const char *name,
void *buffer, size_t buffer_size)
{
struct p9_fid *fid;
int ret;
p9_debug(P9_DEBUG_VFS, "name = %s value_len = %zu\n",
name, buffer_size);
fid = v9fs_fid_lookup(dentry);
if (IS_ERR(fid))
return PTR_ERR(fid);
ret = v9fs_fid_xattr_get(fid, name, buffer, buffer_size);
p9_fid_put(fid);
return ret;
}
/*
* v9fs_xattr_set()
*
* Create, replace or remove an extended attribute for this inode. Buffer
* is NULL to remove an existing extended attribute, and non-NULL to
* either replace an existing extended attribute, or create a new extended
* attribute. The flags XATTR_REPLACE and XATTR_CREATE
* specify that an extended attribute must exist and must not exist
* previous to the call, respectively.
*
* Returns 0, or a negative error number on failure.
*/
int v9fs_xattr_set(struct dentry *dentry, const char *name,
const void *value, size_t value_len, int flags)
{
int ret;
struct p9_fid *fid;
fid = v9fs_fid_lookup(dentry);
if (IS_ERR(fid))
return PTR_ERR(fid);
ret = v9fs_fid_xattr_set(fid, name, value, value_len, flags);
p9_fid_put(fid);
return ret;
}
int v9fs_fid_xattr_set(struct p9_fid *fid, const char *name,
const void *value, size_t value_len, int flags)
{
struct kvec kvec = {.iov_base = (void *)value, .iov_len = value_len};
struct iov_iter from;
int retval, err;
iov_iter_kvec(&from, ITER_SOURCE, &kvec, 1, value_len);
p9_debug(P9_DEBUG_VFS, "name = %s value_len = %zu flags = %d\n",
name, value_len, flags);
/* Clone it */
fid = clone_fid(fid);
if (IS_ERR(fid))
return PTR_ERR(fid);
/*
* On success fid points to xattr
*/
retval = p9_client_xattrcreate(fid, name, value_len, flags);
if (retval < 0)
p9_debug(P9_DEBUG_VFS, "p9_client_xattrcreate failed %d\n",
retval);
else
p9_client_write(fid, 0, &from, &retval);
err = p9_fid_put(fid);
if (!retval && err)
retval = err;
return retval;
}
ssize_t v9fs_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
{
return v9fs_xattr_get(dentry, NULL, buffer, buffer_size);
}
static int v9fs_xattr_handler_get(const struct xattr_handler *handler,
struct dentry *dentry, struct inode *inode,
const char *name, void *buffer, size_t size)
{
const char *full_name = xattr_full_name(handler, name);
return v9fs_xattr_get(dentry, full_name, buffer, size);
}
static int v9fs_xattr_handler_set(const struct xattr_handler *handler,
struct mnt_idmap *idmap,
struct dentry *dentry, struct inode *inode,
const char *name, const void *value,
size_t size, int flags)
{
const char *full_name = xattr_full_name(handler, name);
return v9fs_xattr_set(dentry, full_name, value, size, flags);
}
static struct xattr_handler v9fs_xattr_user_handler = {
.prefix = XATTR_USER_PREFIX,
.get = v9fs_xattr_handler_get,
.set = v9fs_xattr_handler_set,
};
static struct xattr_handler v9fs_xattr_trusted_handler = {
.prefix = XATTR_TRUSTED_PREFIX,
.get = v9fs_xattr_handler_get,
.set = v9fs_xattr_handler_set,
};
#ifdef CONFIG_9P_FS_SECURITY
static struct xattr_handler v9fs_xattr_security_handler = {
.prefix = XATTR_SECURITY_PREFIX,
.get = v9fs_xattr_handler_get,
.set = v9fs_xattr_handler_set,
};
#endif
const struct xattr_handler *v9fs_xattr_handlers[] = {
&v9fs_xattr_user_handler,
&v9fs_xattr_trusted_handler,
#ifdef CONFIG_FS_POSIX_ACL
&posix_acl_access_xattr_handler,
&posix_acl_default_xattr_handler,
#endif
#ifdef CONFIG_9P_FS_SECURITY
&v9fs_xattr_security_handler,
#endif
NULL
};