linux/fs/afs/xattr.c
David Howells a7889c6320 afs: Stop listxattr() from listing "afs.*" attributes
afs_listxattr() lists all the available special afs xattrs (i.e. those in
the "afs.*" space), no matter what type of server we're dealing with.  But
OpenAFS servers, for example, cannot deal with some of the extra-capable
attributes that AuriStor (YFS) servers provide.  Unfortunately, the
presence of the afs.yfs.* attributes causes errors[1] for anything that
tries to read them if the server is of the wrong type.

Fix the problem by removing afs_listxattr() so that none of the special
xattrs are listed (AFS doesn't support xattrs).  It does mean, however,
that getfattr won't list them, though they can still be accessed with
getxattr() and setxattr().

This can be tested with something like:

	getfattr -d -m ".*" /afs/example.com/path/to/file

With this change, none of the afs.* attributes should be visible.

Changes:
ver #2:
 - Hide all of the afs.* xattrs, not just the ACL ones.

Fixes: ae46578b96 ("afs: Get YFS ACLs and information through xattrs")
Reported-by: Gaja Sophie Peters <gaja.peters@math.uni-hamburg.de>
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Gaja Sophie Peters <gaja.peters@math.uni-hamburg.de>
Reviewed-by: Jeffrey Altman <jaltman@auristor.com>
Reviewed-by: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Link: http://lists.infradead.org/pipermail/linux-afs/2021-March/003502.html [1]
Link: http://lists.infradead.org/pipermail/linux-afs/2021-March/003567.html # v1
Link: http://lists.infradead.org/pipermail/linux-afs/2021-March/003573.html # v2
2021-03-15 17:09:54 +00:00

364 lines
8.4 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/* Extended attribute handling for AFS. We use xattrs to get and set metadata
* instead of providing pioctl().
*
* Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*/
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/xattr.h>
#include "internal.h"
/*
* Deal with the result of a successful fetch ACL operation.
*/
static void afs_acl_success(struct afs_operation *op)
{
afs_vnode_commit_status(op, &op->file[0]);
}
static void afs_acl_put(struct afs_operation *op)
{
kfree(op->acl);
}
static const struct afs_operation_ops afs_fetch_acl_operation = {
.issue_afs_rpc = afs_fs_fetch_acl,
.success = afs_acl_success,
.put = afs_acl_put,
};
/*
* Get a file's ACL.
*/
static int afs_xattr_get_acl(const struct xattr_handler *handler,
struct dentry *dentry,
struct inode *inode, const char *name,
void *buffer, size_t size)
{
struct afs_operation *op;
struct afs_vnode *vnode = AFS_FS_I(inode);
struct afs_acl *acl = NULL;
int ret;
op = afs_alloc_operation(NULL, vnode->volume);
if (IS_ERR(op))
return -ENOMEM;
afs_op_set_vnode(op, 0, vnode);
op->ops = &afs_fetch_acl_operation;
afs_begin_vnode_operation(op);
afs_wait_for_operation(op);
acl = op->acl;
op->acl = NULL;
ret = afs_put_operation(op);
if (ret == 0) {
ret = acl->size;
if (size > 0) {
if (acl->size <= size)
memcpy(buffer, acl->data, acl->size);
else
ret = -ERANGE;
}
}
kfree(acl);
return ret;
}
static bool afs_make_acl(struct afs_operation *op,
const void *buffer, size_t size)
{
struct afs_acl *acl;
acl = kmalloc(sizeof(*acl) + size, GFP_KERNEL);
if (!acl) {
afs_op_nomem(op);
return false;
}
acl->size = size;
memcpy(acl->data, buffer, size);
op->acl = acl;
return true;
}
static const struct afs_operation_ops afs_store_acl_operation = {
.issue_afs_rpc = afs_fs_store_acl,
.success = afs_acl_success,
.put = afs_acl_put,
};
/*
* Set a file's AFS3 ACL.
*/
static int afs_xattr_set_acl(const struct xattr_handler *handler,
struct user_namespace *mnt_userns,
struct dentry *dentry,
struct inode *inode, const char *name,
const void *buffer, size_t size, int flags)
{
struct afs_operation *op;
struct afs_vnode *vnode = AFS_FS_I(inode);
if (flags == XATTR_CREATE)
return -EINVAL;
op = afs_alloc_operation(NULL, vnode->volume);
if (IS_ERR(op))
return -ENOMEM;
afs_op_set_vnode(op, 0, vnode);
if (!afs_make_acl(op, buffer, size))
return afs_put_operation(op);
op->ops = &afs_store_acl_operation;
return afs_do_sync_operation(op);
}
static const struct xattr_handler afs_xattr_afs_acl_handler = {
.name = "afs.acl",
.get = afs_xattr_get_acl,
.set = afs_xattr_set_acl,
};
static const struct afs_operation_ops yfs_fetch_opaque_acl_operation = {
.issue_yfs_rpc = yfs_fs_fetch_opaque_acl,
.success = afs_acl_success,
/* Don't free op->yacl in .put here */
};
/*
* Get a file's YFS ACL.
*/
static int afs_xattr_get_yfs(const struct xattr_handler *handler,
struct dentry *dentry,
struct inode *inode, const char *name,
void *buffer, size_t size)
{
struct afs_operation *op;
struct afs_vnode *vnode = AFS_FS_I(inode);
struct yfs_acl *yacl = NULL;
char buf[16], *data;
int which = 0, dsize, ret = -ENOMEM;
if (strcmp(name, "acl") == 0)
which = 0;
else if (strcmp(name, "acl_inherited") == 0)
which = 1;
else if (strcmp(name, "acl_num_cleaned") == 0)
which = 2;
else if (strcmp(name, "vol_acl") == 0)
which = 3;
else
return -EOPNOTSUPP;
yacl = kzalloc(sizeof(struct yfs_acl), GFP_KERNEL);
if (!yacl)
goto error;
if (which == 0)
yacl->flags |= YFS_ACL_WANT_ACL;
else if (which == 3)
yacl->flags |= YFS_ACL_WANT_VOL_ACL;
op = afs_alloc_operation(NULL, vnode->volume);
if (IS_ERR(op))
goto error_yacl;
afs_op_set_vnode(op, 0, vnode);
op->yacl = yacl;
op->ops = &yfs_fetch_opaque_acl_operation;
afs_begin_vnode_operation(op);
afs_wait_for_operation(op);
ret = afs_put_operation(op);
if (ret == 0) {
switch (which) {
case 0:
data = yacl->acl->data;
dsize = yacl->acl->size;
break;
case 1:
data = buf;
dsize = scnprintf(buf, sizeof(buf), "%u", yacl->inherit_flag);
break;
case 2:
data = buf;
dsize = scnprintf(buf, sizeof(buf), "%u", yacl->num_cleaned);
break;
case 3:
data = yacl->vol_acl->data;
dsize = yacl->vol_acl->size;
break;
default:
ret = -EOPNOTSUPP;
goto error_yacl;
}
ret = dsize;
if (size > 0) {
if (dsize <= size)
memcpy(buffer, data, dsize);
else
ret = -ERANGE;
}
} else if (ret == -ENOTSUPP) {
ret = -ENODATA;
}
error_yacl:
yfs_free_opaque_acl(yacl);
error:
return ret;
}
static const struct afs_operation_ops yfs_store_opaque_acl2_operation = {
.issue_yfs_rpc = yfs_fs_store_opaque_acl2,
.success = afs_acl_success,
.put = afs_acl_put,
};
/*
* Set a file's YFS ACL.
*/
static int afs_xattr_set_yfs(const struct xattr_handler *handler,
struct user_namespace *mnt_userns,
struct dentry *dentry,
struct inode *inode, const char *name,
const void *buffer, size_t size, int flags)
{
struct afs_operation *op;
struct afs_vnode *vnode = AFS_FS_I(inode);
int ret;
if (flags == XATTR_CREATE ||
strcmp(name, "acl") != 0)
return -EINVAL;
op = afs_alloc_operation(NULL, vnode->volume);
if (IS_ERR(op))
return -ENOMEM;
afs_op_set_vnode(op, 0, vnode);
if (!afs_make_acl(op, buffer, size))
return afs_put_operation(op);
op->ops = &yfs_store_opaque_acl2_operation;
ret = afs_do_sync_operation(op);
if (ret == -ENOTSUPP)
ret = -ENODATA;
return ret;
}
static const struct xattr_handler afs_xattr_yfs_handler = {
.prefix = "afs.yfs.",
.get = afs_xattr_get_yfs,
.set = afs_xattr_set_yfs,
};
/*
* Get the name of the cell on which a file resides.
*/
static int afs_xattr_get_cell(const struct xattr_handler *handler,
struct dentry *dentry,
struct inode *inode, const char *name,
void *buffer, size_t size)
{
struct afs_vnode *vnode = AFS_FS_I(inode);
struct afs_cell *cell = vnode->volume->cell;
size_t namelen;
namelen = cell->name_len;
if (size == 0)
return namelen;
if (namelen > size)
return -ERANGE;
memcpy(buffer, cell->name, namelen);
return namelen;
}
static const struct xattr_handler afs_xattr_afs_cell_handler = {
.name = "afs.cell",
.get = afs_xattr_get_cell,
};
/*
* Get the volume ID, vnode ID and vnode uniquifier of a file as a sequence of
* hex numbers separated by colons.
*/
static int afs_xattr_get_fid(const struct xattr_handler *handler,
struct dentry *dentry,
struct inode *inode, const char *name,
void *buffer, size_t size)
{
struct afs_vnode *vnode = AFS_FS_I(inode);
char text[16 + 1 + 24 + 1 + 8 + 1];
size_t len;
/* The volume ID is 64-bit, the vnode ID is 96-bit and the
* uniquifier is 32-bit.
*/
len = scnprintf(text, sizeof(text), "%llx:", vnode->fid.vid);
if (vnode->fid.vnode_hi)
len += scnprintf(text + len, sizeof(text) - len, "%x%016llx",
vnode->fid.vnode_hi, vnode->fid.vnode);
else
len += scnprintf(text + len, sizeof(text) - len, "%llx",
vnode->fid.vnode);
len += scnprintf(text + len, sizeof(text) - len, ":%x",
vnode->fid.unique);
if (size == 0)
return len;
if (len > size)
return -ERANGE;
memcpy(buffer, text, len);
return len;
}
static const struct xattr_handler afs_xattr_afs_fid_handler = {
.name = "afs.fid",
.get = afs_xattr_get_fid,
};
/*
* Get the name of the volume on which a file resides.
*/
static int afs_xattr_get_volume(const struct xattr_handler *handler,
struct dentry *dentry,
struct inode *inode, const char *name,
void *buffer, size_t size)
{
struct afs_vnode *vnode = AFS_FS_I(inode);
const char *volname = vnode->volume->name;
size_t namelen;
namelen = strlen(volname);
if (size == 0)
return namelen;
if (namelen > size)
return -ERANGE;
memcpy(buffer, volname, namelen);
return namelen;
}
static const struct xattr_handler afs_xattr_afs_volume_handler = {
.name = "afs.volume",
.get = afs_xattr_get_volume,
};
const struct xattr_handler *afs_xattr_handlers[] = {
&afs_xattr_afs_acl_handler,
&afs_xattr_afs_cell_handler,
&afs_xattr_afs_fid_handler,
&afs_xattr_afs_volume_handler,
&afs_xattr_yfs_handler, /* afs.yfs. prefix */
NULL
};