linux-stable/fs/afs/xattr.c
Mark Salyzyn 2e2fae99d1 afs: xattr: use scnprintf
sprintf and snprintf are fragile in future maintenance, switch to
using scnprintf to ensure no accidental Use After Free conditions
are introduced.

Signed-off-by: Mark Salyzyn <salyzyn@android.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org
Cc: David Howells <dhowells@redhat.com>
Cc: linux-afs@lists.infradead.org
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: David Howells <dhowells@redhat.com>
2019-11-21 09:12:17 +00:00

429 lines
9.7 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"
static const char afs_xattr_list[] =
"afs.acl\0"
"afs.cell\0"
"afs.fid\0"
"afs.volume\0"
"afs.yfs.acl\0"
"afs.yfs.acl_inherited\0"
"afs.yfs.acl_num_cleaned\0"
"afs.yfs.vol_acl";
/*
* Retrieve a list of the supported xattrs.
*/
ssize_t afs_listxattr(struct dentry *dentry, char *buffer, size_t size)
{
if (size == 0)
return sizeof(afs_xattr_list);
if (size < sizeof(afs_xattr_list))
return -ERANGE;
memcpy(buffer, afs_xattr_list, sizeof(afs_xattr_list));
return sizeof(afs_xattr_list);
}
/*
* 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_fs_cursor fc;
struct afs_status_cb *scb;
struct afs_vnode *vnode = AFS_FS_I(inode);
struct afs_acl *acl = NULL;
struct key *key;
int ret = -ENOMEM;
scb = kzalloc(sizeof(struct afs_status_cb), GFP_NOFS);
if (!scb)
goto error;
key = afs_request_key(vnode->volume->cell);
if (IS_ERR(key)) {
ret = PTR_ERR(key);
goto error_scb;
}
ret = -ERESTARTSYS;
if (afs_begin_vnode_operation(&fc, vnode, key, true)) {
afs_dataversion_t data_version = vnode->status.data_version;
while (afs_select_fileserver(&fc)) {
fc.cb_break = afs_calc_vnode_cb_break(vnode);
acl = afs_fs_fetch_acl(&fc, scb);
}
afs_check_for_remote_deletion(&fc, fc.vnode);
afs_vnode_commit_status(&fc, vnode, fc.cb_break,
&data_version, scb);
ret = afs_end_vnode_operation(&fc);
}
if (ret == 0) {
ret = acl->size;
if (size > 0) {
if (acl->size <= size)
memcpy(buffer, acl->data, acl->size);
else
ret = -ERANGE;
}
kfree(acl);
}
key_put(key);
error_scb:
kfree(scb);
error:
return ret;
}
/*
* Set a file's AFS3 ACL.
*/
static int afs_xattr_set_acl(const struct xattr_handler *handler,
struct dentry *dentry,
struct inode *inode, const char *name,
const void *buffer, size_t size, int flags)
{
struct afs_fs_cursor fc;
struct afs_status_cb *scb;
struct afs_vnode *vnode = AFS_FS_I(inode);
struct afs_acl *acl = NULL;
struct key *key;
int ret = -ENOMEM;
if (flags == XATTR_CREATE)
return -EINVAL;
scb = kzalloc(sizeof(struct afs_status_cb), GFP_NOFS);
if (!scb)
goto error;
acl = kmalloc(sizeof(*acl) + size, GFP_KERNEL);
if (!acl)
goto error_scb;
key = afs_request_key(vnode->volume->cell);
if (IS_ERR(key)) {
ret = PTR_ERR(key);
goto error_acl;
}
acl->size = size;
memcpy(acl->data, buffer, size);
ret = -ERESTARTSYS;
if (afs_begin_vnode_operation(&fc, vnode, key, true)) {
afs_dataversion_t data_version = vnode->status.data_version;
while (afs_select_fileserver(&fc)) {
fc.cb_break = afs_calc_vnode_cb_break(vnode);
afs_fs_store_acl(&fc, acl, scb);
}
afs_check_for_remote_deletion(&fc, fc.vnode);
afs_vnode_commit_status(&fc, vnode, fc.cb_break,
&data_version, scb);
ret = afs_end_vnode_operation(&fc);
}
key_put(key);
error_acl:
kfree(acl);
error_scb:
kfree(scb);
error:
return ret;
}
static const struct xattr_handler afs_xattr_afs_acl_handler = {
.name = "afs.acl",
.get = afs_xattr_get_acl,
.set = afs_xattr_set_acl,
};
/*
* 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_fs_cursor fc;
struct afs_status_cb *scb;
struct afs_vnode *vnode = AFS_FS_I(inode);
struct yfs_acl *yacl = NULL;
struct key *key;
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;
scb = kzalloc(sizeof(struct afs_status_cb), GFP_NOFS);
if (!scb)
goto error_yacl;
key = afs_request_key(vnode->volume->cell);
if (IS_ERR(key)) {
ret = PTR_ERR(key);
goto error_scb;
}
ret = -ERESTARTSYS;
if (afs_begin_vnode_operation(&fc, vnode, key, true)) {
afs_dataversion_t data_version = vnode->status.data_version;
while (afs_select_fileserver(&fc)) {
fc.cb_break = afs_calc_vnode_cb_break(vnode);
yfs_fs_fetch_opaque_acl(&fc, yacl, scb);
}
afs_check_for_remote_deletion(&fc, fc.vnode);
afs_vnode_commit_status(&fc, vnode, fc.cb_break,
&data_version, scb);
ret = afs_end_vnode_operation(&fc);
}
if (ret < 0)
goto error_key;
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_key;
}
ret = dsize;
if (size > 0) {
if (dsize > size) {
ret = -ERANGE;
goto error_key;
}
memcpy(buffer, data, dsize);
}
error_key:
key_put(key);
error_scb:
kfree(scb);
error_yacl:
yfs_free_opaque_acl(yacl);
error:
return ret;
}
/*
* Set a file's YFS ACL.
*/
static int afs_xattr_set_yfs(const struct xattr_handler *handler,
struct dentry *dentry,
struct inode *inode, const char *name,
const void *buffer, size_t size, int flags)
{
struct afs_fs_cursor fc;
struct afs_status_cb *scb;
struct afs_vnode *vnode = AFS_FS_I(inode);
struct afs_acl *acl = NULL;
struct key *key;
int ret = -ENOMEM;
if (flags == XATTR_CREATE ||
strcmp(name, "acl") != 0)
return -EINVAL;
scb = kzalloc(sizeof(struct afs_status_cb), GFP_NOFS);
if (!scb)
goto error;
acl = kmalloc(sizeof(*acl) + size, GFP_KERNEL);
if (!acl)
goto error_scb;
acl->size = size;
memcpy(acl->data, buffer, size);
key = afs_request_key(vnode->volume->cell);
if (IS_ERR(key)) {
ret = PTR_ERR(key);
goto error_acl;
}
ret = -ERESTARTSYS;
if (afs_begin_vnode_operation(&fc, vnode, key, true)) {
afs_dataversion_t data_version = vnode->status.data_version;
while (afs_select_fileserver(&fc)) {
fc.cb_break = afs_calc_vnode_cb_break(vnode);
yfs_fs_store_opaque_acl2(&fc, acl, scb);
}
afs_check_for_remote_deletion(&fc, fc.vnode);
afs_vnode_commit_status(&fc, vnode, fc.cb_break,
&data_version, scb);
ret = afs_end_vnode_operation(&fc);
}
error_acl:
kfree(acl);
key_put(key);
error_scb:
kfree(scb);
error:
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
};