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![Dave Wysochanski](/assets/img/avatar_default.png)
Use the actual length of volume coherency data when setting the
xattr to avoid the following KASAN report.
BUG: KASAN: slab-out-of-bounds in cachefiles_set_volume_xattr+0xa0/0x350 [cachefiles]
Write of size 4 at addr ffff888101e02af4 by task kworker/6:0/1347
CPU: 6 PID: 1347 Comm: kworker/6:0 Kdump: loaded Not tainted 5.18.0-rc1-nfs-fscache-netfs+ #13
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-4.fc34 04/01/2014
Workqueue: events fscache_create_volume_work [fscache]
Call Trace:
<TASK>
dump_stack_lvl+0x45/0x5a
print_report.cold+0x5e/0x5db
? __lock_text_start+0x8/0x8
? cachefiles_set_volume_xattr+0xa0/0x350 [cachefiles]
kasan_report+0xab/0x120
? cachefiles_set_volume_xattr+0xa0/0x350 [cachefiles]
kasan_check_range+0xf5/0x1d0
memcpy+0x39/0x60
cachefiles_set_volume_xattr+0xa0/0x350 [cachefiles]
cachefiles_acquire_volume+0x2be/0x500 [cachefiles]
? __cachefiles_free_volume+0x90/0x90 [cachefiles]
fscache_create_volume_work+0x68/0x160 [fscache]
process_one_work+0x3b7/0x6a0
worker_thread+0x2c4/0x650
? process_one_work+0x6a0/0x6a0
kthread+0x16c/0x1a0
? kthread_complete_and_exit+0x20/0x20
ret_from_fork+0x22/0x30
</TASK>
Allocated by task 1347:
kasan_save_stack+0x1e/0x40
__kasan_kmalloc+0x81/0xa0
cachefiles_set_volume_xattr+0x76/0x350 [cachefiles]
cachefiles_acquire_volume+0x2be/0x500 [cachefiles]
fscache_create_volume_work+0x68/0x160 [fscache]
process_one_work+0x3b7/0x6a0
worker_thread+0x2c4/0x650
kthread+0x16c/0x1a0
ret_from_fork+0x22/0x30
The buggy address belongs to the object at ffff888101e02af0
which belongs to the cache kmalloc-8 of size 8
The buggy address is located 4 bytes inside of
8-byte region [ffff888101e02af0, ffff888101e02af8)
The buggy address belongs to the physical page:
page:00000000a2292d70 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x101e02
flags: 0x17ffffc0000200(slab|node=0|zone=2|lastcpupid=0x1fffff)
raw: 0017ffffc0000200 0000000000000000 dead000000000001 ffff888100042280
raw: 0000000000000000 0000000080660066 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
Memory state around the buggy address:
ffff888101e02980: fc 00 fc fc fc fc 00 fc fc fc fc 00 fc fc fc fc
ffff888101e02a00: 00 fc fc fc fc 00 fc fc fc fc 00 fc fc fc fc 00
>ffff888101e02a80: fc fc fc fc 00 fc fc fc fc 00 fc fc fc fc 04 fc
^
ffff888101e02b00: fc fc fc 00 fc fc fc fc 00 fc fc fc fc 00 fc fc
ffff888101e02b80: fc fc 00 fc fc fc fc 00 fc fc fc fc 00 fc fc fc
==================================================================
Fixes: 413a4a6b0b
"cachefiles: Fix volume coherency attribute"
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: linux-cachefs@redhat.com
Link: https://lore.kernel.org/r/20220405134649.6579-1-dwysocha@redhat.com/ # v1
Link: https://lore.kernel.org/r/20220405142810.8208-1-dwysocha@redhat.com/ # Incorrect v2
276 lines
7.7 KiB
C
276 lines
7.7 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/* CacheFiles extended attribute management
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*
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* Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*/
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#include <linux/module.h>
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#include <linux/sched.h>
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#include <linux/file.h>
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#include <linux/fs.h>
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#include <linux/fsnotify.h>
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#include <linux/quotaops.h>
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#include <linux/xattr.h>
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#include <linux/slab.h>
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#include "internal.h"
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#define CACHEFILES_COOKIE_TYPE_DATA 1
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struct cachefiles_xattr {
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__be64 object_size; /* Actual size of the object */
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__be64 zero_point; /* Size after which server has no data not written by us */
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__u8 type; /* Type of object */
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__u8 content; /* Content presence (enum cachefiles_content) */
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__u8 data[]; /* netfs coherency data */
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} __packed;
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static const char cachefiles_xattr_cache[] =
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XATTR_USER_PREFIX "CacheFiles.cache";
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struct cachefiles_vol_xattr {
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__be32 reserved; /* Reserved, should be 0 */
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__u8 data[]; /* netfs volume coherency data */
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} __packed;
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/*
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* set the state xattr on a cache file
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*/
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int cachefiles_set_object_xattr(struct cachefiles_object *object)
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{
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struct cachefiles_xattr *buf;
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struct dentry *dentry;
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struct file *file = object->file;
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unsigned int len = object->cookie->aux_len;
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int ret;
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if (!file)
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return -ESTALE;
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dentry = file->f_path.dentry;
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_enter("%x,#%d", object->debug_id, len);
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buf = kmalloc(sizeof(struct cachefiles_xattr) + len, GFP_KERNEL);
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if (!buf)
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return -ENOMEM;
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buf->object_size = cpu_to_be64(object->cookie->object_size);
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buf->zero_point = 0;
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buf->type = CACHEFILES_COOKIE_TYPE_DATA;
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buf->content = object->content_info;
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if (test_bit(FSCACHE_COOKIE_LOCAL_WRITE, &object->cookie->flags))
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buf->content = CACHEFILES_CONTENT_DIRTY;
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if (len > 0)
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memcpy(buf->data, fscache_get_aux(object->cookie), len);
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ret = cachefiles_inject_write_error();
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if (ret == 0)
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ret = vfs_setxattr(&init_user_ns, dentry, cachefiles_xattr_cache,
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buf, sizeof(struct cachefiles_xattr) + len, 0);
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if (ret < 0) {
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trace_cachefiles_vfs_error(object, file_inode(file), ret,
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cachefiles_trace_setxattr_error);
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trace_cachefiles_coherency(object, file_inode(file)->i_ino,
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buf->content,
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cachefiles_coherency_set_fail);
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if (ret != -ENOMEM)
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cachefiles_io_error_obj(
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object,
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"Failed to set xattr with error %d", ret);
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} else {
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trace_cachefiles_coherency(object, file_inode(file)->i_ino,
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buf->content,
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cachefiles_coherency_set_ok);
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}
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kfree(buf);
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_leave(" = %d", ret);
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return ret;
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}
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/*
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* check the consistency between the backing cache and the FS-Cache cookie
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*/
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int cachefiles_check_auxdata(struct cachefiles_object *object, struct file *file)
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{
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struct cachefiles_xattr *buf;
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struct dentry *dentry = file->f_path.dentry;
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unsigned int len = object->cookie->aux_len, tlen;
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const void *p = fscache_get_aux(object->cookie);
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enum cachefiles_coherency_trace why;
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ssize_t xlen;
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int ret = -ESTALE;
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tlen = sizeof(struct cachefiles_xattr) + len;
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buf = kmalloc(tlen, GFP_KERNEL);
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if (!buf)
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return -ENOMEM;
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xlen = cachefiles_inject_read_error();
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if (xlen == 0)
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xlen = vfs_getxattr(&init_user_ns, dentry, cachefiles_xattr_cache, buf, tlen);
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if (xlen != tlen) {
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if (xlen < 0)
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trace_cachefiles_vfs_error(object, file_inode(file), xlen,
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cachefiles_trace_getxattr_error);
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if (xlen == -EIO)
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cachefiles_io_error_obj(
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object,
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"Failed to read aux with error %zd", xlen);
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why = cachefiles_coherency_check_xattr;
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} else if (buf->type != CACHEFILES_COOKIE_TYPE_DATA) {
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why = cachefiles_coherency_check_type;
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} else if (memcmp(buf->data, p, len) != 0) {
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why = cachefiles_coherency_check_aux;
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} else if (be64_to_cpu(buf->object_size) != object->cookie->object_size) {
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why = cachefiles_coherency_check_objsize;
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} else if (buf->content == CACHEFILES_CONTENT_DIRTY) {
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// TODO: Begin conflict resolution
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pr_warn("Dirty object in cache\n");
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why = cachefiles_coherency_check_dirty;
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} else {
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why = cachefiles_coherency_check_ok;
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ret = 0;
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}
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trace_cachefiles_coherency(object, file_inode(file)->i_ino,
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buf->content, why);
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kfree(buf);
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return ret;
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}
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/*
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* remove the object's xattr to mark it stale
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*/
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int cachefiles_remove_object_xattr(struct cachefiles_cache *cache,
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struct cachefiles_object *object,
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struct dentry *dentry)
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{
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int ret;
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ret = cachefiles_inject_remove_error();
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if (ret == 0)
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ret = vfs_removexattr(&init_user_ns, dentry, cachefiles_xattr_cache);
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if (ret < 0) {
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trace_cachefiles_vfs_error(object, d_inode(dentry), ret,
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cachefiles_trace_remxattr_error);
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if (ret == -ENOENT || ret == -ENODATA)
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ret = 0;
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else if (ret != -ENOMEM)
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cachefiles_io_error(cache,
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"Can't remove xattr from %lu"
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" (error %d)",
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d_backing_inode(dentry)->i_ino, -ret);
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}
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_leave(" = %d", ret);
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return ret;
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}
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/*
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* Stick a marker on the cache object to indicate that it's dirty.
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*/
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void cachefiles_prepare_to_write(struct fscache_cookie *cookie)
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{
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const struct cred *saved_cred;
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struct cachefiles_object *object = cookie->cache_priv;
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struct cachefiles_cache *cache = object->volume->cache;
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_enter("c=%08x", object->cookie->debug_id);
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if (!test_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags)) {
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cachefiles_begin_secure(cache, &saved_cred);
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cachefiles_set_object_xattr(object);
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cachefiles_end_secure(cache, saved_cred);
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}
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}
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/*
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* Set the state xattr on a volume directory.
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*/
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bool cachefiles_set_volume_xattr(struct cachefiles_volume *volume)
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{
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struct cachefiles_vol_xattr *buf;
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unsigned int len = volume->vcookie->coherency_len;
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const void *p = volume->vcookie->coherency;
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struct dentry *dentry = volume->dentry;
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int ret;
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_enter("%x,#%d", volume->vcookie->debug_id, len);
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len += sizeof(*buf);
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buf = kmalloc(len, GFP_KERNEL);
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if (!buf)
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return false;
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buf->reserved = cpu_to_be32(0);
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memcpy(buf->data, p, volume->vcookie->coherency_len);
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ret = cachefiles_inject_write_error();
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if (ret == 0)
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ret = vfs_setxattr(&init_user_ns, dentry, cachefiles_xattr_cache,
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buf, len, 0);
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if (ret < 0) {
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trace_cachefiles_vfs_error(NULL, d_inode(dentry), ret,
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cachefiles_trace_setxattr_error);
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trace_cachefiles_vol_coherency(volume, d_inode(dentry)->i_ino,
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cachefiles_coherency_vol_set_fail);
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if (ret != -ENOMEM)
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cachefiles_io_error(
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volume->cache, "Failed to set xattr with error %d", ret);
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} else {
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trace_cachefiles_vol_coherency(volume, d_inode(dentry)->i_ino,
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cachefiles_coherency_vol_set_ok);
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}
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kfree(buf);
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_leave(" = %d", ret);
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return ret == 0;
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}
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/*
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* Check the consistency between the backing cache and the volume cookie.
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*/
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int cachefiles_check_volume_xattr(struct cachefiles_volume *volume)
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{
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struct cachefiles_vol_xattr *buf;
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struct dentry *dentry = volume->dentry;
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unsigned int len = volume->vcookie->coherency_len;
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const void *p = volume->vcookie->coherency;
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enum cachefiles_coherency_trace why;
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ssize_t xlen;
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int ret = -ESTALE;
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_enter("");
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len += sizeof(*buf);
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buf = kmalloc(len, GFP_KERNEL);
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if (!buf)
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return -ENOMEM;
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xlen = cachefiles_inject_read_error();
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if (xlen == 0)
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xlen = vfs_getxattr(&init_user_ns, dentry, cachefiles_xattr_cache, buf, len);
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if (xlen != len) {
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if (xlen < 0) {
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trace_cachefiles_vfs_error(NULL, d_inode(dentry), xlen,
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cachefiles_trace_getxattr_error);
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if (xlen == -EIO)
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cachefiles_io_error(
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volume->cache,
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"Failed to read xattr with error %zd", xlen);
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}
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why = cachefiles_coherency_vol_check_xattr;
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} else if (buf->reserved != cpu_to_be32(0)) {
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why = cachefiles_coherency_vol_check_resv;
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} else if (memcmp(buf->data, p, len - sizeof(*buf)) != 0) {
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why = cachefiles_coherency_vol_check_cmp;
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} else {
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why = cachefiles_coherency_vol_check_ok;
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ret = 0;
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}
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trace_cachefiles_vol_coherency(volume, d_inode(dentry)->i_ino, why);
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kfree(buf);
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_leave(" = %d", ret);
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return ret;
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}
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