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ima: fallback to using i_version to detect file change

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Commit db1d1e8b98 ("IMA: use vfs_getattr_nosec to get the i_version")
replaced detecting file change based on i_version with
STATX_CHANGE_COOKIE.

On filesystems without STATX_CHANGE_COOKIE enabled, revert back to
detecting file change based on i_version.

On filesystems which do not support either, assume the file changed.

Reported-by: Frederick Lawler <fred@cloudflare.com>
Fixes: db1d1e8b98 ("IMA: use vfs_getattr_nosec to get the i_version")
Cc: stable@vger.kernel.org
Reviewed-by: Frederick Lawler <fred@cloudflare.com>
Tested-by: Frederick Lawler <fred@cloudflare.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
This commit is contained in:
Mimi Zohar
2026-02-02 11:23:47 -05:00
parent 0ec959cf4b
commit 01baa39cf5
2 changed files with 35 additions and 12 deletions
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13
security/integrity/ima/ima_api.c
View File

@@ -269,15 +269,20 @@ int ima_collect_measurement(struct ima_iint_cache *iint, struct file *file,
goto out;
/*
* Detecting file change is based on i_version. On filesystems
* which do not support i_version, support was originally limited
* to an initial measurement/appraisal/audit, but was modified to
* assume the file changed.
* Detect file change based on STATX_CHANGE_COOKIE, when supported,
* and fallback to detecting file change based on i_version.
*
* On filesystems which did not support i_version, support was
* originally limited to an initial measurement/appraisal/audit,
* but was later modified to assume the file changed.
*/
result = vfs_getattr_nosec(&file->f_path, &stat, STATX_CHANGE_COOKIE,
AT_STATX_SYNC_AS_STAT);
if (!result && (stat.result_mask & STATX_CHANGE_COOKIE))
i_version = stat.change_cookie;
else if (IS_I_VERSION(real_inode))
i_version = inode_peek_iversion(real_inode);
hash.hdr.algo = algo;
hash.hdr.length = hash_digest_size[algo];

34
security/integrity/ima/ima_main.c
View File

@@ -180,6 +180,29 @@ static void ima_rdwr_violation_check(struct file *file,
"invalid_pcr", "open_writers");
}
/*
* Detect file change based on STATX_CHANGE_COOKIE, when supported, and
* fallback to detecting file change based on i_version. On filesystems
* which do not support either, assume the file changed.
*/
static bool ima_detect_file_change(struct ima_iint_cache *iint,
struct inode *inode, struct file *file)
{
struct kstat stat;
int result;
result = vfs_getattr_nosec(&file->f_path, &stat, STATX_CHANGE_COOKIE,
AT_STATX_SYNC_AS_STAT);
if (!result && stat.result_mask & STATX_CHANGE_COOKIE)
return stat.change_cookie != iint->real_inode.version;
if (IS_I_VERSION(inode))
return !inode_eq_iversion(inode, iint->real_inode.version);
return true;
}
static void ima_check_last_writer(struct ima_iint_cache *iint,
struct inode *inode, struct file *file)
{
@@ -191,18 +214,13 @@ static void ima_check_last_writer(struct ima_iint_cache *iint,
mutex_lock(&iint->mutex);
if (atomic_read(&inode->i_writecount) == 1) {
struct kstat stat;
clear_bit(IMA_EMITTED_OPENWRITERS, &iint->atomic_flags);
update = test_and_clear_bit(IMA_UPDATE_XATTR,
&iint->atomic_flags);
if ((iint->flags & IMA_NEW_FILE) ||
vfs_getattr_nosec(&file->f_path, &stat,
STATX_CHANGE_COOKIE,
AT_STATX_SYNC_AS_STAT) ||
!(stat.result_mask & STATX_CHANGE_COOKIE) ||
stat.change_cookie != iint->real_inode.version) {
if (iint->flags & IMA_NEW_FILE ||
ima_detect_file_change(iint, inode, file)) {
iint->flags &= ~(IMA_DONE_MASK | IMA_NEW_FILE);
iint->measured_pcrs = 0;
if (update)