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authorMimi Zohar <zohar@linux.ibm.com>2023-10-18 21:47:02 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2023-11-28 20:07:12 +0300
commit143f450c6cb28890da0002ebd1764cc804258de1 (patch)
tree7840918d761aab1ea7f7caac8a9f6bd727ae80df /security
parent2c63b9d7f7c8558fdfdd4bdb77c04f1cf8eab221 (diff)
downloadlinux-143f450c6cb28890da0002ebd1764cc804258de1.tar.xz
ima: detect changes to the backing overlay file
commit b836c4d29f2744200b2af41e14bf50758dddc818 upstream. Commit 18b44bc5a672 ("ovl: Always reevaluate the file signature for IMA") forced signature re-evaulation on every file access. Instead of always re-evaluating the file's integrity, detect a change to the backing file, by comparing the cached file metadata with the backing file's metadata. Verifying just the i_version has not changed is insufficient. In addition save and compare the i_ino and s_dev as well. Reviewed-by: Amir Goldstein <amir73il@gmail.com> Tested-by: Eric Snowberg <eric.snowberg@oracle.com> Tested-by: Raul E Rangel <rrangel@chromium.org> Cc: stable@vger.kernel.org Signed-off-by: Mimi Zohar <zohar@linux.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'security')
-rw-r--r--security/integrity/ima/ima_api.c5
-rw-r--r--security/integrity/ima/ima_main.c16
-rw-r--r--security/integrity/integrity.h2
3 files changed, 22 insertions, 1 deletions
diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
index 1e3a7a4f8833..026c8c9db992 100644
--- a/security/integrity/ima/ima_api.c
+++ b/security/integrity/ima/ima_api.c
@@ -243,6 +243,7 @@ int ima_collect_measurement(struct integrity_iint_cache *iint,
{
const char *audit_cause = "failed";
struct inode *inode = file_inode(file);
+ struct inode *real_inode = d_real_inode(file_dentry(file));
const char *filename = file->f_path.dentry->d_name.name;
struct ima_max_digest_data hash;
int result = 0;
@@ -305,6 +306,10 @@ int ima_collect_measurement(struct integrity_iint_cache *iint,
iint->ima_hash = tmpbuf;
memcpy(iint->ima_hash, &hash, length);
iint->version = i_version;
+ if (real_inode != inode) {
+ iint->real_ino = real_inode->i_ino;
+ iint->real_dev = real_inode->i_sb->s_dev;
+ }
/* Possibly temporary failure due to type of read (eg. O_DIRECT) */
if (!result)
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index bc84a0ac25aa..185666d90eeb 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -26,6 +26,7 @@
#include <linux/ima.h>
#include <linux/iversion.h>
#include <linux/fs.h>
+#include <linux/iversion.h>
#include "ima.h"
@@ -202,7 +203,7 @@ static int process_measurement(struct file *file, const struct cred *cred,
u32 secid, char *buf, loff_t size, int mask,
enum ima_hooks func)
{
- struct inode *inode = file_inode(file);
+ struct inode *backing_inode, *inode = file_inode(file);
struct integrity_iint_cache *iint = NULL;
struct ima_template_desc *template_desc = NULL;
char *pathbuf = NULL;
@@ -278,6 +279,19 @@ static int process_measurement(struct file *file, const struct cred *cred,
iint->measured_pcrs = 0;
}
+ /* Detect and re-evaluate changes made to the backing file. */
+ backing_inode = d_real_inode(file_dentry(file));
+ if (backing_inode != inode &&
+ (action & IMA_DO_MASK) && (iint->flags & IMA_DONE_MASK)) {
+ if (!IS_I_VERSION(backing_inode) ||
+ backing_inode->i_sb->s_dev != iint->real_dev ||
+ backing_inode->i_ino != iint->real_ino ||
+ !inode_eq_iversion(backing_inode, iint->version)) {
+ iint->flags &= ~IMA_DONE_MASK;
+ iint->measured_pcrs = 0;
+ }
+ }
+
/* Determine if already appraised/measured based on bitmask
* (IMA_MEASURE, IMA_MEASURED, IMA_XXXX_APPRAISE, IMA_XXXX_APPRAISED,
* IMA_AUDIT, IMA_AUDITED)
diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h
index 7167a6e99bdc..52c3c806bf69 100644
--- a/security/integrity/integrity.h
+++ b/security/integrity/integrity.h
@@ -164,6 +164,8 @@ struct integrity_iint_cache {
unsigned long flags;
unsigned long measured_pcrs;
unsigned long atomic_flags;
+ unsigned long real_ino;
+ dev_t real_dev;
enum integrity_status ima_file_status:4;
enum integrity_status ima_mmap_status:4;
enum integrity_status ima_bprm_status:4;