Patch "IMA: use vfs_getattr_nosec to get the i_version" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    IMA: use vfs_getattr_nosec to get the i_version

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     ima-use-vfs_getattr_nosec-to-get-the-i_version.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 353023c6542fa48ee9c2dcc5b9a4c7627d9ab187
Author: Jeff Layton <jlayton@xxxxxxxxxx>
Date:   Mon Apr 17 12:55:51 2023 -0400

    IMA: use vfs_getattr_nosec to get the i_version
    
    [ Upstream commit db1d1e8b9867aae5c3e61ad7859abfcc4a6fd6c7 ]
    
    IMA currently accesses the i_version out of the inode directly when it
    does a measurement. This is fine for most simple filesystems, but can be
    problematic with more complex setups (e.g. overlayfs).
    
    Make IMA instead call vfs_getattr_nosec to get this info. This allows
    the filesystem to determine whether and how to report the i_version, and
    should allow IMA to work properly with a broader class of filesystems in
    the future.
    
    Reported-and-Tested-by: Stefan Berger <stefanb@xxxxxxxxxxxxx>
    Reviewed-by: Christian Brauner <brauner@xxxxxxxxxx>
    Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
    Signed-off-by: Mimi Zohar <zohar@xxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
index 04b9e465463b6..f8e2a9e0c7e97 100644
--- a/security/integrity/ima/ima_api.c
+++ b/security/integrity/ima/ima_api.c
@@ -13,7 +13,6 @@
 #include <linux/fs.h>
 #include <linux/xattr.h>
 #include <linux/evm.h>
-#include <linux/iversion.h>
 
 #include "ima.h"
 
@@ -218,10 +217,11 @@ int ima_collect_measurement(struct integrity_iint_cache *iint,
 	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 kstat stat;
 	int result = 0;
 	int length;
 	void *tmpbuf;
-	u64 i_version;
+	u64 i_version = 0;
 	struct {
 		struct ima_digest_data hdr;
 		char digest[IMA_MAX_DIGEST_SIZE];
@@ -243,7 +243,10 @@ int ima_collect_measurement(struct integrity_iint_cache *iint,
 	 * which do not support i_version, support is limited to an initial
 	 * measurement/appraisal/audit.
 	 */
-	i_version = inode_query_iversion(inode);
+	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;
 	hash.hdr.algo = algo;
 
 	/* Initialize hash digest to 0's in case of failure */
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 7cd9df8499296..f64d86dfff36f 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -24,7 +24,6 @@
 #include <linux/slab.h>
 #include <linux/xattr.h>
 #include <linux/ima.h>
-#include <linux/iversion.h>
 #include <linux/fs.h>
 #include <linux/iversion.h>
 
@@ -164,11 +163,16 @@ static void ima_check_last_writer(struct integrity_iint_cache *iint,
 
 	mutex_lock(&iint->mutex);
 	if (atomic_read(&inode->i_writecount) == 1) {
+		struct kstat stat;
+
 		update = test_and_clear_bit(IMA_UPDATE_XATTR,
 					    &iint->atomic_flags);
-		if (!IS_I_VERSION(inode) ||
-		    !inode_eq_iversion(inode, iint->version) ||
-		    (iint->flags & IMA_NEW_FILE)) {
+		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->version) {
 			iint->flags &= ~(IMA_DONE_MASK | IMA_NEW_FILE);
 			iint->measured_pcrs = 0;
 			if (update)