FAILED: patch "[PATCH] ima: limit the number of ToMToU integrity violations" failed to apply to 6.6-stable tree

The patch below does not apply to the 6.6-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x a414016218ca97140171aa3bb926b02e1f68c2cc
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2025041739-props-huff-8deb@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From a414016218ca97140171aa3bb926b02e1f68c2cc Mon Sep 17 00:00:00 2001
From: Mimi Zohar <[email protected]>
Date: Mon, 27 Jan 2025 10:45:48 -0500
Subject: [PATCH] ima: limit the number of ToMToU integrity violations

Each time a file in policy, that is already opened for read, is opened for write, a Time-of-Measure-Time-of-Use (ToMToU) integrity violation audit message is emitted and a violation record is added to the IMA measurement list. This occurs even if a ToMToU violation has already been recorded.

Limit the number of ToMToU integrity violations per file open for read.

Note: The IMA_MAY_EMIT_TOMTOU atomic flag must be set from the reader side based on policy. This may result in a per file open for read ToMToU violation.

Since IMA_MUST_MEASURE is only used for violations, rename the atomic IMA_MUST_MEASURE flag to IMA_MAY_EMIT_TOMTOU.

index 3423b3088de5..e0489c6f7f59 100644
@@ -181,7 +181,7 @@ struct ima_kexec_hdr {
 #define IMA_UPDATE_XATTR	1
 #define IMA_CHANGE_ATTR		2
 #define IMA_DIGSIG		3
-#define IMA_MUST_MEASURE	4
+#define IMA_MAY_EMIT_TOMTOU	4
 #define IMA_EMITTED_OPENWRITERS	5
 
 /* IMA integrity metadata associated with an inode */

index 95118c1887cb..f3e7ac513db3 100644
@@ -129,14 +129,15 @@ static void ima_rdwr_violation_check(struct file *file,
 		if (atomic_read(&inode->i_readcount) && IS_IMA(inode)) {
 			if (!iint)
 				iint = ima_iint_find(inode);
+
 			/* IMA_MEASURE is set from reader side */
-			if (iint && test_bit(IMA_MUST_MEASURE,
-						&iint->atomic_flags))
+			if (iint && test_and_clear_bit(IMA_MAY_EMIT_TOMTOU,
+						       &iint->atomic_flags))
 				send_tomtou = true;
 		}
 	} else {
 		if (must_measure)
-			set_bit(IMA_MUST_MEASURE, &iint->atomic_flags);
+			set_bit(IMA_MAY_EMIT_TOMTOU, &iint->atomic_flags);
 
 		/* Limit number of open_writers violations */
 		if (inode_is_open_for_write(inode) && must_measure) {

From: Mimi Zohar <[email protected]>

[ Upstream commit a414016218ca97140171aa3bb926b02e1f68c2cc ]

Each time a file in policy, that is already opened for read, is opened for write, a Time-of-Measure-Time-of-Use (ToMToU) integrity violation audit message is emitted and a violation record is added to the IMA measurement list. This occurs even if a ToMToU violation has already been recorded.

Limit the number of ToMToU integrity violations per file open for read.

Note: The IMA_MAY_EMIT_TOMTOU atomic flag must be set from the reader side based on policy. This may result in a per file open for read ToMToU violation.

Since IMA_MUST_MEASURE is only used for violations, rename the atomic IMA_MUST_MEASURE flag to IMA_MAY_EMIT_TOMTOU.

---
 security/integrity/ima/ima_main.c | 16 +++++++++++-----
 security/integrity/integrity.h    |  3 ++-
 2 files changed, 13 insertions(+), 6 deletions(-)

index 068edb0d79f73..3b734a4dfcbe4 100644
@@ -128,16 +128,22 @@ static void ima_rdwr_violation_check(struct file *file,
 		if (atomic_read(&inode->i_readcount) && IS_IMA(inode)) {
 			if (!iint)
 				iint = integrity_iint_find(inode);
+
 			/* IMA_MEASURE is set from reader side */
-			if (iint && test_bit(IMA_MUST_MEASURE,
-						&iint->atomic_flags))
+			if (iint && test_and_clear_bit(IMA_MAY_EMIT_TOMTOU,
+						       &iint->atomic_flags))
 				send_tomtou = true;
 		}
 	} else {
 		if (must_measure)
-			set_bit(IMA_MUST_MEASURE, &iint->atomic_flags);
-		if (inode_is_open_for_write(inode) && must_measure)
-			send_writers = true;
+			set_bit(IMA_MAY_EMIT_TOMTOU, &iint->atomic_flags);
+
+		/* Limit number of open_writers violations */
+		if (inode_is_open_for_write(inode) && must_measure) {
+			if (!test_and_set_bit(IMA_EMITTED_OPENWRITERS,
+					      &iint->atomic_flags))
+				send_writers = true;
+		}
 	}
 
 	if (!send_tomtou && !send_writers)

index ad20ff7f5dfaa..a007edae938ae 100644
@@ -74,7 +74,8 @@
 #define IMA_UPDATE_XATTR	1
 #define IMA_CHANGE_ATTR		2
 #define IMA_DIGSIG		3
-#define IMA_MUST_MEASURE	4
+#define IMA_MAY_EMIT_TOMTOU	4
+#define IMA_EMITTED_OPENWRITERS	5
 
 enum evm_ima_xattr_type {
 	IMA_XATTR_DIGEST = 0x01,

2.51.0