[RFC,v2,1/2] ima: limit the number of open-writers integrity violations

Commit Message

Mimi Zohar Feb. 5, 2025, 3:32 a.m. UTC

Limit the number of open-writers integrity violation audit messages
and records in the IMA measurement list emitted when re-opening a
file for read.

Signed-off-by: Mimi Zohar <[e-mail]>
---
 security/integrity/ima/ima.h      |  1 +
 security/integrity/ima/ima_main.c | 14 ++++++++++++--
 2 files changed, 13 insertions(+), 2 deletions(-)

Patch

diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index a4f284bd846c..7f21568544dd 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -182,6 +182,7 @@  struct ima_kexec_hdr {
 #define IMA_CHANGE_ATTR		2
 #define IMA_DIGSIG		3
 #define IMA_MUST_MEASURE	4
+#define IMA_LIMIT_VIOLATIONS	5
 
 /* IMA integrity metadata associated with an inode */
 struct ima_iint_cache {
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 28b8b0db6f9b..5091ad931677 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -137,8 +137,16 @@  static void ima_rdwr_violation_check(struct file *file,
 	} else {
 		if (must_measure)
 			set_bit(IMA_MUST_MEASURE, &iint->atomic_flags);
-		if (inode_is_open_for_write(inode) && must_measure)
-			send_writers = true;
+
+		if (inode_is_open_for_write(inode) && must_measure) {
+			if (!iint)
+				iint = ima_iint_find(inode);
+
+			/* Limit number of open_writers violations */
+			if (iint && !test_and_set_bit(IMA_LIMIT_VIOLATIONS,
+						      &iint->atomic_flags))
+				send_writers = true;
+		}
 	}
 
 	if (!send_tomtou && !send_writers)
@@ -167,6 +175,8 @@  static void ima_check_last_writer(struct ima_iint_cache *iint,
 	if (atomic_read(&inode->i_writecount) == 1) {
 		struct kstat stat;
 
+		clear_bit(IMA_LIMIT_VIOLATIONS, &iint->atomic_flags);
+
 		update = test_and_clear_bit(IMA_UPDATE_XATTR,
 					    &iint->atomic_flags);
 		if ((iint->flags & IMA_NEW_FILE) ||