ima: process_measurement() needlessly takes inode_lock() on MAY_READ

[ Upstream commit 30d68cb0c37ebe2dc63aa1d46a28b9163e61caa2 ]

On IMA policy update, if a measure rule exists in the policy,
IMA_MEASURE is set for ima_policy_flags which makes the violation_check
variable always true. Coupled with a no-action on MAY_READ for a
FILE_CHECK call, we're always taking the inode_lock().

This becomes a performance problem for extremely heavy read-only workloads.
Therefore, prevent this only in the case there's no action to be taken.

Signed-off-by: Frederick Lawler <fred@cloudflare.com>
Acked-by: Roberto Sassu <roberto.sassu@huawei.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Frederick Lawler
2025-03-27 11:09:11 -05:00
committed by Greg Kroah-Hartman
parent 91ba964a75
commit 722a6972de

View File

@@ -235,7 +235,9 @@ static int process_measurement(struct file *file, const struct cred *cred,
&allowed_algos);
violation_check = ((func == FILE_CHECK || func == MMAP_CHECK ||
func == MMAP_CHECK_REQPROT) &&
(ima_policy_flag & IMA_MEASURE));
(ima_policy_flag & IMA_MEASURE) &&
((action & IMA_MEASURE) ||
(file->f_mode & FMODE_WRITE)));
if (!action && !violation_check)
return 0;