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

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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>
This commit is contained in:
Frederick Lawler 2025-03-27 11:09:11 -05:00 committed by Roberto Sassu
parent 9c32cda43e
commit 30d68cb0c3
1 changed files with 3 additions and 1 deletions
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4
security/integrity/ima/ima_main.c
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@ -245,7 +245,9 @@ 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;