From: Frederick Lawler fred@cloudflare.com
[ 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 --- security/integrity/ima/ima_main.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index f3e7ac513db3f..f99ab1a3b0f09 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -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;