| Message ID | 20250325181616.79540-2-fred@cloudflare.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | ima: process_measurement() needlessly takes inode_lock() on MAY_READ | expand |
My mistake, this is PATCH v2. I forgot to change the subject in git send-email. I can resend if that's needed.
On 3/25/2025 7:18 PM, Frederick Lawler wrote: > My mistake, this is PATCH v2. I forgot to change the subject in git > send-email. I can resend if that's needed. No problem. However, let's change: mask & MAY_WRITE with file->f_mode & FMODE_WRITE Thanks Roberto
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index 9b87556b03a7..11a91d9dae48 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -237,7 +237,8 @@ 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) || (mask & MAY_WRITE))); if (!action && !violation_check) return 0;
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> --- Changes since v1: - Add MAY_WRITE && action check to violation_check to avoid MAY_READ only situations --- security/integrity/ima/ima_main.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)