| Message ID | 20250327160916.279090-1-fred@cloudflare.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v3] ima: process_measurement() needlessly takes inode_lock() on MAY_READ | expand |
On Thu, 2025-03-27 at 11:09 -0500, Frederick Lawler wrote: > 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> Thanks Frederick! Acked-by: Roberto Sassu <roberto.sassu@huawei.com> Roberto > --- > Changes since v2: > - s/mask & MAY_WRITE/file->f_mode & FMODE_WRITE/ > > Changes since v1: > - Add MAY_WRITE && action check to violation_check to avoid MAY_READ > only situations > --- > 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 9b87556b03a7..bc453f5a7531 100644 > --- a/security/integrity/ima/ima_main.c > +++ b/security/integrity/ima/ima_main.c > @@ -237,7 +237,9 @@ 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; >
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index 9b87556b03a7..bc453f5a7531 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -237,7 +237,9 @@ 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;
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 v2: - s/mask & MAY_WRITE/file->f_mode & FMODE_WRITE/ Changes since v1: - Add MAY_WRITE && action check to violation_check to avoid MAY_READ only situations --- security/integrity/ima/ima_main.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)