aboutsummaryrefslogtreecommitdiffstats
path: root/security
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2012-03-22 17:01:41 -0700
committerGerrit Code Review <gerrit@cyanogenmod.org>2015-11-09 06:36:29 -0800
commitda5606533e0bebb408b7e6df68caea46d387598e (patch)
tree2bdc82e7745f10ac82446c4f4621345e23e0323f /security
parente186fbacd6b7663536b3fc3cdc91fcccb25404d0 (diff)
downloadkernel_samsung_smdk4412-da5606533e0bebb408b7e6df68caea46d387598e.zip
kernel_samsung_smdk4412-da5606533e0bebb408b7e6df68caea46d387598e.tar.gz
kernel_samsung_smdk4412-da5606533e0bebb408b7e6df68caea46d387598e.tar.bz2
security: optimize avc_audit() common path
avc_audit() did a lot of jumping around and had a big stack frame, all for the uncommon case. Split up the uncommon case (which we really can't make go fast anyway) into its own slow function, and mark the conditional branches appropriately for the common likely case. This causes avc_audit() to no longer show up as one of the hottest functions on the branch profiles (the new "perf -b" thing), and makes the cycle profiles look really nice and dense too. The whole audit path is still annoyingly very much one of the biggest costs of name lookup, so these things are worth optimizing for. I wish we could just tell people to turn it off, but realistically we do need it: we just need to make sure that the overhead of the necessary evil is as low as possible. Change-Id: I7bbbcefa10317233d4484b41adbbe8a9a031a177 Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'security')
-rw-r--r--security/selinux/avc.c70
1 files changed, 41 insertions, 29 deletions
diff --git a/security/selinux/avc.c b/security/selinux/avc.c
index d515b21..e759527 100644
--- a/security/selinux/avc.c
+++ b/security/selinux/avc.c
@@ -457,6 +457,42 @@ static void avc_audit_post_callback(struct audit_buffer *ab, void *a)
ad->selinux_audit_data.tclass);
}
+/* This is the slow part of avc audit with big stack footprint */
+static noinline int slow_avc_audit(u32 ssid, u32 tsid, u16 tclass,
+ u32 requested, u32 audited, u32 denied,
+ struct av_decision *avd, struct common_audit_data *a,
+ unsigned flags)
+{
+ struct common_audit_data stack_data;
+
+ if (!a) {
+ a = &stack_data;
+ COMMON_AUDIT_DATA_INIT(a, NONE);
+ }
+
+ /*
+ * When in a RCU walk do the audit on the RCU retry. This is because
+ * the collection of the dname in an inode audit message is not RCU
+ * safe. Note this may drop some audits when the situation changes
+ * during retry. However this is logically just as if the operation
+ * happened a little later.
+ */
+ if ((a->type == LSM_AUDIT_DATA_INODE) &&
+ (flags & IPERM_FLAG_RCU))
+ return -ECHILD;
+
+ a->selinux_audit_data.tclass = tclass;
+ a->selinux_audit_data.requested = requested;
+ a->selinux_audit_data.ssid = ssid;
+ a->selinux_audit_data.tsid = tsid;
+ a->selinux_audit_data.audited = audited;
+ a->selinux_audit_data.denied = denied;
+ a->lsm_pre_audit = avc_audit_pre_callback;
+ a->lsm_post_audit = avc_audit_post_callback;
+ common_lsm_audit(a);
+ return 0;
+}
+
/**
* avc_audit - Audit the granting or denial of permissions.
* @ssid: source security identifier
@@ -482,10 +518,9 @@ int avc_audit(u32 ssid, u32 tsid,
struct av_decision *avd, int result, struct common_audit_data *a,
unsigned flags)
{
- struct common_audit_data stack_data;
u32 denied, audited;
denied = requested & ~avd->allowed;
- if (denied) {
+ if (unlikely(denied)) {
audited = denied & avd->auditdeny;
/*
* a->selinux_audit_data.auditdeny is TRICKY! Setting a bit in
@@ -511,35 +546,12 @@ int avc_audit(u32 ssid, u32 tsid,
audited = denied = requested;
else
audited = requested & avd->auditallow;
- if (!audited)
+ if (likely(!audited))
return 0;
- if (!a) {
- a = &stack_data;
- COMMON_AUDIT_DATA_INIT(a, NONE);
- }
-
- /*
- * When in a RCU walk do the audit on the RCU retry. This is because
- * the collection of the dname in an inode audit message is not RCU
- * safe. Note this may drop some audits when the situation changes
- * during retry. However this is logically just as if the operation
- * happened a little later.
- */
- if ((a->type == LSM_AUDIT_DATA_INODE) &&
- (flags & IPERM_FLAG_RCU))
- return -ECHILD;
-
- a->selinux_audit_data.tclass = tclass;
- a->selinux_audit_data.requested = requested;
- a->selinux_audit_data.ssid = ssid;
- a->selinux_audit_data.tsid = tsid;
- a->selinux_audit_data.audited = audited;
- a->selinux_audit_data.denied = denied;
- a->lsm_pre_audit = avc_audit_pre_callback;
- a->lsm_post_audit = avc_audit_post_callback;
- common_lsm_audit(a);
- return 0;
+ return slow_avc_audit(ssid, tsid, tclass,
+ requested, audited, denied,
+ avd, a, flags);
}
/**