On Thu, 2009-02-12 at 14:50 -0500, Eric Paris wrote:
> we are often needlessly jumping through hoops when it comes to avd
> entries in avc_has_perm_noaudit and we have extra initialization and memcpy
> which are just wasting performance. Try to clean the function up a bit.
>
> This patch resulted in a 13% drop in time spent in avc_has_perm_noaudit in my
> oprofile sampling of a tbench benchmark.
Further improvement might be to eliminate the need to return an avd at
all from avc_has_perm_noaudit(); there is only one user left and that
could be handled inside of avc_has_perm if it just passed in a flag
indicating audit vs no-audit (as in the original AVC).
>
> Signed-off-by: Eric Paris <eparis@xxxxxxxxxx>
Acked-by: Stephen Smalley <sds@xxxxxxxxxxxxx>
> ---
>
> security/selinux/avc.c | 43 ++++++++++++++++++++++++-------------------
> 1 files changed, 24 insertions(+), 19 deletions(-)
>
> diff --git a/security/selinux/avc.c b/security/selinux/avc.c
> index abfe378..332c3cd 100644
> --- a/security/selinux/avc.c
> +++ b/security/selinux/avc.c
> @@ -355,12 +355,12 @@ out:
> return node;
> }
>
> -static void avc_node_populate(struct avc_node *node, u32 ssid, u32 tsid, u16 tclass, struct avc_entry *ae)
> +static void avc_node_populate(struct avc_node *node, u32 ssid, u32 tsid, u16 tclass, struct av_decision *avd)
> {
> node->ae.ssid = ssid;
> node->ae.tsid = tsid;
> node->ae.tclass = tclass;
> - memcpy(&node->ae.avd, &ae->avd, sizeof(node->ae.avd));
> + memcpy(&node->ae.avd, avd, sizeof(node->ae.avd));
> }
>
> static inline struct avc_node *avc_search_node(u32 ssid, u32 tsid, u16 tclass)
> @@ -440,31 +440,31 @@ static int avc_latest_notif_update(int seqno, int is_insert)
> * @ssid: source security identifier
> * @tsid: target security identifier
> * @tclass: target security class
> - * @ae: AVC entry
> + * @avd: resulting av decision
> *
> * Insert an AVC entry for the SID pair
> * (@ssid, @tsid) and class @tclass.
> * The access vectors and the sequence number are
> * normally provided by the security server in
> * response to a security_compute_av() call. If the
> - * sequence number @ae->avd.seqno is not less than the latest
> + * sequence number @avd->seqno is not less than the latest
> * revocation notification, then the function copies
> * the access vectors into a cache entry, returns
> * avc_node inserted. Otherwise, this function returns NULL.
> */
> -static struct avc_node *avc_insert(u32 ssid, u32 tsid, u16 tclass, struct avc_entry *ae)
> +static struct avc_node *avc_insert(u32 ssid, u32 tsid, u16 tclass, struct av_decision *avd)
> {
> struct avc_node *pos, *node = NULL;
> int hvalue;
> unsigned long flag;
>
> - if (avc_latest_notif_update(ae->avd.seqno, 1))
> + if (avc_latest_notif_update(avd->seqno, 1))
> goto out;
>
> node = avc_alloc_node();
> if (node) {
> hvalue = avc_hash(ssid, tsid, tclass);
> - avc_node_populate(node, ssid, tsid, tclass, ae);
> + avc_node_populate(node, ssid, tsid, tclass, avd);
>
> spin_lock_irqsave(&avc_cache.slots_lock[hvalue], flag);
> list_for_each_entry(pos, &avc_cache.slots[hvalue], list) {
> @@ -777,7 +777,7 @@ static int avc_update_node(u32 event, u32 perms, u32 ssid, u32 tsid, u16 tclass,
> * Copy and replace original node.
> */
>
> - avc_node_populate(node, ssid, tsid, tclass, &orig->ae);
> + avc_node_populate(node, ssid, tsid, tclass, &orig->ae.avd);
>
> switch (event) {
> case AVC_CALLBACK_GRANT:
> @@ -869,10 +869,10 @@ int avc_ss_reset(u32 seqno)
> int avc_has_perm_noaudit(u32 ssid, u32 tsid,
> u16 tclass, u32 requested,
> unsigned flags,
> - struct av_decision *avd)
> + struct av_decision *in_avd)
> {
> struct avc_node *node;
> - struct avc_entry entry, *p_ae;
> + struct av_decision avd_entry, *avd;
> int rc = 0;
> u32 denied;
>
> @@ -883,26 +883,31 @@ int avc_has_perm_noaudit(u32 ssid, u32 tsid,
> node = avc_lookup(ssid, tsid, tclass, requested);
> if (!node) {
> rcu_read_unlock();
> - rc = security_compute_av(ssid, tsid, tclass, requested, &entry.avd);
> +
> + if (in_avd)
> + avd = in_avd;
> + else
> + avd = &avd_entry;
> +
> + rc = security_compute_av(ssid, tsid, tclass, requested, avd);
> if (rc)
> goto out;
> rcu_read_lock();
> - node = avc_insert(ssid, tsid, tclass, &entry);
> + node = avc_insert(ssid, tsid, tclass, avd);
> + } else {
> + if (in_avd)
> + memcpy(in_avd, &node->ae.avd, sizeof(*in_avd));
> + avd = &node->ae.avd;
> }
>
> - p_ae = node ? &node->ae : &entry;
> -
> - if (avd)
> - memcpy(avd, &p_ae->avd, sizeof(*avd));
> -
> - denied = requested & ~(p_ae->avd.allowed);
> + denied = requested & ~(avd->allowed);
>
> if (denied) {
> if (flags & AVC_STRICT)
> rc = -EACCES;
> else if (!selinux_enforcing || security_permissive_sid(ssid))
> avc_update_node(AVC_CALLBACK_GRANT, requested, ssid,
> - tsid, tclass, p_ae->avd.seqno);
> + tsid, tclass, avd->seqno);
> else
> rc = -EACCES;
> }
--
Stephen Smalley
National Security Agency
--
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