* [RFC,v2,1/1] audit: speed up syscall rule match while exiting syscall
@ 2021-01-21 13:54 yang.yang29
2021-01-22 17:02 ` [RFC, v2, 1/1] " Paul Moore
0 siblings, 1 reply; 3+ messages in thread
From: yang.yang29 @ 2021-01-21 13:54 UTC (permalink / raw)
To: paul; +Cc: linux-audit, linux-kernel
[-- Attachment #1.1: Type: text/plain, Size: 4407 bytes --]
From 72f3ecde58edb03d76cb359607fef98c1663d481 Mon Sep 17 00:00:00 2001
From: Yang Yang <yang.yang29@zte.com.cn>
Date: Thu, 21 Jan 2021 21:05:04 +0800
Subject: [PATCH] [RFC,v2,1/1] speed up syscall rule match while exiting syscall
audit_filter_syscall() traverses struct list_head audit_filter_list to find
out whether current syscall match one rule. This takes o(n), which is not
necessary, specially for user who add a very few syscall rules. On the other
hand, user may not much care about rule add/delete speed. So do o(n)
calculate at rule changing, and ease the burden of audit_filter_syscall().
Define audit_syscall[NR_syscalls], every element stands for one syscall.
audit_filter_syscall() checks audit_syscall[NR_syscalls].
audit_syscall[n] == 0 indicates no rule audit syscall n, do a quick exit.
audit_syscall[n] > 0 indicates at least one rule audit syscall n.
audit_syscall[n] update when syscall rule changes.
Signed-off-by: Yang Yang <yang.yang29@zte.com.cn>
---
include/linux/audit.h | 2 ++
kernel/audit.c | 4 ++++
kernel/auditfilter.c | 30 ++++++++++++++++++++++++++++++
kernel/auditsc.c | 5 ++++-
4 files changed, 40 insertions(+), 1 deletion(-)
diff --git a/include/linux/audit.h b/include/linux/audit.h
index 82b7c11..7885531 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -549,6 +549,8 @@ static inline void audit_log_nfcfg(const char *name, u8 af,
extern int audit_n_rules;
extern int audit_signals;
+extern u32 auditing_syscall[NR_syscalls];
+extern int audit_in_mask(const struct audit_krule *rule, unsigned long val);
#else /* CONFIG_AUDITSYSCALL */
static inline int audit_alloc(struct task_struct *task)
{
diff --git a/kernel/audit.c b/kernel/audit.c
index 1ffc2e0..07f4590 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -208,6 +208,10 @@ struct audit_reply {
struct sk_buff *skb;
};
+#ifdef CONFIG_AUDITSYSCALL
+u32 auditing_syscall[NR_syscalls] = {0};
+#endif
+
/**
* auditd_test_task - Check to see if a given task is an audit daemon
* @task: the task to check
diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
index 333b3bc..9d3e703 100644
--- a/kernel/auditfilter.c
+++ b/kernel/auditfilter.c
@@ -926,6 +926,28 @@ static struct audit_entry *audit_find_rule(struct audit_entry *entry,
static u64 prio_low = ~0ULL/2;
static u64 prio_high = ~0ULL/2 - 1;
+#ifdef CONFIG_AUDITSYSCALL
+static inline void update_auditing_syscall(struct audit_krule rule, bool add)
+{
+ int i;
+
+ /* syscall rule with type AUDIT_FILTER_EXIT */
+ if (rule.listnr == AUDIT_FILTER_EXIT && !rule.watch && !rule.tree) {
+ for (i = 0; i < NR_syscalls; i++) {
+ /* whether this rule include one syscall */
+ if (unlikely(audit_in_mask(&rule, i))) {
+ if (add == true)
+ auditing_syscall[i]++;
+ else
+ auditing_syscall[i]--;
+ }
+ }
+ }
+
+ return;
+}
+#endif
+
/* Add rule to given filterlist if not a duplicate. */
static inline int audit_add_rule(struct audit_entry *entry)
{
@@ -957,6 +979,10 @@ static inline int audit_add_rule(struct audit_entry *entry)
return err;
}
+#ifdef CONFIG_AUDITSYSCALL
+ update_auditing_syscall(entry->rule, true);
+#endif
+
if (watch) {
/* audit_filter_mutex is dropped and re-taken during this call */
err = audit_add_watch(&entry->rule, &list);
@@ -1035,6 +1061,10 @@ int audit_del_rule(struct audit_entry *entry)
goto out;
}
+#ifdef CONFIG_AUDITSYSCALL
+ update_auditing_syscall(e->rule, false);
+#endif
+
if (e->rule.watch)
audit_remove_watch_rule(&e->rule);
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index ce8c9e2..90490aa 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -783,7 +783,7 @@ static enum audit_state audit_filter_task(struct task_struct *tsk, char **key)
return AUDIT_BUILD_CONTEXT;
}
-static int audit_in_mask(const struct audit_krule *rule, unsigned long val)
+int audit_in_mask(const struct audit_krule *rule, unsigned long val)
{
int word, bit;
@@ -814,6 +814,9 @@ static enum audit_state audit_filter_syscall(struct task_struct *tsk,
if (auditd_test_task(tsk))
return AUDIT_DISABLED;
+ if (!auditing_syscall[ctx->major])
+ return AUDIT_BUILD_CONTEXT;
+
rcu_read_lock();
list_for_each_entry_rcu(e, list, list) {
if (audit_in_mask(&e->rule, ctx->major) &&
--
2.15.2
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https://www.redhat.com/mailman/listinfo/linux-audit
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [RFC,v2,1/1] audit: speed up syscall rule match while exiting syscall
2021-01-21 13:54 [RFC,v2,1/1] audit: speed up syscall rule match while exiting syscall yang.yang29
@ 2021-01-22 17:02 ` Paul Moore
0 siblings, 0 replies; 3+ messages in thread
From: Paul Moore @ 2021-01-22 17:02 UTC (permalink / raw)
To: yang.yang29; +Cc: linux-audit, linux-kernel
On Thu, Jan 21, 2021 at 8:54 AM <yang.yang29@zte.com.cn> wrote:
>
> From 72f3ecde58edb03d76cb359607fef98c1663d481 Mon Sep 17 00:00:00 2001
> From: Yang Yang <yang.yang29@zte.com.cn>
> Date: Thu, 21 Jan 2021 21:05:04 +0800
> Subject: [PATCH] [RFC,v2,1/1] speed up syscall rule match while exiting syscall
> audit_filter_syscall() traverses struct list_head audit_filter_list to find
> out whether current syscall match one rule. This takes o(n), which is not
> necessary, specially for user who add a very few syscall rules. On the other
> hand, user may not much care about rule add/delete speed. So do o(n)
> calculate at rule changing, and ease the burden of audit_filter_syscall().
>
> Define audit_syscall[NR_syscalls], every element stands for one syscall.
> audit_filter_syscall() checks audit_syscall[NR_syscalls].
> audit_syscall[n] == 0 indicates no rule audit syscall n, do a quick exit.
> audit_syscall[n] > 0 indicates at least one rule audit syscall n.
> audit_syscall[n] update when syscall rule changes.
>
> Signed-off-by: Yang Yang <yang.yang29@zte.com.cn>
> ---
> include/linux/audit.h | 2 ++
> kernel/audit.c | 4 ++++
> kernel/auditfilter.c | 30 ++++++++++++++++++++++++++++++
> kernel/auditsc.c | 5 ++++-
> 4 files changed, 40 insertions(+), 1 deletion(-)
...
> diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
> index 333b3bc..9d3e703 100644
> --- a/kernel/auditfilter.c
> +++ b/kernel/auditfilter.c
> @@ -926,6 +926,28 @@ static struct audit_entry *audit_find_rule(struct audit_entry *entry,
> static u64 prio_low = ~0ULL/2;
> static u64 prio_high = ~0ULL/2 - 1;
>
> +#ifdef CONFIG_AUDITSYSCALL
> +static inline void update_auditing_syscall(struct audit_krule rule, bool add)
> +{
> + int i;
> +
> + /* syscall rule with type AUDIT_FILTER_EXIT */
> + if (rule.listnr == AUDIT_FILTER_EXIT && !rule.watch && !rule.tree) {
> + for (i = 0; i < NR_syscalls; i++) {
> + /* whether this rule include one syscall */
> + if (unlikely(audit_in_mask(&rule, i))) {
> + if (add == true)
> + auditing_syscall[i]++;
> + else
> + auditing_syscall[i]--;
> + }
> + }
> + }
> +
> + return;
> +}
> +#endif
> +
> /* Add rule to given filterlist if not a duplicate. */
> static inline int audit_add_rule(struct audit_entry *entry)
> {
> @@ -957,6 +979,10 @@ static inline int audit_add_rule(struct audit_entry *entry)
> return err;
> }
>
> +#ifdef CONFIG_AUDITSYSCALL
> + update_auditing_syscall(entry->rule, true);
> +#endif
I'm going to reply to your other email where we are discussing the
performance of this patch, but I wanted to make one comment about the
approach you've taken with the update_auditing_syscall() here.
First, naming things is hard, but the chosen name is not a good one in
my opinion. Something like audit_rule_syscall_mask_update() would
probably be a better fit.
Second, in order to minimize preprocessor clutter, it is better to use
the following pattern:
#ifdef CONFIG_FOO
int func(int arg)
{
/* important stuff */
}
#else
int func(int arg)
{
return 0; /* appropriate return value */
}
#endif
There are probably a few other comments on this patch, but I want us
to discuss the performance impacts of this first as I'm not convinced
this is a solution we want upstream.
--
paul moore
www.paul-moore.com
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [RFC, v2, 1/1] audit: speed up syscall rule match while exiting syscall
@ 2021-01-22 17:02 ` Paul Moore
0 siblings, 0 replies; 3+ messages in thread
From: Paul Moore @ 2021-01-22 17:02 UTC (permalink / raw)
To: yang.yang29; +Cc: linux-audit, linux-kernel
On Thu, Jan 21, 2021 at 8:54 AM <yang.yang29@zte.com.cn> wrote:
>
> From 72f3ecde58edb03d76cb359607fef98c1663d481 Mon Sep 17 00:00:00 2001
> From: Yang Yang <yang.yang29@zte.com.cn>
> Date: Thu, 21 Jan 2021 21:05:04 +0800
> Subject: [PATCH] [RFC,v2,1/1] speed up syscall rule match while exiting syscall
> audit_filter_syscall() traverses struct list_head audit_filter_list to find
> out whether current syscall match one rule. This takes o(n), which is not
> necessary, specially for user who add a very few syscall rules. On the other
> hand, user may not much care about rule add/delete speed. So do o(n)
> calculate at rule changing, and ease the burden of audit_filter_syscall().
>
> Define audit_syscall[NR_syscalls], every element stands for one syscall.
> audit_filter_syscall() checks audit_syscall[NR_syscalls].
> audit_syscall[n] == 0 indicates no rule audit syscall n, do a quick exit.
> audit_syscall[n] > 0 indicates at least one rule audit syscall n.
> audit_syscall[n] update when syscall rule changes.
>
> Signed-off-by: Yang Yang <yang.yang29@zte.com.cn>
> ---
> include/linux/audit.h | 2 ++
> kernel/audit.c | 4 ++++
> kernel/auditfilter.c | 30 ++++++++++++++++++++++++++++++
> kernel/auditsc.c | 5 ++++-
> 4 files changed, 40 insertions(+), 1 deletion(-)
...
> diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
> index 333b3bc..9d3e703 100644
> --- a/kernel/auditfilter.c
> +++ b/kernel/auditfilter.c
> @@ -926,6 +926,28 @@ static struct audit_entry *audit_find_rule(struct audit_entry *entry,
> static u64 prio_low = ~0ULL/2;
> static u64 prio_high = ~0ULL/2 - 1;
>
> +#ifdef CONFIG_AUDITSYSCALL
> +static inline void update_auditing_syscall(struct audit_krule rule, bool add)
> +{
> + int i;
> +
> + /* syscall rule with type AUDIT_FILTER_EXIT */
> + if (rule.listnr == AUDIT_FILTER_EXIT && !rule.watch && !rule.tree) {
> + for (i = 0; i < NR_syscalls; i++) {
> + /* whether this rule include one syscall */
> + if (unlikely(audit_in_mask(&rule, i))) {
> + if (add == true)
> + auditing_syscall[i]++;
> + else
> + auditing_syscall[i]--;
> + }
> + }
> + }
> +
> + return;
> +}
> +#endif
> +
> /* Add rule to given filterlist if not a duplicate. */
> static inline int audit_add_rule(struct audit_entry *entry)
> {
> @@ -957,6 +979,10 @@ static inline int audit_add_rule(struct audit_entry *entry)
> return err;
> }
>
> +#ifdef CONFIG_AUDITSYSCALL
> + update_auditing_syscall(entry->rule, true);
> +#endif
I'm going to reply to your other email where we are discussing the
performance of this patch, but I wanted to make one comment about the
approach you've taken with the update_auditing_syscall() here.
First, naming things is hard, but the chosen name is not a good one in
my opinion. Something like audit_rule_syscall_mask_update() would
probably be a better fit.
Second, in order to minimize preprocessor clutter, it is better to use
the following pattern:
#ifdef CONFIG_FOO
int func(int arg)
{
/* important stuff */
}
#else
int func(int arg)
{
return 0; /* appropriate return value */
}
#endif
There are probably a few other comments on this patch, but I want us
to discuss the performance impacts of this first as I'm not convinced
this is a solution we want upstream.
--
paul moore
www.paul-moore.com
--
Linux-audit mailing list
Linux-audit@redhat.com
https://www.redhat.com/mailman/listinfo/linux-audit
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2021-01-22 17:14 UTC | newest]
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2021-01-21 13:54 [RFC,v2,1/1] audit: speed up syscall rule match while exiting syscall yang.yang29
2021-01-22 17:02 ` Paul Moore
2021-01-22 17:02 ` [RFC, v2, 1/1] " Paul Moore
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