Re: [PATCH 3/3] audit: unify audit_filter_{uring(), inode_name(), syscall()}
On Tue, Sep 27, 2022 at 7:00 PM Ankur Arora <ankur.a.arora(a)oracle.com> wrote:
audit_filter_uring(), audit_filter_inode_name() are substantially similar
to audit_filter_syscall(). Move the core logic to __audit_filter() which
can be parametrized for all three.
On a Skylakex system, getpid() latency (all results aggregated
across 12 boot cycles):
Min Mean Median Max pstdev
(ns) (ns) (ns) (ns)
- 173.11 182.51 179.65 202.09 (+- 4.34%)
+ 162.11 175.26 173.71 190.56 (+- 4.33%)
Performance counter stats for 'bin/getpid' (3 runs) go from:
cycles 706.13 ( +- 4.13% )
instructions 1654.70 ( +- .06% )
IPC 2.35 ( +- 4.25% )
branches 430.99 ( +- .06% )
branch-misses 0.50 ( +- 2.00% )
L1-dcache-loads 440.02 ( +- .07% )
L1-dcache-load-misses 5.22 ( +- 82.75% )
to:
cycles 678.79 ( +- 4.22% )
instructions 1657.79 ( +- .05% )
IPC 2.45 ( +- 4.08% )
branches 432.00 ( +- .05% )
branch-misses 0.38 ( +- 23.68% )
L1-dcache-loads 444.96 ( +- .03% )
L1-dcache-load-misses 5.13 ( +- 73.09% )
(Both aggregated over 12 boot cycles.)
Unclear if the improvement is just run-to-run variation or because of
a slightly denser loop (the list parameter in the list_for_each_entry_rcu()
exit check now comes from a register rather than a constant as before.)
Signed-off-by: Ankur Arora <ankur.a.arora(a)oracle.com>
---
kernel/auditsc.c | 86 +++++++++++++++++++++++++-----------------------
1 file changed, 44 insertions(+), 42 deletions(-)
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index bf26f47b5226..dd89a52988b0 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -805,6 +805,41 @@ static bool audit_in_mask(const struct audit_krule *rule, unsigned
long val)
return rule->mask[word] & bit;
}
+/**
+ * __audit_filter - common filter
+ *
Please remove the vertical whitespace between the function description
line and the parameter descriptions.
I'd also suggest renaming this function to "__audit_filter_op(...)"
since we have a few audit filtering functions and a generic
"__audit_filter()" function with no qualification in the name seems
just a bit too generic to not be misleading ... at least I think so.
I also might try to be just a bit more descriptive in the text above,
for example:
"__audit_filter_op - filter helper function for operations
(syscall/uring/etc.)"
+ * @tsk: associated task
+ * @ctx: audit context
+ * @list: audit filter list
+ * @op: current syscall/uring_op
+ * @name: name to be filtered (used by audit_filter_inode_name)
I would change this to "@name: audit_name to use in filtering (can be
NULL)" and leave it at that.
+ *
+ * return: 1 if we hit a filter, 0 if we don't
The function header block comment description should be in regular
English sentences. Perhaps something like this:
"Run the audit filters specified in @list against @tsk using @ctx,
@op, and @name as necessary; the caller is responsible for ensuring
that the call is made while the RCU read lock is held. The @name
parameter can be NULL, but all others must be specified. Returns
1/true if the filter finds a match, 0/false if none are found."
+ */
+static int __audit_filter(struct task_struct *tsk,
+ struct audit_context *ctx,
+ struct list_head *list,
+ unsigned long op,
+ struct audit_names *name)
+{
+ struct audit_entry *e;
+ enum audit_state state;
+
+ rcu_read_lock();
I would move the RCU locking to the callers since not every caller requires it.
+ list_for_each_entry_rcu(e, list, list) {
+ if (unlikely(audit_in_mask(&e->rule, op))) {
As discussed in patch 2/3, please remove the unlikely() call.
+ if (audit_filter_rules(tsk, &e->rule,
ctx, name,
+ &state, false)) {
+ rcu_read_unlock();
+ ctx->current_state = state;
+ return 1;
+ }
+ }
+ }
+ rcu_read_unlock();
+ return 0;
+}
+
--
paul-moore.com