From 3091b667498b0a212e760e1033e5f9b8c33a948f Mon Sep 17 00:00:00 2001
From: Chuyi Zhou <zhouchuyi@bytedance.com>
Date: Tue, 31 Oct 2023 13:04:36 +0800
Subject: bpf: Relax allowlist for css_task iter
The newly added open-coded css_task iter would try to hold the global
css_set_lock in bpf_iter_css_task_new, so the bpf side has to be careful in
where it allows to use this iter. The mainly concern is dead locking on
css_set_lock. check_css_task_iter_allowlist() in verifier enforced css_task
can only be used in bpf_lsm hooks and sleepable bpf_iter.
This patch relax the allowlist for css_task iter. Any lsm and any iter
(even non-sleepable) and any sleepable are safe since they would not hold
the css_set_lock before entering BPF progs context.
This patch also fixes the misused BPF_TRACE_ITER in
check_css_task_iter_allowlist which compared bpf_prog_type with
bpf_attach_type.
Fixes: 9c66dc94b62ae ("bpf: Introduce css_task open-coded iterator kfuncs")
Signed-off-by: Chuyi Zhou <zhouchuyi@bytedance.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20231031050438.93297-2-zhouchuyi@bytedance.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---
tools/testing/selftests/bpf/progs/iters_task_failure.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
(limited to 'tools')
diff --git a/tools/testing/selftests/bpf/progs/iters_task_failure.c b/tools/testing/selftests/bpf/progs/iters_task_failure.c
index c3bf96a67dba..6b1588d70652 100644
--- a/tools/testing/selftests/bpf/progs/iters_task_failure.c
+++ b/tools/testing/selftests/bpf/progs/iters_task_failure.c
@@ -84,8 +84,8 @@ int BPF_PROG(iter_css_lock_and_unlock)
return 0;
}
-SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
-__failure __msg("css_task_iter is only allowed in bpf_lsm and bpf iter-s")
+SEC("?fentry/" SYS_PREFIX "sys_getpgid")
+__failure __msg("css_task_iter is only allowed in bpf_lsm, bpf_iter and sleepable progs")
int BPF_PROG(iter_css_task_for_each)
{
u64 cg_id = bpf_get_current_cgroup_id();
--
cgit