On 12/13/23 6:38 AM, Michael Weiß wrote:
This helper can be used to check if a cgroup-bpf specific program is
active for the current task.
Signed-off-by: Michael Weiß <michael.weiss@xxxxxxxxxxxxxxxxxxx>
Reviewed-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@xxxxxxxxxxxxx>
---
include/linux/bpf-cgroup.h | 2 ++
kernel/bpf/cgroup.c | 14 ++++++++++++++
2 files changed, 16 insertions(+)
diff --git a/include/linux/bpf-cgroup.h b/include/linux/bpf-cgroup.h
index a789266feac3..7cb49bde09ff 100644
--- a/include/linux/bpf-cgroup.h
+++ b/include/linux/bpf-cgroup.h
@@ -191,6 +191,8 @@ static inline bool cgroup_bpf_sock_enabled(struct sock *sk,
return array != &bpf_empty_prog_array.hdr;
}
+bool cgroup_bpf_current_enabled(enum cgroup_bpf_attach_type type);
+
/* Wrappers for __cgroup_bpf_run_filter_skb() guarded by cgroup_bpf_enabled. */
#define BPF_CGROUP_RUN_PROG_INET_INGRESS(sk, skb) \
({ \
diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
index 491d20038cbe..9007165abe8c 100644
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -24,6 +24,20 @@
DEFINE_STATIC_KEY_ARRAY_FALSE(cgroup_bpf_enabled_key, MAX_CGROUP_BPF_ATTACH_TYPE);
EXPORT_SYMBOL(cgroup_bpf_enabled_key);
+bool cgroup_bpf_current_enabled(enum cgroup_bpf_attach_type type)
+{
+ struct cgroup *cgrp;
+ struct bpf_prog_array *array;
+
+ rcu_read_lock();
+ cgrp = task_dfl_cgroup(current);
+ rcu_read_unlock();
+
+ array = rcu_access_pointer(cgrp->bpf.effective[type]);
This seems wrong here. The cgrp could become invalid once leaving
rcu critical section.
+ return array != &bpf_empty_prog_array.hdr;
I guess you need include 'array' usage as well in the rcu cs.
So overall should look like:
rcu_read_lock();
cgrp = task_dfl_cgroup(current);
array = rcu_access_pointer(cgrp->bpf.effective[type]);
bpf_prog_exists = array != &bpf_empty_prog_array.hdr;
rcu_read_unlock();
return bpf_prog_exists;
+}
+EXPORT_SYMBOL(cgroup_bpf_current_enabled);
+
/* __always_inline is necessary to prevent indirect call through run_prog
* function pointer.
*/
