bpf: Add new bpf_task_storage_get proto with no deadlock detection
The bpf_lsm and bpf_iter do not recur that will cause a deadlock.
The situation is similar to the bpf_pid_task_storage_lookup_elem()
which is called from the syscall map_lookup_elem. It does not need
deadlock detection. Otherwise, it will cause unnecessary failure
when calling the bpf_task_storage_get() helper.
This patch adds bpf_task_storage_get proto that does not do deadlock
detection. It will be used by bpf_lsm and bpf_iter programs.
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20221025184524.3526117-6-martin.lau@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
diff --git a/kernel/bpf/bpf_task_storage.c b/kernel/bpf/bpf_task_storage.c
index bc52bc8..c3a841b 100644
--- a/kernel/bpf/bpf_task_storage.c
+++ b/kernel/bpf/bpf_task_storage.c
@@ -269,6 +269,23 @@ BPF_CALL_5(bpf_task_storage_get_recur, struct bpf_map *, map, struct task_struct
return (unsigned long)data;
}
+/* *gfp_flags* is a hidden argument provided by the verifier */
+BPF_CALL_5(bpf_task_storage_get, struct bpf_map *, map, struct task_struct *,
+ task, void *, value, u64, flags, gfp_t, gfp_flags)
+{
+ void *data;
+
+ WARN_ON_ONCE(!bpf_rcu_lock_held());
+ if (flags & ~BPF_LOCAL_STORAGE_GET_F_CREATE || !task)
+ return (unsigned long)NULL;
+
+ bpf_task_storage_lock();
+ data = __bpf_task_storage_get(map, task, value, flags,
+ gfp_flags, true);
+ bpf_task_storage_unlock();
+ return (unsigned long)data;
+}
+
BPF_CALL_2(bpf_task_storage_delete_recur, struct bpf_map *, map, struct task_struct *,
task)
{
@@ -342,6 +359,17 @@ const struct bpf_func_proto bpf_task_storage_get_recur_proto = {
.arg4_type = ARG_ANYTHING,
};
+const struct bpf_func_proto bpf_task_storage_get_proto = {
+ .func = bpf_task_storage_get,
+ .gpl_only = false,
+ .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
+ .arg1_type = ARG_CONST_MAP_PTR,
+ .arg2_type = ARG_PTR_TO_BTF_ID,
+ .arg2_btf_id = &btf_tracing_ids[BTF_TRACING_TYPE_TASK],
+ .arg3_type = ARG_PTR_TO_MAP_VALUE_OR_NULL,
+ .arg4_type = ARG_ANYTHING,
+};
+
const struct bpf_func_proto bpf_task_storage_delete_recur_proto = {
.func = bpf_task_storage_delete_recur,
.gpl_only = false,
