bpf: Expose bpf_sk_storage_* to iterator programs

Iterators are currently used to expose kernel information to userspace
over fast procfs-like files but iterators could also be used to
initialize local storage. For example, the task_file iterator could be
used to store associations between processes and sockets.

This exposes the socket local storage helpers to all iterators. Martin
Kafai checked that this was safe to call these helpers from the
sk_storage_map iterators.

Signed-off-by: Florent Revest <revest@google.com>

Author: Florent Revest

kernel/trace/bpf_trace.c

@@ -17,6 +17,8 @@
 #include <linux/error-injection.h>
 #include <linux/btf_ids.h>
 
+#include <net/bpf_sk_storage.h>
+
 #include <uapi/linux/bpf.h>
 #include <uapi/linux/btf.h>
 
@@ -1750,6 +1752,14 @@ tracing_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 		       NULL;
 	case BPF_FUNC_d_path:
 		return &bpf_d_path_proto;
+	case BPF_FUNC_sk_storage_get:
+		return prog->expected_attach_type == BPF_TRACE_ITER ?
+		       &bpf_sk_storage_get_proto :
+		       NULL;
+	case BPF_FUNC_sk_storage_delete:
+		return prog->expected_attach_type == BPF_TRACE_ITER ?
+		       &bpf_sk_storage_delete_proto :
+		       NULL;
 	default:
 		return raw_tp_prog_func_proto(func_id, prog);
 	}