bpf: Replace prog_raw_tp+btf_id with prog_tracing

The bpf program type raw_tp together with 'expected_attach_type'
was the most appropriate api to indicate BTF-enabled raw_tp programs.
But during development it became apparent that 'expected_attach_type'
cannot be used and new 'attach_btf_id' field had to be introduced.
Which means that the information is duplicated in two fields where
one of them is ignored.
Clean it up by introducing new program type where both
'expected_attach_type' and 'attach_btf_id' fields have
specific meaning.
In the future 'expected_attach_type' will be extended
with other attach points that have similar semantics to raw_tp.
This patch is replacing BTF-enabled BPF_PROG_TYPE_RAW_TRACEPOINT with
prog_type = BPF_RPOG_TYPE_TRACING
expected_attach_type = BPF_TRACE_RAW_TP
attach_btf_id = btf_id of raw tracepoint inside the kernel
Future patches will add
expected_attach_type = BPF_TRACE_FENTRY or BPF_TRACE_FEXIT
where programs have the same input context and the same helpers,
but different attach points.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20191030223212.953010-2-ast@kernel.org

1 files changed, 36 insertions, 8 deletions

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 571c25d60710..f50bf19f7a05 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1055,10 +1055,6 @@ raw_tp_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 	switch (func_id) {
 	case BPF_FUNC_perf_event_output:
 		return &bpf_perf_event_output_proto_raw_tp;
-#ifdef CONFIG_NET
-	case BPF_FUNC_skb_output:
-		return &bpf_skb_output_proto;
-#endif
 	case BPF_FUNC_get_stackid:
 		return &bpf_get_stackid_proto_raw_tp;
 	case BPF_FUNC_get_stack:
@@ -1068,20 +1064,44 @@ raw_tp_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 	}
 }
 
+static const struct bpf_func_proto *
+tracing_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
+{
+	switch (func_id) {
+#ifdef CONFIG_NET
+	case BPF_FUNC_skb_output:
+		return &bpf_skb_output_proto;
+#endif
+	default:
+		return raw_tp_prog_func_proto(func_id, prog);
+	}
+}
+
 static bool raw_tp_prog_is_valid_access(int off, int size,
 					enum bpf_access_type type,
 					const struct bpf_prog *prog,
 					struct bpf_insn_access_aux *info)
 {
-	/* largest tracepoint in the kernel has 12 args */
-	if (off < 0 || off >= sizeof(__u64) * 12)
+	if (off < 0 || off >= sizeof(__u64) * MAX_BPF_FUNC_ARGS)
+		return false;
+	if (type != BPF_READ)
+		return false;
+	if (off % size != 0)
+		return false;
+	return true;
+}
+
+static bool tracing_prog_is_valid_access(int off, int size,
+					 enum bpf_access_type type,
+					 const struct bpf_prog *prog,
+					 struct bpf_insn_access_aux *info)
+{
+	if (off < 0 || off >= sizeof(__u64) * MAX_BPF_FUNC_ARGS)
 		return false;
 	if (type != BPF_READ)
 		return false;
 	if (off % size != 0)
 		return false;
-	if (!prog->aux->attach_btf_id)
-		return true;
 	return btf_ctx_access(off, size, type, prog, info);
 }
 
@@ -1093,6 +1113,14 @@ const struct bpf_verifier_ops raw_tracepoint_verifier_ops = {
 const struct bpf_prog_ops raw_tracepoint_prog_ops = {
 };
 
+const struct bpf_verifier_ops tracing_verifier_ops = {
+	.get_func_proto  = tracing_prog_func_proto,
+	.is_valid_access = tracing_prog_is_valid_access,
+};
+
+const struct bpf_prog_ops tracing_prog_ops = {
+};
+
 static bool raw_tp_writable_prog_is_valid_access(int off, int size,
 						 enum bpf_access_type type,
 						 const struct bpf_prog *prog,