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

2 files changed, 27 insertions, 13 deletions

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index ff5225759553..985d01ced196 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1571,7 +1571,7 @@ bpf_prog_load_check_attach(enum bpf_prog_type prog_type,
 			   u32 btf_id)
 {
 	switch (prog_type) {
-	case BPF_PROG_TYPE_RAW_TRACEPOINT:
+	case BPF_PROG_TYPE_TRACING:
 		if (btf_id > BTF_MAX_TYPE)
 			return -EINVAL;
 		break;
@@ -1833,13 +1833,13 @@ static int bpf_raw_tracepoint_open(const union bpf_attr *attr)
 		return PTR_ERR(prog);
 
 	if (prog->type != BPF_PROG_TYPE_RAW_TRACEPOINT &&
+	    prog->type != BPF_PROG_TYPE_TRACING &&
 	    prog->type != BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE) {
 		err = -EINVAL;
 		goto out_put_prog;
 	}
 
-	if (prog->type == BPF_PROG_TYPE_RAW_TRACEPOINT &&
-	    prog->aux->attach_btf_id) {
+	if (prog->type == BPF_PROG_TYPE_TRACING) {
 		if (attr->raw_tracepoint.name) {
 			/* raw_tp name should not be specified in raw_tp
 			 * programs that were verified via in-kernel BTF info
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 6b0de04f8b91..2f2374967b36 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -9381,24 +9381,36 @@ static int check_attach_btf_id(struct bpf_verifier_env *env)
 {
 	struct bpf_prog *prog = env->prog;
 	u32 btf_id = prog->aux->attach_btf_id;
+	const char prefix[] = "btf_trace_";
 	const struct btf_type *t;
 	const char *tname;
 
-	if (prog->type == BPF_PROG_TYPE_RAW_TRACEPOINT && btf_id) {
-		const char prefix[] = "btf_trace_";
+	if (prog->type != BPF_PROG_TYPE_TRACING)
+		return 0;
 
-		t = btf_type_by_id(btf_vmlinux, btf_id);
-		if (!t) {
-			verbose(env, "attach_btf_id %u is invalid\n", btf_id);
-			return -EINVAL;
-		}
+	if (!btf_id) {
+		verbose(env, "Tracing programs must provide btf_id\n");
+		return -EINVAL;
+	}
+	t = btf_type_by_id(btf_vmlinux, btf_id);
+	if (!t) {
+		verbose(env, "attach_btf_id %u is invalid\n", btf_id);
+		return -EINVAL;
+	}
+	tname = btf_name_by_offset(btf_vmlinux, t->name_off);
+	if (!tname) {
+		verbose(env, "attach_btf_id %u doesn't have a name\n", btf_id);
+		return -EINVAL;
+	}
+
+	switch (prog->expected_attach_type) {
+	case BPF_TRACE_RAW_TP:
 		if (!btf_type_is_typedef(t)) {
 			verbose(env, "attach_btf_id %u is not a typedef\n",
 				btf_id);
 			return -EINVAL;
 		}
-		tname = btf_name_by_offset(btf_vmlinux, t->name_off);
-		if (!tname || strncmp(prefix, tname, sizeof(prefix) - 1)) {
+		if (strncmp(prefix, tname, sizeof(prefix) - 1)) {
 			verbose(env, "attach_btf_id %u points to wrong type name %s\n",
 				btf_id, tname);
 			return -EINVAL;
@@ -9419,8 +9431,10 @@ static int check_attach_btf_id(struct bpf_verifier_env *env)
 		prog->aux->attach_func_name = tname;
 		prog->aux->attach_func_proto = t;
 		prog->aux->attach_btf_trace = true;
+		return 0;
+	default:
+		return -EINVAL;
 	}
-	return 0;
 }
 
 int bpf_check(struct bpf_prog **prog, union bpf_attr *attr,