bpf: Refactor ARG_PTR_TO_DYNPTR checks into process_dynptr_func

ARG_PTR_TO_DYNPTR is akin to ARG_PTR_TO_TIMER, ARG_PTR_TO_KPTR, where
the underlying register type is subjected to more special checks to
determine the type of object represented by the pointer and its state
consistency.

Move dynptr checks to their own 'process_dynptr_func' function so that
is consistent and in-line with existing code. This also makes it easier
to reuse this code for kfunc handling.

Then, reuse this consolidated function in kfunc dynptr handling too.
Note that for kfuncs, the arg_type constraint of DYNPTR_TYPE_LOCAL has
been lifted.

Acked-by: David Vernet <void@manifault.com>
Acked-by: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20221207204141.308952-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

2 files changed, 2 insertions, 17 deletions

diff --git a/tools/testing/selftests/bpf/prog_tests/kfunc_dynptr_param.c b/tools/testing/selftests/bpf/prog_tests/kfunc_dynptr_param.c
index 55d641c1f126..a9229260a6ce 100644
--- a/tools/testing/selftests/bpf/prog_tests/kfunc_dynptr_param.c
+++ b/tools/testing/selftests/bpf/prog_tests/kfunc_dynptr_param.c
@@ -18,11 +18,8 @@ static struct {
 	const char *expected_verifier_err_msg;
 	int expected_runtime_err;
 } kfunc_dynptr_tests[] = {
-	{"dynptr_type_not_supp",
-	 "arg#0 pointer type STRUCT bpf_dynptr_kern points to unsupported dynamic pointer type", 0},
-	{"not_valid_dynptr",
-	 "arg#0 pointer type STRUCT bpf_dynptr_kern must be valid and initialized", 0},
-	{"not_ptr_to_stack", "arg#0 expected pointer to stack", 0},
+	{"not_valid_dynptr", "Expected an initialized dynptr as arg #1", 0},
+	{"not_ptr_to_stack", "arg#0 expected pointer to stack or dynptr_ptr", 0},
 	{"dynptr_data_null", NULL, -EBADMSG},
 };
 
diff --git a/tools/testing/selftests/bpf/progs/test_kfunc_dynptr_param.c b/tools/testing/selftests/bpf/progs/test_kfunc_dynptr_param.c
index ce39d096bba3..f4a8250329b2 100644
--- a/tools/testing/selftests/bpf/progs/test_kfunc_dynptr_param.c
+++ b/tools/testing/selftests/bpf/progs/test_kfunc_dynptr_param.c
@@ -33,18 +33,6 @@ int err, pid;
 char _license[] SEC("license") = "GPL";
 
 SEC("?lsm.s/bpf")
-int BPF_PROG(dynptr_type_not_supp, int cmd, union bpf_attr *attr,
-	     unsigned int size)
-{
-	char write_data[64] = "hello there, world!!";
-	struct bpf_dynptr ptr;
-
-	bpf_ringbuf_reserve_dynptr(&ringbuf, sizeof(write_data), 0, &ptr);
-
-	return bpf_verify_pkcs7_signature(&ptr, &ptr, NULL);
-}
-
-SEC("?lsm.s/bpf")
 int BPF_PROG(not_valid_dynptr, int cmd, union bpf_attr *attr, unsigned int size)
 {
 	unsigned long val;