linux-kernel - [PATCH bpf-next] bpf: replace open code with for allocated object check

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Date:   Sat, 27 May 2023 21:27:06 +0900
From:   "Daniel T. Lee" <danieltimlee@...il.com>
To:     Daniel Borkmann <daniel@...earbox.net>,
        Alexei Starovoitov <ast@...nel.org>,
        Andrii Nakryiko <andrii.nakryiko@...il.com>,
        John Fastabend <john.fastabend@...il.com>,
        Stanislav Fomichev <sdf@...gle.com>,
        KP Singh <kpsingh@...nel.org>, Yonghong Song <yhs@...com>,
        Song Liu <song@...nel.org>,
        Martin KaFai Lau <martin.lau@...ux.dev>,
        Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>
Cc:     bpf@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH bpf-next] bpf: replace open code with for allocated object check

>From commit 282de143ead9 ("bpf: Introduce allocated objects support"),
With this allocated object with BPF program, (PTR_TO_BTF_ID | MEM_ALLOC)
has been a way of indicating to check the type is the allocated object.

commit d8939cb0a03c ("bpf: Loosen alloc obj test in verifier's
reg_btf_record")
>From the commit, there has been helper function for checking this, named
type_is_ptr_alloc_obj(). But still, some of the code use open code to
retrieve this info. This commit replaces the open code with the
type_is_alloc(), and the type_is_ptr_alloc_obj() function.

Signed-off-by: Daniel T. Lee <danieltimlee@...il.com>
---
 kernel/bpf/verifier.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 086b2a14905b..97c714e8a8bf 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -5891,7 +5891,7 @@ static int check_ptr_to_btf_access(struct bpf_verifier_env *env,
 		 * program allocated objects (which always have ref_obj_id > 0),
 		 * but not for untrusted PTR_TO_BTF_ID | MEM_ALLOC.
 		 */
-		if (atype != BPF_READ && reg->type != (PTR_TO_BTF_ID | MEM_ALLOC)) {
+		if (atype != BPF_READ && !type_is_ptr_alloc_obj(reg->type)) {
 			verbose(env, "only read is supported\n");
 			return -EACCES;
 		}
@@ -7511,7 +7511,7 @@ static int check_reg_type(struct bpf_verifier_env *env, u32 regno,
 	if (base_type(arg_type) == ARG_PTR_TO_MEM)
 		type &= ~DYNPTR_TYPE_FLAG_MASK;
 
-	if (meta->func_id == BPF_FUNC_kptr_xchg && type & MEM_ALLOC)
+	if (meta->func_id == BPF_FUNC_kptr_xchg && type_is_alloc(type))
 		type &= ~MEM_ALLOC;
 
 	for (i = 0; i < ARRAY_SIZE(compatible->types); i++) {
-- 
2.34.1