From: Daniel Rosenberg <drosen@google.com>
To: bpf@vger.kernel.org
Cc: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
John Fastabend <john.fastabend@gmail.com>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <martin.lau@linux.dev>,
Song Liu <song@kernel.org>, Yonghong Song <yhs@fb.com>,
KP Singh <kpsingh@kernel.org>,
Stanislav Fomichev <sdf@google.com>, Hao Luo <haoluo@google.com>,
Jiri Olsa <jolsa@kernel.org>, Shuah Khan <shuah@kernel.org>,
Jonathan Corbet <corbet@lwn.net>,
Joanne Koong <joannelkoong@gmail.com>,
Mykola Lysenko <mykolal@fb.com>,
linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
kernel-team@android.com, Daniel Rosenberg <drosen@google.com>
Subject: [PATCH bpf-next v3 4/5] bpf: verifier: Accept dynptr mem as mem in helpers
Date: Fri, 5 May 2023 18:31:33 -0700 [thread overview]
Message-ID: <20230506013134.2492210-5-drosen@google.com> (raw)
In-Reply-To: <20230506013134.2492210-1-drosen@google.com>
This allows using memory retrieved from dynptrs with helper functions
that accept ARG_PTR_TO_MEM. For instance, results from bpf_dynptr_data
can be passed along to bpf_strncmp.
Signed-off-by: Daniel Rosenberg <drosen@google.com>
---
kernel/bpf/verifier.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 7e6bbae9db81..754129d41225 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -7495,12 +7495,16 @@ static int check_reg_type(struct bpf_verifier_env *env, u32 regno,
* ARG_PTR_TO_MEM + MAYBE_NULL is compatible with PTR_TO_MEM and PTR_TO_MEM + MAYBE_NULL,
* but ARG_PTR_TO_MEM is compatible only with PTR_TO_MEM but NOT with PTR_TO_MEM + MAYBE_NULL
*
+ * ARG_PTR_TO_MEM is compatible with PTR_TO_MEM that is tagged with a dynptr type.
+ *
* Therefore we fold these flags depending on the arg_type before comparison.
*/
if (arg_type & MEM_RDONLY)
type &= ~MEM_RDONLY;
if (arg_type & PTR_MAYBE_NULL)
type &= ~PTR_MAYBE_NULL;
+ 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)
type &= ~MEM_ALLOC;
--
2.40.1.521.gf1e218fcd8-goog
next prev parent reply other threads:[~2023-05-06 1:31 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-06 1:31 [PATCH bpf-next v3 0/5] Dynptr Verifier Adjustments Daniel Rosenberg
2023-05-06 1:31 ` [PATCH bpf-next v3 1/5] bpf: Allow NULL buffers in bpf_dynptr_slice(_rw) Daniel Rosenberg
2023-05-06 1:31 ` [PATCH bpf-next v3 2/5] selftests/bpf: Test allowing NULL buffer in dynptr slice Daniel Rosenberg
2023-05-06 1:31 ` [PATCH bpf-next v3 3/5] selftests/bpf: Check overflow in optional buffer Daniel Rosenberg
2023-05-06 1:31 ` Daniel Rosenberg [this message]
2023-05-06 1:31 ` [PATCH bpf-next v3 5/5] selftests/bpf: Accept mem from dynptr in helper funcs Daniel Rosenberg
2023-05-07 0:00 ` [PATCH bpf-next v3 0/5] Dynptr Verifier Adjustments patchwork-bot+netdevbpf
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