Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <20230406004018.1439952-1-drosen@google.com> <20230406004018.1439952-2-drosen@google.com>
 <CAEf4BzbyX3i6k5eL6D-5enU+u58nVn_fK28zNBJ4w_Vm-+RiMQ@mail.gmail.com>
 <CAADnVQ+jQG95kVqkajr=zz2-vs24XedEXcBgSx29oAjqUsFn2g@mail.gmail.com> <CA+PiJmST4WUH061KaxJ4kRL=fqy3X6+Wgb2E2rrLT5OYjUzxfQ@mail.gmail.com>
In-Reply-To: <CA+PiJmST4WUH061KaxJ4kRL=fqy3X6+Wgb2E2rrLT5OYjUzxfQ@mail.gmail.com>
From:   Andrii Nakryiko <andrii.nakryiko@gmail.com>
Date:   Wed, 3 May 2023 11:39:32 -0700
Message-ID: <CAEf4Bza3ONHzV0OPu2q17g7Z6w4PD8hMAmjP6ov-hKstt7r55A@mail.gmail.com>
Subject: Re: [PATCH 1/3] bpf: verifier: Accept dynptr mem as mem in helpers
To:     Daniel Rosenberg <drosen@google.com>
Cc:     Alexei Starovoitov <alexei.starovoitov@gmail.com>,
        Joanne Koong <joannelkoong@gmail.com>,
        bpf <bpf@vger.kernel.org>, 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>,
        Mykola Lysenko <mykolal@fb.com>,
        LKML <linux-kernel@vger.kernel.org>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@vger.kernel.org>,
        Android Kernel Team <kernel-team@android.com>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

On Mon, May 1, 2023 at 6:12=E2=80=AFPM Daniel Rosenberg <drosen@google.com>=
 wrote:
>
> On Thu, Apr 6, 2023 at 3:13=E2=80=AFPM Alexei Starovoitov
> <alexei.starovoitov@gmail.com> wrote:
> >
> > +1
> > All of the DYNPTR_TYPE_FLAG_MASK flags cannot appear in type =3D=3D reg=
->type
> > here.
> > They are either dynamic flags inside bpf_dynptr_kern->size
> > or in arg_type.
> > Like in bpf_dynptr_from_mem_proto.
>
> Looking at this a bit more, I believe this is to enforce packet
> restrictions for DYNPTR_TYPE_SKB and DYNPTR_TYPE_XDP. When a helper
> function alters a packet, dynptr slices of it are invalidated. If I
> remove that annotation entirely, then the invalid_data_slice family of
> tests fail. bpf_dynptr_from_mem_proto is fine since that's just local
> dynptrs, which don't have any extra limitations.


Ah, ok, thanks for investigating!