linux-kernel - Re: [PATCH bpf-next v3 0/4] bpf: verifier: use target program's type for access verifications

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Message-ID: <e88056b2-8c88-b4d3-7a23-3da4f0499ad4@fb.com>
Date:   Tue, 25 Aug 2020 17:10:23 -0700
From:   Yonghong Song <yhs@...com>
To:     Udip Pant <udippant@...com>, Alexei Starovoitov <ast@...nel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>,
        Andrii Nakryiko <andriin@...com>,
        "David S . Miller" <davem@...emloft.net>
CC:     <netdev@...r.kernel.org>, <bpf@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH bpf-next v3 0/4] bpf: verifier: use target program's type
 for access verifications



On 8/25/20 4:19 PM, Udip Pant wrote:
> This patch series adds changes in verifier to make decisions such as granting
> of read / write access or enforcement of return code status based on
> the program type of the target program while using dynamic program
> extension (of type BPF_PROG_TYPE_EXT).
> 
> The BPF_PROG_TYPE_EXT type can be used to extend types such as XDP, SKB
> and others. Since the BPF_PROG_TYPE_EXT program type on itself is just a
> placeholder for those, we need this extended check for those extended
> programs to actually work with proper access, while using this option.
> 
> Patch #1 includes changes in the verifier.
> Patch #2 adds selftests to verify write access on a packet for a valid
> extension program type
> Patch #3 adds selftests to verify proper check for the return code
> Patch #4 adds selftests to ensure access permissions and restrictions
> for some map types such sockmap.
> 
> Changelogs:
>    v2 -> v3:
>      * more comprehensive resolution of the program type in the verifier
>        based on the target program (and not just for the packet access)
>      * selftests for checking return code and map access
>      * Also moved this patch to 'bpf-next' from 'bpf' tree
>    v1 -> v2:
>      * extraction of the logic to resolve prog type into a separate method
>      * selftests to check for packet access for a valid freplace prog
> 
> Udip Pant (4):
>    bpf: verifier: use target program's type for access verifications
>    selftests/bpf: add test for freplace program with write access
>    selftests/bpf: test for checking return code for the extended prog
>    selftests/bpf: test for map update access from within EXT programs
> 
>   kernel/bpf/verifier.c                         | 32 ++++++---
>   .../selftests/bpf/prog_tests/fexit_bpf2bpf.c  | 68 +++++++++++++++++++
>   .../selftests/bpf/progs/fexit_bpf2bpf.c       | 27 ++++++++
>   .../bpf/progs/freplace_attach_probe.c         | 40 +++++++++++
>   .../bpf/progs/freplace_cls_redirect.c         | 34 ++++++++++
>   .../bpf/progs/freplace_connect_v4_prog.c      | 19 ++++++
>   .../selftests/bpf/progs/test_pkt_access.c     | 20 ++++++
>   7 files changed, 229 insertions(+), 11 deletions(-)
>   create mode 100644 tools/testing/selftests/bpf/progs/freplace_attach_probe.c
>   create mode 100644 tools/testing/selftests/bpf/progs/freplace_cls_redirect.c
>   create mode 100644 tools/testing/selftests/bpf/progs/freplace_connect_v4_prog.c

Thanks. LGTM. Ack for the whole series.
Acked-by: Yonghong Song <yhs@...com>