linux-kernel - Re: [PATCH bpf-next 1/2] bpf: Remove bpf_jit

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Thu, 15 Apr 2021 16:49:36 -0700
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Quentin Monnet <quentin@...valent.com>
Cc:     Daniel Borkmann <daniel@...earbox.net>,
        Jianlin Lv <Jianlin.Lv@....com>, bpf <bpf@...r.kernel.org>,
        Jonathan Corbet <corbet@....net>,
        Alexei Starovoitov <ast@...nel.org>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Shubham Bansal <illusionist.neo@...il.com>,
        Russell King <linux@...linux.org.uk>,
        Zi Shen Lim <zlim.lnx@...il.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, paulburton@...nel.org,
        tsbogend@...ha.franken.de,
        "Naveen N . Rao" <naveen.n.rao@...ux.ibm.com>,
        Sandipan Das <sandipan@...ux.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Luke Nelson <luke.r.nels@...il.com>,
        Xi Wang <xi.wang@...il.com>,
        Björn Töpel <bjorn@...nel.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Ilya Leoshkevich <iii@...ux.ibm.com>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        David Ahern <dsahern@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        X86 ML <x86@...nel.org>, "H. Peter Anvin" <hpa@...or.com>,
        Wang YanQing <udknight@...il.com>,
        Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Mahesh Bandewar <maheshb@...gle.com>,
        Simon Horman <horms@...ge.net.au>,
        Nicolas Dichtel <nicolas.dichtel@...nd.com>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Kees Cook <keescook@...omium.org>,
        Tobias Klauser <tklauser@...tanz.ch>, grantseltzer@...il.com,
        Ian Rogers <irogers@...gle.com>,
        "open list:DOCUMENTATION" <linux-doc@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Network Development <netdev@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        linux-mips@...r.kernel.org,
        ppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        linux-riscv <linux-riscv@...ts.infradead.org>,
        linux-s390 <linux-s390@...r.kernel.org>,
        sparclinux@...r.kernel.org, iecedge@...il.com
Subject: Re: [PATCH bpf-next 1/2] bpf: Remove bpf_jit_enable=2 debugging mode

On Thu, Apr 15, 2021 at 8:41 AM Quentin Monnet <quentin@...valent.com> wrote:
>
> 2021-04-15 16:37 UTC+0200 ~ Daniel Borkmann <daniel@...earbox.net>
> > On 4/15/21 11:32 AM, Jianlin Lv wrote:
> >> For debugging JITs, dumping the JITed image to kernel log is discouraged,
> >> "bpftool prog dump jited" is much better way to examine JITed dumps.
> >> This patch get rid of the code related to bpf_jit_enable=2 mode and
> >> update the proc handler of bpf_jit_enable, also added auxiliary
> >> information to explain how to use bpf_jit_disasm tool after this change.
> >>
> >> Signed-off-by: Jianlin Lv <Jianlin.Lv@....com>
>
> Hello,
>
> For what it's worth, I have already seen people dump the JIT image in
> kernel logs in Qemu VMs running with just a busybox, not for kernel
> development, but in a context where buiding/using bpftool was not
> possible.

If building/using bpftool is not possible then majority of selftests won't
be exercised. I don't think such environment is suitable for any kind
of bpf development. Much so for JIT debugging.
While bpf_jit_enable=2 is nothing but the debugging tool for JIT developers.
I'd rather nuke that code instead of carrying it from kernel to kernel.