linux-kernel - Re: [PATCH] bpf: validate bpf_func when BPF

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Message-ID: <CABCJKueLLs7nUFnQ-BHWE3cPJncWACy2tG196n01QPpShUwKEg@mail.gmail.com>
Date:   Wed, 11 Sep 2019 13:29:56 -0700
From:   Sami Tolvanen <samitolvanen@...gle.com>
To:     Yonghong Song <yhs@...com>
Cc:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Kees Cook <keescook@...omium.org>, Martin Lau <kafai@...com>,
        Song Liu <songliubraving@...com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "bpf@...r.kernel.org" <bpf@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Toke Høiland-Jørgensen <toke@...hat.com>,
        Björn Töpel <bjorn.topel@...el.com>
Subject: Re: [PATCH] bpf: validate bpf_func when BPF_JIT is enabled

On Wed, Sep 11, 2019 at 12:43 AM Yonghong Song <yhs@...com> wrote:
> How about this:
>
>         if (!IS_ENABLED(CONFIG_BPF_JIT_ALWAYS_ON) && !prog->jited)
>                 goto out;
>
>         if (unlikely(hdr->magic != BPF_BINARY_HEADER_MAGIC ||
>             !arch_bpf_jit_check_func(prog))) {
>                 WARN(1, "attempt to jump to an invalid address");
>                 return 0;
>         }
> out:
>         return prog->bpf_func(ctx, prog->insnsi);

Sure, that does look cleaner. I'll use this in the next version. Thanks.

Sami