linux-kernel - Re: [PATCH 13/23] bpf: rework the compat kernel probe handling

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Message-ID: <CAEf4BzZCp3w9YB0Hg1yyfXFTTCv_Kvi2Xc5RXm7DU2kgm31EUg@mail.gmail.com>
Date:   Thu, 21 May 2020 15:10:42 -0700
From:   Andrii Nakryiko <andrii.nakryiko@...il.com>
To:     Christoph Hellwig <hch@....de>
Cc:     x86@...nel.org, Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-parisc@...r.kernel.org, linux-um@...ts.infradead.org,
        Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        linux-mm@...ck.org, open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 13/23] bpf: rework the compat kernel probe handling

On Thu, May 21, 2020 at 8:26 AM Christoph Hellwig <hch@....de> wrote:
>
> Instead of using the dangerous probe_kernel_read and strncpy_from_unsafe
> helpers, rework the compat probes to check if an address is a kernel or
> userspace one, and then use the low-level kernel or user probe helper
> shared by the proper kernel and user probe helpers.  This slightly
> changes behavior as the compat probe on a user address doesn't check
> the lockdown flags, just as the pure user probes do.
>
> Signed-off-by: Christoph Hellwig <hch@....de>
> ---

Looks good, thanks.

Acked-by: Andrii Nakryiko <andriin@...com>

>  kernel/trace/bpf_trace.c | 109 ++++++++++++++++++++++++---------------
>  1 file changed, 67 insertions(+), 42 deletions(-)
>

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