netdev - Re: [PATCH net] bpf: don't let ldimm64 leak map addresses on unprivileged

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Message-Id: <20170508.150848.820947666682881837.davem@davemloft.net>
Date:   Mon, 08 May 2017 15:08:48 -0400 (EDT)
From:   David Miller <davem@...emloft.net>
To:     daniel@...earbox.net
Cc:     alexei.starovoitov@...il.com, jannh@...gle.com, kafai@...com,
        netdev@...r.kernel.org
Subject: Re: [PATCH net] bpf: don't let ldimm64 leak map addresses on
 unprivileged

From: Daniel Borkmann <daniel@...earbox.net>
Date: Mon,  8 May 2017 00:04:09 +0200

> The patch fixes two things at once:
> 
> 1) It checks the env->allow_ptr_leaks and only prints the map address to
>    the log if we have the privileges to do so, otherwise it just dumps 0
>    as we would when kptr_restrict is enabled on %pK. Given the latter is
>    off by default and not every distro sets it, I don't want to rely on
>    this, hence the 0 by default for unprivileged.
> 
> 2) Printing of ldimm64 in the verifier log is currently broken in that
>    we don't print the full immediate, but only the 32 bit part of the
>    first insn part for ldimm64. Thus, fix this up as well; it's okay to
>    access, since we verified all ldimm64 earlier already (including just
>    constants) through replace_map_fd_with_map_ptr().
> 
> Fixes: cbd357008604 ("bpf: verifier (add ability to receive verification log)")
> Reported-by: Jann Horn <jannh@...gle.com>
> Signed-off-by: Daniel Borkmann <daniel@...earbox.net>

Applied, with second Fixes: tag added, and queued up for -stable.

Thanks.