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Message-ID: <58078CE5.50200@iogearbox.net>
Date: Wed, 19 Oct 2016 17:10:29 +0200
From: Daniel Borkmann <daniel@...earbox.net>
To: Thomas Graf <tgraf@...g.ch>, Mickaël Salaün
<mic@...ikod.net>
CC: linux-kernel@...r.kernel.org, Alexei Starovoitov <ast@...nel.org>,
Andy Lutomirski <luto@...capital.net>,
Arnd Bergmann <arnd@...db.de>, Casey Schaufler <casey@...aufler-ca.com>,
Daniel Mack <daniel@...que.org>,
David Drysdale <drysdale@...gle.com>,
"David S . Miller" <davem@...emloft.net>,
Elena Reshetova <elena.reshetova@...el.com>,
"Eric W . Biederman" <ebiederm@...ssion.com>,
James Morris <james.l.morris@...cle.com>,
Kees Cook <keescook@...omium.org>,
Paul Moore <pmoore@...hat.com>, Sargun Dhillon <sargun@...gun.me>,
"Serge E . Hallyn" <serge@...lyn.com>,
Tejun Heo <tj@...nel.org>, Will Drewry <wad@...omium.org>,
kernel-hardening@...ts.openwall.com, linux-api@...r.kernel.org,
linux-security-module@...r.kernel.org, netdev@...r.kernel.org,
cgroups@...r.kernel.org
Subject: Re: [RFC v3 04/22] bpf: Set register type according to is_valid_access()
On 10/19/2016 04:54 PM, Thomas Graf wrote:
> On 09/14/16 at 09:23am, Mickaël Salaün wrote:
>> This fix a pointer leak when an unprivileged eBPF program read a pointer
>> value from the context. Even if is_valid_access() returns a pointer
>> type, the eBPF verifier replace it with UNKNOWN_VALUE. The register
>> value containing an address is then allowed to leak. Moreover, this
>> prevented unprivileged eBPF programs to use functions with (legitimate)
>> pointer arguments.
>>
>> This bug was not a problem until now because the only unprivileged eBPF
>> program allowed is of type BPF_PROG_TYPE_SOCKET_FILTER and all the types
>> from its context are UNKNOWN_VALUE.
>>
>> Signed-off-by: Mickaël Salaün <mic@...ikod.net>
>> Fixes: 969bf05eb3ce ("bpf: direct packet access")
>> Cc: Alexei Starovoitov <ast@...nel.org>
>> Cc: Daniel Borkmann <daniel@...earbox.net>
>
> Can you post this fix separately? It's valid and needed outside of the
> scope of this series.
Yes, that one was already merged:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=1955351da41caa1dbf4139191358fed84909d64b
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