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Date: Wed, 19 Oct 2016 16:54:20 +0200
From: Thomas Graf <tgraf@...g.ch>
To: 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 Borkmann <daniel@...earbox.net>,
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 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.
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