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From: Ingo Molnar <mingo-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
To: Alexei Starovoitov <ast-uqk4Ao+rVK5Wk0Htik3J/w@public.gmane.org>
Cc: Daniel Borkmann <daniel-FeC+5ew28dpmcu3hnIyYJQ@public.gmane.org>,
	"David S. Miller" <davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>,
	Andy Lutomirski <luto-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org>,
	Hannes Frederic Sowa
	<hannes-tFNcAqjVMyqKXQKiL6tip0B+6BGkLq7r@public.gmane.org>,
	Eric Dumazet <edumazet-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
	Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>,
	linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH net-next 1/2] bpf: enable non-root eBPF programs
Date: Tue, 6 Oct 2015 09:13:47 +0200	[thread overview]
Message-ID: <20151006071347.GB14093@gmail.com> (raw)
In-Reply-To: <56131B1F.80002-uqk4Ao+rVK5Wk0Htik3J/w@public.gmane.org>


* Alexei Starovoitov <ast-uqk4Ao+rVK5Wk0Htik3J/w@public.gmane.org> wrote:

> On 10/5/15 3:14 PM, Daniel Borkmann wrote:
> >One scenario that comes to mind ... what happens when there are kernel
> >pointers stored in skb->cb[] (either from the current layer or an old
> >one from a different layer that the skb went through previously, but
> >which did not get overwritten)?
> >
> >Socket filters could read a portion of skb->cb[] also when unprived and
> >leak that out through maps. I think the verifier doesn't catch that,
> >right?
> 
> grrr. indeed. previous layer before sk_filter() can leave junk in there.

Could this be solved by activating zeroing/sanitizing of this data if there's an 
active BPF function around that can access that socket?

Thanks,

	Ingo

WARNING: multiple messages have this Message-ID (diff)
From: Ingo Molnar <mingo@kernel.org>
To: Alexei Starovoitov <ast@plumgrid.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>,
	"David S. Miller" <davem@davemloft.net>,
	Andy Lutomirski <luto@amacapital.net>,
	Hannes Frederic Sowa <hannes@stressinduktion.org>,
	Eric Dumazet <edumazet@google.com>,
	Kees Cook <keescook@chromium.org>,
	linux-api@vger.kernel.org, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH net-next 1/2] bpf: enable non-root eBPF programs
Date: Tue, 6 Oct 2015 09:13:47 +0200	[thread overview]
Message-ID: <20151006071347.GB14093@gmail.com> (raw)
In-Reply-To: <56131B1F.80002@plumgrid.com>


* Alexei Starovoitov <ast@plumgrid.com> wrote:

> On 10/5/15 3:14 PM, Daniel Borkmann wrote:
> >One scenario that comes to mind ... what happens when there are kernel
> >pointers stored in skb->cb[] (either from the current layer or an old
> >one from a different layer that the skb went through previously, but
> >which did not get overwritten)?
> >
> >Socket filters could read a portion of skb->cb[] also when unprived and
> >leak that out through maps. I think the verifier doesn't catch that,
> >right?
> 
> grrr. indeed. previous layer before sk_filter() can leave junk in there.

Could this be solved by activating zeroing/sanitizing of this data if there's an 
active BPF function around that can access that socket?

Thanks,

	Ingo

  parent reply	other threads:[~2015-10-06  7:13 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-10-05 20:48 [PATCH net-next 0/2] bpf: unprivileged Alexei Starovoitov
2015-10-05 20:48 ` [PATCH net-next 1/2] bpf: enable non-root eBPF programs Alexei Starovoitov
     [not found]   ` <1444078101-29060-2-git-send-email-ast-uqk4Ao+rVK5Wk0Htik3J/w@public.gmane.org>
2015-10-05 21:00     ` Kees Cook
2015-10-05 21:00       ` Kees Cook
2015-10-05 21:12       ` Alexei Starovoitov
     [not found]         ` <5612E7C4.1010306-uqk4Ao+rVK5Wk0Htik3J/w@public.gmane.org>
2015-10-05 21:16           ` Andy Lutomirski
2015-10-05 21:16             ` Andy Lutomirski
2015-10-05 21:32             ` Alexei Starovoitov
2015-10-05 22:02         ` Kees Cook
2015-10-06  0:28           ` Alexei Starovoitov
2015-10-08  2:29     ` Alexei Starovoitov
2015-10-08  2:29       ` Alexei Starovoitov
2015-10-05 22:14   ` Daniel Borkmann
     [not found]     ` <5612F639.2050305-FeC+5ew28dpmcu3hnIyYJQ@public.gmane.org>
2015-10-06  0:51       ` Alexei Starovoitov
2015-10-06  0:51         ` Alexei Starovoitov
     [not found]         ` <56131B1F.80002-uqk4Ao+rVK5Wk0Htik3J/w@public.gmane.org>
2015-10-06  7:13           ` Ingo Molnar [this message]
2015-10-06  7:13             ` Ingo Molnar
2015-10-06  8:05             ` Daniel Borkmann
2015-10-06  8:20               ` Ingo Molnar
     [not found]                 ` <20151006082048.GA18287-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2015-10-06  8:39                   ` Daniel Borkmann
2015-10-06  8:39                     ` Daniel Borkmann
     [not found]                     ` <561388D1.30406-FeC+5ew28dpmcu3hnIyYJQ@public.gmane.org>
2015-10-06 17:50                       ` Alexei Starovoitov
2015-10-06 17:50                         ` Alexei Starovoitov
2015-10-06 17:56                         ` Eric Dumazet
     [not found]                           ` <1444154160.9555.5.camel-XN9IlZ5yJG9HTL0Zs8A6p/gx64E7kk8eUsxypvmhUTTZJqsBc5GL+g@public.gmane.org>
2015-10-06 18:05                             ` Andy Lutomirski
2015-10-06 18:05                               ` Andy Lutomirski
2015-10-07  6:05                               ` Ingo Molnar
2015-10-06 19:26                           ` Alexei Starovoitov
     [not found]                         ` <561409EC.5050005-uqk4Ao+rVK5Wk0Htik3J/w@public.gmane.org>
2015-10-06 18:03                           ` Daniel Borkmann
2015-10-06 18:03                             ` Daniel Borkmann
2015-10-06 12:45           ` Daniel Borkmann
2015-10-06 12:45             ` Daniel Borkmann
2015-10-07 21:20             ` Alexei Starovoitov
     [not found]               ` <56158CAF.9030209-uqk4Ao+rVK5Wk0Htik3J/w@public.gmane.org>
2015-10-07 22:07                 ` Daniel Borkmann
2015-10-07 22:07                   ` Daniel Borkmann
2015-10-07 22:22                   ` Kees Cook
2015-10-07 23:49                     ` Alexei Starovoitov
     [not found]                       ` <5615AF92.50402-uqk4Ao+rVK5Wk0Htik3J/w@public.gmane.org>
2015-10-08  6:21                         ` Ingo Molnar
2015-10-08  6:21                           ` Ingo Molnar
2015-10-08  6:30                           ` Alexei Starovoitov
2015-10-08 17:42                       ` Kees Cook
2015-10-05 20:48 ` [PATCH net-next 2/2] bpf: charge user for creation of BPF maps and programs Alexei Starovoitov

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