From: Alexei Starovoitov <ast@plumgrid•com>
To: Kees Cook <keescook@chromium•org>
Cc: "David S. Miller" <davem@davemloft•net>,
Andy Lutomirski <luto@amacapital•net>,
Ingo Molnar <mingo@kernel•org>,
Hannes Frederic Sowa <hannes@stressinduktion•org>,
Eric Dumazet <edumazet@google•com>,
Daniel Borkmann <daniel@iogearbox•net>,
Linux API <linux-api@vger•kernel.org>,
Network Development <netdev@vger•kernel.org>,
LKML <linux-kernel@vger•kernel.org>
Subject: Re: [PATCH net-next 1/2] bpf: enable non-root eBPF programs
Date: Mon, 5 Oct 2015 17:28:04 -0700 [thread overview]
Message-ID: <56131594.6080801@plumgrid.com> (raw)
In-Reply-To: <CAGXu5jKTDzMXXYJdWdP=b4fABu_b5ifjv88RVMgBkiR=_JUAog@mail.gmail.com>
On 10/5/15 3:02 PM, Kees Cook wrote:
>> the array maps that hold FDs (BPF_MAP_TYPE_PROG_ARRAY and
>> >BPF_MAP_TYPE_PERF_EVENT_ARRAY) don't have lookup/update accessors
>> >from the program side, so programs cannot see or manipulate
>> >those pointers.
>> >For the former only bpf_tail_call() is allowed that takes integer
>> >index and jumps to it. And the latter map accessed with
> Okay, so I can't take a pointer, put it on the stack, take it back any
> part of it as an integer and use it for a tail call?
not quite.
you can store a pointer to stack and read it as 8 byte load back into
another register, but reading <8 byte of it will be rejected.
That's the test:
unpriv: read pointer from stack in small chunks
we obviously want to avoid hiding pointer in integers.
After reading it back from stack as a pointer you cannnot use
this register to pass as index into bpf_tail_call().
That's the test:
unpriv: pass pointer to helper function
please keep shooting everything that comes to mind.
next prev parent reply other threads:[~2015-10-06 0:28 UTC|newest]
Thread overview: 30+ 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
2015-10-05 22:14 ` Daniel Borkmann
[not found] ` <5612F639.2050305-FeC+5ew28dpmcu3hnIyYJQ@public.gmane.org>
2015-10-06 0:51 ` Alexei Starovoitov
[not found] ` <56131B1F.80002-uqk4Ao+rVK5Wk0Htik3J/w@public.gmane.org>
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
[not found] ` <561388D1.30406-FeC+5ew28dpmcu3hnIyYJQ@public.gmane.org>
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
2015-10-07 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 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 22:22 ` 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 6:30 ` Alexei Starovoitov
2015-10-08 17:42 ` Kees Cook
[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 21:12 ` Alexei Starovoitov
[not found] ` <5612E7C4.1010306-uqk4Ao+rVK5Wk0Htik3J/w@public.gmane.org>
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 [this message]
2015-10-08 2:29 ` Alexei Starovoitov
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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