From: Andy Lutomirski <luto@amacapital.net>
To: YiFei Zhu <zhuyifei1999@gmail.com>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>,
containers@lists.linux.dev, bpf <bpf@vger.kernel.org>,
YiFei Zhu <yifeifz2@illinois.edu>,
LSM List <linux-security-module@vger.kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Austin Kuo <hckuo2@illinois.edu>,
Claudio Canella <claudio.canella@iaik.tugraz.at>,
Daniel Borkmann <daniel@iogearbox.net>,
Daniel Gruss <daniel.gruss@iaik.tugraz.at>,
Dimitrios Skarlatos <dskarlat@cs.cmu.edu>,
Giuseppe Scrivano <gscrivan@redhat.com>,
Hubertus Franke <frankeh@us.ibm.com>,
Jann Horn <jannh@google.com>, Jinghao Jia <jinghao7@illinois.edu>,
Josep Torrellas <torrella@illinois.edu>,
Kees Cook <keescook@chromium.org>,
Sargun Dhillon <sargun@sargun.me>, Tianyin Xu <tyxu@illinois.edu>,
Tobin Feldman-Fitzthum <tobin@ibm.com>,
Tom Hromatka <tom.hromatka@oracle.com>,
Will Drewry <wad@chromium.org>
Subject: Re: [RFC PATCH bpf-next seccomp 10/12] seccomp-ebpf: Add ability to read user memory
Date: Thu, 13 May 2021 07:53:15 -0700 [thread overview]
Message-ID: <B541CF0E-3410-4CA3-93E4-670052C5FC11@amacapital.net> (raw)
In-Reply-To: <CABqSeAR9rgARxYGYUVZQgZ0a-wqZxy-qeoVpu495XHxpj0Ku=A@mail.gmail.com>
> On May 12, 2021, at 10:26 PM, YiFei Zhu <zhuyifei1999@gmail.com> wrote:
>
> On Wed, May 12, 2021 at 5:36 PM Alexei Starovoitov
> <alexei.starovoitov@gmail.com> wrote:
>> Typically the verifier does all the checks at load time to avoid
>> run-time overhead during program execution. Then at attach time we
>> check that attach parameters provided at load time match exactly
>> to those at attach time. ifindex, attach_btf_id, etc fall into this category.
>> Doing something similar it should be possible to avoid
>> doing get_dumpable() at run-time.
>
> Do you mean to move the check of dumpable to load time instead of
> runtime? I do not think that makes sense. A process may arbitrarily
> set its dumpable attribute during execution via prctl. A process could
> do set itself to non-dumpable, before interacting with sensitive
> information that would better not be possible to be dumped (eg.
> ssh-agent does this [1]). Therefore, being dumpable at one point in
> time does not indicate anything about whether it stays dumpable at a
> later point in time. Besides, seccomp filters are inherited across
> clone and exec, attaching to many tasks with no option to detach. What
> should the load-time check of task dump-ability be against? The
> current task may only be the tip of an iceburg.
>
> [1] https://github.com/openssh/openssh-portable/blob/2dc328023f60212cd29504fc05d849133ae47355/ssh-agent.c#L1398
>
>
First things first: why are you checking dumpable at all? Once you figure out why and whether it’s needed, you may learn something about what task to check.
I don’t think checking dumpable makes any sense.
next prev parent reply other threads:[~2021-05-13 14:53 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-10 17:22 [RFC PATCH bpf-next seccomp 00/12] eBPF seccomp filters YiFei Zhu
2021-05-10 17:22 ` [RFC PATCH bpf-next seccomp 01/12] seccomp: Move no_new_privs check to after prepare_filter YiFei Zhu
2021-05-10 17:22 ` [RFC PATCH bpf-next seccomp 02/12] bpf, seccomp: Add eBPF filter capabilities YiFei Zhu
2021-05-10 17:22 ` [RFC PATCH bpf-next seccomp 03/12] seccomp, ptrace: Add a mechanism to retrieve attached eBPF seccomp filters YiFei Zhu
2021-05-10 17:22 ` [RFC PATCH bpf-next seccomp 04/12] libbpf: recognize section "seccomp" YiFei Zhu
2021-05-10 17:22 ` [RFC PATCH bpf-next seccomp 05/12] samples/bpf: Add eBPF seccomp sample programs YiFei Zhu
2021-05-10 17:22 ` [RFC PATCH bpf-next seccomp 06/12] lsm: New hook seccomp_extended YiFei Zhu
2021-05-10 17:22 ` [RFC PATCH bpf-next seccomp 07/12] bpf/verifier: allow restricting direct map access YiFei Zhu
2021-05-10 17:22 ` [RFC PATCH bpf-next seccomp 08/12] seccomp-ebpf: restrict filter to almost cBPF if LSM request such YiFei Zhu
2021-05-10 17:22 ` [RFC PATCH bpf-next seccomp 09/12] yama: (concept) restrict seccomp-eBPF with ptrace_scope YiFei Zhu
2021-05-10 17:22 ` [RFC PATCH bpf-next seccomp 10/12] seccomp-ebpf: Add ability to read user memory YiFei Zhu
2021-05-11 2:04 ` Alexei Starovoitov
2021-05-11 7:14 ` YiFei Zhu
2021-05-12 22:36 ` Alexei Starovoitov
2021-05-13 5:26 ` YiFei Zhu
2021-05-13 14:53 ` Andy Lutomirski [this message]
2021-05-13 17:12 ` YiFei Zhu
2021-05-13 17:15 ` Andy Lutomirski
2021-05-10 17:22 ` [RFC PATCH bpf-next seccomp 11/12] bpf/verifier: support NULL-able ptr to BTF ID as helper argument YiFei Zhu
2021-05-10 17:22 ` [RFC PATCH bpf-next seccomp 12/12] seccomp-ebpf: support task storage from BPF-LSM, defaulting to group leader YiFei Zhu
2021-05-11 1:58 ` Alexei Starovoitov
2021-05-11 5:44 ` YiFei Zhu
2021-05-12 21:56 ` Alexei Starovoitov
2021-05-10 17:47 ` [RFC PATCH bpf-next seccomp 00/12] eBPF seccomp filters Andy Lutomirski
2021-05-11 5:21 ` YiFei Zhu
2021-05-15 15:49 ` Andy Lutomirski
2021-05-20 9:05 ` Christian Brauner
[not found] ` <fffbea8189794a8da539f6082af3de8e@DM5PR11MB1692.namprd11.prod.outlook.com>
2021-05-16 8:38 ` Tianyin Xu
2021-05-17 15:40 ` Tycho Andersen
2021-05-17 17:07 ` Sargun Dhillon
[not found] ` <108b4b9c2daa4123805d2b92cf51374b@DM5PR11MB1692.namprd11.prod.outlook.com>
2021-05-20 8:16 ` Tianyin Xu
2021-05-20 8:56 ` Christian Brauner
2021-05-20 9:37 ` Christian Brauner
2021-06-01 19:55 ` Kees Cook
2021-06-09 6:32 ` Jinghao Jia
2021-06-09 6:27 ` Jinghao Jia
[not found] ` <00fe481c572d486289bc88780f48e88f@DM5PR11MB1692.namprd11.prod.outlook.com>
2021-05-20 22:13 ` Tianyin Xu
[not found] ` <eae2a0e5038b41c4af87edcb3d4cdc13@DM5PR11MB1692.namprd11.prod.outlook.com>
2021-05-20 8:22 ` Tianyin Xu
2021-05-24 18:55 ` Sargun Dhillon
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