From: Jordan Glover <Golden_Miller83@protonmail.ch>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Andy Lutomirski <luto@kernel.org>,
Daniel Colascione <dancol@google.com>,
Song Liu <songliubraving@fb.com>,
Kees Cook <keescook@chromium.org>,
Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Kernel Team <Kernel-team@fb.com>,
Lorenz Bauer <lmb@cloudflare.com>, Jann Horn <jannh@google.com>,
Greg KH <gregkh@linuxfoundation.org>,
Linux API <linux-api@vger.kernel.org>,
LSM List <linux-security-module@vger.kernel.org>
Subject: Re: [PATCH v2 bpf-next 1/4] bpf: unprivileged BPF access via /dev/bpf
Date: Fri, 16 Aug 2019 09:34:45 +0000 [thread overview]
Message-ID: <fkD3fs46a1YnR4lh0tEG-g3tDnDcyZuzji7bAUR9wujPLLl75ZhI8Yk-H1jZpSugO7qChVeCwxAMmxLdeoF2QFS3ZzuYlh7zmeZOmhDJxww=@protonmail.ch> (raw)
In-Reply-To: <20190815230808.2o2qe7a72cwdce2m@ast-mbp.dhcp.thefacebook.com>
On Thursday, August 15, 2019 11:08 PM, Alexei Starovoitov <alexei.starovoitov@gmail.com> wrote:
> On Thu, Aug 15, 2019 at 11:36:43AM -0700, Andy Lutomirski wrote:
>
> > On Thu, Aug 15, 2019 at 10:29 AM Alexei Starovoitov
> > alexei.starovoitov@gmail.com wrote:
> >
> > > On Thu, Aug 15, 2019 at 11:24:54AM +0000, Jordan Glover wrote:
> > >
> > > > systemd --user processes aren't "less privileged". The are COMPLETELY unprivileged.
> > > > Granting them cap_bpf is the same as granting it to every other unprivileged user
> > > > process. Also unprivileged user process can start systemd --user process with any
> > > > command they like.
> > >
> > > systemd itself is trusted. It's the same binary whether it runs as pid=1
> > > or as pid=123. One of the use cases is to make IPAddressDeny= work with --user.
> > > Subset of that feature already works with AmbientCapabilities=CAP_NET_ADMIN.
> > > CAP_BPF is a natural step in the same direction.
> >
> > I have the feeling that we're somehow speaking different languages.
> > What, precisely, do you mean when you say "systemd itself is trusted"?
> > Do you mean "the administrator trusts that the /lib/systemd/systemd
> > binary is not malicious"? Do you mean "the administrator trusts that
> > the running systemd process is not malicious"?
>
> please see
> https://github.com/systemd/systemd/commit/4c1567f29aeb60a6741874bca8a8e3a0bd69ed01
> I'm not advocating for or against this approach.
> Call it 'security hole' or 'better security'.
> There are two categories of people for any feature like this.
> My point that there is a demand to use bpf for non-root and CAP_NET_ADMIN
> level of privileges is acceptable.
> Another option is to relax all of bpf to CAP_NET_ADMIN instead of CAP_SYS_ADMIN.
> But CAP_BPF is clearly better way.
>
Do you realize it's not possible to grant CAP_NET_ADMIN or any other CAP in
"systemd --user" service? Trying to do so will fail with:
"Failed to apply ambient capabilities (before UID change): Operation not permitted"
I think it's crucial to clear that point to avoid confusion in this discussion
where people are talking about different things.
On the other hand running "systemd --system" service with:
User=nobody
AmbientCapabilities=CAP_NET_ADMIN
is perfectly legit and clears some security concerns as only privileged user
can start such service.
Jordan
next prev parent reply other threads:[~2019-08-16 9:34 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20190627201923.2589391-1-songliubraving@fb.com>
[not found] ` <20190627201923.2589391-2-songliubraving@fb.com>
[not found] ` <21894f45-70d8-dfca-8c02-044f776c5e05@kernel.org>
[not found] ` <3C595328-3ABE-4421-9772-8D41094A4F57@fb.com>
[not found] ` <CALCETrWBnH4Q43POU8cQ7YMjb9LioK28FDEQf7aHZbdf1eBZWg@mail.gmail.com>
[not found] ` <0DE7F23E-9CD2-4F03-82B5-835506B59056@fb.com>
[not found] ` <CALCETrWBWbNFJvsTCeUchu3BZJ3SH3dvtXLUB2EhnPrzFfsLNA@mail.gmail.com>
[not found] ` <201907021115.DCD56BBABB@keescook>
[not found] ` <CALCETrXTta26CTtEDnzvtd03-WOGdXcnsAogP8JjLkcj4-mHvg@mail.gmail.com>
[not found] ` <4A7A225A-6C23-4C0F-9A95-7C6C56B281ED@fb.com>
[not found] ` <CALCETrX2bMnwC6_t4b_G-hzJSfMPrkK4YKs5ebcecv2LJ0rt3w@mail.gmail.com>
[not found] ` <514D5453-0AEE-420F-AEB6-3F4F58C62E7E@fb.com>
[not found] ` <1DE886F3-3982-45DE-B545-67AD6A4871AB@amacapital.net>
[not found] ` <7F51F8B8-CF4C-4D82-AAE1-F0F28951DB7F@fb.com>
[not found] ` <77354A95-4107-41A7-8936-D144F01C3CA4@fb.com>
[not found] ` <369476A8-4CE1-43DA-9239-06437C0384C7@fb.com>
2019-07-30 20:24 ` [PATCH v2 bpf-next 1/4] bpf: unprivileged BPF access via /dev/bpf Andy Lutomirski
2019-07-31 8:10 ` Song Liu
2019-07-31 19:09 ` Andy Lutomirski
2019-08-02 7:21 ` Song Liu
2019-08-04 22:16 ` Andy Lutomirski
2019-08-05 0:08 ` Andy Lutomirski
2019-08-05 5:47 ` Andy Lutomirski
2019-08-05 7:36 ` Song Liu
2019-08-05 17:23 ` Andy Lutomirski
2019-08-05 19:21 ` Alexei Starovoitov
2019-08-05 21:25 ` Andy Lutomirski
2019-08-05 22:21 ` Andy Lutomirski
2019-08-06 1:11 ` Alexei Starovoitov
2019-08-07 5:24 ` Andy Lutomirski
2019-08-07 9:03 ` Lorenz Bauer
2019-08-07 13:52 ` Andy Lutomirski
2019-08-13 21:58 ` Alexei Starovoitov
2019-08-13 22:26 ` Daniel Colascione
2019-08-13 23:24 ` Andy Lutomirski
2019-08-13 23:06 ` Andy Lutomirski
2019-08-14 0:57 ` Alexei Starovoitov
2019-08-14 17:51 ` Andy Lutomirski
2019-08-14 22:05 ` Alexei Starovoitov
2019-08-14 22:30 ` Andy Lutomirski
2019-08-14 23:33 ` Alexei Starovoitov
2019-08-14 23:59 ` Andy Lutomirski
2019-08-15 0:36 ` Alexei Starovoitov
2019-08-15 11:24 ` Jordan Glover
2019-08-15 17:28 ` Alexei Starovoitov
2019-08-15 18:36 ` Andy Lutomirski
2019-08-15 23:08 ` Alexei Starovoitov
2019-08-16 9:34 ` Jordan Glover [this message]
2019-08-16 9:59 ` Thomas Gleixner
2019-08-16 11:33 ` Jordan Glover
2019-08-16 19:52 ` Alexei Starovoitov
2019-08-16 20:28 ` Thomas Gleixner
2019-08-17 15:02 ` Alexei Starovoitov
2019-08-17 15:44 ` Andy Lutomirski
2019-08-19 9:15 ` Thomas Gleixner
2019-08-19 17:27 ` Alexei Starovoitov
2019-08-19 17:38 ` Andy Lutomirski
2019-08-15 18:43 ` Jordan Glover
2019-08-15 19:46 ` Kees Cook
2019-08-15 23:46 ` Alexei Starovoitov
2019-08-16 0:54 ` Andy Lutomirski
2019-08-16 5:56 ` Song Liu
2019-08-16 21:45 ` Alexei Starovoitov
2019-08-16 22:22 ` Christian Brauner
2019-08-17 15:08 ` Alexei Starovoitov
2019-08-17 15:16 ` Christian Brauner
2019-08-17 15:36 ` Alexei Starovoitov
2019-08-17 15:42 ` Christian Brauner
2019-08-22 14:17 ` Daniel Borkmann
2019-08-22 15:16 ` Andy Lutomirski
2019-08-22 15:17 ` RFC: very rough draft of a bpf permission model Andy Lutomirski
2019-08-22 23:26 ` Alexei Starovoitov
2019-08-23 23:09 ` Andy Lutomirski
2019-08-26 22:36 ` Alexei Starovoitov
2019-08-27 0:05 ` Andy Lutomirski
2019-08-27 0:34 ` Alexei Starovoitov
2019-08-22 22:48 ` [PATCH v2 bpf-next 1/4] bpf: unprivileged BPF access via /dev/bpf Alexei Starovoitov
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