From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Roberto Sassu <roberto.sassu@huawei.com>
Cc: Djalal Harouni <tixxdz@gmail.com>, KP Singh <kpsingh@kernel.org>,
"corbet@lwn.net" <corbet@lwn.net>,
"viro@zeniv.linux.org.uk" <viro@zeniv.linux.org.uk>,
"ast@kernel.org" <ast@kernel.org>,
"daniel@iogearbox.net" <daniel@iogearbox.net>,
"andrii@kernel.org" <andrii@kernel.org>,
"shuah@kernel.org" <shuah@kernel.org>,
"mcoquelin.stm32@gmail.com" <mcoquelin.stm32@gmail.com>,
"alexandre.torgue@foss.st.com" <alexandre.torgue@foss.st.com>,
"zohar@linux.ibm.com" <zohar@linux.ibm.com>,
"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"bpf@vger.kernel.org" <bpf@vger.kernel.org>,
"linux-kselftest@vger.kernel.org"
<linux-kselftest@vger.kernel.org>,
"linux-stm32@st-md-mailman.stormreply.com"
<linux-stm32@st-md-mailman.stormreply.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-integrity@vger.kernel.org"
<linux-integrity@vger.kernel.org>,
"linux-security-module@vger.kernel.org"
<linux-security-module@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 00/18] bpf: Secure and authenticated preloading of eBPF programs
Date: Mon, 4 Apr 2022 15:49:09 -0700 [thread overview]
Message-ID: <CAADnVQJSso+GSXC-QmNmj0GBPZzxRCRfqAcQbqD-6y0CtMSopQ@mail.gmail.com> (raw)
In-Reply-To: <c2e57f10b62940eba3cfcae996e20e3c@huawei.com>
On Mon, Apr 4, 2022 at 10:21 AM Roberto Sassu <roberto.sassu@huawei.com> wrote:
>
> > From: Djalal Harouni [mailto:tixxdz@gmail.com]
> > Sent: Monday, April 4, 2022 9:45 AM
> > On Sun, Apr 3, 2022 at 5:42 PM KP Singh <kpsingh@kernel.org> wrote:
> > >
> > > On Sat, Apr 2, 2022 at 1:55 AM Alexei Starovoitov
> > > <alexei.starovoitov@gmail.com> wrote:
> > ...
> > > >
> > > > > Pinning
> > > > > them to unreachable inodes intuitively looked the
> > > > > way to go for achieving the stated goal.
> > > >
> > > > We can consider inodes in bpffs that are not unlinkable by root
> > > > in the future, but certainly not for this use case.
> > >
> > > Can this not be already done by adding a BPF_LSM program to the
> > > inode_unlink LSM hook?
> > >
> >
> > Also, beside of the inode_unlink... and out of curiosity: making sysfs/bpffs/
> > readonly after pinning, then using bpf LSM hooks
> > sb_mount|remount|unmount...
> > family combining bpf() LSM hook... isn't this enough to:
> > 1. Restrict who can pin to bpffs without using a full MAC
> > 2. Restrict who can delete or unmount bpf filesystem
> >
> > ?
>
> I'm thinking to implement something like this.
>
> First, I add a new program flag called
> BPF_F_STOP_ONCONFIRM, which causes the ref count
> of the link to increase twice at creation time. In this way,
> user space cannot make the link disappear, unless a
> confirmation is explicitly sent via the bpf() system call.
>
> Another advantage is that other LSMs can decide
> whether or not they allow a program with this flag
> (in the bpf security hook).
>
> This would work regardless of the method used to
> load the eBPF program (user space or kernel space).
>
> Second, I extend the bpf() system call with a new
> subcommand, BPF_LINK_CONFIRM_STOP, which
> decreases the ref count for the link of the programs
> with the BPF_F_STOP_ONCONFIRM flag. I will also
> introduce a new security hook (something like
> security_link_confirm_stop), so that an LSM has the
> opportunity to deny the stop (the bpf security hook
> would not be sufficient to determine exactly for
> which link the confirmation is given, an LSM should
> be able to deny the stop for its own programs).
>
> What do you think?
Hack upon a hack? Makes no sense.
next prev parent reply other threads:[~2022-04-04 23:11 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-28 17:50 [PATCH 00/18] bpf: Secure and authenticated preloading of eBPF programs Roberto Sassu
2022-03-28 17:50 ` [PATCH 01/18] bpf: Export bpf_link_inc() Roberto Sassu
2022-03-28 17:50 ` [PATCH 02/18] bpf-preload: Move bpf_preload.h to include/linux Roberto Sassu
2022-03-28 17:50 ` [PATCH 03/18] bpf-preload: Generalize object pinning from the kernel Roberto Sassu
2022-03-28 17:50 ` [PATCH 04/18] bpf-preload: Export and call bpf_obj_do_pin_kernel() Roberto Sassu
2022-03-28 17:50 ` [PATCH 05/18] bpf-preload: Generate static variables Roberto Sassu
2022-03-29 23:51 ` Andrii Nakryiko
2022-03-30 7:44 ` Roberto Sassu
2022-04-04 0:22 ` Andrii Nakryiko
2022-03-30 15:12 ` Roberto Sassu
2022-03-28 17:50 ` [PATCH 06/18] bpf-preload: Generate free_objs_and_skel() Roberto Sassu
2022-03-28 17:50 ` [PATCH 07/18] bpf-preload: Generate preload() Roberto Sassu
2022-03-28 17:50 ` [PATCH 08/18] bpf-preload: Generate load_skel() Roberto Sassu
2022-03-28 17:50 ` [PATCH 09/18] bpf-preload: Generate code to pin non-internal maps Roberto Sassu
2022-03-28 17:50 ` [PATCH 10/18] bpf-preload: Generate bpf_preload_ops Roberto Sassu
2022-03-28 17:50 ` [PATCH 11/18] bpf-preload: Store multiple bpf_preload_ops structures in a linked list Roberto Sassu
2022-03-28 17:50 ` [PATCH 12/18] bpf-preload: Implement new registration method for preloading eBPF programs Roberto Sassu
2022-03-28 17:50 ` [PATCH 13/18] bpf-preload: Move pinned links and maps to a dedicated directory in bpffs Roberto Sassu
2022-03-28 17:50 ` [PATCH 14/18] bpf-preload: Switch to new preload registration method Roberto Sassu
2022-03-29 2:35 ` kernel test robot
2022-03-29 3:27 ` kernel test robot
2022-03-28 17:50 ` [PATCH 15/18] bpf-preload: Generate code of kernel module to preload Roberto Sassu
2022-03-28 17:50 ` [PATCH 16/18] bpf-preload: Do kernel mount to ensure that pinned objects don't disappear Roberto Sassu
2022-03-29 2:15 ` kernel test robot
2022-03-29 4:08 ` kernel test robot
2022-03-28 17:50 ` [PATCH 17/18] bpf-preload/selftests: Add test for automatic generation of preload methods Roberto Sassu
2022-03-28 17:50 ` [PATCH 18/18] bpf-preload/selftests: Preload a test eBPF program and check pinned objects Roberto Sassu
2022-03-29 23:51 ` [PATCH 00/18] bpf: Secure and authenticated preloading of eBPF programs Andrii Nakryiko
2022-03-30 7:21 ` Roberto Sassu
2022-03-31 2:27 ` Alexei Starovoitov
2022-03-31 8:25 ` Roberto Sassu
2022-04-01 23:55 ` Alexei Starovoitov
2022-04-02 1:03 ` KP Singh
2022-04-04 7:44 ` Djalal Harouni
2022-04-04 17:20 ` Roberto Sassu
2022-04-04 22:49 ` Alexei Starovoitov [this message]
2022-04-05 0:00 ` KP Singh
2022-04-05 13:11 ` [POC][USER SPACE][PATCH] Introduce LSM to protect pinned objects Roberto Sassu
2022-04-05 22:47 ` Casey Schaufler
2022-04-06 6:55 ` Roberto Sassu
2022-04-05 14:49 ` [PATCH 00/18] bpf: Secure and authenticated preloading of eBPF programs Casey Schaufler
2022-04-05 15:29 ` Roberto Sassu
2022-04-05 16:21 ` Casey Schaufler
2022-04-05 16:37 ` KP Singh
2022-04-04 17:41 ` Roberto Sassu
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