Kernel-hardening archive on lore.kernel.org
 help / color / Atom feed
From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Casey Schaufler <casey@schaufler-ca.com>
Cc: "Mickaël Salaün" <mic@digikod.net>,
	linux-kernel@vger.kernel.org,
	"Alexei Starovoitov" <ast@kernel.org>,
	"Andy Lutomirski" <luto@amacapital.net>,
	"Daniel Borkmann" <daniel@iogearbox.net>,
	"David Drysdale" <drysdale@google.com>,
	"Florent Revest" <revest@chromium.org>,
	"James Morris" <jmorris@namei.org>, "Jann Horn" <jann@thejh.net>,
	"John Johansen" <john.johansen@canonical.com>,
	"Jonathan Corbet" <corbet@lwn.net>,
	"Kees Cook" <keescook@chromium.org>,
	"KP Singh" <kpsingh@chromium.org>,
	"Michael Kerrisk" <mtk.manpages@gmail.com>,
	"Mickaël Salaün" <mickael.salaun@ssi.gouv.fr>,
	"Paul Moore" <paul@paul-moore.com>,
	"Sargun Dhillon" <sargun@sargun.me>,
	"Serge E . Hallyn" <serge@hallyn.com>,
	"Shuah Khan" <shuah@kernel.org>,
	"Stephen Smalley" <sds@tycho.nsa.gov>,
	"Tejun Heo" <tj@kernel.org>,
	"Tetsuo Handa" <penguin-kernel@I-love.SAKURA.ne.jp>,
	"Tycho Andersen" <tycho@tycho.ws>,
	"Will Drewry" <wad@chromium.org>,
	bpf@vger.kernel.org, kernel-hardening@lists.openwall.com,
	linux-api@vger.kernel.org, linux-security-module@vger.kernel.org,
	netdev@vger.kernel.org
Subject: Re: [PATCH bpf-next v13 4/7] landlock: Add ptrace LSM hooks
Date: Tue, 5 Nov 2019 11:31:32 -0800
Message-ID: <20191105193130.qam2eafnmgvrvjwk@ast-mbp.dhcp.thefacebook.com> (raw)
In-Reply-To: <c5c6b433-7e6a-c8f8-f063-e704c3df4cc6@schaufler-ca.com>

On Tue, Nov 05, 2019 at 09:55:42AM -0800, Casey Schaufler wrote:
> On 11/5/2019 9:18 AM, Alexei Starovoitov wrote:
> > On Mon, Nov 04, 2019 at 06:21:43PM +0100, Mickaël Salaün wrote:
> >> Add a first Landlock hook that can be used to enforce a security policy
> >> or to audit some process activities.  For a sandboxing use-case, it is
> >> needed to inform the kernel if a task can legitimately debug another.
> >> ptrace(2) can also be used by an attacker to impersonate another task
> >> and remain undetected while performing malicious activities.
> >>
> >> Using ptrace(2) and related features on a target process can lead to a
> >> privilege escalation.  A sandboxed task must then be able to tell the
> >> kernel if another task is more privileged, via ptrace_may_access().
> >>
> >> Signed-off-by: Mickaël Salaün <mic@digikod.net>
> > ...
> >> +static int check_ptrace(struct landlock_domain *domain,
> >> +		struct task_struct *tracer, struct task_struct *tracee)
> >> +{
> >> +	struct landlock_hook_ctx_ptrace ctx_ptrace = {
> >> +		.prog_ctx = {
> >> +			.tracer = (uintptr_t)tracer,
> >> +			.tracee = (uintptr_t)tracee,
> >> +		},
> >> +	};
> > So you're passing two kernel pointers obfuscated as u64 into bpf program
> > yet claiming that the end goal is to make landlock unprivileged?!
> > The most basic security hole in the tool that is aiming to provide security.
> >
> > I think the only way bpf-based LSM can land is both landlock and KRSI
> > developers work together on a design that solves all use cases. BPF is capable
> > to be a superset of all existing LSMs
> 
> I can't agree with this. Nope. There are many security models
> for which BPF introduces excessive complexity. You don't need
> or want the generality of a general purpose programming language
> to implement Smack or TOMOYO. Or a simple Bell & LaPadula for
> that matter. SELinux? I can't imagine anyone trying to do that
> in eBPF, although I'm willing to be surprised. Being able to
> enforce a policy isn't the only criteria for an LSM. 

what are the other criteria?

> It's got
> to perform well and integrate with the rest of the system. 

what do you mean by that?

> I see many issues with a BPF <-> vfs interface.

There is no such interface today. What do you have in mind?

> the mechanisms needed for the concerns of the day. Ideally,
> we should be able to drop mechanisms when we decide that they
> no longer add value.

Exactly. bpf-based lsm must not add to kernel abi.


  reply index

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-04 17:21 [PATCH bpf-next v13 0/7] Landlock LSM Mickaël Salaün
2019-11-04 17:21 ` [PATCH bpf-next v13 1/7] bpf,landlock: Define an eBPF program type for Landlock hooks Mickaël Salaün
2019-11-04 17:21 ` [PATCH bpf-next v13 2/7] landlock: Add the management of domains Mickaël Salaün
2019-11-04 17:21 ` [PATCH bpf-next v13 3/7] landlock,seccomp: Apply Landlock programs to process hierarchy Mickaël Salaün
2019-11-04 17:21 ` [PATCH bpf-next v13 4/7] landlock: Add ptrace LSM hooks Mickaël Salaün
2019-11-05 17:18   ` Alexei Starovoitov
2019-11-05 17:55     ` Casey Schaufler
2019-11-05 19:31       ` Alexei Starovoitov [this message]
2019-11-05 19:55         ` Casey Schaufler
2019-11-05 21:54           ` Alexei Starovoitov
2019-11-05 22:32             ` Casey Schaufler
2019-11-05 18:01     ` Mickaël Salaün
2019-11-05 19:34       ` Alexei Starovoitov
2019-11-05 22:18         ` Mickaël Salaün
2019-11-06 10:06         ` KP Singh
2019-11-06 16:55           ` Mickaël Salaün
2019-11-06 21:45             ` KP Singh
2019-11-08 14:08               ` Mickaël Salaün
2019-11-08 14:34                 ` Daniel Borkmann
2019-11-08 15:39                   ` Mickaël Salaün
2019-11-08 15:27                 ` KP Singh
2019-11-06 10:15       ` KP Singh
2019-11-06 16:58         ` Mickaël Salaün
2019-11-04 17:21 ` [PATCH bpf-next v13 5/7] bpf,landlock: Add task_landlock_ptrace_ancestor() helper Mickaël Salaün
2019-11-04 17:21 ` [PATCH bpf-next v13 6/7] bpf,landlock: Add tests for the Landlock ptrace program type Mickaël Salaün
2019-11-04 17:21 ` [PATCH bpf-next v13 7/7] landlock: Add user and kernel documentation for Landlock Mickaël Salaün

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20191105193130.qam2eafnmgvrvjwk@ast-mbp.dhcp.thefacebook.com \
    --to=alexei.starovoitov@gmail.com \
    --cc=ast@kernel.org \
    --cc=bpf@vger.kernel.org \
    --cc=casey@schaufler-ca.com \
    --cc=corbet@lwn.net \
    --cc=daniel@iogearbox.net \
    --cc=drysdale@google.com \
    --cc=jann@thejh.net \
    --cc=jmorris@namei.org \
    --cc=john.johansen@canonical.com \
    --cc=keescook@chromium.org \
    --cc=kernel-hardening@lists.openwall.com \
    --cc=kpsingh@chromium.org \
    --cc=linux-api@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-security-module@vger.kernel.org \
    --cc=luto@amacapital.net \
    --cc=mic@digikod.net \
    --cc=mickael.salaun@ssi.gouv.fr \
    --cc=mtk.manpages@gmail.com \
    --cc=netdev@vger.kernel.org \
    --cc=paul@paul-moore.com \
    --cc=penguin-kernel@I-love.SAKURA.ne.jp \
    --cc=revest@chromium.org \
    --cc=sargun@sargun.me \
    --cc=sds@tycho.nsa.gov \
    --cc=serge@hallyn.com \
    --cc=shuah@kernel.org \
    --cc=tj@kernel.org \
    --cc=tycho@tycho.ws \
    --cc=wad@chromium.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Kernel-hardening archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/kernel-hardening/0 kernel-hardening/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 kernel-hardening kernel-hardening/ https://lore.kernel.org/kernel-hardening \
		kernel-hardening@lists.openwall.com
	public-inbox-index kernel-hardening

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/com.openwall.lists.kernel-hardening


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git