linux-kernel - Re: [PATCH v3 17/23] landlock: Log TCP bind and connect denials

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Message-ID: <20250106.ea8aex7jai3O@digikod.net>
Date: Mon, 6 Jan 2025 15:51:39 +0100
From: Mickaël Salaün <mic@...ikod.net>
To: Paul Moore <paul@...l-moore.com>
Cc: Eric Paris <eparis@...hat.com>, 
	Günther Noack <gnoack@...gle.com>, "Serge E . Hallyn" <serge@...lyn.com>, 
	Ben Scarlato <akhna@...gle.com>, Casey Schaufler <casey@...aufler-ca.com>, 
	Charles Zaffery <czaffery@...lox.com>, Francis Laniel <flaniel@...ux.microsoft.com>, 
	James Morris <jmorris@...ei.org>, Jann Horn <jannh@...gle.com>, Jeff Xu <jeffxu@...gle.com>, 
	Jorge Lucangeli Obes <jorgelo@...gle.com>, Kees Cook <kees@...nel.org>, 
	Konstantin Meskhidze <konstantin.meskhidze@...wei.com>, Matt Bobrowski <mattbobrowski@...gle.com>, 
	Mikhail Ivanov <ivanov.mikhail1@...wei-partners.com>, Phil Sutter <phil@....cc>, 
	Praveen K Paladugu <prapal@...ux.microsoft.com>, Robert Salvet <robert.salvet@...lox.com>, 
	Shervin Oloumi <enlightened@...gle.com>, Song Liu <song@...nel.org>, 
	Tahera Fahimi <fahimitahera@...il.com>, audit@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-security-module@...r.kernel.org
Subject: Re: [PATCH v3 17/23] landlock: Log TCP bind and connect denials

On Sat, Jan 04, 2025 at 08:23:52PM -0500, Paul Moore wrote:
> On Nov 22, 2024 =?UTF-8?q?Micka=C3=ABl=20Sala=C3=BCn?= <mic@...ikod.net> wrote:
> > 
> > Add audit support to socket_bind and socket_connect hooks.
> > 
> > Audit event sample:
> > 
> >   type=LL_DENY [...]: domain=195ba459b blockers=net_connect_tcp daddr=127.0.0.1 dest=80
> 
> The destination address and port is already captured in the SOCKADDR
> record for bind() and connect(), please don't duplicate it here.

This does not show up when a connect or bind is denied.  I guess this is
because move_addr_to_kernel() is called at syscall entry when there is
no context, whereas a Landlock denial is created after that.  For this
to work, users would have to log a list of syscalls, which would not be
usable (nor reliably maintainable) for most users.  I guess this might
be different with io_uring too.

SELinux and other LSMs log it this way, which makes sense to me.

> 
> > Cc: Günther Noack <gnoack@...gle.com>
> > Cc: Konstantin Meskhidze <konstantin.meskhidze@...wei.com>
> > Cc: Mikhail Ivanov <ivanov.mikhail1@...wei-partners.com>
> > Signed-off-by: Mickaël Salaün <mic@...ikod.net>
> > Link: https://lore.kernel.org/r/20241122143353.59367-18-mic@digikod.net
> > ---
> > Changes since v2:
> > - Remove potentially superfluous IPv6 saddr log, spotted by Francis
> >   Laniel.
> > - Cosmetic improvements.
> > ---
> >  security/landlock/audit.c | 12 +++++++++
> >  security/landlock/audit.h |  1 +
> >  security/landlock/net.c   | 51 ++++++++++++++++++++++++++++++++++++---
> >  3 files changed, 60 insertions(+), 4 deletions(-)
> 
> --
> paul-moore.com