From patchwork Fri Jan 31 16:30:35 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= X-Patchwork-Id: 13955520 Received: from smtp-bc0d.mail.infomaniak.ch (smtp-bc0d.mail.infomaniak.ch [45.157.188.13]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E840082488 for ; Fri, 31 Jan 2025 16:31:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.157.188.13 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738341083; cv=none; b=AydorgNCn8uw5WZ5TBFQa0ums5poRNI12OHPFI9+o9G8dqtAc/kZIqucHaY7m5hN581dgPoKV/+7HZnsXoLFrG7d678NbcwejBkyum0n1oFcie79llzYri3JwaVGU3RRMZM2Uov0yFFbfioXFRwC0rfJV0C4J9GDoVJlJZuxHDQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738341083; c=relaxed/simple; bh=AMCt9P6JkUkWuDlFOAwTYwzzwCm+3MqgVgNFik0QwFU=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version:Content-Type; b=i6NEqv8kHQGVDCOiZJGqhRRSaCVFxc9v8hFWkWUOPW9ffwaTQKe7NGBtD3OJsrJ5zjspm+YwiLk8bJzGDbeN/PTXlGYiTRoPwlTEyQQZziSsoXsSqFJxS+X9eW8V5PAVqfGb0gk1j1GSZe7CCwnG4TxbxXJsWcGOOzZBk8br2OE= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=digikod.net; spf=pass smtp.mailfrom=digikod.net; dkim=pass (1024-bit key) header.d=digikod.net header.i=@digikod.net header.b=yreGICnE; arc=none smtp.client-ip=45.157.188.13 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=digikod.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=digikod.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=digikod.net header.i=@digikod.net header.b="yreGICnE" Received: from smtp-4-0000.mail.infomaniak.ch (smtp-4-0000.mail.infomaniak.ch [10.7.10.107]) by smtp-4-3000.mail.infomaniak.ch (Postfix) with ESMTPS id 4Yl1bx1bbJz1gm; Fri, 31 Jan 2025 17:31:09 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=digikod.net; s=20191114; t=1738341069; bh=dvwAlD2qxUygC9tykM8ERL17YCg24jVBE/X4ecph5ks=; h=From:To:Cc:Subject:Date:From; b=yreGICnEccaYZchGm2dUyVnvEfZDCljZlzEuBAmyiOsofUFGa3mkfuzfDAdVLmEQI BEVMJKaBsRjLSQmHxlQxTYbS+1mrpRKyOgDgaqZKj7ODOarS4ePhyGJyWcN+Hx2U3H Po/sCi5uJvQWw0VUK5Mosy837+5yitE1YOVKlEZA= Received: from unknown by smtp-4-0000.mail.infomaniak.ch (Postfix) with ESMTPA id 4Yl1bt6x7KzXSY; Fri, 31 Jan 2025 17:31:06 +0100 (CET) From: =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= To: Eric Paris , Paul Moore , =?utf-8?q?G=C3=BCnther_Noack?= , "Serge E . Hallyn" Cc: =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= , Ben Scarlato , Casey Schaufler , Charles Zaffery , Daniel Burgener , Francis Laniel , James Morris , Jann Horn , Jeff Xu , Jorge Lucangeli Obes , Kees Cook , Konstantin Meskhidze , Matt Bobrowski , Mikhail Ivanov , Phil Sutter , Praveen K Paladugu , Robert Salvet , Shervin Oloumi , Song Liu , Tahera Fahimi , Tyler Hicks , audit@vger.kernel.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org Subject: [PATCH v5 00/24] Landlock audit support Date: Fri, 31 Jan 2025 17:30:35 +0100 Message-ID: <20250131163059.1139617-1-mic@digikod.net> Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Infomaniak-Routing: alpha Hi, This patch series adds audit support to Landlock. Logging denied requests is useful for different use cases: - sysadmins: to look for users' issues, - security experts: to detect attack attempts, - power users: to understand denials, - developers: to ease sandboxing support and get feedback from users. Because of its unprivileged nature, Landlock can compose standalone security policies (i.e. domains). To make logs useful, they need to contain the most relevant Landlock domain that denied an action, and the reason of such denial. This translates to the latest nested domain and the related blockers: missing access rights or other kind of restrictions. # Changes from previous version Remove the AUDIT_EXE_LANDLOCK_DENY audit rule and add 2 new landlock_restrict_self(2) flags to filter Landlock audit events, which makes 3 flags: - LANDLOCK_RESTRICT_SELF_QUIET: do not log any denied access because of this new domain. - LANDLOCK_RESTRICT_SELF_QUIET_DESCENDENTS: do not log denied access from child domains. - LANDLOCK_RESTRICT_SELF_LOG_CROSS_EXEC: log denied access for processes resulting from an execve(2), which is not the case by default anymore. One patch was merged in mainline: 7ccbe076d987 ("lsm: Only build lsm_audit.c if CONFIG_SECURITY and CONFIG_AUDIT are set"). # Design Log records are created for any denied actions caused by a Landlock policy, which means that a well-sandboxed applications should not log anything except for unattended access requests that might be the result of attacks or bugs. However, sandbox tools creating restricted environments could lead to abundant log entries because the sandboxed processes may not be aware of the related restrictions. To avoid log spam, the landlock_restrict_self(2) syscall gets a new LANDLOCK_RESTRICT_SELF_QUIET flag to not log denials related to this specific domain. Except for well-understood exceptions, this flag should not be set. Indeed, applications sandboxing themselves should only try to bypass their own sandbox if they are compromised, which should ring a bell thanks to log events. When an action is denied, the related Landlock domain ID is specified. If this domain was not previously described in a log record, one is created. This record contains the domain ID, its creation time, and informations about the process that enforced the restriction (at the time of the call to landlock_restrict_self): PID, UID, executable path, and name (comm). This new approach also brings building blocks for an upcoming unprivileged introspection interface. The unique Landlock IDs will be useful to tie audit log entries to running processes, and to get properties of the related Landlock domains. This will replace the previously logged ruleset properties. # Samples Here are two examples of log events (see serial numbers): $ LL_FS_RO=/ LL_FS_RW=/ LL_SCOPED=s LL_FORCE_LOG=1 ./sandboxer kill 1 type=LANDLOCK_ACCESS msg=audit(1729738800.268:30): domain=1a6fdc66f blockers=scope.signal opid=1 ocomm="systemd" type=LANDLOCK_DOMAIN msg=audit(1729738800.268:30): domain=1a6fdc66f status=allocated mode=enforcing pid=286 uid=0 exe="/root/sandboxer" comm="sandboxer" type=SYSCALL msg=audit(1729738800.268:30): arch=c000003e syscall=62 success=no exit=-1 [..] ppid=272 pid=286 auid=0 uid=0 gid=0 [...] comm="kill" [...] type=PROCTITLE msg=audit(1729738800.268:30): proctitle=6B696C6C0031 type=LANDLOCK_DOMAIN msg=audit(1729738800.324:31): domain=1a6fdc66f status=deallocated denials=1 $ LL_FS_RO=/ LL_FS_RW=/tmp LL_FORCE_LOG=1 ./sandboxer sh -c "echo > /etc/passwd" type=LANDLOCK_ACCESS msg=audit(1729738800.221:33): domain=1a6fdc679 blockers=fs.write_file path="/dev/tty" dev="devtmpfs" ino=9 type=LANDLOCK_DOMAIN msg=audit(1729738800.221:33): domain=1a6fdc679 status=allocated mode=enforcing pid=289 uid=0 exe="/root/sandboxer" comm="sandboxer" type=SYSCALL msg=audit(1729738800.221:33): arch=c000003e syscall=257 success=no exit=-13 [...] ppid=272 pid=289 auid=0 uid=0 gid=0 [...] comm="sh" [...] type=PROCTITLE msg=audit(1729738800.221:33): proctitle=7368002D63006563686F203E202F6574632F706173737764 type=LANDLOCK_ACCESS msg=audit(1729738800.221:34): domain=1a6fdc679 blockers=fs.write_file path="/etc/passwd" dev="vda2" ino=143821 type=SYSCALL msg=audit(1729738800.221:34): arch=c000003e syscall=257 success=no exit=-13 [...] ppid=272 pid=289 auid=0 uid=0 gid=0 [...] comm="sh" [...] type=PROCTITLE msg=audit(1729738800.221:34): proctitle=7368002D63006563686F203E202F6574632F706173737764 type=LANDLOCK_DOMAIN msg=audit(1729738800.261:35): domain=1a6fdc679 status=deallocated denials=2 # Future changes I'll add more tests to check each kind of denied access. # Previous versions v4: https://lore.kernel.org/r/20250108154338.1129069-1-mic@digikod.net v3: https://lore.kernel.org/r/20241122143353.59367-1-mic@digikod.net v2: https://lore.kernel.org/r/20241022161009.982584-1-mic@digikod.net v1: https://lore.kernel.org/r/20230921061641.273654-1-mic@digikod.net Regards, Mickaël Salaün (24): lsm: Add audit_log_lsm_data() helper landlock: Add unique ID generator landlock: Move domain hierarchy management landlock: Prepare to use credential instead of domain for filesystem landlock: Prepare to use credential instead of domain for network landlock: Prepare to use credential instead of domain for scope landlock: Prepare to use credential instead of domain for fowner landlock: Identify domain execution crossing landlock: Add AUDIT_LANDLOCK_ACCESS and log ptrace denials landlock: Add AUDIT_LANDLOCK_DOMAIN and log domain status landlock: Log mount-related denials landlock: Log file-related denials landlock: Log truncate and IOCTL denials landlock: Log TCP bind and connect denials landlock: Log scoped denials landlock: Add LANDLOCK_RESTRICT_SELF_QUIET landlock: Add LANDLOCK_RESTRICT_SELF_QUIET_SUBDOMAINS landlock: Add LANDLOCK_RESTRICT_SELF_LOG_CROSS_EXEC samples/landlock: Enable users to log sandbox denials selftests/landlock: Extend tests for landlock_restrict_self()'s flags selftests/landlock: Add tests for audit and LANDLOCK_RESTRICT_SELF_QUIET selftests/landlock: Test audit with restrict flags selftests/landlock: Add audit tests for ptrace landlock: Add audit documentation Documentation/admin-guide/LSM/index.rst | 1 + Documentation/admin-guide/LSM/landlock.rst | 157 ++++++ Documentation/security/landlock.rst | 7 + Documentation/userspace-api/landlock.rst | 9 +- MAINTAINERS | 1 + include/linux/lsm_audit.h | 8 + include/uapi/linux/audit.h | 4 +- include/uapi/linux/landlock.h | 31 ++ samples/landlock/sandboxer.c | 37 +- security/landlock/.kunitconfig | 2 + security/landlock/Makefile | 5 + security/landlock/access.h | 23 + security/landlock/audit.c | 513 ++++++++++++++++++ security/landlock/audit.h | 77 +++ security/landlock/cred.c | 26 +- security/landlock/cred.h | 65 +++ security/landlock/domain.c | 264 +++++++++ security/landlock/domain.h | 158 ++++++ security/landlock/fs.c | 279 ++++++++-- security/landlock/fs.h | 21 +- security/landlock/id.c | 249 +++++++++ security/landlock/id.h | 25 + security/landlock/limits.h | 4 + security/landlock/net.c | 74 ++- security/landlock/ruleset.c | 33 +- security/landlock/ruleset.h | 47 +- security/landlock/setup.c | 2 + security/landlock/syscalls.c | 50 +- security/landlock/task.c | 232 ++++++-- security/lsm_audit.c | 27 +- tools/testing/kunit/configs/all_tests.config | 2 + tools/testing/selftests/landlock/Makefile | 6 +- tools/testing/selftests/landlock/audit.h | 358 ++++++++++++ tools/testing/selftests/landlock/audit_test.c | 425 +++++++++++++++ tools/testing/selftests/landlock/base_test.c | 43 +- tools/testing/selftests/landlock/common.h | 3 + tools/testing/selftests/landlock/config | 1 + .../testing/selftests/landlock/ptrace_test.c | 67 ++- .../selftests/landlock/wait-pipe-sandbox.c | 131 +++++ 39 files changed, 3244 insertions(+), 223 deletions(-) create mode 100644 Documentation/admin-guide/LSM/landlock.rst create mode 100644 security/landlock/audit.c create mode 100644 security/landlock/audit.h create mode 100644 security/landlock/domain.c create mode 100644 security/landlock/domain.h create mode 100644 security/landlock/id.c create mode 100644 security/landlock/id.h create mode 100644 tools/testing/selftests/landlock/audit.h create mode 100644 tools/testing/selftests/landlock/audit_test.c create mode 100644 tools/testing/selftests/landlock/wait-pipe-sandbox.c base-commit: 69e858e0b8b2ea07759e995aa383e8780d9d140c