From patchwork Tue Jun 23 00:32:24 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tyler Hicks X-Patchwork-Id: 11619455 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id CEEAE6C1 for ; Tue, 23 Jun 2020 00:34:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B5BE420720 for ; Tue, 23 Jun 2020 00:34:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="o4Hmh6p1" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731487AbgFWAeG (ORCPT ); Mon, 22 Jun 2020 20:34:06 -0400 Received: from linux.microsoft.com ([13.77.154.182]:47316 "EHLO linux.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731467AbgFWAeE (ORCPT ); Mon, 22 Jun 2020 20:34:04 -0400 Received: from sequoia.work.tihix.com (162-237-133-238.lightspeed.rcsntx.sbcglobal.net [162.237.133.238]) by linux.microsoft.com (Postfix) with ESMTPSA id 3690520B7192; Mon, 22 Jun 2020 17:34:02 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 3690520B7192 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1592872443; bh=5SUV1Yb368pVxUvao6vZUdFkJ4ebo8QZjbCUMhuzizE=; h=From:To:Cc:Subject:Date:From; b=o4Hmh6p1DIStUoojjTzdpaNqn8kVFzYIQ4+6unQbTrE52s0v0rA4BrMM3kaZE3Htn 5eYTkXweSirwCJnuG8gC6OlPQKapvZGgp3napsAKOTVHqg9AMp8H0L9Mk80sKuMj3n re3DYgBWSwNAddSW9SliDwN1qCp1gjcus2zF3A0o= From: Tyler Hicks To: Mimi Zohar , Dmitry Kasatkin Cc: James Morris , "Serge E . Hallyn" , Lakshmi Ramasubramanian , Prakhar Srivastava , linux-kernel@vger.kernel.org, linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, Janne Karhunen , Eric Biederman , kexec@lists.infradead.org Subject: [PATCH 00/12] ima: Fix rule parsing bugs and extend KEXEC_CMDLINE rule support Date: Mon, 22 Jun 2020 19:32:24 -0500 Message-Id: <20200623003236.830149-1-tyhicks@linux.microsoft.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: This series ultimately extends the supported IMA rule conditionals for the KEXEC_CMDLINE hook function. As of today, there's an imbalance in IMA language conditional support for KEXEC_CMDLINE rules in comparison to KEXEC_KERNEL_CHECK and KEXEC_INITRAMFS_CHECK rules. The KEXEC_CMDLINE rules do not support *any* conditionals so you cannot have a sequence of rules like this: dont_measure func=KEXEC_KERNEL_CHECK obj_type=foo_t dont_measure func=KEXEC_INITRAMFS_CHECK obj_type=foo_t dont_measure func=KEXEC_CMDLINE obj_type=foo_t measure func=KEXEC_KERNEL_CHECK measure func=KEXEC_INITRAMFS_CHECK measure func=KEXEC_CMDLINE Instead, KEXEC_CMDLINE rules can only be measured or not measured and there's no additional flexibility in today's implementation of the KEXEC_CMDLINE hook function. With this series, the above sequence of rules becomes valid and any calls to kexec_file_load() with a kernel and initramfs inode type of foo_t will not be measured (that includes the kernel cmdline buffer) while all other objects given to a kexec_file_load() syscall will be measured. There's obviously not an inode directly associated with the kernel cmdline buffer but this patch series ties the inode based decision making for KEXEC_CMDLINE to the kernel's inode. I think this will be intuitive to policy authors. While reading IMA code and preparing to make this change, I realized that the buffer based hook functions (KEXEC_CMDLINE and KEY_CHECK) are quite special in comparison to longer standing hook functions. These buffer based hook functions can only support measure actions and there are some restrictions on the conditionals that they support. However, the rule parser isn't enforcing any of those restrictions and IMA policy authors wouldn't have any immediate way of knowing that the policy that they wrote is invalid. For example, the sequence of rules above parses successfully in today's kernel but the "dont_measure func=KEXEC_CMDLINE ..." rule is incorrectly handled in ima_match_rules(). The dont_measure rule is *always* considered to be a match so, surprisingly, no KEXEC_CMDLINE measurements are made. While making the rule parser more strict, I realized that the parser does not correctly free all of the allocated memory associated with an ima_rule_entry when going down some error paths. Invalid policy loaded by the policy administrator could result in small memory leaks. I envision patches 1-7 going to stable. The series is ordered in a way that has all the fixes up front, followed by cleanups, followed by the feature patch. The breakdown of patches looks like so: Memory leak fixes: 1-4 Parser strictness fixes: 5-7 Code cleanups made possible by the fixes: 8-11 Extend KEXEC_CMDLINE rule support: 12 Perhaps the most logical ordering for code review is: 1, 2, 3, 4, 8, 9, 5, 6, 7, 10, 11, 12 If you'd like me to re-order or split up the series, just let me know. Thanks for considering these patches! Tyler Tyler Hicks (12): ima: Have the LSM free its audit rule ima: Create a function to free a rule entry ima: Free the entire rule when deleting a list of rules ima: Free the entire rule if it fails to parse ima: Fail rule parsing when buffer hook functions have an invalid action ima: Fail rule parsing when the KEXEC_CMDLINE hook is combined with an invalid cond ima: Fail rule parsing when the KEY_CHECK hook is combined with an invalid cond ima: Shallow copy the args_p member of ima_rule_entry.lsm elements ima: Use correct type for the args_p member of ima_rule_entry.lsm elements ima: Move validation of the keyrings conditional into ima_validate_rule() ima: Use the common function to detect LSM conditionals in a rule ima: Support additional conditionals in the KEXEC_CMDLINE hook function include/linux/ima.h | 4 +- kernel/kexec_file.c | 2 +- security/integrity/ima/ima.h | 9 +- security/integrity/ima/ima_api.c | 2 +- security/integrity/ima/ima_appraise.c | 2 +- security/integrity/ima/ima_asymmetric_keys.c | 2 +- security/integrity/ima/ima_main.c | 24 ++- security/integrity/ima/ima_policy.c | 159 ++++++++++++++----- security/integrity/ima/ima_queue_keys.c | 2 +- 9 files changed, 148 insertions(+), 58 deletions(-)