From patchwork Fri Jun 26 22:38:51 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tyler Hicks X-Patchwork-Id: 11629047 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 2E580618 for ; Fri, 26 Jun 2020 22:39:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1593220B1F for ; Fri, 26 Jun 2020 22:39:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="lSxdc4Ro" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726388AbgFZWjh (ORCPT ); Fri, 26 Jun 2020 18:39:37 -0400 Received: from linux.microsoft.com ([13.77.154.182]:37808 "EHLO linux.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725909AbgFZWje (ORCPT ); Fri, 26 Jun 2020 18:39:34 -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 C0F4A20B4905; Fri, 26 Jun 2020 15:39:32 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com C0F4A20B4905 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1593211173; bh=MNYV62VxHGPBvdC3jd7a3aa0rJsIPisLZWq2XIgStSk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=lSxdc4Ro05Xoqs25RSxd+xCJxSmaWQdWNTZ7r9KgBg9Hc886B4bZarIJq7tmBu9eU Lz1NcXBHNX+lWHWbvP8xG/wB8cprMk7RHrjCFkt+soUies0J86wxNaeLZGnjutn6/n xQKdJb/N+IW+shxO+A5fPFm+9D3Z+g67hQPyNDwQ= 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 Subject: [PATCH v2 02/11] ima: Free the entire rule when deleting a list of rules Date: Fri, 26 Jun 2020 17:38:51 -0500 Message-Id: <20200626223900.253615-3-tyhicks@linux.microsoft.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200626223900.253615-1-tyhicks@linux.microsoft.com> References: <20200626223900.253615-1-tyhicks@linux.microsoft.com> MIME-Version: 1.0 Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org Create a function, ima_free_rule(), to free all memory associated with an ima_rule_entry. Use the new function to fix memory leaks of allocated ima_rule_entry members, such as .fsname and .keyrings, when deleting a list of rules. Make the existing ima_lsm_free_rule() function specific to the LSM audit rule array of an ima_rule_entry and require that callers make an additional call to kfree to free the ima_rule_entry itself. This fixes a memory leak seen when loading by a valid rule that contains an additional piece of allocated memory, such as an fsname, followed by an invalid rule that triggers a policy load failure: # echo -e "dont_measure fsname=securityfs\nbad syntax" > \ /sys/kernel/security/ima/policy -bash: echo: write error: Invalid argument # echo scan > /sys/kernel/debug/kmemleak # cat /sys/kernel/debug/kmemleak unreferenced object 0xffff9bab67ca12c0 (size 16): comm "bash", pid 684, jiffies 4295212803 (age 252.344s) hex dump (first 16 bytes): 73 65 63 75 72 69 74 79 66 73 00 6b 6b 6b 6b a5 securityfs.kkkk. backtrace: [<00000000adc80b1b>] kstrdup+0x2e/0x60 [<00000000d504cb0d>] ima_parse_add_rule+0x7d4/0x1020 [<00000000444825ac>] ima_write_policy+0xab/0x1d0 [<000000002b7f0d6c>] vfs_write+0xde/0x1d0 [<0000000096feedcf>] ksys_write+0x68/0xe0 [<0000000052b544a2>] do_syscall_64+0x56/0xa0 [<000000007ead1ba7>] entry_SYSCALL_64_after_hwframe+0x44/0xa9 Fixes: f1b08bbcbdaf ("ima: define a new policy condition based on the filesystem name") Fixes: 2b60c0ecedf8 ("IMA: Read keyrings= option from the IMA policy") Signed-off-by: Tyler Hicks --- * v2 - Collapsed patch #2 from v1 of this series, into this patch. This patch now introduces ima_free_rule(). - Existing callers of ima_lsm_free_rule() are doing so to free rules after a successful or failed ima_lsm_copy_rule() and those callers continue to directly call ima_lsm_copy_rule() rather than doing explicit reference ownership and calling ima_free_rule(). - The kfree(entry) of ima_lsm_free_rule() was removed from that function to make it focused on freeing the LSM references. Direct callers of ima_lsm_free_rule() must now call kfree(entry) after ima_lsm_free_rule(). - A comment was added in ima_lsm_update_rule() to clarify why ima_free_rule() isn't being used. security/integrity/ima/ima_policy.c | 29 ++++++++++++++++++++++++----- 1 file changed, 24 insertions(+), 5 deletions(-) diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c index d7c268c2b0ce..bf00b966e87f 100644 --- a/security/integrity/ima/ima_policy.c +++ b/security/integrity/ima/ima_policy.c @@ -261,6 +261,21 @@ static void ima_lsm_free_rule(struct ima_rule_entry *entry) security_filter_rule_free(entry->lsm[i].rule); kfree(entry->lsm[i].args_p); } +} + +static void ima_free_rule(struct ima_rule_entry *entry) +{ + if (!entry) + return; + + /* + * entry->template->fields may be allocated in ima_parse_rule() but that + * reference is owned by the corresponding ima_template_desc element in + * the defined_templates list and cannot be freed here + */ + kfree(entry->fsname); + kfree(entry->keyrings); + ima_lsm_free_rule(entry); kfree(entry); } @@ -302,6 +317,7 @@ static struct ima_rule_entry *ima_lsm_copy_rule(struct ima_rule_entry *entry) out_err: ima_lsm_free_rule(nentry); + kfree(nentry); return NULL; } @@ -315,7 +331,14 @@ static int ima_lsm_update_rule(struct ima_rule_entry *entry) list_replace_rcu(&entry->list, &nentry->list); synchronize_rcu(); + /* + * ima_lsm_copy_rule() shallow copied all references, except for the + * LSM references, from entry to nentry so we only want to free the LSM + * references and the entry itself. All other memory refrences will now + * be owned by nentry. + */ ima_lsm_free_rule(entry); + kfree(entry); return 0; } @@ -1402,15 +1425,11 @@ ssize_t ima_parse_add_rule(char *rule) void ima_delete_rules(void) { struct ima_rule_entry *entry, *tmp; - int i; temp_ima_appraise = 0; list_for_each_entry_safe(entry, tmp, &ima_temp_rules, list) { - for (i = 0; i < MAX_LSM_RULES; i++) - kfree(entry->lsm[i].args_p); - list_del(&entry->list); - kfree(entry); + ima_free_rule(entry); } }