From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, T_DKIMWL_WL_MED,USER_AGENT_GIT,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A5124C28CF6 for ; Fri, 3 Aug 2018 09:36:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3F3402173F for ; Fri, 3 Aug 2018 09:36:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="quK21zVn" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3F3402173F Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732402AbeHCLbl (ORCPT ); Fri, 3 Aug 2018 07:31:41 -0400 Received: from mail-qk0-f201.google.com ([209.85.220.201]:44413 "EHLO mail-qk0-f201.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729913AbeHCLbl (ORCPT ); Fri, 3 Aug 2018 07:31:41 -0400 Received: by mail-qk0-f201.google.com with SMTP id w126-v6so4678705qka.11 for ; Fri, 03 Aug 2018 02:36:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:message-id:mime-version:subject:from:to:cc; bh=gKam9WaYXvtGukQ1JMxYeC89hlAklM7RuKowpz4IWCY=; b=quK21zVntwsOGQrbPbPpyc/0lMQvpBVCDXVlBeGNW21FLAF1trai59UDBYPCE2GG/V DrQ7Wwp4WdeSOZ/jtyUQ/XymWPItKEwzjxI0gCqwTGxtnh8jvfx6ilpNHucV9x0LWmJU VzRhHCalGiCEL9tHGMtgd4YoPWmkXGtlXukYc/nM4QqkrmEJBu3vhSui9BXR+3TEYpQT gJHyPvgkqslr2PR8Em9VAaKoYO/sMGGIp5oNpDTmkI2XSdC/dZXKUetfY3x7vPdpDXZ4 ouGKVPmjp1/2tPuZbJyOdiCRdcWWgY2GdZNGNk72BsqJFUWurqvr1RBvfNYwbtM5SppP xGSw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc; bh=gKam9WaYXvtGukQ1JMxYeC89hlAklM7RuKowpz4IWCY=; b=mGJ/bYRYevE1JgNNhXqivSMlY5u8Y3SIIbNj/Kx6LaIZG8nG5UFahl8cCFUAHqnnID XiKw/Ok+2J4SNp1/QHc8WGaeMmzeQVmZvt3NdzGFSrNnMUFsUDm8XPcCfSVwO18yp5wz o2kWQlxj+yEdj3fXFHtJkDPUGPtr+xUPzRVb+wszns7mKGZPSxgvCo4uO/Zss2gp3q/K 3vxzM+h5qAt36MEev2xtu3nvqgwMqun648MDaIkkWk/AMvwH2F9//EgBQVzPgDgQsPMx PpuUQ7cnF4ERkF5hO32/s2fJMmSFTinUFOzs8RlAqCGptmlkNwzX/QfIe3is5aii82+y U7ig== X-Gm-Message-State: AOUpUlHHJbVRrPNB9kyFPROJ3Jjuaf6jaBOvJPkjjOgKYwvyj/z605xP pwnCeZBeN9yRbHFyCF8sSaYb9j3QcA== X-Google-Smtp-Source: AAOMgpd1k5tas7kSjFbEj5zQSMmxweGcg5QVx7HyvV7lX36a+VEaslYsfPMUd807C87+qsfiIAif5sEZoQ== X-Received: by 2002:ac8:1019:: with SMTP id z25-v6mr3481000qti.14.1533288971594; Fri, 03 Aug 2018 02:36:11 -0700 (PDT) Date: Fri, 3 Aug 2018 11:36:04 +0200 Message-Id: <20180803093604.38254-1-jannh@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.18.0.597.ga71716f1ad-goog Subject: [PATCH] selinux: stricter parsing in mls_context_to_sid() From: Jann Horn To: Paul Moore , Stephen Smalley , Eric Paris , selinux@tycho.nsa.gov, jannh@google.com Cc: James Morris , "Serge E. Hallyn" , linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org mls_context_to_sid incorrectly accepted MLS context strings that are followed by a dash and trailing garbage. Before this change, the following command works: # mount -t tmpfs -o 'context=system_u:object_r:tmp_t:s0-s0:c0-BLAH' \ none mount After this change, it fails with the following error message in dmesg: SELinux: security_context_str_to_sid(system_u:object_r:tmp_t:s0-s0:c0-BLAH) failed for (dev tmpfs, type tmpfs) errno=-22 This is not an important bug; but it is a small quirk that was useful for exploiting a vulnerability in fusermount. This patch does not change the behavior when the policy does not have MLS enabled. Signed-off-by: Jann Horn --- security/selinux/ss/mls.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/security/selinux/ss/mls.c b/security/selinux/ss/mls.c index 39475fb455bc..2c73d612d2ee 100644 --- a/security/selinux/ss/mls.c +++ b/security/selinux/ss/mls.c @@ -344,7 +344,7 @@ int mls_context_to_sid(struct policydb *pol, break; } } - if (delim == '-') { + if (delim == '-' && l == 0) { /* Extract high sensitivity. */ scontextp = p; while (*p && *p != ':') -- 2.18.0.597.ga71716f1ad-goog