From patchwork Fri Jul 24 20:32:22 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Casey Schaufler X-Patchwork-Id: 11684377 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 28DAE13B6 for ; Fri, 24 Jul 2020 20:53:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 11C5C2070B for ; Fri, 24 Jul 2020 20:53:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=yahoo.com header.i=@yahoo.com header.b="QRKfWklV" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726607AbgGXUxo (ORCPT ); Fri, 24 Jul 2020 16:53:44 -0400 Received: from sonic315-22.consmr.mail.bf2.yahoo.com ([74.6.134.196]:45994 "EHLO sonic315-22.consmr.mail.bf2.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726573AbgGXUxo (ORCPT ); Fri, 24 Jul 2020 16:53:44 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.com; s=s2048; t=1595624023; bh=x30nPZLpFPTTON9xwug49FDlGI4IQDIqcRfVllA7iMU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From:Subject; b=QRKfWklVKDKu4Xc/FRdyNU+1wt97tTLfar//634ep5Qt3QOQ5A3Gp4bCOQsKEMSj8hF/E+8SsHrw+lrzYgRxZdHVyuZxTUN5O+aeqZZLOihuzqbT8DIm0pPc4kZwMVjghSfFEtWxbmDOc9yxiCjlHWBXkqDnb2APGwucBnMBGsUu7pK1kNJLPA6pFAoGcUvMU90zXL+8YSA3+ol2JNjp2vFkjl35Me0h5nMDe0UfatENgBW6yizDyKoM39IsRKI3TVCTvwXJYMjSio1DyGBNrow9MlnzE9d4QEc993/BLh2B1rZZZ/5msvafnEksDblnSWhFBxznKn1Agh1jNRE+eA== X-YMail-OSG: ZLVs4.sVM1mKlYaCvqZ4crhUxaVxA_UvdwODwzg40g2jnCr7BdMX0qMVJY1o4zQ LNTQ8Y5ILlctli1TPRLhp5OUHQh3n9EzQBu3ux_gD1WtJs8caiB1cl6CmGh6f91Pp0ZJUkj3TVyD 9ChBPsWiocr.ARWZRS5XsQvGGzFaZ59IcCuWVz4crwi8xv4DjMmqXrHSfCMq4ApwuDiQ2XGYOSD9 kOZ3ahN2wnqNqJwTq5PRYohycpDOurR82w7ikbpBHJTzFmfYsS7XGS_clVXZgPr.59E0wR707eNC .yFC_q7nOHvd51L5tA8vWSalloL4rNVVRMoJzwxpVZRmw6d4u8151I7FcGe7kFh4bWX_QBwQ7zD8 hRzWEz7Iiz149KLzavKWGw8PAPqKg6LYJchtwIjGguYtJs5vgS_X3GCPblRtRp5_1u79E2wc.WAN L0zCOKFfPkbmMxSOA9HxwrEZ4jxYmR8BO1vTGNunJD1bIGtJuGJ3q7n5D2Ihw5F.2p2ZkeKFJHBU LubDKKQGrOjNcXTgaO0Lt5GJCc27WnpCmAbdKyenkvHgdCbBgPlxPexbVYKWCUmMTszmJ6kKQmwQ a8Vzh3363W.pM7a1MfG5EqroSHYJRHcYM0pTlLTOOGV_c30HcEKf7rN6gvDhv5tuN5_HCw6gXF5H GJGjvU2IetqbW_2x.gfoAXmR9.4fWEuy5VwyPS9Ibx8K7Bpvthn2Iu8aET8xHp2DPThDHSS4N0nV uMw4q9MVm1kMub2tNtAkQS8.k5_IT2SZInxclGCvzS.kLXEKMokKZ88Ab7NL9OXcMzwIIrfR.cDx yYD8Hd9337RRXuRF1C4kvhOCxaRqqJuJ0QTAZP.2HfdwlUwew2JY.N1bVleXc.jOTf05zSOtI1Gc MkpnUbbJ6DiZfEBBIDA5EqwEHMZNqcjf75gZVkL.pj8uz_PL3mGLvWbN.qr_iQdAHqrcGLH64pgR 0NO2liB4.dMtFfjRe0OSOqhawsPSUwtVSf1XHcYobswE1gyJFXfJmJw69Hda8JSDPO6qTTJ94l9t 2bhA6MOMMo3daQ.U8DTvJjX0Xu.7tZp64ItEwXk1aoxlE1R7.vGM0LDxziYtwv93T4GAhO7QxPMj iyVe3o1XNzcjpYD0B2y41iE9JNEIp89IIZzMhh2H3A9IC1JFAxiZQ9.wNfjt5TldCWVrchDPE_v3 2hcmwvIjV7VLtGEHlFYULEKR2ik456CMa0sLJZB0W6Wt3fMfZymlnbvFQXwR4z8ZfTEmYdYmNeO2 Ygf5w0p7l63oE8wQnYW2qNGKSM9FNArdt.1Sz3bbrxFw4WeuI0vMIBdrU99zGVqfbcvn.0SOnn.L Dc0Bc9MmBctnflBnlU6keQaKDeU.c1nTMa7LoUm8yPaF0SMPn0hBG35PLFIGLt9_MESx3Iv5h9d1 mNzAALNZXr9o9LEnq7SWRlZhNgMemryHV4pNv6mnc Received: from sonic.gate.mail.ne1.yahoo.com by sonic315.consmr.mail.bf2.yahoo.com with HTTP; Fri, 24 Jul 2020 20:53:43 +0000 Received: by smtp426.mail.ne1.yahoo.com (VZM Hermes SMTP Server) with ESMTPA ID 85512d92fef433638dcf6811c543efee; Fri, 24 Jul 2020 20:53:41 +0000 (UTC) From: Casey Schaufler To: casey.schaufler@intel.com, jmorris@namei.org, linux-security-module@vger.kernel.org, selinux@vger.kernel.org Cc: casey@schaufler-ca.com, linux-audit@redhat.com, keescook@chromium.org, john.johansen@canonical.com, penguin-kernel@i-love.sakura.ne.jp, paul@paul-moore.com, sds@tycho.nsa.gov Subject: [PATCH v19 19/23] LSM: Verify LSM display sanity in binder Date: Fri, 24 Jul 2020 13:32:22 -0700 Message-Id: <20200724203226.16374-20-casey@schaufler-ca.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200724203226.16374-1-casey@schaufler-ca.com> References: <20200724203226.16374-1-casey@schaufler-ca.com> MIME-Version: 1.0 Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: Verify that the tasks on the ends of a binder transaction use the same "display" security module. This prevents confusion of security "contexts". Reviewed-by: Kees Cook Acked-by: Stephen Smalley Signed-off-by: Casey Schaufler Reviewed-by: John Johansen --- security/security.c | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) diff --git a/security/security.c b/security/security.c index ddbaf2073b02..95b48721fb17 100644 --- a/security/security.c +++ b/security/security.c @@ -788,9 +788,38 @@ int security_binder_set_context_mgr(struct task_struct *mgr) return call_int_hook(binder_set_context_mgr, 0, mgr); } +/** + * security_binder_transaction - Binder driver transaction check + * @from: source of the transaction + * @to: destination of the transaction + * + * Verify that the tasks have the same LSM "display", then + * call the security module hooks. + * + * Returns -EINVAL if the displays don't match, or the + * result of the security module checks. + */ int security_binder_transaction(struct task_struct *from, struct task_struct *to) { + int from_display = lsm_task_display(from); + int to_display = lsm_task_display(to); + + /* + * If the display is LSMBLOB_INVALID the first module that has + * an entry is used. This will be in the 0 slot. + * + * This is currently only required if the server has requested + * peer contexts, but it would be unwieldly to have too much of + * the binder driver detail here. + */ + if (from_display == LSMBLOB_INVALID) + from_display = 0; + if (to_display == LSMBLOB_INVALID) + to_display = 0; + if (from_display != to_display) + return -EINVAL; + return call_int_hook(binder_transaction, 0, from, to); }