From patchwork Thu Jul 9 00:12:30 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Casey Schaufler X-Patchwork-Id: 11653095 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 9CC4E14DD for ; Thu, 9 Jul 2020 00:38:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 869FA206DF for ; Thu, 9 Jul 2020 00:38:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=yahoo.com header.i=@yahoo.com header.b="j9iv21UP" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726124AbgGIAiu (ORCPT ); Wed, 8 Jul 2020 20:38:50 -0400 Received: from sonic312-28.consmr.mail.bf2.yahoo.com ([74.6.128.90]:42614 "EHLO sonic312-28.consmr.mail.bf2.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726169AbgGIAiu (ORCPT ); Wed, 8 Jul 2020 20:38:50 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.com; s=s2048; t=1594255128; bh=ZLwVrFCXmf99fQBFfDlaFXPCWAaoi49W0k2oTVfsVr8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From:Subject; b=j9iv21UP19mTsuC1Y2wZo7tKuUuAYudBJtQpKTS1BsSTM/GiPEJ2UTTHtNgL0UplxiLPqsejtzE6/2ZyYDr/yy+Y4QveuXDf02QaKyTxAXap06xtnO671M9JcmbjhF6wLA52dxZfiU8iYFuMV/X1fZI3dvJaGQDEQUQylGZ0mnBv4vxz3ux0TyHWdPPdED+1mkupLaKzv4AionWqcUfMZveX0AhL2VE6wlkAjqGpLemSitvJ+Ct3Wv8/Sk2zFdetaXkdr0xJWi9EP7Rx1JMbDQx80G2tPB3vJqBVPA9bqfnfzZZxWvfUFH7D0JGgkG4wOy+xgVDscDCqTalwtOgtLg== X-YMail-OSG: PwNZSIwVM1lXLQL527Ph8xYbk6OnlbQ4k0GZSZ187ZYKWh7jBtlTmIiPV60xpfm wD7barBBOlH_7UMSMuLiZjEZBRPDuEgZWnqND_u.pEU1Sl1gNqR5oNmOkpYEZYsenAp5DFWYF4eh RZ88S4xn.l0NCF2RlbhWhcTP0TghupSE38zXZmyIQQBmh2h_NX53MhxALKUPgq6lPVx5uDq8Ck6N T0PbQmKGsSGu8ZhO_s.J2dlZwhv2xC0zRgFY_wnkX8jeVLj8i8A59LsKIJ9tf5sSXx7PbcjqQriV Yadmy4RB2ytbGbcfi1NA6MEqbCplL3XjcaHq02ILr.uy37rUOFROgy2u0397fcSwgQjuq26o.vQG bi3Ye6V46qDOj6DhTyA4DDqMeRd6WgcJVvhxS7UE1YmXNWV9rZSQ6fAM4slrQi.u5iH3yWpQGtY5 glwI4H6WTtQpNyPzayHsygxI5PiB2dQZZMfeNjJQr1U2DtKzS2EGw1oxOTWU2Fe.PENi.TLIPvur EmSic8wpS_4LkKmQtQPYER1FaQVHD47GQQLmkBK25btObVaHdS74SzLovNliYhShmxtEiXg6kFD0 5THSnxU0GcCeTc_laiaL5UKxwPbluwGbkn4pFQN7nOiL_qpfr.7Vl_S8RH0v14CLZwUBOQX9yup0 gwMX9ncLWmKEflEEnLNdWjWOEHMeadOvQQKNC1LomGBXgmlONUpAzcmWTZZdN6sYYJvFCxVWZUgw C2LbFZLi0DSc6VsRflt91gG5sP94nkUqn6aoFCDeFfRSyq48YN7ZjJSNZbOs9.dUq3xFKzU3XVoo kcScS4qN8Y0EZrBUsX3yNAlQd1Utot4nBPQUxgW64yIREn7RQzi7vNh65hAlZWufm5W0TjvuwNaR oamvYbEnRdIh90VmyfXtz4vVrxF96hIrkSe6RPLnZTIGVn8Mi2FJgocit.cBnFcs08.cqW1K_rmW iCfHhHQqHvl6Ok.UtPvFXfDVNZcaxYmKpyuFrOX7rBY6Jv_iKQ1Tu7Deb5VugcUlsrr8E7LOwAOy _SNxZTmYYTrTerDcZ0M_wObx4UlM6hNl_Vyb8_uosrQDHLaCugVorJcUBRmhmn6McFMGqyO.1IPX KTIohp7NBSlgKGN4poSfzT4yGq4ULmxHAruc_gr2bqZCPvXANDDY7tZ3fCdEDN2OxyXe3Bg5eejs EAXRw96M4BCIK_uAdEZn3aEFwt5sLzfBdWhol0BySWCctn2ZvOuIlP5_g_8Fl0dFedCUGgaPoHUB 6WKY4mDrBL8ImEGkjiCAT2yFVevwt4Zpdw4RhVBrvsMTV.whgU1icCEevxB8eFvId3y5BOF_e2x6 0khcsloZIQSvbsOcoJwzj5lbzcMSBy2hPrA3v8u77VIc3COwCyehemPooyT7N4YX41dNms9ybPct KyK3iiaP.OJh7NdyeltI8h_erw253nNDsIR32Wg-- Received: from sonic.gate.mail.ne1.yahoo.com by sonic312.consmr.mail.bf2.yahoo.com with HTTP; Thu, 9 Jul 2020 00:38:48 +0000 Received: by smtp412.mail.bf1.yahoo.com (VZM Hermes SMTP Server) with ESMTPA ID 943e64489313dc94b871efa014013ab6; Thu, 09 Jul 2020 00:38:43 +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, keescook@chromium.org, john.johansen@canonical.com, penguin-kernel@i-love.sakura.ne.jp, paul@paul-moore.com, sds@tycho.nsa.gov Subject: [PATCH v18 19/23] LSM: Verify LSM display sanity in binder Date: Wed, 8 Jul 2020 17:12:30 -0700 Message-Id: <20200709001234.9719-20-casey@schaufler-ca.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200709001234.9719-1-casey@schaufler-ca.com> References: <20200709001234.9719-1-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 --- security/security.c | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) diff --git a/security/security.c b/security/security.c index d75ad048ffc9..c3fa4b7e9338 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); }