From patchwork Wed Jun 19 22:23:59 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sean Christopherson X-Patchwork-Id: 11005469 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 7D0B01580 for ; Wed, 19 Jun 2019 22:24:20 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 69F5D286AE for ; Wed, 19 Jun 2019 22:24:20 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 5E3D6288B3; Wed, 19 Jun 2019 22:24:20 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 0A3DD288B4 for ; Wed, 19 Jun 2019 22:24:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730747AbfFSWYS (ORCPT ); Wed, 19 Jun 2019 18:24:18 -0400 Received: from mga18.intel.com ([134.134.136.126]:40157 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730752AbfFSWYR (ORCPT ); Wed, 19 Jun 2019 18:24:17 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga007.jf.intel.com ([10.7.209.58]) by orsmga106.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 19 Jun 2019 15:24:13 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.63,394,1557212400"; d="scan'208";a="150743777" Received: from sjchrist-coffee.jf.intel.com ([10.54.74.36]) by orsmga007.jf.intel.com with ESMTP; 19 Jun 2019 15:24:13 -0700 From: Sean Christopherson To: Jarkko Sakkinen Cc: linux-sgx@vger.kernel.org, linux-security-module@vger.kernel.org, selinux@vger.kernel.org, Bill Roberts , Casey Schaufler , James Morris , Dave Hansen , Cedric Xing , Andy Lutomirski , Jethro Beekman , "Dr . Greg Wettstein" , Stephen Smalley Subject: [RFC PATCH v4 10/12] security/selinux: Add enclave_load() implementation Date: Wed, 19 Jun 2019 15:23:59 -0700 Message-Id: <20190619222401.14942-11-sean.j.christopherson@intel.com> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190619222401.14942-1-sean.j.christopherson@intel.com> References: <20190619222401.14942-1-sean.j.christopherson@intel.com> MIME-Version: 1.0 Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: X-Virus-Scanned: ClamAV using ClamSMTP The goal of selinux_enclave_load() is to provide a facsimile of the existing selinux_file_mprotect() and file_map_prot_check() policies, but tailored to the unique properties of SGX. For example, an enclave page is technically backed by a MAP_SHARED file, but the "file" is essentially shared memory that is never persisted anywhere and also requires execute permissions (for some pages). Enclaves are also less priveleged than normal user code, e.g. SYSCALL instructions #UD if attempted in an enclave. For this reason, add SGX specific permissions instead of reusing existing permissions such as FILE__EXECUTE so that policies can allow running code in an enclave, or allow dynamically loading code in an enclave without having to grant the same capability to normal user code outside of the enclave. Intended use of each permission: - SGX_EXECDIRTY: dynamically load code within the enclave itself - SGX_EXECUNMR: load unmeasured code into the enclave, e.g. Graphene - SGX_EXECANON: load code from anonymous memory (likely Graphene) - SGX_EXECUTE: load an enclave from a file, i.e. normal behavior Note, equivalents to FILE__READ and FILE__WRITE are intentionally never required. Writes to the enclave page are contained to the EPC, i.e. never hit the original file, and read permissions have already been vetted (or the VMA doesn't have PROT_READ, in which case loading the page into the enclave will fail). Signed-off-by: Sean Christopherson --- security/selinux/hooks.c | 55 +++++++++++++++++++++++++++-- security/selinux/include/classmap.h | 5 +-- 2 files changed, 55 insertions(+), 5 deletions(-) diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index fc239e541b62..8a431168e454 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -6727,6 +6727,12 @@ static void selinux_bpf_prog_free(struct bpf_prog_aux *aux) #endif #ifdef CONFIG_INTEL_SGX +static inline int sgx_has_perm(u32 sid, u32 requested) +{ + return avc_has_perm(&selinux_state, sid, sid, + SECCLASS_PROCESS2, requested, NULL); +} + static int selinux_enclave_map(unsigned long prot) { const struct cred *cred = current_cred(); @@ -6736,11 +6742,53 @@ static int selinux_enclave_map(unsigned long prot) WARN_ON_ONCE(!default_noexec); if ((prot & PROT_EXEC) && (prot & PROT_WRITE)) - return avc_has_perm(&selinux_state, sid, sid, - SECCLASS_PROCESS2, PROCESS2__SGX_MAPWX, - NULL); + return sgx_has_perm(sid, PROCESS2__SGX_MAPWX); + return 0; } + +static int selinux_enclave_load(struct vm_area_struct *vma, unsigned long prot, + bool measured) +{ + const struct cred *cred = current_cred(); + u32 sid = cred_sid(cred); + int ret; + + /* SGX is supported only in 64-bit kernels. */ + WARN_ON_ONCE(!default_noexec); + + /* Only executable enclave pages are restricted in any way. */ + if (!(prot & PROT_EXEC)) + return 0; + + /* + * WX at load time only requires EXECDIRTY, e.g. to allow W->X. Actual + * WX mappings require MAPWX (see selinux_enclave_map()). + */ + if (prot & PROT_WRITE) { + ret = sgx_has_perm(sid, PROCESS2__SGX_EXECDIRTY); + if (ret) + goto out; + } + if (!measured) { + ret = sgx_has_perm(sid, PROCESS2__SGX_EXECUNMR); + if (ret) + goto out; + } + + if (!vma->vm_file || IS_PRIVATE(file_inode(vma->vm_file)) || + vma->anon_vma) + /* + * Loading enclave code from an anonymous mapping or from a + * modified private file mapping. + */ + ret = sgx_has_perm(sid, PROCESS2__SGX_EXECANON); + else + /* Loading from a shared or unmodified private file mapping. */ + ret = file_has_perm(cred, vma->vm_file, FILE__SGX_EXECUTE); +out: + return ret; +} #endif struct lsm_blob_sizes selinux_blob_sizes __lsm_ro_after_init = { @@ -6988,6 +7036,7 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = { #ifdef CONFIG_INTEL_SGX LSM_HOOK_INIT(enclave_map, selinux_enclave_map), + LSM_HOOK_INIT(enclave_load, selinux_enclave_load), #endif }; diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h index cfd91e879bdf..baa1757be46a 100644 --- a/security/selinux/include/classmap.h +++ b/security/selinux/include/classmap.h @@ -7,7 +7,7 @@ #define COMMON_FILE_PERMS COMMON_FILE_SOCK_PERMS, "unlink", "link", \ "rename", "execute", "quotaon", "mounton", "audit_access", \ - "open", "execmod" + "open", "execmod", "sgx_execute" #define COMMON_SOCK_PERMS COMMON_FILE_SOCK_PERMS, "bind", "connect", \ "listen", "accept", "getopt", "setopt", "shutdown", "recvfrom", \ @@ -52,7 +52,8 @@ struct security_class_mapping secclass_map[] = { "setsockcreate", "getrlimit", NULL } }, { "process2", { "nnp_transition", "nosuid_transition", - "sgx_mapwx", NULL } }, + "sgx_mapwx", "sgx_execdirty", "sgx_execanon", "sgx_execunmr", + NULL } }, { "system", { "ipc_info", "syslog_read", "syslog_mod", "syslog_console", "module_request", "module_load", NULL } },