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=-13.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 C6712C433E2 for ; Sun, 12 Jul 2020 13:23:15 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id D2BD02068F for ; Sun, 12 Jul 2020 13:23:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D2BD02068F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.ibm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 4B4SC35dLyzDqX6 for ; Sun, 12 Jul 2020 23:23:11 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=linux.ibm.com (client-ip=148.163.158.5; helo=mx0a-001b2d01.pphosted.com; envelope-from=aneesh.kumar@linux.ibm.com; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4B4S8d55mpzDqYC for ; Sun, 12 Jul 2020 23:21:05 +1000 (AEST) Received: from pps.filterd (m0098416.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 06CD24Hh057911; Sun, 12 Jul 2020 09:20:56 -0400 Received: from ppma02dal.us.ibm.com (a.bd.3ea9.ip4.static.sl-reverse.com [169.62.189.10]) by mx0b-001b2d01.pphosted.com with ESMTP id 32771w3vrn-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Sun, 12 Jul 2020 09:20:56 -0400 Received: from pps.filterd (ppma02dal.us.ibm.com [127.0.0.1]) by ppma02dal.us.ibm.com (8.16.0.42/8.16.0.42) with SMTP id 06CDK1Cf020457; Sun, 12 Jul 2020 13:20:55 GMT Received: from b03cxnp08026.gho.boulder.ibm.com (b03cxnp08026.gho.boulder.ibm.com [9.17.130.18]) by ppma02dal.us.ibm.com with ESMTP id 327528kmmn-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Sun, 12 Jul 2020 13:20:55 +0000 Received: from b03ledav003.gho.boulder.ibm.com (b03ledav003.gho.boulder.ibm.com [9.17.130.234]) by b03cxnp08026.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 06CDKpit23462352 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sun, 12 Jul 2020 13:20:51 GMT Received: from b03ledav003.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 330796A051; Sun, 12 Jul 2020 13:20:54 +0000 (GMT) Received: from b03ledav003.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 11D916A047; Sun, 12 Jul 2020 13:20:51 +0000 (GMT) Received: from skywalker.ibmuc.com (unknown [9.79.221.252]) by b03ledav003.gho.boulder.ibm.com (Postfix) with ESMTP; Sun, 12 Jul 2020 13:20:51 +0000 (GMT) From: "Aneesh Kumar K.V" To: linuxppc-dev@lists.ozlabs.org, mpe@ellerman.id.au Subject: [PATCH] powerpc/book3s64/pkeys: Fix pkey_access_permitted w.r.t execute disable pkey Date: Sun, 12 Jul 2020 18:50:47 +0530 Message-Id: <20200712132047.1038594-1-aneesh.kumar@linux.ibm.com> X-Mailer: git-send-email 2.26.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235, 18.0.687 definitions=2020-07-12_04:2020-07-10, 2020-07-12 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 mlxscore=0 mlxlogscore=358 impostorscore=0 malwarescore=0 suspectscore=2 adultscore=0 clxscore=1015 bulkscore=0 phishscore=0 lowpriorityscore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2007120100 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "Aneesh Kumar K.V" , linuxram@us.ibm.com, Sandipan Das Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Even if the IAMR value deny the execute access, current kernel return true w.r.t pkey_access_permitted() for execute permission check if the AMR read pkey bit is cleared. This results in repeated page fault loop with a test like below. #define _GNU_SOURCE #include #include #include #include #include #include #include #include #include #include #ifdef SYS_pkey_mprotect #undef SYS_pkey_mprotect #endif #ifdef SYS_pkey_alloc #undef SYS_pkey_alloc #endif #ifdef SYS_pkey_free #undef SYS_pkey_free #endif #undef PKEY_DISABLE_EXECUTE #define PKEY_DISABLE_EXECUTE 0x4 #define SYS_pkey_mprotect 386 #define SYS_pkey_alloc 384 #define SYS_pkey_free 385 #define PPC_INST_NOP 0x60000000 #define PPC_INST_BLR 0x4e800020 #define PROT_RWX (PROT_READ | PROT_WRITE | PROT_EXEC) static int sys_pkey_mprotect(void *addr, size_t len, int prot, int pkey) { return syscall(SYS_pkey_mprotect, addr, len, prot, pkey); } static int sys_pkey_alloc(unsigned long flags, unsigned long access_rights) { return syscall(SYS_pkey_alloc, flags, access_rights); } static int sys_pkey_free(int pkey) { return syscall(SYS_pkey_free, pkey); } static void do_execute(void *region) { /* jump to region */ asm volatile( "mtctr %0;" "bctrl" : : "r"(region) : "ctr", "lr"); } static void do_protect(void *region) { size_t pgsize; int i, pkey; pgsize = getpagesize(); pkey = sys_pkey_alloc(0, PKEY_DISABLE_EXECUTE); assert (pkey > 0); /* perform mprotect */ assert(!sys_pkey_mprotect(region, pgsize, PROT_RWX, pkey)); do_execute(region); /* free pkey */ assert(!sys_pkey_free(pkey)); } int main(int argc, char **argv) { size_t pgsize, numinsns; unsigned int *region; int i; /* allocate memory region to protect */ pgsize = getpagesize(); region = memalign(pgsize, pgsize); assert(region != NULL); assert(!mprotect(region, pgsize, PROT_RWX)); /* fill page with NOPs with a BLR at the end */ numinsns = pgsize / sizeof(region[0]); for (i = 0; i < numinsns - 1; i++) region[i] = PPC_INST_NOP; region[i] = PPC_INST_BLR; do_protect(region); return EXIT_SUCCESS; } Fixes: f2407ef3ba22 ("powerpc: helper to validate key-access permissions of a pte") Reported-by: Sandipan Das Signed-off-by: Aneesh Kumar K.V --- arch/powerpc/mm/book3s64/pkeys.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/arch/powerpc/mm/book3s64/pkeys.c b/arch/powerpc/mm/book3s64/pkeys.c index ca5fcb4bff32..d174106bab67 100644 --- a/arch/powerpc/mm/book3s64/pkeys.c +++ b/arch/powerpc/mm/book3s64/pkeys.c @@ -354,12 +354,14 @@ static bool pkey_access_permitted(int pkey, bool write, bool execute) u64 amr; pkey_shift = pkeyshift(pkey); - if (execute && !(read_iamr() & (IAMR_EX_BIT << pkey_shift))) - return true; + if (execute) + return !(read_iamr() & (IAMR_EX_BIT << pkey_shift)); + + amr = read_amr(); + if (write) + return !(amr & (AMR_WR_BIT << pkey_shift)); - amr = read_amr(); /* Delay reading amr until absolutely needed */ - return ((!write && !(amr & (AMR_RD_BIT << pkey_shift))) || - (write && !(amr & (AMR_WR_BIT << pkey_shift)))); + return !(amr & (AMR_RD_BIT << pkey_shift)); } bool arch_pte_access_permitted(u64 pte, bool write, bool execute) -- 2.26.2