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=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT 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 8D71AC433E0 for ; Tue, 30 Mar 2021 20:58:51 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id D037661584 for ; Tue, 30 Mar 2021 20:58:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D037661584 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=chromium.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-21088-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 5351 invoked by uid 550); 30 Mar 2021 20:58:09 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Received: (qmail 5250 invoked from network); 30 Mar 2021 20:58:08 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=uk0/1LocoDticB91SF6FsgWpOKPsEr1Pb6N+E6L28KI=; b=VEbugQSfiOADsXzibGQhy5NOUchekygaO5w+6aKv6mqyA4ZN905sZ3owmH5AiDEAWr y1WGVRmoaiaTXLZw321i7qk6pkHyhNFc2ebrQQ9viIxgTTISjvfl3iT2WLVNayRJuoPG sJuIKeFRY9nWrNFtLzOixlEPRhRvLB5pYBi6Q= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=uk0/1LocoDticB91SF6FsgWpOKPsEr1Pb6N+E6L28KI=; b=K3lQO9k2R+RIxPXZOm9A67y/xmken0wTl71GbpuFGVnnKVcdLj7pzxReDCimn1SUys 74/uCjfLDjdRXkDZrjlZ4rqzI43fla0VYzPjFAfwjNyykFagmKWROn5TIy/OOyHGiuT3 QCKiJ0v0tqN+wrNW+ShBTnp+SD0WD7Buj9ptw0EPwYBDz2r1ETikR6+JnhVwGgH+LX0v WFKxUB0je3UjMPzS1YBMgI3nC8fyTILkzY7sEczhZZE7lOjEwkhlO9r8bD7fRN8f9ua3 gqfYv5OV0t18QrDswGqnespHUxkjw3WfkGE7cuHpQ91lMg0J4KEEtT70VCAqkBSx1rW2 C5Aw== X-Gm-Message-State: AOAM5319UFjtcycEYk9eZND77JHh+fTRlmKp0VG+MAk3SSSqBQM2T1Or DrgiLYZ1vabSvm4eHjucMSmTmw== X-Google-Smtp-Source: ABdhPJyU4QoLUAtSD+TbLRFmZhWwHD39ZMTbzgcT3JSLcSiG1GLO7ZUHccc4rKehrDRN8oWr8gFqDA== X-Received: by 2002:a63:5444:: with SMTP id e4mr38308pgm.426.1617137876539; Tue, 30 Mar 2021 13:57:56 -0700 (PDT) From: Kees Cook To: Thomas Gleixner Cc: Kees Cook , Elena Reshetova , x86@kernel.org, Andy Lutomirski , Peter Zijlstra , Catalin Marinas , Will Deacon , Mark Rutland , Alexander Potapenko , Alexander Popov , Ard Biesheuvel , Jann Horn , Vlastimil Babka , David Hildenbrand , Mike Rapoport , Andrew Morton , Jonathan Corbet , Randy Dunlap , kernel-hardening@lists.openwall.com, linux-hardening@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v8 6/6] lkdtm: Add REPORT_STACK for checking stack offsets Date: Tue, 30 Mar 2021 13:57:50 -0700 Message-Id: <20210330205750.428816-7-keescook@chromium.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210330205750.428816-1-keescook@chromium.org> References: <20210330205750.428816-1-keescook@chromium.org> MIME-Version: 1.0 X-Patch-Hashes: v=1; h=sha256; g=fb815901a1ccc1d9c4ca5c3e3cd3729b7f382fe2; i=b69wRsxT78r/3tM1mGa7N6ME6+rlXyFg15giRWRwPAQ=; m=aFqgiEE+nAZdug79A1F+fVTg9ZceUb0WPE8cbHqssVg=; p=ZQ32/kILkW5AD3nBZHO0VMTp4prIPkm7+DdhCHX8KdA= X-Patch-Sig: m=pgp; i=keescook@chromium.org; s=0x0x8972F4DFDC6DC026; b=iQIzBAABCgAdFiEEpcP2jyKd1g9yPm4TiXL039xtwCYFAmBjkM0ACgkQiXL039xtwCYfLRAAs6I uoWwWDp21BaGNMZo2SuY7bzLTQ4wBsh1OJpZI9l3CnXGSdw3rjz7jQr547uKC02JBkmMzEZ8erZZc OXm9KVlfJUxNAf1Xj1ZCOTuB3x9+E+0QA7hUMrZqjcs42ZBPBNkSPjV9A25U9YqznQ5f+qpoKAWEj hxxEXcX+z7qRe6bJas/EC7OMxjIrCaX9Fzf9HOwub9cZbtwx0dPTxKVeITndj71Nd+oDj/2XxQI+X 9hTzBdUHech+9e7EsTReekwPnRwNq+MAzoYB3JZVfZwT7ewjdvO5Iv6CVMthHmHgut+PjTN00vPS4 OhUYWoQNcsKUhGXXhCoZZ2/MHnjMSsLG8Vpgrb3tQXhiSoeMFXtnamdiasKXt7Jc76LttUOUKyHJo ZHT6pvTFlA8E+uzixb92yFkxiRzqIEGMdMQ3OBJfI2tcnS1KMzsv+Jt1VxL3ySC4aMLFFmM2y1UeI n8OdvXvEabfQwKXEvpIfbAZ6Qm1p7zhujxc9Me7VDJ48cNcSHTtxsNzNXWsEe6PpclfeDU0SglY7l phqtiLzuKHVpdfej4wAJbkaGgOs57NUEso25NbDIc7ZM2syVxWrdxxlP4zgxViiuIq6Yr4W/79kHB 93gnDuL1EJ0D3ib6Nvf+fYfybxPTOR9bKJ+jfn7yAh++prlwwWMuNlPcPXQ0yLfA= Content-Transfer-Encoding: 8bit For validating the stack offset behavior, report the offset from a given process's first seen stack address. A quick way to measure the entropy: for i in $(seq 1 1000); do echo "REPORT_STACK" >/sys/kernel/debug/provoke-crash/DIRECT done offsets=$(dmesg | grep 'Stack offset' | cut -d: -f3 | sort | uniq -c | sort -n | wc -l) echo "$(uname -m) bits of stack entropy: $(echo "obase=2; $offsets" | bc | wc -L)" Signed-off-by: Kees Cook --- drivers/misc/lkdtm/bugs.c | 17 +++++++++++++++++ drivers/misc/lkdtm/core.c | 1 + drivers/misc/lkdtm/lkdtm.h | 1 + 3 files changed, 19 insertions(+) diff --git a/drivers/misc/lkdtm/bugs.c b/drivers/misc/lkdtm/bugs.c index 110f5a8538e9..0e8254d0cf0b 100644 --- a/drivers/misc/lkdtm/bugs.c +++ b/drivers/misc/lkdtm/bugs.c @@ -134,6 +134,23 @@ noinline void lkdtm_CORRUPT_STACK_STRONG(void) __lkdtm_CORRUPT_STACK((void *)&data); } +static pid_t stack_pid; +static unsigned long stack_addr; + +void lkdtm_REPORT_STACK(void) +{ + volatile uintptr_t magic; + pid_t pid = task_pid_nr(current); + + if (pid != stack_pid) { + pr_info("Starting stack offset tracking for pid %d\n", pid); + stack_pid = pid; + stack_addr = (uintptr_t)&magic; + } + + pr_info("Stack offset: %d\n", (int)(stack_addr - (uintptr_t)&magic)); +} + void lkdtm_UNALIGNED_LOAD_STORE_WRITE(void) { static u8 data[5] __attribute__((aligned(4))) = {1, 2, 3, 4, 5}; diff --git a/drivers/misc/lkdtm/core.c b/drivers/misc/lkdtm/core.c index b2aff4d87c01..8024b6a5cc7f 100644 --- a/drivers/misc/lkdtm/core.c +++ b/drivers/misc/lkdtm/core.c @@ -110,6 +110,7 @@ static const struct crashtype crashtypes[] = { CRASHTYPE(EXHAUST_STACK), CRASHTYPE(CORRUPT_STACK), CRASHTYPE(CORRUPT_STACK_STRONG), + CRASHTYPE(REPORT_STACK), CRASHTYPE(CORRUPT_LIST_ADD), CRASHTYPE(CORRUPT_LIST_DEL), CRASHTYPE(STACK_GUARD_PAGE_LEADING), diff --git a/drivers/misc/lkdtm/lkdtm.h b/drivers/misc/lkdtm/lkdtm.h index 5ae48c64df24..99f90d3e5e9c 100644 --- a/drivers/misc/lkdtm/lkdtm.h +++ b/drivers/misc/lkdtm/lkdtm.h @@ -17,6 +17,7 @@ void lkdtm_LOOP(void); void lkdtm_EXHAUST_STACK(void); void lkdtm_CORRUPT_STACK(void); void lkdtm_CORRUPT_STACK_STRONG(void); +void lkdtm_REPORT_STACK(void); void lkdtm_UNALIGNED_LOAD_STORE_WRITE(void); void lkdtm_SOFTLOCKUP(void); void lkdtm_HARDLOCKUP(void); -- 2.25.1