From patchwork Thu Jun 25 20:37:01 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 208334 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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, 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 656D0C433E0 for ; Thu, 25 Jun 2020 20:37:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 384E420791 for ; Thu, 25 Jun 2020 20:37:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="Z+l6Gdwk" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2407192AbgFYUhT (ORCPT ); Thu, 25 Jun 2020 16:37:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47432 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2407172AbgFYUhK (ORCPT ); Thu, 25 Jun 2020 16:37:10 -0400 Received: from mail-pf1-x443.google.com (mail-pf1-x443.google.com [IPv6:2607:f8b0:4864:20::443]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 87870C08C5DD for ; Thu, 25 Jun 2020 13:37:10 -0700 (PDT) Received: by mail-pf1-x443.google.com with SMTP id d66so3583318pfd.6 for ; Thu, 25 Jun 2020 13:37:10 -0700 (PDT) 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=SR6ATnMcWEmdUOJ6DbZTTEtf2IDw/YJ2aizPOaBcct0=; b=Z+l6GdwkOd72fTNtHvSsdUn7TKOnxeeN7JeN5GTZo8cfHL+0EpGVAWRA45M5x8Hay9 Lnc4QZpwTo9P293mTeHnToaY5IkuFtejak/F2BeOdZtxIjYSRQA4mtnSRz2SIXFr5yFi 52pcgmThTn6s0zv2SlhZdkY8mLePuLr8ATAGI= 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=SR6ATnMcWEmdUOJ6DbZTTEtf2IDw/YJ2aizPOaBcct0=; b=N3OLcJljcKmcK2bI+nuBCYjh8iOez9w9A03OvXPD45VRPuil3CM36EX1lTMcJyo/8L Eo4GfmP0VoXTEbzVzJOXkZL00wmTurZva7iTRl0SwLMJiAV1SlfUsYeX7sxCbgyU8B8V eVAyaI6WZDWt8yHw3cK8FLsoWoYIXcex5rCbo3AKbYdHamLpUl811meRuXMpiWy7G4M2 T094N4P8HHpLuZn5RzpY/0ysFowG9XY05201g0d0HiHMO2yYT8GwS/D1ZPQKZLgjaefO bmxNe7Zb+bfljIQywWRIwemDA03TyVffERYoQyTbX/lR1oWPpyr2nc7hzmp63JoYKllY +eUA== X-Gm-Message-State: AOAM530dwGmoC6q1mrckFdnkj5diLE/g/DCIvA/uVcPBRfM2RaYXA+xD /ZvSXJ4+MP6HKaG3ZV8TJ9i31w== X-Google-Smtp-Source: ABdhPJytLKN5EnbcLgkC49A0EERl56GpicC+cP7LwdDwUZOYrAuRO1Lb7t+7poX/m1wym1e0HyEqFA== X-Received: by 2002:a62:a218:: with SMTP id m24mr2510238pff.156.1593117430052; Thu, 25 Jun 2020 13:37:10 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id q6sm23903896pff.163.2020.06.25.13.37.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 25 Jun 2020 13:37:07 -0700 (PDT) From: Kees Cook To: Greg Kroah-Hartman Cc: Kees Cook , Prasad Sodagudi , Sami Tolvanen , Amit Daniel Kachhap , Randy Dunlap , Richard Weinberger , linux-kselftest@vger.kernel.org, clang-built-linux@googlegroups.com, linux-kernel@vger.kernel.org Subject: [PATCH drivers/misc v2 1/4] lkdtm: Avoid more compiler optimizations for bad writes Date: Thu, 25 Jun 2020 13:37:01 -0700 Message-Id: <20200625203704.317097-2-keescook@chromium.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200625203704.317097-1-keescook@chromium.org> References: <20200625203704.317097-1-keescook@chromium.org> MIME-Version: 1.0 Sender: linux-kselftest-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org It seems at least Clang is able to throw away writes it knows are destined for read-only memory, which makes things like the WRITE_RO test fail, as the write gets elided. Instead, force the variable to be volatile, and make similar changes through-out other tests in an effort to avoid needing to repeat fixing these kinds of problems. Also includes pr_err() calls in failure paths so that kernel logs are more clear in the failure case. Reported-by: Prasad Sodagudi Suggested-by: Sami Tolvanen Fixes: 9ae113ce5faf ("lkdtm: add tests for additional page permissions") Signed-off-by: Kees Cook --- drivers/misc/lkdtm/bugs.c | 11 +++++------ drivers/misc/lkdtm/perms.c | 22 +++++++++++++++------- drivers/misc/lkdtm/usercopy.c | 7 +++++-- 3 files changed, 25 insertions(+), 15 deletions(-) diff --git a/drivers/misc/lkdtm/bugs.c b/drivers/misc/lkdtm/bugs.c index 736675f0a246..08c70281c380 100644 --- a/drivers/misc/lkdtm/bugs.c +++ b/drivers/misc/lkdtm/bugs.c @@ -118,9 +118,8 @@ noinline void lkdtm_CORRUPT_STACK(void) /* Use default char array length that triggers stack protection. */ char data[8] __aligned(sizeof(void *)); - __lkdtm_CORRUPT_STACK(&data); - - pr_info("Corrupted stack containing char array ...\n"); + pr_info("Corrupting stack containing char array ...\n"); + __lkdtm_CORRUPT_STACK((void *)&data); } /* Same as above but will only get a canary with -fstack-protector-strong */ @@ -131,9 +130,8 @@ noinline void lkdtm_CORRUPT_STACK_STRONG(void) unsigned long *ptr; } data __aligned(sizeof(void *)); - __lkdtm_CORRUPT_STACK(&data); - - pr_info("Corrupted stack containing union ...\n"); + pr_info("Corrupting stack containing union ...\n"); + __lkdtm_CORRUPT_STACK((void *)&data); } void lkdtm_UNALIGNED_LOAD_STORE_WRITE(void) @@ -248,6 +246,7 @@ void lkdtm_ARRAY_BOUNDS(void) kfree(not_checked); kfree(checked); + pr_err("FAIL: survived array bounds overflow!\n"); } void lkdtm_CORRUPT_LIST_ADD(void) diff --git a/drivers/misc/lkdtm/perms.c b/drivers/misc/lkdtm/perms.c index 62f76d506f04..2dede2ef658f 100644 --- a/drivers/misc/lkdtm/perms.c +++ b/drivers/misc/lkdtm/perms.c @@ -57,6 +57,7 @@ static noinline void execute_location(void *dst, bool write) } pr_info("attempting bad execution at %px\n", func); func(); + pr_err("FAIL: func returned\n"); } static void execute_user_location(void *dst) @@ -75,20 +76,22 @@ static void execute_user_location(void *dst) return; pr_info("attempting bad execution at %px\n", func); func(); + pr_err("FAIL: func returned\n"); } void lkdtm_WRITE_RO(void) { - /* Explicitly cast away "const" for the test. */ - unsigned long *ptr = (unsigned long *)&rodata; + /* Explicitly cast away "const" for the test and make volatile. */ + volatile unsigned long *ptr = (unsigned long *)&rodata; pr_info("attempting bad rodata write at %px\n", ptr); *ptr ^= 0xabcd1234; + pr_err("FAIL: survived bad write\n"); } void lkdtm_WRITE_RO_AFTER_INIT(void) { - unsigned long *ptr = &ro_after_init; + volatile unsigned long *ptr = &ro_after_init; /* * Verify we were written to during init. Since an Oops @@ -102,19 +105,21 @@ void lkdtm_WRITE_RO_AFTER_INIT(void) pr_info("attempting bad ro_after_init write at %px\n", ptr); *ptr ^= 0xabcd1234; + pr_err("FAIL: survived bad write\n"); } void lkdtm_WRITE_KERN(void) { size_t size; - unsigned char *ptr; + volatile unsigned char *ptr; size = (unsigned long)do_overwritten - (unsigned long)do_nothing; ptr = (unsigned char *)do_overwritten; pr_info("attempting bad %zu byte write at %px\n", size, ptr); - memcpy(ptr, (unsigned char *)do_nothing, size); + memcpy((void *)ptr, (unsigned char *)do_nothing, size); flush_icache_range((unsigned long)ptr, (unsigned long)(ptr + size)); + pr_err("FAIL: survived bad write\n"); do_overwritten(); } @@ -193,9 +198,11 @@ void lkdtm_ACCESS_USERSPACE(void) pr_info("attempting bad read at %px\n", ptr); tmp = *ptr; tmp += 0xc0dec0de; + pr_err("FAIL: survived bad read\n"); pr_info("attempting bad write at %px\n", ptr); *ptr = tmp; + pr_err("FAIL: survived bad write\n"); vm_munmap(user_addr, PAGE_SIZE); } @@ -203,19 +210,20 @@ void lkdtm_ACCESS_USERSPACE(void) void lkdtm_ACCESS_NULL(void) { unsigned long tmp; - unsigned long *ptr = (unsigned long *)NULL; + volatile unsigned long *ptr = (unsigned long *)NULL; pr_info("attempting bad read at %px\n", ptr); tmp = *ptr; tmp += 0xc0dec0de; + pr_err("FAIL: survived bad read\n"); pr_info("attempting bad write at %px\n", ptr); *ptr = tmp; + pr_err("FAIL: survived bad write\n"); } void __init lkdtm_perms_init(void) { /* Make sure we can write to __ro_after_init values during __init */ ro_after_init |= 0xAA; - } diff --git a/drivers/misc/lkdtm/usercopy.c b/drivers/misc/lkdtm/usercopy.c index e172719dd86d..b833367a45d0 100644 --- a/drivers/misc/lkdtm/usercopy.c +++ b/drivers/misc/lkdtm/usercopy.c @@ -304,19 +304,22 @@ void lkdtm_USERCOPY_KERNEL(void) return; } - pr_info("attempting good copy_to_user from kernel rodata\n"); + pr_info("attempting good copy_to_user from kernel rodata: %px\n", + test_text); if (copy_to_user((void __user *)user_addr, test_text, unconst + sizeof(test_text))) { pr_warn("copy_to_user failed unexpectedly?!\n"); goto free_user; } - pr_info("attempting bad copy_to_user from kernel text\n"); + pr_info("attempting bad copy_to_user from kernel text: %px\n", + vm_mmap); if (copy_to_user((void __user *)user_addr, vm_mmap, unconst + PAGE_SIZE)) { pr_warn("copy_to_user failed, but lacked Oops\n"); goto free_user; } + pr_err("FAIL: survived bad copy_to_user()\n"); free_user: vm_munmap(user_addr, PAGE_SIZE); From patchwork Thu Jun 25 20:37:03 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 208335 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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, 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 CD66CC433E0 for ; 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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id r13sm9278734pfr.181.2020.06.25.13.37.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 25 Jun 2020 13:37:07 -0700 (PDT) From: Kees Cook To: Greg Kroah-Hartman Cc: Kees Cook , Prasad Sodagudi , Sami Tolvanen , Amit Daniel Kachhap , Randy Dunlap , Richard Weinberger , linux-kselftest@vger.kernel.org, clang-built-linux@googlegroups.com, linux-kernel@vger.kernel.org Subject: [PATCH drivers/misc v2 3/4] selftests/lkdtm: Reset WARN_ONCE to avoid false negatives Date: Thu, 25 Jun 2020 13:37:03 -0700 Message-Id: <20200625203704.317097-4-keescook@chromium.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200625203704.317097-1-keescook@chromium.org> References: <20200625203704.317097-1-keescook@chromium.org> MIME-Version: 1.0 Sender: linux-kselftest-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Since we expect to see warnings every time for many tests, just reset the WARN_ONCE flags each time the script runs. Fixes: 46d1a0f03d66 ("selftests/lkdtm: Add tests for LKDTM targets") Signed-off-by: Kees Cook --- tools/testing/selftests/lkdtm/run.sh | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/tools/testing/selftests/lkdtm/run.sh b/tools/testing/selftests/lkdtm/run.sh index ee64ff8df8f4..8383eb89d88a 100755 --- a/tools/testing/selftests/lkdtm/run.sh +++ b/tools/testing/selftests/lkdtm/run.sh @@ -8,6 +8,7 @@ # set -e TRIGGER=/sys/kernel/debug/provoke-crash/DIRECT +CLEAR_ONCE=/sys/kernel/debug/clear_warn_once KSELFTEST_SKIP_TEST=4 # Verify we have LKDTM available in the kernel. @@ -67,6 +68,11 @@ cleanup() { } trap cleanup EXIT +# Reset WARN_ONCE counters so we trip it each time this runs. +if [ -w $CLEAR_ONCE ] ; then + echo 1 > $CLEAR_ONCE +fi + # Save existing dmesg so we can detect new content below dmesg > "$DMESG"