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=-15.7 required=3.0 tests=BAYES_00,DKIM_ADSP_ALL, DKIM_INVALID,DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 42401C56202 for ; Wed, 18 Nov 2020 11:07:55 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 922FF223C7 for ; Wed, 18 Nov 2020 11:07:54 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=privacyrequired.com header.i=@privacyrequired.com header.b="AFtoFdEn" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 922FF223C7 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=privacyrequired.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 224356B006E; Wed, 18 Nov 2020 06:07:54 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 1ACD46B0070; Wed, 18 Nov 2020 06:07:54 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 076766B0071; Wed, 18 Nov 2020 06:07:54 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0003.hostedemail.com [216.40.44.3]) by kanga.kvack.org (Postfix) with ESMTP id CA5B26B006E for ; Wed, 18 Nov 2020 06:07:53 -0500 (EST) Received: from smtpin30.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 70E7B1EE6 for ; Wed, 18 Nov 2020 11:07:53 +0000 (UTC) X-FDA: 77497264026.30.pest98_0d12dde27339 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin30.hostedemail.com (Postfix) with ESMTP id 4670F180B3C85 for ; Wed, 18 Nov 2020 11:07:53 +0000 (UTC) X-HE-Tag: pest98_0d12dde27339 X-Filterd-Recvd-Size: 4963 Received: from latitanza.investici.org (latitanza.investici.org [82.94.249.234]) by imf33.hostedemail.com (Postfix) with ESMTP for ; Wed, 18 Nov 2020 11:07:52 +0000 (UTC) Received: from mx3.investici.org (unknown [127.0.0.1]) by latitanza.investici.org (Postfix) with ESMTP id 4Cbg5L6SJjz8sh4; Wed, 18 Nov 2020 11:07:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=privacyrequired.com; s=stigmate; t=1605697670; bh=v2/DaV8STEEMs9x+B77A7l6psuLVf/YLdYQGCG8Qjcg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=AFtoFdEnovnNhDGYxAgxnVp5P8xVWxuls0UOmP1I7SEc+DoJ92L60K0M/Bx0M9tRB Hd8Cwbo17r3Kvxq9/9dBSSWBr+UjUrbhLGMKnF6w5rCpRp/PZ9OmDEUgtFSv+Pb3Ir rKEcdaN0GBffgSzaqFV41whkK1yeGOq7EeCAExrY= Received: from [82.94.249.234] (mx3.investici.org [82.94.249.234]) (Authenticated sender: laniel_francis@privacyrequired.com) by localhost (Postfix) with ESMTPSA id 4Cbg5L13rBz8sgF; Wed, 18 Nov 2020 11:07:49 +0000 (UTC) From: laniel_francis@privacyrequired.com To: akpm@linux-foundation.org Cc: linux-hardening@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, dja@axtens.net, keescook@chromium.org Subject: [PATCH v5 2/5] lkdtm: tests for FORTIFY_SOURCE Date: Wed, 18 Nov 2020 12:07:28 +0100 Message-Id: <20201118110731.15833-3-laniel_francis@privacyrequired.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20201118110731.15833-1-laniel_francis@privacyrequired.com> References: <20201118110731.15833-1-laniel_francis@privacyrequired.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Daniel Axtens Add code to test both: - runtime detection of the overrun of a structure. This covers the __builtin_object_size(x, 0) case. This test is called FORTIFY_OBJECT. - runtime detection of the overrun of a char array within a structure. This covers the __builtin_object_size(x, 1) case which can be used for some string functions. This test is called FORTIFY_SUBOBJECT. Suggested-by: Kees Cook Reviewed-by: Kees Cook Signed-off-by: Daniel Axtens --- drivers/misc/lkdtm/bugs.c | 50 ++++++++++++++++++++++++++++++++++++++ drivers/misc/lkdtm/core.c | 2 ++ drivers/misc/lkdtm/lkdtm.h | 2 ++ 3 files changed, 54 insertions(+) diff --git a/drivers/misc/lkdtm/bugs.c b/drivers/misc/lkdtm/bugs.c index a0675d4154d2..110f5a8538e9 100644 --- a/drivers/misc/lkdtm/bugs.c +++ b/drivers/misc/lkdtm/bugs.c @@ -482,3 +482,53 @@ noinline void lkdtm_CORRUPT_PAC(void) pr_err("XFAIL: this test is arm64-only\n"); #endif } + +void lkdtm_FORTIFY_OBJECT(void) +{ + struct target { + char a[10]; + } target[2] =3D {}; + int result; + + /* + * Using volatile prevents the compiler from determining the value of + * 'size' at compile time. Without that, we would get a compile error + * rather than a runtime error. + */ + volatile int size =3D 11; + + pr_info("trying to read past the end of a struct\n"); + + result =3D memcmp(&target[0], &target[1], size); + + /* Print result to prevent the code from being eliminated */ + pr_err("FAIL: fortify did not catch an object overread!\n" + "\"%d\" was the memcmp result.\n", result); +} + +void lkdtm_FORTIFY_SUBOBJECT(void) +{ + struct target { + char a[10]; + char b[10]; + } target; + char *src; + + src =3D kmalloc(20, GFP_KERNEL); + strscpy(src, "over ten bytes", 20); + + pr_info("trying to strcpy past the end of a member of a struct\n"); + + /* + * strncpy(target.a, src, 20); will hit a compile error because the + * compiler knows at build time that target.a < 20 bytes. Use strcpy() + * to force a runtime error. + */ + strcpy(target.a, src); + + /* Use target.a to prevent the code from being eliminated */ + pr_err("FAIL: fortify did not catch an sub-object overrun!\n" + "\"%s\" was copied.\n", target.a); + + kfree(src); +} diff --git a/drivers/misc/lkdtm/core.c b/drivers/misc/lkdtm/core.c index 97803f213d9d..b8c51a633fcc 100644 --- a/drivers/misc/lkdtm/core.c +++ b/drivers/misc/lkdtm/core.c @@ -117,6 +117,8 @@ static const struct crashtype crashtypes[] =3D { CRASHTYPE(UNSET_SMEP), CRASHTYPE(CORRUPT_PAC), CRASHTYPE(UNALIGNED_LOAD_STORE_WRITE), + CRASHTYPE(FORTIFY_OBJECT), + CRASHTYPE(FORTIFY_SUBOBJECT), CRASHTYPE(OVERWRITE_ALLOCATION), CRASHTYPE(WRITE_AFTER_FREE), CRASHTYPE(READ_AFTER_FREE), diff --git a/drivers/misc/lkdtm/lkdtm.h b/drivers/misc/lkdtm/lkdtm.h index 6dec4c9b442f..49e6b945feb7 100644 --- a/drivers/misc/lkdtm/lkdtm.h +++ b/drivers/misc/lkdtm/lkdtm.h @@ -32,6 +32,8 @@ void lkdtm_STACK_GUARD_PAGE_TRAILING(void); void lkdtm_UNSET_SMEP(void); void lkdtm_DOUBLE_FAULT(void); void lkdtm_CORRUPT_PAC(void); +void lkdtm_FORTIFY_OBJECT(void); +void lkdtm_FORTIFY_SUBOBJECT(void); =20 /* lkdtm_heap.c */ void __init lkdtm_heap_init(void); --=20 2.20.1