From patchwork Fri Apr 1 22:08:33 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Verkamp X-Patchwork-Id: 12798821 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id F1C99C433FE for ; Fri, 1 Apr 2022 22:08:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1353231AbiDAWKq (ORCPT ); Fri, 1 Apr 2022 18:10:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48056 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1353233AbiDAWKo (ORCPT ); Fri, 1 Apr 2022 18:10:44 -0400 Received: from mail-pf1-x42b.google.com (mail-pf1-x42b.google.com [IPv6:2607:f8b0:4864:20::42b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BC9AE3B54F for ; Fri, 1 Apr 2022 15:08:54 -0700 (PDT) Received: by mail-pf1-x42b.google.com with SMTP id h19so3846348pfv.1 for ; Fri, 01 Apr 2022 15:08:54 -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=W2dIS9P9cYggnNka+4k4Gn63M8GjebQJazBSK4gQ59E=; b=Cr8pY9ZyZkOJCluc/iz4NzKGM5yjTCERCc07lJqJ64lxXC8WM7aZ3lRaioUTSrh1uP fnNA8gzv7T3fB/mIuXCSe/fDWMjiR+M9lYmcB1a56kj/OmmUyAJKjnV/XNb8nJ4v2hbZ upohpJPABZs86wqi/TJXNyrjsZ+clUnpfPNhU= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=W2dIS9P9cYggnNka+4k4Gn63M8GjebQJazBSK4gQ59E=; b=hY+Ls7MC68QUOkKHFuoq6jTGbw35BZUjvEZ3SiOz5g3WFRPyai6Ld5PCX7Y0088rqQ iLWZg/Oigh3pPlkGgC5iaw4+XZD+Fv5862GwdAKmb70DsrL0wl+tDCFxbDG56UFBdilF xFT22syKb6oGVyy3gRaztZMEWktsqNc+C1I6Co7EmXimD/TpY0hA/DAld/71ZBJ5HNVd a9wbzb7EBjiVUEMnMLo74amYYzcKThuyM6BYWWKBsYZCG4tjvnwtN69Jg+bTEp117n+/ jDIGnsus+rcSWbMODtAGT5xSP9npqc1NsLX0Q2zc1NuoqFNwl57EocT6R3sNKdfkj7Mq Cuag== X-Gm-Message-State: AOAM530OYllfJOuxuKk4FJ2uD5hY+1GttFJUzJUulj6iMweerA5ZiVhz BcJgli+hrdXx+KDjQ2d6O6R8bA== X-Google-Smtp-Source: ABdhPJzxAVHoX6VACxIQgKkefSjLO46zf4cJLaQQXIcLa57xWR5jeIRu2USsxHabbOHOptJtDZDWeg== X-Received: by 2002:a05:6a00:1488:b0:4fa:ac61:8b11 with SMTP id v8-20020a056a00148800b004faac618b11mr13204273pfu.58.1648850934155; Fri, 01 Apr 2022 15:08:54 -0700 (PDT) Received: from localhost ([2620:15c:202:201:72c9:527e:d936:c24b]) by smtp.gmail.com with UTF8SMTPSA id oc10-20020a17090b1c0a00b001c7510ed0c8sm14841905pjb.49.2022.04.01.15.08.52 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 01 Apr 2022 15:08:53 -0700 (PDT) From: Daniel Verkamp To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, Andrew Morton , Hugh Dickins , Mattias Nissler , Dmitry Torokhov , Kees Cook , Daniel Verkamp Subject: [PATCH 3/4] selftests/memfd: add tests for F_SEAL_EXEC Date: Fri, 1 Apr 2022 15:08:33 -0700 Message-Id: <20220401220834.307660-4-dverkamp@chromium.org> X-Mailer: git-send-email 2.35.1.1094.g7c7d902a7c-goog In-Reply-To: <20220401220834.307660-1-dverkamp@chromium.org> References: <20220401220834.307660-1-dverkamp@chromium.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Basic tests to ensure that user/group/other execute bits cannot be changed after applying F_SEAL_EXEC to a memfd. Signed-off-by: Daniel Verkamp --- tools/testing/selftests/memfd/memfd_test.c | 80 ++++++++++++++++++++++ 1 file changed, 80 insertions(+) diff --git a/tools/testing/selftests/memfd/memfd_test.c b/tools/testing/selftests/memfd/memfd_test.c index 94df2692e6e4..fdb0e46e9df9 100644 --- a/tools/testing/selftests/memfd/memfd_test.c +++ b/tools/testing/selftests/memfd/memfd_test.c @@ -28,6 +28,10 @@ #define MFD_DEF_SIZE 8192 #define STACK_SIZE 65536 +#ifndef F_SEAL_EXEC +#define F_SEAL_EXEC 0x0020 +#endif + /* * Default is not to test hugetlbfs */ @@ -594,6 +598,48 @@ static void mfd_fail_grow_write(int fd) } } +static void mfd_assert_mode(int fd, int mode) +{ + struct stat st; + + if (fstat(fd, &st) < 0) { + printf("fstat(%d) failed: %m\n", fd); + abort(); + } else if ((st.st_mode & 07777) != mode) { + printf("wrong file mode 0%04o, but expected 0%04o\n", + (int)st.st_mode & 07777, mode); + abort(); + } +} + +static void mfd_assert_chmod(int fd, int mode) +{ + if (fchmod(fd, mode) < 0) { + printf("fchmod(0%04o) failed: %m\n", mode); + abort(); + } + + mfd_assert_mode(fd, mode); +} + +static void mfd_fail_chmod(int fd, int mode) +{ + struct stat st; + + if (fstat(fd, &st) < 0) { + printf("fstat(%d) failed: %m\n", fd); + abort(); + } + + if (fchmod(fd, mode) == 0) { + printf("fchmod(0%04o) didn't fail as expected\n"); + abort(); + } + + /* verify that file mode bits did not change */ + mfd_assert_mode(fd, st.st_mode & 07777); +} + static int idle_thread_fn(void *arg) { sigset_t set; @@ -880,6 +926,39 @@ static void test_seal_resize(void) close(fd); } +/* + * Test SEAL_EXEC + * Test that chmod() cannot change x bits after sealing + */ +static void test_seal_exec(void) +{ + int fd; + + printf("%s SEAL-EXEC\n", memfd_str); + + fd = mfd_assert_new("kern_memfd_seal_exec", + mfd_def_size, + MFD_CLOEXEC | MFD_ALLOW_SEALING); + + mfd_assert_mode(fd, 0777); + + mfd_assert_chmod(fd, 0644); + + mfd_assert_has_seals(fd, 0); + mfd_assert_add_seals(fd, F_SEAL_EXEC); + mfd_assert_has_seals(fd, F_SEAL_EXEC); + + mfd_assert_chmod(fd, 0600); + mfd_fail_chmod(fd, 0777); + mfd_fail_chmod(fd, 0670); + mfd_fail_chmod(fd, 0605); + mfd_fail_chmod(fd, 0700); + mfd_fail_chmod(fd, 0100); + mfd_assert_chmod(fd, 0666); + + close(fd); +} + /* * Test sharing via dup() * Test that seals are shared between dupped FDs and they're all equal. @@ -1059,6 +1138,7 @@ int main(int argc, char **argv) test_seal_shrink(); test_seal_grow(); test_seal_resize(); + test_seal_exec(); test_share_dup("SHARE-DUP", ""); test_share_mmap("SHARE-MMAP", "");