From patchwork Fri Aug 5 22:21:24 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Xu X-Patchwork-Id: 595680 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 D7AF1C3F6B0 for ; Fri, 5 Aug 2022 22:22:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241821AbiHEWWB (ORCPT ); Fri, 5 Aug 2022 18:22:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36368 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241790AbiHEWVy (ORCPT ); Fri, 5 Aug 2022 18:21:54 -0400 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8722E1B786 for ; Fri, 5 Aug 2022 15:21:53 -0700 (PDT) Received: by mail-yb1-xb49.google.com with SMTP id c9-20020a5b0989000000b0067b7758254cso3093171ybq.14 for ; Fri, 05 Aug 2022 15:21:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=8AvsEq4SstPGeW7QF9LLj/CM82M+f11wZB7WzW/AmUg=; b=mMb+PeyF4VQkekJjv1Q+X2LF/3kKZ0J2TCbHkTTU/n5K6SxiBoS32IjQbd7vR1JBuY KK5mNxKRvJhbNpXkBgLNsjozyQGZZykaqk9VJaar90tvBTvpEwaJWc/oPcu8lkQsledi CfI3NYgAM5qa/N6/BrSW4XoQzQJwhjQqwzUAlLdH+uaizI1Yde5jEVhQMh4/W4ts0DRC nTZKmQYKwiV5MoJ69N1hpt8b+LYHYMNfd2Tl2jK9YjWAMNbaO4NhjiFuji/3ZwNy8TCO iFrzR+jYcS+CMSO5r4DA1Bvpyvedk6yb/v6haitjoDbX9YF4zss9+D/gTqEGtTKwy5vd 1RBw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=8AvsEq4SstPGeW7QF9LLj/CM82M+f11wZB7WzW/AmUg=; b=kILoaI1Z7zLNFsCSg9yiNZonnymwB9VHyVZQXVUcp5daZKBcr3xy6hWNZW6FqUj6sh gWYeKSnoh7Wy6tny8btkMGEQdZIUoCCd/9AvoatB/k9zK9HTbdFehOmfuPI7aF4uyVe+ Jw8SpJyTjM/8y69rHu5fre7CWwiKgQzcmECjo58TS9wwfU6Lvv15yC+5VVX/Eay1xkc1 PPx3r/JijJYIzRzd+489X7yUCV/qRBIMER0TyXBN85WSo9gc5vnAZzrKCzifeR1BdljA M0K+HmJn/K43EeQGGVM8y6Q6jyftJzqsTBSQuqb2K4SMsZud+SOCsYD0VGdrDpsXICVC a0rQ== X-Gm-Message-State: ACgBeo3+bBJIWmzszOs/Sh9/N5kPQ+LyFTaEq3al8nFwglOtb9YabFIN fbhvfy7NGxTWlDkbrRfI0CGzbbwbk/U= X-Google-Smtp-Source: AA6agR7MhJWGNuJekXT5wplu+5rroD6wgWIQKDgy1c8mBYuUwU+BizAsUUXtqWQTJ2dbcZa+Q1JevcSWC98= X-Received: from jeffxud.c.googlers.com ([fda3:e722:ac3:cc00:20:ed76:c0a8:e37]) (user=jeffxu job=sendgmr) by 2002:a81:7b85:0:b0:321:119:5a0d with SMTP id w127-20020a817b85000000b0032101195a0dmr8242026ywc.55.1659738112795; Fri, 05 Aug 2022 15:21:52 -0700 (PDT) Date: Fri, 5 Aug 2022 22:21:24 +0000 In-Reply-To: <20220805222126.142525-1-jeffxu@google.com> Message-Id: <20220805222126.142525-4-jeffxu@google.com> Mime-Version: 1.0 References: <20220805222126.142525-1-jeffxu@google.com> X-Mailer: git-send-email 2.37.1.559.g78731f0fdb-goog Subject: [PATCH v2 3/5] selftests/memfd: add tests for F_SEAL_EXEC From: To: skhan@linuxfoundation.org Cc: akpm@linux-foundation.org, dmitry.torokhov@gmail.com, dverkamp@chromium.org, hughd@google.com, jeffxu@google.com, jorgelo@chromium.org, keescook@chromium.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, mnissler@chromium.org, jannh@google.com, Jeff Xu Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org From: Daniel Verkamp Basic tests to ensure that user/group/other execute bits cannot be changed after applying F_SEAL_EXEC to a memfd. Co-developed-by: Jeff Xu Signed-off-by: Jeff Xu Signed-off-by: Daniel Verkamp --- tools/testing/selftests/memfd/memfd_test.c | 129 ++++++++++++++++++++- 1 file changed, 128 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/memfd/memfd_test.c b/tools/testing/selftests/memfd/memfd_test.c index 94df2692e6e4..1d7e7b36bbdd 100644 --- a/tools/testing/selftests/memfd/memfd_test.c +++ b/tools/testing/selftests/memfd/memfd_test.c @@ -28,12 +28,44 @@ #define MFD_DEF_SIZE 8192 #define STACK_SIZE 65536 +#ifndef F_SEAL_EXEC +#define F_SEAL_EXEC 0x0020 +#endif + +#ifndef MAX_PATH +#define MAX_PATH 256 +#endif + /* * Default is not to test hugetlbfs */ static size_t mfd_def_size = MFD_DEF_SIZE; static const char *memfd_str = MEMFD_STR; +static ssize_t fd2name(int fd, char *buf, size_t bufsize) +{ + char buf1[MAX_PATH]; + int size; + ssize_t nbytes; + + size = snprintf(buf1, MAX_PATH, "/proc/self/fd/%d", fd); + if (size < 0) { + printf("snprintf(%d) failed on %m\n", fd); + abort(); + } + + /* + * reserver one byte for string termination. + */ + nbytes = readlink(buf1, buf, bufsize-1); + if (nbytes == -1) { + printf("readlink(%s) failed %m\n", buf1); + abort(); + } + buf[nbytes] = '\0'; + return nbytes; +} + static int mfd_assert_new(const char *name, loff_t sz, unsigned int flags) { int r, fd; @@ -98,11 +130,14 @@ static unsigned int mfd_assert_get_seals(int fd) static void mfd_assert_has_seals(int fd, unsigned int seals) { + char buf[MAX_PATH]; + int nbytes; unsigned int s; + fd2name(fd, buf, MAX_PATH); s = mfd_assert_get_seals(fd); if (s != seals) { - printf("%u != %u = GET_SEALS(%d)\n", seals, s, fd); + printf("%u != %u = GET_SEALS(%s)\n", seals, s, buf); abort(); } } @@ -594,6 +629,64 @@ static void mfd_fail_grow_write(int fd) } } +static void mfd_assert_mode(int fd, int mode) +{ + struct stat st; + char buf[MAX_PATH]; + int nbytes; + + fd2name(fd, buf, MAX_PATH); + + if (fstat(fd, &st) < 0) { + printf("fstat(%s) failed: %m\n", buf); + abort(); + } + + if ((st.st_mode & 07777) != mode) { + printf("fstat(%s) wrong file mode 0%04o, but expected 0%04o\n", + buf, (int)st.st_mode & 07777, mode); + abort(); + } +} + +static void mfd_assert_chmod(int fd, int mode) +{ + char buf[MAX_PATH]; + int nbytes; + + fd2name(fd, buf, MAX_PATH); + + if (fchmod(fd, mode) < 0) { + printf("fchmod(%s, 0%04o) failed: %m\n", buf, mode); + abort(); + } + + mfd_assert_mode(fd, mode); +} + +static void mfd_fail_chmod(int fd, int mode) +{ + struct stat st; + char buf[MAX_PATH]; + int nbytes; + + fd2name(fd, buf, MAX_PATH); + + if (fstat(fd, &st) < 0) { + printf("fstat(%s) failed: %m\n", buf); + abort(); + } + + if (fchmod(fd, mode) == 0) { + printf("fchmod(%s, 0%04o) didn't fail as expected\n", + buf, mode); + 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 +973,39 @@ 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 +1185,7 @@ 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", "");