From patchwork Mon Aug 14 08:41:01 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Aleksa Sarai X-Patchwork-Id: 713669 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 A5DE3C04FE2 for ; Mon, 14 Aug 2023 08:42:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234740AbjHNImY (ORCPT ); Mon, 14 Aug 2023 04:42:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46792 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234757AbjHNIl5 (ORCPT ); Mon, 14 Aug 2023 04:41:57 -0400 Received: from mout-p-101.mailbox.org (mout-p-101.mailbox.org [IPv6:2001:67c:2050:0:465::101]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A0E3A12E; Mon, 14 Aug 2023 01:41:55 -0700 (PDT) Received: from smtp202.mailbox.org (smtp202.mailbox.org [10.196.197.202]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-384) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mout-p-101.mailbox.org (Postfix) with ESMTPS id 4RPSYr29qcz9sn2; Mon, 14 Aug 2023 10:41:52 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cyphar.com; s=MBO0001; t=1692002512; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=W7cNopV9QtwDfWAl6SLw4jWogCD7aoRQLSKJtTeB2Z4=; b=RMj4CUJ8Rvd/ZNQXo32QMV7F9lurzqTpsl02OwCu1jTFQ0n1d0fmf72WxHZ1ua+c7jCd9S D1E9rniYp4s34lLn7rTOmuQpmh3X6pRzrzURyHouUZnlH8th5qc4KVaHELYz6gQeWZpln9 Vgr+Uwo20A0DzCdzDAKx/PsWiZrylfeBS0edlCGMrrdZhKBQMuJCc+nW+saFy+eUxwGf0d /C3mvRd8NQMshleiI648XFnhOm+WbbnHPwtFAXk+GOcWLpgSGxvim4H+QKq7B+9A3O8LTY AMH1dOh1rk34EaAWtAIFNW6K9gvaZ1cf5MF5xsgbBghS5oC5H3C0dlRfJeTWbA== From: Aleksa Sarai Date: Mon, 14 Aug 2023 18:41:01 +1000 Subject: [PATCH v2 5/5] selftests: improve vm.memfd_noexec sysctl tests MIME-Version: 1.0 Message-Id: <20230814-memfd-vm-noexec-uapi-fixes-v2-5-7ff9e3e10ba6@cyphar.com> References: <20230814-memfd-vm-noexec-uapi-fixes-v2-0-7ff9e3e10ba6@cyphar.com> In-Reply-To: <20230814-memfd-vm-noexec-uapi-fixes-v2-0-7ff9e3e10ba6@cyphar.com> To: Andrew Morton , Shuah Khan , Jeff Xu , Kees Cook , Daniel Verkamp Cc: Christian Brauner , Dominique Martinet , stable@vger.kernel.org, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, Aleksa Sarai X-Developer-Signature: v=1; a=openpgp-sha256; l=13000; i=cyphar@cyphar.com; h=from:subject:message-id; bh=0sdx3MhmB3vX/NM+/SK9/yhr9yRSi3Geq1KMMGDcLxI=; b=owGbwMvMwCWmMf3Xpe0vXfIZT6slMaTcfLG2x/3+jGwuzwQtTl/LxLKg180rat3ZkqJalPZ28 m4xPnS+o5SFQYyLQVZMkWWbn2fopvmLryR/WskGM4eVCWQIAxenAEzk2QFGhs4PXJ+fSNazrA34 9lOx7d2F0lMb0t2/9PwKXp7O0yOxYwkjwxtGGx9O5lVLjRPsOj1U3HqnnHOabjbXuDJo82yHIOl 6XgA= X-Developer-Key: i=cyphar@cyphar.com; a=openpgp; fpr=C9C370B246B09F6DBCFC744C34401015D1D2D386 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org This adds proper tests for the nesting functionality of vm.memfd_noexec as well as some minor cleanups to spawn_*_thread(). Signed-off-by: Aleksa Sarai --- tools/testing/selftests/memfd/memfd_test.c | 339 +++++++++++++++++++++-------- 1 file changed, 254 insertions(+), 85 deletions(-) diff --git a/tools/testing/selftests/memfd/memfd_test.c b/tools/testing/selftests/memfd/memfd_test.c index 8b7390ad81d1..3df008677239 100644 --- a/tools/testing/selftests/memfd/memfd_test.c +++ b/tools/testing/selftests/memfd/memfd_test.c @@ -18,6 +18,7 @@ #include #include #include +#include #include "common.h" @@ -43,7 +44,6 @@ */ static size_t mfd_def_size = MFD_DEF_SIZE; static const char *memfd_str = MEMFD_STR; -static pid_t spawn_newpid_thread(unsigned int flags, int (*fn)(void *)); static int newpid_thread_fn2(void *arg); static void join_newpid_thread(pid_t pid); @@ -96,12 +96,12 @@ static void sysctl_assert_write(const char *val) int fd = open("/proc/sys/vm/memfd_noexec", O_WRONLY | O_CLOEXEC); if (fd < 0) { - printf("open sysctl failed\n"); + printf("open sysctl failed: %m\n"); abort(); } if (write(fd, val, strlen(val)) < 0) { - printf("write sysctl failed\n"); + printf("write sysctl %s failed: %m\n", val); abort(); } } @@ -111,7 +111,7 @@ static void sysctl_fail_write(const char *val) int fd = open("/proc/sys/vm/memfd_noexec", O_WRONLY | O_CLOEXEC); if (fd < 0) { - printf("open sysctl failed\n"); + printf("open sysctl failed: %m\n"); abort(); } @@ -122,6 +122,33 @@ static void sysctl_fail_write(const char *val) } } +static void sysctl_assert_equal(const char *val) +{ + char *p, buf[128] = {}; + int fd = open("/proc/sys/vm/memfd_noexec", O_RDONLY | O_CLOEXEC); + + if (fd < 0) { + printf("open sysctl failed: %m\n"); + abort(); + } + + if (read(fd, buf, sizeof(buf)) < 0) { + printf("read sysctl failed: %m\n"); + abort(); + } + + /* Strip trailing whitespace. */ + p = buf; + while (!isspace(*p)) + p++; + *p = '\0'; + + if (strcmp(buf, val) != 0) { + printf("unexpected sysctl value: expected %s, got %s\n", val, buf); + abort(); + } +} + static int mfd_assert_reopen_fd(int fd_in) { int fd; @@ -736,7 +763,7 @@ static int idle_thread_fn(void *arg) return 0; } -static pid_t spawn_idle_thread(unsigned int flags) +static pid_t spawn_thread(unsigned int flags, int (*fn)(void *), void *arg) { uint8_t *stack; pid_t pid; @@ -747,10 +774,7 @@ static pid_t spawn_idle_thread(unsigned int flags) abort(); } - pid = clone(idle_thread_fn, - stack + STACK_SIZE, - SIGCHLD | flags, - NULL); + pid = clone(fn, stack + STACK_SIZE, SIGCHLD | flags, arg); if (pid < 0) { printf("clone() failed: %m\n"); abort(); @@ -759,6 +783,33 @@ static pid_t spawn_idle_thread(unsigned int flags) return pid; } +static void join_thread(pid_t pid) +{ + int wstatus; + + if (waitpid(pid, &wstatus, 0) < 0) { + printf("newpid thread: waitpid() failed: %m\n"); + abort(); + } + + if (WIFEXITED(wstatus) && WEXITSTATUS(wstatus) != 0) { + printf("newpid thread: exited with non-zero error code %d\n", + WEXITSTATUS(wstatus)); + abort(); + } + + if (WIFSIGNALED(wstatus)) { + printf("newpid thread: killed by signal %d\n", + WTERMSIG(wstatus)); + abort(); + } +} + +static pid_t spawn_idle_thread(unsigned int flags) +{ + return spawn_thread(flags, idle_thread_fn, NULL); +} + static void join_idle_thread(pid_t pid) { kill(pid, SIGTERM); @@ -1111,42 +1162,69 @@ static void test_noexec_seal(void) close(fd); } -static void test_sysctl_child(void) +static void test_sysctl_sysctl0(void) { int fd; - int pid; - printf("%s sysctl 0\n", memfd_str); - sysctl_assert_write("0"); - fd = mfd_assert_new("kern_memfd_sysctl_0", + sysctl_assert_equal("0"); + + fd = mfd_assert_new("kern_memfd_sysctl_0_dfl", mfd_def_size, MFD_CLOEXEC | MFD_ALLOW_SEALING); - mfd_assert_mode(fd, 0777); mfd_assert_has_seals(fd, 0); mfd_assert_chmod(fd, 0644); close(fd); +} - printf("%s sysctl 1\n", memfd_str); - sysctl_assert_write("1"); - fd = mfd_assert_new("kern_memfd_sysctl_1", +static void test_sysctl_set_sysctl0(void) +{ + sysctl_assert_write("0"); + test_sysctl_sysctl0(); +} + +static void test_sysctl_sysctl1(void) +{ + int fd; + + sysctl_assert_equal("1"); + + fd = mfd_assert_new("kern_memfd_sysctl_1_dfl", mfd_def_size, MFD_CLOEXEC | MFD_ALLOW_SEALING); + mfd_assert_mode(fd, 0666); + mfd_assert_has_seals(fd, F_SEAL_EXEC); + mfd_fail_chmod(fd, 0777); + close(fd); - printf("%s child ns\n", memfd_str); - pid = spawn_newpid_thread(CLONE_NEWPID, newpid_thread_fn2); - join_newpid_thread(pid); + fd = mfd_assert_new("kern_memfd_sysctl_1_exec", + mfd_def_size, + MFD_CLOEXEC | MFD_EXEC | MFD_ALLOW_SEALING); + mfd_assert_mode(fd, 0777); + mfd_assert_has_seals(fd, 0); + mfd_assert_chmod(fd, 0644); + close(fd); + fd = mfd_assert_new("kern_memfd_sysctl_1_noexec", + mfd_def_size, + MFD_CLOEXEC | MFD_NOEXEC_SEAL | MFD_ALLOW_SEALING); mfd_assert_mode(fd, 0666); mfd_assert_has_seals(fd, F_SEAL_EXEC); mfd_fail_chmod(fd, 0777); - sysctl_fail_write("0"); close(fd); +} - printf("%s sysctl 2\n", memfd_str); - sysctl_assert_write("2"); - mfd_fail_new("kern_memfd_sysctl_2_exec", - MFD_EXEC | MFD_CLOEXEC | MFD_ALLOW_SEALING); +static void test_sysctl_set_sysctl1(void) +{ + sysctl_assert_write("1"); + test_sysctl_sysctl1(); +} + +static void test_sysctl_sysctl2(void) +{ + int fd; + + sysctl_assert_equal("2"); fd = mfd_assert_new("kern_memfd_sysctl_2_dfl", mfd_def_size, @@ -1156,98 +1234,188 @@ static void test_sysctl_child(void) mfd_fail_chmod(fd, 0777); close(fd); - fd = mfd_assert_new("kern_memfd_sysctl_2_noexec_seal", + mfd_fail_new("kern_memfd_sysctl_2_exec", + MFD_CLOEXEC | MFD_EXEC | MFD_ALLOW_SEALING); + + fd = mfd_assert_new("kern_memfd_sysctl_2_noexec", mfd_def_size, - MFD_NOEXEC_SEAL | MFD_CLOEXEC | MFD_ALLOW_SEALING); + MFD_CLOEXEC | MFD_NOEXEC_SEAL | MFD_ALLOW_SEALING); mfd_assert_mode(fd, 0666); mfd_assert_has_seals(fd, F_SEAL_EXEC); mfd_fail_chmod(fd, 0777); close(fd); - - sysctl_fail_write("0"); - sysctl_fail_write("1"); } -static int newpid_thread_fn(void *arg) +static void test_sysctl_set_sysctl2(void) { - test_sysctl_child(); - return 0; + sysctl_assert_write("2"); + test_sysctl_sysctl2(); } -static void test_sysctl_child2(void) +static int sysctl_simple_child(void *arg) { int fd; + int pid; - sysctl_fail_write("0"); - fd = mfd_assert_new("kern_memfd_sysctl_1", - mfd_def_size, - MFD_CLOEXEC | MFD_ALLOW_SEALING); + printf("%s sysctl 0\n", memfd_str); + test_sysctl_set_sysctl0(); - mfd_assert_mode(fd, 0666); - mfd_assert_has_seals(fd, F_SEAL_EXEC); - mfd_fail_chmod(fd, 0777); - close(fd); + printf("%s sysctl 1\n", memfd_str); + test_sysctl_set_sysctl1(); + + printf("%s sysctl 0\n", memfd_str); + test_sysctl_set_sysctl0(); + + printf("%s sysctl 2\n", memfd_str); + test_sysctl_set_sysctl2(); + + printf("%s sysctl 1\n", memfd_str); + test_sysctl_set_sysctl1(); + + printf("%s sysctl 0\n", memfd_str); + test_sysctl_set_sysctl0(); + + return 0; +} + +/* + * Test sysctl + * A very basic test to make sure the core sysctl semantics work. + */ +static void test_sysctl_simple(void) +{ + int pid = spawn_thread(CLONE_NEWPID, sysctl_simple_child, NULL); + + join_thread(pid); } -static int newpid_thread_fn2(void *arg) +static int sysctl_nested(void *arg) { - test_sysctl_child2(); + void (*fn)(void) = arg; + + fn(); return 0; } -static pid_t spawn_newpid_thread(unsigned int flags, int (*fn)(void *)) + +static int sysctl_nested_wait(void *arg) { - uint8_t *stack; - pid_t pid; + /* Wait for a SIGCONT. */ + kill(getpid(), SIGSTOP); + return sysctl_nested(arg); +} - stack = malloc(STACK_SIZE); - if (!stack) { - printf("malloc(STACK_SIZE) failed: %m\n"); - abort(); - } +static void test_sysctl_sysctl1_failset(void) +{ + sysctl_fail_write("0"); + test_sysctl_sysctl1(); +} - pid = clone(fn, - stack + STACK_SIZE, - SIGCHLD | flags, - NULL); - if (pid < 0) { - printf("clone() failed: %m\n"); - abort(); - } +static void test_sysctl_sysctl2_failset(void) +{ + sysctl_fail_write("1"); + test_sysctl_sysctl2(); - return pid; + sysctl_fail_write("0"); + test_sysctl_sysctl2(); } -static void join_newpid_thread(pid_t pid) +static int sysctl_nested_child(void *arg) { - int wstatus; + int fd; + int pid; - if (waitpid(pid, &wstatus, 0) < 0) { - printf("newpid thread: waitpid() failed: %m\n"); - abort(); - } + printf("%s nested sysctl 0\n", memfd_str); + sysctl_assert_write("0"); + /* A further nested pidns works the same. */ + pid = spawn_thread(CLONE_NEWPID, sysctl_simple_child, NULL); + join_thread(pid); - if (WIFEXITED(wstatus) && WEXITSTATUS(wstatus) != 0) { - printf("newpid thread: exited with non-zero error code %d\n", - WEXITSTATUS(wstatus)); - abort(); - } + printf("%s nested sysctl 1\n", memfd_str); + sysctl_assert_write("1"); + /* Child inherits our setting. */ + pid = spawn_thread(CLONE_NEWPID, sysctl_nested, test_sysctl_sysctl1); + join_thread(pid); + /* Child cannot raise the setting. */ + pid = spawn_thread(CLONE_NEWPID, sysctl_nested, + test_sysctl_sysctl1_failset); + join_thread(pid); + /* Child can lower the setting. */ + pid = spawn_thread(CLONE_NEWPID, sysctl_nested, + test_sysctl_set_sysctl2); + join_thread(pid); + /* Child lowering the setting has no effect on our setting. */ + test_sysctl_sysctl1(); + + printf("%s nested sysctl 2\n", memfd_str); + sysctl_assert_write("2"); + /* Child inherits our setting. */ + pid = spawn_thread(CLONE_NEWPID, sysctl_nested, test_sysctl_sysctl2); + join_thread(pid); + /* Child cannot raise the setting. */ + pid = spawn_thread(CLONE_NEWPID, sysctl_nested, + test_sysctl_sysctl2_failset); + join_thread(pid); + + /* Verify that the rules are actually inherited after fork. */ + printf("%s nested sysctl 0 -> 1 after fork\n", memfd_str); + sysctl_assert_write("0"); - if (WIFSIGNALED(wstatus)) { - printf("newpid thread: killed by signal %d\n", - WTERMSIG(wstatus)); - abort(); - } + pid = spawn_thread(CLONE_NEWPID, sysctl_nested_wait, + test_sysctl_sysctl1_failset); + sysctl_assert_write("1"); + kill(pid, SIGCONT); + join_thread(pid); + + printf("%s nested sysctl 0 -> 2 after fork\n", memfd_str); + sysctl_assert_write("0"); + + pid = spawn_thread(CLONE_NEWPID, sysctl_nested_wait, + test_sysctl_sysctl2_failset); + sysctl_assert_write("2"); + kill(pid, SIGCONT); + join_thread(pid); + + /* + * Verify that the current effective setting is saved on fork, meaning + * that the parent lowering the sysctl doesn't affect already-forked + * children. + */ + printf("%s nested sysctl 2 -> 1 after fork\n", memfd_str); + sysctl_assert_write("2"); + pid = spawn_thread(CLONE_NEWPID, sysctl_nested_wait, + test_sysctl_sysctl2); + sysctl_assert_write("1"); + kill(pid, SIGCONT); + join_thread(pid); + + printf("%s nested sysctl 2 -> 0 after fork\n", memfd_str); + sysctl_assert_write("2"); + pid = spawn_thread(CLONE_NEWPID, sysctl_nested_wait, + test_sysctl_sysctl2); + sysctl_assert_write("0"); + kill(pid, SIGCONT); + join_thread(pid); + + printf("%s nested sysctl 1 -> 0 after fork\n", memfd_str); + sysctl_assert_write("1"); + pid = spawn_thread(CLONE_NEWPID, sysctl_nested_wait, + test_sysctl_sysctl1); + sysctl_assert_write("0"); + kill(pid, SIGCONT); + join_thread(pid); + + return 0; } /* - * Test sysctl - * A very basic sealing test to see whether setting/retrieving seals works. + * Test sysctl with nested pid namespaces + * Make sure that the sysctl nesting semantics work correctly. */ -static void test_sysctl(void) +static void test_sysctl_nested(void) { - int pid = spawn_newpid_thread(CLONE_NEWPID, newpid_thread_fn); + int pid = spawn_thread(CLONE_NEWPID, sysctl_nested_child, NULL); - join_newpid_thread(pid); + join_thread(pid); } /* @@ -1433,6 +1601,9 @@ int main(int argc, char **argv) test_seal_grow(); test_seal_resize(); + test_sysctl_simple(); + test_sysctl_nested(); + test_share_dup("SHARE-DUP", ""); test_share_mmap("SHARE-MMAP", ""); test_share_open("SHARE-OPEN", ""); @@ -1447,8 +1618,6 @@ int main(int argc, char **argv) test_share_fork("SHARE-FORK", SHARED_FT_STR); join_idle_thread(pid); - test_sysctl(); - printf("memfd: DONE\n"); return 0;