@@ -37,6 +37,7 @@ TARGETS += powerpc
TARGETS += proc
TARGETS += pstore
TARGETS += ptrace
+TARGETS += openat2
TARGETS += rseq
TARGETS += rtc
TARGETS += seccomp
@@ -925,7 +925,7 @@ static void test_share_mmap(char *banner, char *b_suffix)
*/
static void test_share_open(char *banner, char *b_suffix)
{
- int fd, fd2;
+ int procfd, fd, fd2;
printf("%s %s %s\n", memfd_str, banner, b_suffix);
@@ -950,13 +950,16 @@ static void test_share_open(char *banner, char *b_suffix)
mfd_assert_has_seals(fd, F_SEAL_WRITE | F_SEAL_SHRINK);
mfd_assert_has_seals(fd2, F_SEAL_WRITE | F_SEAL_SHRINK);
+ /* We cannot do a MAY_WRITE re-open of an O_RDONLY fd. */
+ procfd = mfd_assert_open(fd2, O_PATH, 0);
close(fd2);
- fd2 = mfd_assert_open(fd, O_RDWR, 0);
+ fd2 = mfd_assert_open(procfd, O_WRONLY, 0);
mfd_assert_add_seals(fd2, F_SEAL_SEAL);
mfd_assert_has_seals(fd, F_SEAL_WRITE | F_SEAL_SHRINK | F_SEAL_SEAL);
mfd_assert_has_seals(fd2, F_SEAL_WRITE | F_SEAL_SHRINK | F_SEAL_SEAL);
+ close(procfd);
close(fd2);
close(fd);
}
new file mode 100644
@@ -0,0 +1 @@
+/*_test
new file mode 100644
@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+CFLAGS += -Wall -O2 -g -fsanitize=address -fsanitize=undefined
+TEST_GEN_PROGS := linkmode_test openat2_test resolve_test rename_attack_test
+
+include ../lib.mk
+
+$(TEST_GEN_PROGS): helpers.c
new file mode 100644
@@ -0,0 +1,98 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Author: Aleksa Sarai <cyphar@cyphar.com>
+ * Copyright (C) 2018-2019 SUSE LLC.
+ */
+
+#define _GNU_SOURCE
+#include <errno.h>
+#include <fcntl.h>
+#include <stdbool.h>
+#include <string.h>
+#include <syscall.h>
+#include <limits.h>
+
+#include "helpers.h"
+
+int raw_openat2(int dfd, const char *path, const void *how, size_t size)
+{
+ int ret = syscall(__NR_openat2, dfd, path, how, size);
+ return ret >= 0 ? ret : -errno;
+}
+
+int sys_openat2(int dfd, const char *path, const struct open_how *how)
+{
+ return raw_openat2(dfd, path, how, sizeof(*how));
+}
+
+int sys_openat(int dfd, const char *path, const struct open_how *how)
+{
+ int ret = openat(dfd, path, how->flags, how->mode);
+ return ret >= 0 ? ret : -errno;
+}
+
+int sys_renameat2(int olddirfd, const char *oldpath,
+ int newdirfd, const char *newpath, unsigned int flags)
+{
+ int ret = syscall(__NR_renameat2, olddirfd, oldpath,
+ newdirfd, newpath, flags);
+ return ret >= 0 ? ret : -errno;
+}
+
+int touchat(int dfd, const char *path)
+{
+ int fd = openat(dfd, path, O_CREAT);
+ if (fd >= 0)
+ close(fd);
+ return fd;
+}
+
+char *fdreadlink(int fd)
+{
+ char *target, *tmp;
+
+ E_asprintf(&tmp, "/proc/self/fd/%d", fd);
+
+ target = malloc(PATH_MAX);
+ if (!target)
+ ksft_exit_fail_msg("fdreadlink: malloc failed\n");
+ memset(target, 0, PATH_MAX);
+
+ E_readlink(tmp, target, PATH_MAX);
+ free(tmp);
+ return target;
+}
+
+bool fdequal(int fd, int dfd, const char *path)
+{
+ char *fdpath, *dfdpath, *other;
+ bool cmp;
+
+ fdpath = fdreadlink(fd);
+ dfdpath = fdreadlink(dfd);
+
+ if (!path)
+ E_asprintf(&other, "%s", dfdpath);
+ else if (*path == '/')
+ E_asprintf(&other, "%s", path);
+ else
+ E_asprintf(&other, "%s/%s", dfdpath, path);
+
+ cmp = !strcmp(fdpath, other);
+
+ free(fdpath);
+ free(dfdpath);
+ free(other);
+ return cmp;
+}
+
+void test_openat2_supported(void)
+{
+ struct open_how how = {};
+ int fd = sys_openat2(AT_FDCWD, ".", &how);
+ if (fd == -ENOSYS)
+ ksft_exit_skip("openat2(2) unsupported on this kernel\n");
+ if (fd < 0)
+ ksft_exit_fail_msg("openat2(2) supported check failed: %s\n", strerror(-fd));
+ close(fd);
+}
new file mode 100644
@@ -0,0 +1,114 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Author: Aleksa Sarai <cyphar@cyphar.com>
+ * Copyright (C) 2018-2019 SUSE LLC.
+ */
+
+#ifndef __RESOLVEAT_H__
+#define __RESOLVEAT_H__
+
+#define _GNU_SOURCE
+#include <stdint.h>
+#include <errno.h>
+#include "../kselftest.h"
+
+#define ARRAY_LEN(X) (sizeof (X) / sizeof (*(X)))
+#define BUILD_BUG_ON(e) ((void)(sizeof(struct { int:(-!!(e)); })))
+
+#ifndef SYS_openat2
+#ifndef __NR_openat2
+#define __NR_openat2 437
+#endif /* __NR_openat2 */
+#define SYS_openat2 __NR_openat2
+#endif /* SYS_openat2 */
+
+/*
+ * Arguments for how openat2(2) should open the target path. If @extra is zero,
+ * then openat2 is identical to openat(2). Only one of @mode or @upgrade_mask
+ * may be set at any given time.
+ *
+ * @flags: O_* flags (unknown flags ignored).
+ * @mode: O_CREAT file mode (ignored otherwise).
+ * @upgrade_mask: restrict how the O_PATH may be re-opened (ignored otherwise).
+ * @resolve: RESOLVE_* flags (-EINVAL on unknown flags).
+ */
+struct open_how {
+ uint32_t flags;
+ union {
+ uint16_t mode;
+ uint16_t upgrade_mask;
+ };
+ uint16_t resolve;
+};
+
+#define OPEN_HOW_SIZE_VER0 8 /* sizeof first published struct */
+
+#ifndef RESOLVE_IN_ROOT
+/* how->resolve flags for openat2(2). */
+#define RESOLVE_NO_XDEV 0x01 /* Block mount-point crossings
+ (includes bind-mounts). */
+#define RESOLVE_NO_MAGICLINKS 0x02 /* Block traversal through procfs-style
+ "magic-links". */
+#define RESOLVE_NO_SYMLINKS 0x04 /* Block traversal through all symlinks
+ (implies OEXT_NO_MAGICLINKS) */
+#define RESOLVE_BENEATH 0x08 /* Block "lexical" trickery like
+ "..", symlinks, and absolute
+ paths which escape the dirfd. */
+#define RESOLVE_IN_ROOT 0x10 /* Make all jumps to "/" and ".."
+ be scoped inside the dirfd
+ (similar to chroot(2)). */
+#endif /* RESOLVE_IN_ROOT */
+
+#ifndef UPGRADE_NOREAD
+/* how->upgrade flags for openat2(2). */
+/* First bit is reserved for a future UPGRADE_NOEXEC flag. */
+#define UPGRADE_NOREAD 0x02 /* Block re-opening with MAY_READ. */
+#define UPGRADE_NOWRITE 0x04 /* Block re-opening with MAY_WRITE. */
+#endif /* UPGRADE_NOREAD */
+
+#ifndef O_EMPTYPATH
+#define O_EMPTYPATH 040000000
+#endif /* O_EMPTYPATH */
+
+#define E_func(func, ...) \
+ do { \
+ if (func(__VA_ARGS__) < 0) \
+ ksft_exit_fail_msg("%s:%d %s failed\n", \
+ __FILE__, __LINE__, #func);\
+ } while (0)
+
+#define E_asprintf(...) E_func(asprintf, __VA_ARGS__)
+#define E_chmod(...) E_func(chmod, __VA_ARGS__)
+#define E_dup2(...) E_func(dup2, __VA_ARGS__)
+#define E_fchdir(...) E_func(fchdir, __VA_ARGS__)
+#define E_fstatat(...) E_func(fstatat, __VA_ARGS__)
+#define E_kill(...) E_func(kill, __VA_ARGS__)
+#define E_mkdirat(...) E_func(mkdirat, __VA_ARGS__)
+#define E_mount(...) E_func(mount, __VA_ARGS__)
+#define E_prctl(...) E_func(prctl, __VA_ARGS__)
+#define E_readlink(...) E_func(readlink, __VA_ARGS__)
+#define E_setresuid(...) E_func(setresuid, __VA_ARGS__)
+#define E_symlinkat(...) E_func(symlinkat, __VA_ARGS__)
+#define E_touchat(...) E_func(touchat, __VA_ARGS__)
+#define E_unshare(...) E_func(unshare, __VA_ARGS__)
+
+#define E_assert(expr, msg, ...) \
+ do { \
+ if (!(expr)) \
+ ksft_exit_fail_msg("ASSERT(%s:%d) failed (%s): " msg "\n", \
+ __FILE__, __LINE__, #expr, ##__VA_ARGS__); \
+ } while (0)
+
+int raw_openat2(int dfd, const char *path, const void *how, size_t size);
+int sys_openat2(int dfd, const char *path, const struct open_how *how);
+int sys_openat(int dfd, const char *path, const struct open_how *how);
+int sys_renameat2(int olddirfd, const char *oldpath,
+ int newdirfd, const char *newpath, unsigned int flags);
+
+int touchat(int dfd, const char *path);
+char *fdreadlink(int fd);
+bool fdequal(int fd, int dfd, const char *path);
+
+void test_openat2_supported(void);
+
+#endif /* __RESOLVEAT_H__ */
new file mode 100644
@@ -0,0 +1,590 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Author: Aleksa Sarai <cyphar@cyphar.com>
+ * Copyright (C) 2018-2019 SUSE LLC.
+ */
+
+#define _GNU_SOURCE
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <sys/prctl.h>
+#include <sys/types.h>
+#include <sched.h>
+#include <stdbool.h>
+#include <signal.h>
+#include <string.h>
+
+#include "../kselftest.h"
+#include "helpers.h"
+
+static mode_t fdmode(int fd)
+{
+ char *fdpath;
+ struct stat statbuf;
+ mode_t mode;
+
+ E_asprintf(&fdpath, "/proc/self/fd/%d", fd);
+ E_fstatat(AT_FDCWD, fdpath, &statbuf, AT_SYMLINK_NOFOLLOW);
+ mode = (statbuf.st_mode & ~S_IFMT);
+ free(fdpath);
+
+ return mode;
+}
+
+static int reopen_proc(int fd, struct open_how how)
+{
+ int ret, saved_errno;
+ char *fdpath;
+
+ E_asprintf(&fdpath, "/proc/self/fd/%d", fd);
+ ret = sys_openat2(AT_FDCWD, fdpath, &how);
+ saved_errno = errno;
+ free(fdpath);
+
+ return ret >= 0 ? ret : -saved_errno;
+}
+
+static int reopen_oemptypath(int fd, struct open_how how)
+{
+ int ret;
+
+ how.flags |= O_EMPTYPATH;
+ ret = sys_openat2(fd, "", &how);
+ return ret >= 0 ? ret : -errno;
+}
+
+struct reopen_test {
+ const char *name, *srcpath;
+ bool openat2_only;
+ mode_t chmod_mode;
+ struct {
+ struct open_how how;
+ mode_t mode;
+ int err;
+ } orig, new;
+};
+
+static bool reopen(int fd, struct reopen_test *test)
+{
+ int newfd;
+ mode_t proc_mode;
+ bool failed = false;
+
+ /* Check that the proc mode is correct. */
+ proc_mode = fdmode(fd);
+ if (proc_mode != test->orig.mode) {
+ ksft_print_msg("incorrect fdmode (got[%o] != want[%o])\n",
+ proc_mode, test->orig.mode);
+ failed = true;
+ }
+
+ /* Re-open through /proc. */
+ newfd = reopen_proc(fd, test->new.how);
+ if (newfd != test->new.err && (newfd < 0 || test->new.err < 0)) {
+ ksft_print_msg("/proc failure (got[%d] != want[%d] [%s])\n",
+ newfd, test->new.err, strerror(-test->new.err));
+ failed = true;
+ }
+ if (newfd >= 0) {
+ proc_mode = fdmode(newfd);
+ if (proc_mode != test->new.mode) {
+ ksft_print_msg("/proc wrong fdmode (got[%o] != want[%o])\n",
+ proc_mode, test->new.mode);
+ failed = true;
+ }
+ close(newfd);
+ }
+
+ /* Re-open with O_EMPTYPATH -- but O_PATH is not supported. */
+ if (!(test->new.how.flags & O_PATH)) {
+ newfd = reopen_oemptypath(fd, test->new.how);
+ if (newfd != test->new.err && (newfd < 0 || test->new.err < 0)) {
+ ksft_print_msg("O_EMPTYPATH failure (got[%d] != want[%d] [%s])\n",
+ newfd, test->new.err, strerror(-test->new.err));
+ failed = true;
+ }
+ if (newfd >= 0) {
+ proc_mode = fdmode(newfd);
+ if (proc_mode != test->new.mode) {
+ ksft_print_msg("O_EMPTYPATH wrong fdmode (got[%o] != want[%o])\n",
+ proc_mode, test->new.mode);
+ failed = true;
+ }
+ close(newfd);
+ }
+ }
+
+ return failed;
+}
+
+#define NUM_REOPEN_ORDINARY_TESTS 44
+
+void test_reopen_ordinary(bool privileged)
+{
+ int fd;
+ int err_access = privileged ? 0 : -EACCES;
+ char tmpfile[] = "/tmp/ksft-openat2-reopen-testfile.XXXXXX";
+
+ fd = mkstemp(tmpfile);
+ E_assert(fd >= 0, "mkstemp failed: %m\n");
+ close(fd);
+
+ struct reopen_test tests[] = {
+ /* Re-opening with the same mode should succeed. */
+ { .name = "same mode (mode:r old:r new:r)",
+ .chmod_mode = 0400,
+ .orig.how.flags = O_RDONLY, .orig.mode = 0500,
+ .new.how.flags = O_RDONLY, .new.mode = 0500 },
+ { .name = "same mode (mode:w old:w new:w)",
+ .chmod_mode = 0200,
+ .orig.how.flags = O_WRONLY, .orig.mode = 0300,
+ .new.how.flags = O_WRONLY, .new.mode = 0300 },
+ { .name = "same mode (mode:rw old:rw new:rw)",
+ .chmod_mode = 0600,
+ .orig.how.flags = O_RDWR, .orig.mode = 0700,
+ .new.how.flags = O_RDWR, .new.mode = 0700 },
+ { .name = "same mode (mode:rw old:rw new:r)",
+ .chmod_mode = 0600,
+ .orig.how.flags = O_RDWR, .orig.mode = 0700,
+ .new.how.flags = O_RDONLY, .new.mode = 0500 },
+ { .name = "same mode (mode:rw old:rw new:w)",
+ .chmod_mode = 0600,
+ .orig.how.flags = O_RDWR, .orig.mode = 0700,
+ .new.how.flags = O_WRONLY, .new.mode = 0300 },
+
+ /*
+ * Re-opening with a different mode will always fail (with an obvious
+ * carve-out for privileged users).
+ */
+ { .name = "different mode (mode:rw old:r new:w)",
+ .chmod_mode = 0600,
+ .orig.how.flags = O_RDONLY, .orig.mode = 0500,
+ .new.how.flags = O_WRONLY, .new.mode = 0300, .new.err = err_access },
+ { .name = "different mode (mode:rw old:w new:r)",
+ .chmod_mode = 0600,
+ .orig.how.flags = O_WRONLY, .orig.mode = 0300,
+ .new.how.flags = O_RDONLY, .new.mode = 0500, .new.err = err_access },
+ { .name = "different mode (mode:rw old:r new:rw)",
+ .chmod_mode = 0600,
+ .orig.how.flags = O_RDONLY, .orig.mode = 0500,
+ .new.how.flags = O_RDWR, .new.mode = 0700, .new.err = err_access },
+ { .name = "different mode (mode:rw old:w new:rw)",
+ .chmod_mode = 0600,
+ .orig.how.flags = O_WRONLY, .orig.mode = 0300,
+ .new.how.flags = O_RDWR, .new.mode = 0700, .new.err = err_access },
+
+ /* Doubly so if they didn't even have permissions at open-time. */
+ { .name = "different mode (mode:r old:r new:w)",
+ .chmod_mode = 0400,
+ .orig.how.flags = O_RDONLY, .orig.mode = 0500,
+ .new.how.flags = O_WRONLY, .new.mode = 0300, .new.err = err_access },
+ { .name = "different mode (mode:w old:w new:r)",
+ .chmod_mode = 0200,
+ .orig.how.flags = O_WRONLY, .orig.mode = 0300,
+ .new.how.flags = O_RDONLY, .new.mode = 0500, .new.err = err_access },
+ { .name = "different mode (mode:r old:r new:rw)",
+ .chmod_mode = 0400,
+ .orig.how.flags = O_RDONLY, .orig.mode = 0500,
+ .new.how.flags = O_RDWR, .new.mode = 0700, .new.err = err_access },
+ { .name = "different mode (mode:w old:w new:rw)",
+ .chmod_mode = 0200,
+ .orig.how.flags = O_WRONLY, .orig.mode = 0300,
+ .new.how.flags = O_RDWR, .new.mode = 0700, .new.err = err_access },
+
+ /* O_PATH re-opens (of ordinary files) will always work. */
+ { .name = "O_PATH ordinary file (mode:_ old:RW new:w)",
+ .chmod_mode = 0000,
+ .orig.how.flags = O_PATH, .orig.mode = 0070,
+ .new.how.flags = O_WRONLY, .new.mode = 0300 },
+ { .name = "O_PATH ordinary file (mode:_ old:RW new:r)",
+ .chmod_mode = 0000,
+ .orig.how.flags = O_PATH, .orig.mode = 0070,
+ .new.how.flags = O_RDONLY, .new.mode = 0500 },
+ { .name = "O_PATH ordinary file (mode:_ old:RW new:rw)",
+ .chmod_mode = 0000,
+ .orig.how.flags = O_PATH, .orig.mode = 0070,
+ .new.how.flags = O_RDWR, .new.mode = 0700 },
+
+ /* O_PATH inherits the original magic-link mode. */
+ { .name = "O_PATH magic-link (mode:rw old:r new:R)",
+ .chmod_mode = 0600,
+ .orig.how.flags = O_RDONLY, .orig.mode = 0500,
+ .new.how.flags = O_PATH, .new.mode = 0050 },
+ { .name = "O_PATH magic-link (mode:rw old:w new:W)",
+ .chmod_mode = 0600,
+ .orig.how.flags = O_WRONLY, .orig.mode = 0300,
+ .new.how.flags = O_PATH, .new.mode = 0030 },
+ { .name = "O_PATH magic-link (mode:rw old:rw new:RW)",
+ .chmod_mode = 0600,
+ .orig.how.flags = O_RDWR, .orig.mode = 0700,
+ .new.how.flags = O_PATH, .new.mode = 0070 },
+
+ /*
+ * openat2(2) UPGRADE_NO* flags. In the privileged case, the re-open
+ * will work but the mode will still be scoped to the mode (or'd with
+ * the open acc_mode).
+ */
+ { .name = "O_PATH upgrade mask (mode:_ old:RW[-RW] new:r)",
+ .openat2_only = true, .chmod_mode = 0000,
+ .orig.how.flags = O_PATH, .orig.mode = 0010,
+ .orig.how.upgrade_mask = UPGRADE_NOREAD | UPGRADE_NOWRITE,
+ .new.how.flags = O_RDONLY, .new.mode = 0500, .new.err = err_access },
+ { .name = "O_PATH upgrade mask (mode:_ old:RW[-RW] new:w)",
+ .openat2_only = true, .chmod_mode = 0000,
+ .orig.how.flags = O_PATH, .orig.mode = 0010,
+ .orig.how.upgrade_mask = UPGRADE_NOREAD | UPGRADE_NOWRITE,
+ .new.how.flags = O_WRONLY, .new.mode = 0300, .new.err = err_access },
+ { .name = "O_PATH upgrade mask (mode:_ old:RW[-RW] new:rw)",
+ .openat2_only = true, .chmod_mode = 0000,
+ .orig.how.flags = O_PATH, .orig.mode = 0010,
+ .orig.how.upgrade_mask = UPGRADE_NOREAD | UPGRADE_NOWRITE,
+ .new.how.flags = O_RDWR, .new.mode = 0700, .new.err = err_access },
+
+ { .name = "O_PATH upgrade mask (mode:_ old:RW[-W] new:r)",
+ .openat2_only = true, .chmod_mode = 0000,
+ .orig.how.flags = O_PATH, .orig.mode = 0050,
+ .orig.how.upgrade_mask = UPGRADE_NOWRITE,
+ .new.how.flags = O_RDONLY, .new.mode = 0500 },
+
+ { .name = "O_PATH upgrade mask (mode:_ old:RW[-R] new:w)",
+ .openat2_only = true, .chmod_mode = 0000,
+ .orig.how.flags = O_PATH, .orig.mode = 0030,
+ .orig.how.upgrade_mask = UPGRADE_NOREAD,
+ .new.how.flags = O_WRONLY, .new.mode = 0300 },
+
+ { .name = "O_PATH upgrade mask (mode:_ old:RW[-R] new:r)",
+ .openat2_only = true, .chmod_mode = 0000,
+ .orig.how.flags = O_PATH, .orig.mode = 0030,
+ .orig.how.upgrade_mask = UPGRADE_NOREAD,
+ .new.how.flags = O_RDONLY, .new.mode = 0500, .new.err = err_access },
+ { .name = "O_PATH upgrade mask (mode:_ old:RW[-W] new:w)",
+ .openat2_only = true, .chmod_mode = 0000,
+ .orig.how.flags = O_PATH, .orig.mode = 0050,
+ .orig.how.upgrade_mask = UPGRADE_NOWRITE,
+ .new.how.flags = O_WRONLY, .new.mode = 0300, .new.err = err_access },
+ { .name = "O_PATH upgrade mask (mode:_ old:RW[-R] new:rw)",
+ .openat2_only = true, .chmod_mode = 0000,
+ .orig.how.flags = O_PATH, .orig.mode = 0030,
+ .orig.how.upgrade_mask = UPGRADE_NOREAD,
+ .new.how.flags = O_RDWR, .new.mode = 0700, .new.err = err_access },
+ { .name = "O_PATH upgrade mask (mode:_ old:RW[-W] new:rw)",
+ .openat2_only = true, .chmod_mode = 0000,
+ .orig.how.flags = O_PATH, .orig.mode = 0050,
+ .orig.how.upgrade_mask = UPGRADE_NOWRITE,
+ .new.how.flags = O_RDWR, .new.mode = 0700, .new.err = err_access },
+
+ /*
+ * O_PATH chained magic-links will inherit the limitations of
+ * the first magic-link.
+ *
+ * TODO: Really this should also be done with /proc/self/fd/.
+ */
+ { .name = "O_PATH chained magic-link of /proc/self/exe (old:R new:r)",
+ .srcpath = "/proc/self/exe",
+ .orig.how.flags = O_PATH, .orig.mode = 0050,
+ .new.how.flags = O_RDONLY, .new.mode = 0500 },
+ { .name = "O_PATH chained magic-link of /proc/self/exe (old:R new:R)",
+ .srcpath = "/proc/self/exe",
+ .orig.how.flags = O_PATH, .orig.mode = 0050,
+ .new.how.flags = O_PATH, .new.mode = 0050 },
+ { .name = "O_PATH chained magic-link of /proc/self/exe (old:R new:w)",
+ .srcpath = "/proc/self/exe",
+ .orig.how.flags = O_PATH, .orig.mode = 0050,
+ .new.how.flags = O_WRONLY, .new.err = err_access ?: -ETXTBSY },
+ { .name = "O_PATH chained magic-link of /proc/self/exe (old:R new:rw)",
+ .srcpath = "/proc/self/exe",
+ .orig.how.flags = O_PATH, .orig.mode = 0050,
+ .new.how.flags = O_RDWR, .new.err = err_access ?: -ETXTBSY },
+
+ /* O_PATH chained magic-links using UPGRADE_NO* flags. */
+ { .name = "O_PATH chained magic-link of /proc/self/exe (old:R new:R[-R])",
+ .srcpath = "/proc/self/exe",
+ .orig.how.flags = O_PATH, .orig.mode = 0050,
+ .new.how.flags = O_PATH, .new.mode = 0010,
+ .new.how.upgrade_mask = UPGRADE_NOREAD },
+ { .name = "O_PATH chained magic-link of /proc/self/exe (old:R[-R] new:_)",
+ .openat2_only = true, .srcpath = "/proc/self/exe",
+ .orig.how.flags = O_PATH, .orig.mode = 0010,
+ .orig.how.upgrade_mask = UPGRADE_NOREAD,
+ .new.how.flags = O_PATH, .new.mode = 0010},
+ { .name = "O_PATH chained magic-link of /proc/self/exe (old:R[-R] new:r)",
+ .openat2_only = true, .srcpath = "/proc/self/exe",
+ .orig.how.flags = O_PATH, .orig.mode = 0010,
+ .orig.how.upgrade_mask = UPGRADE_NOREAD,
+ .new.how.flags = O_RDONLY, .new.mode = 0500, .new.err = err_access },
+
+ { .name = "O_PATH chained magic-link (mode:_ old:RW new:RW)",
+ .chmod_mode = 0000,
+ .orig.how.flags = O_PATH, .orig.mode = 0070,
+ .new.how.flags = O_PATH, .new.mode = 0070 },
+ { .name = "O_PATH chained magic-link (mode:_ old:RW new:RW[-RW])",
+ .chmod_mode = 0000,
+ .orig.how.flags = O_PATH, .orig.mode = 0070,
+ .new.how.flags = O_PATH, .new.mode = 0010,
+ .new.how.upgrade_mask = UPGRADE_NOREAD | UPGRADE_NOWRITE },
+ { .name = "O_PATH chained magic-link (mode:_ old:RW new:RW[-R])",
+ .chmod_mode = 0000,
+ .orig.how.flags = O_PATH, .orig.mode = 0070,
+ .new.how.flags = O_PATH, .new.mode = 0030,
+ .new.how.upgrade_mask = UPGRADE_NOREAD },
+ { .name = "O_PATH chained magic-link (mode:_ old:RW new:RW[-W])",
+ .chmod_mode = 0000,
+ .orig.how.flags = O_PATH, .orig.mode = 0070,
+ .new.how.flags = O_PATH, .new.mode = 0050,
+ .new.how.upgrade_mask = UPGRADE_NOWRITE },
+
+ { .name = "O_PATH chained magic-link (mode:_ old:RW[-RW] new:_)",
+ .openat2_only = true, .chmod_mode = 0000,
+ .orig.how.flags = O_PATH, .orig.mode = 0010,
+ .orig.how.upgrade_mask = UPGRADE_NOREAD | UPGRADE_NOWRITE,
+ .new.how.flags = O_PATH, .new.mode = 0010 },
+
+ { .name = "O_PATH chained magic-link (mode:_ old:RW[-R] new:W)",
+ .openat2_only = true, .chmod_mode = 0000,
+ .orig.how.flags = O_PATH, .orig.mode = 0030,
+ .orig.how.upgrade_mask = UPGRADE_NOREAD,
+ .new.how.flags = O_PATH, .new.mode = 0030 },
+ { .name = "O_PATH chained magic-link (mode:_ old:RW[-R] new:W[-W])",
+ .openat2_only = true, .chmod_mode = 0000,
+ .orig.how.flags = O_PATH, .orig.mode = 0030,
+ .orig.how.upgrade_mask = UPGRADE_NOREAD,
+ .new.how.flags = O_PATH, .new.mode = 0010,
+ .new.how.upgrade_mask = UPGRADE_NOWRITE },
+
+ { .name = "O_PATH chained magic-link (mode:_ old:RW[-W] new:R)",
+ .openat2_only = true, .chmod_mode = 0000,
+ .orig.how.flags = O_PATH, .orig.mode = 0050,
+ .orig.how.upgrade_mask = UPGRADE_NOWRITE,
+ .new.how.flags = O_PATH, .new.mode = 0050 },
+ { .name = "O_PATH chained magic-link (mode:_ old:RW[-W] new:R[-R])",
+ .openat2_only = true, .chmod_mode = 0000,
+ .orig.how.flags = O_PATH, .orig.mode = 0050,
+ .orig.how.upgrade_mask = UPGRADE_NOWRITE,
+ .new.how.flags = O_PATH, .new.mode = 0010,
+ .new.how.upgrade_mask = UPGRADE_NOREAD },
+ };
+
+ BUILD_BUG_ON(ARRAY_LEN(tests) != NUM_REOPEN_ORDINARY_TESTS);
+
+ for (int i = 0; i < ARRAY_LEN(tests); i++) {
+ int fd;
+ const char *src = tmpfile;
+ struct reopen_test *test = &tests[i];
+ void (*resultfn)(const char *msg, ...) = ksft_test_result_pass;
+
+ if (test->srcpath)
+ src = test->srcpath;
+
+ if (test->openat2_only)
+ goto openat2;
+
+ if (src == tmpfile)
+ E_chmod(src, test->chmod_mode);
+ fd = sys_openat(AT_FDCWD, src, &test->orig.how);
+ E_assert(fd >= 0, "open '%s' failed: %m\n", src);
+ if (src == tmpfile)
+ E_chmod(src, 0700);
+
+ if (reopen(fd, test)) {
+ resultfn = ksft_test_result_fail;
+ ksft_print_msg("openat reopen failed\n");
+ }
+ close(fd);
+
+openat2:
+ if (src == tmpfile)
+ E_chmod(src, test->chmod_mode);
+ fd = sys_openat2(AT_FDCWD, src, &test->orig.how);
+ E_assert(fd >= 0, "open '%s' failed: %m\n", src);
+ if (src == tmpfile)
+ E_chmod(src, 0700);
+
+ if (reopen(fd, test)) {
+ resultfn = ksft_test_result_fail;
+ ksft_print_msg("openat2 reopen failed\n");
+ }
+ close(fd);
+
+ if (!test->new.err)
+ resultfn("%s%s %s succeeds\n",
+ privileged ? "privileged " : "",
+ test->openat2_only ? "openat2" : "openat(+2)",
+ test->name);
+ else
+ resultfn("%s%s %s fails with %d (%s)\n",
+ privileged ? "privileged " : "",
+ test->openat2_only ? "openat2" : "openat(+2)",
+ test->name, test->new.err,
+ strerror(-test->new.err));
+ fflush(stdout);
+ }
+
+ unlink(tmpfile);
+}
+
+#define NUM_FLIPFLOP_RACE_TESTS 2
+
+struct flipflop_test {
+ int target_fd, dummy_fd, attacker_fd;
+};
+
+int flipflopper(void *arg)
+{
+ struct flipflop_test *test = arg;
+
+ /* If the parent (the test process) dies, kill ourselves too. */
+ E_prctl(PR_SET_PDEATHSIG, SIGKILL);
+
+ for (;;) {
+ dup2(test->target_fd, test->attacker_fd);
+ dup2(test->dummy_fd, test->attacker_fd);
+ }
+
+ return 1;
+}
+
+#define FLIPFLOP_ROUNDS 500000
+#define STACK_SIZE (1024 * 1024)
+static char flipflop_stack[STACK_SIZE];
+
+void test_reopen_flipflop(void)
+{
+ pid_t child;
+ int procfs_failures = 0, emptypath_failures = 0;
+ struct flipflop_test test = {};
+ void (*resultfn)(const char *msg, ...) = ksft_test_result_pass;
+
+ int tmpfd;
+ char tmpfile[] = "/tmp/ksft-openat2-reopen-testfile.XXXXXX";
+
+ tmpfd = mkstemp(tmpfile);
+ E_assert(tmpfd >= 0, "mkstemp failed: %m\n");
+ close(tmpfd);
+
+ test.target_fd = open(tmpfile, O_RDONLY);
+ test.dummy_fd = open("/dev/null", O_RDWR);
+ /* Get an fd to target for the attack. */
+ test.attacker_fd = dup(test.dummy_fd);
+
+ /* We need to share our fdtable with the flipper. */
+ child = clone(flipflopper, flipflop_stack + STACK_SIZE,
+ CLONE_FILES, &test);
+ E_assert(child >= 0, "clone() failed: %m\n");
+
+ for (int i = 0; i < FLIPFLOP_ROUNDS; i++) {
+ int newfd;
+ struct open_how how = { .flags = O_WRONLY };
+
+ newfd = reopen_proc(test.attacker_fd, how);
+ if (newfd >= 0) {
+ /* Did we open the readonly-fd as O_WRONLY? */
+ if (fdequal(newfd, test.target_fd, NULL))
+ procfs_failures++;
+ close(newfd);
+ }
+
+ newfd = reopen_oemptypath(test.attacker_fd, how);
+ if (newfd >= 0) {
+ /* Did we open the readonly-fd as O_WRONLY? */
+ if (fdequal(newfd, test.target_fd, NULL))
+ emptypath_failures++;
+ close(newfd);
+ }
+ }
+
+ if (procfs_failures + emptypath_failures > 0) {
+ resultfn = ksft_test_result_fail;
+ ksft_print_msg("illegal re-opens: procfs=%d + O_EMPTYPATH=%d\n",
+ procfs_failures, emptypath_failures);
+ }
+ resultfn("flip-flop reopen attack (%d runs, got %d illegal re-opens)\n",
+ FLIPFLOP_ROUNDS, procfs_failures + emptypath_failures);
+
+ /* Should be killed anyway, but might as well make sure. */
+ E_kill(child, SIGKILL);
+}
+
+void test_xdev_flipflop(void)
+{
+ pid_t child;
+ int procfs_failures = 0;
+ struct flipflop_test test = {};
+ void (*resultfn)(const char *msg, ...) = ksft_test_result_pass;
+
+ int tmpfd;
+ char tmpfile[] = "/tmp/ksft-openat2-xdev-testfile.XXXXXX";
+
+ tmpfd = mkstemp(tmpfile);
+ E_assert(tmpfd >= 0, "mkstemp failed: %m\n");
+ close(tmpfd);
+
+ test.target_fd = open(tmpfile, O_RDONLY);
+ test.dummy_fd = open("/proc", O_RDONLY);
+ /* Get an fd to target for the attack. */
+ test.attacker_fd = dup(test.dummy_fd);
+
+ /* We need to share our fdtable with the flipper. */
+ child = clone(flipflopper, flipflop_stack + STACK_SIZE,
+ CLONE_FILES, &test);
+ E_assert(child >= 0, "clone() failed: %m\n");
+
+ for (int i = 0; i < FLIPFLOP_ROUNDS; i++) {
+ int newfd;
+ struct open_how how = {
+ .flags = O_RDONLY,
+ .resolve = RESOLVE_NO_XDEV,
+ };
+
+ newfd = reopen_proc(test.attacker_fd, how);
+ if (newfd >= 0) {
+ /* Did we open the readonly-fd as O_WRONLY? */
+ if (fdequal(newfd, test.target_fd, NULL))
+ procfs_failures++;
+ close(newfd);
+ }
+ }
+
+ if (procfs_failures > 0) {
+ resultfn = ksft_test_result_fail;
+ ksft_print_msg("illegal opens: procfs=%d\n", procfs_failures);
+ }
+ resultfn("flip-flop no_xdev attack (%d runs, got %d illegal opens)\n",
+ FLIPFLOP_ROUNDS, procfs_failures);
+
+ /* Should be killed anyway, but might as well make sure. */
+ E_kill(child, SIGKILL);
+}
+
+#define NUM_TESTS (2 * NUM_REOPEN_ORDINARY_TESTS) + NUM_FLIPFLOP_RACE_TESTS
+
+int main(int argc, char **argv)
+{
+ bool privileged;
+
+ ksft_print_header();
+ ksft_set_plan(NUM_TESTS);
+ test_openat2_supported();
+
+ /*
+ * Technically we should be checking CAP_DAC_OVERRIDE, but it's easier to
+ * just assume that euid=0 has the full capability set.
+ */
+ privileged = (geteuid() == 0);
+ if (!privileged)
+ ksft_test_result_skip("privileged tests require euid == 0\n");
+ else {
+ test_reopen_ordinary(privileged);
+
+ E_setresuid(65534, 65534, 65534);
+ privileged = (geteuid() == 0);
+ }
+
+ test_reopen_ordinary(privileged);
+ test_reopen_flipflop();
+ test_xdev_flipflop();
+
+ if (ksft_get_fail_cnt() + ksft_get_error_cnt() > 0)
+ ksft_exit_fail();
+ else
+ ksft_exit_pass();
+}
new file mode 100644
@@ -0,0 +1,152 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Author: Aleksa Sarai <cyphar@cyphar.com>
+ * Copyright (C) 2018-2019 SUSE LLC.
+ */
+
+#define _GNU_SOURCE
+#include <fcntl.h>
+#include <sched.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/mount.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+
+#include "../kselftest.h"
+#include "helpers.h"
+
+#define NUM_OPENAT2_TESTS 7
+#define NUM_OPENAT2_VARIATIONS 13
+
+struct open_how_ext {
+ struct open_how inner;
+ uint32_t extra1;
+ char pad1[128];
+ uint32_t extra2;
+ char pad2[128];
+ uint32_t extra3;
+};
+
+struct struct_test {
+ const char *name;
+ struct open_how_ext arg;
+ size_t size;
+ int err;
+};
+
+void test_openat2_struct(void)
+{
+ int misalignments[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 17, 87 };
+
+ struct struct_test tests[] = {
+ /* Normal struct. */
+ { .name = "normal struct",
+ .arg.inner.flags = O_RDONLY,
+ .size = sizeof(struct open_how) },
+ /* Bigger struct, with zeroed out end. */
+ { .name = "bigger struct (zeroed out)",
+ .arg.inner.flags = O_RDONLY,
+ .size = sizeof(struct open_how_ext) },
+
+ /* TODO: Once expanded, check zero-padding. */
+
+ /* Smaller than version-0 struct. */
+ { .name = "zero-sized 'struct'",
+ .arg.inner.flags = O_RDONLY, .size = 0, .err = -EINVAL },
+ { .name = "smaller-than-v0 struct",
+ .arg.inner.flags = O_RDONLY,
+ .size = OPEN_HOW_SIZE_VER0 - 1, .err = -EINVAL },
+
+ /* Bigger struct, with non-zero trailing bytes. */
+ { .name = "bigger struct (non-zero data in first 'future field')",
+ .arg.inner.flags = O_RDONLY, .arg.extra1 = 0xdeadbeef,
+ .size = sizeof(struct open_how_ext), .err = -E2BIG },
+ { .name = "bigger struct (non-zero data in middle of 'future fields')",
+ .arg.inner.flags = O_RDONLY, .arg.extra2 = 0xfeedcafe,
+ .size = sizeof(struct open_how_ext), .err = -E2BIG },
+ { .name = "bigger struct (non-zero data at end of 'future fields')",
+ .arg.inner.flags = O_RDONLY, .arg.extra3 = 0xabad1dea,
+ .size = sizeof(struct open_how_ext), .err = -E2BIG },
+ };
+
+ BUILD_BUG_ON(ARRAY_LEN(misalignments) != NUM_OPENAT2_VARIATIONS);
+ BUILD_BUG_ON(ARRAY_LEN(tests) != NUM_OPENAT2_TESTS);
+
+ for (int i = 0; i < ARRAY_LEN(tests); i++) {
+ struct struct_test *test = &tests[i];
+ struct open_how_ext how_ext = test->arg;
+
+ for (int j = 0; j < ARRAY_LEN(misalignments); j++) {
+ int fd, misalign = misalignments[j];
+ char *fdpath = NULL;
+ bool failed;
+ void (*resultfn)(const char *msg, ...) = ksft_test_result_pass;
+
+ void *copy = NULL, *how_copy = &how_ext;
+
+ if (misalign) {
+ /*
+ * Explicitly misalign the structure copying it with the given
+ * (mis)alignment offset. The other data is set to be non-zero to
+ * make sure that non-zero bytes outside the struct aren't checked
+ *
+ * This is effectively to check that is_zeroed_user() works.
+ */
+ copy = malloc(misalign + sizeof(how_ext));
+ how_copy = copy + misalign;
+ memset(copy, 0xff, misalign);
+ memcpy(how_copy, &how_ext, sizeof(how_ext));
+ }
+
+ fd = raw_openat2(AT_FDCWD, ".", how_copy, test->size);
+ if (test->err >= 0)
+ failed = (fd < 0);
+ else
+ failed = (fd != test->err);
+ if (fd >= 0) {
+ fdpath = fdreadlink(fd);
+ close(fd);
+ }
+
+ if (failed) {
+ resultfn = ksft_test_result_fail;
+
+ ksft_print_msg("openat2 unexpectedly returned ");
+ if (fdpath)
+ ksft_print_msg("%d['%s']\n", fd, fdpath);
+ else
+ ksft_print_msg("%d (%s)\n", fd, strerror(-fd));
+ }
+
+ if (test->err >= 0)
+ resultfn("openat2 with %s argument [misalign=%d] succeeds\n",
+ test->name, misalign);
+ else
+ resultfn("openat2 with %s argument [misalign=%d] fails with %d (%s)\n",
+ test->name, misalign, test->err,
+ strerror(-test->err));
+
+ free(copy);
+ free(fdpath);
+ fflush(stdout);
+ }
+ }
+}
+
+#define NUM_TESTS (NUM_OPENAT2_VARIATIONS * NUM_OPENAT2_TESTS)
+
+int main(int argc, char **argv)
+{
+ ksft_print_header();
+ ksft_set_plan(NUM_TESTS);
+
+ test_openat2_supported();
+ test_openat2_struct();
+
+ if (ksft_get_fail_cnt() + ksft_get_error_cnt() > 0)
+ ksft_exit_fail();
+ else
+ ksft_exit_pass();
+}
new file mode 100644
@@ -0,0 +1,149 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Author: Aleksa Sarai <cyphar@cyphar.com>
+ * Copyright (C) 2018-2019 SUSE LLC.
+ */
+
+#define _GNU_SOURCE
+#include <errno.h>
+#include <fcntl.h>
+#include <sched.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/mount.h>
+#include <sys/mman.h>
+#include <sys/prctl.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+#include <syscall.h>
+#include <limits.h>
+#include <unistd.h>
+
+#include "../kselftest.h"
+#include "helpers.h"
+
+/* Construct a test directory with the following structure:
+ *
+ * root/
+ * |-- a/
+ * | `-- c/
+ * `-- b/
+ */
+int setup_testdir(void)
+{
+ int dfd;
+ char dirname[] = "/tmp/ksft-openat2-rename-attack.XXXXXX";
+
+ /* Make the top-level directory. */
+ if (!mkdtemp(dirname))
+ ksft_exit_fail_msg("setup_testdir: failed to create tmpdir\n");
+ dfd = open(dirname, O_PATH | O_DIRECTORY);
+ if (dfd < 0)
+ ksft_exit_fail_msg("setup_testdir: failed to open tmpdir\n");
+
+ E_mkdirat(dfd, "a", 0755);
+ E_mkdirat(dfd, "b", 0755);
+ E_mkdirat(dfd, "a/c", 0755);
+
+ return dfd;
+}
+
+/* Swap @dirfd/@a and @dirfd/@b constantly. Parent must kill this process. */
+pid_t spawn_attack(int dirfd, char *a, char *b)
+{
+ pid_t child = fork();
+ if (child != 0)
+ return child;
+
+ /* If the parent (the test process) dies, kill ourselves too. */
+ E_prctl(PR_SET_PDEATHSIG, SIGKILL);
+
+ /* Swap @a and @b. */
+ for (;;)
+ renameat2(dirfd, a, dirfd, b, RENAME_EXCHANGE);
+ exit(1);
+}
+
+#define NUM_RENAME_TESTS 2
+#define ROUNDS 400000
+
+const char *flagname(int resolve)
+{
+ switch (resolve) {
+ case RESOLVE_IN_ROOT:
+ return "RESOLVE_IN_ROOT";
+ case RESOLVE_BENEATH:
+ return "RESOLVE_BENEATH";
+ }
+ return "(unknown)";
+}
+
+void test_rename_attack(int resolve)
+{
+ int dfd, afd;
+ pid_t child;
+ void (*resultfn)(const char *msg, ...) = ksft_test_result_pass;
+ int escapes = 0, other_errs = 0, exdevs = 0, eagains = 0, successes = 0;
+
+ dfd = setup_testdir();
+ afd = openat(dfd, "a", O_PATH);
+ if (afd < 0)
+ ksft_exit_fail_msg("test_rename_attack: failed to open 'a'\n");
+
+ child = spawn_attack(dfd, "a/c", "b");
+
+ for (int i = 0; i < ROUNDS; i++) {
+ int fd;
+ struct open_how how = {
+ .flags = O_PATH,
+ .resolve = resolve,
+ };
+ char *victim_path = "c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../..";
+
+ fd = sys_openat2(afd, victim_path, &how);
+ if (fd < 0) {
+ if (fd == -EAGAIN)
+ eagains++;
+ else if (fd == -EXDEV)
+ exdevs++;
+ else
+ other_errs++; /* unexpected error */
+ } else {
+ if (fdequal(fd, afd, NULL))
+ successes++;
+ else
+ escapes++; /* we got an unexpected fd */
+ }
+ close(fd);
+ }
+
+ if (escapes > 0)
+ resultfn = ksft_test_result_fail;
+ ksft_print_msg("non-escapes: EAGAIN=%d EXDEV=%d E<other>=%d success=%d\n",
+ eagains, exdevs, other_errs, successes);
+ resultfn("rename attack with %s (%d runs, got %d escapes)\n",
+ flagname(resolve), ROUNDS, escapes);
+
+ /* Should be killed anyway, but might as well make sure. */
+ E_kill(child, SIGKILL);
+}
+
+#define NUM_TESTS NUM_RENAME_TESTS
+
+int main(int argc, char **argv)
+{
+ ksft_print_header();
+ ksft_set_plan(NUM_TESTS);
+ test_openat2_supported();
+
+ test_rename_attack(RESOLVE_BENEATH);
+ test_rename_attack(RESOLVE_IN_ROOT);
+
+ if (ksft_get_fail_cnt() + ksft_get_error_cnt() > 0)
+ ksft_exit_fail();
+ else
+ ksft_exit_pass();
+}
new file mode 100644
@@ -0,0 +1,522 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Author: Aleksa Sarai <cyphar@cyphar.com>
+ * Copyright (C) 2018-2019 SUSE LLC.
+ */
+
+#define _GNU_SOURCE
+#include <fcntl.h>
+#include <sched.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/mount.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+
+#include "../kselftest.h"
+#include "helpers.h"
+
+/*
+ * Construct a test directory with the following structure:
+ *
+ * root/
+ * |-- procexe -> /proc/self/exe
+ * |-- procroot -> /proc/self/root
+ * |-- root/
+ * |-- mnt/ [mountpoint]
+ * | |-- self -> ../mnt/
+ * | `-- absself -> /mnt/
+ * |-- etc/
+ * | `-- passwd
+ * |-- creatlink -> /newfile3
+ * |-- reletc -> etc/
+ * |-- relsym -> etc/passwd
+ * |-- absetc -> /etc/
+ * |-- abssym -> /etc/passwd
+ * |-- abscheeky -> /cheeky
+ * `-- cheeky/
+ * |-- absself -> /
+ * |-- self -> ../../root/
+ * |-- garbageself -> /../../root/
+ * |-- passwd -> ../cheeky/../cheeky/../etc/../etc/passwd
+ * |-- abspasswd -> /../cheeky/../cheeky/../etc/../etc/passwd
+ * |-- dotdotlink -> ../../../../../../../../../../../../../../etc/passwd
+ * `-- garbagelink -> /../../../../../../../../../../../../../../etc/passwd
+ */
+int setup_testdir(void)
+{
+ int dfd, tmpfd;
+ char dirname[] = "/tmp/ksft-openat2-testdir.XXXXXX";
+
+ /* Unshare and make /tmp a new directory. */
+ E_unshare(CLONE_NEWNS);
+ E_mount("", "/tmp", "", MS_PRIVATE, "");
+
+ /* Make the top-level directory. */
+ if (!mkdtemp(dirname))
+ ksft_exit_fail_msg("setup_testdir: failed to create tmpdir\n");
+ dfd = open(dirname, O_PATH | O_DIRECTORY);
+ if (dfd < 0)
+ ksft_exit_fail_msg("setup_testdir: failed to open tmpdir\n");
+
+ /* A sub-directory which is actually used for tests. */
+ E_mkdirat(dfd, "root", 0755);
+ tmpfd = openat(dfd, "root", O_PATH | O_DIRECTORY);
+ if (tmpfd < 0)
+ ksft_exit_fail_msg("setup_testdir: failed to open tmpdir\n");
+ close(dfd);
+ dfd = tmpfd;
+
+ E_symlinkat("/proc/self/exe", dfd, "procexe");
+ E_symlinkat("/proc/self/root", dfd, "procroot");
+ E_mkdirat(dfd, "root", 0755);
+
+ /* There is no mountat(2), so use chdir. */
+ E_mkdirat(dfd, "mnt", 0755);
+ E_fchdir(dfd);
+ E_mount("tmpfs", "./mnt", "tmpfs", MS_NOSUID | MS_NODEV, "");
+ E_symlinkat("../mnt/", dfd, "mnt/self");
+ E_symlinkat("/mnt/", dfd, "mnt/absself");
+
+ E_mkdirat(dfd, "etc", 0755);
+ E_touchat(dfd, "etc/passwd");
+
+ E_symlinkat("/newfile3", dfd, "creatlink");
+ E_symlinkat("etc/", dfd, "reletc");
+ E_symlinkat("etc/passwd", dfd, "relsym");
+ E_symlinkat("/etc/", dfd, "absetc");
+ E_symlinkat("/etc/passwd", dfd, "abssym");
+ E_symlinkat("/cheeky", dfd, "abscheeky");
+
+ E_mkdirat(dfd, "cheeky", 0755);
+
+ E_symlinkat("/", dfd, "cheeky/absself");
+ E_symlinkat("../../root/", dfd, "cheeky/self");
+ E_symlinkat("/../../root/", dfd, "cheeky/garbageself");
+
+ E_symlinkat("../cheeky/../etc/../etc/passwd", dfd, "cheeky/passwd");
+ E_symlinkat("/../cheeky/../etc/../etc/passwd", dfd, "cheeky/abspasswd");
+
+ E_symlinkat("../../../../../../../../../../../../../../etc/passwd",
+ dfd, "cheeky/dotdotlink");
+ E_symlinkat("/../../../../../../../../../../../../../../etc/passwd",
+ dfd, "cheeky/garbagelink");
+
+ return dfd;
+}
+
+struct basic_test {
+ const char *name;
+ const char *dir;
+ const char *path;
+ struct open_how how;
+ bool pass;
+ union {
+ int err;
+ const char *path;
+ } out;
+};
+
+#define NUM_OPENAT2_OPATH_TESTS 88
+
+void test_openat2_opath_tests(void)
+{
+ int rootfd, hardcoded_fd;
+ char *procselfexe, *hardcoded_fdpath;
+
+ E_asprintf(&procselfexe, "/proc/%d/exe", getpid());
+ rootfd = setup_testdir();
+
+ hardcoded_fd = open("/dev/null", O_RDONLY);
+ E_assert(hardcoded_fd >= 0, "open fd to hardcode");
+ E_asprintf(&hardcoded_fdpath, "self/fd/%d", hardcoded_fd);
+
+ struct basic_test tests[] = {
+ /** RESOLVE_BENEATH **/
+ /* Attempts to cross dirfd should be blocked. */
+ { .name = "[beneath] jump to /",
+ .path = "/", .how.resolve = RESOLVE_BENEATH,
+ .out.err = -EXDEV, .pass = false },
+ { .name = "[beneath] absolute link to $root",
+ .path = "cheeky/absself", .how.resolve = RESOLVE_BENEATH,
+ .out.err = -EXDEV, .pass = false },
+ { .name = "[beneath] chained absolute links to $root",
+ .path = "abscheeky/absself", .how.resolve = RESOLVE_BENEATH,
+ .out.err = -EXDEV, .pass = false },
+ { .name = "[beneath] jump outside $root",
+ .path = "..", .how.resolve = RESOLVE_BENEATH,
+ .out.err = -EXDEV, .pass = false },
+ { .name = "[beneath] temporary jump outside $root",
+ .path = "../root/", .how.resolve = RESOLVE_BENEATH,
+ .out.err = -EXDEV, .pass = false },
+ { .name = "[beneath] symlink temporary jump outside $root",
+ .path = "cheeky/self", .how.resolve = RESOLVE_BENEATH,
+ .out.err = -EXDEV, .pass = false },
+ { .name = "[beneath] chained symlink temporary jump outside $root",
+ .path = "abscheeky/self", .how.resolve = RESOLVE_BENEATH,
+ .out.err = -EXDEV, .pass = false },
+ { .name = "[beneath] garbage links to $root",
+ .path = "cheeky/garbageself", .how.resolve = RESOLVE_BENEATH,
+ .out.err = -EXDEV, .pass = false },
+ { .name = "[beneath] chained garbage links to $root",
+ .path = "abscheeky/garbageself", .how.resolve = RESOLVE_BENEATH,
+ .out.err = -EXDEV, .pass = false },
+ /* Only relative paths that stay inside dirfd should work. */
+ { .name = "[beneath] ordinary path to 'root'",
+ .path = "root", .how.resolve = RESOLVE_BENEATH,
+ .out.path = "root", .pass = true },
+ { .name = "[beneath] ordinary path to 'etc'",
+ .path = "etc", .how.resolve = RESOLVE_BENEATH,
+ .out.path = "etc", .pass = true },
+ { .name = "[beneath] ordinary path to 'etc/passwd'",
+ .path = "etc/passwd", .how.resolve = RESOLVE_BENEATH,
+ .out.path = "etc/passwd", .pass = true },
+ { .name = "[beneath] relative symlink inside $root",
+ .path = "relsym", .how.resolve = RESOLVE_BENEATH,
+ .out.path = "etc/passwd", .pass = true },
+ { .name = "[beneath] chained-'..' relative symlink inside $root",
+ .path = "cheeky/passwd", .how.resolve = RESOLVE_BENEATH,
+ .out.path = "etc/passwd", .pass = true },
+ { .name = "[beneath] absolute symlink component outside $root",
+ .path = "abscheeky/passwd", .how.resolve = RESOLVE_BENEATH,
+ .out.err = -EXDEV, .pass = false },
+ { .name = "[beneath] absolute symlink target outside $root",
+ .path = "abssym", .how.resolve = RESOLVE_BENEATH,
+ .out.err = -EXDEV, .pass = false },
+ { .name = "[beneath] absolute path outside $root",
+ .path = "/etc/passwd", .how.resolve = RESOLVE_BENEATH,
+ .out.err = -EXDEV, .pass = false },
+ { .name = "[beneath] cheeky absolute path outside $root",
+ .path = "cheeky/abspasswd", .how.resolve = RESOLVE_BENEATH,
+ .out.err = -EXDEV, .pass = false },
+ { .name = "[beneath] chained cheeky absolute path outside $root",
+ .path = "abscheeky/abspasswd", .how.resolve = RESOLVE_BENEATH,
+ .out.err = -EXDEV, .pass = false },
+ /* Tricky paths should fail. */
+ { .name = "[beneath] tricky '..'-chained symlink outside $root",
+ .path = "cheeky/dotdotlink", .how.resolve = RESOLVE_BENEATH,
+ .out.err = -EXDEV, .pass = false },
+ { .name = "[beneath] tricky absolute + '..'-chained symlink outside $root",
+ .path = "abscheeky/dotdotlink", .how.resolve = RESOLVE_BENEATH,
+ .out.err = -EXDEV, .pass = false },
+ { .name = "[beneath] tricky garbage link outside $root",
+ .path = "cheeky/garbagelink", .how.resolve = RESOLVE_BENEATH,
+ .out.err = -EXDEV, .pass = false },
+ { .name = "[beneath] tricky absolute + garbage link outside $root",
+ .path = "abscheeky/garbagelink", .how.resolve = RESOLVE_BENEATH,
+ .out.err = -EXDEV, .pass = false },
+
+ /** RESOLVE_IN_ROOT **/
+ /* All attempts to cross the dirfd will be scoped-to-root. */
+ { .name = "[in_root] jump to /",
+ .path = "/", .how.resolve = RESOLVE_IN_ROOT,
+ .out.path = NULL, .pass = true },
+ { .name = "[in_root] absolute symlink to /root",
+ .path = "cheeky/absself", .how.resolve = RESOLVE_IN_ROOT,
+ .out.path = NULL, .pass = true },
+ { .name = "[in_root] chained absolute symlinks to /root",
+ .path = "abscheeky/absself", .how.resolve = RESOLVE_IN_ROOT,
+ .out.path = NULL, .pass = true },
+ { .name = "[in_root] '..' at root",
+ .path = "..", .how.resolve = RESOLVE_IN_ROOT,
+ .out.path = NULL, .pass = true },
+ { .name = "[in_root] '../root' at root",
+ .path = "../root/", .how.resolve = RESOLVE_IN_ROOT,
+ .out.path = "root", .pass = true },
+ { .name = "[in_root] relative symlink containing '..' above root",
+ .path = "cheeky/self", .how.resolve = RESOLVE_IN_ROOT,
+ .out.path = "root", .pass = true },
+ { .name = "[in_root] garbage link to /root",
+ .path = "cheeky/garbageself", .how.resolve = RESOLVE_IN_ROOT,
+ .out.path = "root", .pass = true },
+ { .name = "[in_root] chainged garbage links to /root",
+ .path = "abscheeky/garbageself", .how.resolve = RESOLVE_IN_ROOT,
+ .out.path = "root", .pass = true },
+ { .name = "[in_root] relative path to 'root'",
+ .path = "root", .how.resolve = RESOLVE_IN_ROOT,
+ .out.path = "root", .pass = true },
+ { .name = "[in_root] relative path to 'etc'",
+ .path = "etc", .how.resolve = RESOLVE_IN_ROOT,
+ .out.path = "etc", .pass = true },
+ { .name = "[in_root] relative path to 'etc/passwd'",
+ .path = "etc/passwd", .how.resolve = RESOLVE_IN_ROOT,
+ .out.path = "etc/passwd", .pass = true },
+ { .name = "[in_root] relative symlink to 'etc/passwd'",
+ .path = "relsym", .how.resolve = RESOLVE_IN_ROOT,
+ .out.path = "etc/passwd", .pass = true },
+ { .name = "[in_root] chained-'..' relative symlink to 'etc/passwd'",
+ .path = "cheeky/passwd", .how.resolve = RESOLVE_IN_ROOT,
+ .out.path = "etc/passwd", .pass = true },
+ { .name = "[in_root] chained-'..' absolute + relative symlink to 'etc/passwd'",
+ .path = "abscheeky/passwd", .how.resolve = RESOLVE_IN_ROOT,
+ .out.path = "etc/passwd", .pass = true },
+ { .name = "[in_root] absolute symlink to 'etc/passwd'",
+ .path = "abssym", .how.resolve = RESOLVE_IN_ROOT,
+ .out.path = "etc/passwd", .pass = true },
+ { .name = "[in_root] absolute path 'etc/passwd'",
+ .path = "/etc/passwd", .how.resolve = RESOLVE_IN_ROOT,
+ .out.path = "etc/passwd", .pass = true },
+ { .name = "[in_root] cheeky absolute path 'etc/passwd'",
+ .path = "cheeky/abspasswd", .how.resolve = RESOLVE_IN_ROOT,
+ .out.path = "etc/passwd", .pass = true },
+ { .name = "[in_root] chained cheeky absolute path 'etc/passwd'",
+ .path = "abscheeky/abspasswd", .how.resolve = RESOLVE_IN_ROOT,
+ .out.path = "etc/passwd", .pass = true },
+ { .name = "[in_root] tricky '..'-chained symlink outside $root",
+ .path = "cheeky/dotdotlink", .how.resolve = RESOLVE_IN_ROOT,
+ .out.path = "etc/passwd", .pass = true },
+ { .name = "[in_root] tricky absolute + '..'-chained symlink outside $root",
+ .path = "abscheeky/dotdotlink", .how.resolve = RESOLVE_IN_ROOT,
+ .out.path = "etc/passwd", .pass = true },
+ { .name = "[in_root] tricky absolute path + absolute + '..'-chained symlink outside $root",
+ .path = "/../../../../abscheeky/dotdotlink", .how.resolve = RESOLVE_IN_ROOT,
+ .out.path = "etc/passwd", .pass = true },
+ { .name = "[in_root] tricky garbage link outside $root",
+ .path = "cheeky/garbagelink", .how.resolve = RESOLVE_IN_ROOT,
+ .out.path = "etc/passwd", .pass = true },
+ { .name = "[in_root] tricky absolute + garbage link outside $root",
+ .path = "abscheeky/garbagelink", .how.resolve = RESOLVE_IN_ROOT,
+ .out.path = "etc/passwd", .pass = true },
+ { .name = "[in_root] tricky absolute path + absolute + garbage link outside $root",
+ .path = "/../../../../abscheeky/garbagelink", .how.resolve = RESOLVE_IN_ROOT,
+ .out.path = "etc/passwd", .pass = true },
+ /* O_CREAT should handle trailing symlinks correctly. */
+ { .name = "[in_root] O_CREAT of relative path inside $root",
+ .path = "newfile1", .how.flags = O_CREAT,
+ .how.mode = 0700,
+ .how.resolve = RESOLVE_IN_ROOT,
+ .out.path = "newfile1", .pass = true },
+ { .name = "[in_root] O_CREAT of absolute path",
+ .path = "/newfile2", .how.flags = O_CREAT,
+ .how.mode = 0700,
+ .how.resolve = RESOLVE_IN_ROOT,
+ .out.path = "newfile2", .pass = true },
+ { .name = "[in_root] O_CREAT of tricky symlink outside root",
+ .path = "/creatlink", .how.flags = O_CREAT,
+ .how.mode = 0700,
+ .how.resolve = RESOLVE_IN_ROOT,
+ .out.path = "newfile3", .pass = true },
+
+ /** RESOLVE_NO_XDEV **/
+ /* Crossing *down* into a mountpoint is disallowed. */
+ { .name = "[no_xdev] cross into $mnt",
+ .path = "mnt", .how.resolve = RESOLVE_NO_XDEV,
+ .out.err = -EXDEV, .pass = false },
+ { .name = "[no_xdev] cross into $mnt/",
+ .path = "mnt/", .how.resolve = RESOLVE_NO_XDEV,
+ .out.err = -EXDEV, .pass = false },
+ { .name = "[no_xdev] cross into $mnt/.",
+ .path = "mnt/.", .how.resolve = RESOLVE_NO_XDEV,
+ .out.err = -EXDEV, .pass = false },
+ /* Crossing *up* out of a mountpoint is disallowed. */
+ { .name = "[no_xdev] goto mountpoint root",
+ .dir = "mnt", .path = ".", .how.resolve = RESOLVE_NO_XDEV,
+ .out.path = "mnt", .pass = true },
+ { .name = "[no_xdev] cross up through '..'",
+ .dir = "mnt", .path = "..", .how.resolve = RESOLVE_NO_XDEV,
+ .out.err = -EXDEV, .pass = false },
+ { .name = "[no_xdev] temporary cross up through '..'",
+ .dir = "mnt", .path = "../mnt", .how.resolve = RESOLVE_NO_XDEV,
+ .out.err = -EXDEV, .pass = false },
+ { .name = "[no_xdev] temporary relative symlink cross up",
+ .dir = "mnt", .path = "self", .how.resolve = RESOLVE_NO_XDEV,
+ .out.err = -EXDEV, .pass = false },
+ { .name = "[no_xdev] temporary absolute symlink cross up",
+ .dir = "mnt", .path = "absself", .how.resolve = RESOLVE_NO_XDEV,
+ .out.err = -EXDEV, .pass = false },
+ /* Jumping to "/" is ok, but later components cannot cross. */
+ { .name = "[no_xdev] jump to / directly",
+ .dir = "mnt", .path = "/", .how.resolve = RESOLVE_NO_XDEV,
+ .out.path = "/", .pass = true },
+ { .name = "[no_xdev] jump to / (from /) directly",
+ .dir = "/", .path = "/", .how.resolve = RESOLVE_NO_XDEV,
+ .out.path = "/", .pass = true },
+ { .name = "[no_xdev] jump to / then proc",
+ .path = "/proc/1", .how.resolve = RESOLVE_NO_XDEV,
+ .out.err = -EXDEV, .pass = false },
+ { .name = "[no_xdev] jump to / then tmp",
+ .path = "/tmp", .how.resolve = RESOLVE_NO_XDEV,
+ .out.err = -EXDEV, .pass = false },
+ /* Magic-links are blocked since they can switch vfsmounts. */
+ { .name = "[no_xdev] cross through magic-link to self/root",
+ .dir = "/proc", .path = "self/root", .how.resolve = RESOLVE_NO_XDEV,
+ .out.err = -EXDEV, .pass = false },
+ { .name = "[no_xdev] cross through magic-link to self/cwd",
+ .dir = "/proc", .path = "self/cwd", .how.resolve = RESOLVE_NO_XDEV,
+ .out.err = -EXDEV, .pass = false },
+ /* Except magic-link jumps inside the same vfsmount. */
+ { .name = "[no_xdev] jump through magic-link to same procfs",
+ .dir = "/proc", .path = hardcoded_fdpath, .how.resolve = RESOLVE_NO_XDEV,
+ .out.path = "/proc", .pass = true, },
+
+ /** RESOLVE_NO_MAGICLINKS **/
+ /* Regular symlinks should work. */
+ { .name = "[no_magiclinks] ordinary relative symlink",
+ .path = "relsym", .how.resolve = RESOLVE_NO_MAGICLINKS,
+ .out.path = "etc/passwd", .pass = true },
+ /* Magic-links should not work. */
+ { .name = "[no_magiclinks] symlink to magic-link",
+ .path = "procexe", .how.resolve = RESOLVE_NO_MAGICLINKS,
+ .out.err = -ELOOP, .pass = false },
+ { .name = "[no_magiclinks] normal path to magic-link",
+ .path = "/proc/self/exe", .how.resolve = RESOLVE_NO_MAGICLINKS,
+ .out.err = -ELOOP, .pass = false },
+ { .name = "[no_magiclinks] normal path to magic-link with O_NOFOLLOW",
+ .path = "/proc/self/exe", .how.flags = O_NOFOLLOW,
+ .how.resolve = RESOLVE_NO_MAGICLINKS,
+ .out.path = procselfexe, .pass = true },
+ { .name = "[no_magiclinks] symlink to magic-link path component",
+ .path = "procroot/etc", .how.resolve = RESOLVE_NO_MAGICLINKS,
+ .out.err = -ELOOP, .pass = false },
+ { .name = "[no_magiclinks] magic-link path component",
+ .path = "/proc/self/root/etc", .how.resolve = RESOLVE_NO_MAGICLINKS,
+ .out.err = -ELOOP, .pass = false },
+ { .name = "[no_magiclinks] magic-link path component with O_NOFOLLOW",
+ .path = "/proc/self/root/etc", .how.flags = O_NOFOLLOW,
+ .how.resolve = RESOLVE_NO_MAGICLINKS,
+ .out.err = -ELOOP, .pass = false },
+
+ /** RESOLVE_NO_SYMLINKS **/
+ /* Normal paths should work. */
+ { .name = "[no_symlinks] ordinary path to '.'",
+ .path = ".", .how.resolve = RESOLVE_NO_SYMLINKS,
+ .out.path = NULL, .pass = true },
+ { .name = "[no_symlinks] ordinary path to 'root'",
+ .path = "root", .how.resolve = RESOLVE_NO_SYMLINKS,
+ .out.path = "root", .pass = true },
+ { .name = "[no_symlinks] ordinary path to 'etc'",
+ .path = "etc", .how.resolve = RESOLVE_NO_SYMLINKS,
+ .out.path = "etc", .pass = true },
+ { .name = "[no_symlinks] ordinary path to 'etc/passwd'",
+ .path = "etc/passwd", .how.resolve = RESOLVE_NO_SYMLINKS,
+ .out.path = "etc/passwd", .pass = true },
+ /* Regular symlinks are blocked. */
+ { .name = "[no_symlinks] relative symlink target",
+ .path = "relsym", .how.resolve = RESOLVE_NO_SYMLINKS,
+ .out.err = -ELOOP, .pass = false },
+ { .name = "[no_symlinks] relative symlink component",
+ .path = "reletc/passwd", .how.resolve = RESOLVE_NO_SYMLINKS,
+ .out.err = -ELOOP, .pass = false },
+ { .name = "[no_symlinks] absolute symlink target",
+ .path = "abssym", .how.resolve = RESOLVE_NO_SYMLINKS,
+ .out.err = -ELOOP, .pass = false },
+ { .name = "[no_symlinks] absolute symlink component",
+ .path = "absetc/passwd", .how.resolve = RESOLVE_NO_SYMLINKS,
+ .out.err = -ELOOP, .pass = false },
+ { .name = "[no_symlinks] cheeky garbage link",
+ .path = "cheeky/garbagelink", .how.resolve = RESOLVE_NO_SYMLINKS,
+ .out.err = -ELOOP, .pass = false },
+ { .name = "[no_symlinks] cheeky absolute + garbage link",
+ .path = "abscheeky/garbagelink", .how.resolve = RESOLVE_NO_SYMLINKS,
+ .out.err = -ELOOP, .pass = false },
+ { .name = "[no_symlinks] cheeky absolute + absolute symlink",
+ .path = "abscheeky/absself", .how.resolve = RESOLVE_NO_SYMLINKS,
+ .out.err = -ELOOP, .pass = false },
+ /* Trailing symlinks with NO_FOLLOW. */
+ { .name = "[no_symlinks] relative symlink with O_NOFOLLOW",
+ .path = "relsym", .how.flags = O_NOFOLLOW,
+ .how.resolve = RESOLVE_NO_SYMLINKS,
+ .out.path = "relsym", .pass = true },
+ { .name = "[no_symlinks] absolute symlink with O_NOFOLLOW",
+ .path = "abssym", .how.flags = O_NOFOLLOW,
+ .how.resolve = RESOLVE_NO_SYMLINKS,
+ .out.path = "abssym", .pass = true },
+ { .name = "[no_symlinks] trailing symlink with O_NOFOLLOW",
+ .path = "cheeky/garbagelink", .how.flags = O_NOFOLLOW,
+ .how.resolve = RESOLVE_NO_SYMLINKS,
+ .out.path = "cheeky/garbagelink", .pass = true },
+ { .name = "[no_symlinks] multiple symlink components with O_NOFOLLOW",
+ .path = "abscheeky/absself", .how.flags = O_NOFOLLOW,
+ .how.resolve = RESOLVE_NO_SYMLINKS,
+ .out.err = -ELOOP, .pass = false },
+ { .name = "[no_symlinks] multiple symlink (and garbage link) components with O_NOFOLLOW",
+ .path = "abscheeky/garbagelink", .how.flags = O_NOFOLLOW,
+ .how.resolve = RESOLVE_NO_SYMLINKS,
+ .out.err = -ELOOP, .pass = false },
+ };
+
+ BUILD_BUG_ON(ARRAY_LEN(tests) != NUM_OPENAT2_OPATH_TESTS);
+
+ for (int i = 0; i < ARRAY_LEN(tests); i++) {
+ int dfd, fd;
+ char *fdpath = NULL;
+ bool failed;
+ void (*resultfn)(const char *msg, ...) = ksft_test_result_pass;
+ struct basic_test *test = &tests[i];
+
+ /* Auto-set O_PATH. */
+ if (!(test->how.flags & O_CREAT))
+ test->how.flags |= O_PATH;
+
+ if (test->dir)
+ dfd = openat(rootfd, test->dir, O_PATH | O_DIRECTORY);
+ else
+ dfd = dup(rootfd);
+ if (dfd < 0) {
+ resultfn = ksft_test_result_error;
+ ksft_print_msg("failed to openat root: %m");
+ goto next;
+ }
+
+ E_dup2(dfd, hardcoded_fd);
+
+ fd = sys_openat2(dfd, test->path, &test->how);
+ if (test->pass)
+ failed = (fd < 0 || !fdequal(fd, rootfd, test->out.path));
+ else
+ failed = (fd != test->out.err);
+ if (fd >= 0) {
+ fdpath = fdreadlink(fd);
+ close(fd);
+ }
+ close(dfd);
+
+ if (failed) {
+ resultfn = ksft_test_result_fail;
+
+ ksft_print_msg("openat2 unexpectedly returned ");
+ if (fdpath)
+ ksft_print_msg("%d['%s']\n", fd, fdpath);
+ else
+ ksft_print_msg("%d (%s)\n", fd, strerror(-fd));
+ }
+
+next:
+ if (test->pass)
+ resultfn("%s gives path '%s'\n", test->name,
+ test->out.path ?: ".");
+ else
+ resultfn("%s fails with %d (%s)\n", test->name,
+ test->out.err, strerror(-test->out.err));
+
+ fflush(stdout);
+ free(fdpath);
+ }
+
+ free(procselfexe);
+ close(rootfd);
+
+ free(hardcoded_fdpath);
+ close(hardcoded_fd);
+}
+
+#define NUM_TESTS NUM_OPENAT2_OPATH_TESTS
+
+int main(int argc, char **argv)
+{
+ ksft_print_header();
+ ksft_set_plan(NUM_TESTS);
+ test_openat2_supported();
+
+ /* NOTE: We should be checking for CAP_SYS_ADMIN here... */
+ if (geteuid() != 0)
+ ksft_exit_skip("openat2(2) tests require euid == 0\n");
+
+ test_openat2_opath_tests();
+
+ if (ksft_get_fail_cnt() + ksft_get_error_cnt() > 0)
+ ksft_exit_fail();
+ else
+ ksft_exit_pass();
+}
Test all of the various openat2(2) flags, as well as how file descriptor re-opening works. A small stress-test of a symlink-rename attack is included to show that the protections against ".."-based attacks are sufficient. In addition, the memfd selftest is fixed to no longer depend on the now-disallowed functionality of upgrading an O_RDONLY descriptor to O_RDWR. The main things these self-tests are enforcing are: * The struct+usize ABI for openat2(2) and copy_struct_from_user() to ensure that upgrades will be handled gracefully (in addition, ensuring that misaligned structures are also handled correctly). * All of the RESOLVE_* semantics (including errno values) are correctly handled with various combinations of paths and flags. * RESOLVE_IN_ROOT correctly protects against the symlink rename(2) attack that has been responsible for several CVEs (and likely will be responsible for several more). * The magic-link trailing mode semantics correctly block re-opens in all of the relevant cases, as well as checking that the "flip-flop" attack is correctly protected against. * O_PATH has the correct semantics (the mode is g+rwx for ordinary files, but for trailing magic-links the mode gets inherited). Signed-off-by: Aleksa Sarai <cyphar@cyphar.com> --- tools/testing/selftests/Makefile | 1 + tools/testing/selftests/memfd/memfd_test.c | 7 +- tools/testing/selftests/openat2/.gitignore | 1 + tools/testing/selftests/openat2/Makefile | 8 + tools/testing/selftests/openat2/helpers.c | 98 +++ tools/testing/selftests/openat2/helpers.h | 114 ++++ .../testing/selftests/openat2/linkmode_test.c | 590 ++++++++++++++++++ .../testing/selftests/openat2/openat2_test.c | 152 +++++ .../selftests/openat2/rename_attack_test.c | 149 +++++ .../testing/selftests/openat2/resolve_test.c | 522 ++++++++++++++++ 10 files changed, 1640 insertions(+), 2 deletions(-) create mode 100644 tools/testing/selftests/openat2/.gitignore create mode 100644 tools/testing/selftests/openat2/Makefile create mode 100644 tools/testing/selftests/openat2/helpers.c create mode 100644 tools/testing/selftests/openat2/helpers.h create mode 100644 tools/testing/selftests/openat2/linkmode_test.c create mode 100644 tools/testing/selftests/openat2/openat2_test.c create mode 100644 tools/testing/selftests/openat2/rename_attack_test.c create mode 100644 tools/testing/selftests/openat2/resolve_test.c