Test all of the various openat2(2) flags. A small stress-test of a symlink-rename attack is included to show that the protections against ".."-based attacks are sufficient.
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).
* The -EINVAL checks for openat2(2) are all correctly handled to avoid userspace passing unknown or conflicting flag sets (most importantly, ensuring that invalid flag combinations are checked).
* 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).
Cc: Shuah Khan shuah@kernel.org Signed-off-by: Aleksa Sarai cyphar@cyphar.com --- tools/testing/selftests/Makefile | 1 + tools/testing/selftests/openat2/.gitignore | 1 + tools/testing/selftests/openat2/Makefile | 8 + tools/testing/selftests/openat2/helpers.c | 109 ++++ tools/testing/selftests/openat2/helpers.h | 107 ++++ .../testing/selftests/openat2/openat2_test.c | 320 +++++++++++ .../selftests/openat2/rename_attack_test.c | 160 ++++++ .../testing/selftests/openat2/resolve_test.c | 523 ++++++++++++++++++ 8 files changed, 1229 insertions(+) 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/openat2_test.c create mode 100644 tools/testing/selftests/openat2/rename_attack_test.c create mode 100644 tools/testing/selftests/openat2/resolve_test.c
diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile index 4cdbae6f4e61..28996856ed5e 100644 --- a/tools/testing/selftests/Makefile +++ b/tools/testing/selftests/Makefile @@ -37,6 +37,7 @@ TARGETS += powerpc TARGETS += proc TARGETS += pstore TARGETS += ptrace +TARGETS += openat2 TARGETS += rseq TARGETS += rtc TARGETS += seccomp diff --git a/tools/testing/selftests/openat2/.gitignore b/tools/testing/selftests/openat2/.gitignore new file mode 100644 index 000000000000..bd68f6c3fd07 --- /dev/null +++ b/tools/testing/selftests/openat2/.gitignore @@ -0,0 +1 @@ +/*_test diff --git a/tools/testing/selftests/openat2/Makefile b/tools/testing/selftests/openat2/Makefile new file mode 100644 index 000000000000..4b93b1417b86 --- /dev/null +++ b/tools/testing/selftests/openat2/Makefile @@ -0,0 +1,8 @@ +# SPDX-License-Identifier: GPL-2.0-or-later + +CFLAGS += -Wall -O2 -g -fsanitize=address -fsanitize=undefined +TEST_GEN_PROGS := openat2_test resolve_test rename_attack_test + +include ../lib.mk + +$(TEST_GEN_PROGS): helpers.c diff --git a/tools/testing/selftests/openat2/helpers.c b/tools/testing/selftests/openat2/helpers.c new file mode 100644 index 000000000000..e9a6557ab16f --- /dev/null +++ b/tools/testing/selftests/openat2/helpers.c @@ -0,0 +1,109 @@ +// 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" + +bool needs_openat2(const struct open_how *how) +{ + return how->resolve != 0; +} + +int raw_openat2(int dfd, const char *path, 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, struct open_how *how) +{ + return raw_openat2(dfd, path, how, sizeof(*how)); +} + +int sys_openat(int dfd, const char *path, 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; +} + +bool openat2_supported = false; + +void __attribute__((constructor)) init(void) +{ + struct open_how how = {}; + int fd; + + BUILD_BUG_ON(sizeof(struct open_how) != OPEN_HOW_SIZE_VER0); + + /* Check openat2(2) support. */ + fd = sys_openat2(AT_FDCWD, ".", &how); + openat2_supported = (fd >= 0); + + if (fd >= 0) + close(fd); +} diff --git a/tools/testing/selftests/openat2/helpers.h b/tools/testing/selftests/openat2/helpers.h new file mode 100644 index 000000000000..43ca5ceab6e3 --- /dev/null +++ b/tools/testing/selftests/openat2/helpers.h @@ -0,0 +1,107 @@ +// 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 <linux/types.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 @resolve is + * zero, then openat2(2) operates very similarly to openat(2). + * + * However, unlike openat(2), unknown bits in @flags result in -EINVAL rather + * than being silently ignored. @mode must be zero unless one of {O_CREAT, + * O_TMPFILE} are set. + * + * @flags: O_* flags. + * @mode: O_CREAT/O_TMPFILE file mode. + * @resolve: RESOLVE_* flags. + */ +struct open_how { + __aligned_u64 flags; + __u16 mode; + __u16 __padding[3]; /* must be zeroed */ + __aligned_u64 resolve; +}; + +#define OPEN_HOW_SIZE_VER0 24 /* sizeof first published struct */ +#define OPEN_HOW_SIZE_LATEST OPEN_HOW_SIZE_VER0 + +bool needs_openat2(const struct open_how *how); + +#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 */ + +#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, void *how, size_t size); +int sys_openat2(int dfd, const char *path, struct open_how *how); +int sys_openat(int dfd, const char *path, 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); + +extern bool openat2_supported; + +#endif /* __RESOLVEAT_H__ */ diff --git a/tools/testing/selftests/openat2/openat2_test.c b/tools/testing/selftests/openat2/openat2_test.c new file mode 100644 index 000000000000..0b64fedc008b --- /dev/null +++ b/tools/testing/selftests/openat2/openat2_test.c @@ -0,0 +1,320 @@ +// 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" + +/* + * O_LARGEFILE is set to 0 by glibc. + * XXX: This is wrong on {mips, parisc, powerpc, sparc}. + */ +#undef O_LARGEFILE +#define O_LARGEFILE 0x8000 + +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; +}; + +#define NUM_OPENAT2_STRUCT_TESTS 10 +#define NUM_OPENAT2_STRUCT_VARIATIONS 13 + +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) }, + + /* Normal struct with broken padding. */ + { .name = "normal struct (non-zero padding[0])", + .arg.inner.flags = O_RDONLY, + .arg.inner.__padding = {0xa0, 0x00, 0x00}, + .size = sizeof(struct open_how_ext), .err = -EINVAL }, + { .name = "normal struct (non-zero padding[1])", + .arg.inner.flags = O_RDONLY, + .arg.inner.__padding = {0x00, 0x1a, 0x00}, + .size = sizeof(struct open_how_ext), .err = -EINVAL }, + { .name = "normal struct (non-zero padding[2])", + .arg.inner.flags = O_RDONLY, + .arg.inner.__padding = {0x00, 0x00, 0xef}, + .size = sizeof(struct open_how_ext), .err = -EINVAL }, + + /* 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_STRUCT_VARIATIONS); + BUILD_BUG_ON(ARRAY_LEN(tests) != NUM_OPENAT2_STRUCT_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 (!openat2_supported) { + ksft_print_msg("openat2(2) unsupported\n"); + resultfn = ksft_test_result_skip; + goto skip; + } + + 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)); + } + +skip: + 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); + } + } +} + +struct flag_test { + const char *name; + struct open_how how; + int err; +}; + +#define NUM_OPENAT2_FLAG_TESTS 21 + +void test_openat2_flags(void) +{ + struct flag_test tests[] = { + /* O_TMPFILE is incompatible with O_PATH and O_CREAT. */ + { .name = "incompatible flags (O_TMPFILE | O_PATH)", + .how.flags = O_TMPFILE | O_PATH | O_RDWR, .err = -EINVAL }, + { .name = "incompatible flags (O_TMPFILE | O_CREAT)", + .how.flags = O_TMPFILE | O_CREAT | O_RDWR, .err = -EINVAL }, + + /* O_PATH only permits certain other flags to be set ... */ + { .name = "compatible flags (O_PATH | O_CLOEXEC)", + .how.flags = O_PATH | O_CLOEXEC }, + { .name = "compatible flags (O_PATH | O_DIRECTORY)", + .how.flags = O_PATH | O_DIRECTORY }, + { .name = "compatible flags (O_PATH | O_NOFOLLOW)", + .how.flags = O_PATH | O_NOFOLLOW }, + /* ... and others are absolutely not permitted. */ + { .name = "incompatible flags (O_PATH | O_RDWR)", + .how.flags = O_PATH | O_RDWR, .err = -EINVAL }, + { .name = "incompatible flags (O_PATH | O_CREAT)", + .how.flags = O_PATH | O_CREAT, .err = -EINVAL }, + { .name = "incompatible flags (O_PATH | O_EXCL)", + .how.flags = O_PATH | O_EXCL, .err = -EINVAL }, + { .name = "incompatible flags (O_PATH | O_NOCTTY)", + .how.flags = O_PATH | O_NOCTTY, .err = -EINVAL }, + { .name = "incompatible flags (O_PATH | O_DIRECT)", + .how.flags = O_PATH | O_DIRECT, .err = -EINVAL }, + { .name = "incompatible flags (O_PATH | O_LARGEFILE)", + .how.flags = O_PATH | O_LARGEFILE, .err = -EINVAL }, + + /* ->mode must only be set with O_{CREAT,TMPFILE}. */ + { .name = "non-zero how.mode and O_RDONLY", + .how.flags = O_RDONLY, .how.mode = 0600, .err = -EINVAL }, + { .name = "non-zero how.mode and O_PATH", + .how.flags = O_PATH, .how.mode = 0600, .err = -EINVAL }, + { .name = "valid how.mode and O_CREAT", + .how.flags = O_CREAT, .how.mode = 0600 }, + { .name = "valid how.mode and O_TMPFILE", + .how.flags = O_TMPFILE | O_RDWR, .how.mode = 0600 }, + /* ->mode must only contain 0777 bits. */ + { .name = "invalid how.mode and O_CREAT", + .how.flags = O_CREAT, + .how.mode = 0xFFFF, .err = -EINVAL }, + { .name = "invalid how.mode and O_TMPFILE", + .how.flags = O_TMPFILE | O_RDWR, + .how.mode = 0x1337, .err = -EINVAL }, + + /* ->resolve must only contain RESOLVE_* flags. */ + { .name = "invalid how.resolve and O_RDONLY", + .how.flags = O_RDONLY, + .how.resolve = 0x1337, .err = -EINVAL }, + { .name = "invalid how.resolve and O_CREAT", + .how.flags = O_CREAT, + .how.resolve = 0x1337, .err = -EINVAL }, + { .name = "invalid how.resolve and O_TMPFILE", + .how.flags = O_TMPFILE | O_RDWR, + .how.resolve = 0x1337, .err = -EINVAL }, + { .name = "invalid how.resolve and O_PATH", + .how.flags = O_PATH, + .how.resolve = 0x1337, .err = -EINVAL }, + }; + + BUILD_BUG_ON(ARRAY_LEN(tests) != NUM_OPENAT2_FLAG_TESTS); + + for (int i = 0; i < ARRAY_LEN(tests); i++) { + int fd, fdflags = -1; + char *path, *fdpath = NULL; + bool failed = false; + struct flag_test *test = &tests[i]; + void (*resultfn)(const char *msg, ...) = ksft_test_result_pass; + + if (!openat2_supported) { + ksft_print_msg("openat2(2) unsupported\n"); + resultfn = ksft_test_result_skip; + goto skip; + } + + path = (test->how.flags & O_CREAT) ? "/tmp/ksft.openat2_tmpfile" : "."; + unlink(path); + + fd = sys_openat2(AT_FDCWD, path, &test->how); + if (test->err >= 0) + failed = (fd < 0); + else + failed = (fd != test->err); + if (fd >= 0) { + int otherflags; + + fdpath = fdreadlink(fd); + fdflags = fcntl(fd, F_GETFL); + otherflags = fcntl(fd, F_GETFD); + close(fd); + + E_assert(fdflags >= 0, "fcntl F_GETFL of new fd"); + E_assert(otherflags >= 0, "fcntl F_GETFD of new fd"); + + /* O_CLOEXEC isn't shown in F_GETFL. */ + if (otherflags & FD_CLOEXEC) + fdflags |= O_CLOEXEC; + /* O_CREAT is hidden from F_GETFL. */ + if (test->how.flags & O_CREAT) + fdflags |= O_CREAT; + if (!(test->how.flags & O_LARGEFILE)) + fdflags &= ~O_LARGEFILE; + failed |= (fdflags != test->how.flags); + } + + if (failed) { + resultfn = ksft_test_result_fail; + + ksft_print_msg("openat2 unexpectedly returned "); + if (fdpath) + ksft_print_msg("%d['%s'] with %X (!= %X)\n", + fd, fdpath, fdflags, + test->how.flags); + else + ksft_print_msg("%d (%s)\n", fd, strerror(-fd)); + } + +skip: + if (test->err >= 0) + resultfn("openat2 with %s succeeds\n", test->name); + else + resultfn("openat2 with %s fails with %d (%s)\n", + test->name, test->err, strerror(-test->err)); + + free(fdpath); + fflush(stdout); + } +} + +#define NUM_TESTS (NUM_OPENAT2_STRUCT_VARIATIONS * NUM_OPENAT2_STRUCT_TESTS + \ + NUM_OPENAT2_FLAG_TESTS) + +int main(int argc, char **argv) +{ + ksft_print_header(); + ksft_set_plan(NUM_TESTS); + + test_openat2_struct(); + test_openat2_flags(); + + if (ksft_get_fail_cnt() + ksft_get_error_cnt() > 0) + ksft_exit_fail(); + else + ksft_exit_pass(); +} diff --git a/tools/testing/selftests/openat2/rename_attack_test.c b/tools/testing/selftests/openat2/rename_attack_test.c new file mode 100644 index 000000000000..0a770728b436 --- /dev/null +++ b/tools/testing/selftests/openat2/rename_attack_test.c @@ -0,0 +1,160 @@ +// 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; + + struct open_how how = { + .flags = O_PATH, + .resolve = resolve, + }; + + if (!openat2_supported) { + how.resolve = 0; + ksft_print_msg("openat2(2) unsupported -- using openat(2) instead\n"); + } + + 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; + char *victim_path = "c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../../c/../.."; + + if (openat2_supported) + fd = sys_openat2(afd, victim_path, &how); + else + fd = sys_openat(afd, victim_path, &how); + + if (fd < 0) { + if (fd == -EAGAIN) + eagains++; + else if (fd == -EXDEV) + exdevs++; + else if (fd == -ENOENT) + escapes++; /* escaped outside and got ENOENT... */ + 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_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(); +} diff --git a/tools/testing/selftests/openat2/resolve_test.c b/tools/testing/selftests/openat2/resolve_test.c new file mode 100644 index 000000000000..7a94b1da8e7b --- /dev/null +++ b/tools/testing/selftests/openat2/resolve_test.c @@ -0,0 +1,523 @@ +// 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]; + + if (!openat2_supported) { + ksft_print_msg("openat2(2) unsupported\n"); + resultfn = ksft_test_result_skip; + goto skip; + } + + /* 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); + E_assert(dfd, "failed to openat root '%s': %m", test->dir); + + 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)); + } + +skip: + 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); + + /* NOTE: We should be checking for CAP_SYS_ADMIN here... */ + if (geteuid() != 0) + ksft_exit_skip("all 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(); +}