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/* SPDX-License-Identifier: GPL-2.0 */
/*
* Landlock test helpers
*
* Copyright © 2017-2020 Mickaël Salaün <mic@digikod.net>
* Copyright © 2019-2020 ANSSI
* Copyright © 2021 Microsoft Corporation
*/
#include <errno.h>
#include <linux/landlock.h>
#include <sys/capability.h>
#include <sys/socket.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include "../kselftest_harness.h"
#ifndef __maybe_unused
#define __maybe_unused __attribute__((__unused__))
#endif
/*
* TEST_F_FORK() is useful when a test drop privileges but the corresponding
* FIXTURE_TEARDOWN() requires them (e.g. to remove files from a directory
* where write actions are denied). For convenience, FIXTURE_TEARDOWN() is
* also called when the test failed, but not when FIXTURE_SETUP() failed. For
* this to be possible, we must not call abort() but instead exit smoothly
* (hence the step print).
*/
/* clang-format off */
#define TEST_F_FORK(fixture_name, test_name) \
static void fixture_name##_##test_name##_child( \
struct __test_metadata *_metadata, \
FIXTURE_DATA(fixture_name) *self, \
const FIXTURE_VARIANT(fixture_name) *variant); \
TEST_F(fixture_name, test_name) \
{ \
int status; \
const pid_t child = fork(); \
if (child < 0) \
abort(); \
if (child == 0) { \
_metadata->no_print = 1; \
fixture_name##_##test_name##_child(_metadata, self, variant); \
if (_metadata->skip) \
_exit(255); \
if (_metadata->passed) \
_exit(0); \
_exit(_metadata->step); \
} \
if (child != waitpid(child, &status, 0)) \
abort(); \
if (WIFSIGNALED(status) || !WIFEXITED(status)) { \
_metadata->passed = 0; \
_metadata->step = 1; \
return; \
} \
switch (WEXITSTATUS(status)) { \
case 0: \
_metadata->passed = 1; \
break; \
case 255: \
_metadata->passed = 1; \
_metadata->skip = 1; \
break; \
default: \
_metadata->passed = 0; \
_metadata->step = WEXITSTATUS(status); \
break; \
} \
} \
static void fixture_name##_##test_name##_child( \
struct __test_metadata __attribute__((unused)) *_metadata, \
FIXTURE_DATA(fixture_name) __attribute__((unused)) *self, \
const FIXTURE_VARIANT(fixture_name) \
__attribute__((unused)) *variant)
/* clang-format on */
#ifndef landlock_create_ruleset
static inline int
landlock_create_ruleset(const struct landlock_ruleset_attr *const attr,
const size_t size, const __u32 flags)
{
return syscall(__NR_landlock_create_ruleset, attr, size, flags);
}
#endif
#ifndef landlock_add_rule
static inline int landlock_add_rule(const int ruleset_fd,
const enum landlock_rule_type rule_type,
const void *const rule_attr,
const __u32 flags)
{
return syscall(__NR_landlock_add_rule, ruleset_fd, rule_type, rule_attr,
flags);
}
#endif
#ifndef landlock_restrict_self
static inline int landlock_restrict_self(const int ruleset_fd,
const __u32 flags)
{
return syscall(__NR_landlock_restrict_self, ruleset_fd, flags);
}
#endif
static void _init_caps(struct __test_metadata *const _metadata, bool drop_all)
{
cap_t cap_p;
/* Only these three capabilities are useful for the tests. */
const cap_value_t caps[] = {
CAP_DAC_OVERRIDE,
CAP_MKNOD,
CAP_SYS_ADMIN,
CAP_SYS_CHROOT,
};
cap_p = cap_get_proc();
EXPECT_NE(NULL, cap_p)
{
TH_LOG("Failed to cap_get_proc: %s", strerror(errno));
}
EXPECT_NE(-1, cap_clear(cap_p))
{
TH_LOG("Failed to cap_clear: %s", strerror(errno));
}
if (!drop_all) {
EXPECT_NE(-1, cap_set_flag(cap_p, CAP_PERMITTED,
ARRAY_SIZE(caps), caps, CAP_SET))
{
TH_LOG("Failed to cap_set_flag: %s", strerror(errno));
}
}
EXPECT_NE(-1, cap_set_proc(cap_p))
{
TH_LOG("Failed to cap_set_proc: %s", strerror(errno));
}
EXPECT_NE(-1, cap_free(cap_p))
{
TH_LOG("Failed to cap_free: %s", strerror(errno));
}
}
/* We cannot put such helpers in a library because of kselftest_harness.h . */
static void __maybe_unused disable_caps(struct __test_metadata *const _metadata)
{
_init_caps(_metadata, false);
}
static void __maybe_unused drop_caps(struct __test_metadata *const _metadata)
{
_init_caps(_metadata, true);
}
static void _effective_cap(struct __test_metadata *const _metadata,
const cap_value_t caps, const cap_flag_value_t value)
{
cap_t cap_p;
cap_p = cap_get_proc();
EXPECT_NE(NULL, cap_p)
{
TH_LOG("Failed to cap_get_proc: %s", strerror(errno));
}
EXPECT_NE(-1, cap_set_flag(cap_p, CAP_EFFECTIVE, 1, &caps, value))
{
TH_LOG("Failed to cap_set_flag: %s", strerror(errno));
}
EXPECT_NE(-1, cap_set_proc(cap_p))
{
TH_LOG("Failed to cap_set_proc: %s", strerror(errno));
}
EXPECT_NE(-1, cap_free(cap_p))
{
TH_LOG("Failed to cap_free: %s", strerror(errno));
}
}
static void __maybe_unused set_cap(struct __test_metadata *const _metadata,
const cap_value_t caps)
{
_effective_cap(_metadata, caps, CAP_SET);
}
static void __maybe_unused clear_cap(struct __test_metadata *const _metadata,
const cap_value_t caps)
{
_effective_cap(_metadata, caps, CAP_CLEAR);
}
/* Receives an FD from a UNIX socket. Returns the received FD, or -errno. */
static int __maybe_unused recv_fd(int usock)
{
int fd_rx;
union {
/* Aligned ancillary data buffer. */
char buf[CMSG_SPACE(sizeof(fd_rx))];
struct cmsghdr _align;
} cmsg_rx = {};
char data = '\0';
struct iovec io = {
.iov_base = &data,
.iov_len = sizeof(data),
};
struct msghdr msg = {
.msg_iov = &io,
.msg_iovlen = 1,
.msg_control = &cmsg_rx.buf,
.msg_controllen = sizeof(cmsg_rx.buf),
};
struct cmsghdr *cmsg;
int res;
res = recvmsg(usock, &msg, MSG_CMSG_CLOEXEC);
if (res < 0)
return -errno;
cmsg = CMSG_FIRSTHDR(&msg);
if (cmsg->cmsg_len != CMSG_LEN(sizeof(fd_rx)))
return -EIO;
memcpy(&fd_rx, CMSG_DATA(cmsg), sizeof(fd_rx));
return fd_rx;
}
/* Sends an FD on a UNIX socket. Returns 0 on success or -errno. */
static int __maybe_unused send_fd(int usock, int fd_tx)
{
union {
/* Aligned ancillary data buffer. */
char buf[CMSG_SPACE(sizeof(fd_tx))];
struct cmsghdr _align;
} cmsg_tx = {};
char data_tx = '.';
struct iovec io = {
.iov_base = &data_tx,
.iov_len = sizeof(data_tx),
};
struct msghdr msg = {
.msg_iov = &io,
.msg_iovlen = 1,
.msg_control = &cmsg_tx.buf,
.msg_controllen = sizeof(cmsg_tx.buf),
};
struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg);
cmsg->cmsg_len = CMSG_LEN(sizeof(fd_tx));
cmsg->cmsg_level = SOL_SOCKET;
cmsg->cmsg_type = SCM_RIGHTS;
memcpy(CMSG_DATA(cmsg), &fd_tx, sizeof(fd_tx));
if (sendmsg(usock, &msg, 0) < 0)
return -errno;
return 0;
}
static void __maybe_unused
enforce_ruleset(struct __test_metadata *const _metadata, const int ruleset_fd)
{
ASSERT_EQ(0, prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0));
ASSERT_EQ(0, landlock_restrict_self(ruleset_fd, 0))
{
TH_LOG("Failed to enforce ruleset: %s", strerror(errno));
}
}
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