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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 <linux/securebits.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() should not be used for new tests. */
#define TEST_F_FORK(fixture_name, test_name) TEST_F(fixture_name, test_name)
#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[] = {
/* clang-format off */
CAP_DAC_OVERRIDE,
CAP_MKNOD,
CAP_NET_ADMIN,
CAP_NET_BIND_SERVICE,
CAP_SYS_ADMIN,
CAP_SYS_CHROOT,
/* clang-format on */
};
const unsigned int noroot = SECBIT_NOROOT | SECBIT_NOROOT_LOCKED;
if ((cap_get_secbits() & noroot) != noroot)
EXPECT_EQ(0, cap_set_secbits(noroot));
cap_p = cap_get_proc();
EXPECT_NE(NULL, cap_p);
EXPECT_NE(-1, cap_clear(cap_p));
if (!drop_all) {
EXPECT_NE(-1, cap_set_flag(cap_p, CAP_PERMITTED,
ARRAY_SIZE(caps), caps, CAP_SET));
}
/* Automatically resets ambient capabilities. */
EXPECT_NE(-1, cap_set_proc(cap_p))
{
TH_LOG("Failed to set capabilities: %s", strerror(errno));
}
EXPECT_NE(-1, cap_free(cap_p));
/* Quickly checks that ambient capabilities are cleared. */
EXPECT_NE(-1, cap_get_ambient(caps[0]));
}
/* 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 _change_cap(struct __test_metadata *const _metadata,
const cap_flag_t flag, const cap_value_t cap,
const cap_flag_value_t value)
{
cap_t cap_p;
cap_p = cap_get_proc();
EXPECT_NE(NULL, cap_p);
EXPECT_NE(-1, cap_set_flag(cap_p, flag, 1, &cap, value));
EXPECT_NE(-1, cap_set_proc(cap_p))
{
TH_LOG("Failed to set capability %d: %s", cap, strerror(errno));
}
EXPECT_NE(-1, cap_free(cap_p));
}
static void __maybe_unused set_cap(struct __test_metadata *const _metadata,
const cap_value_t cap)
{
_change_cap(_metadata, CAP_EFFECTIVE, cap, CAP_SET);
}
static void __maybe_unused clear_cap(struct __test_metadata *const _metadata,
const cap_value_t cap)
{
_change_cap(_metadata, CAP_EFFECTIVE, cap, CAP_CLEAR);
}
static void __maybe_unused
set_ambient_cap(struct __test_metadata *const _metadata, const cap_value_t cap)
{
_change_cap(_metadata, CAP_INHERITABLE, cap, CAP_SET);
EXPECT_NE(-1, cap_set_ambient(cap, CAP_SET))
{
TH_LOG("Failed to set ambient capability %d: %s", cap,
strerror(errno));
}
}
static void __maybe_unused clear_ambient_cap(
struct __test_metadata *const _metadata, const cap_value_t cap)
{
EXPECT_EQ(1, cap_get_ambient(cap));
_change_cap(_metadata, CAP_INHERITABLE, cap, CAP_CLEAR);
EXPECT_EQ(0, cap_get_ambient(cap));
}
/* 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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