// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
 *
 * Test code for seccomp bpf.
 */

#define _GNU_SOURCE
#include <sys/types.h>

/*
 * glibc 2.26 and later have SIGSYS in siginfo_t. Before that,
 * we need to use the kernel's siginfo.h file and trick glibc
 * into accepting it.
 */
#if !__GLIBC_PREREQ(2, 26)
# include <asm/siginfo.h>
# define __have_siginfo_t 1
# define __have_sigval_t 1
# define __have_sigevent_t 1
#endif

#include <errno.h>
#include <linux/filter.h>
#include <sys/prctl.h>
#include <sys/ptrace.h>
#include <sys/user.h>
#include <linux/prctl.h>
#include <linux/ptrace.h>
#include <linux/seccomp.h>
#include <pthread.h>
#include <semaphore.h>
#include <signal.h>
#include <stddef.h>
#include <stdbool.h>
#include <string.h>
#include <time.h>
#include <limits.h>
#include <linux/elf.h>
#include <sys/uio.h>
#include <sys/utsname.h>
#include <sys/fcntl.h>
#include <sys/mman.h>
#include <sys/times.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <linux/kcmp.h>
#include <sys/resource.h>

#include <unistd.h>
#include <sys/syscall.h>
#include <poll.h>

#include "../kselftest_harness.h"
#include "../clone3/clone3_selftests.h"

/* Attempt to de-conflict with the selftests tree. */
#ifndef SKIP
#define SKIP(s, ...)    XFAIL(s, ##__VA_ARGS__)
#endif

#ifndef PR_SET_PTRACER
# define PR_SET_PTRACER 0x59616d61
#endif

#ifndef PR_SET_NO_NEW_PRIVS
#define PR_SET_NO_NEW_PRIVS 38
#define PR_GET_NO_NEW_PRIVS 39
#endif

#ifndef PR_SECCOMP_EXT
#define PR_SECCOMP_EXT 43
#endif

#ifndef SECCOMP_EXT_ACT
#define SECCOMP_EXT_ACT 1
#endif

#ifndef SECCOMP_EXT_ACT_TSYNC
#define SECCOMP_EXT_ACT_TSYNC 1
#endif

#ifndef SECCOMP_MODE_STRICT
#define SECCOMP_MODE_STRICT 1
#endif

#ifndef SECCOMP_MODE_FILTER
#define SECCOMP_MODE_FILTER 2
#endif

#ifndef SECCOMP_RET_ALLOW
struct seccomp_data {
        int nr;
        __u32 arch;
        __u64 instruction_pointer;
        __u64 args[6];
};
#endif

#ifndef SECCOMP_RET_KILL_PROCESS
#define SECCOMP_RET_KILL_PROCESS 0x80000000U /* kill the process */
#define SECCOMP_RET_KILL_THREAD  0x00000000U /* kill the thread */
#endif
#ifndef SECCOMP_RET_KILL
#define SECCOMP_RET_KILL         SECCOMP_RET_KILL_THREAD
#define SECCOMP_RET_TRAP         0x00030000U /* disallow and force a SIGSYS */
#define SECCOMP_RET_ERRNO        0x00050000U /* returns an errno */
#define SECCOMP_RET_TRACE        0x7ff00000U /* pass to a tracer or disallow */
#define SECCOMP_RET_ALLOW        0x7fff0000U /* allow */
#endif
#ifndef SECCOMP_RET_LOG
#define SECCOMP_RET_LOG          0x7ffc0000U /* allow after logging */
#endif

#ifndef __NR_seccomp
# if defined(__i386__)
#  define __NR_seccomp 354
# elif defined(__x86_64__)
#  define __NR_seccomp 317
# elif defined(__arm__)
#  define __NR_seccomp 383
# elif defined(__aarch64__)
#  define __NR_seccomp 277
# elif defined(__riscv)
#  define __NR_seccomp 277
# elif defined(__csky__)
#  define __NR_seccomp 277
# elif defined(__hppa__)
#  define __NR_seccomp 338
# elif defined(__powerpc__)
#  define __NR_seccomp 358
# elif defined(__s390__)
#  define __NR_seccomp 348
# elif defined(__xtensa__)
#  define __NR_seccomp 337
# elif defined(__sh__)
#  define __NR_seccomp 372
# else
#  warning "seccomp syscall number unknown for this architecture"
#  define __NR_seccomp 0xffff
# endif
#endif

#ifndef SECCOMP_SET_MODE_STRICT
#define SECCOMP_SET_MODE_STRICT 0
#endif

#ifndef SECCOMP_SET_MODE_FILTER
#define SECCOMP_SET_MODE_FILTER 1
#endif

#ifndef SECCOMP_GET_ACTION_AVAIL
#define SECCOMP_GET_ACTION_AVAIL 2
#endif

#ifndef SECCOMP_GET_NOTIF_SIZES
#define SECCOMP_GET_NOTIF_SIZES 3
#endif

#ifndef SECCOMP_FILTER_FLAG_TSYNC
#define SECCOMP_FILTER_FLAG_TSYNC (1UL << 0)
#endif

#ifndef SECCOMP_FILTER_FLAG_LOG
#define SECCOMP_FILTER_FLAG_LOG (1UL << 1)
#endif

#ifndef SECCOMP_FILTER_FLAG_SPEC_ALLOW
#define SECCOMP_FILTER_FLAG_SPEC_ALLOW (1UL << 2)
#endif

#ifndef PTRACE_SECCOMP_GET_METADATA
#define PTRACE_SECCOMP_GET_METADATA     0x420d

struct seccomp_metadata {
        __u64 filter_off;       /* Input: which filter */
        __u64 flags;             /* Output: filter's flags */
};
#endif

#ifndef SECCOMP_FILTER_FLAG_NEW_LISTENER
#define SECCOMP_FILTER_FLAG_NEW_LISTENER        (1UL << 3)
#endif

#ifndef SECCOMP_RET_USER_NOTIF
#define SECCOMP_RET_USER_NOTIF 0x7fc00000U

#define SECCOMP_IOC_MAGIC               '!'
#define SECCOMP_IO(nr)                  _IO(SECCOMP_IOC_MAGIC, nr)
#define SECCOMP_IOR(nr, type)           _IOR(SECCOMP_IOC_MAGIC, nr, type)
#define SECCOMP_IOW(nr, type)           _IOW(SECCOMP_IOC_MAGIC, nr, type)
#define SECCOMP_IOWR(nr, type)          _IOWR(SECCOMP_IOC_MAGIC, nr, type)

/* Flags for seccomp notification fd ioctl. */
#define SECCOMP_IOCTL_NOTIF_RECV        SECCOMP_IOWR(0, struct seccomp_notif)
#define SECCOMP_IOCTL_NOTIF_SEND        SECCOMP_IOWR(1, \
                                                struct seccomp_notif_resp)
#define SECCOMP_IOCTL_NOTIF_ID_VALID    SECCOMP_IOW(2, __u64)

struct seccomp_notif {
        __u64 id;
        __u32 pid;
        __u32 flags;
        struct seccomp_data data;
};

struct seccomp_notif_resp {
        __u64 id;
        __s64 val;
        __s32 error;
        __u32 flags;
};

struct seccomp_notif_sizes {
        __u16 seccomp_notif;
        __u16 seccomp_notif_resp;
        __u16 seccomp_data;
};
#endif

#ifndef SECCOMP_IOCTL_NOTIF_ADDFD
/* On success, the return value is the remote process's added fd number */
#define SECCOMP_IOCTL_NOTIF_ADDFD       SECCOMP_IOW(3,  \
                                                struct seccomp_notif_addfd)

/* valid flags for seccomp_notif_addfd */
#define SECCOMP_ADDFD_FLAG_SETFD        (1UL << 0) /* Specify remote fd */

struct seccomp_notif_addfd {
        __u64 id;
        __u32 flags;
        __u32 srcfd;
        __u32 newfd;
        __u32 newfd_flags;
};
#endif

#ifndef SECCOMP_ADDFD_FLAG_SEND
#define SECCOMP_ADDFD_FLAG_SEND (1UL << 1) /* Addfd and return it, atomically */
#endif

struct seccomp_notif_addfd_small {
        __u64 id;
        char weird[4];
};
#define SECCOMP_IOCTL_NOTIF_ADDFD_SMALL \
        SECCOMP_IOW(3, struct seccomp_notif_addfd_small)

struct seccomp_notif_addfd_big {
        union {
                struct seccomp_notif_addfd addfd;
                char buf[sizeof(struct seccomp_notif_addfd) + 8];
        };
};
#define SECCOMP_IOCTL_NOTIF_ADDFD_BIG   \
        SECCOMP_IOWR(3, struct seccomp_notif_addfd_big)

#ifndef PTRACE_EVENTMSG_SYSCALL_ENTRY
#define PTRACE_EVENTMSG_SYSCALL_ENTRY   1
#define PTRACE_EVENTMSG_SYSCALL_EXIT    2
#endif

#ifndef SECCOMP_USER_NOTIF_FLAG_CONTINUE
#define SECCOMP_USER_NOTIF_FLAG_CONTINUE 0x00000001
#endif

#ifndef SECCOMP_FILTER_FLAG_TSYNC_ESRCH
#define SECCOMP_FILTER_FLAG_TSYNC_ESRCH (1UL << 4)
#endif

#ifndef seccomp
int seccomp(unsigned int op, unsigned int flags, void *args)
{
        errno = 0;
        return syscall(__NR_seccomp, op, flags, args);
}
#endif

#if __BYTE_ORDER == __LITTLE_ENDIAN
#define syscall_arg(_n) (offsetof(struct seccomp_data, args[_n]))
#elif __BYTE_ORDER == __BIG_ENDIAN
#define syscall_arg(_n) (offsetof(struct seccomp_data, args[_n]) + sizeof(__u32))
#else
#error "wut? Unknown __BYTE_ORDER?!"
#endif

#define SIBLING_EXIT_UNKILLED   0xbadbeef
#define SIBLING_EXIT_FAILURE    0xbadface
#define SIBLING_EXIT_NEWPRIVS   0xbadfeed

static int __filecmp(pid_t pid1, pid_t pid2, int fd1, int fd2)
{
#ifdef __NR_kcmp
        errno = 0;
        return syscall(__NR_kcmp, pid1, pid2, KCMP_FILE, fd1, fd2);
#else
        errno = ENOSYS;
        return -1;
#endif
}

/* Have TH_LOG report actual location filecmp() is used. */
#define filecmp(pid1, pid2, fd1, fd2)   ({              \
        int _ret;                                       \
                                                        \
        _ret = __filecmp(pid1, pid2, fd1, fd2);         \
        if (_ret != 0) {                                \
                if (_ret < 0 && errno == ENOSYS) {      \
                        TH_LOG("kcmp() syscall missing (test is less accurate)");\
                        _ret = 0;                       \
                }                                       \
        }                                               \
        _ret; })

TEST(kcmp)
{
        int ret;

        ret = __filecmp(getpid(), getpid(), 1, 1);
        EXPECT_EQ(ret, 0);
        if (ret != 0 && errno == ENOSYS)
                SKIP(return, "Kernel does not support kcmp() (missing CONFIG_KCMP?)");
}

TEST(mode_strict_support)
{
        long ret;

        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_STRICT, NULL, NULL, NULL);
        ASSERT_EQ(0, ret) {
                TH_LOG("Kernel does not support CONFIG_SECCOMP");
        }
        syscall(__NR_exit, 0);
}

TEST_SIGNAL(mode_strict_cannot_call_prctl, SIGKILL)
{
        long ret;

        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_STRICT, NULL, NULL, NULL);
        ASSERT_EQ(0, ret) {
                TH_LOG("Kernel does not support CONFIG_SECCOMP");
        }
        syscall(__NR_prctl, PR_SET_SECCOMP, SECCOMP_MODE_FILTER,
                NULL, NULL, NULL);
        EXPECT_FALSE(true) {
                TH_LOG("Unreachable!");
        }
}

/* Note! This doesn't test no new privs behavior */
TEST(no_new_privs_support)
{
        long ret;

        ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
        EXPECT_EQ(0, ret) {
                TH_LOG("Kernel does not support PR_SET_NO_NEW_PRIVS!");
        }
}

/* Tests kernel support by checking for a copy_from_user() fault on NULL. */
TEST(mode_filter_support)
{
        long ret;

        ret = prctl(PR_SET_NO_NEW_PRIVS, 1, NULL, 0, 0);
        ASSERT_EQ(0, ret) {
                TH_LOG("Kernel does not support PR_SET_NO_NEW_PRIVS!");
        }
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, NULL, NULL, NULL);
        EXPECT_EQ(-1, ret);
        EXPECT_EQ(EFAULT, errno) {
                TH_LOG("Kernel does not support CONFIG_SECCOMP_FILTER!");
        }
}

TEST(mode_filter_without_nnp)
{
        struct sock_filter filter[] = {
                BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),
        };
        struct sock_fprog prog = {
                .len = (unsigned short)ARRAY_SIZE(filter),
                .filter = filter,
        };
        long ret;

        ret = prctl(PR_GET_NO_NEW_PRIVS, 0, NULL, 0, 0);
        ASSERT_LE(0, ret) {
                TH_LOG("Expected 0 or unsupported for NO_NEW_PRIVS");
        }
        errno = 0;
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog, 0, 0);
        /* Succeeds with CAP_SYS_ADMIN, fails without */
        /* TODO(wad) check caps not euid */
        if (geteuid()) {
                EXPECT_EQ(-1, ret);
                EXPECT_EQ(EACCES, errno);
        } else {
                EXPECT_EQ(0, ret);
        }
}

#define MAX_INSNS_PER_PATH 32768

TEST(filter_size_limits)
{
        int i;
        int count = BPF_MAXINSNS + 1;
        struct sock_filter allow[] = {
                BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),
        };
        struct sock_filter *filter;
        struct sock_fprog prog = { };
        long ret;

        filter = calloc(count, sizeof(*filter));
        ASSERT_NE(NULL, filter);

        for (i = 0; i < count; i++)
                filter[i] = allow[0];

        ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
        ASSERT_EQ(0, ret);

        prog.filter = filter;
        prog.len = count;

        /* Too many filter instructions in a single filter. */
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog, 0, 0);
        ASSERT_NE(0, ret) {
                TH_LOG("Installing %d insn filter was allowed", prog.len);
        }

        /* One less is okay, though. */
        prog.len -= 1;
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog, 0, 0);
        ASSERT_EQ(0, ret) {
                TH_LOG("Installing %d insn filter wasn't allowed", prog.len);
        }
}

TEST(filter_chain_limits)
{
        int i;
        int count = BPF_MAXINSNS;
        struct sock_filter allow[] = {
                BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),
        };
        struct sock_filter *filter;
        struct sock_fprog prog = { };
        long ret;

        filter = calloc(count, sizeof(*filter));
        ASSERT_NE(NULL, filter);

        for (i = 0; i < count; i++)
                filter[i] = allow[0];

        ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
        ASSERT_EQ(0, ret);

        prog.filter = filter;
        prog.len = 1;

        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog, 0, 0);
        ASSERT_EQ(0, ret);

        prog.len = count;

        /* Too many total filter instructions. */
        for (i = 0; i < MAX_INSNS_PER_PATH; i++) {
                ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog, 0, 0);
                if (ret != 0)
                        break;
        }
        ASSERT_NE(0, ret) {
                TH_LOG("Allowed %d %d-insn filters (total with penalties:%d)",
                       i, count, i * (count + 4));
        }
}

TEST(mode_filter_cannot_move_to_strict)
{
        struct sock_filter filter[] = {
                BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),
        };
        struct sock_fprog prog = {
                .len = (unsigned short)ARRAY_SIZE(filter),
                .filter = filter,
        };
        long ret;

        ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
        ASSERT_EQ(0, ret);

        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog, 0, 0);
        ASSERT_EQ(0, ret);

        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_STRICT, NULL, 0, 0);
        EXPECT_EQ(-1, ret);
        EXPECT_EQ(EINVAL, errno);
}


TEST(mode_filter_get_seccomp)
{
        struct sock_filter filter[] = {
                BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),
        };
        struct sock_fprog prog = {
                .len = (unsigned short)ARRAY_SIZE(filter),
                .filter = filter,
        };
        long ret;

        ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
        ASSERT_EQ(0, ret);

        ret = prctl(PR_GET_SECCOMP, 0, 0, 0, 0);
        EXPECT_EQ(0, ret);

        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog, 0, 0);
        ASSERT_EQ(0, ret);

        ret = prctl(PR_GET_SECCOMP, 0, 0, 0, 0);
        EXPECT_EQ(2, ret);
}


TEST(ALLOW_all)
{
        struct sock_filter filter[] = {
                BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),
        };
        struct sock_fprog prog = {
                .len = (unsigned short)ARRAY_SIZE(filter),
                .filter = filter,
        };
        long ret;

        ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
        ASSERT_EQ(0, ret);

        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog);
        ASSERT_EQ(0, ret);
}

TEST(empty_prog)
{
        struct sock_filter filter[] = {
        };
        struct sock_fprog prog = {
                .len = (unsigned short)ARRAY_SIZE(filter),
                .filter = filter,
        };
        long ret;

        ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
        ASSERT_EQ(0, ret);

        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog);
        EXPECT_EQ(-1, ret);
        EXPECT_EQ(EINVAL, errno);
}

TEST(log_all)
{
        struct sock_filter filter[] = {
                BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_LOG),
        };
        struct sock_fprog prog = {
                .len = (unsigned short)ARRAY_SIZE(filter),
                .filter = filter,
        };
        long ret;
        pid_t parent = getppid();

        ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
        ASSERT_EQ(0, ret);

        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog);
        ASSERT_EQ(0, ret);

        /* getppid() should succeed and be logged (no check for logging) */
        EXPECT_EQ(parent, syscall(__NR_getppid));
}

TEST_SIGNAL(unknown_ret_is_kill_inside, SIGSYS)
{
        struct sock_filter filter[] = {
                BPF_STMT(BPF_RET|BPF_K, 0x10000000U),
        };
        struct sock_fprog prog = {
                .len = (unsigned short)ARRAY_SIZE(filter),
                .filter = filter,
        };
        long ret;

        ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
        ASSERT_EQ(0, ret);

        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog);
        ASSERT_EQ(0, ret);
        EXPECT_EQ(0, syscall(__NR_getpid)) {
                TH_LOG("getpid() shouldn't ever return");
        }
}

/* return code >= 0x80000000 is unused. */
TEST_SIGNAL(unknown_ret_is_kill_above_allow, SIGSYS)
{
        struct sock_filter filter[] = {
                BPF_STMT(BPF_RET|BPF_K, 0x90000000U),
        };
        struct sock_fprog prog = {
                .len = (unsigned short)ARRAY_SIZE(filter),
                .filter = filter,
        };
        long ret;

        ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
        ASSERT_EQ(0, ret);

        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog);
        ASSERT_EQ(0, ret);
        EXPECT_EQ(0, syscall(__NR_getpid)) {
                TH_LOG("getpid() shouldn't ever return");
        }
}

TEST_SIGNAL(KILL_all, SIGSYS)
{
        struct sock_filter filter[] = {
                BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_KILL),
        };
        struct sock_fprog prog = {
                .len = (unsigned short)ARRAY_SIZE(filter),
                .filter = filter,
        };
        long ret;

        ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
        ASSERT_EQ(0, ret);

        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog);
        ASSERT_EQ(0, ret);
}

TEST_SIGNAL(KILL_one, SIGSYS)
{
        struct sock_filter filter[] = {
                BPF_STMT(BPF_LD|BPF_W|BPF_ABS,
                        offsetof(struct seccomp_data, nr)),
                BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, __NR_getpid, 0, 1),
                BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_KILL),
                BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),
        };
        struct sock_fprog prog = {
                .len = (unsigned short)ARRAY_SIZE(filter),
                .filter = filter,
        };
        long ret;
        pid_t parent = getppid();

        ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
        ASSERT_EQ(0, ret);

        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog);
        ASSERT_EQ(0, ret);

        EXPECT_EQ(parent, syscall(__NR_getppid));
        /* getpid() should never return. */
        EXPECT_EQ(0, syscall(__NR_getpid));
}

TEST_SIGNAL(KILL_one_arg_one, SIGSYS)
{
        void *fatal_address;
        struct sock_filter filter[] = {
                BPF_STMT(BPF_LD|BPF_W|BPF_ABS,
                        offsetof(struct seccomp_data, nr)),
                BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, __NR_times, 1, 0),
                BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),
                /* Only both with lower 32-bit for now. */
                BPF_STMT(BPF_LD|BPF_W|BPF_ABS, syscall_arg(0)),
                BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K,
                        (unsigned long)&fatal_address, 0, 1),
                BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_KILL),
                BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),
        };
        struct sock_fprog prog = {
                .len = (unsigned short)ARRAY_SIZE(filter),
                .filter = filter,
        };
        long ret;
        pid_t parent = getppid();
        struct tms timebuf;
        clock_t clock = times(&timebuf);

        ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
        ASSERT_EQ(0, ret);

        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog);
        ASSERT_EQ(0, ret);

        EXPECT_EQ(parent, syscall(__NR_getppid));
        EXPECT_LE(clock, syscall(__NR_times, &timebuf));
        /* times() should never return. */
        EXPECT_EQ(0, syscall(__NR_times, &fatal_address));
}

TEST_SIGNAL(KILL_one_arg_six, SIGSYS)
{
#ifndef __NR_mmap2
        int sysno = __NR_mmap;
#else
        int sysno = __NR_mmap2;
#endif
        struct sock_filter filter[] = {
                BPF_STMT(BPF_LD|BPF_W|BPF_ABS,
                        offsetof(struct seccomp_data, nr)),
                BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, sysno, 1, 0),
                BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),
                /* Only both with lower 32-bit for now. */
                BPF_STMT(BPF_LD|BPF_W|BPF_ABS, syscall_arg(5)),
                BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, 0x0C0FFEE, 0, 1),
                BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_KILL),
                BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),
        };
        struct sock_fprog prog = {
                .len = (unsigned short)ARRAY_SIZE(filter),
                .filter = filter,
        };
        long ret;
        pid_t parent = getppid();
        int fd;
        void *map1, *map2;
        int page_size = sysconf(_SC_PAGESIZE);

        ASSERT_LT(0, page_size);

        ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
        ASSERT_EQ(0, ret);

        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog);
        ASSERT_EQ(0, ret);

        fd = open("/dev/zero", O_RDONLY);
        ASSERT_NE(-1, fd);

        EXPECT_EQ(parent, syscall(__NR_getppid));
        map1 = (void *)syscall(sysno,
                NULL, page_size, PROT_READ, MAP_PRIVATE, fd, page_size);
        EXPECT_NE(MAP_FAILED, map1);
        /* mmap2() should never return. */
        map2 = (void *)syscall(sysno,
                 NULL, page_size, PROT_READ, MAP_PRIVATE, fd, 0x0C0FFEE);
        EXPECT_EQ(MAP_FAILED, map2);

        /* The test failed, so clean up the resources. */
        munmap(map1, page_size);
        munmap(map2, page_size);
        close(fd);
}

/* This is a thread task to die via seccomp filter violation. */
void *kill_thread(void *data)
{
        bool die = (bool)data;

        if (die) {
                prctl(PR_GET_SECCOMP, 0, 0, 0, 0);
                return (void *)SIBLING_EXIT_FAILURE;
        }

        return (void *)SIBLING_EXIT_UNKILLED;
}

enum kill_t {
        KILL_THREAD,
        KILL_PROCESS,
        RET_UNKNOWN
};

/* Prepare a thread that will kill itself or both of us. */
void kill_thread_or_group(struct __test_metadata *_metadata,
                          enum kill_t kill_how)
{
        pthread_t thread;
        void *status;
        /* Kill only when calling __NR_prctl. */
        struct sock_filter filter_thread[] = {
                BPF_STMT(BPF_LD|BPF_W|BPF_ABS,
                        offsetof(struct seccomp_data, nr)),
                BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, __NR_prctl, 0, 1),
                BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_KILL_THREAD),
                BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),
        };
        struct sock_fprog prog_thread = {
                .len = (unsigned short)ARRAY_SIZE(filter_thread),
                .filter = filter_thread,
        };
        int kill = kill_how == KILL_PROCESS ? SECCOMP_RET_KILL_PROCESS : 0xAAAAAAAAA;
        struct sock_filter filter_process[] = {
                BPF_STMT(BPF_LD|BPF_W|BPF_ABS,
                        offsetof(struct seccomp_data, nr)),
                BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, __NR_prctl, 0, 1),
                BPF_STMT(BPF_RET|BPF_K, kill),
                BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),
        };
        struct sock_fprog prog_process = {
                .len = (unsigned short)ARRAY_SIZE(filter_process),
                .filter = filter_process,
        };

        ASSERT_EQ(0, prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0)) {
                TH_LOG("Kernel does not support PR_SET_NO_NEW_PRIVS!");
        }

        ASSERT_EQ(0, seccomp(SECCOMP_SET_MODE_FILTER, 0,
                             kill_how == KILL_THREAD ? &prog_thread
                                                     : &prog_process));

        /*
         * Add the KILL_THREAD rule again to make sure that the KILL_PROCESS
         * flag cannot be downgraded by a new filter.
         */
        if (kill_how == KILL_PROCESS)
                ASSERT_EQ(0, seccomp(SECCOMP_SET_MODE_FILTER, 0, &prog_thread));

        /* Start a thread that will exit immediately. */
        ASSERT_EQ(0, pthread_create(&thread, NULL, kill_thread, (void *)false));
        ASSERT_EQ(0, pthread_join(thread, &status));
        ASSERT_EQ(SIBLING_EXIT_UNKILLED, (unsigned long)status);

        /* Start a thread that will die immediately. */
        ASSERT_EQ(0, pthread_create(&thread, NULL, kill_thread, (void *)true));
        ASSERT_EQ(0, pthread_join(thread, &status));
        ASSERT_NE(SIBLING_EXIT_FAILURE, (unsigned long)status);

        /*
         * If we get here, only the spawned thread died. Let the parent know
         * the whole process didn't die (i.e. this thread, the spawner,
         * stayed running).
         */
        exit(42);
}

TEST(KILL_thread)
{
        int status;
        pid_t child_pid;

        child_pid = fork();
        ASSERT_LE(0, child_pid);
        if (child_pid == 0) {
                kill_thread_or_group(_metadata, KILL_THREAD);
                _exit(38);
        }

        ASSERT_EQ(child_pid, waitpid(child_pid, &status, 0));

        /* If only the thread was killed, we'll see exit 42. */
        ASSERT_TRUE(WIFEXITED(status));
        ASSERT_EQ(42, WEXITSTATUS(status));
}

TEST(KILL_process)
{
        int status;
        pid_t child_pid;

        child_pid = fork();
        ASSERT_LE(0, child_pid);
        if (child_pid == 0) {
                kill_thread_or_group(_metadata, KILL_PROCESS);
                _exit(38);
        }

        ASSERT_EQ(child_pid, waitpid(child_pid, &status, 0));

        /* If the entire process was killed, we'll see SIGSYS. */
        ASSERT_TRUE(WIFSIGNALED(status));
        ASSERT_EQ(SIGSYS, WTERMSIG(status));
}

TEST(KILL_unknown)
{
        int status;
        pid_t child_pid;

        child_pid = fork();
        ASSERT_LE(0, child_pid);
        if (child_pid == 0) {
                kill_thread_or_group(_metadata, RET_UNKNOWN);
                _exit(38);
        }

        ASSERT_EQ(child_pid, waitpid(child_pid, &status, 0));

        /* If the entire process was killed, we'll see SIGSYS. */
        EXPECT_TRUE(WIFSIGNALED(status)) {
                TH_LOG("Unknown SECCOMP_RET is only killing the thread?");
        }
        ASSERT_EQ(SIGSYS, WTERMSIG(status));
}

/* TODO(wad) add 64-bit versus 32-bit arg tests. */
TEST(arg_out_of_range)
{
        struct sock_filter filter[] = {
                BPF_STMT(BPF_LD|BPF_W|BPF_ABS, syscall_arg(6)),
                BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),
        };
        struct sock_fprog prog = {
                .len = (unsigned short)ARRAY_SIZE(filter),
                .filter = filter,
        };
        long ret;

        ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
        ASSERT_EQ(0, ret);

        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog);
        EXPECT_EQ(-1, ret);
        EXPECT_EQ(EINVAL, errno);
}

#define ERRNO_FILTER(name, errno)                                       \
        struct sock_filter _read_filter_##name[] = {                    \
                BPF_STMT(BPF_LD|BPF_W|BPF_ABS,                          \
                        offsetof(struct seccomp_data, nr)),             \
                BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, __NR_read, 0, 1),       \
                BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ERRNO | errno),     \
                BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),             \
        };                                                              \
        struct sock_fprog prog_##name = {                               \
                .len = (unsigned short)ARRAY_SIZE(_read_filter_##name), \
                .filter = _read_filter_##name,                          \
        }

/* Make sure basic errno values are correctly passed through a filter. */
TEST(ERRNO_valid)
{
        ERRNO_FILTER(valid, E2BIG);
        long ret;
        pid_t parent = getppid();

        ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
        ASSERT_EQ(0, ret);

        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog_valid);
        ASSERT_EQ(0, ret);

        EXPECT_EQ(parent, syscall(__NR_getppid));
        EXPECT_EQ(-1, read(0, NULL, 0));
        EXPECT_EQ(E2BIG, errno);
}

/* Make sure an errno of zero is correctly handled by the arch code. */
TEST(ERRNO_zero)
{
        ERRNO_FILTER(zero, 0);
        long ret;
        pid_t parent = getppid();

        ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
        ASSERT_EQ(0, ret);

        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog_zero);
        ASSERT_EQ(0, ret);

        EXPECT_EQ(parent, syscall(__NR_getppid));
        /* "errno" of 0 is ok. */
        EXPECT_EQ(0, read(0, NULL, 0));
}

/*
 * The SECCOMP_RET_DATA mask is 16 bits wide, but errno is smaller.
 * This tests that the errno value gets capped correctly, fixed by
 * 580c57f10768 ("seccomp: cap SECCOMP_RET_ERRNO data to MAX_ERRNO").
 */
TEST(ERRNO_capped)
{
        ERRNO_FILTER(capped, 4096);
        long ret;
        pid_t parent = getppid();

        ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
        ASSERT_EQ(0, ret);

        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog_capped);
        ASSERT_EQ(0, ret);

        EXPECT_EQ(parent, syscall(__NR_getppid));
        EXPECT_EQ(-1, read(0, NULL, 0));
        EXPECT_EQ(4095, errno);
}

/*
 * Filters are processed in reverse order: last applied is executed first.
 * Since only the SECCOMP_RET_ACTION mask is tested for return values, the
 * SECCOMP_RET_DATA mask results will follow the most recently applied
 * matching filter return (and not the lowest or highest value).
 */
TEST(ERRNO_order)
{
        ERRNO_FILTER(first,  11);
        ERRNO_FILTER(second, 13);
        ERRNO_FILTER(third,  12);
        long ret;
        pid_t parent = getppid();

        ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
        ASSERT_EQ(0, ret);

        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog_first);
        ASSERT_EQ(0, ret);

        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog_second);
        ASSERT_EQ(0, ret);

        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog_third);
        ASSERT_EQ(0, ret);

        EXPECT_EQ(parent, syscall(__NR_getppid));
        EXPECT_EQ(-1, read(0, NULL, 0));
        EXPECT_EQ(12, errno);
}

FIXTURE(TRAP) {
        struct sock_fprog prog;
};

FIXTURE_SETUP(TRAP)
{
        struct sock_filter filter[] = {
                BPF_STMT(BPF_LD|BPF_W|BPF_ABS,
                        offsetof(struct seccomp_data, nr)),
                BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, __NR_getpid, 0, 1),
                BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_TRAP),
                BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),
        };

        memset(&self->prog, 0, sizeof(self->prog));
        self->prog.filter = malloc(sizeof(filter));
        ASSERT_NE(NULL, self->prog.filter);
        memcpy(self->prog.filter, filter, sizeof(filter));
        self->prog.len = (unsigned short)ARRAY_SIZE(filter);
}

FIXTURE_TEARDOWN(TRAP)
{
        if (self->prog.filter)
                free(self->prog.filter);
}

TEST_F_SIGNAL(TRAP, dfl, SIGSYS)
{
        long ret;

        ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
        ASSERT_EQ(0, ret);

        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->prog);
        ASSERT_EQ(0, ret);
        syscall(__NR_getpid);
}

/* Ensure that SIGSYS overrides SIG_IGN */
TEST_F_SIGNAL(TRAP, ign, SIGSYS)
{
        long ret;

        ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
        ASSERT_EQ(0, ret);

        signal(SIGSYS, SIG_IGN);

        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->prog);
        ASSERT_EQ(0, ret);
        syscall(__NR_getpid);
}

static siginfo_t TRAP_info;
static volatile int TRAP_nr;
static void TRAP_action(int nr, siginfo_t *info, void *void_context)
{
        memcpy(&TRAP_info, info, sizeof(TRAP_info));
        TRAP_nr = nr;
}

TEST_F(TRAP, handler)
{
        int ret, test;
        struct sigaction act;
        sigset_t mask;

        memset(&act, 0, sizeof(act));
        sigemptyset(&mask);
        sigaddset(&mask, SIGSYS);

        act.sa_sigaction = &TRAP_action;
        act.sa_flags = SA_SIGINFO;
        ret = sigaction(SIGSYS, &act, NULL);
        ASSERT_EQ(0, ret) {
                TH_LOG("sigaction failed");
        }
        ret = sigprocmask(SIG_UNBLOCK, &mask, NULL);
        ASSERT_EQ(0, ret) {
                TH_LOG("sigprocmask failed");
        }

        ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
        ASSERT_EQ(0, ret);
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->prog);
        ASSERT_EQ(0, ret);
        TRAP_nr = 0;
        memset(&TRAP_info, 0, sizeof(TRAP_info));
        /* Expect the registers to be rolled back. (nr = error) may vary
         * based on arch. */
        ret = syscall(__NR_getpid);
        /* Silence gcc warning about volatile. */
        test = TRAP_nr;
        EXPECT_EQ(SIGSYS, test);
        struct local_sigsys {
                void *_call_addr;       /* calling user insn */
                int _syscall;           /* triggering system call number */
                unsigned int _arch;     /* AUDIT_ARCH_* of syscall */
        } *sigsys = (struct local_sigsys *)
#ifdef si_syscall
                &(TRAP_info.si_call_addr);
#else
                &TRAP_info.si_pid;
#endif
        EXPECT_EQ(__NR_getpid, sigsys->_syscall);
        /* Make sure arch is non-zero. */
        EXPECT_NE(0, sigsys->_arch);
        EXPECT_NE(0, (unsigned long)sigsys->_call_addr);
}

FIXTURE(precedence) {
        struct sock_fprog allow;
        struct sock_fprog log;
        struct sock_fprog trace;
        struct sock_fprog error;
        struct sock_fprog trap;
        struct sock_fprog kill;
};

FIXTURE_SETUP(precedence)
{
        struct sock_filter allow_insns[] = {
                BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),
        };
        struct sock_filter log_insns[] = {
                BPF_STMT(BPF_LD|BPF_W|BPF_ABS,
                        offsetof(struct seccomp_data, nr)),
                BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, __NR_getpid, 1, 0),
                BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),
                BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_LOG),
        };
        struct sock_filter trace_insns[] = {
                BPF_STMT(BPF_LD|BPF_W|BPF_ABS,
                        offsetof(struct seccomp_data, nr)),
                BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, __NR_getpid, 1, 0),
                BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),
                BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_TRACE),
        };
        struct sock_filter error_insns[] = {
                BPF_STMT(BPF_LD|BPF_W|BPF_ABS,
                        offsetof(struct seccomp_data, nr)),
                BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, __NR_getpid, 1, 0),
                BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),
                BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ERRNO),
        };
        struct sock_filter trap_insns[] = {
                BPF_STMT(BPF_LD|BPF_W|BPF_ABS,
                        offsetof(struct seccomp_data, nr)),
                BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, __NR_getpid, 1, 0),
                BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),
                BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_TRAP),
        };
        struct sock_filter kill_insns[] = {
                BPF_STMT(BPF_LD|BPF_W|BPF_ABS,
                        offsetof(struct seccomp_data, nr)),
                BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, __NR_getpid, 1, 0),
                BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),
                BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_KILL),
        };

        memset(self, 0, sizeof(*self));
#define FILTER_ALLOC(_x) \
        self->_x.filter = malloc(sizeof(_x##_insns)); \
        ASSERT_NE(NULL, self->_x.filter); \
        memcpy(self->_x.filter, &_x##_insns, sizeof(_x##_insns)); \
        self->_x.len = (unsigned short)ARRAY_SIZE(_x##_insns)
        FILTER_ALLOC(allow);
        FILTER_ALLOC(log);
        FILTER_ALLOC(trace);
        FILTER_ALLOC(error);
        FILTER_ALLOC(trap);
        FILTER_ALLOC(kill);
}

FIXTURE_TEARDOWN(precedence)
{
#define FILTER_FREE(_x) if (self->_x.filter) free(self->_x.filter)
        FILTER_FREE(allow);
        FILTER_FREE(log);
        FILTER_FREE(trace);
        FILTER_FREE(error);
        FILTER_FREE(trap);
        FILTER_FREE(kill);
}

TEST_F(precedence, allow_ok)
{
        pid_t parent, res = 0;
        long ret;

        parent = getppid();
        ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
        ASSERT_EQ(0, ret);

        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->allow);
        ASSERT_EQ(0, ret);
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->log);
        ASSERT_EQ(0, ret);
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->trace);
        ASSERT_EQ(0, ret);
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->error);
        ASSERT_EQ(0, ret);
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->trap);
        ASSERT_EQ(0, ret);
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->kill);
        ASSERT_EQ(0, ret);
        /* Should work just fine. */
        res = syscall(__NR_getppid);
        EXPECT_EQ(parent, res);
}

TEST_F_SIGNAL(precedence, kill_is_highest, SIGSYS)
{
        pid_t parent, res = 0;
        long ret;

        parent = getppid();
        ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
        ASSERT_EQ(0, ret);

        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->allow);
        ASSERT_EQ(0, ret);
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->log);
        ASSERT_EQ(0, ret);
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->trace);
        ASSERT_EQ(0, ret);
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->error);
        ASSERT_EQ(0, ret);
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->trap);
        ASSERT_EQ(0, ret);
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->kill);
        ASSERT_EQ(0, ret);
        /* Should work just fine. */
        res = syscall(__NR_getppid);
        EXPECT_EQ(parent, res);
        /* getpid() should never return. */
        res = syscall(__NR_getpid);
        EXPECT_EQ(0, res);
}

TEST_F_SIGNAL(precedence, kill_is_highest_in_any_order, SIGSYS)
{
        pid_t parent;
        long ret;

        parent = getppid();
        ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
        ASSERT_EQ(0, ret);

        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->allow);
        ASSERT_EQ(0, ret);
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->kill);
        ASSERT_EQ(0, ret);
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->error);
        ASSERT_EQ(0, ret);
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->log);
        ASSERT_EQ(0, ret);
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->trace);
        ASSERT_EQ(0, ret);
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->trap);
        ASSERT_EQ(0, ret);
        /* Should work just fine. */
        EXPECT_EQ(parent, syscall(__NR_getppid));
        /* getpid() should never return. */
        EXPECT_EQ(0, syscall(__NR_getpid));
}

TEST_F_SIGNAL(precedence, trap_is_second, SIGSYS)
{
        pid_t parent;
        long ret;

        parent = getppid();
        ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
        ASSERT_EQ(0, ret);

        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->allow);
        ASSERT_EQ(0, ret);
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->log);
        ASSERT_EQ(0, ret);
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->trace);
        ASSERT_EQ(0, ret);
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->error);
        ASSERT_EQ(0, ret);
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->trap);
        ASSERT_EQ(0, ret);
        /* Should work just fine. */
        EXPECT_EQ(parent, syscall(__NR_getppid));
        /* getpid() should never return. */
        EXPECT_EQ(0, syscall(__NR_getpid));
}

TEST_F_SIGNAL(precedence, trap_is_second_in_any_order, SIGSYS)
{
        pid_t parent;
        long ret;

        parent = getppid();
        ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
        ASSERT_EQ(0, ret);

        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->allow);
        ASSERT_EQ(0, ret);
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->trap);
        ASSERT_EQ(0, ret);
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->log);
        ASSERT_EQ(0, ret);
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->trace);
        ASSERT_EQ(0, ret);
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->error);
        ASSERT_EQ(0, ret);
        /* Should work just fine. */
        EXPECT_EQ(parent, syscall(__NR_getppid));
        /* getpid() should never return. */
        EXPECT_EQ(0, syscall(__NR_getpid));
}

TEST_F(precedence, errno_is_third)
{
        pid_t parent;
        long ret;

        parent = getppid();
        ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
        ASSERT_EQ(0, ret);

        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->allow);
        ASSERT_EQ(0, ret);
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->log);
        ASSERT_EQ(0, ret);
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->trace);
        ASSERT_EQ(0, ret);
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->error);
        ASSERT_EQ(0, ret);
        /* Should work just fine. */
        EXPECT_EQ(parent, syscall(__NR_getppid));
        EXPECT_EQ(0, syscall(__NR_getpid));
}

TEST_F(precedence, errno_is_third_in_any_order)
{
        pid_t parent;
        long ret;

        parent = getppid();
        ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
        ASSERT_EQ(0, ret);

        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->log);
        ASSERT_EQ(0, ret);
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->error);
        ASSERT_EQ(0, ret);
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->trace);
        ASSERT_EQ(0, ret);
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->allow);
        ASSERT_EQ(0, ret);
        /* Should work just fine. */
        EXPECT_EQ(parent, syscall(__NR_getppid));
        EXPECT_EQ(0, syscall(__NR_getpid));
}

TEST_F(precedence, trace_is_fourth)
{
        pid_t parent;
        long ret;

        parent = getppid();
        ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
        ASSERT_EQ(0, ret);

        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->allow);
        ASSERT_EQ(0, ret);
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->log);
        ASSERT_EQ(0, ret);
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->trace);
        ASSERT_EQ(0, ret);
        /* Should work just fine. */
        EXPECT_EQ(parent, syscall(__NR_getppid));
        /* No ptracer */
        EXPECT_EQ(-1, syscall(__NR_getpid));
}

TEST_F(precedence, trace_is_fourth_in_any_order)
{
        pid_t parent;
        long ret;

        parent = getppid();
        ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
        ASSERT_EQ(0, ret);

        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->trace);
        ASSERT_EQ(0, ret);
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->allow);
        ASSERT_EQ(0, ret);
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->log);
        ASSERT_EQ(0, ret);
        /* Should work just fine. */
        EXPECT_EQ(parent, syscall(__NR_getppid));
        /* No ptracer */
        EXPECT_EQ(-1, syscall(__NR_getpid));
}

TEST_F(precedence, log_is_fifth)
{
        pid_t mypid, parent;
        long ret;

        mypid = getpid();
        parent = getppid();
        ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
        ASSERT_EQ(0, ret);

        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->allow);
        ASSERT_EQ(0, ret);
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->log);
        ASSERT_EQ(0, ret);
        /* Should work just fine. */
        EXPECT_EQ(parent, syscall(__NR_getppid));
        /* Should also work just fine */
        EXPECT_EQ(mypid, syscall(__NR_getpid));
}

TEST_F(precedence, log_is_fifth_in_any_order)
{
        pid_t mypid, parent;
        long ret;

        mypid = getpid();
        parent = getppid();
        ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
        ASSERT_EQ(0, ret);

        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->log);
        ASSERT_EQ(0, ret);
        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->allow);
        ASSERT_EQ(0, ret);
        /* Should work just fine. */
        EXPECT_EQ(parent, syscall(__NR_getppid));
        /* Should also work just fine */
        EXPECT_EQ(mypid, syscall(__NR_getpid));
}

#ifndef PTRACE_O_TRACESECCOMP
#define PTRACE_O_TRACESECCOMP   0x00000080
#endif

/* Catch the Ubuntu 12.04 value error. */
#if PTRACE_EVENT_SECCOMP != 7
#undef PTRACE_EVENT_SECCOMP
#endif

#ifndef PTRACE_EVENT_SECCOMP
#define PTRACE_EVENT_SECCOMP 7
#endif

#define IS_SECCOMP_EVENT(status) ((status >> 16) == PTRACE_EVENT_SECCOMP)
bool tracer_running;
void tracer_stop(int sig)
{
        tracer_running = false;
}

typedef void tracer_func_t(struct __test_metadata *_metadata,
                           pid_t tracee, int status, void *args);

void start_tracer(struct __test_metadata *_metadata, int fd, pid_t tracee,
            tracer_func_t tracer_func, void *args, bool ptrace_syscall)
{
        int ret = -1;
        struct sigaction action = {
                .sa_handler = tracer_stop,
        };

        /* Allow external shutdown. */
        tracer_running = true;
        ASSERT_EQ(0, sigaction(SIGUSR1, &action, NULL));

        errno = 0;
        while (ret == -1 && errno != EINVAL)
                ret = ptrace(PTRACE_ATTACH, tracee, NULL, 0);
        ASSERT_EQ(0, ret) {
                kill(tracee, SIGKILL);
        }
        /* Wait for attach stop */
        wait(NULL);

        ret = ptrace(PTRACE_SETOPTIONS, tracee, NULL, ptrace_syscall ?
                                                      PTRACE_O_TRACESYSGOOD :
                                                      PTRACE_O_TRACESECCOMP);
        ASSERT_EQ(0, ret) {
                TH_LOG("Failed to set PTRACE_O_TRACESECCOMP");
                kill(tracee, SIGKILL);
        }
        ret = ptrace(ptrace_syscall ? PTRACE_SYSCALL : PTRACE_CONT,
                     tracee, NULL, 0);
        ASSERT_EQ(0, ret);

        /* Unblock the tracee */
        ASSERT_EQ(1, write(fd, "A", 1));
        ASSERT_EQ(0, close(fd));

        /* Run until we're shut down. Must assert to stop execution. */
        while (tracer_running) {
                int status;

                if (wait(&status) != tracee)
                        continue;
                if (WIFSIGNALED(status) || WIFEXITED(status))
                        /* Child is dead. Time to go. */
                        return;

                /* Check if this is a seccomp event. */
                ASSERT_EQ(!ptrace_syscall, IS_SECCOMP_EVENT(status));

                tracer_func(_metadata, tracee, status, args);

                ret = ptrace(ptrace_syscall ? PTRACE_SYSCALL : PTRACE_CONT,
                             tracee, NULL, 0);
                ASSERT_EQ(0, ret);
        }
        /* Directly report the status of our test harness results. */
        syscall(__NR_exit, _metadata->passed ? EXIT_SUCCESS : EXIT_FAILURE);
}

/* Common tracer setup/teardown functions. */
void cont_handler(int num)
{ }
pid_t setup_trace_fixture(struct __test_metadata *_metadata,
                          tracer_func_t func, void *args, bool ptrace_syscall)
{
        char sync;
        int pipefd[2];
        pid_t tracer_pid;
        pid_t tracee = getpid();

        /* Setup a pipe for clean synchronization. */
        ASSERT_EQ(0, pipe(pipefd));

        /* Fork a child which we'll promote to tracer */
        tracer_pid = fork();
        ASSERT_LE(0, tracer_pid);
        signal(SIGALRM, cont_handler);
        if (tracer_pid == 0) {
                close(pipefd[0]);
                start_tracer(_metadata, pipefd[1], tracee, func, args,
                             ptrace_syscall);
                syscall(__NR_exit, 0);
        }
        close(pipefd[1]);
        prctl(PR_SET_PTRACER, tracer_pid, 0, 0, 0);
        read(pipefd[0], &sync, 1);
        close(pipefd[0]);

        return tracer_pid;
}

void teardown_trace_fixture(struct __test_metadata *_metadata,
                            pid_t tracer)
{
        if (tracer) {
                int status;
                /*
                 * Extract the exit code from the other process and
                 * adopt it for ourselves in case its asserts failed.
                 */
                ASSERT_EQ(0, kill(tracer, SIGUSR1));
                ASSERT_EQ(tracer, waitpid(tracer, &status, 0));
                if (WEXITSTATUS(status))
                        _metadata->passed = 0;
        }
}

/* "poke" tracer arguments and function. */
struct tracer_args_poke_t {
        unsigned long poke_addr;
};

void tracer_poke(struct __test_metadata *_metadata, pid_t tracee, int status,
                 void *args)
{
        int ret;
        unsigned long msg;
        struct tracer_args_poke_t *info = (struct tracer_args_poke_t *)args;

        ret = ptrace(PTRACE_GETEVENTMSG, tracee, NULL, &msg);
        EXPECT_EQ(0, ret);
        /* If this fails, don't try to recover. */
        ASSERT_EQ(0x1001, msg) {
                kill(tracee, SIGKILL);
        }
        /*
         * Poke in the message.
         * Registers are not touched to try to keep this relatively arch
         * agnostic.
         */
        ret = ptrace(PTRACE_POKEDATA, tracee, info->poke_addr, 0x1001);
        EXPECT_EQ(0, ret);
}

FIXTURE(TRACE_poke) {
        struct sock_fprog prog;
        pid_t tracer;
        long poked;
        struct tracer_args_poke_t tracer_args;
};

FIXTURE_SETUP(TRACE_poke)
{
        struct sock_filter filter[] = {
                BPF_STMT(BPF_LD|BPF_W|BPF_ABS,
                        offsetof(struct seccomp_data, nr)),
                BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, __NR_read, 0, 1),
                BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_TRACE | 0x1001),
                BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),
        };

        self->poked = 0;
        memset(&self->prog, 0, sizeof(self->prog));
        self->prog.filter = malloc(sizeof(filter));
        ASSERT_NE(NULL, self->prog.filter);
        memcpy(self->prog.filter, filter, sizeof(filter));
        self->prog.len = (unsigned short)ARRAY_SIZE(filter);

        /* Set up tracer args. */
        self->tracer_args.poke_addr = (unsigned long)&self->poked;

        /* Launch tracer. */
        self->tracer = setup_trace_fixture(_metadata, tracer_poke,
                                           &self->tracer_args, false);
}

FIXTURE_TEARDOWN(TRACE_poke)
{
        teardown_trace_fixture(_metadata, self->tracer);
        if (self->prog.filter)
                free(self->prog.filter);
}

TEST_F(TRACE_poke, read_has_side_effects)
{
        ssize_t ret;

        ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
        ASSERT_EQ(0, ret);

        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->prog, 0, 0);
        ASSERT_EQ(0, ret);

        EXPECT_EQ(0, self->poked);
        ret = read(-1, NULL, 0);
        EXPECT_EQ(-1, ret);
        EXPECT_EQ(0x1001, self->poked);
}

TEST_F(TRACE_poke, getpid_runs_normally)
{
        long ret;

        ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
        ASSERT_EQ(0, ret);

        ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->prog, 0, 0);
        ASSERT_EQ(0, ret);

        EXPECT_EQ(0, self->poked);
        EXPECT_NE(0, syscall(__NR_getpid));
        EXPECT_EQ(0, self->poked);
}

#if defined(__x86_64__)
# define ARCH_REGS              struct user_regs_struct
# define SYSCALL_NUM(_regs)     (_regs).orig_rax
# define SYSCALL_RET(_regs)     (_regs).rax
#elif defined(__i386__)
# define ARCH_REGS              struct user_regs_struct
# define SYSCALL_NUM(_regs)     (_regs).orig_eax
# define SYSCALL_RET(_regs)     (_regs).eax
#elif defined(__arm__)
# define ARCH_REGS              struct pt_regs
# define SYSCALL_NUM(_regs)     (_regs).ARM_r7
# ifndef PTRACE_SET_SYSCALL
#  define PTRACE_SET_SYSCALL   23
# endif
# define SYSCALL_NUM_SET(_regs, _nr)    \
                EXPECT_EQ(0, ptrace(PTRACE_SET_SYSCALL, tracee, NULL, _nr))
# define SYSCALL_RET(_regs)     (_regs).ARM_r0
#elif defined(__aarch64__)
# define ARCH_REGS              struct user_pt_regs
# define SYSCALL_NUM(_regs)     (_regs).regs[8]
# ifndef NT_ARM_SYSTEM_CALL
#  define NT_ARM_SYSTEM_CALL 0x404
# endif
# define SYSCALL_NUM_SET(_regs, _nr)                            \
        do {                                                    \
                struct iovec __v;                               \
                typeof(_nr) __nr = (_nr);                       \
                __v.iov_base = &__nr;                           \
                __v.iov_len = sizeof(__nr);                     \
                EXPECT_EQ(0, ptrace(PTRACE_SETREGSET, tracee,   \
                                    NT_ARM_SYSTEM_CALL, &__v)); \
        } while (0)
# define SYSCALL_RET(_regs)     (_regs).regs[0]
#elif defined(__riscv) && __riscv_xlen == 64
# define ARCH_REGS              struct user_regs_struct
# define SYSCALL_NUM(_regs)     (_regs).a7
# define SYSCALL_RET(_regs)     (_regs).a0
#elif defined(__csky__)
# define ARCH_REGS              struct pt_regs
#  if defined(__CSKYABIV2__)
#   define SYSCALL_NUM(_regs)   (_regs).regs[3]
#  else
#   define SYSCALL_NUM(_regs)   (_regs).regs[9]
#  endif
# define SYSCALL_RET(_regs)     (_regs).a0
#elif defined(__hppa__)
# define ARCH_REGS              struct user_regs_struct
# define SYSCALL_NUM(_regs)     (_regs).gr[20]
# define SYSCALL_RET(_regs)     (_regs).gr[28]
#elif defined(__powerpc__)
# define ARCH_REGS              struct pt_regs
# define SYSCALL_NUM(_regs)     (_regs).gpr[0]
# define SYSCALL_RET(_regs)     (_regs).gpr[3]
# define SYSCALL_RET_SET(_regs, _val)                           \
        do {                                                    \
                typeof(_val) _result = (_val);                  \
                if ((_regs.trap & 0xfff0) == 0x3000) {          \
                        /*                                      \
                         * scv 0 system call uses -ve result    \
                         * for error, so no need to adjust.     \
                         */                                     \
                        SYSCALL_RET(_regs) = _result;           \
                } else {                                        \
                        /*                                      \
                         * A syscall error is signaled by the   \
                         * CR0 SO bit and the code is stored as \
                         * a positive value.                    \
                         */                                     \
                        if (_result < 0) {                      \
                                SYSCALL_RET(_regs) = -_result;  \
                                (_regs).ccr |= 0x10000000;      \
                        } else {                                \
                                SYSCALL_RET(_regs) = _result;   \
                                (_regs).ccr &= ~0x10000000;     \
                        }                                       \
                }                                               \
        } while (0)
# define SYSCALL_RET_SET_ON_PTRACE_EXIT
#elif defined(__s390__)
# define ARCH_REGS              s390_regs
# define SYSCALL_NUM(_regs)     (_regs).gprs[2]
# define SYSCALL_RET_SET(_regs, _val)                   \
                TH_LOG("Can't modify syscall return on this architecture")
#elif defined(__mips__)
# include <asm/unistd_nr_n32.h>
# include <asm/unistd_nr_n64.h>
# include <asm/unistd_nr_o32.h>
# define ARCH_REGS              struct pt_regs
# define SYSCALL_NUM(_regs)                             \
        ({                                              \
                typeof((_regs).regs[2]) _nr;            \
                if ((_regs).regs[2] == __NR_O32_Linux)  \
                        _nr = (_regs).regs[4];          \
                else                                    \
                        _nr = (_regs).regs[2];          \
                _nr;                                    \
        })
# define SYSCALL_NUM_SET(_regs, _nr)                    \
        do {                                            \
                if ((_regs).regs[2] == __NR_O32_Linux)  \
                        (_regs).regs[4] = _nr;          \
                else                                    \
                        (_regs).regs[2] = _nr;          \
        } while (0)
# define SYSCALL_RET_SET(_regs, _val)                   \
                TH_LOG("Can't modify syscall return on this architecture")
#elif defined(__xtensa__)
# define ARCH_REGS              struct user_pt_regs
# define SYSCALL_NUM(_regs)     (_regs).syscall
/*
 * On xtensa syscall return value is in the register
 * a2 of the current window which is not fixed.
 */
#define SYSCALL_RET(_regs)      (_regs).a[(_regs).windowbase * 4 + 2]
#elif defined(__sh__)
# define ARCH_REGS              struct pt_regs
# define SYSCALL_NUM(_regs)     (_regs).regs[3]
# define SYSCALL_RET(_regs)     (_regs).regs[0]
#else
# error "Do not know how to find your architecture's registers and syscalls"
#endif

/*
 * Most architectures can change the syscall by just updating the
 * associated register. This is the default if not defined above.
 */
#ifndef SYSCALL_NUM_SET
# define SYSCALL_NUM_SET(_regs, _nr)            \
        do {                                    \
                SYSCALL_NUM(_regs) = (_nr);     \
        } while (0)
#endif
/*
 * Most architectures can change the syscall return value by just
 * writing to the SYSCALL_RET register. This is the default if not
 * defined above. If an architecture cannot set the return value
 * (for example when the syscall and return value register is
 * shared), report it with TH_LOG() in an arch-specific definition
 * of SYSCALL_RET_SET() above, and leave SYSCALL_RET undefined.
 */
#if !defined(SYSCALL_RET) && !defined(SYSCALL_RET_SET)
# error "One of SYSCALL_RET or SYSCALL_RET_SET is needed for this arch"
#endif
#ifndef SYSCALL_RET_SET
# define SYSCALL_RET_SET(_regs, _val)           \
        do {                                    \
                SYSCALL_RET(_regs) = (_val);    \
        } while (0)
#endif

/* When the syscall return can't be changed, stub out the tests for it. */
#ifndef SYSCALL_RET
# define EXPECT_SYSCALL_RETURN(val, action)     EXPECT_EQ(-1, action)
#else
# define EXPECT_SYSCALL_RETURN(val, action)             \
        do {                                            \
                errno = 0;                              \
                if (val < 0) {                          \
                        EXPECT_EQ(-1, action);          \
                        EXPECT_EQ(-(val), errno);       \
                } else {                                \
                        EXPECT_EQ(val, action);         \
                }                                       \
        } while (0)
#endif

/*
 * Some architectures (e.g. powerpc) can only set syscall
 * return values on syscall exit during ptrace.
 */
const bool ptrace_entry_set_syscall_nr = true;
const bool ptrace_entry_set_syscall_ret =
#ifndef SYSCALL_RET_SET_ON_PTRACE_EXIT
        true;
#else
        false;
#endif

/*
 * Use PTRACE_GETREGS and PTRACE_SETREGS when available. This is useful for
 * architectures without HAVE_ARCH_TRACEHOOK (e.g. User-mode Linux).
 */
#if defined(__x86_64__) || defined(__i386__) || defined(__mips__)
# define ARCH_GETREGS(_regs)    ptrace(PTRACE_GETREGS, tracee, 0, &(_regs))
# define ARCH_SETREGS(_regs)    ptrace(PTRACE_SETREGS, tracee, 0, &(_regs))
#else
# define ARCH_GETREGS(_regs)    ({                                      \
                struct iovec __v;                                       \
                __v.iov_base = &(_regs);                                \
                __v.iov_len = sizeof(_regs);                            \
                ptrace(PTRACE_GETREGSET, tracee, NT_PRSTATUS, &__v);    \
        })
# define ARCH_SETREGS(_regs)    ({                                      \
                struct iovec __v;                                       \
                __v.iov_base = &(_regs);                                \
                __v.iov_len = sizeof(_regs);                            \
                ptrace(PTRACE_SETREGSET, tracee, NT_PRSTATUS, &__v);    \
        })
#endif

/* Architecture-specific syscall fetching routine. */
int get_syscall(struct __test_metadata *_metadata, pid_t tracee)
{
        ARCH_REGS regs;

        EXPECT_EQ(0, ARCH_GETREGS(regs)) {
                return -1;
        }

        return SYSCALL_NUM(regs);
}

/* Architecture-specific syscall changing routine. */
void __change_syscall(struct __test_metadata *_metadata,
                    pid_t tracee, long *syscall, long *ret)
{
        ARCH_REGS orig, regs;

        /* Do not get/set registers if we have nothing to do. */
        if (!syscall && !ret)
                return;

        EXPECT_EQ(0, ARCH_GETREGS(regs)) {
                return;
        }
        orig = regs;

        if (syscall)
                SYSCALL_NUM_SET(regs, *syscall);

        if (ret)
                SYSCALL_RET_SET(regs, *ret);

        /* Flush any register changes made. */
        if (memcmp(&orig, &regs, sizeof(orig)) != 0)
                EXPECT_EQ(0, ARCH_SETREGS(regs));
}

/* Change only syscall number. */
void change_syscall_nr(struct __test_metadata *_metadata,
                       pid_t tracee, long syscall)
{
        __change_syscall(_metadata, tracee, &syscall, NULL);
}

/* Change syscall return value (and set syscall number to -1). */
void change_syscall_ret(struct __test_metadata *_metadata,
                        pid_t tracee, long ret)
{
        long syscall = -1;

        __change_syscall(_metadata, tracee, &syscall, &ret);
}

void tracer_seccomp(struct __test_metadata *_metadata, pid_t tracee,
                    int status, void *args)
{
        int ret;
        unsigned long msg;

        /* Make sure we got the right message. */
        ret = ptrace(PTRACE_GETEVENTMSG, tracee, NULL, &msg);
        EXPECT_EQ(0, ret);

        /* Validate and take action on expected syscalls. */
        switch (msg) {
        case 0x1002:
                /* change getpid to getppid. */
                EXPECT_EQ(__NR_getpid, get_syscall(_metadata, tracee));
                change_syscall_nr(_metadata, tracee, __NR_getppid);
                break;
        case 0x1003:
                /* skip gettid with valid return code. */
                EXPECT_EQ(__NR_gettid, get_syscall(_metadata, tracee));
                change_syscall_ret(_metadata, tracee, 45000);
                break;
        case 0x1004:
                /* skip openat with error. */
                EXPECT_EQ(__NR_openat, get_syscall(_metadata, tracee));
                change_syscall_ret(_metadata, tracee, -ESRCH);
                break;
        case 0x1005:
                /* do nothing (allow getppid) */
                EXPECT_EQ(__NR_getppid, get_syscall(_metadata, tracee));
                break;
        default:
                EXPECT_EQ(0, msg) {
                        TH_LOG("Unknown PTRACE_GETEVENTMSG: 0x%lx", msg);
                        kill(tracee, SIGKILL);
                }
        }

}

FIXTURE(TRACE_syscall) {
        struct sock_fprog prog;
        pid_t tracer, mytid, mypid, parent;