Re: [PATCH v3 3/3] x86: Add test for arch_prctl(ARCH_VSYSCALL_CONTROL)
From: Andy Lutomirski
Date: Thu Jan 13 2022 - 16:31:21 EST
On 1/5/22 08:03, Florian Weimer wrote:
Signed-off-by: Florian Weimer <fweimer@xxxxxxxxxx>
This seems like a respectable test case, but why does it work so hard to
avoid using libc? Is there something I shuold know about glibc that
makes its maintainer not want to use it :-p
--Andy
---
v3: Patch split out.
tools/arch/x86/include/uapi/asm/prctl.h | 2 +
tools/testing/selftests/x86/Makefile | 7 +-
.../testing/selftests/x86/vsyscall_control.c | 891 ++++++++++++++++++
3 files changed, 899 insertions(+), 1 deletion(-)
create mode 100644 tools/testing/selftests/x86/vsyscall_control.c
diff --git a/tools/arch/x86/include/uapi/asm/prctl.h b/tools/arch/x86/include/uapi/asm/prctl.h
index 754a07856817..aad0bcfbf49f 100644
--- a/tools/arch/x86/include/uapi/asm/prctl.h
+++ b/tools/arch/x86/include/uapi/asm/prctl.h
@@ -18,4 +18,6 @@
#define ARCH_MAP_VDSO_32 0x2002
#define ARCH_MAP_VDSO_64 0x2003
+#define ARCH_VSYSCALL_CONTROL 0x5001
+
#endif /* _ASM_X86_PRCTL_H */
diff --git a/tools/testing/selftests/x86/Makefile b/tools/testing/selftests/x86/Makefile
index 0993d12f2c38..4c751836bfeb 100644
--- a/tools/testing/selftests/x86/Makefile
+++ b/tools/testing/selftests/x86/Makefile
@@ -18,7 +18,7 @@ TARGETS_C_32BIT_ONLY := entry_from_vm86 test_syscall_vdso unwind_vdso \
test_FCMOV test_FCOMI test_FISTTP \
vdso_restorer
TARGETS_C_64BIT_ONLY := fsgsbase sysret_rip syscall_numbering \
- corrupt_xstate_header amx
+ corrupt_xstate_header amx vsyscall_control
# Some selftests require 32bit support enabled also on 64bit systems
TARGETS_C_32BIT_NEEDED := ldt_gdt ptrace_syscall
@@ -107,3 +107,8 @@ $(OUTPUT)/test_syscall_vdso_32: thunks_32.S
# state.
$(OUTPUT)/check_initial_reg_state_32: CFLAGS += -Wl,-ereal_start -static
$(OUTPUT)/check_initial_reg_state_64: CFLAGS += -Wl,-ereal_start -static
+
+# This test does not link against anything (neither libc nor libgcc).
+$(OUTPUT)/vsyscall_control_64: \
+ LIBS := -Wl,-no-pie -static -nostdlib -nostartfiles
+ CFLAGS += -fno-pie -fno-stack-protector -fno-builtin -ffreestanding
diff --git a/tools/testing/selftests/x86/vsyscall_control.c b/tools/testing/selftests/x86/vsyscall_control.c
new file mode 100644
index 000000000000..ee966f936c89
--- /dev/null
+++ b/tools/testing/selftests/x86/vsyscall_control.c
@@ -0,0 +1,891 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * vsyscall_lockout.c - check that disabling vsyscall works
+ * Copyright (C) 2021 Red Hat, Inc.
+ *
+ * This test requires vsyscall=xonly or vsyscall=emulate. With
+ * vsyscall=emulate, ARCH_VSYSCALL_CONTROL cannot turn off vsyscall
+ * completely (reads still work), but this is not tested here.
+ */
+
+#include <stddef.h>
+
+#include <asm/prctl.h>
+#include <asm/vsyscall.h>
+#include <linux/errno.h>
+#include <linux/fcntl.h>
+#include <linux/signal.h>
+#include <linux/time.h>
+#include <linux/types.h>
+#include <linux/unistd.h>
+
+#ifndef ARCH_VSYSCALL_CONTROL
+#define ARCH_VSYSCALL_CONTROL 0x5001
+#elif ARCH_VSYSCALL_CONTROL != 0x5001
+#error wrong vlaue for ARCH_VSYSCALL_CONTROL
+#endif
+
+
+static inline long syscall0(int nr)
+{
+ unsigned long result;
+
+ __asm__ volatile ("syscall"
+ : "=a" (result)
+ : "0" (nr)
+ : "memory", "cc", "r11", "cx");
+ return result;
+}
+
+static inline long syscall1(int nr, long arg0)
+{
+ register long rdi asm("rdi") = arg0;
+ unsigned long result;
+
+ __asm__ volatile ("syscall"
+ : "=a" (result)
+ : "0" (nr), "r" (rdi)
+ : "memory", "cc", "r11", "cx");
+ return result;
+}
+
+static inline long syscall2(int nr, long arg0, long arg1)
+{
+ register long rdi asm("rdi") = arg0;
+ register long rsi asm("rsi") = arg1;
+ unsigned long result;
+
+ __asm__ volatile ("syscall"
+ : "=a" (result)
+ : "0" (nr), "r" (rdi), "r" (rsi)
+ : "memory", "cc", "r11", "cx");
+ return result;
+}
+
+static inline long syscall3(int nr, long arg0, long arg1, long arg2)
+{
+ register long rdi asm("rdi") = arg0;
+ register long rsi asm("rsi") = arg1;
+ register long rdx asm("rdx") = arg2;
+ unsigned long result;
+
+ __asm__ volatile ("syscall"
+ : "=a" (result)
+ : "0" (nr), "r" (rdi), "r" (rsi), "r" (rdx)
+ : "memory", "cc", "r11", "cx");
+ return result;
+}
+
+static inline long syscall4(int nr, long arg0, long arg1, long arg2, long arg3)
+{
+ register long rdi asm("rdi") = arg0;
+ register long rsi asm("rsi") = arg1;
+ register long rdx asm("rdx") = arg2;
+ register long r10 asm("r10") = arg3;
+ unsigned long result;
+
+ __asm__ volatile ("syscall"
+ : "=a" (result)
+ : "0" (nr), "r" (rdi), "r" (rsi), "r" (rdx),
+ "r" (r10)
+ : "memory", "cc", "r11", "cx");
+ return result;
+}
+
+static inline long syscall5(int nr, long arg0, long arg1, long arg2, long arg3,
+ long arg4)
+{
+ register long rdi asm("rdi") = arg0;
+ register long rsi asm("rsi") = arg1;
+ register long rdx asm("rdx") = arg2;
+ register long r10 asm("r10") = arg3;
+ register long r8 asm("r8") = arg4;
+ unsigned long result;
+
+ __asm__ volatile ("syscall"
+ : "=a" (result)
+ : "0" (nr), "r" (rdi), "r" (rsi), "r" (rdx),
+ "r" (r10), "r" (r8)
+ : "memory", "cc", "r11", "cx");
+ return result;
+}
+
+static inline long vsyscall2(long addr, long arg0, long arg1)
+{
+ register long rdi asm("rdi") = arg0;
+ register long rsi asm("rsi") = arg1;
+ unsigned long result;
+
+ __asm__ volatile ("callq *%%rax"
+ : "=a" (result)
+ : "0" (addr), "r" (rdi), "r" (rsi)
+ : "memory", "cc", "r11", "cx");
+ return result;
+}
+
+static void __attribute__ ((noreturn)) sys_exit(int status)
+{
+ syscall1(__NR_exit, status);
+ __builtin_unreachable();
+}
+
+static int sys_access(const char *pathname, int mode)
+{
+ return syscall2(__NR_access, (long) pathname, mode);
+}
+
+static int sys_mkdir(const char *pathname, __kernel_mode_t mode)
+{
+ return syscall2(__NR_mkdir, (long) pathname, mode);
+}
+
+static int sys_open(const char *pathname, int flags, __kernel_mode_t mode)
+{
+ return syscall3(__NR_open, (long) pathname, flags, mode);
+}
+
+static long sys_read(int fd, void *buffer, size_t length)
+{
+ return syscall3(__NR_read, fd, (long) buffer, length);
+}
+
+static long sys_write(int fd, const void *buffer, size_t length)
+{
+ return syscall3(__NR_write, fd, (long) buffer, length);
+}
+
+static int sys_mount(const char *source, const char *pathname,
+ const char *fstype, unsigned long flags,
+ const void *data)
+{
+ return syscall5(__NR_mount, (long) source, (long) pathname,
+ (long) fstype, flags, (long) data);
+}
+
+static void sigabrt(void)
+{
+ syscall2(__NR_kill, syscall0(__NR_getpid), SIGABRT);
+}
+
+/*
+ * String buffers.
+ */
+
+struct buffer {
+ char *position;
+ char *limit;
+};
+
+static void buffer_init(struct buffer *b, char *start, size_t length)
+{
+ b->position = start;
+ b->limit = start + length;
+}
+
+static void buffer_append(struct buffer *b, char ch)
+{
+ if (b->position >= b->limit)
+ sigabrt();
+ *b->position = ch;
+ ++b->position;
+}
+
+static void buffer_append_string(struct buffer *b, const char *p)
+{
+ while (*p) {
+ buffer_append(b, *p);
+ ++p;
+ }
+}
+
+static void buffer_append_dec_1(struct buffer *b, unsigned long val)
+{
+ if (val != 0) {
+ buffer_append_dec_1(b, val / 10);
+ buffer_append(b, '0' + (val % 10));
+ }
+}
+
+static void buffer_append_dec(struct buffer *b, unsigned long val)
+{
+ if (val == 0) {
+ buffer_append(b, '0');
+ return;
+ }
+ buffer_append_dec_1(b, val);
+}
+
+/*
+ * Output to standard output.
+ */
+
+static void print_char(char byte)
+{
+ if (sys_write(1, &byte, 1) < 0)
+ sigabrt();
+}
+
+static void print_string(const char *p)
+{
+ while (*p) {
+ print_char(*p);
+ ++p;
+ }
+}
+
+static void print_dec_1(unsigned long val)
+{
+ if (val != 0) {
+ print_dec_1(val / 10);
+ print_char('0' + (val % 10));
+ }
+}
+
+static void print_dec(unsigned long val)
+{
+ if (val == 0)
+ print_char('0');
+ else
+ print_dec_1(val);
+}
+
+static void print_signed_dec(long val)
+{
+ if (val < 0) {
+ print_char('-');
+ print_dec(-(unsigned long)val);
+ } else
+ print_dec(val);
+}
+
+static void print_message(unsigned int lineno, const char *tag, const char *p)
+{
+ print_string(__FILE__);
+ print_char(':');
+ print_dec(lineno);
+ print_char(':');
+ print_char(' ');
+ print_string(tag);
+ print_char(':');
+ print_char(' ');
+ print_string(p);
+}
+
+static void print_info(unsigned int lineno, const char *p)
+{
+ print_message(lineno, "info", p);
+}
+
+static void print_error(unsigned int lineno, const char *p)
+{
+ print_message(lineno, "ERROR", p);
+}
+
+static void print_failure(int lineno, const char *label, long ret)
+{
+ print_error(lineno, label);
+ print_string(" failed: ");
+ print_signed_dec(ret);
+ print_char('\n');
+}
+
+static void print_time(int lineno, const char *label, struct timeval tv)
+{
+ print_info(lineno, label);
+ print_string(": ");
+ print_dec(tv.tv_sec);
+ print_char(' ');
+ print_dec(tv.tv_usec);
+ print_char('\n');
+}
+
+/*
+ * Process-failing (v)syscall wrappers.
+ */
+
+static void xgettimeofday(struct timeval *tv)
+{
+ long ret = syscall2(__NR_gettimeofday, (long) tv, 0);
+
+ if (ret != 0) {
+ print_failure(__LINE__, "gettimeofday", ret);
+ sigabrt();
+ }
+}
+
+static void xvgettimeofday(struct timeval *tv)
+{
+ long ret = vsyscall2(VSYSCALL_ADDR, (long) tv, 0);
+
+ if (ret) {
+ print_failure(__LINE__, "vgettimeofday", ret);
+ sigabrt();
+ }
+}
+
+static int sys_arch_prctl(int code, unsigned long addr)
+{
+ return syscall2(__NR_arch_prctl, code, addr);
+}
+
+static void xclose(int fd)
+{
+ long ret = syscall1(__NR_close, fd);
+
+ if (ret < 0) {
+ print_failure(__LINE__, "close", ret);
+ sigabrt();
+ }
+}
+
+static void xwrite_byte(int fd, char b)
+{
+ long ret = sys_write(fd, &b, 1);
+
+ if (ret != 1) {
+ print_failure(__LINE__, "write", ret);
+ sigabrt();
+ }
+}
+
+static int xread_byte(int fd)
+{
+ char b;
+ long ret = sys_read(fd, &b, 1);
+
+ if (ret != 1) {
+ print_failure(__LINE__, "read", ret);
+ sigabrt();
+ }
+ return b;
+}
+
+static void xpipe(int fds[static 2])
+{
+ long ret = syscall2(__NR_pipe2, (long) fds, O_CLOEXEC);
+
+ if (ret != 0) {
+ print_failure(__LINE__, "pipe2", ret);
+ sigabrt();
+ }
+}
+
+static __kernel_pid_t xfork(void)
+{
+ long ret = syscall0(__NR_fork);
+
+ if (ret < 0) {
+ print_failure(__LINE__, "fork", ret);
+ sigabrt();
+ }
+ return ret;
+}
+
+static void xexecve(const char *pathname, char **argv, char **envp)
+{
+ long ret;
+
+ ret = syscall3(__NR_execve, (long) pathname, (long) argv, (long) envp);
+ print_failure(__LINE__, "execve", ret);
+ sigabrt();
+}
+
+static __kernel_pid_t xwaitpid(__kernel_pid_t pid, int *status, int options)
+{
+ long ret = syscall4(__NR_wait4, pid, (long) status, options, 0);
+
+ if (ret < 0) {
+ print_failure(__LINE__, "wait4", ret);
+ sigabrt();
+ }
+ return ret;
+}
+
+/*
+ * Various helpers.
+ */
+
+static void vsyscall_disable(void)
+{
+ long ret = sys_arch_prctl(ARCH_VSYSCALL_CONTROL, 0);
+
+ if (ret != 0)
+ print_failure(__LINE__, "arch_prctl(ARCH_VSYSCALL_CONTROL, 0)", ret);
+}
+
+static void vsyscall_enable(void)
+{
+ long ret = sys_arch_prctl(ARCH_VSYSCALL_CONTROL, 1);
+
+ if (ret != 0)
+ print_failure(__LINE__, "arch_prctl(ARCH_VSYSCALL_CONTROL, 1)", ret);
+}
+
+static long difftime(struct timeval first, struct timeval second)
+{
+ return second.tv_usec - first.tv_usec +
+ (second.tv_sec - first.tv_sec) * 1000 * 1000;
+}
+
+static void ensure_proc_is_mounted(int *status)
+{
+ int ret;
+
+ if (sys_access("/proc/version", 0) == 0)
+ return;
+
+ ret = sys_mkdir("/proc", 0555);
+ if (ret == EEXIST)
+ return;
+ if (ret != 0) {
+ print_failure(__LINE__, "could not create /proc", ret);
+ *status = 1;
+ return;
+ }
+ ret = sys_mount("none", "/proc", "proc", 0, NULL);
+ if (ret != 0) {
+ print_failure(__LINE__, "could not mount /proc", ret);
+ *status = 1;
+ return;
+ }
+ if (sys_access("/proc/version", 0) != 0) {
+ print_error(__LINE__, "no /proc/version after mounting /proc");
+ *status = 1;
+ return;
+ }
+}
+
+/*
+ * Individual subtest functions.
+ */
+
+static void check_time(int *status)
+{
+ struct timeval initial_time = { -1, -1 };
+ struct timeval vsyscall_time = { -1, -1 };
+ struct timeval final_time = { -1, -1 };
+ long vsyscall_diff, final_diff;
+
+ xgettimeofday(&initial_time);
+ xvgettimeofday(&vsyscall_time);
+ xgettimeofday(&final_time);
+ vsyscall_diff = difftime(initial_time, vsyscall_time);
+ final_diff = difftime(vsyscall_time, final_time);
+
+ print_time(__LINE__, "initial gettimeofday", initial_time);
+ print_time(__LINE__, "vsyscall gettimeofday", vsyscall_time);
+ print_time(__LINE__, "final gettimeofday", final_time);
+
+ if (initial_time.tv_sec < 0 || initial_time.tv_usec < 0 ||
+ vsyscall_time.tv_sec < 0 || vsyscall_time.tv_usec < 0 ||
+ final_time.tv_sec < 0 || final_time.tv_usec < 0) {
+ print_error(__LINE__, "negative time\n");
+ *status = 1;
+ }
+
+ print_info(__LINE__, "differences: ");
+ print_signed_dec(vsyscall_diff);
+ print_char(' ');
+ print_signed_dec(final_diff);
+ print_char('\n');
+
+ if (vsyscall_diff < 0 || final_diff < 0) {
+ /*
+ * This may produce false positives if there is an active NTP.
+ */
+ print_error(__LINE__, "time went backwards\n");
+ *status = 1;
+ }
+}
+
+static void check_lockout_after_fork(int *status, int twice)
+{
+ __kernel_pid_t pid;
+ struct timeval vsyscall_time;
+ int wstatus;
+
+ if (twice) {
+ __kernel_pid_t pid_outer;
+
+ print_info(__LINE__, "checking that lockout is inherited by fork\n");
+
+ pid_outer = xfork();
+ if (pid_outer == 0) {
+ vsyscall_disable();
+ /*
+ * Logic for the subprocess follows below.
+ */
+ } else {
+ xwaitpid(pid_outer, &wstatus, 0);
+ if (wstatus != 0) {
+ print_error(__LINE__, "unexpected exit status: ");
+ print_signed_dec(wstatus);
+ print_char('\n');
+ *status = 1;
+ }
+ return;
+ }
+ } else
+ print_info(__LINE__, "checking that lockout works after one fork\n");
+
+ pid = xfork();
+ if (pid == 0) {
+ if (!twice)
+ vsyscall_disable();
+ /*
+ * This should trigger a fault.
+ */
+ xvgettimeofday(&vsyscall_time);
+ sys_exit(0);
+ }
+ xwaitpid(pid, &wstatus, 0);
+ switch (wstatus) {
+ case 0:
+ print_error(__LINE__, "no crash after lockout\n");
+ *status = 1;
+ break;
+ case 0x0100:
+ *status = 1;
+ break;
+ case SIGSEGV:
+ print_info(__LINE__, "termination after lockout\n");
+ break;
+ default:
+ print_error(__LINE__, "unexpected exit status: ");
+ print_signed_dec(wstatus);
+ print_char('\n');
+ *status = 1;
+ }
+
+ if (twice)
+ sys_exit(*status);
+
+ /*
+ * Status in the parent process should be unaffected.
+ */
+ xvgettimeofday(&vsyscall_time);
+}
+
+static void check_no_lockout_after_enable(int *status)
+{
+ __kernel_pid_t pid;
+ struct timeval vsyscall_time;
+ int wstatus;
+
+ print_info(__LINE__, "checking that vsyscall can be re-enabled\n");
+
+ pid = xfork();
+ if (pid == 0) {
+ vsyscall_disable();
+ vsyscall_enable();
+ xvgettimeofday(&vsyscall_time);
+ print_time(__LINE__, "vsyscall time after re-enable", vsyscall_time);
+ sys_exit(0);
+ }
+
+ xwaitpid(pid, &wstatus, 0);
+ if (wstatus != 0) {
+ print_error(__LINE__, "unexpected exit status: ");
+ print_signed_dec(wstatus);
+ print_char('\n');
+ *status = 1;
+ }
+}
+
+static void check_no_lockout_after_execve(char **argv, int *status)
+{
+ __kernel_pid_t pid;
+ int wstatus;
+
+ print_info(__LINE__, "checking that lockout is not inherited by execve\n");
+ pid = xfork();
+ if (pid == 0) {
+ struct timeval vsyscall_time;
+ char *new_argv[3];
+
+ xvgettimeofday(&vsyscall_time);
+ vsyscall_disable();
+
+ /*
+ * Re-exec the second stage. See main_2 below.
+ */
+ new_argv[0] = argv[0];
+ new_argv[1] = "2";
+ new_argv[2] = NULL;
+ xexecve(argv[0], new_argv, new_argv + 2);
+ }
+
+ xwaitpid(pid, &wstatus, 0);
+ if (wstatus != 0) {
+ print_error(__LINE__, "unexpected exit status: ");
+ print_signed_dec(wstatus);
+ print_char('\n');
+ *status = 1;
+ }
+}
+
+static int has_vsyscall_map(int pid, int *status)
+{
+ int result = 0;
+ char maps_path[50];
+ int fd;
+
+ /*
+ * Construct /proc/PID/maps path.
+ */
+ {
+ struct buffer b;
+
+ buffer_init(&b, maps_path, sizeof(maps_path));
+ buffer_append_string(&b, "/proc/");
+ if (pid == 0)
+ buffer_append_string(&b, "self");
+ else
+ buffer_append_dec(&b, pid);
+ buffer_append_string(&b, "/maps");
+ buffer_append(&b, 0);
+ }
+
+ fd = sys_open(maps_path, O_RDONLY, 0);
+ if (fd < 0) {
+ print_error(__LINE__, "maps file ");
+ print_string(maps_path);
+ print_string(": ");
+ print_signed_dec(fd);
+ print_char('\n');
+ *status = 1;
+ }
+
+ /*
+ * Search for "[vsyscall]\n".
+ */
+ {
+ char buf[4096];
+ long ret;
+
+ for (size_t i = 0; i < sizeof(buf); ++i)
+ buf[i] = 0;
+ ret = sys_read(fd, buf, sizeof(buf));
+
+ if (ret < 0 || ret >= sizeof(buf))
+ print_failure(__LINE__, "read", ret);
+ else {
+ char *bracket = buf;
+
+ while (1) {
+ while (*bracket && *bracket != '[')
+ ++bracket;
+ if (*bracket != '[')
+ /*
+ * End of file has been reached.
+ */
+ break;
+ ++bracket;
+ if (bracket[0] == 'v'
+ && bracket[1] == 's'
+ && bracket[2] == 'y'
+ && bracket[3] == 's'
+ && bracket[4] == 'c'
+ && bracket[5] == 'a'
+ && bracket[6] == 'l'
+ && bracket[7] == 'l'
+ && bracket[8] == ']'
+ && bracket[9] == '\n') {
+ result = 1;
+ break;
+ }
+ }
+ }
+ }
+
+ xclose(fd);
+ return result;
+}
+
+static void check_vsyscall_in_self_maps(int *status)
+{
+ __kernel_pid_t pid;
+ int wstatus;
+
+ print_info(__LINE__, "checking [vsyscall] in /proc/self/maps\n");
+
+ pid = xfork();
+ if (pid == 0) {
+ if (!has_vsyscall_map(0, status)) {
+ print_error(__LINE__, "[vsyscall] missing\n");
+ *status = 1;
+ }
+ vsyscall_disable();
+ if (has_vsyscall_map(0, status)) {
+ print_error(__LINE__, "[vsyscall] present after disable\n");
+ *status = 1;
+ }
+ vsyscall_enable();
+ if (!has_vsyscall_map(0, status)) {
+ print_error(__LINE__, "[vsyscall] missing after enable\n");
+ *status = 1;
+ }
+ sys_exit(*status);
+ }
+
+ xwaitpid(pid, &wstatus, 0);
+ if (wstatus != 0) {
+ print_error(__LINE__, "unexpected exit status: ");
+ print_signed_dec(wstatus);
+ print_char('\n');
+ *status = 1;
+ }
+}
+
+static void check_vsyscall_maps_for_subprocess(int *status)
+{
+ __kernel_pid_t pid;
+ int wstatus;
+ int outer_to_inner[2];
+ int inner_to_outer[2];
+
+ /*
+ * Create pipes used to synchronize the two processes.
+ */
+ xpipe(outer_to_inner);
+ xpipe(inner_to_outer);
+
+ print_info(__LINE__, "checking [vsyscall] in /proc/PID/maps\n");
+
+ pid = xfork();
+ if (pid == 0) {
+ xclose(outer_to_inner[1]);
+ xclose(inner_to_outer[0]);
+
+ xread_byte(outer_to_inner[0]);
+ vsyscall_disable();
+ xwrite_byte(inner_to_outer[1], 101);
+
+ xread_byte(outer_to_inner[0]);
+ vsyscall_disable();
+ xwrite_byte(inner_to_outer[1], 102);
+
+ sys_exit(0);
+ }
+
+ xclose(outer_to_inner[0]);
+ xclose(inner_to_outer[1]);
+
+ if (!has_vsyscall_map(pid, status)) {
+ print_error(__LINE__, "subprocess starts without [vsyscall]");
+ *status = 1;
+ }
+
+ xwrite_byte(outer_to_inner[1], 1);
+ xread_byte(inner_to_outer[0]);
+
+ if (has_vsyscall_map(pid, status)) {
+ print_error(__LINE__, "subprocess has [vsyscall] after disable");
+ *status = 1;
+ }
+
+ xwrite_byte(outer_to_inner[1], 2);
+ xread_byte(inner_to_outer[0]);
+
+ if (has_vsyscall_map(pid, status)) {
+ print_error(__LINE__, "subprocess lacks [vsyscall] after enable");
+ *status = 1;
+ }
+
+ xclose(outer_to_inner[1]);
+ xclose(inner_to_outer[0]);
+
+ xwaitpid(pid, &wstatus, 0);
+ if (wstatus != 0) {
+ print_error(__LINE__, "unexpected exit status: ");
+ print_signed_dec(wstatus);
+ print_char('\n');
+ *status = 1;
+ }
+}
+
+static void check_einval(int *status)
+{
+ long ret;
+
+ ret = sys_arch_prctl(ARCH_VSYSCALL_CONTROL, 2);
+ if (ret != -EINVAL) {
+ print_error(__LINE__, "arch_prctl(ARCH_VSYSCALL_CONTROL, 2) returned ");
+ print_signed_dec(ret);
+ print_char('\n');
+ *status = 1;
+ }
+}
+
+/*
+ * Second stage: Check that the lockout is not inherited across execve.
+ * Used from check_no_lockout_after_execve.
+ */
+static int main_2(void)
+{
+ struct timeval vsyscall_time = { -1, -1 };
+ int status = 0;
+
+ xvgettimeofday(&vsyscall_time);
+ print_time(__LINE__, "vsyscall gettimeofday after fork", vsyscall_time);
+ if (vsyscall_time.tv_sec < 0 || vsyscall_time.tv_usec < 0)
+ status = 1;
+
+ return status;
+}
+
+static int main(int argc, char **argv)
+{
+ int status = 0;
+
+ if (argc > 1) {
+ switch (*argv[1]) {
+ case '2':
+ return main_2();
+ default:
+ print_string("usage: ");
+ print_string(argv[0]);
+ print_string("\n");
+ return 1;
+ }
+ }
+
+ ensure_proc_is_mounted(&status);
+
+ if (has_vsyscall_map(0, &status))
+ print_info(__LINE__, "vsyscall active at process start\n");
+ else
+ print_error(__LINE__, "vsyscall inactive at process start\n");
+
+
+ check_time(&status);
+ check_lockout_after_fork(&status, 0);
+ check_lockout_after_fork(&status, 1);
+ check_no_lockout_after_enable(&status);
+ check_no_lockout_after_execve(argv, &status);
+ check_vsyscall_in_self_maps(&status);
+ check_vsyscall_maps_for_subprocess(&status);
+ check_einval(&status);
+
+ print_info(__LINE__, "testing done, exit status: ");
+ print_signed_dec(status);
+ print_char('\n');
+ return status;
+}
+
+static void __attribute__ ((used)) main_trampoline(long *rsp)
+{
+ sys_exit(main(*rsp, (char **) (rsp + 1)));
+}
+
+__asm__(".text\n\t"
+ ".globl _start\n"
+ "_start:\n\t"
+ ".cfi_startproc\n\t"
+ ".cfi_undefined rip\n\t"
+ "movq %rsp, %rdi\n\t"
+ "callq main_trampoline\n\t" /* Results in psABI %rsp alignment. */
+ ".cfi_endproc\n\t"
+ ".type _start, @function\n\t"
+ ".size _start, . - _start\n\t"
+ ".previous");