389 lines
10 KiB
C
389 lines
10 KiB
C
|
/*
|
||
|
|
* Copyright (c) 2022 Alexey Dobriyan <adobriyan@gmail.com>
|
||
|
|
*
|
||
|
|
* Permission to use, copy, modify, and distribute this software for any
|
||
|
|
* purpose with or without fee is hereby granted, provided that the above
|
||
|
|
* copyright notice and this permission notice appear in all copies.
|
||
|
|
*
|
||
|
|
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
|
||
|
|
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
|
||
|
|
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
|
||
|
|
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
|
||
|
|
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
|
||
|
|
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
|
||
|
|
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
|
||
|
|
*/
|
||
|
|
/*
|
||
|
|
* Create a process without mappings by unmapping everything at once and
|
||
|
|
* holding it with ptrace(2). See what happens to
|
||
|
|
*
|
||
|
|
* /proc/${pid}/maps
|
||
|
|
* /proc/${pid}/numa_maps
|
||
|
|
* /proc/${pid}/smaps
|
||
|
|
* /proc/${pid}/smaps_rollup
|
||
|
|
*/
|
||
|
|
#undef NDEBUG
|
||
|
|
#include <assert.h>
|
||
|
|
#include <errno.h>
|
||
|
|
#include <stdint.h>
|
||
|
|
#include <stdio.h>
|
||
|
|
#include <stdlib.h>
|
||
|
|
#include <string.h>
|
||
|
|
#include <fcntl.h>
|
||
|
|
#include <sys/mman.h>
|
||
|
|
#include <sys/ptrace.h>
|
||
|
|
#include <sys/resource.h>
|
||
|
|
#include <sys/types.h>
|
||
|
|
#include <sys/wait.h>
|
||
|
|
#include <unistd.h>
|
||
|
|
|
||
|
|
/*
|
||
|
|
* 0: vsyscall VMA doesn't exist vsyscall=none
|
||
|
|
* 1: vsyscall VMA is --xp vsyscall=xonly
|
||
|
|
* 2: vsyscall VMA is r-xp vsyscall=emulate
|
||
|
|
*/
|
||
|
|
static volatile int g_vsyscall;
|
||
|
|
static const char *g_proc_pid_maps_vsyscall;
|
||
|
|
static const char *g_proc_pid_smaps_vsyscall;
|
||
|
|
|
||
|
|
static const char proc_pid_maps_vsyscall_0[] = "";
|
||
|
|
static const char proc_pid_maps_vsyscall_1[] =
|
||
|
|
"ffffffffff600000-ffffffffff601000 --xp 00000000 00:00 0 [vsyscall]\n";
|
||
|
|
static const char proc_pid_maps_vsyscall_2[] =
|
||
|
|
"ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0 [vsyscall]\n";
|
||
|
|
|
||
|
|
static const char proc_pid_smaps_vsyscall_0[] = "";
|
||
|
|
|
||
|
|
static const char proc_pid_smaps_vsyscall_1[] =
|
||
|
|
"ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0 [vsyscall]\n"
|
||
|
|
"Size: 4 kB\n"
|
||
|
|
"KernelPageSize: 4 kB\n"
|
||
|
|
"MMUPageSize: 4 kB\n"
|
||
|
|
"Rss: 0 kB\n"
|
||
|
|
"Pss: 0 kB\n"
|
||
|
|
"Pss_Dirty: 0 kB\n"
|
||
|
|
"Shared_Clean: 0 kB\n"
|
||
|
|
"Shared_Dirty: 0 kB\n"
|
||
|
|
"Private_Clean: 0 kB\n"
|
||
|
|
"Private_Dirty: 0 kB\n"
|
||
|
|
"Referenced: 0 kB\n"
|
||
|
|
"Anonymous: 0 kB\n"
|
||
|
|
"LazyFree: 0 kB\n"
|
||
|
|
"AnonHugePages: 0 kB\n"
|
||
|
|
"ShmemPmdMapped: 0 kB\n"
|
||
|
|
"FilePmdMapped: 0 kB\n"
|
||
|
|
"Shared_Hugetlb: 0 kB\n"
|
||
|
|
"Private_Hugetlb: 0 kB\n"
|
||
|
|
"Swap: 0 kB\n"
|
||
|
|
"SwapPss: 0 kB\n"
|
||
|
|
"Locked: 0 kB\n"
|
||
|
|
"THPeligible: 0\n"
|
||
|
|
/*
|
||
|
|
* "ProtectionKey:" field is conditional. It is possible to check it as well,
|
||
|
|
* but I don't have such machine.
|
||
|
|
*/
|
||
|
|
;
|
||
|
|
|
||
|
|
static const char proc_pid_smaps_vsyscall_2[] =
|
||
|
|
"ffffffffff600000-ffffffffff601000 --xp 00000000 00:00 0 [vsyscall]\n"
|
||
|
|
"Size: 4 kB\n"
|
||
|
|
"KernelPageSize: 4 kB\n"
|
||
|
|
"MMUPageSize: 4 kB\n"
|
||
|
|
"Rss: 0 kB\n"
|
||
|
|
"Pss: 0 kB\n"
|
||
|
|
"Pss_Dirty: 0 kB\n"
|
||
|
|
"Shared_Clean: 0 kB\n"
|
||
|
|
"Shared_Dirty: 0 kB\n"
|
||
|
|
"Private_Clean: 0 kB\n"
|
||
|
|
"Private_Dirty: 0 kB\n"
|
||
|
|
"Referenced: 0 kB\n"
|
||
|
|
"Anonymous: 0 kB\n"
|
||
|
|
"LazyFree: 0 kB\n"
|
||
|
|
"AnonHugePages: 0 kB\n"
|
||
|
|
"ShmemPmdMapped: 0 kB\n"
|
||
|
|
"FilePmdMapped: 0 kB\n"
|
||
|
|
"Shared_Hugetlb: 0 kB\n"
|
||
|
|
"Private_Hugetlb: 0 kB\n"
|
||
|
|
"Swap: 0 kB\n"
|
||
|
|
"SwapPss: 0 kB\n"
|
||
|
|
"Locked: 0 kB\n"
|
||
|
|
"THPeligible: 0\n"
|
||
|
|
/*
|
||
|
|
* "ProtectionKey:" field is conditional. It is possible to check it as well,
|
||
|
|
* but I'm too tired.
|
||
|
|
*/
|
||
|
|
;
|
||
|
|
|
||
|
|
static void sigaction_SIGSEGV(int _, siginfo_t *__, void *___)
|
||
|
|
{
|
||
|
|
_exit(EXIT_FAILURE);
|
||
|
|
}
|
||
|
|
|
||
|
|
static void sigaction_SIGSEGV_vsyscall(int _, siginfo_t *__, void *___)
|
||
|
|
{
|
||
|
|
_exit(g_vsyscall);
|
||
|
|
}
|
||
|
|
|
||
|
|
/*
|
||
|
|
* vsyscall page can't be unmapped, probe it directly.
|
||
|
|
*/
|
||
|
|
static void vsyscall(void)
|
||
|
|
{
|
||
|
|
pid_t pid;
|
||
|
|
int wstatus;
|
||
|
|
|
||
|
|
pid = fork();
|
||
|
|
if (pid < 0) {
|
||
|
|
fprintf(stderr, "fork, errno %d\n", errno);
|
||
|
|
exit(1);
|
||
|
|
}
|
||
|
|
if (pid == 0) {
|
||
|
|
setrlimit(RLIMIT_CORE, &(struct rlimit){});
|
||
|
|
|
||
|
|
/* Hide "segfault at ffffffffff600000" messages. */
|
||
|
|
struct sigaction act = {};
|
||
|
|
act.sa_flags = SA_SIGINFO;
|
||
|
|
act.sa_sigaction = sigaction_SIGSEGV_vsyscall;
|
||
|
|
sigaction(SIGSEGV, &act, NULL);
|
||
|
|
|
||
|
|
g_vsyscall = 0;
|
||
|
|
/* gettimeofday(NULL, NULL); */
|
||
|
|
uint64_t rax = 0xffffffffff600000;
|
||
|
|
asm volatile (
|
||
|
|
"call *%[rax]"
|
||
|
|
: [rax] "+a" (rax)
|
||
|
|
: "D" (NULL), "S" (NULL)
|
||
|
|
: "rcx", "r11"
|
||
|
|
);
|
||
|
|
|
||
|
|
g_vsyscall = 1;
|
||
|
|
*(volatile int *)0xffffffffff600000UL;
|
||
|
|
|
||
|
|
g_vsyscall = 2;
|
||
|
|
exit(g_vsyscall);
|
||
|
|
}
|
||
|
|
waitpid(pid, &wstatus, 0);
|
||
|
|
if (WIFEXITED(wstatus)) {
|
||
|
|
g_vsyscall = WEXITSTATUS(wstatus);
|
||
|
|
} else {
|
||
|
|
fprintf(stderr, "error: vsyscall wstatus %08x\n", wstatus);
|
||
|
|
exit(1);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
static int test_proc_pid_maps(pid_t pid)
|
||
|
|
{
|
||
|
|
char buf[4096];
|
||
|
|
snprintf(buf, sizeof(buf), "/proc/%u/maps", pid);
|
||
|
|
int fd = open(buf, O_RDONLY);
|
||
|
|
if (fd == -1) {
|
||
|
|
perror("open /proc/${pid}/maps");
|
||
|
|
return EXIT_FAILURE;
|
||
|
|
} else {
|
||
|
|
ssize_t rv = read(fd, buf, sizeof(buf));
|
||
|
|
close(fd);
|
||
|
|
if (g_vsyscall == 0) {
|
||
|
|
assert(rv == 0);
|
||
|
|
} else {
|
||
|
|
size_t len = strlen(g_proc_pid_maps_vsyscall);
|
||
|
|
assert(rv == len);
|
||
|
|
assert(memcmp(buf, g_proc_pid_maps_vsyscall, len) == 0);
|
||
|
|
}
|
||
|
|
return EXIT_SUCCESS;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
static int test_proc_pid_numa_maps(pid_t pid)
|
||
|
|
{
|
||
|
|
char buf[4096];
|
||
|
|
snprintf(buf, sizeof(buf), "/proc/%u/numa_maps", pid);
|
||
|
|
int fd = open(buf, O_RDONLY);
|
||
|
|
if (fd == -1) {
|
||
|
|
if (errno == ENOENT) {
|
||
|
|
/*
|
||
|
|
* /proc/${pid}/numa_maps is under CONFIG_NUMA,
|
||
|
|
* it doesn't necessarily exist.
|
||
|
|
*/
|
||
|
|
return EXIT_SUCCESS;
|
||
|
|
}
|
||
|
|
perror("open /proc/${pid}/numa_maps");
|
||
|
|
return EXIT_FAILURE;
|
||
|
|
} else {
|
||
|
|
ssize_t rv = read(fd, buf, sizeof(buf));
|
||
|
|
close(fd);
|
||
|
|
assert(rv == 0);
|
||
|
|
return EXIT_SUCCESS;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
static int test_proc_pid_smaps(pid_t pid)
|
||
|
|
{
|
||
|
|
char buf[4096];
|
||
|
|
snprintf(buf, sizeof(buf), "/proc/%u/smaps", pid);
|
||
|
|
int fd = open(buf, O_RDONLY);
|
||
|
|
if (fd == -1) {
|
||
|
|
if (errno == ENOENT) {
|
||
|
|
/*
|
||
|
|
* /proc/${pid}/smaps is under CONFIG_PROC_PAGE_MONITOR,
|
||
|
|
* it doesn't necessarily exist.
|
||
|
|
*/
|
||
|
|
return EXIT_SUCCESS;
|
||
|
|
}
|
||
|
|
perror("open /proc/${pid}/smaps");
|
||
|
|
return EXIT_FAILURE;
|
||
|
|
} else {
|
||
|
|
ssize_t rv = read(fd, buf, sizeof(buf));
|
||
|
|
close(fd);
|
||
|
|
if (g_vsyscall == 0) {
|
||
|
|
assert(rv == 0);
|
||
|
|
} else {
|
||
|
|
size_t len = strlen(g_proc_pid_maps_vsyscall);
|
||
|
|
/* TODO "ProtectionKey:" */
|
||
|
|
assert(rv > len);
|
||
|
|
assert(memcmp(buf, g_proc_pid_maps_vsyscall, len) == 0);
|
||
|
|
}
|
||
|
|
return EXIT_SUCCESS;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
static const char g_smaps_rollup[] =
|
||
|
|
"00000000-00000000 ---p 00000000 00:00 0 [rollup]\n"
|
||
|
|
"Rss: 0 kB\n"
|
||
|
|
"Pss: 0 kB\n"
|
||
|
|
"Pss_Dirty: 0 kB\n"
|
||
|
|
"Pss_Anon: 0 kB\n"
|
||
|
|
"Pss_File: 0 kB\n"
|
||
|
|
"Pss_Shmem: 0 kB\n"
|
||
|
|
"Shared_Clean: 0 kB\n"
|
||
|
|
"Shared_Dirty: 0 kB\n"
|
||
|
|
"Private_Clean: 0 kB\n"
|
||
|
|
"Private_Dirty: 0 kB\n"
|
||
|
|
"Referenced: 0 kB\n"
|
||
|
|
"Anonymous: 0 kB\n"
|
||
|
|
"LazyFree: 0 kB\n"
|
||
|
|
"AnonHugePages: 0 kB\n"
|
||
|
|
"ShmemPmdMapped: 0 kB\n"
|
||
|
|
"FilePmdMapped: 0 kB\n"
|
||
|
|
"Shared_Hugetlb: 0 kB\n"
|
||
|
|
"Private_Hugetlb: 0 kB\n"
|
||
|
|
"Swap: 0 kB\n"
|
||
|
|
"SwapPss: 0 kB\n"
|
||
|
|
"Locked: 0 kB\n"
|
||
|
|
;
|
||
|
|
|
||
|
|
static int test_proc_pid_smaps_rollup(pid_t pid)
|
||
|
|
{
|
||
|
|
char buf[4096];
|
||
|
|
snprintf(buf, sizeof(buf), "/proc/%u/smaps_rollup", pid);
|
||
|
|
int fd = open(buf, O_RDONLY);
|
||
|
|
if (fd == -1) {
|
||
|
|
if (errno == ENOENT) {
|
||
|
|
/*
|
||
|
|
* /proc/${pid}/smaps_rollup is under CONFIG_PROC_PAGE_MONITOR,
|
||
|
|
* it doesn't necessarily exist.
|
||
|
|
*/
|
||
|
|
return EXIT_SUCCESS;
|
||
|
|
}
|
||
|
|
perror("open /proc/${pid}/smaps_rollup");
|
||
|
|
return EXIT_FAILURE;
|
||
|
|
} else {
|
||
|
|
ssize_t rv = read(fd, buf, sizeof(buf));
|
||
|
|
close(fd);
|
||
|
|
assert(rv == sizeof(g_smaps_rollup) - 1);
|
||
|
|
assert(memcmp(buf, g_smaps_rollup, sizeof(g_smaps_rollup) - 1) == 0);
|
||
|
|
return EXIT_SUCCESS;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
int main(void)
|
||
|
|
{
|
||
|
|
int rv = EXIT_SUCCESS;
|
||
|
|
|
||
|
|
vsyscall();
|
||
|
|
|
||
|
|
switch (g_vsyscall) {
|
||
|
|
case 0:
|
||
|
|
g_proc_pid_maps_vsyscall = proc_pid_maps_vsyscall_0;
|
||
|
|
g_proc_pid_smaps_vsyscall = proc_pid_smaps_vsyscall_0;
|
||
|
|
break;
|
||
|
|
case 1:
|
||
|
|
g_proc_pid_maps_vsyscall = proc_pid_maps_vsyscall_1;
|
||
|
|
g_proc_pid_smaps_vsyscall = proc_pid_smaps_vsyscall_1;
|
||
|
|
break;
|
||
|
|
case 2:
|
||
|
|
g_proc_pid_maps_vsyscall = proc_pid_maps_vsyscall_2;
|
||
|
|
g_proc_pid_smaps_vsyscall = proc_pid_smaps_vsyscall_2;
|
||
|
|
break;
|
||
|
|
default:
|
||
|
|
abort();
|
||
|
|
}
|
||
|
|
|
||
|
|
pid_t pid = fork();
|
||
|
|
if (pid == -1) {
|
||
|
|
perror("fork");
|
||
|
|
return EXIT_FAILURE;
|
||
|
|
} else if (pid == 0) {
|
||
|
|
rv = ptrace(PTRACE_TRACEME, 0, NULL, NULL);
|
||
|
|
if (rv != 0) {
|
||
|
|
if (errno == EPERM) {
|
||
|
|
fprintf(stderr,
|
||
|
|
"Did you know? ptrace(PTRACE_TRACEME) doesn't work under strace.\n"
|
||
|
|
);
|
||
|
|
kill(getppid(), SIGTERM);
|
||
|
|
return EXIT_FAILURE;
|
||
|
|
}
|
||
|
|
perror("ptrace PTRACE_TRACEME");
|
||
|
|
return EXIT_FAILURE;
|
||
|
|
}
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Hide "segfault at ..." messages. Signal handler won't run.
|
||
|
|
*/
|
||
|
|
struct sigaction act = {};
|
||
|
|
act.sa_flags = SA_SIGINFO;
|
||
|
|
act.sa_sigaction = sigaction_SIGSEGV;
|
||
|
|
sigaction(SIGSEGV, &act, NULL);
|
||
|
|
|
||
|
|
#ifdef __amd64__
|
||
|
|
munmap(NULL, ((size_t)1 << 47) - 4096);
|
||
|
|
#else
|
||
|
|
#error "implement 'unmap everything'"
|
||
|
|
#endif
|
||
|
|
return EXIT_FAILURE;
|
||
|
|
} else {
|
||
|
|
/*
|
||
|
|
* TODO find reliable way to signal parent that munmap(2) completed.
|
||
|
|
* Child can't do it directly because it effectively doesn't exist
|
||
|
|
* anymore. Looking at child's VM files isn't 100% reliable either:
|
||
|
|
* due to a bug they may not become empty or empty-like.
|
||
|
|
*/
|
||
|
|
sleep(1);
|
||
|
|
|
||
|
|
if (rv == EXIT_SUCCESS) {
|
||
|
|
rv = test_proc_pid_maps(pid);
|
||
|
|
}
|
||
|
|
if (rv == EXIT_SUCCESS) {
|
||
|
|
rv = test_proc_pid_numa_maps(pid);
|
||
|
|
}
|
||
|
|
if (rv == EXIT_SUCCESS) {
|
||
|
|
rv = test_proc_pid_smaps(pid);
|
||
|
|
}
|
||
|
|
if (rv == EXIT_SUCCESS) {
|
||
|
|
rv = test_proc_pid_smaps_rollup(pid);
|
||
|
|
}
|
||
|
|
/*
|
||
|
|
* TODO test /proc/${pid}/statm, task_statm()
|
||
|
|
* ->start_code, ->end_code aren't updated by munmap().
|
||
|
|
* Output can be "0 0 0 2 0 0 0\n" where "2" can be anything.
|
||
|
|
*/
|
||
|
|
|
||
|
|
/* Cut the rope. */
|
||
|
|
int wstatus;
|
||
|
|
waitpid(pid, &wstatus, 0);
|
||
|
|
assert(WIFSTOPPED(wstatus));
|
||
|
|
assert(WSTOPSIG(wstatus) == SIGSEGV);
|
||
|
|
}
|
||
|
|
|
||
|
|
return rv;
|
||
|
|
}
|