/*
* Copyright (c) 2019 Alexey Dobriyan <[email protected]>
*
* 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.
*/
/*
* Fork and exec tiny 1 page executable which precisely controls its VM.
* Test /proc/$PID/maps
* Test /proc/$PID/smaps
* Test /proc/$PID/smaps_rollup
* Test /proc/$PID/statm
*
* FIXME require CONFIG_TMPFS which can be disabled
* FIXME test other values from "smaps"
* FIXME support other archs
*/
#undef NDEBUG
#include <assert.h>
#include <errno.h>
#include <sched.h>
#include <signal.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sys/mount.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/syscall.h>
#include <sys/uio.h>
#include <linux/kdev_t.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <linux/fs.h>
#include "../kselftest.h"
static inline long sys_execveat(int dirfd, const char *pathname, char **argv, char **envp, int flags)
{
return syscall(SYS_execveat, dirfd, pathname, argv, envp, flags);
}
static void make_private_tmp(void)
{
if (unshare(CLONE_NEWNS) == -1) {
if (errno == ENOSYS || errno == EPERM) {
exit(4);
}
exit(1);
}
if (mount(NULL, "/", NULL, MS_PRIVATE|MS_REC, NULL) == -1) {
exit(1);
}
if (mount(NULL, "/tmp", "tmpfs", 0, NULL) == -1) {
exit(1);
}
}
static pid_t pid = -1;
static void ate(void)
{
if (pid > 0) {
kill(pid, SIGTERM);
}
}
struct elf64_hdr {
uint8_t e_ident[16];
uint16_t e_type;
uint16_t e_machine;
uint32_t e_version;
uint64_t e_entry;
uint64_t e_phoff;
uint64_t e_shoff;
uint32_t e_flags;
uint16_t e_ehsize;
uint16_t e_phentsize;
uint16_t e_phnum;
uint16_t e_shentsize;
uint16_t e_shnum;
uint16_t e_shstrndx;
};
struct elf64_phdr {
uint32_t p_type;
uint32_t p_flags;
uint64_t p_offset;
uint64_t p_vaddr;
uint64_t p_paddr;
uint64_t p_filesz;
uint64_t p_memsz;
uint64_t p_align;
};
#ifdef __x86_64__
#define PAGE_SIZE 4096
#define VADDR (1UL << 32)
#define MAPS_OFFSET 73
#define syscall 0x0f, 0x05
#define mov_rdi(x) \
0x48, 0xbf, \
(x)&0xff, ((x)>>8)&0xff, ((x)>>16)&0xff, ((x)>>24)&0xff, \
((x)>>32)&0xff, ((x)>>40)&0xff, ((x)>>48)&0xff, ((x)>>56)&0xff
#define mov_rsi(x) \
0x48, 0xbe, \
(x)&0xff, ((x)>>8)&0xff, ((x)>>16)&0xff, ((x)>>24)&0xff, \
((x)>>32)&0xff, ((x)>>40)&0xff, ((x)>>48)&0xff, ((x)>>56)&0xff
#define mov_eax(x) \
0xb8, (x)&0xff, ((x)>>8)&0xff, ((x)>>16)&0xff, ((x)>>24)&0xff
static const uint8_t payload[] = {
/* Casually unmap stack, vDSO and everything else. */
/* munmap */
mov_rdi(VADDR + 4096),
mov_rsi((1ULL << 47) - 4096 - VADDR - 4096),
mov_eax(11),
syscall,
/* Ping parent. */
/* write(0, &c, 1); */
0x31, 0xff, /* xor edi, edi */
0x48, 0x8d, 0x35, 0x00, 0x00, 0x00, 0x00, /* lea rsi, [rip] */
0xba, 0x01, 0x00, 0x00, 0x00, /* mov edx, 1 */
mov_eax(1),
syscall,
/* 1: pause(); */
mov_eax(34),
syscall,
0xeb, 0xf7, /* jmp 1b */
};
static int make_exe(const uint8_t *payload, size_t len)
{
struct elf64_hdr h;
struct elf64_phdr ph;
struct iovec iov[3] = {
{&h, sizeof(struct elf64_hdr)},
{&ph, sizeof(struct elf64_phdr)},
{(void *)payload, len},
};
int fd, fd1;
char buf[64];
memset(&h, 0, sizeof(h));
h.e_ident[0] = 0x7f;
h.e_ident[1] = 'E';
h.e_ident[2] = 'L';
h.e_ident[3] = 'F';
h.e_ident[4] = 2;
h.e_ident[5] = 1;
h.e_ident[6] = 1;
h.e_ident[7] = 0;
h.e_type = 2;
h.e_machine = 0x3e;
h.e_version = 1;
h.e_entry = VADDR + sizeof(struct elf64_hdr) + sizeof(struct elf64_phdr);
h.e_phoff = sizeof(struct elf64_hdr);
h.e_shoff = 0;
h.e_flags = 0;
h.e_ehsize = sizeof(struct elf64_hdr);
h.e_phentsize = sizeof(struct elf64_phdr);
h.e_phnum = 1;
h.e_shentsize = 0;
h.e_shnum = 0;
h.e_shstrndx = 0;
memset(&ph, 0, sizeof(ph));
ph.p_type = 1;
ph.p_flags = (1<<2)|1;
ph.p_offset = 0;
ph.p_vaddr = VADDR;
ph.p_paddr = 0;
ph.p_filesz = sizeof(struct elf64_hdr) + sizeof(struct elf64_phdr) + len;
ph.p_memsz = sizeof(struct elf64_hdr) + sizeof(struct elf64_phdr) + len;
ph.p_align = 4096;
fd = openat(AT_FDCWD, "/tmp", O_WRONLY|O_EXCL|O_TMPFILE, 0700);
if (fd == -1) {
exit(1);
}
if (writev(fd, iov, 3) != sizeof(struct elf64_hdr) + sizeof(struct elf64_phdr) + len) {
exit(1);
}
/* Avoid ETXTBSY on exec. */
snprintf(buf, sizeof(buf), "/proc/self/fd/%u", fd);
fd1 = open(buf, O_RDONLY|O_CLOEXEC);
close(fd);
return fd1;
}
#endif
/*
* 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 *str_vsyscall;
static const char str_vsyscall_0[] = "";
static const char str_vsyscall_1[] =
"ffffffffff600000-ffffffffff601000 --xp 00000000 00:00 0 [vsyscall]\n";
static const char str_vsyscall_2[] =
"ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0 [vsyscall]\n";
#ifdef __x86_64__
static void sigaction_SIGSEGV(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) {
struct rlimit rlim = {0, 0};
(void)setrlimit(RLIMIT_CORE, &rlim);
/* Hide "segfault at ffffffffff600000" messages. */
struct sigaction act;
memset(&act, 0, sizeof(struct sigaction));
act.sa_flags = SA_SIGINFO;
act.sa_sigaction = sigaction_SIGSEGV;
(void)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: wstatus %08x\n", wstatus);
exit(1);
}
}
int main(void)
{
int pipefd[2];
int exec_fd;
vsyscall();
switch (g_vsyscall) {
case 0:
str_vsyscall = str_vsyscall_0;
break;
case 1:
str_vsyscall = str_vsyscall_1;
break;
case 2:
str_vsyscall = str_vsyscall_2;
break;
default:
abort();
}
atexit(ate);
make_private_tmp();
/* Reserve fd 0 for 1-byte pipe ping from child. */
close(0);
if (open("/", O_RDONLY|O_DIRECTORY|O_PATH) != 0) {
return 1;
}
exec_fd = make_exe(payload, sizeof(payload));
if (pipe(pipefd) == -1) {
return 1;
}
if (dup2(pipefd[1], 0) != 0) {
return 1;
}
pid = fork();
if (pid == -1) {
return 1;
}
if (pid == 0) {
sys_execveat(exec_fd, "", NULL, NULL, AT_EMPTY_PATH);
return 1;
}
char _;
if (read(pipefd[0], &_, 1) != 1) {
return 1;
}
struct stat st;
if (fstat(exec_fd, &st) == -1) {
return 1;
}
/* Generate "head -n1 /proc/$PID/maps" */
char buf0[256];
memset(buf0, ' ', sizeof(buf0));
int len = snprintf(buf0, sizeof(buf0),
"%08lx-%08lx r-xp 00000000 %02lx:%02lx %llu",
VADDR, VADDR + PAGE_SIZE,
MAJOR(st.st_dev), MINOR(st.st_dev),
(unsigned long long)st.st_ino);
buf0[len] = ' ';
snprintf(buf0 + MAPS_OFFSET, sizeof(buf0) - MAPS_OFFSET,
"/tmp/#%llu (deleted)\n", (unsigned long long)st.st_ino);
/* Test /proc/$PID/maps */
{
const size_t len = strlen(buf0) + strlen(str_vsyscall);
char buf[256];
ssize_t rv;
int fd;
snprintf(buf, sizeof(buf), "/proc/%u/maps", pid);
fd = open(buf, O_RDONLY);
if (fd == -1) {
return 1;
}
rv = read(fd, buf, sizeof(buf));
assert(rv == len);
assert(memcmp(buf, buf0, strlen(buf0)) == 0);
if (g_vsyscall > 0) {
assert(memcmp(buf + strlen(buf0), str_vsyscall, strlen(str_vsyscall)) == 0);
}
}
/* Test /proc/$PID/smaps */
{
char buf[4096];
ssize_t rv;
int fd;
snprintf(buf, sizeof(buf), "/proc/%u/smaps", pid);
fd = open(buf, O_RDONLY);
if (fd == -1) {
return 1;
}
rv = read(fd, buf, sizeof(buf));
assert(0 <= rv && rv <= sizeof(buf));
assert(rv >= strlen(buf0));
assert(memcmp(buf, buf0, strlen(buf0)) == 0);
#define RSS1 "Rss: 4 kB\n"
#define RSS2 "Rss: 0 kB\n"
#define PSS1 "Pss: 4 kB\n"
#define PSS2 "Pss: 0 kB\n"
assert(memmem(buf, rv, RSS1, strlen(RSS1)) ||
memmem(buf, rv, RSS2, strlen(RSS2)));
assert(memmem(buf, rv, PSS1, strlen(PSS1)) ||
memmem(buf, rv, PSS2, strlen(PSS2)));
static const char *S[] = {
"Size: 4 kB\n",
"KernelPageSize: 4 kB\n",
"MMUPageSize: 4 kB\n",
"Anonymous: 0 kB\n",
"AnonHugePages: 0 kB\n",
"Shared_Hugetlb: 0 kB\n",
"Private_Hugetlb: 0 kB\n",
"Locked: 0 kB\n",
};
int i;
for (i = 0; i < ARRAY_SIZE(S); i++) {
assert(memmem(buf, rv, S[i], strlen(S[i])));
}
if (g_vsyscall > 0) {
assert(memmem(buf, rv, str_vsyscall, strlen(str_vsyscall)));
}
}
/* Test /proc/$PID/smaps_rollup */
{
char bufr[256];
memset(bufr, ' ', sizeof(bufr));
len = snprintf(bufr, sizeof(bufr),
"%08lx-%08lx ---p 00000000 00:00 0",
VADDR, VADDR + PAGE_SIZE);
bufr[len] = ' ';
snprintf(bufr + MAPS_OFFSET, sizeof(bufr) - MAPS_OFFSET,
"[rollup]\n");
char buf[1024];
ssize_t rv;
int fd;
snprintf(buf, sizeof(buf), "/proc/%u/smaps_rollup", pid);
fd = open(buf, O_RDONLY);
if (fd == -1) {
return 1;
}
rv = read(fd, buf, sizeof(buf));
assert(0 <= rv && rv <= sizeof(buf));
assert(rv >= strlen(bufr));
assert(memcmp(buf, bufr, strlen(bufr)) == 0);
assert(memmem(buf, rv, RSS1, strlen(RSS1)) ||
memmem(buf, rv, RSS2, strlen(RSS2)));
assert(memmem(buf, rv, PSS1, strlen(PSS1)) ||
memmem(buf, rv, PSS2, strlen(PSS2)));
static const char *S[] = {
"Anonymous: 0 kB\n",
"AnonHugePages: 0 kB\n",
"Shared_Hugetlb: 0 kB\n",
"Private_Hugetlb: 0 kB\n",
"Locked: 0 kB\n",
};
int i;
for (i = 0; i < ARRAY_SIZE(S); i++) {
assert(memmem(buf, rv, S[i], strlen(S[i])));
}
}
/* Test /proc/$PID/statm */
{
char buf[64];
ssize_t rv;
int fd;
snprintf(buf, sizeof(buf), "/proc/%u/statm", pid);
fd = open(buf, O_RDONLY);
if (fd == -1) {
return 1;
}
rv = read(fd, buf, sizeof(buf));
assert(rv == 7 * 2);
assert(buf[0] == '1'); /* ->total_vm */
assert(buf[1] == ' ');
assert(buf[2] == '0' || buf[2] == '1'); /* rss */
assert(buf[3] == ' ');
assert(buf[4] == '0' || buf[2] == '1'); /* file rss */
assert(buf[5] == ' ');
assert(buf[6] == '1'); /* ELF executable segments */
assert(buf[7] == ' ');
assert(buf[8] == '0');
assert(buf[9] == ' ');
assert(buf[10] == '0'); /* ->data_vm + ->stack_vm */
assert(buf[11] == ' ');
assert(buf[12] == '0');
assert(buf[13] == '\n');
}
/* Test PROCMAP_QUERY ioctl() for /proc/$PID/maps */
{
char path_buf[256], exp_path_buf[256];
struct procmap_query q;
int fd, err;
snprintf(path_buf, sizeof(path_buf), "/proc/%u/maps", pid);
fd = open(path_buf, O_RDONLY);
if (fd == -1)
return 1;
/* CASE 1: exact MATCH at VADDR */
memset(&q, 0, sizeof(q));
q.size = sizeof(q);
q.query_addr = VADDR;
q.query_flags = 0;
q.vma_name_addr = (__u64)(unsigned long)path_buf;
q.vma_name_size = sizeof(path_buf);
err = ioctl(fd, PROCMAP_QUERY, &q);
assert(err == 0);
assert(q.query_addr == VADDR);
assert(q.query_flags == 0);
assert(q.vma_flags == (PROCMAP_QUERY_VMA_READABLE | PROCMAP_QUERY_VMA_EXECUTABLE));
assert(q.vma_start == VADDR);
assert(q.vma_end == VADDR + PAGE_SIZE);
assert(q.vma_page_size == PAGE_SIZE);
assert(q.vma_offset == 0);
assert(q.inode == st.st_ino);
assert(q.dev_major == MAJOR(st.st_dev));
assert(q.dev_minor == MINOR(st.st_dev));
snprintf(exp_path_buf, sizeof(exp_path_buf),
"/tmp/#%llu (deleted)", (unsigned long long)st.st_ino);
assert(q.vma_name_size == strlen(exp_path_buf) + 1);
assert(strcmp(path_buf, exp_path_buf) == 0);
/* CASE 2: NO MATCH at VADDR-1 */
memset(&q, 0, sizeof(q));
q.size = sizeof(q);
q.query_addr = VADDR - 1;
q.query_flags = 0; /* exact match */
err = ioctl(fd, PROCMAP_QUERY, &q);
err = err < 0 ? -errno : 0;
assert(err == -ENOENT);
/* CASE 3: MATCH COVERING_OR_NEXT_VMA at VADDR - 1 */
memset(&q, 0, sizeof(q));
q.size = sizeof(q);
q.query_addr = VADDR - 1;
q.query_flags = PROCMAP_QUERY_COVERING_OR_NEXT_VMA;
err = ioctl(fd, PROCMAP_QUERY, &q);
assert(err == 0);
assert(q.query_addr == VADDR - 1);
assert(q.query_flags == PROCMAP_QUERY_COVERING_OR_NEXT_VMA);
assert(q.vma_start == VADDR);
assert(q.vma_end == VADDR + PAGE_SIZE);
/* CASE 4: NO MATCH at VADDR + PAGE_SIZE */
memset(&q, 0, sizeof(q));
q.size = sizeof(q);
q.query_addr = VADDR + PAGE_SIZE; /* point right after the VMA */
q.query_flags = PROCMAP_QUERY_COVERING_OR_NEXT_VMA;
err = ioctl(fd, PROCMAP_QUERY, &q);
err = err < 0 ? -errno : 0;
assert(err == -ENOENT);
/* CASE 5: NO MATCH WRITABLE at VADDR */
memset(&q, 0, sizeof(q));
q.size = sizeof(q);
q.query_addr = VADDR;
q.query_flags = PROCMAP_QUERY_VMA_WRITABLE;
err = ioctl(fd, PROCMAP_QUERY, &q);
err = err < 0 ? -errno : 0;
assert(err == -ENOENT);
}
return 0;
}
#else
int main(void)
{
return 4;
}
#endif
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