2 * Copyright (c) 2019 Alexey Dobriyan <adobriyan@gmail.com>
4 * Permission to use, copy, modify, and distribute this software for any
5 * purpose with or without fee is hereby granted, provided that the above
6 * copyright notice and this permission notice appear in all copies.
8 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 * Fork and exec tiny 1 page executable which precisely controls its VM.
18 * Test /proc/$PID/maps
19 * Test /proc/$PID/smaps
20 * Test /proc/$PID/smaps_rollup
21 * Test /proc/$PID/statm
23 * FIXME require CONFIG_TMPFS which can be disabled
24 * FIXME test other values from "smaps"
25 * FIXME support other archs
37 #include <sys/mount.h>
38 #include <sys/types.h>
43 #include <sys/syscall.h>
45 #include <linux/kdev_t.h>
47 #include <sys/resource.h>
49 #include "../kselftest.h"
51 static inline long sys_execveat(int dirfd, const char *pathname, char **argv, char **envp, int flags)
53 return syscall(SYS_execveat, dirfd, pathname, argv, envp, flags);
56 static void make_private_tmp(void)
58 if (unshare(CLONE_NEWNS) == -1) {
59 if (errno == ENOSYS || errno == EPERM) {
64 if (mount(NULL, "/", NULL, MS_PRIVATE|MS_REC, NULL) == -1) {
67 if (mount(NULL, "/tmp", "tmpfs", 0, NULL) == -1) {
72 static pid_t pid = -1;
109 #define PAGE_SIZE 4096
110 #define VADDR (1UL << 32)
111 #define MAPS_OFFSET 73
113 #define syscall 0x0f, 0x05
116 (x)&0xff, ((x)>>8)&0xff, ((x)>>16)&0xff, ((x)>>24)&0xff, \
117 ((x)>>32)&0xff, ((x)>>40)&0xff, ((x)>>48)&0xff, ((x)>>56)&0xff
121 (x)&0xff, ((x)>>8)&0xff, ((x)>>16)&0xff, ((x)>>24)&0xff, \
122 ((x)>>32)&0xff, ((x)>>40)&0xff, ((x)>>48)&0xff, ((x)>>56)&0xff
125 0xb8, (x)&0xff, ((x)>>8)&0xff, ((x)>>16)&0xff, ((x)>>24)&0xff
127 static const uint8_t payload[] = {
128 /* Casually unmap stack, vDSO and everything else. */
130 mov_rdi(VADDR + 4096),
131 mov_rsi((1ULL << 47) - 4096 - VADDR - 4096),
136 /* write(0, &c, 1); */
137 0x31, 0xff, /* xor edi, edi */
138 0x48, 0x8d, 0x35, 0x00, 0x00, 0x00, 0x00, /* lea rsi, [rip] */
139 0xba, 0x01, 0x00, 0x00, 0x00, /* mov edx, 1 */
147 0xeb, 0xf7, /* jmp 1b */
150 static int make_exe(const uint8_t *payload, size_t len)
153 struct elf64_phdr ph;
155 struct iovec iov[3] = {
156 {&h, sizeof(struct elf64_hdr)},
157 {&ph, sizeof(struct elf64_phdr)},
158 {(void *)payload, len},
163 memset(&h, 0, sizeof(h));
175 h.e_entry = VADDR + sizeof(struct elf64_hdr) + sizeof(struct elf64_phdr);
176 h.e_phoff = sizeof(struct elf64_hdr);
179 h.e_ehsize = sizeof(struct elf64_hdr);
180 h.e_phentsize = sizeof(struct elf64_phdr);
186 memset(&ph, 0, sizeof(ph));
188 ph.p_flags = (1<<2)|1;
192 ph.p_filesz = sizeof(struct elf64_hdr) + sizeof(struct elf64_phdr) + len;
193 ph.p_memsz = sizeof(struct elf64_hdr) + sizeof(struct elf64_phdr) + len;
196 fd = openat(AT_FDCWD, "/tmp", O_WRONLY|O_EXCL|O_TMPFILE, 0700);
201 if (writev(fd, iov, 3) != sizeof(struct elf64_hdr) + sizeof(struct elf64_phdr) + len) {
205 /* Avoid ETXTBSY on exec. */
206 snprintf(buf, sizeof(buf), "/proc/self/fd/%u", fd);
207 fd1 = open(buf, O_RDONLY|O_CLOEXEC);
214 static bool g_vsyscall = false;
216 static const char str_vsyscall[] =
217 "ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0 [vsyscall]\n";
220 static void sigaction_SIGSEGV(int _, siginfo_t *__, void *___)
226 * vsyscall page can't be unmapped, probe it with memory load.
228 static void vsyscall(void)
235 fprintf(stderr, "fork, errno %d\n", errno);
239 struct rlimit rlim = {0, 0};
240 (void)setrlimit(RLIMIT_CORE, &rlim);
242 /* Hide "segfault at ffffffffff600000" messages. */
243 struct sigaction act;
244 memset(&act, 0, sizeof(struct sigaction));
245 act.sa_flags = SA_SIGINFO;
246 act.sa_sigaction = sigaction_SIGSEGV;
247 (void)sigaction(SIGSEGV, &act, NULL);
249 *(volatile int *)0xffffffffff600000UL;
252 waitpid(pid, &wstatus, 0);
253 if (WIFEXITED(wstatus) && WEXITSTATUS(wstatus) == 0) {
269 /* Reserve fd 0 for 1-byte pipe ping from child. */
271 if (open("/", O_RDONLY|O_DIRECTORY|O_PATH) != 0) {
275 exec_fd = make_exe(payload, sizeof(payload));
277 if (pipe(pipefd) == -1) {
280 if (dup2(pipefd[1], 0) != 0) {
289 sys_execveat(exec_fd, "", NULL, NULL, AT_EMPTY_PATH);
294 if (read(pipefd[0], &_, 1) != 1) {
299 if (fstat(exec_fd, &st) == -1) {
303 /* Generate "head -n1 /proc/$PID/maps" */
305 memset(buf0, ' ', sizeof(buf0));
306 int len = snprintf(buf0, sizeof(buf0),
307 "%08lx-%08lx r-xp 00000000 %02lx:%02lx %llu",
308 VADDR, VADDR + PAGE_SIZE,
309 MAJOR(st.st_dev), MINOR(st.st_dev),
310 (unsigned long long)st.st_ino);
312 snprintf(buf0 + MAPS_OFFSET, sizeof(buf0) - MAPS_OFFSET,
313 "/tmp/#%llu (deleted)\n", (unsigned long long)st.st_ino);
315 /* Test /proc/$PID/maps */
317 const size_t len = strlen(buf0) + (g_vsyscall ? strlen(str_vsyscall) : 0);
322 snprintf(buf, sizeof(buf), "/proc/%u/maps", pid);
323 fd = open(buf, O_RDONLY);
327 rv = read(fd, buf, sizeof(buf));
329 assert(memcmp(buf, buf0, strlen(buf0)) == 0);
331 assert(memcmp(buf + strlen(buf0), str_vsyscall, strlen(str_vsyscall)) == 0);
335 /* Test /proc/$PID/smaps */
341 snprintf(buf, sizeof(buf), "/proc/%u/smaps", pid);
342 fd = open(buf, O_RDONLY);
346 rv = read(fd, buf, sizeof(buf));
347 assert(0 <= rv && rv <= sizeof(buf));
349 assert(rv >= strlen(buf0));
350 assert(memcmp(buf, buf0, strlen(buf0)) == 0);
352 #define RSS1 "Rss: 4 kB\n"
353 #define RSS2 "Rss: 0 kB\n"
354 #define PSS1 "Pss: 4 kB\n"
355 #define PSS2 "Pss: 0 kB\n"
356 assert(memmem(buf, rv, RSS1, strlen(RSS1)) ||
357 memmem(buf, rv, RSS2, strlen(RSS2)));
358 assert(memmem(buf, rv, PSS1, strlen(PSS1)) ||
359 memmem(buf, rv, PSS2, strlen(PSS2)));
361 static const char *S[] = {
363 "KernelPageSize: 4 kB\n",
364 "MMUPageSize: 4 kB\n",
366 "AnonHugePages: 0 kB\n",
367 "Shared_Hugetlb: 0 kB\n",
368 "Private_Hugetlb: 0 kB\n",
373 for (i = 0; i < ARRAY_SIZE(S); i++) {
374 assert(memmem(buf, rv, S[i], strlen(S[i])));
378 assert(memmem(buf, rv, str_vsyscall, strlen(str_vsyscall)));
382 /* Test /proc/$PID/smaps_rollup */
385 memset(bufr, ' ', sizeof(bufr));
386 len = snprintf(bufr, sizeof(bufr),
387 "%08lx-%08lx ---p 00000000 00:00 0",
388 VADDR, VADDR + PAGE_SIZE);
390 snprintf(bufr + MAPS_OFFSET, sizeof(bufr) - MAPS_OFFSET,
397 snprintf(buf, sizeof(buf), "/proc/%u/smaps_rollup", pid);
398 fd = open(buf, O_RDONLY);
402 rv = read(fd, buf, sizeof(buf));
403 assert(0 <= rv && rv <= sizeof(buf));
405 assert(rv >= strlen(bufr));
406 assert(memcmp(buf, bufr, strlen(bufr)) == 0);
408 assert(memmem(buf, rv, RSS1, strlen(RSS1)) ||
409 memmem(buf, rv, RSS2, strlen(RSS2)));
410 assert(memmem(buf, rv, PSS1, strlen(PSS1)) ||
411 memmem(buf, rv, PSS2, strlen(PSS2)));
413 static const char *S[] = {
415 "AnonHugePages: 0 kB\n",
416 "Shared_Hugetlb: 0 kB\n",
417 "Private_Hugetlb: 0 kB\n",
422 for (i = 0; i < ARRAY_SIZE(S); i++) {
423 assert(memmem(buf, rv, S[i], strlen(S[i])));
427 /* Test /proc/$PID/statm */
433 snprintf(buf, sizeof(buf), "/proc/%u/statm", pid);
434 fd = open(buf, O_RDONLY);
438 rv = read(fd, buf, sizeof(buf));
441 assert(buf[0] == '1'); /* ->total_vm */
442 assert(buf[1] == ' ');
443 assert(buf[2] == '0' || buf[2] == '1'); /* rss */
444 assert(buf[3] == ' ');
445 assert(buf[4] == '0' || buf[2] == '1'); /* file rss */
446 assert(buf[5] == ' ');
447 assert(buf[6] == '1'); /* ELF executable segments */
448 assert(buf[7] == ' ');
449 assert(buf[8] == '0');
450 assert(buf[9] == ' ');
451 assert(buf[10] == '0'); /* ->data_vm + ->stack_vm */
452 assert(buf[11] == ' ');
453 assert(buf[12] == '0');
454 assert(buf[13] == '\n');