1 /*
2 * Copyright (c) 2019 Alexey Dobriyan <adobriyan@gmail.com>
3 *
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.
7 *
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.
15 */
16 /*
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
22 *
23 * FIXME require CONFIG_TMPFS which can be disabled
24 * FIXME test other values from "smaps"
25 * FIXME support other archs
26 */
27 #undef NDEBUG
28 #include <assert.h>
29 #include <errno.h>
30 #include <sched.h>
31 #include <signal.h>
32 #include <stdbool.h>
33 #include <stdint.h>
34 #include <stdio.h>
35 #include <string.h>
36 #include <stdlib.h>
37 #include <sys/mount.h>
38 #include <sys/types.h>
39 #include <sys/stat.h>
40 #include <sys/wait.h>
41 #include <fcntl.h>
42 #include <unistd.h>
43 #include <sys/syscall.h>
44 #include <sys/uio.h>
45 #include <linux/kdev_t.h>
46 #include <sys/time.h>
47 #include <sys/resource.h>
48
49 #include "../kselftest.h"
50
sys_execveat(int dirfd,const char * pathname,char ** argv,char ** envp,int flags)51 static inline long sys_execveat(int dirfd, const char *pathname, char **argv, char **envp, int flags)
52 {
53 return syscall(SYS_execveat, dirfd, pathname, argv, envp, flags);
54 }
55
make_private_tmp(void)56 static void make_private_tmp(void)
57 {
58 if (unshare(CLONE_NEWNS) == -1) {
59 if (errno == ENOSYS || errno == EPERM) {
60 exit(4);
61 }
62 exit(1);
63 }
64 if (mount(NULL, "/", NULL, MS_PRIVATE|MS_REC, NULL) == -1) {
65 exit(1);
66 }
67 if (mount(NULL, "/tmp", "tmpfs", 0, NULL) == -1) {
68 exit(1);
69 }
70 }
71
72 static pid_t pid = -1;
ate(void)73 static void ate(void)
74 {
75 if (pid > 0) {
76 kill(pid, SIGTERM);
77 }
78 }
79
80 struct elf64_hdr {
81 uint8_t e_ident[16];
82 uint16_t e_type;
83 uint16_t e_machine;
84 uint32_t e_version;
85 uint64_t e_entry;
86 uint64_t e_phoff;
87 uint64_t e_shoff;
88 uint32_t e_flags;
89 uint16_t e_ehsize;
90 uint16_t e_phentsize;
91 uint16_t e_phnum;
92 uint16_t e_shentsize;
93 uint16_t e_shnum;
94 uint16_t e_shstrndx;
95 };
96
97 struct elf64_phdr {
98 uint32_t p_type;
99 uint32_t p_flags;
100 uint64_t p_offset;
101 uint64_t p_vaddr;
102 uint64_t p_paddr;
103 uint64_t p_filesz;
104 uint64_t p_memsz;
105 uint64_t p_align;
106 };
107
108 #ifdef __x86_64__
109 #define PAGE_SIZE 4096
110 #define VADDR (1UL << 32)
111 #define MAPS_OFFSET 73
112
113 #define syscall 0x0f, 0x05
114 #define mov_rdi(x) \
115 0x48, 0xbf, \
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
118
119 #define mov_rsi(x) \
120 0x48, 0xbe, \
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
123
124 #define mov_eax(x) \
125 0xb8, (x)&0xff, ((x)>>8)&0xff, ((x)>>16)&0xff, ((x)>>24)&0xff
126
127 static const uint8_t payload[] = {
128 /* Casually unmap stack, vDSO and everything else. */
129 /* munmap */
130 mov_rdi(VADDR + 4096),
131 mov_rsi((1ULL << 47) - 4096 - VADDR - 4096),
132 mov_eax(11),
133 syscall,
134
135 /* Ping parent. */
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 */
140 mov_eax(1),
141 syscall,
142
143 /* 1: pause(); */
144 mov_eax(34),
145 syscall,
146
147 0xeb, 0xf7, /* jmp 1b */
148 };
149
make_exe(const uint8_t * payload,size_t len)150 static int make_exe(const uint8_t *payload, size_t len)
151 {
152 struct elf64_hdr h;
153 struct elf64_phdr ph;
154
155 struct iovec iov[3] = {
156 {&h, sizeof(struct elf64_hdr)},
157 {&ph, sizeof(struct elf64_phdr)},
158 {(void *)payload, len},
159 };
160 int fd, fd1;
161 char buf[64];
162
163 memset(&h, 0, sizeof(h));
164 h.e_ident[0] = 0x7f;
165 h.e_ident[1] = 'E';
166 h.e_ident[2] = 'L';
167 h.e_ident[3] = 'F';
168 h.e_ident[4] = 2;
169 h.e_ident[5] = 1;
170 h.e_ident[6] = 1;
171 h.e_ident[7] = 0;
172 h.e_type = 2;
173 h.e_machine = 0x3e;
174 h.e_version = 1;
175 h.e_entry = VADDR + sizeof(struct elf64_hdr) + sizeof(struct elf64_phdr);
176 h.e_phoff = sizeof(struct elf64_hdr);
177 h.e_shoff = 0;
178 h.e_flags = 0;
179 h.e_ehsize = sizeof(struct elf64_hdr);
180 h.e_phentsize = sizeof(struct elf64_phdr);
181 h.e_phnum = 1;
182 h.e_shentsize = 0;
183 h.e_shnum = 0;
184 h.e_shstrndx = 0;
185
186 memset(&ph, 0, sizeof(ph));
187 ph.p_type = 1;
188 ph.p_flags = (1<<2)|1;
189 ph.p_offset = 0;
190 ph.p_vaddr = VADDR;
191 ph.p_paddr = 0;
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;
194 ph.p_align = 4096;
195
196 fd = openat(AT_FDCWD, "/tmp", O_WRONLY|O_EXCL|O_TMPFILE, 0700);
197 if (fd == -1) {
198 exit(1);
199 }
200
201 if (writev(fd, iov, 3) != sizeof(struct elf64_hdr) + sizeof(struct elf64_phdr) + len) {
202 exit(1);
203 }
204
205 /* Avoid ETXTBSY on exec. */
206 snprintf(buf, sizeof(buf), "/proc/self/fd/%u", fd);
207 fd1 = open(buf, O_RDONLY|O_CLOEXEC);
208 close(fd);
209
210 return fd1;
211 }
212 #endif
213
214 static bool g_vsyscall = false;
215
216 static const char str_vsyscall[] =
217 "ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0 [vsyscall]\n";
218
219 #ifdef __x86_64__
sigaction_SIGSEGV(int _,siginfo_t * __,void * ___)220 static void sigaction_SIGSEGV(int _, siginfo_t *__, void *___)
221 {
222 _exit(1);
223 }
224
225 /*
226 * vsyscall page can't be unmapped, probe it with memory load.
227 */
vsyscall(void)228 static void vsyscall(void)
229 {
230 pid_t pid;
231 int wstatus;
232
233 pid = fork();
234 if (pid < 0) {
235 fprintf(stderr, "fork, errno %d\n", errno);
236 exit(1);
237 }
238 if (pid == 0) {
239 struct rlimit rlim = {0, 0};
240 (void)setrlimit(RLIMIT_CORE, &rlim);
241
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);
248
249 *(volatile int *)0xffffffffff600000UL;
250 exit(0);
251 }
252 waitpid(pid, &wstatus, 0);
253 if (WIFEXITED(wstatus) && WEXITSTATUS(wstatus) == 0) {
254 g_vsyscall = true;
255 }
256 }
257
main(void)258 int main(void)
259 {
260 int pipefd[2];
261 int exec_fd;
262
263 vsyscall();
264
265 atexit(ate);
266
267 make_private_tmp();
268
269 /* Reserve fd 0 for 1-byte pipe ping from child. */
270 close(0);
271 if (open("/", O_RDONLY|O_DIRECTORY|O_PATH) != 0) {
272 return 1;
273 }
274
275 exec_fd = make_exe(payload, sizeof(payload));
276
277 if (pipe(pipefd) == -1) {
278 return 1;
279 }
280 if (dup2(pipefd[1], 0) != 0) {
281 return 1;
282 }
283
284 pid = fork();
285 if (pid == -1) {
286 return 1;
287 }
288 if (pid == 0) {
289 sys_execveat(exec_fd, "", NULL, NULL, AT_EMPTY_PATH);
290 return 1;
291 }
292
293 char _;
294 if (read(pipefd[0], &_, 1) != 1) {
295 return 1;
296 }
297
298 struct stat st;
299 if (fstat(exec_fd, &st) == -1) {
300 return 1;
301 }
302
303 /* Generate "head -n1 /proc/$PID/maps" */
304 char buf0[256];
305 memset(buf0, ' ', sizeof(buf0));
306 int len = snprintf(buf0, sizeof(buf0),
307 "%08lx-%08lx r-xp 00000000 %02lx:%02lx %llu",
308 VADDR, VADDR + PAGE_SIZE,
309 MAJOR(st.st_dev), MINOR(st.st_dev),
310 (unsigned long long)st.st_ino);
311 buf0[len] = ' ';
312 snprintf(buf0 + MAPS_OFFSET, sizeof(buf0) - MAPS_OFFSET,
313 "/tmp/#%llu (deleted)\n", (unsigned long long)st.st_ino);
314
315 /* Test /proc/$PID/maps */
316 {
317 const size_t len = strlen(buf0) + (g_vsyscall ? strlen(str_vsyscall) : 0);
318 char buf[256];
319 ssize_t rv;
320 int fd;
321
322 snprintf(buf, sizeof(buf), "/proc/%u/maps", pid);
323 fd = open(buf, O_RDONLY);
324 if (fd == -1) {
325 return 1;
326 }
327 rv = read(fd, buf, sizeof(buf));
328 assert(rv == len);
329 assert(memcmp(buf, buf0, strlen(buf0)) == 0);
330 if (g_vsyscall) {
331 assert(memcmp(buf + strlen(buf0), str_vsyscall, strlen(str_vsyscall)) == 0);
332 }
333 }
334
335 /* Test /proc/$PID/smaps */
336 {
337 char buf[4096];
338 ssize_t rv;
339 int fd;
340
341 snprintf(buf, sizeof(buf), "/proc/%u/smaps", pid);
342 fd = open(buf, O_RDONLY);
343 if (fd == -1) {
344 return 1;
345 }
346 rv = read(fd, buf, sizeof(buf));
347 assert(0 <= rv && rv <= sizeof(buf));
348
349 assert(rv >= strlen(buf0));
350 assert(memcmp(buf, buf0, strlen(buf0)) == 0);
351
352 #define RSS1 "Rss: 4 kB\n"
353 #define RSS2 "Rss: 0 kB\n"
354 #define PSS1 "Pss: 4 kB\n"
355 #define PSS2 "Pss: 0 kB\n"
356 assert(memmem(buf, rv, RSS1, strlen(RSS1)) ||
357 memmem(buf, rv, RSS2, strlen(RSS2)));
358 assert(memmem(buf, rv, PSS1, strlen(PSS1)) ||
359 memmem(buf, rv, PSS2, strlen(PSS2)));
360
361 static const char *S[] = {
362 "Size: 4 kB\n",
363 "KernelPageSize: 4 kB\n",
364 "MMUPageSize: 4 kB\n",
365 "Anonymous: 0 kB\n",
366 "AnonHugePages: 0 kB\n",
367 "Shared_Hugetlb: 0 kB\n",
368 "Private_Hugetlb: 0 kB\n",
369 "Locked: 0 kB\n",
370 };
371 int i;
372
373 for (i = 0; i < ARRAY_SIZE(S); i++) {
374 assert(memmem(buf, rv, S[i], strlen(S[i])));
375 }
376
377 if (g_vsyscall) {
378 assert(memmem(buf, rv, str_vsyscall, strlen(str_vsyscall)));
379 }
380 }
381
382 /* Test /proc/$PID/smaps_rollup */
383 {
384 char bufr[256];
385 memset(bufr, ' ', sizeof(bufr));
386 len = snprintf(bufr, sizeof(bufr),
387 "%08lx-%08lx ---p 00000000 00:00 0",
388 VADDR, VADDR + PAGE_SIZE);
389 bufr[len] = ' ';
390 snprintf(bufr + MAPS_OFFSET, sizeof(bufr) - MAPS_OFFSET,
391 "[rollup]\n");
392
393 char buf[1024];
394 ssize_t rv;
395 int fd;
396
397 snprintf(buf, sizeof(buf), "/proc/%u/smaps_rollup", pid);
398 fd = open(buf, O_RDONLY);
399 if (fd == -1) {
400 return 1;
401 }
402 rv = read(fd, buf, sizeof(buf));
403 assert(0 <= rv && rv <= sizeof(buf));
404
405 assert(rv >= strlen(bufr));
406 assert(memcmp(buf, bufr, strlen(bufr)) == 0);
407
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)));
412
413 static const char *S[] = {
414 "Anonymous: 0 kB\n",
415 "AnonHugePages: 0 kB\n",
416 "Shared_Hugetlb: 0 kB\n",
417 "Private_Hugetlb: 0 kB\n",
418 "Locked: 0 kB\n",
419 };
420 int i;
421
422 for (i = 0; i < ARRAY_SIZE(S); i++) {
423 assert(memmem(buf, rv, S[i], strlen(S[i])));
424 }
425 }
426
427 /* Test /proc/$PID/statm */
428 {
429 char buf[64];
430 ssize_t rv;
431 int fd;
432
433 snprintf(buf, sizeof(buf), "/proc/%u/statm", pid);
434 fd = open(buf, O_RDONLY);
435 if (fd == -1) {
436 return 1;
437 }
438 rv = read(fd, buf, sizeof(buf));
439 assert(rv == 7 * 2);
440
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');
455 }
456
457 return 0;
458 }
459 #else
main(void)460 int main(void)
461 {
462 return 4;
463 }
464 #endif
465