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 /* 215 * 0: vsyscall VMA doesn't exist vsyscall=none 216 * 1: vsyscall VMA is --xp vsyscall=xonly 217 * 2: vsyscall VMA is r-xp vsyscall=emulate 218 */ 219 static volatile int g_vsyscall; 220 static const char *str_vsyscall; 221 222 static const char str_vsyscall_0[] = ""; 223 static const char str_vsyscall_1[] = 224 "ffffffffff600000-ffffffffff601000 --xp 00000000 00:00 0 [vsyscall]\n"; 225 static const char str_vsyscall_2[] = 226 "ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0 [vsyscall]\n"; 227 228 #ifdef __x86_64__ sigaction_SIGSEGV(int _,siginfo_t * __,void * ___)229 static void sigaction_SIGSEGV(int _, siginfo_t *__, void *___) 230 { 231 _exit(g_vsyscall); 232 } 233 234 /* 235 * vsyscall page can't be unmapped, probe it directly. 236 */ vsyscall(void)237 static void vsyscall(void) 238 { 239 pid_t pid; 240 int wstatus; 241 242 pid = fork(); 243 if (pid < 0) { 244 fprintf(stderr, "fork, errno %d\n", errno); 245 exit(1); 246 } 247 if (pid == 0) { 248 struct rlimit rlim = {0, 0}; 249 (void)setrlimit(RLIMIT_CORE, &rlim); 250 251 /* Hide "segfault at ffffffffff600000" messages. */ 252 struct sigaction act; 253 memset(&act, 0, sizeof(struct sigaction)); 254 act.sa_flags = SA_SIGINFO; 255 act.sa_sigaction = sigaction_SIGSEGV; 256 (void)sigaction(SIGSEGV, &act, NULL); 257 258 g_vsyscall = 0; 259 /* gettimeofday(NULL, NULL); */ 260 uint64_t rax = 0xffffffffff600000; 261 asm volatile ( 262 "call *%[rax]" 263 : [rax] "+a" (rax) 264 : "D" (NULL), "S" (NULL) 265 : "rcx", "r11" 266 ); 267 268 g_vsyscall = 1; 269 *(volatile int *)0xffffffffff600000UL; 270 271 g_vsyscall = 2; 272 exit(g_vsyscall); 273 } 274 waitpid(pid, &wstatus, 0); 275 if (WIFEXITED(wstatus)) { 276 g_vsyscall = WEXITSTATUS(wstatus); 277 } else { 278 fprintf(stderr, "error: wstatus %08x\n", wstatus); 279 exit(1); 280 } 281 } 282 main(void)283 int main(void) 284 { 285 int pipefd[2]; 286 int exec_fd; 287 288 vsyscall(); 289 switch (g_vsyscall) { 290 case 0: 291 str_vsyscall = str_vsyscall_0; 292 break; 293 case 1: 294 str_vsyscall = str_vsyscall_1; 295 break; 296 case 2: 297 str_vsyscall = str_vsyscall_2; 298 break; 299 default: 300 abort(); 301 } 302 303 atexit(ate); 304 305 make_private_tmp(); 306 307 /* Reserve fd 0 for 1-byte pipe ping from child. */ 308 close(0); 309 if (open("/", O_RDONLY|O_DIRECTORY|O_PATH) != 0) { 310 return 1; 311 } 312 313 exec_fd = make_exe(payload, sizeof(payload)); 314 315 if (pipe(pipefd) == -1) { 316 return 1; 317 } 318 if (dup2(pipefd[1], 0) != 0) { 319 return 1; 320 } 321 322 pid = fork(); 323 if (pid == -1) { 324 return 1; 325 } 326 if (pid == 0) { 327 sys_execveat(exec_fd, "", NULL, NULL, AT_EMPTY_PATH); 328 return 1; 329 } 330 331 char _; 332 if (read(pipefd[0], &_, 1) != 1) { 333 return 1; 334 } 335 336 struct stat st; 337 if (fstat(exec_fd, &st) == -1) { 338 return 1; 339 } 340 341 /* Generate "head -n1 /proc/$PID/maps" */ 342 char buf0[256]; 343 memset(buf0, ' ', sizeof(buf0)); 344 int len = snprintf(buf0, sizeof(buf0), 345 "%08lx-%08lx r-xp 00000000 %02lx:%02lx %llu", 346 VADDR, VADDR + PAGE_SIZE, 347 MAJOR(st.st_dev), MINOR(st.st_dev), 348 (unsigned long long)st.st_ino); 349 buf0[len] = ' '; 350 snprintf(buf0 + MAPS_OFFSET, sizeof(buf0) - MAPS_OFFSET, 351 "/tmp/#%llu (deleted)\n", (unsigned long long)st.st_ino); 352 353 /* Test /proc/$PID/maps */ 354 { 355 const size_t len = strlen(buf0) + strlen(str_vsyscall); 356 char buf[256]; 357 ssize_t rv; 358 int fd; 359 360 snprintf(buf, sizeof(buf), "/proc/%u/maps", pid); 361 fd = open(buf, O_RDONLY); 362 if (fd == -1) { 363 return 1; 364 } 365 rv = read(fd, buf, sizeof(buf)); 366 assert(rv == len); 367 assert(memcmp(buf, buf0, strlen(buf0)) == 0); 368 if (g_vsyscall > 0) { 369 assert(memcmp(buf + strlen(buf0), str_vsyscall, strlen(str_vsyscall)) == 0); 370 } 371 } 372 373 /* Test /proc/$PID/smaps */ 374 { 375 char buf[4096]; 376 ssize_t rv; 377 int fd; 378 379 snprintf(buf, sizeof(buf), "/proc/%u/smaps", pid); 380 fd = open(buf, O_RDONLY); 381 if (fd == -1) { 382 return 1; 383 } 384 rv = read(fd, buf, sizeof(buf)); 385 assert(0 <= rv && rv <= sizeof(buf)); 386 387 assert(rv >= strlen(buf0)); 388 assert(memcmp(buf, buf0, strlen(buf0)) == 0); 389 390 #define RSS1 "Rss: 4 kB\n" 391 #define RSS2 "Rss: 0 kB\n" 392 #define PSS1 "Pss: 4 kB\n" 393 #define PSS2 "Pss: 0 kB\n" 394 assert(memmem(buf, rv, RSS1, strlen(RSS1)) || 395 memmem(buf, rv, RSS2, strlen(RSS2))); 396 assert(memmem(buf, rv, PSS1, strlen(PSS1)) || 397 memmem(buf, rv, PSS2, strlen(PSS2))); 398 399 static const char *S[] = { 400 "Size: 4 kB\n", 401 "KernelPageSize: 4 kB\n", 402 "MMUPageSize: 4 kB\n", 403 "Anonymous: 0 kB\n", 404 "AnonHugePages: 0 kB\n", 405 "Shared_Hugetlb: 0 kB\n", 406 "Private_Hugetlb: 0 kB\n", 407 "Locked: 0 kB\n", 408 }; 409 int i; 410 411 for (i = 0; i < ARRAY_SIZE(S); i++) { 412 assert(memmem(buf, rv, S[i], strlen(S[i]))); 413 } 414 415 if (g_vsyscall > 0) { 416 assert(memmem(buf, rv, str_vsyscall, strlen(str_vsyscall))); 417 } 418 } 419 420 /* Test /proc/$PID/smaps_rollup */ 421 { 422 char bufr[256]; 423 memset(bufr, ' ', sizeof(bufr)); 424 len = snprintf(bufr, sizeof(bufr), 425 "%08lx-%08lx ---p 00000000 00:00 0", 426 VADDR, VADDR + PAGE_SIZE); 427 bufr[len] = ' '; 428 snprintf(bufr + MAPS_OFFSET, sizeof(bufr) - MAPS_OFFSET, 429 "[rollup]\n"); 430 431 char buf[1024]; 432 ssize_t rv; 433 int fd; 434 435 snprintf(buf, sizeof(buf), "/proc/%u/smaps_rollup", pid); 436 fd = open(buf, O_RDONLY); 437 if (fd == -1) { 438 return 1; 439 } 440 rv = read(fd, buf, sizeof(buf)); 441 assert(0 <= rv && rv <= sizeof(buf)); 442 443 assert(rv >= strlen(bufr)); 444 assert(memcmp(buf, bufr, strlen(bufr)) == 0); 445 446 assert(memmem(buf, rv, RSS1, strlen(RSS1)) || 447 memmem(buf, rv, RSS2, strlen(RSS2))); 448 assert(memmem(buf, rv, PSS1, strlen(PSS1)) || 449 memmem(buf, rv, PSS2, strlen(PSS2))); 450 451 static const char *S[] = { 452 "Anonymous: 0 kB\n", 453 "AnonHugePages: 0 kB\n", 454 "Shared_Hugetlb: 0 kB\n", 455 "Private_Hugetlb: 0 kB\n", 456 "Locked: 0 kB\n", 457 }; 458 int i; 459 460 for (i = 0; i < ARRAY_SIZE(S); i++) { 461 assert(memmem(buf, rv, S[i], strlen(S[i]))); 462 } 463 } 464 465 /* Test /proc/$PID/statm */ 466 { 467 char buf[64]; 468 ssize_t rv; 469 int fd; 470 471 snprintf(buf, sizeof(buf), "/proc/%u/statm", pid); 472 fd = open(buf, O_RDONLY); 473 if (fd == -1) { 474 return 1; 475 } 476 rv = read(fd, buf, sizeof(buf)); 477 assert(rv == 7 * 2); 478 479 assert(buf[0] == '1'); /* ->total_vm */ 480 assert(buf[1] == ' '); 481 assert(buf[2] == '0' || buf[2] == '1'); /* rss */ 482 assert(buf[3] == ' '); 483 assert(buf[4] == '0' || buf[2] == '1'); /* file rss */ 484 assert(buf[5] == ' '); 485 assert(buf[6] == '1'); /* ELF executable segments */ 486 assert(buf[7] == ' '); 487 assert(buf[8] == '0'); 488 assert(buf[9] == ' '); 489 assert(buf[10] == '0'); /* ->data_vm + ->stack_vm */ 490 assert(buf[11] == ' '); 491 assert(buf[12] == '0'); 492 assert(buf[13] == '\n'); 493 } 494 495 return 0; 496 } 497 #else main(void)498 int main(void) 499 { 500 return 4; 501 } 502 #endif 503