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 #include <linux/fs.h>
49
50 #include "../kselftest.h"
51
sys_execveat(int dirfd,const char * pathname,char ** argv,char ** envp,int flags)52 static inline long sys_execveat(int dirfd, const char *pathname, char **argv, char **envp, int flags)
53 {
54 return syscall(SYS_execveat, dirfd, pathname, argv, envp, flags);
55 }
56
make_private_tmp(void)57 static void make_private_tmp(void)
58 {
59 if (unshare(CLONE_NEWNS) == -1) {
60 if (errno == ENOSYS || errno == EPERM) {
61 exit(4);
62 }
63 exit(1);
64 }
65 if (mount(NULL, "/", NULL, MS_PRIVATE|MS_REC, NULL) == -1) {
66 exit(1);
67 }
68 if (mount(NULL, "/tmp", "tmpfs", 0, NULL) == -1) {
69 exit(1);
70 }
71 }
72
73 static pid_t pid = -1;
ate(void)74 static void ate(void)
75 {
76 if (pid > 0) {
77 kill(pid, SIGTERM);
78 }
79 }
80
81 struct elf64_hdr {
82 uint8_t e_ident[16];
83 uint16_t e_type;
84 uint16_t e_machine;
85 uint32_t e_version;
86 uint64_t e_entry;
87 uint64_t e_phoff;
88 uint64_t e_shoff;
89 uint32_t e_flags;
90 uint16_t e_ehsize;
91 uint16_t e_phentsize;
92 uint16_t e_phnum;
93 uint16_t e_shentsize;
94 uint16_t e_shnum;
95 uint16_t e_shstrndx;
96 };
97
98 struct elf64_phdr {
99 uint32_t p_type;
100 uint32_t p_flags;
101 uint64_t p_offset;
102 uint64_t p_vaddr;
103 uint64_t p_paddr;
104 uint64_t p_filesz;
105 uint64_t p_memsz;
106 uint64_t p_align;
107 };
108
109 #ifdef __x86_64__
110 #define PAGE_SIZE 4096
111 #define VADDR (1UL << 32)
112 #define MAPS_OFFSET 73
113
114 #define syscall 0x0f, 0x05
115 #define mov_rdi(x) \
116 0x48, 0xbf, \
117 (x)&0xff, ((x)>>8)&0xff, ((x)>>16)&0xff, ((x)>>24)&0xff, \
118 ((x)>>32)&0xff, ((x)>>40)&0xff, ((x)>>48)&0xff, ((x)>>56)&0xff
119
120 #define mov_rsi(x) \
121 0x48, 0xbe, \
122 (x)&0xff, ((x)>>8)&0xff, ((x)>>16)&0xff, ((x)>>24)&0xff, \
123 ((x)>>32)&0xff, ((x)>>40)&0xff, ((x)>>48)&0xff, ((x)>>56)&0xff
124
125 #define mov_eax(x) \
126 0xb8, (x)&0xff, ((x)>>8)&0xff, ((x)>>16)&0xff, ((x)>>24)&0xff
127
128 static const uint8_t payload[] = {
129 /* Casually unmap stack, vDSO and everything else. */
130 /* munmap */
131 mov_rdi(VADDR + 4096),
132 mov_rsi((1ULL << 47) - 4096 - VADDR - 4096),
133 mov_eax(11),
134 syscall,
135
136 /* Ping parent. */
137 /* write(0, &c, 1); */
138 0x31, 0xff, /* xor edi, edi */
139 0x48, 0x8d, 0x35, 0x00, 0x00, 0x00, 0x00, /* lea rsi, [rip] */
140 0xba, 0x01, 0x00, 0x00, 0x00, /* mov edx, 1 */
141 mov_eax(1),
142 syscall,
143
144 /* 1: pause(); */
145 mov_eax(34),
146 syscall,
147
148 0xeb, 0xf7, /* jmp 1b */
149 };
150
make_exe(const uint8_t * payload,size_t len)151 static int make_exe(const uint8_t *payload, size_t len)
152 {
153 struct elf64_hdr h;
154 struct elf64_phdr ph;
155
156 struct iovec iov[3] = {
157 {&h, sizeof(struct elf64_hdr)},
158 {&ph, sizeof(struct elf64_phdr)},
159 {(void *)payload, len},
160 };
161 int fd, fd1;
162 char buf[64];
163
164 memset(&h, 0, sizeof(h));
165 h.e_ident[0] = 0x7f;
166 h.e_ident[1] = 'E';
167 h.e_ident[2] = 'L';
168 h.e_ident[3] = 'F';
169 h.e_ident[4] = 2;
170 h.e_ident[5] = 1;
171 h.e_ident[6] = 1;
172 h.e_ident[7] = 0;
173 h.e_type = 2;
174 h.e_machine = 0x3e;
175 h.e_version = 1;
176 h.e_entry = VADDR + sizeof(struct elf64_hdr) + sizeof(struct elf64_phdr);
177 h.e_phoff = sizeof(struct elf64_hdr);
178 h.e_shoff = 0;
179 h.e_flags = 0;
180 h.e_ehsize = sizeof(struct elf64_hdr);
181 h.e_phentsize = sizeof(struct elf64_phdr);
182 h.e_phnum = 1;
183 h.e_shentsize = 0;
184 h.e_shnum = 0;
185 h.e_shstrndx = 0;
186
187 memset(&ph, 0, sizeof(ph));
188 ph.p_type = 1;
189 ph.p_flags = (1<<2)|1;
190 ph.p_offset = 0;
191 ph.p_vaddr = VADDR;
192 ph.p_paddr = 0;
193 ph.p_filesz = sizeof(struct elf64_hdr) + sizeof(struct elf64_phdr) + len;
194 ph.p_memsz = sizeof(struct elf64_hdr) + sizeof(struct elf64_phdr) + len;
195 ph.p_align = 4096;
196
197 fd = openat(AT_FDCWD, "/tmp", O_WRONLY|O_EXCL|O_TMPFILE, 0700);
198 if (fd == -1) {
199 exit(1);
200 }
201
202 if (writev(fd, iov, 3) != sizeof(struct elf64_hdr) + sizeof(struct elf64_phdr) + len) {
203 exit(1);
204 }
205
206 /* Avoid ETXTBSY on exec. */
207 snprintf(buf, sizeof(buf), "/proc/self/fd/%u", fd);
208 fd1 = open(buf, O_RDONLY|O_CLOEXEC);
209 close(fd);
210
211 return fd1;
212 }
213 #endif
214
215 /*
216 * 0: vsyscall VMA doesn't exist vsyscall=none
217 * 1: vsyscall VMA is --xp vsyscall=xonly
218 * 2: vsyscall VMA is r-xp vsyscall=emulate
219 */
220 static volatile int g_vsyscall;
221 static const char *str_vsyscall;
222
223 static const char str_vsyscall_0[] = "";
224 static const char str_vsyscall_1[] =
225 "ffffffffff600000-ffffffffff601000 --xp 00000000 00:00 0 [vsyscall]\n";
226 static const char str_vsyscall_2[] =
227 "ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0 [vsyscall]\n";
228
229 #ifdef __x86_64__
sigaction_SIGSEGV(int _,siginfo_t * __,void * ___)230 static void sigaction_SIGSEGV(int _, siginfo_t *__, void *___)
231 {
232 _exit(g_vsyscall);
233 }
234
235 /*
236 * vsyscall page can't be unmapped, probe it directly.
237 */
vsyscall(void)238 static void vsyscall(void)
239 {
240 pid_t pid;
241 int wstatus;
242
243 pid = fork();
244 if (pid < 0) {
245 fprintf(stderr, "fork, errno %d\n", errno);
246 exit(1);
247 }
248 if (pid == 0) {
249 struct rlimit rlim = {0, 0};
250 (void)setrlimit(RLIMIT_CORE, &rlim);
251
252 /* Hide "segfault at ffffffffff600000" messages. */
253 struct sigaction act;
254 memset(&act, 0, sizeof(struct sigaction));
255 act.sa_flags = SA_SIGINFO;
256 act.sa_sigaction = sigaction_SIGSEGV;
257 (void)sigaction(SIGSEGV, &act, NULL);
258
259 g_vsyscall = 0;
260 /* gettimeofday(NULL, NULL); */
261 uint64_t rax = 0xffffffffff600000;
262 asm volatile (
263 "call *%[rax]"
264 : [rax] "+a" (rax)
265 : "D" (NULL), "S" (NULL)
266 : "rcx", "r11"
267 );
268
269 g_vsyscall = 1;
270 *(volatile int *)0xffffffffff600000UL;
271
272 g_vsyscall = 2;
273 exit(g_vsyscall);
274 }
275 waitpid(pid, &wstatus, 0);
276 if (WIFEXITED(wstatus)) {
277 g_vsyscall = WEXITSTATUS(wstatus);
278 } else {
279 fprintf(stderr, "error: wstatus %08x\n", wstatus);
280 exit(1);
281 }
282 }
283
main(void)284 int main(void)
285 {
286 int pipefd[2];
287 int exec_fd;
288
289 vsyscall();
290 switch (g_vsyscall) {
291 case 0:
292 str_vsyscall = str_vsyscall_0;
293 break;
294 case 1:
295 str_vsyscall = str_vsyscall_1;
296 break;
297 case 2:
298 str_vsyscall = str_vsyscall_2;
299 break;
300 default:
301 abort();
302 }
303
304 atexit(ate);
305
306 make_private_tmp();
307
308 /* Reserve fd 0 for 1-byte pipe ping from child. */
309 close(0);
310 if (open("/", O_RDONLY|O_DIRECTORY|O_PATH) != 0) {
311 return 1;
312 }
313
314 exec_fd = make_exe(payload, sizeof(payload));
315
316 if (pipe(pipefd) == -1) {
317 return 1;
318 }
319 if (dup2(pipefd[1], 0) != 0) {
320 return 1;
321 }
322
323 pid = fork();
324 if (pid == -1) {
325 return 1;
326 }
327 if (pid == 0) {
328 sys_execveat(exec_fd, "", NULL, NULL, AT_EMPTY_PATH);
329 return 1;
330 }
331
332 char _;
333 if (read(pipefd[0], &_, 1) != 1) {
334 return 1;
335 }
336
337 struct stat st;
338 if (fstat(exec_fd, &st) == -1) {
339 return 1;
340 }
341
342 /* Generate "head -n1 /proc/$PID/maps" */
343 char buf0[256];
344 memset(buf0, ' ', sizeof(buf0));
345 int len = snprintf(buf0, sizeof(buf0),
346 "%08lx-%08lx r-xp 00000000 %02lx:%02lx %llu",
347 VADDR, VADDR + PAGE_SIZE,
348 MAJOR(st.st_dev), MINOR(st.st_dev),
349 (unsigned long long)st.st_ino);
350 buf0[len] = ' ';
351 snprintf(buf0 + MAPS_OFFSET, sizeof(buf0) - MAPS_OFFSET,
352 "/tmp/#%llu (deleted)\n", (unsigned long long)st.st_ino);
353
354 /* Test /proc/$PID/maps */
355 {
356 const size_t len = strlen(buf0) + strlen(str_vsyscall);
357 char buf[256];
358 ssize_t rv;
359 int fd;
360
361 snprintf(buf, sizeof(buf), "/proc/%u/maps", pid);
362 fd = open(buf, O_RDONLY);
363 if (fd == -1) {
364 return 1;
365 }
366 rv = read(fd, buf, sizeof(buf));
367 assert(rv == len);
368 assert(memcmp(buf, buf0, strlen(buf0)) == 0);
369 if (g_vsyscall > 0) {
370 assert(memcmp(buf + strlen(buf0), str_vsyscall, strlen(str_vsyscall)) == 0);
371 }
372 }
373
374 /* Test /proc/$PID/smaps */
375 {
376 char buf[4096];
377 ssize_t rv;
378 int fd;
379
380 snprintf(buf, sizeof(buf), "/proc/%u/smaps", pid);
381 fd = open(buf, O_RDONLY);
382 if (fd == -1) {
383 return 1;
384 }
385 rv = read(fd, buf, sizeof(buf));
386 assert(0 <= rv && rv <= sizeof(buf));
387
388 assert(rv >= strlen(buf0));
389 assert(memcmp(buf, buf0, strlen(buf0)) == 0);
390
391 #define RSS1 "Rss: 4 kB\n"
392 #define RSS2 "Rss: 0 kB\n"
393 #define PSS1 "Pss: 4 kB\n"
394 #define PSS2 "Pss: 0 kB\n"
395 assert(memmem(buf, rv, RSS1, strlen(RSS1)) ||
396 memmem(buf, rv, RSS2, strlen(RSS2)));
397 assert(memmem(buf, rv, PSS1, strlen(PSS1)) ||
398 memmem(buf, rv, PSS2, strlen(PSS2)));
399
400 static const char *S[] = {
401 "Size: 4 kB\n",
402 "KernelPageSize: 4 kB\n",
403 "MMUPageSize: 4 kB\n",
404 "Anonymous: 0 kB\n",
405 "AnonHugePages: 0 kB\n",
406 "Shared_Hugetlb: 0 kB\n",
407 "Private_Hugetlb: 0 kB\n",
408 "Locked: 0 kB\n",
409 };
410 int i;
411
412 for (i = 0; i < ARRAY_SIZE(S); i++) {
413 assert(memmem(buf, rv, S[i], strlen(S[i])));
414 }
415
416 if (g_vsyscall > 0) {
417 assert(memmem(buf, rv, str_vsyscall, strlen(str_vsyscall)));
418 }
419 }
420
421 /* Test /proc/$PID/smaps_rollup */
422 {
423 char bufr[256];
424 memset(bufr, ' ', sizeof(bufr));
425 len = snprintf(bufr, sizeof(bufr),
426 "%08lx-%08lx ---p 00000000 00:00 0",
427 VADDR, VADDR + PAGE_SIZE);
428 bufr[len] = ' ';
429 snprintf(bufr + MAPS_OFFSET, sizeof(bufr) - MAPS_OFFSET,
430 "[rollup]\n");
431
432 char buf[1024];
433 ssize_t rv;
434 int fd;
435
436 snprintf(buf, sizeof(buf), "/proc/%u/smaps_rollup", pid);
437 fd = open(buf, O_RDONLY);
438 if (fd == -1) {
439 return 1;
440 }
441 rv = read(fd, buf, sizeof(buf));
442 assert(0 <= rv && rv <= sizeof(buf));
443
444 assert(rv >= strlen(bufr));
445 assert(memcmp(buf, bufr, strlen(bufr)) == 0);
446
447 assert(memmem(buf, rv, RSS1, strlen(RSS1)) ||
448 memmem(buf, rv, RSS2, strlen(RSS2)));
449 assert(memmem(buf, rv, PSS1, strlen(PSS1)) ||
450 memmem(buf, rv, PSS2, strlen(PSS2)));
451
452 static const char *S[] = {
453 "Anonymous: 0 kB\n",
454 "AnonHugePages: 0 kB\n",
455 "Shared_Hugetlb: 0 kB\n",
456 "Private_Hugetlb: 0 kB\n",
457 "Locked: 0 kB\n",
458 };
459 int i;
460
461 for (i = 0; i < ARRAY_SIZE(S); i++) {
462 assert(memmem(buf, rv, S[i], strlen(S[i])));
463 }
464 }
465
466 /* Test /proc/$PID/statm */
467 {
468 char buf[64];
469 ssize_t rv;
470 int fd;
471
472 snprintf(buf, sizeof(buf), "/proc/%u/statm", pid);
473 fd = open(buf, O_RDONLY);
474 if (fd == -1) {
475 return 1;
476 }
477 rv = read(fd, buf, sizeof(buf));
478 assert(rv == 7 * 2);
479
480 assert(buf[0] == '1'); /* ->total_vm */
481 assert(buf[1] == ' ');
482 assert(buf[2] == '0' || buf[2] == '1'); /* rss */
483 assert(buf[3] == ' ');
484 assert(buf[4] == '0' || buf[2] == '1'); /* file rss */
485 assert(buf[5] == ' ');
486 assert(buf[6] == '1'); /* ELF executable segments */
487 assert(buf[7] == ' ');
488 assert(buf[8] == '0');
489 assert(buf[9] == ' ');
490 assert(buf[10] == '0'); /* ->data_vm + ->stack_vm */
491 assert(buf[11] == ' ');
492 assert(buf[12] == '0');
493 assert(buf[13] == '\n');
494 }
495
496 /* Test PROCMAP_QUERY ioctl() for /proc/$PID/maps */
497 {
498 char path_buf[256], exp_path_buf[256];
499 struct procmap_query q;
500 int fd, err;
501
502 snprintf(path_buf, sizeof(path_buf), "/proc/%u/maps", pid);
503 fd = open(path_buf, O_RDONLY);
504 if (fd == -1)
505 return 1;
506
507 /* CASE 1: exact MATCH at VADDR */
508 memset(&q, 0, sizeof(q));
509 q.size = sizeof(q);
510 q.query_addr = VADDR;
511 q.query_flags = 0;
512 q.vma_name_addr = (__u64)(unsigned long)path_buf;
513 q.vma_name_size = sizeof(path_buf);
514
515 err = ioctl(fd, PROCMAP_QUERY, &q);
516 assert(err == 0);
517
518 assert(q.query_addr == VADDR);
519 assert(q.query_flags == 0);
520
521 assert(q.vma_flags == (PROCMAP_QUERY_VMA_READABLE | PROCMAP_QUERY_VMA_EXECUTABLE));
522 assert(q.vma_start == VADDR);
523 assert(q.vma_end == VADDR + PAGE_SIZE);
524 assert(q.vma_page_size == PAGE_SIZE);
525
526 assert(q.vma_offset == 0);
527 assert(q.inode == st.st_ino);
528 assert(q.dev_major == MAJOR(st.st_dev));
529 assert(q.dev_minor == MINOR(st.st_dev));
530
531 snprintf(exp_path_buf, sizeof(exp_path_buf),
532 "/tmp/#%llu (deleted)", (unsigned long long)st.st_ino);
533 assert(q.vma_name_size == strlen(exp_path_buf) + 1);
534 assert(strcmp(path_buf, exp_path_buf) == 0);
535
536 /* CASE 2: NO MATCH at VADDR-1 */
537 memset(&q, 0, sizeof(q));
538 q.size = sizeof(q);
539 q.query_addr = VADDR - 1;
540 q.query_flags = 0; /* exact match */
541
542 err = ioctl(fd, PROCMAP_QUERY, &q);
543 err = err < 0 ? -errno : 0;
544 assert(err == -ENOENT);
545
546 /* CASE 3: MATCH COVERING_OR_NEXT_VMA at VADDR - 1 */
547 memset(&q, 0, sizeof(q));
548 q.size = sizeof(q);
549 q.query_addr = VADDR - 1;
550 q.query_flags = PROCMAP_QUERY_COVERING_OR_NEXT_VMA;
551
552 err = ioctl(fd, PROCMAP_QUERY, &q);
553 assert(err == 0);
554
555 assert(q.query_addr == VADDR - 1);
556 assert(q.query_flags == PROCMAP_QUERY_COVERING_OR_NEXT_VMA);
557 assert(q.vma_start == VADDR);
558 assert(q.vma_end == VADDR + PAGE_SIZE);
559
560 /* CASE 4: NO MATCH at VADDR + PAGE_SIZE */
561 memset(&q, 0, sizeof(q));
562 q.size = sizeof(q);
563 q.query_addr = VADDR + PAGE_SIZE; /* point right after the VMA */
564 q.query_flags = PROCMAP_QUERY_COVERING_OR_NEXT_VMA;
565
566 err = ioctl(fd, PROCMAP_QUERY, &q);
567 err = err < 0 ? -errno : 0;
568 assert(err == -ENOENT);
569
570 /* CASE 5: NO MATCH WRITABLE at VADDR */
571 memset(&q, 0, sizeof(q));
572 q.size = sizeof(q);
573 q.query_addr = VADDR;
574 q.query_flags = PROCMAP_QUERY_VMA_WRITABLE;
575
576 err = ioctl(fd, PROCMAP_QUERY, &q);
577 err = err < 0 ? -errno : 0;
578 assert(err == -ENOENT);
579 }
580
581 return 0;
582 }
583 #else
main(void)584 int main(void)
585 {
586 return 4;
587 }
588 #endif
589