Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1// SPDX-License-Identifier: GPL-2.0-or-later
2
3#define _GNU_SOURCE
4#include "kselftest_harness.h"
5#include <asm-generic/mman.h> /* Force the import of the tools version. */
6#include <assert.h>
7#include <errno.h>
8#include <fcntl.h>
9#include <linux/limits.h>
10#include <linux/userfaultfd.h>
11#include <linux/fs.h>
12#include <setjmp.h>
13#include <signal.h>
14#include <stdbool.h>
15#include <stdio.h>
16#include <stdlib.h>
17#include <string.h>
18#include <sys/ioctl.h>
19#include <sys/mman.h>
20#include <sys/syscall.h>
21#include <sys/uio.h>
22#include <unistd.h>
23#include "vm_util.h"
24#include "thp_settings.h"
25
26#include "../pidfd/pidfd.h"
27
28/*
29 * Ignore the checkpatch warning, as per the C99 standard, section 7.14.1.1:
30 *
31 * "If the signal occurs other than as the result of calling the abort or raise
32 * function, the behavior is undefined if the signal handler refers to any
33 * object with static storage duration other than by assigning a value to an
34 * object declared as volatile sig_atomic_t"
35 */
36static volatile sig_atomic_t signal_jump_set;
37static sigjmp_buf signal_jmp_buf;
38
39/*
40 * How is the test backing the mapping being tested?
41 */
42enum backing_type {
43 ANON_BACKED,
44 SHMEM_BACKED,
45 LOCAL_FILE_BACKED,
46};
47
48FIXTURE(guard_regions)
49{
50 unsigned long page_size;
51 char path[PATH_MAX];
52 int fd;
53};
54
55FIXTURE_VARIANT(guard_regions)
56{
57 enum backing_type backing;
58};
59
60FIXTURE_VARIANT_ADD(guard_regions, anon)
61{
62 .backing = ANON_BACKED,
63};
64
65FIXTURE_VARIANT_ADD(guard_regions, shmem)
66{
67 .backing = SHMEM_BACKED,
68};
69
70FIXTURE_VARIANT_ADD(guard_regions, file)
71{
72 .backing = LOCAL_FILE_BACKED,
73};
74
75static bool is_anon_backed(const FIXTURE_VARIANT(guard_regions) * variant)
76{
77 switch (variant->backing) {
78 case ANON_BACKED:
79 case SHMEM_BACKED:
80 return true;
81 default:
82 return false;
83 }
84}
85
86static void *mmap_(FIXTURE_DATA(guard_regions) * self,
87 const FIXTURE_VARIANT(guard_regions) * variant,
88 void *addr, size_t length, int prot, int extra_flags,
89 off_t offset)
90{
91 int fd;
92 int flags = extra_flags;
93
94 switch (variant->backing) {
95 case ANON_BACKED:
96 flags |= MAP_PRIVATE | MAP_ANON;
97 fd = -1;
98 offset = 0;
99 break;
100 case SHMEM_BACKED:
101 case LOCAL_FILE_BACKED:
102 flags |= MAP_SHARED;
103 fd = self->fd;
104 break;
105 default:
106 ksft_exit_fail();
107 break;
108 }
109
110 return mmap(addr, length, prot, flags, fd, offset);
111}
112
113static int userfaultfd(int flags)
114{
115 return syscall(SYS_userfaultfd, flags);
116}
117
118static void handle_fatal(int c)
119{
120 if (!signal_jump_set)
121 return;
122
123 siglongjmp(signal_jmp_buf, c);
124}
125
126static ssize_t sys_process_madvise(int pidfd, const struct iovec *iovec,
127 size_t n, int advice, unsigned int flags)
128{
129 return syscall(__NR_process_madvise, pidfd, iovec, n, advice, flags);
130}
131
132/*
133 * Enable our signal catcher and try to read/write the specified buffer. The
134 * return value indicates whether the read/write succeeds without a fatal
135 * signal.
136 */
137static bool try_access_buf(char *ptr, bool write)
138{
139 bool failed;
140
141 /* Tell signal handler to jump back here on fatal signal. */
142 signal_jump_set = true;
143 /* If a fatal signal arose, we will jump back here and failed is set. */
144 failed = sigsetjmp(signal_jmp_buf, 0) != 0;
145
146 if (!failed) {
147 if (write)
148 *ptr = 'x';
149 else
150 FORCE_READ(*ptr);
151 }
152
153 signal_jump_set = false;
154 return !failed;
155}
156
157/* Try and read from a buffer, return true if no fatal signal. */
158static bool try_read_buf(char *ptr)
159{
160 return try_access_buf(ptr, false);
161}
162
163/* Try and write to a buffer, return true if no fatal signal. */
164static bool try_write_buf(char *ptr)
165{
166 return try_access_buf(ptr, true);
167}
168
169/*
170 * Try and BOTH read from AND write to a buffer, return true if BOTH operations
171 * succeed.
172 */
173static bool try_read_write_buf(char *ptr)
174{
175 return try_read_buf(ptr) && try_write_buf(ptr);
176}
177
178static void setup_sighandler(void)
179{
180 struct sigaction act = {
181 .sa_handler = &handle_fatal,
182 .sa_flags = SA_NODEFER,
183 };
184
185 sigemptyset(&act.sa_mask);
186 if (sigaction(SIGSEGV, &act, NULL))
187 ksft_exit_fail_perror("sigaction");
188}
189
190static void teardown_sighandler(void)
191{
192 struct sigaction act = {
193 .sa_handler = SIG_DFL,
194 .sa_flags = SA_NODEFER,
195 };
196
197 sigemptyset(&act.sa_mask);
198 sigaction(SIGSEGV, &act, NULL);
199}
200
201static int open_file(const char *prefix, char *path)
202{
203 int fd;
204
205 snprintf(path, PATH_MAX, "%sguard_regions_test_file_XXXXXX", prefix);
206 fd = mkstemp(path);
207 if (fd < 0)
208 ksft_exit_fail_perror("mkstemp");
209
210 return fd;
211}
212
213/* Establish a varying pattern in a buffer. */
214static void set_pattern(char *ptr, size_t num_pages, size_t page_size)
215{
216 size_t i;
217
218 for (i = 0; i < num_pages; i++) {
219 char *ptr2 = &ptr[i * page_size];
220
221 memset(ptr2, 'a' + (i % 26), page_size);
222 }
223}
224
225/*
226 * Check that a buffer contains the pattern set by set_pattern(), starting at a
227 * page offset of pgoff within the buffer.
228 */
229static bool check_pattern_offset(char *ptr, size_t num_pages, size_t page_size,
230 size_t pgoff)
231{
232 size_t i;
233
234 for (i = 0; i < num_pages * page_size; i++) {
235 size_t offset = pgoff * page_size + i;
236 char actual = ptr[offset];
237 char expected = 'a' + ((offset / page_size) % 26);
238
239 if (actual != expected)
240 return false;
241 }
242
243 return true;
244}
245
246/* Check that a buffer contains the pattern set by set_pattern(). */
247static bool check_pattern(char *ptr, size_t num_pages, size_t page_size)
248{
249 return check_pattern_offset(ptr, num_pages, page_size, 0);
250}
251
252/* Determine if a buffer contains only repetitions of a specified char. */
253static bool is_buf_eq(char *buf, size_t size, char chr)
254{
255 size_t i;
256
257 for (i = 0; i < size; i++) {
258 if (buf[i] != chr)
259 return false;
260 }
261
262 return true;
263}
264
265/*
266 * Some file systems have issues with merging due to changing merge-sensitive
267 * parameters in the .mmap callback, and prior to .mmap_prepare being
268 * implemented everywhere this will now result in an unexpected failure to
269 * merge (e.g. - overlayfs).
270 *
271 * Perform a simple test to see if the local file system suffers from this, if
272 * it does then we can skip test logic that assumes local file system merging is
273 * sane.
274 */
275static bool local_fs_has_sane_mmap(FIXTURE_DATA(guard_regions) * self,
276 const FIXTURE_VARIANT(guard_regions) * variant)
277{
278 const unsigned long page_size = self->page_size;
279 char *ptr, *ptr2;
280 struct procmap_fd procmap;
281
282 if (variant->backing != LOCAL_FILE_BACKED)
283 return true;
284
285 /* Map 10 pages. */
286 ptr = mmap_(self, variant, NULL, 10 * page_size, PROT_READ | PROT_WRITE, 0, 0);
287 if (ptr == MAP_FAILED)
288 return false;
289 /* Unmap the middle. */
290 munmap(&ptr[5 * page_size], page_size);
291
292 /* Map again. */
293 ptr2 = mmap_(self, variant, &ptr[5 * page_size], page_size, PROT_READ | PROT_WRITE,
294 MAP_FIXED, 5 * page_size);
295
296 if (ptr2 == MAP_FAILED)
297 return false;
298
299 /* Now make sure they all merged. */
300 if (open_self_procmap(&procmap) != 0)
301 return false;
302 if (!find_vma_procmap(&procmap, ptr))
303 return false;
304 if (procmap.query.vma_start != (unsigned long)ptr)
305 return false;
306 if (procmap.query.vma_end != (unsigned long)ptr + 10 * page_size)
307 return false;
308 close_procmap(&procmap);
309
310 return true;
311}
312
313FIXTURE_SETUP(guard_regions)
314{
315 self->page_size = (unsigned long)sysconf(_SC_PAGESIZE);
316 setup_sighandler();
317
318 switch (variant->backing) {
319 case ANON_BACKED:
320 return;
321 case LOCAL_FILE_BACKED:
322 self->fd = open_file("", self->path);
323 break;
324 case SHMEM_BACKED:
325 self->fd = memfd_create(self->path, 0);
326 break;
327 }
328
329 /* We truncate file to at least 100 pages, tests can modify as needed. */
330 ASSERT_EQ(ftruncate(self->fd, 100 * self->page_size), 0);
331};
332
333FIXTURE_TEARDOWN_PARENT(guard_regions)
334{
335 teardown_sighandler();
336
337 if (variant->backing == ANON_BACKED)
338 return;
339
340 if (self->fd >= 0)
341 close(self->fd);
342
343 if (self->path[0] != '\0')
344 unlink(self->path);
345}
346
347TEST_F(guard_regions, basic)
348{
349 const unsigned long NUM_PAGES = 10;
350 const unsigned long page_size = self->page_size;
351 char *ptr;
352 int i;
353
354 ptr = mmap_(self, variant, NULL, NUM_PAGES * page_size,
355 PROT_READ | PROT_WRITE, 0, 0);
356 ASSERT_NE(ptr, MAP_FAILED);
357
358 /* Trivially assert we can touch the first page. */
359 ASSERT_TRUE(try_read_write_buf(ptr));
360
361 ASSERT_EQ(madvise(ptr, page_size, MADV_GUARD_INSTALL), 0);
362
363 /* Establish that 1st page SIGSEGV's. */
364 ASSERT_FALSE(try_read_write_buf(ptr));
365
366 /* Ensure we can touch everything else.*/
367 for (i = 1; i < NUM_PAGES; i++) {
368 char *curr = &ptr[i * page_size];
369
370 ASSERT_TRUE(try_read_write_buf(curr));
371 }
372
373 /* Establish a guard page at the end of the mapping. */
374 ASSERT_EQ(madvise(&ptr[(NUM_PAGES - 1) * page_size], page_size,
375 MADV_GUARD_INSTALL), 0);
376
377 /* Check that both guard pages result in SIGSEGV. */
378 ASSERT_FALSE(try_read_write_buf(ptr));
379 ASSERT_FALSE(try_read_write_buf(&ptr[(NUM_PAGES - 1) * page_size]));
380
381 /* Remove the first guard page. */
382 ASSERT_FALSE(madvise(ptr, page_size, MADV_GUARD_REMOVE));
383
384 /* Make sure we can touch it. */
385 ASSERT_TRUE(try_read_write_buf(ptr));
386
387 /* Remove the last guard page. */
388 ASSERT_FALSE(madvise(&ptr[(NUM_PAGES - 1) * page_size], page_size,
389 MADV_GUARD_REMOVE));
390
391 /* Make sure we can touch it. */
392 ASSERT_TRUE(try_read_write_buf(&ptr[(NUM_PAGES - 1) * page_size]));
393
394 /*
395 * Test setting a _range_ of pages, namely the first 3. The first of
396 * these be faulted in, so this also tests that we can install guard
397 * pages over backed pages.
398 */
399 ASSERT_EQ(madvise(ptr, 3 * page_size, MADV_GUARD_INSTALL), 0);
400
401 /* Make sure they are all guard pages. */
402 for (i = 0; i < 3; i++) {
403 char *curr = &ptr[i * page_size];
404
405 ASSERT_FALSE(try_read_write_buf(curr));
406 }
407
408 /* Make sure the rest are not. */
409 for (i = 3; i < NUM_PAGES; i++) {
410 char *curr = &ptr[i * page_size];
411
412 ASSERT_TRUE(try_read_write_buf(curr));
413 }
414
415 /* Remove guard pages. */
416 ASSERT_EQ(madvise(ptr, NUM_PAGES * page_size, MADV_GUARD_REMOVE), 0);
417
418 /* Now make sure we can touch everything. */
419 for (i = 0; i < NUM_PAGES; i++) {
420 char *curr = &ptr[i * page_size];
421
422 ASSERT_TRUE(try_read_write_buf(curr));
423 }
424
425 /*
426 * Now remove all guard pages, make sure we don't remove existing
427 * entries.
428 */
429 ASSERT_EQ(madvise(ptr, NUM_PAGES * page_size, MADV_GUARD_REMOVE), 0);
430
431 for (i = 0; i < NUM_PAGES * page_size; i += page_size) {
432 char chr = ptr[i];
433
434 ASSERT_EQ(chr, 'x');
435 }
436
437 ASSERT_EQ(munmap(ptr, NUM_PAGES * page_size), 0);
438}
439
440/* Assert that operations applied across multiple VMAs work as expected. */
441TEST_F(guard_regions, multi_vma)
442{
443 const unsigned long page_size = self->page_size;
444 char *ptr_region, *ptr, *ptr1, *ptr2, *ptr3;
445 int i;
446
447 /* Reserve a 100 page region over which we can install VMAs. */
448 ptr_region = mmap_(self, variant, NULL, 100 * page_size,
449 PROT_NONE, 0, 0);
450 ASSERT_NE(ptr_region, MAP_FAILED);
451
452 /* Place a VMA of 10 pages size at the start of the region. */
453 ptr1 = mmap_(self, variant, ptr_region, 10 * page_size,
454 PROT_READ | PROT_WRITE, MAP_FIXED, 0);
455 ASSERT_NE(ptr1, MAP_FAILED);
456
457 /* Place a VMA of 5 pages size 50 pages into the region. */
458 ptr2 = mmap_(self, variant, &ptr_region[50 * page_size], 5 * page_size,
459 PROT_READ | PROT_WRITE, MAP_FIXED, 0);
460 ASSERT_NE(ptr2, MAP_FAILED);
461
462 /* Place a VMA of 20 pages size at the end of the region. */
463 ptr3 = mmap_(self, variant, &ptr_region[80 * page_size], 20 * page_size,
464 PROT_READ | PROT_WRITE, MAP_FIXED, 0);
465 ASSERT_NE(ptr3, MAP_FAILED);
466
467 /* Unmap gaps. */
468 ASSERT_EQ(munmap(&ptr_region[10 * page_size], 40 * page_size), 0);
469 ASSERT_EQ(munmap(&ptr_region[55 * page_size], 25 * page_size), 0);
470
471 /*
472 * We end up with VMAs like this:
473 *
474 * 0 10 .. 50 55 .. 80 100
475 * [---] [---] [---]
476 */
477
478 /*
479 * Now mark the whole range as guard pages and make sure all VMAs are as
480 * such.
481 */
482
483 /*
484 * madvise() is certifiable and lets you perform operations over gaps,
485 * everything works, but it indicates an error and errno is set to
486 * -ENOMEM. Also if anything runs out of memory it is set to
487 * -ENOMEM. You are meant to guess which is which.
488 */
489 ASSERT_EQ(madvise(ptr_region, 100 * page_size, MADV_GUARD_INSTALL), -1);
490 ASSERT_EQ(errno, ENOMEM);
491
492 for (i = 0; i < 10; i++) {
493 char *curr = &ptr1[i * page_size];
494
495 ASSERT_FALSE(try_read_write_buf(curr));
496 }
497
498 for (i = 0; i < 5; i++) {
499 char *curr = &ptr2[i * page_size];
500
501 ASSERT_FALSE(try_read_write_buf(curr));
502 }
503
504 for (i = 0; i < 20; i++) {
505 char *curr = &ptr3[i * page_size];
506
507 ASSERT_FALSE(try_read_write_buf(curr));
508 }
509
510 /* Now remove guar pages over range and assert the opposite. */
511
512 ASSERT_EQ(madvise(ptr_region, 100 * page_size, MADV_GUARD_REMOVE), -1);
513 ASSERT_EQ(errno, ENOMEM);
514
515 for (i = 0; i < 10; i++) {
516 char *curr = &ptr1[i * page_size];
517
518 ASSERT_TRUE(try_read_write_buf(curr));
519 }
520
521 for (i = 0; i < 5; i++) {
522 char *curr = &ptr2[i * page_size];
523
524 ASSERT_TRUE(try_read_write_buf(curr));
525 }
526
527 for (i = 0; i < 20; i++) {
528 char *curr = &ptr3[i * page_size];
529
530 ASSERT_TRUE(try_read_write_buf(curr));
531 }
532
533 /* Now map incompatible VMAs in the gaps. */
534 ptr = mmap_(self, variant, &ptr_region[10 * page_size], 40 * page_size,
535 PROT_READ | PROT_WRITE | PROT_EXEC, MAP_FIXED, 0);
536 ASSERT_NE(ptr, MAP_FAILED);
537 ptr = mmap_(self, variant, &ptr_region[55 * page_size], 25 * page_size,
538 PROT_READ | PROT_WRITE | PROT_EXEC, MAP_FIXED, 0);
539 ASSERT_NE(ptr, MAP_FAILED);
540
541 /*
542 * We end up with VMAs like this:
543 *
544 * 0 10 .. 50 55 .. 80 100
545 * [---][xxxx][---][xxxx][---]
546 *
547 * Where 'x' signifies VMAs that cannot be merged with those adjacent to
548 * them.
549 */
550
551 /* Multiple VMAs adjacent to one another should result in no error. */
552 ASSERT_EQ(madvise(ptr_region, 100 * page_size, MADV_GUARD_INSTALL), 0);
553 for (i = 0; i < 100; i++) {
554 char *curr = &ptr_region[i * page_size];
555
556 ASSERT_FALSE(try_read_write_buf(curr));
557 }
558 ASSERT_EQ(madvise(ptr_region, 100 * page_size, MADV_GUARD_REMOVE), 0);
559 for (i = 0; i < 100; i++) {
560 char *curr = &ptr_region[i * page_size];
561
562 ASSERT_TRUE(try_read_write_buf(curr));
563 }
564
565 /* Cleanup. */
566 ASSERT_EQ(munmap(ptr_region, 100 * page_size), 0);
567}
568
569/*
570 * Assert that batched operations performed using process_madvise() work as
571 * expected.
572 */
573TEST_F(guard_regions, process_madvise)
574{
575 const unsigned long page_size = self->page_size;
576 char *ptr_region, *ptr1, *ptr2, *ptr3;
577 ssize_t count;
578 struct iovec vec[6];
579
580 /* Reserve region to map over. */
581 ptr_region = mmap_(self, variant, NULL, 100 * page_size,
582 PROT_NONE, 0, 0);
583 ASSERT_NE(ptr_region, MAP_FAILED);
584
585 /*
586 * 10 pages offset 1 page into reserve region. We MAP_POPULATE so we
587 * overwrite existing entries and test this code path against
588 * overwriting existing entries.
589 */
590 ptr1 = mmap_(self, variant, &ptr_region[page_size], 10 * page_size,
591 PROT_READ | PROT_WRITE, MAP_FIXED | MAP_POPULATE, 0);
592 ASSERT_NE(ptr1, MAP_FAILED);
593 /* We want guard markers at start/end of each VMA. */
594 vec[0].iov_base = ptr1;
595 vec[0].iov_len = page_size;
596 vec[1].iov_base = &ptr1[9 * page_size];
597 vec[1].iov_len = page_size;
598
599 /* 5 pages offset 50 pages into reserve region. */
600 ptr2 = mmap_(self, variant, &ptr_region[50 * page_size], 5 * page_size,
601 PROT_READ | PROT_WRITE, MAP_FIXED, 0);
602 ASSERT_NE(ptr2, MAP_FAILED);
603 vec[2].iov_base = ptr2;
604 vec[2].iov_len = page_size;
605 vec[3].iov_base = &ptr2[4 * page_size];
606 vec[3].iov_len = page_size;
607
608 /* 20 pages offset 79 pages into reserve region. */
609 ptr3 = mmap_(self, variant, &ptr_region[79 * page_size], 20 * page_size,
610 PROT_READ | PROT_WRITE, MAP_FIXED, 0);
611 ASSERT_NE(ptr3, MAP_FAILED);
612 vec[4].iov_base = ptr3;
613 vec[4].iov_len = page_size;
614 vec[5].iov_base = &ptr3[19 * page_size];
615 vec[5].iov_len = page_size;
616
617 /* Free surrounding VMAs. */
618 ASSERT_EQ(munmap(ptr_region, page_size), 0);
619 ASSERT_EQ(munmap(&ptr_region[11 * page_size], 39 * page_size), 0);
620 ASSERT_EQ(munmap(&ptr_region[55 * page_size], 24 * page_size), 0);
621 ASSERT_EQ(munmap(&ptr_region[99 * page_size], page_size), 0);
622
623 /* Now guard in one step. */
624 count = sys_process_madvise(PIDFD_SELF, vec, 6, MADV_GUARD_INSTALL, 0);
625
626 /* OK we don't have permission to do this, skip. */
627 if (count == -1 && errno == EPERM)
628 SKIP(return, "No process_madvise() permissions, try running as root.\n");
629
630 /* Returns the number of bytes advised. */
631 ASSERT_EQ(count, 6 * page_size);
632
633 /* Now make sure the guarding was applied. */
634
635 ASSERT_FALSE(try_read_write_buf(ptr1));
636 ASSERT_FALSE(try_read_write_buf(&ptr1[9 * page_size]));
637
638 ASSERT_FALSE(try_read_write_buf(ptr2));
639 ASSERT_FALSE(try_read_write_buf(&ptr2[4 * page_size]));
640
641 ASSERT_FALSE(try_read_write_buf(ptr3));
642 ASSERT_FALSE(try_read_write_buf(&ptr3[19 * page_size]));
643
644 /* Now do the same with unguard... */
645 count = sys_process_madvise(PIDFD_SELF, vec, 6, MADV_GUARD_REMOVE, 0);
646
647 /* ...and everything should now succeed. */
648
649 ASSERT_TRUE(try_read_write_buf(ptr1));
650 ASSERT_TRUE(try_read_write_buf(&ptr1[9 * page_size]));
651
652 ASSERT_TRUE(try_read_write_buf(ptr2));
653 ASSERT_TRUE(try_read_write_buf(&ptr2[4 * page_size]));
654
655 ASSERT_TRUE(try_read_write_buf(ptr3));
656 ASSERT_TRUE(try_read_write_buf(&ptr3[19 * page_size]));
657
658 /* Cleanup. */
659 ASSERT_EQ(munmap(ptr1, 10 * page_size), 0);
660 ASSERT_EQ(munmap(ptr2, 5 * page_size), 0);
661 ASSERT_EQ(munmap(ptr3, 20 * page_size), 0);
662}
663
664/* Assert that unmapping ranges does not leave guard markers behind. */
665TEST_F(guard_regions, munmap)
666{
667 const unsigned long page_size = self->page_size;
668 char *ptr, *ptr_new1, *ptr_new2;
669
670 ptr = mmap_(self, variant, NULL, 10 * page_size,
671 PROT_READ | PROT_WRITE, 0, 0);
672 ASSERT_NE(ptr, MAP_FAILED);
673
674 /* Guard first and last pages. */
675 ASSERT_EQ(madvise(ptr, page_size, MADV_GUARD_INSTALL), 0);
676 ASSERT_EQ(madvise(&ptr[9 * page_size], page_size, MADV_GUARD_INSTALL), 0);
677
678 /* Assert that they are guarded. */
679 ASSERT_FALSE(try_read_write_buf(ptr));
680 ASSERT_FALSE(try_read_write_buf(&ptr[9 * page_size]));
681
682 /* Unmap them. */
683 ASSERT_EQ(munmap(ptr, page_size), 0);
684 ASSERT_EQ(munmap(&ptr[9 * page_size], page_size), 0);
685
686 /* Map over them.*/
687 ptr_new1 = mmap_(self, variant, ptr, page_size, PROT_READ | PROT_WRITE,
688 MAP_FIXED, 0);
689 ASSERT_NE(ptr_new1, MAP_FAILED);
690 ptr_new2 = mmap_(self, variant, &ptr[9 * page_size], page_size,
691 PROT_READ | PROT_WRITE, MAP_FIXED, 0);
692 ASSERT_NE(ptr_new2, MAP_FAILED);
693
694 /* Assert that they are now not guarded. */
695 ASSERT_TRUE(try_read_write_buf(ptr_new1));
696 ASSERT_TRUE(try_read_write_buf(ptr_new2));
697
698 /* Cleanup. */
699 ASSERT_EQ(munmap(ptr, 10 * page_size), 0);
700}
701
702/* Assert that mprotect() operations have no bearing on guard markers. */
703TEST_F(guard_regions, mprotect)
704{
705 const unsigned long page_size = self->page_size;
706 char *ptr;
707 int i;
708
709 ptr = mmap_(self, variant, NULL, 10 * page_size,
710 PROT_READ | PROT_WRITE, 0, 0);
711 ASSERT_NE(ptr, MAP_FAILED);
712
713 /* Guard the middle of the range. */
714 ASSERT_EQ(madvise(&ptr[5 * page_size], 2 * page_size,
715 MADV_GUARD_INSTALL), 0);
716
717 /* Assert that it is indeed guarded. */
718 ASSERT_FALSE(try_read_write_buf(&ptr[5 * page_size]));
719 ASSERT_FALSE(try_read_write_buf(&ptr[6 * page_size]));
720
721 /* Now make these pages read-only. */
722 ASSERT_EQ(mprotect(&ptr[5 * page_size], 2 * page_size, PROT_READ), 0);
723
724 /* Make sure the range is still guarded. */
725 ASSERT_FALSE(try_read_buf(&ptr[5 * page_size]));
726 ASSERT_FALSE(try_read_buf(&ptr[6 * page_size]));
727
728 /* Make sure we can guard again without issue.*/
729 ASSERT_EQ(madvise(&ptr[5 * page_size], 2 * page_size,
730 MADV_GUARD_INSTALL), 0);
731
732 /* Make sure the range is, yet again, still guarded. */
733 ASSERT_FALSE(try_read_buf(&ptr[5 * page_size]));
734 ASSERT_FALSE(try_read_buf(&ptr[6 * page_size]));
735
736 /* Now unguard the whole range. */
737 ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_GUARD_REMOVE), 0);
738
739 /* Make sure the whole range is readable. */
740 for (i = 0; i < 10; i++) {
741 char *curr = &ptr[i * page_size];
742
743 ASSERT_TRUE(try_read_buf(curr));
744 }
745
746 /* Cleanup. */
747 ASSERT_EQ(munmap(ptr, 10 * page_size), 0);
748}
749
750/* Split and merge VMAs and make sure guard pages still behave. */
751TEST_F(guard_regions, split_merge)
752{
753 const unsigned long page_size = self->page_size;
754 char *ptr, *ptr_new;
755 int i;
756
757 ptr = mmap_(self, variant, NULL, 10 * page_size,
758 PROT_READ | PROT_WRITE, 0, 0);
759 ASSERT_NE(ptr, MAP_FAILED);
760
761 /* Guard the whole range. */
762 ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_GUARD_INSTALL), 0);
763
764 /* Make sure the whole range is guarded. */
765 for (i = 0; i < 10; i++) {
766 char *curr = &ptr[i * page_size];
767
768 ASSERT_FALSE(try_read_write_buf(curr));
769 }
770
771 /* Now unmap some pages in the range so we split. */
772 ASSERT_EQ(munmap(&ptr[2 * page_size], page_size), 0);
773 ASSERT_EQ(munmap(&ptr[5 * page_size], page_size), 0);
774 ASSERT_EQ(munmap(&ptr[8 * page_size], page_size), 0);
775
776 /* Make sure the remaining ranges are guarded post-split. */
777 for (i = 0; i < 2; i++) {
778 char *curr = &ptr[i * page_size];
779
780 ASSERT_FALSE(try_read_write_buf(curr));
781 }
782 for (i = 2; i < 5; i++) {
783 char *curr = &ptr[i * page_size];
784
785 ASSERT_FALSE(try_read_write_buf(curr));
786 }
787 for (i = 6; i < 8; i++) {
788 char *curr = &ptr[i * page_size];
789
790 ASSERT_FALSE(try_read_write_buf(curr));
791 }
792 for (i = 9; i < 10; i++) {
793 char *curr = &ptr[i * page_size];
794
795 ASSERT_FALSE(try_read_write_buf(curr));
796 }
797
798 /* Now map them again - the unmap will have cleared the guards. */
799 ptr_new = mmap_(self, variant, &ptr[2 * page_size], page_size,
800 PROT_READ | PROT_WRITE, MAP_FIXED, 0);
801 ASSERT_NE(ptr_new, MAP_FAILED);
802 ptr_new = mmap_(self, variant, &ptr[5 * page_size], page_size,
803 PROT_READ | PROT_WRITE, MAP_FIXED, 0);
804 ASSERT_NE(ptr_new, MAP_FAILED);
805 ptr_new = mmap_(self, variant, &ptr[8 * page_size], page_size,
806 PROT_READ | PROT_WRITE, MAP_FIXED, 0);
807 ASSERT_NE(ptr_new, MAP_FAILED);
808
809 /* Now make sure guard pages are established. */
810 for (i = 0; i < 10; i++) {
811 char *curr = &ptr[i * page_size];
812 bool result = try_read_write_buf(curr);
813 bool expect_true = i == 2 || i == 5 || i == 8;
814
815 ASSERT_TRUE(expect_true ? result : !result);
816 }
817
818 /* Now guard everything again. */
819 ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_GUARD_INSTALL), 0);
820
821 /* Make sure the whole range is guarded. */
822 for (i = 0; i < 10; i++) {
823 char *curr = &ptr[i * page_size];
824
825 ASSERT_FALSE(try_read_write_buf(curr));
826 }
827
828 /* Now split the range into three. */
829 ASSERT_EQ(mprotect(ptr, 3 * page_size, PROT_READ), 0);
830 ASSERT_EQ(mprotect(&ptr[7 * page_size], 3 * page_size, PROT_READ), 0);
831
832 /* Make sure the whole range is guarded for read. */
833 for (i = 0; i < 10; i++) {
834 char *curr = &ptr[i * page_size];
835
836 ASSERT_FALSE(try_read_buf(curr));
837 }
838
839 /* Now reset protection bits so we merge the whole thing. */
840 ASSERT_EQ(mprotect(ptr, 3 * page_size, PROT_READ | PROT_WRITE), 0);
841 ASSERT_EQ(mprotect(&ptr[7 * page_size], 3 * page_size,
842 PROT_READ | PROT_WRITE), 0);
843
844 /* Make sure the whole range is still guarded. */
845 for (i = 0; i < 10; i++) {
846 char *curr = &ptr[i * page_size];
847
848 ASSERT_FALSE(try_read_write_buf(curr));
849 }
850
851 /* Split range into 3 again... */
852 ASSERT_EQ(mprotect(ptr, 3 * page_size, PROT_READ), 0);
853 ASSERT_EQ(mprotect(&ptr[7 * page_size], 3 * page_size, PROT_READ), 0);
854
855 /* ...and unguard the whole range. */
856 ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_GUARD_REMOVE), 0);
857
858 /* Make sure the whole range is remedied for read. */
859 for (i = 0; i < 10; i++) {
860 char *curr = &ptr[i * page_size];
861
862 ASSERT_TRUE(try_read_buf(curr));
863 }
864
865 /* Merge them again. */
866 ASSERT_EQ(mprotect(ptr, 3 * page_size, PROT_READ | PROT_WRITE), 0);
867 ASSERT_EQ(mprotect(&ptr[7 * page_size], 3 * page_size,
868 PROT_READ | PROT_WRITE), 0);
869
870 /* Now ensure the merged range is remedied for read/write. */
871 for (i = 0; i < 10; i++) {
872 char *curr = &ptr[i * page_size];
873
874 ASSERT_TRUE(try_read_write_buf(curr));
875 }
876
877 /* Cleanup. */
878 ASSERT_EQ(munmap(ptr, 10 * page_size), 0);
879}
880
881/* Assert that MADV_DONTNEED does not remove guard markers. */
882TEST_F(guard_regions, dontneed)
883{
884 const unsigned long page_size = self->page_size;
885 char *ptr;
886 int i;
887
888 ptr = mmap_(self, variant, NULL, 10 * page_size,
889 PROT_READ | PROT_WRITE, 0, 0);
890 ASSERT_NE(ptr, MAP_FAILED);
891
892 /* Back the whole range. */
893 for (i = 0; i < 10; i++) {
894 char *curr = &ptr[i * page_size];
895
896 *curr = 'y';
897 }
898
899 /* Guard every other page. */
900 for (i = 0; i < 10; i += 2) {
901 char *curr = &ptr[i * page_size];
902 int res = madvise(curr, page_size, MADV_GUARD_INSTALL);
903
904 ASSERT_EQ(res, 0);
905 }
906
907 /* Indicate that we don't need any of the range. */
908 ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_DONTNEED), 0);
909
910 /* Check to ensure guard markers are still in place. */
911 for (i = 0; i < 10; i++) {
912 char *curr = &ptr[i * page_size];
913 bool result = try_read_buf(curr);
914
915 if (i % 2 == 0) {
916 ASSERT_FALSE(result);
917 } else {
918 ASSERT_TRUE(result);
919 switch (variant->backing) {
920 case ANON_BACKED:
921 /* If anon, then we get a zero page. */
922 ASSERT_EQ(*curr, '\0');
923 break;
924 default:
925 /* Otherwise, we get the file data. */
926 ASSERT_EQ(*curr, 'y');
927 break;
928 }
929 }
930
931 /* Now write... */
932 result = try_write_buf(&ptr[i * page_size]);
933
934 /* ...and make sure same result. */
935 ASSERT_TRUE(i % 2 != 0 ? result : !result);
936 }
937
938 /* Cleanup. */
939 ASSERT_EQ(munmap(ptr, 10 * page_size), 0);
940}
941
942/* Assert that mlock()'ed pages work correctly with guard markers. */
943TEST_F(guard_regions, mlock)
944{
945 const unsigned long page_size = self->page_size;
946 char *ptr;
947 int i;
948
949 ptr = mmap_(self, variant, NULL, 10 * page_size,
950 PROT_READ | PROT_WRITE, 0, 0);
951 ASSERT_NE(ptr, MAP_FAILED);
952
953 /* Populate. */
954 for (i = 0; i < 10; i++) {
955 char *curr = &ptr[i * page_size];
956
957 *curr = 'y';
958 }
959
960 /* Lock. */
961 ASSERT_EQ(mlock(ptr, 10 * page_size), 0);
962
963 /* Now try to guard, should fail with EINVAL. */
964 ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_GUARD_INSTALL), -1);
965 ASSERT_EQ(errno, EINVAL);
966
967 /* OK unlock. */
968 ASSERT_EQ(munlock(ptr, 10 * page_size), 0);
969
970 /* Guard first half of range, should now succeed. */
971 ASSERT_EQ(madvise(ptr, 5 * page_size, MADV_GUARD_INSTALL), 0);
972
973 /* Make sure guard works. */
974 for (i = 0; i < 10; i++) {
975 char *curr = &ptr[i * page_size];
976 bool result = try_read_write_buf(curr);
977
978 if (i < 5) {
979 ASSERT_FALSE(result);
980 } else {
981 ASSERT_TRUE(result);
982 ASSERT_EQ(*curr, 'x');
983 }
984 }
985
986 /*
987 * Now lock the latter part of the range. We can't lock the guard pages,
988 * as this would result in the pages being populated and the guarding
989 * would cause this to error out.
990 */
991 ASSERT_EQ(mlock(&ptr[5 * page_size], 5 * page_size), 0);
992
993 /*
994 * Now remove guard pages, we permit mlock()'d ranges to have guard
995 * pages removed as it is a non-destructive operation.
996 */
997 ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_GUARD_REMOVE), 0);
998
999 /* Now check that no guard pages remain. */
1000 for (i = 0; i < 10; i++) {
1001 char *curr = &ptr[i * page_size];
1002
1003 ASSERT_TRUE(try_read_write_buf(curr));
1004 }
1005
1006 /* Cleanup. */
1007 ASSERT_EQ(munmap(ptr, 10 * page_size), 0);
1008}
1009
1010/*
1011 * Assert that moving, extending and shrinking memory via mremap() retains
1012 * guard markers where possible.
1013 *
1014 * - Moving a mapping alone should retain markers as they are.
1015 */
1016TEST_F(guard_regions, mremap_move)
1017{
1018 const unsigned long page_size = self->page_size;
1019 char *ptr, *ptr_new;
1020
1021 /* Map 5 pages. */
1022 ptr = mmap_(self, variant, NULL, 5 * page_size,
1023 PROT_READ | PROT_WRITE, 0, 0);
1024 ASSERT_NE(ptr, MAP_FAILED);
1025
1026 /* Place guard markers at both ends of the 5 page span. */
1027 ASSERT_EQ(madvise(ptr, page_size, MADV_GUARD_INSTALL), 0);
1028 ASSERT_EQ(madvise(&ptr[4 * page_size], page_size, MADV_GUARD_INSTALL), 0);
1029
1030 /* Make sure the guard pages are in effect. */
1031 ASSERT_FALSE(try_read_write_buf(ptr));
1032 ASSERT_FALSE(try_read_write_buf(&ptr[4 * page_size]));
1033
1034 /* Map a new region we will move this range into. Doing this ensures
1035 * that we have reserved a range to map into.
1036 */
1037 ptr_new = mmap_(self, variant, NULL, 5 * page_size, PROT_NONE, 0, 0);
1038 ASSERT_NE(ptr_new, MAP_FAILED);
1039
1040 ASSERT_EQ(mremap(ptr, 5 * page_size, 5 * page_size,
1041 MREMAP_MAYMOVE | MREMAP_FIXED, ptr_new), ptr_new);
1042
1043 /* Make sure the guard markers are retained. */
1044 ASSERT_FALSE(try_read_write_buf(ptr_new));
1045 ASSERT_FALSE(try_read_write_buf(&ptr_new[4 * page_size]));
1046
1047 /*
1048 * Clean up - we only need reference the new pointer as we overwrote the
1049 * PROT_NONE range and moved the existing one.
1050 */
1051 munmap(ptr_new, 5 * page_size);
1052}
1053
1054/*
1055 * Assert that moving, extending and shrinking memory via mremap() retains
1056 * guard markers where possible.
1057 *
1058 * Expanding should retain guard pages, only now in different position. The user
1059 * will have to remove guard pages manually to fix up (they'd have to do the
1060 * same if it were a PROT_NONE mapping).
1061 */
1062TEST_F(guard_regions, mremap_expand)
1063{
1064 const unsigned long page_size = self->page_size;
1065 char *ptr, *ptr_new;
1066
1067 /* Map 10 pages... */
1068 ptr = mmap_(self, variant, NULL, 10 * page_size,
1069 PROT_READ | PROT_WRITE, 0, 0);
1070 ASSERT_NE(ptr, MAP_FAILED);
1071 /* ...But unmap the last 5 so we can ensure we can expand into them. */
1072 ASSERT_EQ(munmap(&ptr[5 * page_size], 5 * page_size), 0);
1073
1074 /* Place guard markers at both ends of the 5 page span. */
1075 ASSERT_EQ(madvise(ptr, page_size, MADV_GUARD_INSTALL), 0);
1076 ASSERT_EQ(madvise(&ptr[4 * page_size], page_size, MADV_GUARD_INSTALL), 0);
1077
1078 /* Make sure the guarding is in effect. */
1079 ASSERT_FALSE(try_read_write_buf(ptr));
1080 ASSERT_FALSE(try_read_write_buf(&ptr[4 * page_size]));
1081
1082 /* Now expand to 10 pages. */
1083 ptr = mremap(ptr, 5 * page_size, 10 * page_size, 0);
1084 ASSERT_NE(ptr, MAP_FAILED);
1085
1086 /*
1087 * Make sure the guard markers are retained in their original positions.
1088 */
1089 ASSERT_FALSE(try_read_write_buf(ptr));
1090 ASSERT_FALSE(try_read_write_buf(&ptr[4 * page_size]));
1091
1092 /* Reserve a region which we can move to and expand into. */
1093 ptr_new = mmap_(self, variant, NULL, 20 * page_size, PROT_NONE, 0, 0);
1094 ASSERT_NE(ptr_new, MAP_FAILED);
1095
1096 /* Now move and expand into it. */
1097 ptr = mremap(ptr, 10 * page_size, 20 * page_size,
1098 MREMAP_MAYMOVE | MREMAP_FIXED, ptr_new);
1099 ASSERT_EQ(ptr, ptr_new);
1100
1101 /*
1102 * Again, make sure the guard markers are retained in their original positions.
1103 */
1104 ASSERT_FALSE(try_read_write_buf(ptr));
1105 ASSERT_FALSE(try_read_write_buf(&ptr[4 * page_size]));
1106
1107 /*
1108 * A real user would have to remove guard markers, but would reasonably
1109 * expect all characteristics of the mapping to be retained, including
1110 * guard markers.
1111 */
1112
1113 /* Cleanup. */
1114 munmap(ptr, 20 * page_size);
1115}
1116/*
1117 * Assert that moving, extending and shrinking memory via mremap() retains
1118 * guard markers where possible.
1119 *
1120 * Shrinking will result in markers that are shrunk over being removed. Again,
1121 * if the user were using a PROT_NONE mapping they'd have to manually fix this
1122 * up also so this is OK.
1123 */
1124TEST_F(guard_regions, mremap_shrink)
1125{
1126 const unsigned long page_size = self->page_size;
1127 char *ptr;
1128 int i;
1129
1130 /* Map 5 pages. */
1131 ptr = mmap_(self, variant, NULL, 5 * page_size,
1132 PROT_READ | PROT_WRITE, 0, 0);
1133 ASSERT_NE(ptr, MAP_FAILED);
1134
1135 /* Place guard markers at both ends of the 5 page span. */
1136 ASSERT_EQ(madvise(ptr, page_size, MADV_GUARD_INSTALL), 0);
1137 ASSERT_EQ(madvise(&ptr[4 * page_size], page_size, MADV_GUARD_INSTALL), 0);
1138
1139 /* Make sure the guarding is in effect. */
1140 ASSERT_FALSE(try_read_write_buf(ptr));
1141 ASSERT_FALSE(try_read_write_buf(&ptr[4 * page_size]));
1142
1143 /* Now shrink to 3 pages. */
1144 ptr = mremap(ptr, 5 * page_size, 3 * page_size, MREMAP_MAYMOVE);
1145 ASSERT_NE(ptr, MAP_FAILED);
1146
1147 /* We expect the guard marker at the start to be retained... */
1148 ASSERT_FALSE(try_read_write_buf(ptr));
1149
1150 /* ...But remaining pages will not have guard markers. */
1151 for (i = 1; i < 3; i++) {
1152 char *curr = &ptr[i * page_size];
1153
1154 ASSERT_TRUE(try_read_write_buf(curr));
1155 }
1156
1157 /*
1158 * As with expansion, a real user would have to remove guard pages and
1159 * fixup. But you'd have to do similar manual things with PROT_NONE
1160 * mappings too.
1161 */
1162
1163 /*
1164 * If we expand back to the original size, the end marker will, of
1165 * course, no longer be present.
1166 */
1167 ptr = mremap(ptr, 3 * page_size, 5 * page_size, 0);
1168 ASSERT_NE(ptr, MAP_FAILED);
1169
1170 /* Again, we expect the guard marker at the start to be retained... */
1171 ASSERT_FALSE(try_read_write_buf(ptr));
1172
1173 /* ...But remaining pages will not have guard markers. */
1174 for (i = 1; i < 5; i++) {
1175 char *curr = &ptr[i * page_size];
1176
1177 ASSERT_TRUE(try_read_write_buf(curr));
1178 }
1179
1180 /* Cleanup. */
1181 munmap(ptr, 5 * page_size);
1182}
1183
1184/*
1185 * Assert that forking a process with VMAs that do not have VM_WIPEONFORK set
1186 * retain guard pages.
1187 */
1188TEST_F(guard_regions, fork)
1189{
1190 const unsigned long page_size = self->page_size;
1191 char *ptr;
1192 pid_t pid;
1193 int i;
1194
1195 /* Map 10 pages. */
1196 ptr = mmap_(self, variant, NULL, 10 * page_size,
1197 PROT_READ | PROT_WRITE, 0, 0);
1198 ASSERT_NE(ptr, MAP_FAILED);
1199
1200 /* Establish guard pages in the first 5 pages. */
1201 ASSERT_EQ(madvise(ptr, 5 * page_size, MADV_GUARD_INSTALL), 0);
1202
1203 pid = fork();
1204 ASSERT_NE(pid, -1);
1205 if (!pid) {
1206 /* This is the child process now. */
1207
1208 /* Assert that the guarding is in effect. */
1209 for (i = 0; i < 10; i++) {
1210 char *curr = &ptr[i * page_size];
1211 bool result = try_read_write_buf(curr);
1212
1213 ASSERT_TRUE(i >= 5 ? result : !result);
1214 }
1215
1216 /* Now unguard the range.*/
1217 ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_GUARD_REMOVE), 0);
1218
1219 exit(0);
1220 }
1221
1222 /* Parent process. */
1223
1224 /* Parent simply waits on child. */
1225 waitpid(pid, NULL, 0);
1226
1227 /* Child unguard does not impact parent page table state. */
1228 for (i = 0; i < 10; i++) {
1229 char *curr = &ptr[i * page_size];
1230 bool result = try_read_write_buf(curr);
1231
1232 ASSERT_TRUE(i >= 5 ? result : !result);
1233 }
1234
1235 /* Cleanup. */
1236 ASSERT_EQ(munmap(ptr, 10 * page_size), 0);
1237}
1238
1239/*
1240 * Assert expected behaviour after we fork populated ranges of anonymous memory
1241 * and then guard and unguard the range.
1242 */
1243TEST_F(guard_regions, fork_cow)
1244{
1245 const unsigned long page_size = self->page_size;
1246 char *ptr;
1247 pid_t pid;
1248 int i;
1249
1250 if (variant->backing != ANON_BACKED)
1251 SKIP(return, "CoW only supported on anon mappings");
1252
1253 /* Map 10 pages. */
1254 ptr = mmap_(self, variant, NULL, 10 * page_size,
1255 PROT_READ | PROT_WRITE, 0, 0);
1256 ASSERT_NE(ptr, MAP_FAILED);
1257
1258 /* Populate range. */
1259 for (i = 0; i < 10 * page_size; i++) {
1260 char chr = 'a' + (i % 26);
1261
1262 ptr[i] = chr;
1263 }
1264
1265 pid = fork();
1266 ASSERT_NE(pid, -1);
1267 if (!pid) {
1268 /* This is the child process now. */
1269
1270 /* Ensure the range is as expected. */
1271 for (i = 0; i < 10 * page_size; i++) {
1272 char expected = 'a' + (i % 26);
1273 char actual = ptr[i];
1274
1275 ASSERT_EQ(actual, expected);
1276 }
1277
1278 /* Establish guard pages across the whole range. */
1279 ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_GUARD_INSTALL), 0);
1280 /* Remove it. */
1281 ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_GUARD_REMOVE), 0);
1282
1283 /*
1284 * By removing the guard pages, the page tables will be
1285 * cleared. Assert that we are looking at the zero page now.
1286 */
1287 for (i = 0; i < 10 * page_size; i++) {
1288 char actual = ptr[i];
1289
1290 ASSERT_EQ(actual, '\0');
1291 }
1292
1293 exit(0);
1294 }
1295
1296 /* Parent process. */
1297
1298 /* Parent simply waits on child. */
1299 waitpid(pid, NULL, 0);
1300
1301 /* Ensure the range is unchanged in parent anon range. */
1302 for (i = 0; i < 10 * page_size; i++) {
1303 char expected = 'a' + (i % 26);
1304 char actual = ptr[i];
1305
1306 ASSERT_EQ(actual, expected);
1307 }
1308
1309 /* Cleanup. */
1310 ASSERT_EQ(munmap(ptr, 10 * page_size), 0);
1311}
1312
1313/*
1314 * Assert that forking a process with VMAs that do have VM_WIPEONFORK set
1315 * behave as expected.
1316 */
1317TEST_F(guard_regions, fork_wipeonfork)
1318{
1319 const unsigned long page_size = self->page_size;
1320 char *ptr;
1321 pid_t pid;
1322 int i;
1323
1324 if (variant->backing != ANON_BACKED)
1325 SKIP(return, "Wipe on fork only supported on anon mappings");
1326
1327 /* Map 10 pages. */
1328 ptr = mmap_(self, variant, NULL, 10 * page_size,
1329 PROT_READ | PROT_WRITE, 0, 0);
1330 ASSERT_NE(ptr, MAP_FAILED);
1331
1332 /* Mark wipe on fork. */
1333 ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_WIPEONFORK), 0);
1334
1335 /* Guard the first 5 pages. */
1336 ASSERT_EQ(madvise(ptr, 5 * page_size, MADV_GUARD_INSTALL), 0);
1337
1338 pid = fork();
1339 ASSERT_NE(pid, -1);
1340 if (!pid) {
1341 /* This is the child process now. */
1342
1343 /* Guard will have been wiped. */
1344 for (i = 0; i < 10; i++) {
1345 char *curr = &ptr[i * page_size];
1346
1347 ASSERT_TRUE(try_read_write_buf(curr));
1348 }
1349
1350 exit(0);
1351 }
1352
1353 /* Parent process. */
1354
1355 waitpid(pid, NULL, 0);
1356
1357 /* Guard markers should be in effect.*/
1358 for (i = 0; i < 10; i++) {
1359 char *curr = &ptr[i * page_size];
1360 bool result = try_read_write_buf(curr);
1361
1362 ASSERT_TRUE(i >= 5 ? result : !result);
1363 }
1364
1365 /* Cleanup. */
1366 ASSERT_EQ(munmap(ptr, 10 * page_size), 0);
1367}
1368
1369/* Ensure that MADV_FREE retains guard entries as expected. */
1370TEST_F(guard_regions, lazyfree)
1371{
1372 const unsigned long page_size = self->page_size;
1373 char *ptr;
1374 int i;
1375
1376 if (variant->backing != ANON_BACKED)
1377 SKIP(return, "MADV_FREE only supported on anon mappings");
1378
1379 /* Map 10 pages. */
1380 ptr = mmap_(self, variant, NULL, 10 * page_size,
1381 PROT_READ | PROT_WRITE, 0, 0);
1382 ASSERT_NE(ptr, MAP_FAILED);
1383
1384 /* Guard range. */
1385 ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_GUARD_INSTALL), 0);
1386
1387 /* Ensure guarded. */
1388 for (i = 0; i < 10; i++) {
1389 char *curr = &ptr[i * page_size];
1390
1391 ASSERT_FALSE(try_read_write_buf(curr));
1392 }
1393
1394 /* Lazyfree range. */
1395 ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_FREE), 0);
1396
1397 /* This should leave the guard markers in place. */
1398 for (i = 0; i < 10; i++) {
1399 char *curr = &ptr[i * page_size];
1400
1401 ASSERT_FALSE(try_read_write_buf(curr));
1402 }
1403
1404 /* Cleanup. */
1405 ASSERT_EQ(munmap(ptr, 10 * page_size), 0);
1406}
1407
1408/* Ensure that MADV_POPULATE_READ, MADV_POPULATE_WRITE behave as expected. */
1409TEST_F(guard_regions, populate)
1410{
1411 const unsigned long page_size = self->page_size;
1412 char *ptr;
1413
1414 /* Map 10 pages. */
1415 ptr = mmap_(self, variant, NULL, 10 * page_size,
1416 PROT_READ | PROT_WRITE, 0, 0);
1417 ASSERT_NE(ptr, MAP_FAILED);
1418
1419 /* Guard range. */
1420 ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_GUARD_INSTALL), 0);
1421
1422 /* Populate read should error out... */
1423 ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_POPULATE_READ), -1);
1424 ASSERT_EQ(errno, EFAULT);
1425
1426 /* ...as should populate write. */
1427 ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_POPULATE_WRITE), -1);
1428 ASSERT_EQ(errno, EFAULT);
1429
1430 /* Cleanup. */
1431 ASSERT_EQ(munmap(ptr, 10 * page_size), 0);
1432}
1433
1434/* Ensure that MADV_COLD, MADV_PAGEOUT do not remove guard markers. */
1435TEST_F(guard_regions, cold_pageout)
1436{
1437 const unsigned long page_size = self->page_size;
1438 char *ptr;
1439 int i;
1440
1441 /* Map 10 pages. */
1442 ptr = mmap_(self, variant, NULL, 10 * page_size,
1443 PROT_READ | PROT_WRITE, 0, 0);
1444 ASSERT_NE(ptr, MAP_FAILED);
1445
1446 /* Guard range. */
1447 ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_GUARD_INSTALL), 0);
1448
1449 /* Ensured guarded. */
1450 for (i = 0; i < 10; i++) {
1451 char *curr = &ptr[i * page_size];
1452
1453 ASSERT_FALSE(try_read_write_buf(curr));
1454 }
1455
1456 /* Now mark cold. This should have no impact on guard markers. */
1457 ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_COLD), 0);
1458
1459 /* Should remain guarded. */
1460 for (i = 0; i < 10; i++) {
1461 char *curr = &ptr[i * page_size];
1462
1463 ASSERT_FALSE(try_read_write_buf(curr));
1464 }
1465
1466 /* OK, now page out. This should equally, have no effect on markers. */
1467 ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_PAGEOUT), 0);
1468
1469 /* Should remain guarded. */
1470 for (i = 0; i < 10; i++) {
1471 char *curr = &ptr[i * page_size];
1472
1473 ASSERT_FALSE(try_read_write_buf(curr));
1474 }
1475
1476 /* Cleanup. */
1477 ASSERT_EQ(munmap(ptr, 10 * page_size), 0);
1478}
1479
1480/* Ensure that guard pages do not break userfaultd. */
1481TEST_F(guard_regions, uffd)
1482{
1483 const unsigned long page_size = self->page_size;
1484 int uffd;
1485 char *ptr;
1486 int i;
1487 struct uffdio_api api = {
1488 .api = UFFD_API,
1489 .features = 0,
1490 };
1491 struct uffdio_register reg;
1492 struct uffdio_range range;
1493
1494 if (!is_anon_backed(variant))
1495 SKIP(return, "uffd only works on anon backing");
1496
1497 /* Set up uffd. */
1498 uffd = userfaultfd(0);
1499 if (uffd == -1) {
1500 switch (errno) {
1501 case EPERM:
1502 SKIP(return, "No userfaultfd permissions, try running as root.");
1503 break;
1504 case ENOSYS:
1505 SKIP(return, "userfaultfd is not supported/not enabled.");
1506 break;
1507 default:
1508 ksft_exit_fail_msg("userfaultfd failed with %s\n",
1509 strerror(errno));
1510 break;
1511 }
1512 }
1513
1514 ASSERT_NE(uffd, -1);
1515
1516 ASSERT_EQ(ioctl(uffd, UFFDIO_API, &api), 0);
1517
1518 /* Map 10 pages. */
1519 ptr = mmap_(self, variant, NULL, 10 * page_size,
1520 PROT_READ | PROT_WRITE, 0, 0);
1521 ASSERT_NE(ptr, MAP_FAILED);
1522
1523 /* Register the range with uffd. */
1524 range.start = (unsigned long)ptr;
1525 range.len = 10 * page_size;
1526 reg.range = range;
1527 reg.mode = UFFDIO_REGISTER_MODE_MISSING;
1528 ASSERT_EQ(ioctl(uffd, UFFDIO_REGISTER, ®), 0);
1529
1530 /* Guard the range. This should not trigger the uffd. */
1531 ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_GUARD_INSTALL), 0);
1532
1533 /* The guarding should behave as usual with no uffd intervention. */
1534 for (i = 0; i < 10; i++) {
1535 char *curr = &ptr[i * page_size];
1536
1537 ASSERT_FALSE(try_read_write_buf(curr));
1538 }
1539
1540 /* Cleanup. */
1541 ASSERT_EQ(ioctl(uffd, UFFDIO_UNREGISTER, &range), 0);
1542 close(uffd);
1543 ASSERT_EQ(munmap(ptr, 10 * page_size), 0);
1544}
1545
1546/*
1547 * Mark a region within a file-backed mapping using MADV_SEQUENTIAL so we
1548 * aggressively read-ahead, then install guard regions and assert that it
1549 * behaves correctly.
1550 *
1551 * We page out using MADV_PAGEOUT before checking guard regions so we drop page
1552 * cache folios, meaning we maximise the possibility of some broken readahead.
1553 */
1554TEST_F(guard_regions, madvise_sequential)
1555{
1556 char *ptr;
1557 int i;
1558 const unsigned long page_size = self->page_size;
1559
1560 if (variant->backing == ANON_BACKED)
1561 SKIP(return, "MADV_SEQUENTIAL meaningful only for file-backed");
1562
1563 ptr = mmap_(self, variant, NULL, 10 * page_size,
1564 PROT_READ | PROT_WRITE, 0, 0);
1565 ASSERT_NE(ptr, MAP_FAILED);
1566
1567 /* Establish a pattern of data in the file. */
1568 set_pattern(ptr, 10, page_size);
1569 ASSERT_TRUE(check_pattern(ptr, 10, page_size));
1570
1571 /* Mark it as being accessed sequentially. */
1572 ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_SEQUENTIAL), 0);
1573
1574 /* Mark every other page a guard page. */
1575 for (i = 0; i < 10; i += 2) {
1576 char *ptr2 = &ptr[i * page_size];
1577
1578 ASSERT_EQ(madvise(ptr2, page_size, MADV_GUARD_INSTALL), 0);
1579 }
1580
1581 /* Now page it out. */
1582 ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_PAGEOUT), 0);
1583
1584 /* Now make sure pages are as expected. */
1585 for (i = 0; i < 10; i++) {
1586 char *chrp = &ptr[i * page_size];
1587
1588 if (i % 2 == 0) {
1589 bool result = try_read_write_buf(chrp);
1590
1591 ASSERT_FALSE(result);
1592 } else {
1593 ASSERT_EQ(*chrp, 'a' + i);
1594 }
1595 }
1596
1597 /* Now remove guard pages. */
1598 ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_GUARD_REMOVE), 0);
1599
1600 /* Now make sure all data is as expected. */
1601 if (!check_pattern(ptr, 10, page_size))
1602 ASSERT_TRUE(false);
1603
1604 ASSERT_EQ(munmap(ptr, 10 * page_size), 0);
1605}
1606
1607/*
1608 * Check that file-backed mappings implement guard regions with MAP_PRIVATE
1609 * correctly.
1610 */
1611TEST_F(guard_regions, map_private)
1612{
1613 const unsigned long page_size = self->page_size;
1614 char *ptr_shared, *ptr_private;
1615 int i;
1616
1617 if (variant->backing == ANON_BACKED)
1618 SKIP(return, "MAP_PRIVATE test specific to file-backed");
1619
1620 ptr_shared = mmap_(self, variant, NULL, 10 * page_size, PROT_READ | PROT_WRITE, 0, 0);
1621 ASSERT_NE(ptr_shared, MAP_FAILED);
1622
1623 /* Manually mmap(), do not use mmap_() wrapper so we can force MAP_PRIVATE. */
1624 ptr_private = mmap(NULL, 10 * page_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, self->fd, 0);
1625 ASSERT_NE(ptr_private, MAP_FAILED);
1626
1627 /* Set pattern in shared mapping. */
1628 set_pattern(ptr_shared, 10, page_size);
1629
1630 /* Install guard regions in every other page in the shared mapping. */
1631 for (i = 0; i < 10; i += 2) {
1632 char *ptr = &ptr_shared[i * page_size];
1633
1634 ASSERT_EQ(madvise(ptr, page_size, MADV_GUARD_INSTALL), 0);
1635 }
1636
1637 for (i = 0; i < 10; i++) {
1638 /* Every even shared page should be guarded. */
1639 ASSERT_EQ(try_read_buf(&ptr_shared[i * page_size]), i % 2 != 0);
1640 /* Private mappings should always be readable. */
1641 ASSERT_TRUE(try_read_buf(&ptr_private[i * page_size]));
1642 }
1643
1644 /* Install guard regions in every other page in the private mapping. */
1645 for (i = 0; i < 10; i += 2) {
1646 char *ptr = &ptr_private[i * page_size];
1647
1648 ASSERT_EQ(madvise(ptr, page_size, MADV_GUARD_INSTALL), 0);
1649 }
1650
1651 for (i = 0; i < 10; i++) {
1652 /* Every even shared page should be guarded. */
1653 ASSERT_EQ(try_read_buf(&ptr_shared[i * page_size]), i % 2 != 0);
1654 /* Every odd private page should be guarded. */
1655 ASSERT_EQ(try_read_buf(&ptr_private[i * page_size]), i % 2 != 0);
1656 }
1657
1658 /* Remove guard regions from shared mapping. */
1659 ASSERT_EQ(madvise(ptr_shared, 10 * page_size, MADV_GUARD_REMOVE), 0);
1660
1661 for (i = 0; i < 10; i++) {
1662 /* Shared mappings should always be readable. */
1663 ASSERT_TRUE(try_read_buf(&ptr_shared[i * page_size]));
1664 /* Every even private page should be guarded. */
1665 ASSERT_EQ(try_read_buf(&ptr_private[i * page_size]), i % 2 != 0);
1666 }
1667
1668 /* Remove guard regions from private mapping. */
1669 ASSERT_EQ(madvise(ptr_private, 10 * page_size, MADV_GUARD_REMOVE), 0);
1670
1671 for (i = 0; i < 10; i++) {
1672 /* Shared mappings should always be readable. */
1673 ASSERT_TRUE(try_read_buf(&ptr_shared[i * page_size]));
1674 /* Private mappings should always be readable. */
1675 ASSERT_TRUE(try_read_buf(&ptr_private[i * page_size]));
1676 }
1677
1678 /* Ensure patterns are intact. */
1679 ASSERT_TRUE(check_pattern(ptr_shared, 10, page_size));
1680 ASSERT_TRUE(check_pattern(ptr_private, 10, page_size));
1681
1682 /* Now write out every other page to MAP_PRIVATE. */
1683 for (i = 0; i < 10; i += 2) {
1684 char *ptr = &ptr_private[i * page_size];
1685
1686 memset(ptr, 'a' + i, page_size);
1687 }
1688
1689 /*
1690 * At this point the mapping is:
1691 *
1692 * 0123456789
1693 * SPSPSPSPSP
1694 *
1695 * Where S = shared, P = private mappings.
1696 */
1697
1698 /* Now mark the beginning of the mapping guarded. */
1699 ASSERT_EQ(madvise(ptr_private, 5 * page_size, MADV_GUARD_INSTALL), 0);
1700
1701 /*
1702 * This renders the mapping:
1703 *
1704 * 0123456789
1705 * xxxxxPSPSP
1706 */
1707
1708 for (i = 0; i < 10; i++) {
1709 char *ptr = &ptr_private[i * page_size];
1710
1711 /* Ensure guard regions as expected. */
1712 ASSERT_EQ(try_read_buf(ptr), i >= 5);
1713 /* The shared mapping should always succeed. */
1714 ASSERT_TRUE(try_read_buf(&ptr_shared[i * page_size]));
1715 }
1716
1717 /* Remove the guard regions altogether. */
1718 ASSERT_EQ(madvise(ptr_private, 10 * page_size, MADV_GUARD_REMOVE), 0);
1719
1720 /*
1721 *
1722 * We now expect the mapping to be:
1723 *
1724 * 0123456789
1725 * SSSSSPSPSP
1726 *
1727 * As we removed guard regions, the private pages from the first 5 will
1728 * have been zapped, so on fault will reestablish the shared mapping.
1729 */
1730
1731 for (i = 0; i < 10; i++) {
1732 char *ptr = &ptr_private[i * page_size];
1733
1734 /*
1735 * Assert that shared mappings in the MAP_PRIVATE mapping match
1736 * the shared mapping.
1737 */
1738 if (i < 5 || i % 2 == 0) {
1739 char *ptr_s = &ptr_shared[i * page_size];
1740
1741 ASSERT_EQ(memcmp(ptr, ptr_s, page_size), 0);
1742 continue;
1743 }
1744
1745 /* Everything else is a private mapping. */
1746 ASSERT_TRUE(is_buf_eq(ptr, page_size, 'a' + i));
1747 }
1748
1749 ASSERT_EQ(munmap(ptr_shared, 10 * page_size), 0);
1750 ASSERT_EQ(munmap(ptr_private, 10 * page_size), 0);
1751}
1752
1753/* Test that guard regions established over a read-only mapping function correctly. */
1754TEST_F(guard_regions, readonly_file)
1755{
1756 const unsigned long page_size = self->page_size;
1757 char *ptr;
1758 int i;
1759
1760 if (variant->backing != LOCAL_FILE_BACKED)
1761 SKIP(return, "Read-only test specific to file-backed");
1762
1763 /* Map shared so we can populate with pattern, populate it, unmap. */
1764 ptr = mmap_(self, variant, NULL, 10 * page_size,
1765 PROT_READ | PROT_WRITE, 0, 0);
1766 ASSERT_NE(ptr, MAP_FAILED);
1767 set_pattern(ptr, 10, page_size);
1768 ASSERT_EQ(munmap(ptr, 10 * page_size), 0);
1769 /* Close the fd so we can re-open read-only. */
1770 ASSERT_EQ(close(self->fd), 0);
1771
1772 /* Re-open read-only. */
1773 self->fd = open(self->path, O_RDONLY);
1774 ASSERT_NE(self->fd, -1);
1775 /* Re-map read-only. */
1776 ptr = mmap_(self, variant, NULL, 10 * page_size, PROT_READ, 0, 0);
1777 ASSERT_NE(ptr, MAP_FAILED);
1778
1779 /* Mark every other page guarded. */
1780 for (i = 0; i < 10; i += 2) {
1781 char *ptr_pg = &ptr[i * page_size];
1782
1783 ASSERT_EQ(madvise(ptr_pg, page_size, MADV_GUARD_INSTALL), 0);
1784 }
1785
1786 /* Assert that the guard regions are in place.*/
1787 for (i = 0; i < 10; i++) {
1788 char *ptr_pg = &ptr[i * page_size];
1789
1790 ASSERT_EQ(try_read_buf(ptr_pg), i % 2 != 0);
1791 }
1792
1793 /* Remove guard regions. */
1794 ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_GUARD_REMOVE), 0);
1795
1796 /* Ensure the data is as expected. */
1797 ASSERT_TRUE(check_pattern(ptr, 10, page_size));
1798
1799 ASSERT_EQ(munmap(ptr, 10 * page_size), 0);
1800}
1801
1802TEST_F(guard_regions, fault_around)
1803{
1804 const unsigned long page_size = self->page_size;
1805 char *ptr;
1806 int i;
1807
1808 if (variant->backing == ANON_BACKED)
1809 SKIP(return, "Fault-around test specific to file-backed");
1810
1811 ptr = mmap_(self, variant, NULL, 10 * page_size,
1812 PROT_READ | PROT_WRITE, 0, 0);
1813 ASSERT_NE(ptr, MAP_FAILED);
1814
1815 /* Establish a pattern in the backing file. */
1816 set_pattern(ptr, 10, page_size);
1817
1818 /*
1819 * Now drop it from the page cache so we get major faults when next we
1820 * map it.
1821 */
1822 ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_PAGEOUT), 0);
1823
1824 /* Unmap and remap 'to be sure'. */
1825 ASSERT_EQ(munmap(ptr, 10 * page_size), 0);
1826 ptr = mmap_(self, variant, NULL, 10 * page_size,
1827 PROT_READ | PROT_WRITE, 0, 0);
1828 ASSERT_NE(ptr, MAP_FAILED);
1829
1830 /* Now make every even page guarded. */
1831 for (i = 0; i < 10; i += 2) {
1832 char *ptr_p = &ptr[i * page_size];
1833
1834 ASSERT_EQ(madvise(ptr_p, page_size, MADV_GUARD_INSTALL), 0);
1835 }
1836
1837 /* Now fault in every odd page. This should trigger fault-around. */
1838 for (i = 1; i < 10; i += 2) {
1839 char *ptr_p = &ptr[i * page_size];
1840
1841 ASSERT_TRUE(try_read_buf(ptr_p));
1842 }
1843
1844 /* Finally, ensure that guard regions are intact as expected. */
1845 for (i = 0; i < 10; i++) {
1846 char *ptr_p = &ptr[i * page_size];
1847
1848 ASSERT_EQ(try_read_buf(ptr_p), i % 2 != 0);
1849 }
1850
1851 ASSERT_EQ(munmap(ptr, 10 * page_size), 0);
1852}
1853
1854TEST_F(guard_regions, truncation)
1855{
1856 const unsigned long page_size = self->page_size;
1857 char *ptr;
1858 int i;
1859
1860 if (variant->backing == ANON_BACKED)
1861 SKIP(return, "Truncation test specific to file-backed");
1862
1863 ptr = mmap_(self, variant, NULL, 10 * page_size,
1864 PROT_READ | PROT_WRITE, 0, 0);
1865 ASSERT_NE(ptr, MAP_FAILED);
1866
1867 /*
1868 * Establish a pattern in the backing file, just so there is data
1869 * there.
1870 */
1871 set_pattern(ptr, 10, page_size);
1872
1873 /* Now make every even page guarded. */
1874 for (i = 0; i < 10; i += 2) {
1875 char *ptr_p = &ptr[i * page_size];
1876
1877 ASSERT_EQ(madvise(ptr_p, page_size, MADV_GUARD_INSTALL), 0);
1878 }
1879
1880 /* Now assert things are as expected. */
1881 for (i = 0; i < 10; i++) {
1882 char *ptr_p = &ptr[i * page_size];
1883
1884 ASSERT_EQ(try_read_write_buf(ptr_p), i % 2 != 0);
1885 }
1886
1887 /* Now truncate to actually used size (initialised to 100). */
1888 ASSERT_EQ(ftruncate(self->fd, 10 * page_size), 0);
1889
1890 /* Here the guard regions will remain intact. */
1891 for (i = 0; i < 10; i++) {
1892 char *ptr_p = &ptr[i * page_size];
1893
1894 ASSERT_EQ(try_read_write_buf(ptr_p), i % 2 != 0);
1895 }
1896
1897 /* Now truncate to half the size, then truncate again to the full size. */
1898 ASSERT_EQ(ftruncate(self->fd, 5 * page_size), 0);
1899 ASSERT_EQ(ftruncate(self->fd, 10 * page_size), 0);
1900
1901 /* Again, guard pages will remain intact. */
1902 for (i = 0; i < 10; i++) {
1903 char *ptr_p = &ptr[i * page_size];
1904
1905 ASSERT_EQ(try_read_write_buf(ptr_p), i % 2 != 0);
1906 }
1907
1908 ASSERT_EQ(munmap(ptr, 10 * page_size), 0);
1909}
1910
1911TEST_F(guard_regions, hole_punch)
1912{
1913 const unsigned long page_size = self->page_size;
1914 char *ptr;
1915 int i;
1916
1917 if (variant->backing == ANON_BACKED)
1918 SKIP(return, "Truncation test specific to file-backed");
1919
1920 /* Establish pattern in mapping. */
1921 ptr = mmap_(self, variant, NULL, 10 * page_size,
1922 PROT_READ | PROT_WRITE, 0, 0);
1923 ASSERT_NE(ptr, MAP_FAILED);
1924 set_pattern(ptr, 10, page_size);
1925
1926 /* Install a guard region in the middle of the mapping. */
1927 ASSERT_EQ(madvise(&ptr[3 * page_size], 4 * page_size,
1928 MADV_GUARD_INSTALL), 0);
1929
1930 /*
1931 * The buffer will now be:
1932 *
1933 * 0123456789
1934 * ***xxxx***
1935 *
1936 * Where * is data and x is the guard region.
1937 */
1938
1939 /* Ensure established. */
1940 for (i = 0; i < 10; i++) {
1941 char *ptr_p = &ptr[i * page_size];
1942
1943 ASSERT_EQ(try_read_buf(ptr_p), i < 3 || i >= 7);
1944 }
1945
1946 /* Now hole punch the guarded region. */
1947 ASSERT_EQ(madvise(&ptr[3 * page_size], 4 * page_size,
1948 MADV_REMOVE), 0);
1949
1950 /* Ensure guard regions remain. */
1951 for (i = 0; i < 10; i++) {
1952 char *ptr_p = &ptr[i * page_size];
1953
1954 ASSERT_EQ(try_read_buf(ptr_p), i < 3 || i >= 7);
1955 }
1956
1957 /* Now remove guard region throughout. */
1958 ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_GUARD_REMOVE), 0);
1959
1960 /* Check that the pattern exists in non-hole punched region. */
1961 ASSERT_TRUE(check_pattern(ptr, 3, page_size));
1962 /* Check that hole punched region is zeroed. */
1963 ASSERT_TRUE(is_buf_eq(&ptr[3 * page_size], 4 * page_size, '\0'));
1964 /* Check that the pattern exists in the remainder of the file. */
1965 ASSERT_TRUE(check_pattern_offset(ptr, 3, page_size, 7));
1966
1967 ASSERT_EQ(munmap(ptr, 10 * page_size), 0);
1968}
1969
1970/*
1971 * Ensure that a memfd works correctly with guard regions, that we can write
1972 * seal it then open the mapping read-only and still establish guard regions
1973 * within, remove those guard regions and have everything work correctly.
1974 */
1975TEST_F(guard_regions, memfd_write_seal)
1976{
1977 const unsigned long page_size = self->page_size;
1978 char *ptr;
1979 int i;
1980
1981 if (variant->backing != SHMEM_BACKED)
1982 SKIP(return, "memfd write seal test specific to shmem");
1983
1984 /* OK, we need a memfd, so close existing one. */
1985 ASSERT_EQ(close(self->fd), 0);
1986
1987 /* Create and truncate memfd. */
1988 self->fd = memfd_create("guard_regions_memfd_seals_test",
1989 MFD_ALLOW_SEALING);
1990 ASSERT_NE(self->fd, -1);
1991 ASSERT_EQ(ftruncate(self->fd, 10 * page_size), 0);
1992
1993 /* Map, set pattern, unmap. */
1994 ptr = mmap_(self, variant, NULL, 10 * page_size, PROT_READ | PROT_WRITE, 0, 0);
1995 ASSERT_NE(ptr, MAP_FAILED);
1996 set_pattern(ptr, 10, page_size);
1997 ASSERT_EQ(munmap(ptr, 10 * page_size), 0);
1998
1999 /* Write-seal the memfd. */
2000 ASSERT_EQ(fcntl(self->fd, F_ADD_SEALS, F_SEAL_WRITE), 0);
2001
2002 /* Now map the memfd readonly. */
2003 ptr = mmap_(self, variant, NULL, 10 * page_size, PROT_READ, 0, 0);
2004 ASSERT_NE(ptr, MAP_FAILED);
2005
2006 /* Ensure pattern is as expected. */
2007 ASSERT_TRUE(check_pattern(ptr, 10, page_size));
2008
2009 /* Now make every even page guarded. */
2010 for (i = 0; i < 10; i += 2) {
2011 char *ptr_p = &ptr[i * page_size];
2012
2013 ASSERT_EQ(madvise(ptr_p, page_size, MADV_GUARD_INSTALL), 0);
2014 }
2015
2016 /* Now assert things are as expected. */
2017 for (i = 0; i < 10; i++) {
2018 char *ptr_p = &ptr[i * page_size];
2019
2020 ASSERT_EQ(try_read_buf(ptr_p), i % 2 != 0);
2021 }
2022
2023 /* Now remove guard regions. */
2024 ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_GUARD_REMOVE), 0);
2025
2026 /* Ensure pattern is as expected. */
2027 ASSERT_TRUE(check_pattern(ptr, 10, page_size));
2028
2029 /* Ensure write seal intact. */
2030 for (i = 0; i < 10; i++) {
2031 char *ptr_p = &ptr[i * page_size];
2032
2033 ASSERT_FALSE(try_write_buf(ptr_p));
2034 }
2035
2036 ASSERT_EQ(munmap(ptr, 10 * page_size), 0);
2037}
2038
2039
2040/*
2041 * Since we are now permitted to establish guard regions in read-only anonymous
2042 * mappings, for the sake of thoroughness, though it probably has no practical
2043 * use, test that guard regions function with a mapping to the anonymous zero
2044 * page.
2045 */
2046TEST_F(guard_regions, anon_zeropage)
2047{
2048 const unsigned long page_size = self->page_size;
2049 char *ptr;
2050 int i;
2051
2052 if (!is_anon_backed(variant))
2053 SKIP(return, "anon zero page test specific to anon/shmem");
2054
2055 /* Obtain a read-only i.e. anon zero page mapping. */
2056 ptr = mmap_(self, variant, NULL, 10 * page_size, PROT_READ, 0, 0);
2057 ASSERT_NE(ptr, MAP_FAILED);
2058
2059 /* Now make every even page guarded. */
2060 for (i = 0; i < 10; i += 2) {
2061 char *ptr_p = &ptr[i * page_size];
2062
2063 ASSERT_EQ(madvise(ptr_p, page_size, MADV_GUARD_INSTALL), 0);
2064 }
2065
2066 /* Now assert things are as expected. */
2067 for (i = 0; i < 10; i++) {
2068 char *ptr_p = &ptr[i * page_size];
2069
2070 ASSERT_EQ(try_read_buf(ptr_p), i % 2 != 0);
2071 }
2072
2073 /* Now remove all guard regions. */
2074 ASSERT_EQ(madvise(ptr, 10 * page_size, MADV_GUARD_REMOVE), 0);
2075
2076 /* Now assert things are as expected. */
2077 for (i = 0; i < 10; i++) {
2078 char *ptr_p = &ptr[i * page_size];
2079
2080 ASSERT_TRUE(try_read_buf(ptr_p));
2081 }
2082
2083 /* Ensure zero page...*/
2084 ASSERT_TRUE(is_buf_eq(ptr, 10 * page_size, '\0'));
2085
2086 ASSERT_EQ(munmap(ptr, 10 * page_size), 0);
2087}
2088
2089/*
2090 * Assert that /proc/$pid/pagemap correctly identifies guard region ranges.
2091 */
2092TEST_F(guard_regions, pagemap)
2093{
2094 const unsigned long page_size = self->page_size;
2095 int proc_fd;
2096 char *ptr;
2097 int i;
2098
2099 proc_fd = open("/proc/self/pagemap", O_RDONLY);
2100 ASSERT_NE(proc_fd, -1);
2101
2102 ptr = mmap_(self, variant, NULL, 10 * page_size,
2103 PROT_READ | PROT_WRITE, 0, 0);
2104 ASSERT_NE(ptr, MAP_FAILED);
2105
2106 /* Read from pagemap, and assert no guard regions are detected. */
2107 for (i = 0; i < 10; i++) {
2108 char *ptr_p = &ptr[i * page_size];
2109 unsigned long entry = pagemap_get_entry(proc_fd, ptr_p);
2110 unsigned long masked = entry & PM_GUARD_REGION;
2111
2112 ASSERT_EQ(masked, 0);
2113 }
2114
2115 /* Install a guard region in every other page. */
2116 for (i = 0; i < 10; i += 2) {
2117 char *ptr_p = &ptr[i * page_size];
2118
2119 ASSERT_EQ(madvise(ptr_p, page_size, MADV_GUARD_INSTALL), 0);
2120 }
2121
2122 /* Re-read from pagemap, and assert guard regions are detected. */
2123 for (i = 0; i < 10; i++) {
2124 char *ptr_p = &ptr[i * page_size];
2125 unsigned long entry = pagemap_get_entry(proc_fd, ptr_p);
2126 unsigned long masked = entry & PM_GUARD_REGION;
2127
2128 ASSERT_EQ(masked, i % 2 == 0 ? PM_GUARD_REGION : 0);
2129 }
2130
2131 ASSERT_EQ(close(proc_fd), 0);
2132 ASSERT_EQ(munmap(ptr, 10 * page_size), 0);
2133}
2134
2135/*
2136 * Assert that PAGEMAP_SCAN correctly reports guard region ranges.
2137 */
2138TEST_F(guard_regions, pagemap_scan)
2139{
2140 const unsigned long page_size = self->page_size;
2141 struct page_region pm_regs[10];
2142 struct pm_scan_arg pm_scan_args = {
2143 .size = sizeof(struct pm_scan_arg),
2144 .category_anyof_mask = PAGE_IS_GUARD,
2145 .return_mask = PAGE_IS_GUARD,
2146 .vec = (long)&pm_regs,
2147 .vec_len = ARRAY_SIZE(pm_regs),
2148 };
2149 int proc_fd, i;
2150 char *ptr;
2151
2152 proc_fd = open("/proc/self/pagemap", O_RDONLY);
2153 ASSERT_NE(proc_fd, -1);
2154
2155 ptr = mmap_(self, variant, NULL, 10 * page_size,
2156 PROT_READ | PROT_WRITE, 0, 0);
2157 ASSERT_NE(ptr, MAP_FAILED);
2158
2159 pm_scan_args.start = (long)ptr;
2160 pm_scan_args.end = (long)ptr + 10 * page_size;
2161 ASSERT_EQ(ioctl(proc_fd, PAGEMAP_SCAN, &pm_scan_args), 0);
2162 ASSERT_EQ(pm_scan_args.walk_end, (long)ptr + 10 * page_size);
2163
2164 /* Install a guard region in every other page. */
2165 for (i = 0; i < 10; i += 2) {
2166 char *ptr_p = &ptr[i * page_size];
2167
2168 ASSERT_EQ(syscall(__NR_madvise, ptr_p, page_size, MADV_GUARD_INSTALL), 0);
2169 }
2170
2171 /*
2172 * Assert ioctl() returns the count of located regions, where each
2173 * region spans every other page within the range of 10 pages.
2174 */
2175 ASSERT_EQ(ioctl(proc_fd, PAGEMAP_SCAN, &pm_scan_args), 5);
2176 ASSERT_EQ(pm_scan_args.walk_end, (long)ptr + 10 * page_size);
2177
2178 /* Re-read from pagemap, and assert guard regions are detected. */
2179 for (i = 0; i < 5; i++) {
2180 long ptr_p = (long)&ptr[2 * i * page_size];
2181
2182 ASSERT_EQ(pm_regs[i].start, ptr_p);
2183 ASSERT_EQ(pm_regs[i].end, ptr_p + page_size);
2184 ASSERT_EQ(pm_regs[i].categories, PAGE_IS_GUARD);
2185 }
2186
2187 ASSERT_EQ(close(proc_fd), 0);
2188 ASSERT_EQ(munmap(ptr, 10 * page_size), 0);
2189}
2190
2191TEST_F(guard_regions, collapse)
2192{
2193 const unsigned long page_size = self->page_size;
2194 const unsigned long size = 2 * HPAGE_SIZE;
2195 const unsigned long num_pages = size / page_size;
2196 char *ptr;
2197 int i;
2198
2199 if (!thp_available())
2200 SKIP(return, "Transparent Hugepages not available\n");
2201
2202 /* Need file to be correct size for tests for non-anon. */
2203 if (variant->backing != ANON_BACKED)
2204 ASSERT_EQ(ftruncate(self->fd, size), 0);
2205
2206 /*
2207 * We must close and re-open local-file backed as read-only for
2208 * CONFIG_READ_ONLY_THP_FOR_FS to work.
2209 */
2210 if (variant->backing == LOCAL_FILE_BACKED) {
2211 ASSERT_EQ(close(self->fd), 0);
2212
2213 self->fd = open(self->path, O_RDONLY);
2214 ASSERT_GE(self->fd, 0);
2215 }
2216
2217 ptr = mmap_(self, variant, NULL, size, PROT_READ, 0, 0);
2218 ASSERT_NE(ptr, MAP_FAILED);
2219
2220 /* Prevent being faulted-in as huge. */
2221 ASSERT_EQ(madvise(ptr, size, MADV_NOHUGEPAGE), 0);
2222 /* Fault in. */
2223 ASSERT_EQ(madvise(ptr, size, MADV_POPULATE_READ), 0);
2224
2225 /* Install guard regions in ever other page. */
2226 for (i = 0; i < num_pages; i += 2) {
2227 char *ptr_page = &ptr[i * page_size];
2228
2229 ASSERT_EQ(madvise(ptr_page, page_size, MADV_GUARD_INSTALL), 0);
2230 /* Accesses should now fail. */
2231 ASSERT_FALSE(try_read_buf(ptr_page));
2232 }
2233
2234 /* Allow huge page throughout region. */
2235 ASSERT_EQ(madvise(ptr, size, MADV_HUGEPAGE), 0);
2236
2237 /*
2238 * Now collapse the entire region. This should fail in all cases.
2239 *
2240 * The madvise() call will also fail if CONFIG_READ_ONLY_THP_FOR_FS is
2241 * not set for the local file case, but we can't differentiate whether
2242 * this occurred or if the collapse was rightly rejected.
2243 */
2244 EXPECT_NE(madvise(ptr, size, MADV_COLLAPSE), 0);
2245
2246 /*
2247 * If we introduce a bug that causes the collapse to succeed, gather
2248 * data on whether guard regions are at least preserved. The test will
2249 * fail at this point in any case.
2250 */
2251 for (i = 0; i < num_pages; i += 2) {
2252 char *ptr_page = &ptr[i * page_size];
2253
2254 /* Accesses should still fail. */
2255 ASSERT_FALSE(try_read_buf(ptr_page));
2256 }
2257}
2258
2259TEST_F(guard_regions, smaps)
2260{
2261 const unsigned long page_size = self->page_size;
2262 struct procmap_fd procmap;
2263 char *ptr, *ptr2;
2264 int i;
2265
2266 /* Map a region. */
2267 ptr = mmap_(self, variant, NULL, 10 * page_size, PROT_READ | PROT_WRITE, 0, 0);
2268 ASSERT_NE(ptr, MAP_FAILED);
2269
2270 /* We shouldn't yet see a guard flag. */
2271 ASSERT_FALSE(check_vmflag_guard(ptr));
2272
2273 /* Install a single guard region. */
2274 ASSERT_EQ(madvise(ptr, page_size, MADV_GUARD_INSTALL), 0);
2275
2276 /* Now we should see a guard flag. */
2277 ASSERT_TRUE(check_vmflag_guard(ptr));
2278
2279 /*
2280 * Removing the guard region should not change things because we simply
2281 * cannot accurately track whether a given VMA has had all of its guard
2282 * regions removed.
2283 */
2284 ASSERT_EQ(madvise(ptr, page_size, MADV_GUARD_REMOVE), 0);
2285 ASSERT_TRUE(check_vmflag_guard(ptr));
2286
2287 /* Install guard regions throughout. */
2288 for (i = 0; i < 10; i++) {
2289 ASSERT_EQ(madvise(&ptr[i * page_size], page_size, MADV_GUARD_INSTALL), 0);
2290 /* We should always see the guard region flag. */
2291 ASSERT_TRUE(check_vmflag_guard(ptr));
2292 }
2293
2294 /* Split into two VMAs. */
2295 ASSERT_EQ(munmap(&ptr[4 * page_size], page_size), 0);
2296
2297 /* Both VMAs should have the guard flag set. */
2298 ASSERT_TRUE(check_vmflag_guard(ptr));
2299 ASSERT_TRUE(check_vmflag_guard(&ptr[5 * page_size]));
2300
2301 /*
2302 * If the local file system is unable to merge VMAs due to having
2303 * unusual characteristics, there is no point in asserting merge
2304 * behaviour.
2305 */
2306 if (!local_fs_has_sane_mmap(self, variant)) {
2307 TH_LOG("local filesystem does not support sane merging skipping merge test");
2308 return;
2309 }
2310
2311 /* Map a fresh VMA between the two split VMAs. */
2312 ptr2 = mmap_(self, variant, &ptr[4 * page_size], page_size,
2313 PROT_READ | PROT_WRITE, MAP_FIXED, 4 * page_size);
2314 ASSERT_NE(ptr2, MAP_FAILED);
2315
2316 /*
2317 * Check the procmap to ensure that this VMA merged with the adjacent
2318 * two. The guard region flag is 'sticky' so should not preclude
2319 * merging.
2320 */
2321 ASSERT_EQ(open_self_procmap(&procmap), 0);
2322 ASSERT_TRUE(find_vma_procmap(&procmap, ptr));
2323 ASSERT_EQ(procmap.query.vma_start, (unsigned long)ptr);
2324 ASSERT_EQ(procmap.query.vma_end, (unsigned long)ptr + 10 * page_size);
2325 ASSERT_EQ(close_procmap(&procmap), 0);
2326 /* And, of course, this VMA should have the guard flag set. */
2327 ASSERT_TRUE(check_vmflag_guard(ptr));
2328}
2329
2330TEST_HARNESS_MAIN