tools/testing/selftests/memfd/memfd_test.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #define _GNU_SOURCE
   3 #define __EXPORTED_HEADERS__
   4
   5 #include <errno.h>
   6 #include <inttypes.h>
   7 #include <limits.h>
   8 #include <linux/falloc.h>
   9 #include <fcntl.h>
  10 #include <linux/memfd.h>
  11 #include <sched.h>
  12 #include <stdio.h>
  13 #include <stdlib.h>
  14 #include <signal.h>
  15 #include <string.h>
  16 #include <sys/mman.h>
  17 #include <sys/stat.h>
  18 #include <sys/syscall.h>
  19 #include <sys/wait.h>
  20 #include <unistd.h>
  21
  22 #include "common.h"
  23
  24 #define MEMFD_STR       "memfd:"
  25 #define MEMFD_HUGE_STR  "memfd-hugetlb:"
  26 #define SHARED_FT_STR   "(shared file-table)"
  27
  28 #define MFD_DEF_SIZE 8192
  29 #define STACK_SIZE 65536
  30
  31 /*
  32  * Default is not to test hugetlbfs
  33  */
  34 static size_t mfd_def_size = MFD_DEF_SIZE;
  35 static const char *memfd_str = MEMFD_STR;
  36
  37 static int mfd_assert_new(const char *name, loff_t sz, unsigned int flags)
  38 {
  39         int r, fd;
  40
  41         fd = sys_memfd_create(name, flags);
  42         if (fd < 0) {
  43                 printf("memfd_create(\"%s\", %u) failed: %m\n",
  44                        name, flags);
  45                 abort();
  46         }
  47
  48         r = ftruncate(fd, sz);
  49         if (r < 0) {
  50                 printf("ftruncate(%llu) failed: %m\n", (unsigned long long)sz);
  51                 abort();
  52         }
  53
  54         return fd;
  55 }
  56
  57 static int mfd_assert_reopen_fd(int fd_in)
  58 {
  59         int fd;
  60         char path[100];
  61
  62         sprintf(path, "/proc/self/fd/%d", fd_in);
  63
  64         fd = open(path, O_RDWR);
  65         if (fd < 0) {
  66                 printf("re-open of existing fd %d failed\n", fd_in);
  67                 abort();
  68         }
  69
  70         return fd;
  71 }
  72
  73 static void mfd_fail_new(const char *name, unsigned int flags)
  74 {
  75         int r;
  76
  77         r = sys_memfd_create(name, flags);
  78         if (r >= 0) {
  79                 printf("memfd_create(\"%s\", %u) succeeded, but failure expected\n",
  80                        name, flags);
  81                 close(r);
  82                 abort();
  83         }
  84 }
  85
  86 static unsigned int mfd_assert_get_seals(int fd)
  87 {
  88         int r;
  89
  90         r = fcntl(fd, F_GET_SEALS);
  91         if (r < 0) {
  92                 printf("GET_SEALS(%d) failed: %m\n", fd);
  93                 abort();
  94         }
  95
  96         return (unsigned int)r;
  97 }
  98
  99 static void mfd_assert_has_seals(int fd, unsigned int seals)
 100 {
 101         unsigned int s;
 102
 103         s = mfd_assert_get_seals(fd);
 104         if (s != seals) {
 105                 printf("%u != %u = GET_SEALS(%d)\n", seals, s, fd);
 106                 abort();
 107         }
 108 }
 109
 110 static void mfd_assert_add_seals(int fd, unsigned int seals)
 111 {
 112         int r;
 113         unsigned int s;
 114
 115         s = mfd_assert_get_seals(fd);
 116         r = fcntl(fd, F_ADD_SEALS, seals);
 117         if (r < 0) {
 118                 printf("ADD_SEALS(%d, %u -> %u) failed: %m\n", fd, s, seals);
 119                 abort();
 120         }
 121 }
 122
 123 static void mfd_fail_add_seals(int fd, unsigned int seals)
 124 {
 125         int r;
 126         unsigned int s;
 127
 128         r = fcntl(fd, F_GET_SEALS);
 129         if (r < 0)
 130                 s = 0;
 131         else
 132                 s = (unsigned int)r;
 133
 134         r = fcntl(fd, F_ADD_SEALS, seals);
 135         if (r >= 0) {
 136                 printf("ADD_SEALS(%d, %u -> %u) didn't fail as expected\n",
 137                                 fd, s, seals);
 138                 abort();
 139         }
 140 }
 141
 142 static void mfd_assert_size(int fd, size_t size)
 143 {
 144         struct stat st;
 145         int r;
 146
 147         r = fstat(fd, &st);
 148         if (r < 0) {
 149                 printf("fstat(%d) failed: %m\n", fd);
 150                 abort();
 151         } else if (st.st_size != size) {
 152                 printf("wrong file size %lld, but expected %lld\n",
 153                        (long long)st.st_size, (long long)size);
 154                 abort();
 155         }
 156 }
 157
 158 static int mfd_assert_dup(int fd)
 159 {
 160         int r;
 161
 162         r = dup(fd);
 163         if (r < 0) {
 164                 printf("dup(%d) failed: %m\n", fd);
 165                 abort();
 166         }
 167
 168         return r;
 169 }
 170
 171 static void *mfd_assert_mmap_shared(int fd)
 172 {
 173         void *p;
 174
 175         p = mmap(NULL,
 176                  mfd_def_size,
 177                  PROT_READ | PROT_WRITE,
 178                  MAP_SHARED,
 179                  fd,
 180                  0);
 181         if (p == MAP_FAILED) {
 182                 printf("mmap() failed: %m\n");
 183                 abort();
 184         }
 185
 186         return p;
 187 }
 188
 189 static void *mfd_assert_mmap_private(int fd)
 190 {
 191         void *p;
 192
 193         p = mmap(NULL,
 194                  mfd_def_size,
 195                  PROT_READ,
 196                  MAP_PRIVATE,
 197                  fd,
 198                  0);
 199         if (p == MAP_FAILED) {
 200                 printf("mmap() failed: %m\n");
 201                 abort();
 202         }
 203
 204         return p;
 205 }
 206
 207 static int mfd_assert_open(int fd, int flags, mode_t mode)
 208 {
 209         char buf[512];
 210         int r;
 211
 212         sprintf(buf, "/proc/self/fd/%d", fd);
 213         r = open(buf, flags, mode);
 214         if (r < 0) {
 215                 printf("open(%s) failed: %m\n", buf);
 216                 abort();
 217         }
 218
 219         return r;
 220 }
 221
 222 static void mfd_fail_open(int fd, int flags, mode_t mode)
 223 {
 224         char buf[512];
 225         int r;
 226
 227         sprintf(buf, "/proc/self/fd/%d", fd);
 228         r = open(buf, flags, mode);
 229         if (r >= 0) {
 230                 printf("open(%s) didn't fail as expected\n", buf);
 231                 abort();
 232         }
 233 }
 234
 235 static void mfd_assert_read(int fd)
 236 {
 237         char buf[16];
 238         void *p;
 239         ssize_t l;
 240
 241         l = read(fd, buf, sizeof(buf));
 242         if (l != sizeof(buf)) {
 243                 printf("read() failed: %m\n");
 244                 abort();
 245         }
 246
 247         /* verify PROT_READ *is* allowed */
 248         p = mmap(NULL,
 249                  mfd_def_size,
 250                  PROT_READ,
 251                  MAP_PRIVATE,
 252                  fd,
 253                  0);
 254         if (p == MAP_FAILED) {
 255                 printf("mmap() failed: %m\n");
 256                 abort();
 257         }
 258         munmap(p, mfd_def_size);
 259
 260         /* verify MAP_PRIVATE is *always* allowed (even writable) */
 261         p = mmap(NULL,
 262                  mfd_def_size,
 263                  PROT_READ | PROT_WRITE,
 264                  MAP_PRIVATE,
 265                  fd,
 266                  0);
 267         if (p == MAP_FAILED) {
 268                 printf("mmap() failed: %m\n");
 269                 abort();
 270         }
 271         munmap(p, mfd_def_size);
 272 }
 273
 274 /* Test that PROT_READ + MAP_SHARED mappings work. */
 275 static void mfd_assert_read_shared(int fd)
 276 {
 277         void *p;
 278
 279         /* verify PROT_READ and MAP_SHARED *is* allowed */
 280         p = mmap(NULL,
 281                  mfd_def_size,
 282                  PROT_READ,
 283                  MAP_SHARED,
 284                  fd,
 285                  0);
 286         if (p == MAP_FAILED) {
 287                 printf("mmap() failed: %m\n");
 288                 abort();
 289         }
 290         munmap(p, mfd_def_size);
 291 }
 292
 293 static void mfd_assert_fork_private_write(int fd)
 294 {
 295         int *p;
 296         pid_t pid;
 297
 298         p = mmap(NULL,
 299                  mfd_def_size,
 300                  PROT_READ | PROT_WRITE,
 301                  MAP_PRIVATE,
 302                  fd,
 303                  0);
 304         if (p == MAP_FAILED) {
 305                 printf("mmap() failed: %m\n");
 306                 abort();
 307         }
 308
 309         p[0] = 22;
 310
 311         pid = fork();
 312         if (pid == 0) {
 313                 p[0] = 33;
 314                 exit(0);
 315         } else {
 316                 waitpid(pid, NULL, 0);
 317
 318                 if (p[0] != 22) {
 319                         printf("MAP_PRIVATE copy-on-write failed: %m\n");
 320                         abort();
 321                 }
 322         }
 323
 324         munmap(p, mfd_def_size);
 325 }
 326
 327 static void mfd_assert_write(int fd)
 328 {
 329         ssize_t l;
 330         void *p;
 331         int r;
 332
 333         /*
 334          * huegtlbfs does not support write, but we want to
 335          * verify everything else here.
 336          */
 337         if (!hugetlbfs_test) {
 338                 /* verify write() succeeds */
 339                 l = write(fd, "\0\0\0\0", 4);
 340                 if (l != 4) {
 341                         printf("write() failed: %m\n");
 342                         abort();
 343                 }
 344         }
 345
 346         /* verify PROT_READ | PROT_WRITE is allowed */
 347         p = mmap(NULL,
 348                  mfd_def_size,
 349                  PROT_READ | PROT_WRITE,
 350                  MAP_SHARED,
 351                  fd,
 352                  0);
 353         if (p == MAP_FAILED) {
 354                 printf("mmap() failed: %m\n");
 355                 abort();
 356         }
 357         *(char *)p = 0;
 358         munmap(p, mfd_def_size);
 359
 360         /* verify PROT_WRITE is allowed */
 361         p = mmap(NULL,
 362                  mfd_def_size,
 363                  PROT_WRITE,
 364                  MAP_SHARED,
 365                  fd,
 366                  0);
 367         if (p == MAP_FAILED) {
 368                 printf("mmap() failed: %m\n");
 369                 abort();
 370         }
 371         *(char *)p = 0;
 372         munmap(p, mfd_def_size);
 373
 374         /* verify PROT_READ with MAP_SHARED is allowed and a following
 375          * mprotect(PROT_WRITE) allows writing */
 376         p = mmap(NULL,
 377                  mfd_def_size,
 378                  PROT_READ,
 379                  MAP_SHARED,
 380                  fd,
 381                  0);
 382         if (p == MAP_FAILED) {
 383                 printf("mmap() failed: %m\n");
 384                 abort();
 385         }
 386
 387         r = mprotect(p, mfd_def_size, PROT_READ | PROT_WRITE);
 388         if (r < 0) {
 389                 printf("mprotect() failed: %m\n");
 390                 abort();
 391         }
 392
 393         *(char *)p = 0;
 394         munmap(p, mfd_def_size);
 395
 396         /* verify PUNCH_HOLE works */
 397         r = fallocate(fd,
 398                       FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
 399                       0,
 400                       mfd_def_size);
 401         if (r < 0) {
 402                 printf("fallocate(PUNCH_HOLE) failed: %m\n");
 403                 abort();
 404         }
 405 }
 406
 407 static void mfd_fail_write(int fd)
 408 {
 409         ssize_t l;
 410         void *p;
 411         int r;
 412
 413         /* verify write() fails */
 414         l = write(fd, "data", 4);
 415         if (l != -EPERM) {
 416                 printf("expected EPERM on write(), but got %d: %m\n", (int)l);
 417                 abort();
 418         }
 419
 420         /* verify PROT_READ | PROT_WRITE is not allowed */
 421         p = mmap(NULL,
 422                  mfd_def_size,
 423                  PROT_READ | PROT_WRITE,
 424                  MAP_SHARED,
 425                  fd,
 426                  0);
 427         if (p != MAP_FAILED) {
 428                 printf("mmap() didn't fail as expected\n");
 429                 abort();
 430         }
 431
 432         /* verify PROT_WRITE is not allowed */
 433         p = mmap(NULL,
 434                  mfd_def_size,
 435                  PROT_WRITE,
 436                  MAP_SHARED,
 437                  fd,
 438                  0);
 439         if (p != MAP_FAILED) {
 440                 printf("mmap() didn't fail as expected\n");
 441                 abort();
 442         }
 443
 444         /* Verify PROT_READ with MAP_SHARED with a following mprotect is not
 445          * allowed. Note that for r/w the kernel already prevents the mmap. */
 446         p = mmap(NULL,
 447                  mfd_def_size,
 448                  PROT_READ,
 449                  MAP_SHARED,
 450                  fd,
 451                  0);
 452         if (p != MAP_FAILED) {
 453                 r = mprotect(p, mfd_def_size, PROT_READ | PROT_WRITE);
 454                 if (r >= 0) {
 455                         printf("mmap()+mprotect() didn't fail as expected\n");
 456                         abort();
 457                 }
 458         }
 459
 460         /* verify PUNCH_HOLE fails */
 461         r = fallocate(fd,
 462                       FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
 463                       0,
 464                       mfd_def_size);
 465         if (r >= 0) {
 466                 printf("fallocate(PUNCH_HOLE) didn't fail as expected\n");
 467                 abort();
 468         }
 469 }
 470
 471 static void mfd_assert_shrink(int fd)
 472 {
 473         int r, fd2;
 474
 475         r = ftruncate(fd, mfd_def_size / 2);
 476         if (r < 0) {
 477                 printf("ftruncate(SHRINK) failed: %m\n");
 478                 abort();
 479         }
 480
 481         mfd_assert_size(fd, mfd_def_size / 2);
 482
 483         fd2 = mfd_assert_open(fd,
 484                               O_RDWR | O_CREAT | O_TRUNC,
 485                               S_IRUSR | S_IWUSR);
 486         close(fd2);
 487
 488         mfd_assert_size(fd, 0);
 489 }
 490
 491 static void mfd_fail_shrink(int fd)
 492 {
 493         int r;
 494
 495         r = ftruncate(fd, mfd_def_size / 2);
 496         if (r >= 0) {
 497                 printf("ftruncate(SHRINK) didn't fail as expected\n");
 498                 abort();
 499         }
 500
 501         mfd_fail_open(fd,
 502                       O_RDWR | O_CREAT | O_TRUNC,
 503                       S_IRUSR | S_IWUSR);
 504 }
 505
 506 static void mfd_assert_grow(int fd)
 507 {
 508         int r;
 509
 510         r = ftruncate(fd, mfd_def_size * 2);
 511         if (r < 0) {
 512                 printf("ftruncate(GROW) failed: %m\n");
 513                 abort();
 514         }
 515
 516         mfd_assert_size(fd, mfd_def_size * 2);
 517
 518         r = fallocate(fd,
 519                       0,
 520                       0,
 521                       mfd_def_size * 4);
 522         if (r < 0) {
 523                 printf("fallocate(ALLOC) failed: %m\n");
 524                 abort();
 525         }
 526
 527         mfd_assert_size(fd, mfd_def_size * 4);
 528 }
 529
 530 static void mfd_fail_grow(int fd)
 531 {
 532         int r;
 533
 534         r = ftruncate(fd, mfd_def_size * 2);
 535         if (r >= 0) {
 536                 printf("ftruncate(GROW) didn't fail as expected\n");
 537                 abort();
 538         }
 539
 540         r = fallocate(fd,
 541                       0,
 542                       0,
 543                       mfd_def_size * 4);
 544         if (r >= 0) {
 545                 printf("fallocate(ALLOC) didn't fail as expected\n");
 546                 abort();
 547         }
 548 }
 549
 550 static void mfd_assert_grow_write(int fd)
 551 {
 552         static char *buf;
 553         ssize_t l;
 554
 555         /* hugetlbfs does not support write */
 556         if (hugetlbfs_test)
 557                 return;
 558
 559         buf = malloc(mfd_def_size * 8);
 560         if (!buf) {
 561                 printf("malloc(%zu) failed: %m\n", mfd_def_size * 8);
 562                 abort();
 563         }
 564
 565         l = pwrite(fd, buf, mfd_def_size * 8, 0);
 566         if (l != (mfd_def_size * 8)) {
 567                 printf("pwrite() failed: %m\n");
 568                 abort();
 569         }
 570
 571         mfd_assert_size(fd, mfd_def_size * 8);
 572 }
 573
 574 static void mfd_fail_grow_write(int fd)
 575 {
 576         static char *buf;
 577         ssize_t l;
 578
 579         /* hugetlbfs does not support write */
 580         if (hugetlbfs_test)
 581                 return;
 582
 583         buf = malloc(mfd_def_size * 8);
 584         if (!buf) {
 585                 printf("malloc(%zu) failed: %m\n", mfd_def_size * 8);
 586                 abort();
 587         }
 588
 589         l = pwrite(fd, buf, mfd_def_size * 8, 0);
 590         if (l == (mfd_def_size * 8)) {
 591                 printf("pwrite() didn't fail as expected\n");
 592                 abort();
 593         }
 594 }
 595
 596 static int idle_thread_fn(void *arg)
 597 {
 598         sigset_t set;
 599         int sig;
 600
 601         /* dummy waiter; SIGTERM terminates us anyway */
 602         sigemptyset(&set);
 603         sigaddset(&set, SIGTERM);
 604         sigwait(&set, &sig);
 605
 606         return 0;
 607 }
 608
 609 static pid_t spawn_idle_thread(unsigned int flags)
 610 {
 611         uint8_t *stack;
 612         pid_t pid;
 613
 614         stack = malloc(STACK_SIZE);
 615         if (!stack) {
 616                 printf("malloc(STACK_SIZE) failed: %m\n");
 617                 abort();
 618         }
 619
 620         pid = clone(idle_thread_fn,
 621                     stack + STACK_SIZE,
 622                     SIGCHLD | flags,
 623                     NULL);
 624         if (pid < 0) {
 625                 printf("clone() failed: %m\n");
 626                 abort();
 627         }
 628
 629         return pid;
 630 }
 631
 632 static void join_idle_thread(pid_t pid)
 633 {
 634         kill(pid, SIGTERM);
 635         waitpid(pid, NULL, 0);
 636 }
 637
 638 /*
 639  * Test memfd_create() syscall
 640  * Verify syscall-argument validation, including name checks, flag validation
 641  * and more.
 642  */
 643 static void test_create(void)
 644 {
 645         char buf[2048];
 646         int fd;
 647
 648         printf("%s CREATE\n", memfd_str);
 649
 650         /* test NULL name */
 651         mfd_fail_new(NULL, 0);
 652
 653         /* test over-long name (not zero-terminated) */
 654         memset(buf, 0xff, sizeof(buf));
 655         mfd_fail_new(buf, 0);
 656
 657         /* test over-long zero-terminated name */
 658         memset(buf, 0xff, sizeof(buf));
 659         buf[sizeof(buf) - 1] = 0;
 660         mfd_fail_new(buf, 0);
 661
 662         /* verify "" is a valid name */
 663         fd = mfd_assert_new("", 0, 0);
 664         close(fd);
 665
 666         /* verify invalid O_* open flags */
 667         mfd_fail_new("", 0x0100);
 668         mfd_fail_new("", ~MFD_CLOEXEC);
 669         mfd_fail_new("", ~MFD_ALLOW_SEALING);
 670         mfd_fail_new("", ~0);
 671         mfd_fail_new("", 0x80000000U);
 672
 673         /* verify MFD_CLOEXEC is allowed */
 674         fd = mfd_assert_new("", 0, MFD_CLOEXEC);
 675         close(fd);
 676
 677         /* verify MFD_ALLOW_SEALING is allowed */
 678         fd = mfd_assert_new("", 0, MFD_ALLOW_SEALING);
 679         close(fd);
 680
 681         /* verify MFD_ALLOW_SEALING | MFD_CLOEXEC is allowed */
 682         fd = mfd_assert_new("", 0, MFD_ALLOW_SEALING | MFD_CLOEXEC);
 683         close(fd);
 684 }
 685
 686 /*
 687  * Test basic sealing
 688  * A very basic sealing test to see whether setting/retrieving seals works.
 689  */
 690 static void test_basic(void)
 691 {
 692         int fd;
 693
 694         printf("%s BASIC\n", memfd_str);
 695
 696         fd = mfd_assert_new("kern_memfd_basic",
 697                             mfd_def_size,
 698                             MFD_CLOEXEC | MFD_ALLOW_SEALING);
 699
 700         /* add basic seals */
 701         mfd_assert_has_seals(fd, 0);
 702         mfd_assert_add_seals(fd, F_SEAL_SHRINK |
 703                                  F_SEAL_WRITE);
 704         mfd_assert_has_seals(fd, F_SEAL_SHRINK |
 705                                  F_SEAL_WRITE);
 706
 707         /* add them again */
 708         mfd_assert_add_seals(fd, F_SEAL_SHRINK |
 709                                  F_SEAL_WRITE);
 710         mfd_assert_has_seals(fd, F_SEAL_SHRINK |
 711                                  F_SEAL_WRITE);
 712
 713         /* add more seals and seal against sealing */
 714         mfd_assert_add_seals(fd, F_SEAL_GROW | F_SEAL_SEAL);
 715         mfd_assert_has_seals(fd, F_SEAL_SHRINK |
 716                                  F_SEAL_GROW |
 717                                  F_SEAL_WRITE |
 718                                  F_SEAL_SEAL);
 719
 720         /* verify that sealing no longer works */
 721         mfd_fail_add_seals(fd, F_SEAL_GROW);
 722         mfd_fail_add_seals(fd, 0);
 723
 724         close(fd);
 725
 726         /* verify sealing does not work without MFD_ALLOW_SEALING */
 727         fd = mfd_assert_new("kern_memfd_basic",
 728                             mfd_def_size,
 729                             MFD_CLOEXEC);
 730         mfd_assert_has_seals(fd, F_SEAL_SEAL);
 731         mfd_fail_add_seals(fd, F_SEAL_SHRINK |
 732                                F_SEAL_GROW |
 733                                F_SEAL_WRITE);
 734         mfd_assert_has_seals(fd, F_SEAL_SEAL);
 735         close(fd);
 736 }
 737
 738 /*
 739  * Test SEAL_WRITE
 740  * Test whether SEAL_WRITE actually prevents modifications.
 741  */
 742 static void test_seal_write(void)
 743 {
 744         int fd;
 745
 746         printf("%s SEAL-WRITE\n", memfd_str);
 747
 748         fd = mfd_assert_new("kern_memfd_seal_write",
 749                             mfd_def_size,
 750                             MFD_CLOEXEC | MFD_ALLOW_SEALING);
 751         mfd_assert_has_seals(fd, 0);
 752         mfd_assert_add_seals(fd, F_SEAL_WRITE);
 753         mfd_assert_has_seals(fd, F_SEAL_WRITE);
 754
 755         mfd_assert_read(fd);
 756         mfd_fail_write(fd);
 757         mfd_assert_shrink(fd);
 758         mfd_assert_grow(fd);
 759         mfd_fail_grow_write(fd);
 760
 761         close(fd);
 762 }
 763
 764 /*
 765  * Test SEAL_FUTURE_WRITE
 766  * Test whether SEAL_FUTURE_WRITE actually prevents modifications.
 767  */
 768 static void test_seal_future_write(void)
 769 {
 770         int fd, fd2;
 771         void *p;
 772
 773         printf("%s SEAL-FUTURE-WRITE\n", memfd_str);
 774
 775         fd = mfd_assert_new("kern_memfd_seal_future_write",
 776                             mfd_def_size,
 777                             MFD_CLOEXEC | MFD_ALLOW_SEALING);
 778
 779         p = mfd_assert_mmap_shared(fd);
 780
 781         mfd_assert_has_seals(fd, 0);
 782
 783         mfd_assert_add_seals(fd, F_SEAL_FUTURE_WRITE);
 784         mfd_assert_has_seals(fd, F_SEAL_FUTURE_WRITE);
 785
 786         /* read should pass, writes should fail */
 787         mfd_assert_read(fd);
 788         mfd_assert_read_shared(fd);
 789         mfd_fail_write(fd);
 790
 791         fd2 = mfd_assert_reopen_fd(fd);
 792         /* read should pass, writes should still fail */
 793         mfd_assert_read(fd2);
 794         mfd_assert_read_shared(fd2);
 795         mfd_fail_write(fd2);
 796
 797         mfd_assert_fork_private_write(fd);
 798
 799         munmap(p, mfd_def_size);
 800         close(fd2);
 801         close(fd);
 802 }
 803
 804 /*
 805  * Test SEAL_SHRINK
 806  * Test whether SEAL_SHRINK actually prevents shrinking
 807  */
 808 static void test_seal_shrink(void)
 809 {
 810         int fd;
 811
 812         printf("%s SEAL-SHRINK\n", memfd_str);
 813
 814         fd = mfd_assert_new("kern_memfd_seal_shrink",
 815                             mfd_def_size,
 816                             MFD_CLOEXEC | MFD_ALLOW_SEALING);
 817         mfd_assert_has_seals(fd, 0);
 818         mfd_assert_add_seals(fd, F_SEAL_SHRINK);
 819         mfd_assert_has_seals(fd, F_SEAL_SHRINK);
 820
 821         mfd_assert_read(fd);
 822         mfd_assert_write(fd);
 823         mfd_fail_shrink(fd);
 824         mfd_assert_grow(fd);
 825         mfd_assert_grow_write(fd);
 826
 827         close(fd);
 828 }
 829
 830 /*
 831  * Test SEAL_GROW
 832  * Test whether SEAL_GROW actually prevents growing
 833  */
 834 static void test_seal_grow(void)
 835 {
 836         int fd;
 837
 838         printf("%s SEAL-GROW\n", memfd_str);
 839
 840         fd = mfd_assert_new("kern_memfd_seal_grow",
 841                             mfd_def_size,
 842                             MFD_CLOEXEC | MFD_ALLOW_SEALING);
 843         mfd_assert_has_seals(fd, 0);
 844         mfd_assert_add_seals(fd, F_SEAL_GROW);
 845         mfd_assert_has_seals(fd, F_SEAL_GROW);
 846
 847         mfd_assert_read(fd);
 848         mfd_assert_write(fd);
 849         mfd_assert_shrink(fd);
 850         mfd_fail_grow(fd);
 851         mfd_fail_grow_write(fd);
 852
 853         close(fd);
 854 }
 855
 856 /*
 857  * Test SEAL_SHRINK | SEAL_GROW
 858  * Test whether SEAL_SHRINK | SEAL_GROW actually prevents resizing
 859  */
 860 static void test_seal_resize(void)
 861 {
 862         int fd;
 863
 864         printf("%s SEAL-RESIZE\n", memfd_str);
 865
 866         fd = mfd_assert_new("kern_memfd_seal_resize",
 867                             mfd_def_size,
 868                             MFD_CLOEXEC | MFD_ALLOW_SEALING);
 869         mfd_assert_has_seals(fd, 0);
 870         mfd_assert_add_seals(fd, F_SEAL_SHRINK | F_SEAL_GROW);
 871         mfd_assert_has_seals(fd, F_SEAL_SHRINK | F_SEAL_GROW);
 872
 873         mfd_assert_read(fd);
 874         mfd_assert_write(fd);
 875         mfd_fail_shrink(fd);
 876         mfd_fail_grow(fd);
 877         mfd_fail_grow_write(fd);
 878
 879         close(fd);
 880 }
 881
 882 /*
 883  * Test sharing via dup()
 884  * Test that seals are shared between dupped FDs and they're all equal.
 885  */
 886 static void test_share_dup(char *banner, char *b_suffix)
 887 {
 888         int fd, fd2;
 889
 890         printf("%s %s %s\n", memfd_str, banner, b_suffix);
 891
 892         fd = mfd_assert_new("kern_memfd_share_dup",
 893                             mfd_def_size,
 894                             MFD_CLOEXEC | MFD_ALLOW_SEALING);
 895         mfd_assert_has_seals(fd, 0);
 896
 897         fd2 = mfd_assert_dup(fd);
 898         mfd_assert_has_seals(fd2, 0);
 899
 900         mfd_assert_add_seals(fd, F_SEAL_WRITE);
 901         mfd_assert_has_seals(fd, F_SEAL_WRITE);
 902         mfd_assert_has_seals(fd2, F_SEAL_WRITE);
 903
 904         mfd_assert_add_seals(fd2, F_SEAL_SHRINK);
 905         mfd_assert_has_seals(fd, F_SEAL_WRITE | F_SEAL_SHRINK);
 906         mfd_assert_has_seals(fd2, F_SEAL_WRITE | F_SEAL_SHRINK);
 907
 908         mfd_assert_add_seals(fd, F_SEAL_SEAL);
 909         mfd_assert_has_seals(fd, F_SEAL_WRITE | F_SEAL_SHRINK | F_SEAL_SEAL);
 910         mfd_assert_has_seals(fd2, F_SEAL_WRITE | F_SEAL_SHRINK | F_SEAL_SEAL);
 911
 912         mfd_fail_add_seals(fd, F_SEAL_GROW);
 913         mfd_fail_add_seals(fd2, F_SEAL_GROW);
 914         mfd_fail_add_seals(fd, F_SEAL_SEAL);
 915         mfd_fail_add_seals(fd2, F_SEAL_SEAL);
 916
 917         close(fd2);
 918
 919         mfd_fail_add_seals(fd, F_SEAL_GROW);
 920         close(fd);
 921 }
 922
 923 /*
 924  * Test sealing with active mmap()s
 925  * Modifying seals is only allowed if no other mmap() refs exist.
 926  */
 927 static void test_share_mmap(char *banner, char *b_suffix)
 928 {
 929         int fd;
 930         void *p;
 931
 932         printf("%s %s %s\n", memfd_str,  banner, b_suffix);
 933
 934         fd = mfd_assert_new("kern_memfd_share_mmap",
 935                             mfd_def_size,
 936                             MFD_CLOEXEC | MFD_ALLOW_SEALING);
 937         mfd_assert_has_seals(fd, 0);
 938
 939         /* shared/writable ref prevents sealing WRITE, but allows others */
 940         p = mfd_assert_mmap_shared(fd);
 941         mfd_fail_add_seals(fd, F_SEAL_WRITE);
 942         mfd_assert_has_seals(fd, 0);
 943         mfd_assert_add_seals(fd, F_SEAL_SHRINK);
 944         mfd_assert_has_seals(fd, F_SEAL_SHRINK);
 945         munmap(p, mfd_def_size);
 946
 947         /* readable ref allows sealing */
 948         p = mfd_assert_mmap_private(fd);
 949         mfd_assert_add_seals(fd, F_SEAL_WRITE);
 950         mfd_assert_has_seals(fd, F_SEAL_WRITE | F_SEAL_SHRINK);
 951         munmap(p, mfd_def_size);
 952
 953         close(fd);
 954 }
 955
 956 /*
 957  * Test sealing with open(/proc/self/fd/%d)
 958  * Via /proc we can get access to a separate file-context for the same memfd.
 959  * This is *not* like dup(), but like a real separate open(). Make sure the
 960  * semantics are as expected and we correctly check for RDONLY / WRONLY / RDWR.
 961  */
 962 static void test_share_open(char *banner, char *b_suffix)
 963 {
 964         int fd, fd2;
 965
 966         printf("%s %s %s\n", memfd_str, banner, b_suffix);
 967
 968         fd = mfd_assert_new("kern_memfd_share_open",
 969                             mfd_def_size,
 970                             MFD_CLOEXEC | MFD_ALLOW_SEALING);
 971         mfd_assert_has_seals(fd, 0);
 972
 973         fd2 = mfd_assert_open(fd, O_RDWR, 0);
 974         mfd_assert_add_seals(fd, F_SEAL_WRITE);
 975         mfd_assert_has_seals(fd, F_SEAL_WRITE);
 976         mfd_assert_has_seals(fd2, F_SEAL_WRITE);
 977
 978         mfd_assert_add_seals(fd2, F_SEAL_SHRINK);
 979         mfd_assert_has_seals(fd, F_SEAL_WRITE | F_SEAL_SHRINK);
 980         mfd_assert_has_seals(fd2, F_SEAL_WRITE | F_SEAL_SHRINK);
 981
 982         close(fd);
 983         fd = mfd_assert_open(fd2, O_RDONLY, 0);
 984
 985         mfd_fail_add_seals(fd, F_SEAL_SEAL);
 986         mfd_assert_has_seals(fd, F_SEAL_WRITE | F_SEAL_SHRINK);
 987         mfd_assert_has_seals(fd2, F_SEAL_WRITE | F_SEAL_SHRINK);
 988
 989         close(fd2);
 990         fd2 = mfd_assert_open(fd, O_RDWR, 0);
 991
 992         mfd_assert_add_seals(fd2, F_SEAL_SEAL);
 993         mfd_assert_has_seals(fd, F_SEAL_WRITE | F_SEAL_SHRINK | F_SEAL_SEAL);
 994         mfd_assert_has_seals(fd2, F_SEAL_WRITE | F_SEAL_SHRINK | F_SEAL_SEAL);
 995
 996         close(fd2);
 997         close(fd);
 998 }
 999
1000 /*
1001  * Test sharing via fork()
1002  * Test whether seal-modifications work as expected with forked childs.
1003  */
1004 static void test_share_fork(char *banner, char *b_suffix)
1005 {
1006         int fd;
1007         pid_t pid;
1008
1009         printf("%s %s %s\n", memfd_str, banner, b_suffix);
1010
1011         fd = mfd_assert_new("kern_memfd_share_fork",
1012                             mfd_def_size,
1013                             MFD_CLOEXEC | MFD_ALLOW_SEALING);
1014         mfd_assert_has_seals(fd, 0);
1015
1016         pid = spawn_idle_thread(0);
1017         mfd_assert_add_seals(fd, F_SEAL_SEAL);
1018         mfd_assert_has_seals(fd, F_SEAL_SEAL);
1019
1020         mfd_fail_add_seals(fd, F_SEAL_WRITE);
1021         mfd_assert_has_seals(fd, F_SEAL_SEAL);
1022
1023         join_idle_thread(pid);
1024
1025         mfd_fail_add_seals(fd, F_SEAL_WRITE);
1026         mfd_assert_has_seals(fd, F_SEAL_SEAL);
1027
1028         close(fd);
1029 }
1030
1031 int main(int argc, char **argv)
1032 {
1033         pid_t pid;
1034
1035         if (argc == 2) {
1036                 if (!strcmp(argv[1], "hugetlbfs")) {
1037                         unsigned long hpage_size = default_huge_page_size();
1038
1039                         if (!hpage_size) {
1040                                 printf("Unable to determine huge page size\n");
1041                                 abort();
1042                         }
1043
1044                         hugetlbfs_test = 1;
1045                         memfd_str = MEMFD_HUGE_STR;
1046                         mfd_def_size = hpage_size * 2;
1047                 } else {
1048                         printf("Unknown option: %s\n", argv[1]);
1049                         abort();
1050                 }
1051         }
1052
1053         test_create();
1054         test_basic();
1055
1056         test_seal_write();
1057         test_seal_future_write();
1058         test_seal_shrink();
1059         test_seal_grow();
1060         test_seal_resize();
1061
1062         test_share_dup("SHARE-DUP", "");
1063         test_share_mmap("SHARE-MMAP", "");
1064         test_share_open("SHARE-OPEN", "");
1065         test_share_fork("SHARE-FORK", "");
1066
1067         /* Run test-suite in a multi-threaded environment with a shared
1068          * file-table. */
1069         pid = spawn_idle_thread(CLONE_FILES | CLONE_FS | CLONE_VM);
1070         test_share_dup("SHARE-DUP", SHARED_FT_STR);
1071         test_share_mmap("SHARE-MMAP", SHARED_FT_STR);
1072         test_share_open("SHARE-OPEN", SHARED_FT_STR);
1073         test_share_fork("SHARE-FORK", SHARED_FT_STR);
1074         join_idle_thread(pid);
1075
1076         printf("memfd: DONE\n");
1077
1078         return 0;
1079 }