| 1 | /* |
| 2 | * Copyright (c) 2018 Virtuozzo International GmbH |
| 3 | * |
| 4 | * This work is licensed under the terms of the GNU GPL, version 2 or later. |
| 5 | * |
| 6 | */ |
| 7 | |
| 8 | #include "qemu/osdep.h" |
| 9 | #include "qemu/host-utils.h" |
| 10 | #include "err.h" |
| 11 | #include "qemu_elf.h" |
| 12 | |
| 13 | #define QEMU_NOTE_NAME "QEMU" |
| 14 | |
| 15 | #ifndef ROUND_UP |
| 16 | #define ROUND_UP(n, d) (((n) + (d) - 1) & -(0 ? (n) : (d))) |
| 17 | #endif |
| 18 | |
| 19 | int is_system(QEMUCPUState *s) |
| 20 | { |
| 21 | return s->gs.base >> 63; |
| 22 | } |
| 23 | |
| 24 | Elf64_Phdr *elf64_getphdr(void *map) |
| 25 | { |
| 26 | Elf64_Ehdr *ehdr = map; |
| 27 | Elf64_Phdr *phdr = (void *)((uint8_t *)map + ehdr->e_phoff); |
| 28 | |
| 29 | return phdr; |
| 30 | } |
| 31 | |
| 32 | Elf64_Half elf_getphdrnum(void *map) |
| 33 | { |
| 34 | Elf64_Ehdr *ehdr = map; |
| 35 | |
| 36 | return ehdr->e_phnum; |
| 37 | } |
| 38 | |
| 39 | static bool advance_note_offset(uint64_t *offsetp, uint64_t size, uint64_t end) |
| 40 | { |
| 41 | uint64_t offset = *offsetp; |
| 42 | |
| 43 | if (uadd64_overflow(offset, size, &offset) || offset > UINT64_MAX - 3) { |
| 44 | return false; |
| 45 | } |
| 46 | |
| 47 | offset = ROUND_UP(offset, 4); |
| 48 | |
| 49 | if (offset > end) { |
| 50 | return false; |
| 51 | } |
| 52 | |
| 53 | *offsetp = offset; |
| 54 | |
| 55 | return true; |
| 56 | } |
| 57 | |
| 58 | static bool init_states(QEMU_Elf *qe) |
| 59 | { |
| 60 | Elf64_Phdr *phdr = elf64_getphdr(qe->map); |
| 61 | Elf64_Nhdr *nhdr; |
| 62 | GPtrArray *states; |
| 63 | QEMUCPUState *state; |
| 64 | uint32_t state_size; |
| 65 | uint64_t offset; |
| 66 | uint64_t end_offset; |
| 67 | char *name; |
| 68 | |
| 69 | if (phdr[0].p_type != PT_NOTE) { |
| 70 | eprintf("Failed to find PT_NOTE\n"); |
| 71 | return false; |
| 72 | } |
| 73 | |
| 74 | qe->has_kernel_gs_base = 1; |
| 75 | offset = phdr[0].p_offset; |
| 76 | states = g_ptr_array_new(); |
| 77 | |
| 78 | if (uadd64_overflow(offset, phdr[0].p_memsz, &end_offset) || |
| 79 | end_offset > qe->size) { |
| 80 | end_offset = qe->size; |
| 81 | } |
| 82 | |
| 83 | while (offset < end_offset) { |
| 84 | nhdr = (void *)((uint8_t *)qe->map + offset); |
| 85 | |
| 86 | if (!advance_note_offset(&offset, sizeof(*nhdr), end_offset)) { |
| 87 | break; |
| 88 | } |
| 89 | |
| 90 | name = (char *)qe->map + offset; |
| 91 | |
| 92 | if (!advance_note_offset(&offset, nhdr->n_namesz, end_offset)) { |
| 93 | break; |
| 94 | } |
| 95 | |
| 96 | state = (void *)((uint8_t *)qe->map + offset); |
| 97 | |
| 98 | if (!advance_note_offset(&offset, nhdr->n_descsz, end_offset)) { |
| 99 | break; |
| 100 | } |
| 101 | |
| 102 | if (!strcmp(name, QEMU_NOTE_NAME) && |
| 103 | nhdr->n_descsz >= offsetof(QEMUCPUState, kernel_gs_base)) { |
| 104 | state_size = MIN(state->size, nhdr->n_descsz); |
| 105 | |
| 106 | if (state_size < sizeof(*state)) { |
| 107 | eprintf("CPU #%u: QEMU CPU state size %u doesn't match\n", |
| 108 | states->len, state_size); |
| 109 | /* |
| 110 | * We assume either every QEMU CPU state has KERNEL_GS_BASE or |
| 111 | * no one has. |
| 112 | */ |
| 113 | qe->has_kernel_gs_base = 0; |
| 114 | } |
| 115 | g_ptr_array_add(states, state); |
| 116 | } |
| 117 | } |
| 118 | |
| 119 | printf("%u CPU states has been found\n", states->len); |
| 120 | |
| 121 | qe->state_nr = states->len; |
| 122 | qe->state = (void *)g_ptr_array_free(states, FALSE); |
| 123 | |
| 124 | return true; |
| 125 | } |
| 126 | |
| 127 | static void exit_states(QEMU_Elf *qe) |
| 128 | { |
| 129 | g_free(qe->state); |
| 130 | } |
| 131 | |
| 132 | static bool check_ehdr(QEMU_Elf *qe) |
| 133 | { |
| 134 | Elf64_Ehdr *ehdr = qe->map; |
| 135 | uint64_t phendoff; |
| 136 | |
| 137 | if (sizeof(Elf64_Ehdr) > qe->size) { |
| 138 | eprintf("Invalid input dump file size\n"); |
| 139 | return false; |
| 140 | } |
| 141 | |
| 142 | if (memcmp(ehdr->e_ident, ELFMAG, SELFMAG)) { |
| 143 | eprintf("Invalid ELF signature, input file is not ELF\n"); |
| 144 | return false; |
| 145 | } |
| 146 | |
| 147 | if (ehdr->e_ident[EI_CLASS] != ELFCLASS64 || |
| 148 | ehdr->e_ident[EI_DATA] != ELFDATA2LSB) { |
| 149 | eprintf("Invalid ELF class or byte order, must be 64-bit LE\n"); |
| 150 | return false; |
| 151 | } |
| 152 | |
| 153 | if (ehdr->e_ident[EI_VERSION] != EV_CURRENT) { |
| 154 | eprintf("Invalid ELF version\n"); |
| 155 | return false; |
| 156 | } |
| 157 | |
| 158 | if (ehdr->e_machine != EM_X86_64) { |
| 159 | eprintf("Invalid input dump architecture, only x86_64 is supported\n"); |
| 160 | return false; |
| 161 | } |
| 162 | |
| 163 | if (ehdr->e_type != ET_CORE) { |
| 164 | eprintf("Invalid ELF type, must be core file\n"); |
| 165 | return false; |
| 166 | } |
| 167 | |
| 168 | /* |
| 169 | * ELF dump file must contain one PT_NOTE and at least one PT_LOAD to |
| 170 | * restore physical address space. |
| 171 | */ |
| 172 | if (ehdr->e_phnum < 2) { |
| 173 | eprintf("Invalid number of ELF program headers\n"); |
| 174 | return false; |
| 175 | } |
| 176 | |
| 177 | if (umul64_overflow(ehdr->e_phnum, sizeof(Elf64_Phdr), &phendoff) || |
| 178 | uadd64_overflow(phendoff, ehdr->e_phoff, &phendoff) || |
| 179 | phendoff > qe->size) { |
| 180 | eprintf("phdrs do not fit in file\n"); |
| 181 | return false; |
| 182 | } |
| 183 | |
| 184 | return true; |
| 185 | } |
| 186 | |
| 187 | static bool QEMU_Elf_map(QEMU_Elf *qe, const char *filename) |
| 188 | { |
| 189 | #ifdef CONFIG_LINUX |
| 190 | struct stat st; |
| 191 | int fd; |
| 192 | |
| 193 | printf("Using Linux mmap\n"); |
| 194 | |
| 195 | fd = open(filename, O_RDONLY, 0); |
| 196 | if (fd == -1) { |
| 197 | eprintf("Failed to open ELF dump file \'%s\'\n", filename); |
| 198 | return false; |
| 199 | } |
| 200 | |
| 201 | if (fstat(fd, &st)) { |
| 202 | eprintf("Failed to get size of ELF dump file\n"); |
| 203 | close(fd); |
| 204 | return false; |
| 205 | } |
| 206 | qe->size = st.st_size; |
| 207 | |
| 208 | qe->map = mmap(NULL, qe->size, PROT_READ | PROT_WRITE, |
| 209 | MAP_PRIVATE | MAP_NORESERVE, fd, 0); |
| 210 | if (qe->map == MAP_FAILED) { |
| 211 | eprintf("Failed to map ELF file\n"); |
| 212 | close(fd); |
| 213 | return false; |
| 214 | } |
| 215 | |
| 216 | close(fd); |
| 217 | #else |
| 218 | GError *gerr = NULL; |
| 219 | |
| 220 | printf("Using GLib mmap\n"); |
| 221 | |
| 222 | qe->gmf = g_mapped_file_new(filename, TRUE, &gerr); |
| 223 | if (gerr) { |
| 224 | eprintf("Failed to map ELF dump file \'%s\'\n", filename); |
| 225 | g_error_free(gerr); |
| 226 | return false; |
| 227 | } |
| 228 | |
| 229 | qe->map = g_mapped_file_get_contents(qe->gmf); |
| 230 | qe->size = g_mapped_file_get_length(qe->gmf); |
| 231 | #endif |
| 232 | |
| 233 | return true; |
| 234 | } |
| 235 | |
| 236 | static void QEMU_Elf_unmap(QEMU_Elf *qe) |
| 237 | { |
| 238 | #ifdef CONFIG_LINUX |
| 239 | munmap(qe->map, qe->size); |
| 240 | #else |
| 241 | g_mapped_file_unref(qe->gmf); |
| 242 | #endif |
| 243 | } |
| 244 | |
| 245 | bool QEMU_Elf_init(QEMU_Elf *qe, const char *filename) |
| 246 | { |
| 247 | if (!QEMU_Elf_map(qe, filename)) { |
| 248 | return false; |
| 249 | } |
| 250 | |
| 251 | if (!check_ehdr(qe)) { |
| 252 | eprintf("Input file has the wrong format\n"); |
| 253 | QEMU_Elf_unmap(qe); |
| 254 | return false; |
| 255 | } |
| 256 | |
| 257 | if (!init_states(qe)) { |
| 258 | eprintf("Failed to extract QEMU CPU states\n"); |
| 259 | QEMU_Elf_unmap(qe); |
| 260 | return false; |
| 261 | } |
| 262 | |
| 263 | return true; |
| 264 | } |
| 265 | |
| 266 | void QEMU_Elf_exit(QEMU_Elf *qe) |
| 267 | { |
| 268 | exit_states(qe); |
| 269 | QEMU_Elf_unmap(qe); |
| 270 | } |