1 /* 2 * misc.c 3 * 4 * This is a collection of several routines used to extract the kernel 5 * which includes KASLR relocation, decompression, ELF parsing, and 6 * relocation processing. Additionally included are the screen and serial 7 * output functions and related debugging support functions. 8 * 9 * malloc by Hannu Savolainen 1993 and Matthias Urlichs 1994 10 * puts by Nick Holloway 1993, better puts by Martin Mares 1995 11 * High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996 12 */ 13 14 #include "misc.h" 15 #include "error.h" 16 #include "../string.h" 17 #include "../voffset.h" 18 19 /* 20 * WARNING!! 21 * This code is compiled with -fPIC and it is relocated dynamically at 22 * run time, but no relocation processing is performed. This means that 23 * it is not safe to place pointers in static structures. 24 */ 25 26 /* Macros used by the included decompressor code below. */ 27 #define STATIC static 28 29 /* 30 * Use normal definitions of mem*() from string.c. There are already 31 * included header files which expect a definition of memset() and by 32 * the time we define memset macro, it is too late. 33 */ 34 #undef memcpy 35 #undef memset 36 #define memzero(s, n) memset((s), 0, (n)) 37 #define memmove memmove 38 39 /* Functions used by the included decompressor code below. */ 40 void *memmove(void *dest, const void *src, size_t n); 41 42 /* 43 * This is set up by the setup-routine at boot-time 44 */ 45 struct boot_params *boot_params; 46 47 memptr free_mem_ptr; 48 memptr free_mem_end_ptr; 49 50 static char *vidmem; 51 static int vidport; 52 static int lines, cols; 53 54 #ifdef CONFIG_KERNEL_GZIP 55 #include "../../../../lib/decompress_inflate.c" 56 #endif 57 58 #ifdef CONFIG_KERNEL_BZIP2 59 #include "../../../../lib/decompress_bunzip2.c" 60 #endif 61 62 #ifdef CONFIG_KERNEL_LZMA 63 #include "../../../../lib/decompress_unlzma.c" 64 #endif 65 66 #ifdef CONFIG_KERNEL_XZ 67 #include "../../../../lib/decompress_unxz.c" 68 #endif 69 70 #ifdef CONFIG_KERNEL_LZO 71 #include "../../../../lib/decompress_unlzo.c" 72 #endif 73 74 #ifdef CONFIG_KERNEL_LZ4 75 #include "../../../../lib/decompress_unlz4.c" 76 #endif 77 /* 78 * NOTE: When adding a new decompressor, please update the analysis in 79 * ../header.S. 80 */ 81 82 static void scroll(void) 83 { 84 int i; 85 86 memmove(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2); 87 for (i = (lines - 1) * cols * 2; i < lines * cols * 2; i += 2) 88 vidmem[i] = ' '; 89 } 90 91 #define XMTRDY 0x20 92 93 #define TXR 0 /* Transmit register (WRITE) */ 94 #define LSR 5 /* Line Status */ 95 static void serial_putchar(int ch) 96 { 97 unsigned timeout = 0xffff; 98 99 while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout) 100 cpu_relax(); 101 102 outb(ch, early_serial_base + TXR); 103 } 104 105 void __putstr(const char *s) 106 { 107 int x, y, pos; 108 char c; 109 110 if (early_serial_base) { 111 const char *str = s; 112 while (*str) { 113 if (*str == '\n') 114 serial_putchar('\r'); 115 serial_putchar(*str++); 116 } 117 } 118 119 if (lines == 0 || cols == 0) 120 return; 121 122 x = boot_params->screen_info.orig_x; 123 y = boot_params->screen_info.orig_y; 124 125 while ((c = *s++) != '\0') { 126 if (c == '\n') { 127 x = 0; 128 if (++y >= lines) { 129 scroll(); 130 y--; 131 } 132 } else { 133 vidmem[(x + cols * y) * 2] = c; 134 if (++x >= cols) { 135 x = 0; 136 if (++y >= lines) { 137 scroll(); 138 y--; 139 } 140 } 141 } 142 } 143 144 boot_params->screen_info.orig_x = x; 145 boot_params->screen_info.orig_y = y; 146 147 pos = (x + cols * y) * 2; /* Update cursor position */ 148 outb(14, vidport); 149 outb(0xff & (pos >> 9), vidport+1); 150 outb(15, vidport); 151 outb(0xff & (pos >> 1), vidport+1); 152 } 153 154 void __puthex(unsigned long value) 155 { 156 char alpha[2] = "0"; 157 int bits; 158 159 for (bits = sizeof(value) * 8 - 4; bits >= 0; bits -= 4) { 160 unsigned long digit = (value >> bits) & 0xf; 161 162 if (digit < 0xA) 163 alpha[0] = '0' + digit; 164 else 165 alpha[0] = 'a' + (digit - 0xA); 166 167 __putstr(alpha); 168 } 169 } 170 171 #if CONFIG_X86_NEED_RELOCS 172 static void handle_relocations(void *output, unsigned long output_len, 173 unsigned long virt_addr) 174 { 175 int *reloc; 176 unsigned long delta, map, ptr; 177 unsigned long min_addr = (unsigned long)output; 178 unsigned long max_addr = min_addr + (VO___bss_start - VO__text); 179 180 /* 181 * Calculate the delta between where vmlinux was linked to load 182 * and where it was actually loaded. 183 */ 184 delta = min_addr - LOAD_PHYSICAL_ADDR; 185 186 /* 187 * The kernel contains a table of relocation addresses. Those 188 * addresses have the final load address of the kernel in virtual 189 * memory. We are currently working in the self map. So we need to 190 * create an adjustment for kernel memory addresses to the self map. 191 * This will involve subtracting out the base address of the kernel. 192 */ 193 map = delta - __START_KERNEL_map; 194 195 /* 196 * 32-bit always performs relocations. 64-bit relocations are only 197 * needed if KASLR has chosen a different starting address offset 198 * from __START_KERNEL_map. 199 */ 200 if (IS_ENABLED(CONFIG_X86_64)) 201 delta = virt_addr - LOAD_PHYSICAL_ADDR; 202 203 if (!delta) { 204 debug_putstr("No relocation needed... "); 205 return; 206 } 207 debug_putstr("Performing relocations... "); 208 209 /* 210 * Process relocations: 32 bit relocations first then 64 bit after. 211 * Three sets of binary relocations are added to the end of the kernel 212 * before compression. Each relocation table entry is the kernel 213 * address of the location which needs to be updated stored as a 214 * 32-bit value which is sign extended to 64 bits. 215 * 216 * Format is: 217 * 218 * kernel bits... 219 * 0 - zero terminator for 64 bit relocations 220 * 64 bit relocation repeated 221 * 0 - zero terminator for inverse 32 bit relocations 222 * 32 bit inverse relocation repeated 223 * 0 - zero terminator for 32 bit relocations 224 * 32 bit relocation repeated 225 * 226 * So we work backwards from the end of the decompressed image. 227 */ 228 for (reloc = output + output_len - sizeof(*reloc); *reloc; reloc--) { 229 long extended = *reloc; 230 extended += map; 231 232 ptr = (unsigned long)extended; 233 if (ptr < min_addr || ptr > max_addr) 234 error("32-bit relocation outside of kernel!\n"); 235 236 *(uint32_t *)ptr += delta; 237 } 238 #ifdef CONFIG_X86_64 239 while (*--reloc) { 240 long extended = *reloc; 241 extended += map; 242 243 ptr = (unsigned long)extended; 244 if (ptr < min_addr || ptr > max_addr) 245 error("inverse 32-bit relocation outside of kernel!\n"); 246 247 *(int32_t *)ptr -= delta; 248 } 249 for (reloc--; *reloc; reloc--) { 250 long extended = *reloc; 251 extended += map; 252 253 ptr = (unsigned long)extended; 254 if (ptr < min_addr || ptr > max_addr) 255 error("64-bit relocation outside of kernel!\n"); 256 257 *(uint64_t *)ptr += delta; 258 } 259 #endif 260 } 261 #else 262 static inline void handle_relocations(void *output, unsigned long output_len, 263 unsigned long virt_addr) 264 { } 265 #endif 266 267 static void parse_elf(void *output) 268 { 269 #ifdef CONFIG_X86_64 270 Elf64_Ehdr ehdr; 271 Elf64_Phdr *phdrs, *phdr; 272 #else 273 Elf32_Ehdr ehdr; 274 Elf32_Phdr *phdrs, *phdr; 275 #endif 276 void *dest; 277 int i; 278 279 memcpy(&ehdr, output, sizeof(ehdr)); 280 if (ehdr.e_ident[EI_MAG0] != ELFMAG0 || 281 ehdr.e_ident[EI_MAG1] != ELFMAG1 || 282 ehdr.e_ident[EI_MAG2] != ELFMAG2 || 283 ehdr.e_ident[EI_MAG3] != ELFMAG3) { 284 error("Kernel is not a valid ELF file"); 285 return; 286 } 287 288 debug_putstr("Parsing ELF... "); 289 290 phdrs = malloc(sizeof(*phdrs) * ehdr.e_phnum); 291 if (!phdrs) 292 error("Failed to allocate space for phdrs"); 293 294 memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum); 295 296 for (i = 0; i < ehdr.e_phnum; i++) { 297 phdr = &phdrs[i]; 298 299 switch (phdr->p_type) { 300 case PT_LOAD: 301 #ifdef CONFIG_RELOCATABLE 302 dest = output; 303 dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR); 304 #else 305 dest = (void *)(phdr->p_paddr); 306 #endif 307 memmove(dest, output + phdr->p_offset, phdr->p_filesz); 308 break; 309 default: /* Ignore other PT_* */ break; 310 } 311 } 312 313 free(phdrs); 314 } 315 316 /* 317 * The compressed kernel image (ZO), has been moved so that its position 318 * is against the end of the buffer used to hold the uncompressed kernel 319 * image (VO) and the execution environment (.bss, .brk), which makes sure 320 * there is room to do the in-place decompression. (See header.S for the 321 * calculations.) 322 * 323 * |-----compressed kernel image------| 324 * V V 325 * 0 extract_offset +INIT_SIZE 326 * |-----------|---------------|-------------------------|--------| 327 * | | | | 328 * VO__text startup_32 of ZO VO__end ZO__end 329 * ^ ^ 330 * |-------uncompressed kernel image---------| 331 * 332 */ 333 asmlinkage __visible void *extract_kernel(void *rmode, memptr heap, 334 unsigned char *input_data, 335 unsigned long input_len, 336 unsigned char *output, 337 unsigned long output_len) 338 { 339 const unsigned long kernel_total_size = VO__end - VO__text; 340 unsigned long virt_addr = LOAD_PHYSICAL_ADDR; 341 342 /* Retain x86 boot parameters pointer passed from startup_32/64. */ 343 boot_params = rmode; 344 345 /* Clear flags intended for solely in-kernel use. */ 346 boot_params->hdr.loadflags &= ~KASLR_FLAG; 347 348 sanitize_boot_params(boot_params); 349 350 if (boot_params->screen_info.orig_video_mode == 7) { 351 vidmem = (char *) 0xb0000; 352 vidport = 0x3b4; 353 } else { 354 vidmem = (char *) 0xb8000; 355 vidport = 0x3d4; 356 } 357 358 lines = boot_params->screen_info.orig_video_lines; 359 cols = boot_params->screen_info.orig_video_cols; 360 361 console_init(); 362 debug_putstr("early console in extract_kernel\n"); 363 364 free_mem_ptr = heap; /* Heap */ 365 free_mem_end_ptr = heap + BOOT_HEAP_SIZE; 366 367 /* Report initial kernel position details. */ 368 debug_putaddr(input_data); 369 debug_putaddr(input_len); 370 debug_putaddr(output); 371 debug_putaddr(output_len); 372 debug_putaddr(kernel_total_size); 373 374 /* 375 * The memory hole needed for the kernel is the larger of either 376 * the entire decompressed kernel plus relocation table, or the 377 * entire decompressed kernel plus .bss and .brk sections. 378 */ 379 choose_random_location((unsigned long)input_data, input_len, 380 (unsigned long *)&output, 381 max(output_len, kernel_total_size), 382 &virt_addr); 383 384 /* Validate memory location choices. */ 385 if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1)) 386 error("Destination physical address inappropriately aligned"); 387 if (virt_addr & (MIN_KERNEL_ALIGN - 1)) 388 error("Destination virtual address inappropriately aligned"); 389 #ifdef CONFIG_X86_64 390 if (heap > 0x3fffffffffffUL) 391 error("Destination address too large"); 392 if (virt_addr + max(output_len, kernel_total_size) > KERNEL_IMAGE_SIZE) 393 error("Destination virtual address is beyond the kernel mapping area"); 394 #else 395 if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff)) 396 error("Destination address too large"); 397 #endif 398 #ifndef CONFIG_RELOCATABLE 399 if ((unsigned long)output != LOAD_PHYSICAL_ADDR) 400 error("Destination address does not match LOAD_PHYSICAL_ADDR"); 401 if (virt_addr != LOAD_PHYSICAL_ADDR) 402 error("Destination virtual address changed when not relocatable"); 403 #endif 404 405 debug_putstr("\nDecompressing Linux... "); 406 __decompress(input_data, input_len, NULL, NULL, output, output_len, 407 NULL, error); 408 parse_elf(output); 409 handle_relocations(output, output_len, virt_addr); 410 debug_putstr("done.\nBooting the kernel.\n"); 411 return output; 412 } 413 414 void fortify_panic(const char *name) 415 { 416 error("detected buffer overflow"); 417 } 418