1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * misc.c 4 * 5 * This is a collection of several routines used to extract the kernel 6 * which includes KASLR relocation, decompression, ELF parsing, and 7 * relocation processing. Additionally included are the screen and serial 8 * output functions and related debugging support functions. 9 * 10 * malloc by Hannu Savolainen 1993 and Matthias Urlichs 1994 11 * puts by Nick Holloway 1993, better puts by Martin Mares 1995 12 * High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996 13 */ 14 15 #include "misc.h" 16 #include "error.h" 17 #include "pgtable.h" 18 #include "../string.h" 19 #include "../voffset.h" 20 #include <asm/bootparam_utils.h> 21 22 /* 23 * WARNING!! 24 * This code is compiled with -fPIC and it is relocated dynamically at 25 * run time, but no relocation processing is performed. This means that 26 * it is not safe to place pointers in static structures. 27 */ 28 29 /* Macros used by the included decompressor code below. */ 30 #define STATIC static 31 32 /* 33 * Provide definitions of memzero and memmove as some of the decompressors will 34 * try to define their own functions if these are not defined as macros. 35 */ 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 #ifdef CONFIG_KERNEL_ZSTD 79 #include "../../../../lib/decompress_unzstd.c" 80 #endif 81 /* 82 * NOTE: When adding a new decompressor, please update the analysis in 83 * ../header.S. 84 */ 85 86 static void scroll(void) 87 { 88 int i; 89 90 memmove(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2); 91 for (i = (lines - 1) * cols * 2; i < lines * cols * 2; i += 2) 92 vidmem[i] = ' '; 93 } 94 95 #define XMTRDY 0x20 96 97 #define TXR 0 /* Transmit register (WRITE) */ 98 #define LSR 5 /* Line Status */ 99 static void serial_putchar(int ch) 100 { 101 unsigned timeout = 0xffff; 102 103 while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout) 104 cpu_relax(); 105 106 outb(ch, early_serial_base + TXR); 107 } 108 109 void __putstr(const char *s) 110 { 111 int x, y, pos; 112 char c; 113 114 if (early_serial_base) { 115 const char *str = s; 116 while (*str) { 117 if (*str == '\n') 118 serial_putchar('\r'); 119 serial_putchar(*str++); 120 } 121 } 122 123 if (lines == 0 || cols == 0) 124 return; 125 126 x = boot_params->screen_info.orig_x; 127 y = boot_params->screen_info.orig_y; 128 129 while ((c = *s++) != '\0') { 130 if (c == '\n') { 131 x = 0; 132 if (++y >= lines) { 133 scroll(); 134 y--; 135 } 136 } else { 137 vidmem[(x + cols * y) * 2] = c; 138 if (++x >= cols) { 139 x = 0; 140 if (++y >= lines) { 141 scroll(); 142 y--; 143 } 144 } 145 } 146 } 147 148 boot_params->screen_info.orig_x = x; 149 boot_params->screen_info.orig_y = y; 150 151 pos = (x + cols * y) * 2; /* Update cursor position */ 152 outb(14, vidport); 153 outb(0xff & (pos >> 9), vidport+1); 154 outb(15, vidport); 155 outb(0xff & (pos >> 1), vidport+1); 156 } 157 158 void __puthex(unsigned long value) 159 { 160 char alpha[2] = "0"; 161 int bits; 162 163 for (bits = sizeof(value) * 8 - 4; bits >= 0; bits -= 4) { 164 unsigned long digit = (value >> bits) & 0xf; 165 166 if (digit < 0xA) 167 alpha[0] = '0' + digit; 168 else 169 alpha[0] = 'a' + (digit - 0xA); 170 171 __putstr(alpha); 172 } 173 } 174 175 #ifdef CONFIG_X86_NEED_RELOCS 176 static void handle_relocations(void *output, unsigned long output_len, 177 unsigned long virt_addr) 178 { 179 int *reloc; 180 unsigned long delta, map, ptr; 181 unsigned long min_addr = (unsigned long)output; 182 unsigned long max_addr = min_addr + (VO___bss_start - VO__text); 183 184 /* 185 * Calculate the delta between where vmlinux was linked to load 186 * and where it was actually loaded. 187 */ 188 delta = min_addr - LOAD_PHYSICAL_ADDR; 189 190 /* 191 * The kernel contains a table of relocation addresses. Those 192 * addresses have the final load address of the kernel in virtual 193 * memory. We are currently working in the self map. So we need to 194 * create an adjustment for kernel memory addresses to the self map. 195 * This will involve subtracting out the base address of the kernel. 196 */ 197 map = delta - __START_KERNEL_map; 198 199 /* 200 * 32-bit always performs relocations. 64-bit relocations are only 201 * needed if KASLR has chosen a different starting address offset 202 * from __START_KERNEL_map. 203 */ 204 if (IS_ENABLED(CONFIG_X86_64)) 205 delta = virt_addr - LOAD_PHYSICAL_ADDR; 206 207 if (!delta) { 208 debug_putstr("No relocation needed... "); 209 return; 210 } 211 debug_putstr("Performing relocations... "); 212 213 /* 214 * Process relocations: 32 bit relocations first then 64 bit after. 215 * Three sets of binary relocations are added to the end of the kernel 216 * before compression. Each relocation table entry is the kernel 217 * address of the location which needs to be updated stored as a 218 * 32-bit value which is sign extended to 64 bits. 219 * 220 * Format is: 221 * 222 * kernel bits... 223 * 0 - zero terminator for 64 bit relocations 224 * 64 bit relocation repeated 225 * 0 - zero terminator for inverse 32 bit relocations 226 * 32 bit inverse relocation repeated 227 * 0 - zero terminator for 32 bit relocations 228 * 32 bit relocation repeated 229 * 230 * So we work backwards from the end of the decompressed image. 231 */ 232 for (reloc = output + output_len - sizeof(*reloc); *reloc; reloc--) { 233 long extended = *reloc; 234 extended += map; 235 236 ptr = (unsigned long)extended; 237 if (ptr < min_addr || ptr > max_addr) 238 error("32-bit relocation outside of kernel!\n"); 239 240 *(uint32_t *)ptr += delta; 241 } 242 #ifdef CONFIG_X86_64 243 while (*--reloc) { 244 long extended = *reloc; 245 extended += map; 246 247 ptr = (unsigned long)extended; 248 if (ptr < min_addr || ptr > max_addr) 249 error("inverse 32-bit relocation outside of kernel!\n"); 250 251 *(int32_t *)ptr -= delta; 252 } 253 for (reloc--; *reloc; reloc--) { 254 long extended = *reloc; 255 extended += map; 256 257 ptr = (unsigned long)extended; 258 if (ptr < min_addr || ptr > max_addr) 259 error("64-bit relocation outside of kernel!\n"); 260 261 *(uint64_t *)ptr += delta; 262 } 263 #endif 264 } 265 #else 266 static inline void handle_relocations(void *output, unsigned long output_len, 267 unsigned long virt_addr) 268 { } 269 #endif 270 271 static void parse_elf(void *output) 272 { 273 #ifdef CONFIG_X86_64 274 Elf64_Ehdr ehdr; 275 Elf64_Phdr *phdrs, *phdr; 276 #else 277 Elf32_Ehdr ehdr; 278 Elf32_Phdr *phdrs, *phdr; 279 #endif 280 void *dest; 281 int i; 282 283 memcpy(&ehdr, output, sizeof(ehdr)); 284 if (ehdr.e_ident[EI_MAG0] != ELFMAG0 || 285 ehdr.e_ident[EI_MAG1] != ELFMAG1 || 286 ehdr.e_ident[EI_MAG2] != ELFMAG2 || 287 ehdr.e_ident[EI_MAG3] != ELFMAG3) { 288 error("Kernel is not a valid ELF file"); 289 return; 290 } 291 292 debug_putstr("Parsing ELF... "); 293 294 phdrs = malloc(sizeof(*phdrs) * ehdr.e_phnum); 295 if (!phdrs) 296 error("Failed to allocate space for phdrs"); 297 298 memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum); 299 300 for (i = 0; i < ehdr.e_phnum; i++) { 301 phdr = &phdrs[i]; 302 303 switch (phdr->p_type) { 304 case PT_LOAD: 305 #ifdef CONFIG_X86_64 306 if ((phdr->p_align % 0x200000) != 0) 307 error("Alignment of LOAD segment isn't multiple of 2MB"); 308 #endif 309 #ifdef CONFIG_RELOCATABLE 310 dest = output; 311 dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR); 312 #else 313 dest = (void *)(phdr->p_paddr); 314 #endif 315 memmove(dest, output + phdr->p_offset, phdr->p_filesz); 316 break; 317 default: /* Ignore other PT_* */ break; 318 } 319 } 320 321 free(phdrs); 322 } 323 324 /* 325 * The compressed kernel image (ZO), has been moved so that its position 326 * is against the end of the buffer used to hold the uncompressed kernel 327 * image (VO) and the execution environment (.bss, .brk), which makes sure 328 * there is room to do the in-place decompression. (See header.S for the 329 * calculations.) 330 * 331 * |-----compressed kernel image------| 332 * V V 333 * 0 extract_offset +INIT_SIZE 334 * |-----------|---------------|-------------------------|--------| 335 * | | | | 336 * VO__text startup_32 of ZO VO__end ZO__end 337 * ^ ^ 338 * |-------uncompressed kernel image---------| 339 * 340 */ 341 asmlinkage __visible void *extract_kernel(void *rmode, memptr heap, 342 unsigned char *input_data, 343 unsigned long input_len, 344 unsigned char *output, 345 unsigned long output_len) 346 { 347 const unsigned long kernel_total_size = VO__end - VO__text; 348 unsigned long virt_addr = LOAD_PHYSICAL_ADDR; 349 unsigned long needed_size; 350 351 /* Retain x86 boot parameters pointer passed from startup_32/64. */ 352 boot_params = rmode; 353 354 /* Clear flags intended for solely in-kernel use. */ 355 boot_params->hdr.loadflags &= ~KASLR_FLAG; 356 357 sanitize_boot_params(boot_params); 358 359 if (boot_params->screen_info.orig_video_mode == 7) { 360 vidmem = (char *) 0xb0000; 361 vidport = 0x3b4; 362 } else { 363 vidmem = (char *) 0xb8000; 364 vidport = 0x3d4; 365 } 366 367 lines = boot_params->screen_info.orig_video_lines; 368 cols = boot_params->screen_info.orig_video_cols; 369 370 console_init(); 371 372 /* 373 * Save RSDP address for later use. Have this after console_init() 374 * so that early debugging output from the RSDP parsing code can be 375 * collected. 376 */ 377 boot_params->acpi_rsdp_addr = get_rsdp_addr(); 378 379 debug_putstr("early console in extract_kernel\n"); 380 381 free_mem_ptr = heap; /* Heap */ 382 free_mem_end_ptr = heap + BOOT_HEAP_SIZE; 383 384 /* 385 * The memory hole needed for the kernel is the larger of either 386 * the entire decompressed kernel plus relocation table, or the 387 * entire decompressed kernel plus .bss and .brk sections. 388 * 389 * On X86_64, the memory is mapped with PMD pages. Round the 390 * size up so that the full extent of PMD pages mapped is 391 * included in the check against the valid memory table 392 * entries. This ensures the full mapped area is usable RAM 393 * and doesn't include any reserved areas. 394 */ 395 needed_size = max(output_len, kernel_total_size); 396 #ifdef CONFIG_X86_64 397 needed_size = ALIGN(needed_size, MIN_KERNEL_ALIGN); 398 #endif 399 400 /* Report initial kernel position details. */ 401 debug_putaddr(input_data); 402 debug_putaddr(input_len); 403 debug_putaddr(output); 404 debug_putaddr(output_len); 405 debug_putaddr(kernel_total_size); 406 debug_putaddr(needed_size); 407 408 #ifdef CONFIG_X86_64 409 /* Report address of 32-bit trampoline */ 410 debug_putaddr(trampoline_32bit); 411 #endif 412 413 choose_random_location((unsigned long)input_data, input_len, 414 (unsigned long *)&output, 415 needed_size, 416 &virt_addr); 417 418 /* Validate memory location choices. */ 419 if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1)) 420 error("Destination physical address inappropriately aligned"); 421 if (virt_addr & (MIN_KERNEL_ALIGN - 1)) 422 error("Destination virtual address inappropriately aligned"); 423 #ifdef CONFIG_X86_64 424 if (heap > 0x3fffffffffffUL) 425 error("Destination address too large"); 426 if (virt_addr + max(output_len, kernel_total_size) > KERNEL_IMAGE_SIZE) 427 error("Destination virtual address is beyond the kernel mapping area"); 428 #else 429 if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff)) 430 error("Destination address too large"); 431 #endif 432 #ifndef CONFIG_RELOCATABLE 433 if (virt_addr != LOAD_PHYSICAL_ADDR) 434 error("Destination virtual address changed when not relocatable"); 435 #endif 436 437 debug_putstr("\nDecompressing Linux... "); 438 __decompress(input_data, input_len, NULL, NULL, output, output_len, 439 NULL, error); 440 parse_elf(output); 441 handle_relocations(output, output_len, virt_addr); 442 debug_putstr("done.\nBooting the kernel.\n"); 443 444 /* Disable exception handling before booting the kernel */ 445 cleanup_exception_handling(); 446 447 return output; 448 } 449 450 void fortify_panic(const char *name) 451 { 452 error("detected buffer overflow"); 453 } 454