root/arch/x86/boot/compressed/misc.c

DEFINITIONS

1. scroll
2. serial_putchar
3. __putstr
4. __puthex
5. handle_relocations
6. handle_relocations
7. parse_elf
8. extract_kernel
9. fortify_panic

   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  * Use normal definitions of mem*() from string.c. There are already
  34  * included header files which expect a definition of memset() and by
  35  * the time we define memset macro, it is too late.
  36  */
  37 #undef memcpy
  38 #undef memset
  39 #define memzero(s, n)   memset((s), 0, (n))
  40 #define memmove         memmove
  41 
  42 /* Functions used by the included decompressor code below. */
  43 void *memmove(void *dest, const void *src, size_t n);
  44 
  45 /*
  46  * This is set up by the setup-routine at boot-time
  47  */
  48 struct boot_params *boot_params;
  49 
  50 memptr free_mem_ptr;
  51 memptr free_mem_end_ptr;
  52 
  53 static char *vidmem;
  54 static int vidport;
  55 static int lines, cols;
  56 
  57 #ifdef CONFIG_KERNEL_GZIP
  58 #include "../../../../lib/decompress_inflate.c"
  59 #endif
  60 
  61 #ifdef CONFIG_KERNEL_BZIP2
  62 #include "../../../../lib/decompress_bunzip2.c"
  63 #endif
  64 
  65 #ifdef CONFIG_KERNEL_LZMA
  66 #include "../../../../lib/decompress_unlzma.c"
  67 #endif
  68 
  69 #ifdef CONFIG_KERNEL_XZ
  70 #include "../../../../lib/decompress_unxz.c"
  71 #endif
  72 
  73 #ifdef CONFIG_KERNEL_LZO
  74 #include "../../../../lib/decompress_unlzo.c"
  75 #endif
  76 
  77 #ifdef CONFIG_KERNEL_LZ4
  78 #include "../../../../lib/decompress_unlz4.c"
  79 #endif
  80 /*
  81  * NOTE: When adding a new decompressor, please update the analysis in
  82  * ../header.S.
  83  */
  84 
  85 static void scroll(void)
  86 {
  87         int i;
  88 
  89         memmove(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2);
  90         for (i = (lines - 1) * cols * 2; i < lines * cols * 2; i += 2)
  91                 vidmem[i] = ' ';
  92 }
  93 
  94 #define XMTRDY          0x20
  95 
  96 #define TXR             0       /*  Transmit register (WRITE) */
  97 #define LSR             5       /*  Line Status               */
  98 static void serial_putchar(int ch)
  99 {
 100         unsigned timeout = 0xffff;
 101 
 102         while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
 103                 cpu_relax();
 104 
 105         outb(ch, early_serial_base + TXR);
 106 }
 107 
 108 void __putstr(const char *s)
 109 {
 110         int x, y, pos;
 111         char c;
 112 
 113         if (early_serial_base) {
 114                 const char *str = s;
 115                 while (*str) {
 116                         if (*str == '\n')
 117                                 serial_putchar('\r');
 118                         serial_putchar(*str++);
 119                 }
 120         }
 121 
 122         if (lines == 0 || cols == 0)
 123                 return;
 124 
 125         x = boot_params->screen_info.orig_x;
 126         y = boot_params->screen_info.orig_y;
 127 
 128         while ((c = *s++) != '\0') {
 129                 if (c == '\n') {
 130                         x = 0;
 131                         if (++y >= lines) {
 132                                 scroll();
 133                                 y--;
 134                         }
 135                 } else {
 136                         vidmem[(x + cols * y) * 2] = c;
 137                         if (++x >= cols) {
 138                                 x = 0;
 139                                 if (++y >= lines) {
 140                                         scroll();
 141                                         y--;
 142                                 }
 143                         }
 144                 }
 145         }
 146 
 147         boot_params->screen_info.orig_x = x;
 148         boot_params->screen_info.orig_y = y;
 149 
 150         pos = (x + cols * y) * 2;       /* Update cursor position */
 151         outb(14, vidport);
 152         outb(0xff & (pos >> 9), vidport+1);
 153         outb(15, vidport);
 154         outb(0xff & (pos >> 1), vidport+1);
 155 }
 156 
 157 void __puthex(unsigned long value)
 158 {
 159         char alpha[2] = "0";
 160         int bits;
 161 
 162         for (bits = sizeof(value) * 8 - 4; bits >= 0; bits -= 4) {
 163                 unsigned long digit = (value >> bits) & 0xf;
 164 
 165                 if (digit < 0xA)
 166                         alpha[0] = '0' + digit;
 167                 else
 168                         alpha[0] = 'a' + (digit - 0xA);
 169 
 170                 __putstr(alpha);
 171         }
 172 }
 173 
 174 #if CONFIG_X86_NEED_RELOCS
 175 static void handle_relocations(void *output, unsigned long output_len,
 176                                unsigned long virt_addr)
 177 {
 178         int *reloc;
 179         unsigned long delta, map, ptr;
 180         unsigned long min_addr = (unsigned long)output;
 181         unsigned long max_addr = min_addr + (VO___bss_start - VO__text);
 182 
 183         /*
 184          * Calculate the delta between where vmlinux was linked to load
 185          * and where it was actually loaded.
 186          */
 187         delta = min_addr - LOAD_PHYSICAL_ADDR;
 188 
 189         /*
 190          * The kernel contains a table of relocation addresses. Those
 191          * addresses have the final load address of the kernel in virtual
 192          * memory. We are currently working in the self map. So we need to
 193          * create an adjustment for kernel memory addresses to the self map.
 194          * This will involve subtracting out the base address of the kernel.
 195          */
 196         map = delta - __START_KERNEL_map;
 197 
 198         /*
 199          * 32-bit always performs relocations. 64-bit relocations are only
 200          * needed if KASLR has chosen a different starting address offset
 201          * from __START_KERNEL_map.
 202          */
 203         if (IS_ENABLED(CONFIG_X86_64))
 204                 delta = virt_addr - LOAD_PHYSICAL_ADDR;
 205 
 206         if (!delta) {
 207                 debug_putstr("No relocation needed... ");
 208                 return;
 209         }
 210         debug_putstr("Performing relocations... ");
 211 
 212         /*
 213          * Process relocations: 32 bit relocations first then 64 bit after.
 214          * Three sets of binary relocations are added to the end of the kernel
 215          * before compression. Each relocation table entry is the kernel
 216          * address of the location which needs to be updated stored as a
 217          * 32-bit value which is sign extended to 64 bits.
 218          *
 219          * Format is:
 220          *
 221          * kernel bits...
 222          * 0 - zero terminator for 64 bit relocations
 223          * 64 bit relocation repeated
 224          * 0 - zero terminator for inverse 32 bit relocations
 225          * 32 bit inverse relocation repeated
 226          * 0 - zero terminator for 32 bit relocations
 227          * 32 bit relocation repeated
 228          *
 229          * So we work backwards from the end of the decompressed image.
 230          */
 231         for (reloc = output + output_len - sizeof(*reloc); *reloc; reloc--) {
 232                 long extended = *reloc;
 233                 extended += map;
 234 
 235                 ptr = (unsigned long)extended;
 236                 if (ptr < min_addr || ptr > max_addr)
 237                         error("32-bit relocation outside of kernel!\n");
 238 
 239                 *(uint32_t *)ptr += delta;
 240         }
 241 #ifdef CONFIG_X86_64
 242         while (*--reloc) {
 243                 long extended = *reloc;
 244                 extended += map;
 245 
 246                 ptr = (unsigned long)extended;
 247                 if (ptr < min_addr || ptr > max_addr)
 248                         error("inverse 32-bit relocation outside of kernel!\n");
 249 
 250                 *(int32_t *)ptr -= delta;
 251         }
 252         for (reloc--; *reloc; reloc--) {
 253                 long extended = *reloc;
 254                 extended += map;
 255 
 256                 ptr = (unsigned long)extended;
 257                 if (ptr < min_addr || ptr > max_addr)
 258                         error("64-bit relocation outside of kernel!\n");
 259 
 260                 *(uint64_t *)ptr += delta;
 261         }
 262 #endif
 263 }
 264 #else
 265 static inline void handle_relocations(void *output, unsigned long output_len,
 266                                       unsigned long virt_addr)
 267 { }
 268 #endif
 269 
 270 static void parse_elf(void *output)
 271 {
 272 #ifdef CONFIG_X86_64
 273         Elf64_Ehdr ehdr;
 274         Elf64_Phdr *phdrs, *phdr;
 275 #else
 276         Elf32_Ehdr ehdr;
 277         Elf32_Phdr *phdrs, *phdr;
 278 #endif
 279         void *dest;
 280         int i;
 281 
 282         memcpy(&ehdr, output, sizeof(ehdr));
 283         if (ehdr.e_ident[EI_MAG0] != ELFMAG0 ||
 284            ehdr.e_ident[EI_MAG1] != ELFMAG1 ||
 285            ehdr.e_ident[EI_MAG2] != ELFMAG2 ||
 286            ehdr.e_ident[EI_MAG3] != ELFMAG3) {
 287                 error("Kernel is not a valid ELF file");
 288                 return;
 289         }
 290 
 291         debug_putstr("Parsing ELF... ");
 292 
 293         phdrs = malloc(sizeof(*phdrs) * ehdr.e_phnum);
 294         if (!phdrs)
 295                 error("Failed to allocate space for phdrs");
 296 
 297         memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum);
 298 
 299         for (i = 0; i < ehdr.e_phnum; i++) {
 300                 phdr = &phdrs[i];
 301 
 302                 switch (phdr->p_type) {
 303                 case PT_LOAD:
 304 #ifdef CONFIG_X86_64
 305                         if ((phdr->p_align % 0x200000) != 0)
 306                                 error("Alignment of LOAD segment isn't multiple of 2MB");
 307 #endif
 308 #ifdef CONFIG_RELOCATABLE
 309                         dest = output;
 310                         dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR);
 311 #else
 312                         dest = (void *)(phdr->p_paddr);
 313 #endif
 314                         memmove(dest, output + phdr->p_offset, phdr->p_filesz);
 315                         break;
 316                 default: /* Ignore other PT_* */ break;
 317                 }
 318         }
 319 
 320         free(phdrs);
 321 }
 322 
 323 /*
 324  * The compressed kernel image (ZO), has been moved so that its position
 325  * is against the end of the buffer used to hold the uncompressed kernel
 326  * image (VO) and the execution environment (.bss, .brk), which makes sure
 327  * there is room to do the in-place decompression. (See header.S for the
 328  * calculations.)
 329  *
 330  *                             |-----compressed kernel image------|
 331  *                             V                                  V
 332  * 0                       extract_offset                      +INIT_SIZE
 333  * |-----------|---------------|-------------------------|--------|
 334  *             |               |                         |        |
 335  *           VO__text      startup_32 of ZO          VO__end    ZO__end
 336  *             ^                                         ^
 337  *             |-------uncompressed kernel image---------|
 338  *
 339  */
 340 asmlinkage __visible void *extract_kernel(void *rmode, memptr heap,
 341                                   unsigned char *input_data,
 342                                   unsigned long input_len,
 343                                   unsigned char *output,
 344                                   unsigned long output_len)
 345 {
 346         const unsigned long kernel_total_size = VO__end - VO__text;
 347         unsigned long virt_addr = LOAD_PHYSICAL_ADDR;
 348         unsigned long needed_size;
 349 
 350         /* Retain x86 boot parameters pointer passed from startup_32/64. */
 351         boot_params = rmode;
 352 
 353         /* Clear flags intended for solely in-kernel use. */
 354         boot_params->hdr.loadflags &= ~KASLR_FLAG;
 355 
 356         sanitize_boot_params(boot_params);
 357 
 358         if (boot_params->screen_info.orig_video_mode == 7) {
 359                 vidmem = (char *) 0xb0000;
 360                 vidport = 0x3b4;
 361         } else {
 362                 vidmem = (char *) 0xb8000;
 363                 vidport = 0x3d4;
 364         }
 365 
 366         lines = boot_params->screen_info.orig_video_lines;
 367         cols = boot_params->screen_info.orig_video_cols;
 368 
 369         console_init();
 370 
 371         /*
 372          * Save RSDP address for later use. Have this after console_init()
 373          * so that early debugging output from the RSDP parsing code can be
 374          * collected.
 375          */
 376         boot_params->acpi_rsdp_addr = get_rsdp_addr();
 377 
 378         debug_putstr("early console in extract_kernel\n");
 379 
 380         free_mem_ptr     = heap;        /* Heap */
 381         free_mem_end_ptr = heap + BOOT_HEAP_SIZE;
 382 
 383         /*
 384          * The memory hole needed for the kernel is the larger of either
 385          * the entire decompressed kernel plus relocation table, or the
 386          * entire decompressed kernel plus .bss and .brk sections.
 387          *
 388          * On X86_64, the memory is mapped with PMD pages. Round the
 389          * size up so that the full extent of PMD pages mapped is
 390          * included in the check against the valid memory table
 391          * entries. This ensures the full mapped area is usable RAM
 392          * and doesn't include any reserved areas.
 393          */
 394         needed_size = max(output_len, kernel_total_size);
 395 #ifdef CONFIG_X86_64
 396         needed_size = ALIGN(needed_size, MIN_KERNEL_ALIGN);
 397 #endif
 398 
 399         /* Report initial kernel position details. */
 400         debug_putaddr(input_data);
 401         debug_putaddr(input_len);
 402         debug_putaddr(output);
 403         debug_putaddr(output_len);
 404         debug_putaddr(kernel_total_size);
 405         debug_putaddr(needed_size);
 406 
 407 #ifdef CONFIG_X86_64
 408         /* Report address of 32-bit trampoline */
 409         debug_putaddr(trampoline_32bit);
 410 #endif
 411 
 412         choose_random_location((unsigned long)input_data, input_len,
 413                                 (unsigned long *)&output,
 414                                 needed_size,
 415                                 &virt_addr);
 416 
 417         /* Validate memory location choices. */
 418         if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1))
 419                 error("Destination physical address inappropriately aligned");
 420         if (virt_addr & (MIN_KERNEL_ALIGN - 1))
 421                 error("Destination virtual address inappropriately aligned");
 422 #ifdef CONFIG_X86_64
 423         if (heap > 0x3fffffffffffUL)
 424                 error("Destination address too large");
 425         if (virt_addr + max(output_len, kernel_total_size) > KERNEL_IMAGE_SIZE)
 426                 error("Destination virtual address is beyond the kernel mapping area");
 427 #else
 428         if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff))
 429                 error("Destination address too large");
 430 #endif
 431 #ifndef CONFIG_RELOCATABLE
 432         if ((unsigned long)output != LOAD_PHYSICAL_ADDR)
 433                 error("Destination address does not match LOAD_PHYSICAL_ADDR");
 434         if (virt_addr != LOAD_PHYSICAL_ADDR)
 435                 error("Destination virtual address changed when not relocatable");
 436 #endif
 437 
 438         debug_putstr("\nDecompressing Linux... ");
 439         __decompress(input_data, input_len, NULL, NULL, output, output_len,
 440                         NULL, error);
 441         parse_elf(output);
 442         handle_relocations(output, output_len, virt_addr);
 443         debug_putstr("done.\nBooting the kernel.\n");
 444         return output;
 445 }
 446 
 447 void fortify_panic(const char *name)
 448 {
 449         error("detected buffer overflow");
 450 }