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 /* Define an externally visible malloc()/free(). */
32 #define MALLOC_VISIBLE
33 #include <linux/decompress/mm.h>
34
35 /*
36 * Provide definitions of memzero and memmove as some of the decompressors will
37 * try to define their own functions if these are not defined as macros.
38 */
39 #define memzero(s, n) memset((s), 0, (n))
40 #ifndef memmove
41 #define memmove memmove
42 /* Functions used by the included decompressor code below. */
43 void *memmove(void *dest, const void *src, size_t n);
44 #endif
45
46 /*
47 * This is set up by the setup-routine at boot-time
48 */
49 struct boot_params *boot_params;
50
51 struct port_io_ops pio_ops;
52
53 memptr free_mem_ptr;
54 memptr free_mem_end_ptr;
55
56 static char *vidmem;
57 static int vidport;
58
59 /* These might be accessed before .bss is cleared, so use .data instead. */
60 static int lines __section(".data");
61 static int cols __section(".data");
62
63 #ifdef CONFIG_KERNEL_GZIP
64 #include "../../../../lib/decompress_inflate.c"
65 #endif
66
67 #ifdef CONFIG_KERNEL_BZIP2
68 #include "../../../../lib/decompress_bunzip2.c"
69 #endif
70
71 #ifdef CONFIG_KERNEL_LZMA
72 #include "../../../../lib/decompress_unlzma.c"
73 #endif
74
75 #ifdef CONFIG_KERNEL_XZ
76 #include "../../../../lib/decompress_unxz.c"
77 #endif
78
79 #ifdef CONFIG_KERNEL_LZO
80 #include "../../../../lib/decompress_unlzo.c"
81 #endif
82
83 #ifdef CONFIG_KERNEL_LZ4
84 #include "../../../../lib/decompress_unlz4.c"
85 #endif
86
87 #ifdef CONFIG_KERNEL_ZSTD
88 #include "../../../../lib/decompress_unzstd.c"
89 #endif
90 /*
91 * NOTE: When adding a new decompressor, please update the analysis in
92 * ../header.S.
93 */
94
scroll(void)95 static void scroll(void)
96 {
97 int i;
98
99 memmove(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2);
100 for (i = (lines - 1) * cols * 2; i < lines * cols * 2; i += 2)
101 vidmem[i] = ' ';
102 }
103
104 #define XMTRDY 0x20
105
106 #define TXR 0 /* Transmit register (WRITE) */
107 #define LSR 5 /* Line Status */
serial_putchar(int ch)108 static void serial_putchar(int ch)
109 {
110 unsigned timeout = 0xffff;
111
112 while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
113 cpu_relax();
114
115 outb(ch, early_serial_base + TXR);
116 }
117
__putstr(const char * s)118 void __putstr(const char *s)
119 {
120 int x, y, pos;
121 char c;
122
123 if (early_serial_base) {
124 const char *str = s;
125 while (*str) {
126 if (*str == '\n')
127 serial_putchar('\r');
128 serial_putchar(*str++);
129 }
130 }
131
132 if (lines == 0 || cols == 0)
133 return;
134
135 x = boot_params->screen_info.orig_x;
136 y = boot_params->screen_info.orig_y;
137
138 while ((c = *s++) != '\0') {
139 if (c == '\n') {
140 x = 0;
141 if (++y >= lines) {
142 scroll();
143 y--;
144 }
145 } else {
146 vidmem[(x + cols * y) * 2] = c;
147 if (++x >= cols) {
148 x = 0;
149 if (++y >= lines) {
150 scroll();
151 y--;
152 }
153 }
154 }
155 }
156
157 boot_params->screen_info.orig_x = x;
158 boot_params->screen_info.orig_y = y;
159
160 pos = (x + cols * y) * 2; /* Update cursor position */
161 outb(14, vidport);
162 outb(0xff & (pos >> 9), vidport+1);
163 outb(15, vidport);
164 outb(0xff & (pos >> 1), vidport+1);
165 }
166
__puthex(unsigned long value)167 void __puthex(unsigned long value)
168 {
169 char alpha[2] = "0";
170 int bits;
171
172 for (bits = sizeof(value) * 8 - 4; bits >= 0; bits -= 4) {
173 unsigned long digit = (value >> bits) & 0xf;
174
175 if (digit < 0xA)
176 alpha[0] = '0' + digit;
177 else
178 alpha[0] = 'a' + (digit - 0xA);
179
180 __putstr(alpha);
181 }
182 }
183
184 #ifdef CONFIG_X86_NEED_RELOCS
handle_relocations(void * output,unsigned long output_len,unsigned long virt_addr)185 static void handle_relocations(void *output, unsigned long output_len,
186 unsigned long virt_addr)
187 {
188 int *reloc;
189 unsigned long delta, map, ptr;
190 unsigned long min_addr = (unsigned long)output;
191 unsigned long max_addr = min_addr + (VO___bss_start - VO__text);
192
193 /*
194 * Calculate the delta between where vmlinux was linked to load
195 * and where it was actually loaded.
196 */
197 delta = min_addr - LOAD_PHYSICAL_ADDR;
198
199 /*
200 * The kernel contains a table of relocation addresses. Those
201 * addresses have the final load address of the kernel in virtual
202 * memory. We are currently working in the self map. So we need to
203 * create an adjustment for kernel memory addresses to the self map.
204 * This will involve subtracting out the base address of the kernel.
205 */
206 map = delta - __START_KERNEL_map;
207
208 /*
209 * 32-bit always performs relocations. 64-bit relocations are only
210 * needed if KASLR has chosen a different starting address offset
211 * from __START_KERNEL_map.
212 */
213 if (IS_ENABLED(CONFIG_X86_64))
214 delta = virt_addr - LOAD_PHYSICAL_ADDR;
215
216 if (!delta) {
217 debug_putstr("No relocation needed... ");
218 return;
219 }
220 debug_putstr("Performing relocations... ");
221
222 /*
223 * Process relocations: 32 bit relocations first then 64 bit after.
224 * Three sets of binary relocations are added to the end of the kernel
225 * before compression. Each relocation table entry is the kernel
226 * address of the location which needs to be updated stored as a
227 * 32-bit value which is sign extended to 64 bits.
228 *
229 * Format is:
230 *
231 * kernel bits...
232 * 0 - zero terminator for 64 bit relocations
233 * 64 bit relocation repeated
234 * 0 - zero terminator for inverse 32 bit relocations
235 * 32 bit inverse relocation repeated
236 * 0 - zero terminator for 32 bit relocations
237 * 32 bit relocation repeated
238 *
239 * So we work backwards from the end of the decompressed image.
240 */
241 for (reloc = output + output_len - sizeof(*reloc); *reloc; reloc--) {
242 long extended = *reloc;
243 extended += map;
244
245 ptr = (unsigned long)extended;
246 if (ptr < min_addr || ptr > max_addr)
247 error("32-bit relocation outside of kernel!\n");
248
249 *(uint32_t *)ptr += delta;
250 }
251 #ifdef CONFIG_X86_64
252 while (*--reloc) {
253 long extended = *reloc;
254 extended += map;
255
256 ptr = (unsigned long)extended;
257 if (ptr < min_addr || ptr > max_addr)
258 error("inverse 32-bit relocation outside of kernel!\n");
259
260 *(int32_t *)ptr -= delta;
261 }
262 for (reloc--; *reloc; reloc--) {
263 long extended = *reloc;
264 extended += map;
265
266 ptr = (unsigned long)extended;
267 if (ptr < min_addr || ptr > max_addr)
268 error("64-bit relocation outside of kernel!\n");
269
270 *(uint64_t *)ptr += delta;
271 }
272 #endif
273 }
274 #else
handle_relocations(void * output,unsigned long output_len,unsigned long virt_addr)275 static inline void handle_relocations(void *output, unsigned long output_len,
276 unsigned long virt_addr)
277 { }
278 #endif
279
parse_elf(void * output)280 static size_t parse_elf(void *output)
281 {
282 #ifdef CONFIG_X86_64
283 Elf64_Ehdr ehdr;
284 Elf64_Phdr *phdrs, *phdr;
285 #else
286 Elf32_Ehdr ehdr;
287 Elf32_Phdr *phdrs, *phdr;
288 #endif
289 void *dest;
290 int i;
291
292 memcpy(&ehdr, output, sizeof(ehdr));
293 if (ehdr.e_ident[EI_MAG0] != ELFMAG0 ||
294 ehdr.e_ident[EI_MAG1] != ELFMAG1 ||
295 ehdr.e_ident[EI_MAG2] != ELFMAG2 ||
296 ehdr.e_ident[EI_MAG3] != ELFMAG3)
297 error("Kernel is not a valid ELF file");
298
299 debug_putstr("Parsing ELF... ");
300
301 phdrs = malloc(sizeof(*phdrs) * ehdr.e_phnum);
302 if (!phdrs)
303 error("Failed to allocate space for phdrs");
304
305 memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum);
306
307 for (i = 0; i < ehdr.e_phnum; i++) {
308 phdr = &phdrs[i];
309
310 switch (phdr->p_type) {
311 case PT_LOAD:
312 #ifdef CONFIG_X86_64
313 if ((phdr->p_align % 0x200000) != 0)
314 error("Alignment of LOAD segment isn't multiple of 2MB");
315 #endif
316 #ifdef CONFIG_RELOCATABLE
317 dest = output;
318 dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR);
319 #else
320 dest = (void *)(phdr->p_paddr);
321 #endif
322 memmove(dest, output + phdr->p_offset, phdr->p_filesz);
323 break;
324 default: /* Ignore other PT_* */ break;
325 }
326 }
327
328 free(phdrs);
329
330 return ehdr.e_entry - LOAD_PHYSICAL_ADDR;
331 }
332
333 const unsigned long kernel_text_size = VO___start_rodata - VO__text;
334 const unsigned long kernel_total_size = VO__end - VO__text;
335
336 static u8 boot_heap[BOOT_HEAP_SIZE] __aligned(4);
337
338 extern unsigned char input_data[];
339 extern unsigned int input_len, output_len;
340
decompress_kernel(unsigned char * outbuf,unsigned long virt_addr,void (* error)(char * x))341 unsigned long decompress_kernel(unsigned char *outbuf, unsigned long virt_addr,
342 void (*error)(char *x))
343 {
344 unsigned long entry;
345
346 if (!free_mem_ptr) {
347 free_mem_ptr = (unsigned long)boot_heap;
348 free_mem_end_ptr = (unsigned long)boot_heap + sizeof(boot_heap);
349 }
350
351 if (__decompress(input_data, input_len, NULL, NULL, outbuf, output_len,
352 NULL, error) < 0)
353 return ULONG_MAX;
354
355 entry = parse_elf(outbuf);
356 handle_relocations(outbuf, output_len, virt_addr);
357
358 return entry;
359 }
360
361 /*
362 * Set the memory encryption xloadflag based on the mem_encrypt= command line
363 * parameter, if provided.
364 */
parse_mem_encrypt(struct setup_header * hdr)365 static void parse_mem_encrypt(struct setup_header *hdr)
366 {
367 int on = cmdline_find_option_bool("mem_encrypt=on");
368 int off = cmdline_find_option_bool("mem_encrypt=off");
369
370 if (on > off)
371 hdr->xloadflags |= XLF_MEM_ENCRYPTION;
372 }
373
374 /*
375 * The compressed kernel image (ZO), has been moved so that its position
376 * is against the end of the buffer used to hold the uncompressed kernel
377 * image (VO) and the execution environment (.bss, .brk), which makes sure
378 * there is room to do the in-place decompression. (See header.S for the
379 * calculations.)
380 *
381 * |-----compressed kernel image------|
382 * V V
383 * 0 extract_offset +INIT_SIZE
384 * |-----------|---------------|-------------------------|--------|
385 * | | | |
386 * VO__text startup_32 of ZO VO__end ZO__end
387 * ^ ^
388 * |-------uncompressed kernel image---------|
389 *
390 */
extract_kernel(void * rmode,unsigned char * output)391 asmlinkage __visible void *extract_kernel(void *rmode, unsigned char *output)
392 {
393 unsigned long virt_addr = LOAD_PHYSICAL_ADDR;
394 memptr heap = (memptr)boot_heap;
395 unsigned long needed_size;
396 size_t entry_offset;
397
398 /* Retain x86 boot parameters pointer passed from startup_32/64. */
399 boot_params = rmode;
400
401 /* Clear flags intended for solely in-kernel use. */
402 boot_params->hdr.loadflags &= ~KASLR_FLAG;
403
404 parse_mem_encrypt(&boot_params->hdr);
405
406 sanitize_boot_params(boot_params);
407
408 if (boot_params->screen_info.orig_video_mode == 7) {
409 vidmem = (char *) 0xb0000;
410 vidport = 0x3b4;
411 } else {
412 vidmem = (char *) 0xb8000;
413 vidport = 0x3d4;
414 }
415
416 lines = boot_params->screen_info.orig_video_lines;
417 cols = boot_params->screen_info.orig_video_cols;
418
419 init_default_io_ops();
420
421 /*
422 * Detect TDX guest environment.
423 *
424 * It has to be done before console_init() in order to use
425 * paravirtualized port I/O operations if needed.
426 */
427 early_tdx_detect();
428
429 console_init();
430
431 /*
432 * Save RSDP address for later use. Have this after console_init()
433 * so that early debugging output from the RSDP parsing code can be
434 * collected.
435 */
436 boot_params->acpi_rsdp_addr = get_rsdp_addr();
437
438 debug_putstr("early console in extract_kernel\n");
439
440 free_mem_ptr = heap; /* Heap */
441 free_mem_end_ptr = heap + BOOT_HEAP_SIZE;
442
443 /*
444 * The memory hole needed for the kernel is the larger of either
445 * the entire decompressed kernel plus relocation table, or the
446 * entire decompressed kernel plus .bss and .brk sections.
447 *
448 * On X86_64, the memory is mapped with PMD pages. Round the
449 * size up so that the full extent of PMD pages mapped is
450 * included in the check against the valid memory table
451 * entries. This ensures the full mapped area is usable RAM
452 * and doesn't include any reserved areas.
453 */
454 needed_size = max_t(unsigned long, output_len, kernel_total_size);
455 #ifdef CONFIG_X86_64
456 needed_size = ALIGN(needed_size, MIN_KERNEL_ALIGN);
457 #endif
458
459 /* Report initial kernel position details. */
460 debug_putaddr(input_data);
461 debug_putaddr(input_len);
462 debug_putaddr(output);
463 debug_putaddr(output_len);
464 debug_putaddr(kernel_total_size);
465 debug_putaddr(needed_size);
466
467 #ifdef CONFIG_X86_64
468 /* Report address of 32-bit trampoline */
469 debug_putaddr(trampoline_32bit);
470 #endif
471
472 choose_random_location((unsigned long)input_data, input_len,
473 (unsigned long *)&output,
474 needed_size,
475 &virt_addr);
476
477 /* Validate memory location choices. */
478 if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1))
479 error("Destination physical address inappropriately aligned");
480 if (virt_addr & (MIN_KERNEL_ALIGN - 1))
481 error("Destination virtual address inappropriately aligned");
482 #ifdef CONFIG_X86_64
483 if (heap > 0x3fffffffffffUL)
484 error("Destination address too large");
485 if (virt_addr + needed_size > KERNEL_IMAGE_SIZE)
486 error("Destination virtual address is beyond the kernel mapping area");
487 #else
488 if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff))
489 error("Destination address too large");
490 #endif
491 #ifndef CONFIG_RELOCATABLE
492 if (virt_addr != LOAD_PHYSICAL_ADDR)
493 error("Destination virtual address changed when not relocatable");
494 #endif
495
496 debug_putstr("\nDecompressing Linux... ");
497
498 if (init_unaccepted_memory()) {
499 debug_putstr("Accepting memory... ");
500 accept_memory(__pa(output), __pa(output) + needed_size);
501 }
502
503 entry_offset = decompress_kernel(output, virt_addr, error);
504
505 debug_putstr("done.\nBooting the kernel (entry_offset: 0x");
506 debug_puthex(entry_offset);
507 debug_putstr(").\n");
508
509 /* Disable exception handling before booting the kernel */
510 cleanup_exception_handling();
511
512 return output + entry_offset;
513 }
514
fortify_panic(const char * name)515 void fortify_panic(const char *name)
516 {
517 error("detected buffer overflow");
518 }
519