1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Helper functions used by the EFI stub on multiple
4  * architectures. This should be #included by the EFI stub
5  * implementation files.
6  *
7  * Copyright 2011 Intel Corporation; author Matt Fleming
8  */
9 
10 #include <stdarg.h>
11 
12 #include <linux/ctype.h>
13 #include <linux/efi.h>
14 #include <linux/kernel.h>
15 #include <linux/printk.h> /* For CONSOLE_LOGLEVEL_* */
16 #include <asm/efi.h>
17 #include <asm/setup.h>
18 
19 #include "efistub.h"
20 
21 bool efi_nochunk;
22 bool efi_nokaslr = !IS_ENABLED(CONFIG_RANDOMIZE_BASE);
23 bool efi_noinitrd;
24 int efi_loglevel = CONSOLE_LOGLEVEL_DEFAULT;
25 bool efi_novamap;
26 
27 static bool efi_nosoftreserve;
28 static bool efi_disable_pci_dma = IS_ENABLED(CONFIG_EFI_DISABLE_PCI_DMA);
29 
30 bool __pure __efi_soft_reserve_enabled(void)
31 {
32 	return !efi_nosoftreserve;
33 }
34 
35 /**
36  * efi_char16_puts() - Write a UCS-2 encoded string to the console
37  * @str:	UCS-2 encoded string
38  */
39 void efi_char16_puts(efi_char16_t *str)
40 {
41 	efi_call_proto(efi_table_attr(efi_system_table, con_out),
42 		       output_string, str);
43 }
44 
45 static
46 u32 utf8_to_utf32(const u8 **s8)
47 {
48 	u32 c32;
49 	u8 c0, cx;
50 	size_t clen, i;
51 
52 	c0 = cx = *(*s8)++;
53 	/*
54 	 * The position of the most-significant 0 bit gives us the length of
55 	 * a multi-octet encoding.
56 	 */
57 	for (clen = 0; cx & 0x80; ++clen)
58 		cx <<= 1;
59 	/*
60 	 * If the 0 bit is in position 8, this is a valid single-octet
61 	 * encoding. If the 0 bit is in position 7 or positions 1-3, the
62 	 * encoding is invalid.
63 	 * In either case, we just return the first octet.
64 	 */
65 	if (clen < 2 || clen > 4)
66 		return c0;
67 	/* Get the bits from the first octet. */
68 	c32 = cx >> clen--;
69 	for (i = 0; i < clen; ++i) {
70 		/* Trailing octets must have 10 in most significant bits. */
71 		cx = (*s8)[i] ^ 0x80;
72 		if (cx & 0xc0)
73 			return c0;
74 		c32 = (c32 << 6) | cx;
75 	}
76 	/*
77 	 * Check for validity:
78 	 * - The character must be in the Unicode range.
79 	 * - It must not be a surrogate.
80 	 * - It must be encoded using the correct number of octets.
81 	 */
82 	if (c32 > 0x10ffff ||
83 	    (c32 & 0xf800) == 0xd800 ||
84 	    clen != (c32 >= 0x80) + (c32 >= 0x800) + (c32 >= 0x10000))
85 		return c0;
86 	*s8 += clen;
87 	return c32;
88 }
89 
90 /**
91  * efi_puts() - Write a UTF-8 encoded string to the console
92  * @str:	UTF-8 encoded string
93  */
94 void efi_puts(const char *str)
95 {
96 	efi_char16_t buf[128];
97 	size_t pos = 0, lim = ARRAY_SIZE(buf);
98 	const u8 *s8 = (const u8 *)str;
99 	u32 c32;
100 
101 	while (*s8) {
102 		if (*s8 == '\n')
103 			buf[pos++] = L'\r';
104 		c32 = utf8_to_utf32(&s8);
105 		if (c32 < 0x10000) {
106 			/* Characters in plane 0 use a single word. */
107 			buf[pos++] = c32;
108 		} else {
109 			/*
110 			 * Characters in other planes encode into a surrogate
111 			 * pair.
112 			 */
113 			buf[pos++] = (0xd800 - (0x10000 >> 10)) + (c32 >> 10);
114 			buf[pos++] = 0xdc00 + (c32 & 0x3ff);
115 		}
116 		if (*s8 == '\0' || pos >= lim - 2) {
117 			buf[pos] = L'\0';
118 			efi_char16_puts(buf);
119 			pos = 0;
120 		}
121 	}
122 }
123 
124 /**
125  * efi_printk() - Print a kernel message
126  * @fmt:	format string
127  *
128  * The first letter of the format string is used to determine the logging level
129  * of the message. If the level is less then the current EFI logging level, the
130  * message is suppressed. The message will be truncated to 255 bytes.
131  *
132  * Return:	number of printed characters
133  */
134 int efi_printk(const char *fmt, ...)
135 {
136 	char printf_buf[256];
137 	va_list args;
138 	int printed;
139 	int loglevel = printk_get_level(fmt);
140 
141 	switch (loglevel) {
142 	case '0' ... '9':
143 		loglevel -= '0';
144 		break;
145 	default:
146 		/*
147 		 * Use loglevel -1 for cases where we just want to print to
148 		 * the screen.
149 		 */
150 		loglevel = -1;
151 		break;
152 	}
153 
154 	if (loglevel >= efi_loglevel)
155 		return 0;
156 
157 	if (loglevel >= 0)
158 		efi_puts("EFI stub: ");
159 
160 	fmt = printk_skip_level(fmt);
161 
162 	va_start(args, fmt);
163 	printed = vsnprintf(printf_buf, sizeof(printf_buf), fmt, args);
164 	va_end(args);
165 
166 	efi_puts(printf_buf);
167 	if (printed >= sizeof(printf_buf)) {
168 		efi_puts("[Message truncated]\n");
169 		return -1;
170 	}
171 
172 	return printed;
173 }
174 
175 /**
176  * efi_parse_options() - Parse EFI command line options
177  * @cmdline:	kernel command line
178  *
179  * Parse the ASCII string @cmdline for EFI options, denoted by the efi=
180  * option, e.g. efi=nochunk.
181  *
182  * It should be noted that efi= is parsed in two very different
183  * environments, first in the early boot environment of the EFI boot
184  * stub, and subsequently during the kernel boot.
185  *
186  * Return:	status code
187  */
188 efi_status_t efi_parse_options(char const *cmdline)
189 {
190 	size_t len;
191 	efi_status_t status;
192 	char *str, *buf;
193 
194 	if (!cmdline)
195 		return EFI_SUCCESS;
196 
197 	len = strnlen(cmdline, COMMAND_LINE_SIZE - 1) + 1;
198 	status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, len, (void **)&buf);
199 	if (status != EFI_SUCCESS)
200 		return status;
201 
202 	memcpy(buf, cmdline, len - 1);
203 	buf[len - 1] = '\0';
204 	str = skip_spaces(buf);
205 
206 	while (*str) {
207 		char *param, *val;
208 
209 		str = next_arg(str, &param, &val);
210 		if (!val && !strcmp(param, "--"))
211 			break;
212 
213 		if (!strcmp(param, "nokaslr")) {
214 			efi_nokaslr = true;
215 		} else if (!strcmp(param, "quiet")) {
216 			efi_loglevel = CONSOLE_LOGLEVEL_QUIET;
217 		} else if (!strcmp(param, "noinitrd")) {
218 			efi_noinitrd = true;
219 		} else if (!strcmp(param, "efi") && val) {
220 			efi_nochunk = parse_option_str(val, "nochunk");
221 			efi_novamap = parse_option_str(val, "novamap");
222 
223 			efi_nosoftreserve = IS_ENABLED(CONFIG_EFI_SOFT_RESERVE) &&
224 					    parse_option_str(val, "nosoftreserve");
225 
226 			if (parse_option_str(val, "disable_early_pci_dma"))
227 				efi_disable_pci_dma = true;
228 			if (parse_option_str(val, "no_disable_early_pci_dma"))
229 				efi_disable_pci_dma = false;
230 			if (parse_option_str(val, "debug"))
231 				efi_loglevel = CONSOLE_LOGLEVEL_DEBUG;
232 		} else if (!strcmp(param, "video") &&
233 			   val && strstarts(val, "efifb:")) {
234 			efi_parse_option_graphics(val + strlen("efifb:"));
235 		}
236 	}
237 	efi_bs_call(free_pool, buf);
238 	return EFI_SUCCESS;
239 }
240 
241 /*
242  * Convert the unicode UEFI command line to ASCII to pass to kernel.
243  * Size of memory allocated return in *cmd_line_len.
244  * Returns NULL on error.
245  */
246 char *efi_convert_cmdline(efi_loaded_image_t *image, int *cmd_line_len)
247 {
248 	const u16 *s2;
249 	unsigned long cmdline_addr = 0;
250 	int options_chars = efi_table_attr(image, load_options_size) / 2;
251 	const u16 *options = efi_table_attr(image, load_options);
252 	int options_bytes = 0, safe_options_bytes = 0;  /* UTF-8 bytes */
253 	bool in_quote = false;
254 	efi_status_t status;
255 
256 	if (options) {
257 		s2 = options;
258 		while (options_bytes < COMMAND_LINE_SIZE && options_chars--) {
259 			u16 c = *s2++;
260 
261 			if (c < 0x80) {
262 				if (c == L'\0' || c == L'\n')
263 					break;
264 				if (c == L'"')
265 					in_quote = !in_quote;
266 				else if (!in_quote && isspace((char)c))
267 					safe_options_bytes = options_bytes;
268 
269 				options_bytes++;
270 				continue;
271 			}
272 
273 			/*
274 			 * Get the number of UTF-8 bytes corresponding to a
275 			 * UTF-16 character.
276 			 * The first part handles everything in the BMP.
277 			 */
278 			options_bytes += 2 + (c >= 0x800);
279 			/*
280 			 * Add one more byte for valid surrogate pairs. Invalid
281 			 * surrogates will be replaced with 0xfffd and take up
282 			 * only 3 bytes.
283 			 */
284 			if ((c & 0xfc00) == 0xd800) {
285 				/*
286 				 * If the very last word is a high surrogate,
287 				 * we must ignore it since we can't access the
288 				 * low surrogate.
289 				 */
290 				if (!options_chars) {
291 					options_bytes -= 3;
292 				} else if ((*s2 & 0xfc00) == 0xdc00) {
293 					options_bytes++;
294 					options_chars--;
295 					s2++;
296 				}
297 			}
298 		}
299 		if (options_bytes >= COMMAND_LINE_SIZE) {
300 			options_bytes = safe_options_bytes;
301 			efi_err("Command line is too long: truncated to %d bytes\n",
302 				options_bytes);
303 		}
304 	}
305 
306 	options_bytes++;	/* NUL termination */
307 
308 	status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, options_bytes,
309 			     (void **)&cmdline_addr);
310 	if (status != EFI_SUCCESS)
311 		return NULL;
312 
313 	snprintf((char *)cmdline_addr, options_bytes, "%.*ls",
314 		 options_bytes - 1, options);
315 
316 	*cmd_line_len = options_bytes;
317 	return (char *)cmdline_addr;
318 }
319 
320 /**
321  * efi_exit_boot_services() - Exit boot services
322  * @handle:	handle of the exiting image
323  * @map:	pointer to receive the memory map
324  * @priv:	argument to be passed to @priv_func
325  * @priv_func:	function to process the memory map before exiting boot services
326  *
327  * Handle calling ExitBootServices according to the requirements set out by the
328  * spec.  Obtains the current memory map, and returns that info after calling
329  * ExitBootServices.  The client must specify a function to perform any
330  * processing of the memory map data prior to ExitBootServices.  A client
331  * specific structure may be passed to the function via priv.  The client
332  * function may be called multiple times.
333  *
334  * Return:	status code
335  */
336 efi_status_t efi_exit_boot_services(void *handle,
337 				    struct efi_boot_memmap *map,
338 				    void *priv,
339 				    efi_exit_boot_map_processing priv_func)
340 {
341 	efi_status_t status;
342 
343 	status = efi_get_memory_map(map);
344 
345 	if (status != EFI_SUCCESS)
346 		goto fail;
347 
348 	status = priv_func(map, priv);
349 	if (status != EFI_SUCCESS)
350 		goto free_map;
351 
352 	if (efi_disable_pci_dma)
353 		efi_pci_disable_bridge_busmaster();
354 
355 	status = efi_bs_call(exit_boot_services, handle, *map->key_ptr);
356 
357 	if (status == EFI_INVALID_PARAMETER) {
358 		/*
359 		 * The memory map changed between efi_get_memory_map() and
360 		 * exit_boot_services().  Per the UEFI Spec v2.6, Section 6.4:
361 		 * EFI_BOOT_SERVICES.ExitBootServices we need to get the
362 		 * updated map, and try again.  The spec implies one retry
363 		 * should be sufficent, which is confirmed against the EDK2
364 		 * implementation.  Per the spec, we can only invoke
365 		 * get_memory_map() and exit_boot_services() - we cannot alloc
366 		 * so efi_get_memory_map() cannot be used, and we must reuse
367 		 * the buffer.  For all practical purposes, the headroom in the
368 		 * buffer should account for any changes in the map so the call
369 		 * to get_memory_map() is expected to succeed here.
370 		 */
371 		*map->map_size = *map->buff_size;
372 		status = efi_bs_call(get_memory_map,
373 				     map->map_size,
374 				     *map->map,
375 				     map->key_ptr,
376 				     map->desc_size,
377 				     map->desc_ver);
378 
379 		/* exit_boot_services() was called, thus cannot free */
380 		if (status != EFI_SUCCESS)
381 			goto fail;
382 
383 		status = priv_func(map, priv);
384 		/* exit_boot_services() was called, thus cannot free */
385 		if (status != EFI_SUCCESS)
386 			goto fail;
387 
388 		status = efi_bs_call(exit_boot_services, handle, *map->key_ptr);
389 	}
390 
391 	/* exit_boot_services() was called, thus cannot free */
392 	if (status != EFI_SUCCESS)
393 		goto fail;
394 
395 	return EFI_SUCCESS;
396 
397 free_map:
398 	efi_bs_call(free_pool, *map->map);
399 fail:
400 	return status;
401 }
402 
403 /**
404  * get_efi_config_table() - retrieve UEFI configuration table
405  * @guid:	GUID of the configuration table to be retrieved
406  * Return:	pointer to the configuration table or NULL
407  */
408 void *get_efi_config_table(efi_guid_t guid)
409 {
410 	unsigned long tables = efi_table_attr(efi_system_table, tables);
411 	int nr_tables = efi_table_attr(efi_system_table, nr_tables);
412 	int i;
413 
414 	for (i = 0; i < nr_tables; i++) {
415 		efi_config_table_t *t = (void *)tables;
416 
417 		if (efi_guidcmp(t->guid, guid) == 0)
418 			return efi_table_attr(t, table);
419 
420 		tables += efi_is_native() ? sizeof(efi_config_table_t)
421 					  : sizeof(efi_config_table_32_t);
422 	}
423 	return NULL;
424 }
425 
426 /*
427  * The LINUX_EFI_INITRD_MEDIA_GUID vendor media device path below provides a way
428  * for the firmware or bootloader to expose the initrd data directly to the stub
429  * via the trivial LoadFile2 protocol, which is defined in the UEFI spec, and is
430  * very easy to implement. It is a simple Linux initrd specific conduit between
431  * kernel and firmware, allowing us to put the EFI stub (being part of the
432  * kernel) in charge of where and when to load the initrd, while leaving it up
433  * to the firmware to decide whether it needs to expose its filesystem hierarchy
434  * via EFI protocols.
435  */
436 static const struct {
437 	struct efi_vendor_dev_path	vendor;
438 	struct efi_generic_dev_path	end;
439 } __packed initrd_dev_path = {
440 	{
441 		{
442 			EFI_DEV_MEDIA,
443 			EFI_DEV_MEDIA_VENDOR,
444 			sizeof(struct efi_vendor_dev_path),
445 		},
446 		LINUX_EFI_INITRD_MEDIA_GUID
447 	}, {
448 		EFI_DEV_END_PATH,
449 		EFI_DEV_END_ENTIRE,
450 		sizeof(struct efi_generic_dev_path)
451 	}
452 };
453 
454 /**
455  * efi_load_initrd_dev_path() - load the initrd from the Linux initrd device path
456  * @load_addr:	pointer to store the address where the initrd was loaded
457  * @load_size:	pointer to store the size of the loaded initrd
458  * @max:	upper limit for the initrd memory allocation
459  *
460  * Return:
461  * * %EFI_SUCCESS if the initrd was loaded successfully, in which
462  *   case @load_addr and @load_size are assigned accordingly
463  * * %EFI_NOT_FOUND if no LoadFile2 protocol exists on the initrd device path
464  * * %EFI_INVALID_PARAMETER if load_addr == NULL or load_size == NULL
465  * * %EFI_OUT_OF_RESOURCES if memory allocation failed
466  * * %EFI_LOAD_ERROR in all other cases
467  */
468 static
469 efi_status_t efi_load_initrd_dev_path(unsigned long *load_addr,
470 				      unsigned long *load_size,
471 				      unsigned long max)
472 {
473 	efi_guid_t lf2_proto_guid = EFI_LOAD_FILE2_PROTOCOL_GUID;
474 	efi_device_path_protocol_t *dp;
475 	efi_load_file2_protocol_t *lf2;
476 	unsigned long initrd_addr;
477 	unsigned long initrd_size;
478 	efi_handle_t handle;
479 	efi_status_t status;
480 
481 	dp = (efi_device_path_protocol_t *)&initrd_dev_path;
482 	status = efi_bs_call(locate_device_path, &lf2_proto_guid, &dp, &handle);
483 	if (status != EFI_SUCCESS)
484 		return status;
485 
486 	status = efi_bs_call(handle_protocol, handle, &lf2_proto_guid,
487 			     (void **)&lf2);
488 	if (status != EFI_SUCCESS)
489 		return status;
490 
491 	status = efi_call_proto(lf2, load_file, dp, false, &initrd_size, NULL);
492 	if (status != EFI_BUFFER_TOO_SMALL)
493 		return EFI_LOAD_ERROR;
494 
495 	status = efi_allocate_pages(initrd_size, &initrd_addr, max);
496 	if (status != EFI_SUCCESS)
497 		return status;
498 
499 	status = efi_call_proto(lf2, load_file, dp, false, &initrd_size,
500 				(void *)initrd_addr);
501 	if (status != EFI_SUCCESS) {
502 		efi_free(initrd_size, initrd_addr);
503 		return EFI_LOAD_ERROR;
504 	}
505 
506 	*load_addr = initrd_addr;
507 	*load_size = initrd_size;
508 	return EFI_SUCCESS;
509 }
510 
511 static
512 efi_status_t efi_load_initrd_cmdline(efi_loaded_image_t *image,
513 				     unsigned long *load_addr,
514 				     unsigned long *load_size,
515 				     unsigned long soft_limit,
516 				     unsigned long hard_limit)
517 {
518 	if (!IS_ENABLED(CONFIG_EFI_GENERIC_STUB_INITRD_CMDLINE_LOADER) ||
519 	    (IS_ENABLED(CONFIG_X86) && (!efi_is_native() || image == NULL))) {
520 		*load_addr = *load_size = 0;
521 		return EFI_SUCCESS;
522 	}
523 
524 	return handle_cmdline_files(image, L"initrd=", sizeof(L"initrd=") - 2,
525 				    soft_limit, hard_limit,
526 				    load_addr, load_size);
527 }
528 
529 /**
530  * efi_load_initrd() - Load initial RAM disk
531  * @image:	EFI loaded image protocol
532  * @load_addr:	pointer to loaded initrd
533  * @load_size:	size of loaded initrd
534  * @soft_limit:	preferred size of allocated memory for loading the initrd
535  * @hard_limit:	minimum size of allocated memory
536  *
537  * Return:	status code
538  */
539 efi_status_t efi_load_initrd(efi_loaded_image_t *image,
540 			     unsigned long *load_addr,
541 			     unsigned long *load_size,
542 			     unsigned long soft_limit,
543 			     unsigned long hard_limit)
544 {
545 	efi_status_t status;
546 
547 	if (!load_addr || !load_size)
548 		return EFI_INVALID_PARAMETER;
549 
550 	status = efi_load_initrd_dev_path(load_addr, load_size, hard_limit);
551 	if (status == EFI_SUCCESS) {
552 		efi_info("Loaded initrd from LINUX_EFI_INITRD_MEDIA_GUID device path\n");
553 	} else if (status == EFI_NOT_FOUND) {
554 		status = efi_load_initrd_cmdline(image, load_addr, load_size,
555 						 soft_limit, hard_limit);
556 		if (status == EFI_SUCCESS && *load_size > 0)
557 			efi_info("Loaded initrd from command line option\n");
558 	}
559 
560 	return status;
561 }
562 
563 /**
564  * efi_wait_for_key() - Wait for key stroke
565  * @usec:	number of microseconds to wait for key stroke
566  * @key:	key entered
567  *
568  * Wait for up to @usec microseconds for a key stroke.
569  *
570  * Return:	status code, EFI_SUCCESS if key received
571  */
572 efi_status_t efi_wait_for_key(unsigned long usec, efi_input_key_t *key)
573 {
574 	efi_event_t events[2], timer;
575 	unsigned long index;
576 	efi_simple_text_input_protocol_t *con_in;
577 	efi_status_t status;
578 
579 	con_in = efi_table_attr(efi_system_table, con_in);
580 	if (!con_in)
581 		return EFI_UNSUPPORTED;
582 	efi_set_event_at(events, 0, efi_table_attr(con_in, wait_for_key));
583 
584 	status = efi_bs_call(create_event, EFI_EVT_TIMER, 0, NULL, NULL, &timer);
585 	if (status != EFI_SUCCESS)
586 		return status;
587 
588 	status = efi_bs_call(set_timer, timer, EfiTimerRelative,
589 			     EFI_100NSEC_PER_USEC * usec);
590 	if (status != EFI_SUCCESS)
591 		return status;
592 	efi_set_event_at(events, 1, timer);
593 
594 	status = efi_bs_call(wait_for_event, 2, events, &index);
595 	if (status == EFI_SUCCESS) {
596 		if (index == 0)
597 			status = efi_call_proto(con_in, read_keystroke, key);
598 		else
599 			status = EFI_TIMEOUT;
600 	}
601 
602 	efi_bs_call(close_event, timer);
603 
604 	return status;
605 }
606