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;
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 = strlen(cmdline) + 1;
191 	efi_status_t status;
192 	char *str, *buf;
193 
194 	status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, len, (void **)&buf);
195 	if (status != EFI_SUCCESS)
196 		return status;
197 
198 	str = skip_spaces(memcpy(buf, cmdline, len));
199 
200 	while (*str) {
201 		char *param, *val;
202 
203 		str = next_arg(str, &param, &val);
204 
205 		if (!strcmp(param, "nokaslr")) {
206 			efi_nokaslr = true;
207 		} else if (!strcmp(param, "quiet")) {
208 			efi_loglevel = CONSOLE_LOGLEVEL_QUIET;
209 		} else if (!strcmp(param, "noinitrd")) {
210 			efi_noinitrd = true;
211 		} else if (!strcmp(param, "efi") && val) {
212 			efi_nochunk = parse_option_str(val, "nochunk");
213 			efi_novamap = parse_option_str(val, "novamap");
214 
215 			efi_nosoftreserve = IS_ENABLED(CONFIG_EFI_SOFT_RESERVE) &&
216 					    parse_option_str(val, "nosoftreserve");
217 
218 			if (parse_option_str(val, "disable_early_pci_dma"))
219 				efi_disable_pci_dma = true;
220 			if (parse_option_str(val, "no_disable_early_pci_dma"))
221 				efi_disable_pci_dma = false;
222 			if (parse_option_str(val, "debug"))
223 				efi_loglevel = CONSOLE_LOGLEVEL_DEBUG;
224 		} else if (!strcmp(param, "video") &&
225 			   val && strstarts(val, "efifb:")) {
226 			efi_parse_option_graphics(val + strlen("efifb:"));
227 		}
228 	}
229 	efi_bs_call(free_pool, buf);
230 	return EFI_SUCCESS;
231 }
232 
233 /*
234  * Convert the unicode UEFI command line to ASCII to pass to kernel.
235  * Size of memory allocated return in *cmd_line_len.
236  * Returns NULL on error.
237  */
238 char *efi_convert_cmdline(efi_loaded_image_t *image, int *cmd_line_len)
239 {
240 	const u16 *s2;
241 	unsigned long cmdline_addr = 0;
242 	int options_chars = efi_table_attr(image, load_options_size) / 2;
243 	const u16 *options = efi_table_attr(image, load_options);
244 	int options_bytes = 0, safe_options_bytes = 0;  /* UTF-8 bytes */
245 	bool in_quote = false;
246 	efi_status_t status;
247 
248 	if (options) {
249 		s2 = options;
250 		while (options_bytes < COMMAND_LINE_SIZE && options_chars--) {
251 			u16 c = *s2++;
252 
253 			if (c < 0x80) {
254 				if (c == L'\0' || c == L'\n')
255 					break;
256 				if (c == L'"')
257 					in_quote = !in_quote;
258 				else if (!in_quote && isspace((char)c))
259 					safe_options_bytes = options_bytes;
260 
261 				options_bytes++;
262 				continue;
263 			}
264 
265 			/*
266 			 * Get the number of UTF-8 bytes corresponding to a
267 			 * UTF-16 character.
268 			 * The first part handles everything in the BMP.
269 			 */
270 			options_bytes += 2 + (c >= 0x800);
271 			/*
272 			 * Add one more byte for valid surrogate pairs. Invalid
273 			 * surrogates will be replaced with 0xfffd and take up
274 			 * only 3 bytes.
275 			 */
276 			if ((c & 0xfc00) == 0xd800) {
277 				/*
278 				 * If the very last word is a high surrogate,
279 				 * we must ignore it since we can't access the
280 				 * low surrogate.
281 				 */
282 				if (!options_chars) {
283 					options_bytes -= 3;
284 				} else if ((*s2 & 0xfc00) == 0xdc00) {
285 					options_bytes++;
286 					options_chars--;
287 					s2++;
288 				}
289 			}
290 		}
291 		if (options_bytes >= COMMAND_LINE_SIZE) {
292 			options_bytes = safe_options_bytes;
293 			efi_err("Command line is too long: truncated to %d bytes\n",
294 				options_bytes);
295 		}
296 	}
297 
298 	options_bytes++;	/* NUL termination */
299 
300 	status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, options_bytes,
301 			     (void **)&cmdline_addr);
302 	if (status != EFI_SUCCESS)
303 		return NULL;
304 
305 	snprintf((char *)cmdline_addr, options_bytes, "%.*ls",
306 		 options_bytes - 1, options);
307 
308 	*cmd_line_len = options_bytes;
309 	return (char *)cmdline_addr;
310 }
311 
312 /**
313  * efi_exit_boot_services() - Exit boot services
314  * @handle:	handle of the exiting image
315  * @map:	pointer to receive the memory map
316  * @priv:	argument to be passed to @priv_func
317  * @priv_func:	function to process the memory map before exiting boot services
318  *
319  * Handle calling ExitBootServices according to the requirements set out by the
320  * spec.  Obtains the current memory map, and returns that info after calling
321  * ExitBootServices.  The client must specify a function to perform any
322  * processing of the memory map data prior to ExitBootServices.  A client
323  * specific structure may be passed to the function via priv.  The client
324  * function may be called multiple times.
325  *
326  * Return:	status code
327  */
328 efi_status_t efi_exit_boot_services(void *handle,
329 				    struct efi_boot_memmap *map,
330 				    void *priv,
331 				    efi_exit_boot_map_processing priv_func)
332 {
333 	efi_status_t status;
334 
335 	status = efi_get_memory_map(map);
336 
337 	if (status != EFI_SUCCESS)
338 		goto fail;
339 
340 	status = priv_func(map, priv);
341 	if (status != EFI_SUCCESS)
342 		goto free_map;
343 
344 	if (efi_disable_pci_dma)
345 		efi_pci_disable_bridge_busmaster();
346 
347 	status = efi_bs_call(exit_boot_services, handle, *map->key_ptr);
348 
349 	if (status == EFI_INVALID_PARAMETER) {
350 		/*
351 		 * The memory map changed between efi_get_memory_map() and
352 		 * exit_boot_services().  Per the UEFI Spec v2.6, Section 6.4:
353 		 * EFI_BOOT_SERVICES.ExitBootServices we need to get the
354 		 * updated map, and try again.  The spec implies one retry
355 		 * should be sufficent, which is confirmed against the EDK2
356 		 * implementation.  Per the spec, we can only invoke
357 		 * get_memory_map() and exit_boot_services() - we cannot alloc
358 		 * so efi_get_memory_map() cannot be used, and we must reuse
359 		 * the buffer.  For all practical purposes, the headroom in the
360 		 * buffer should account for any changes in the map so the call
361 		 * to get_memory_map() is expected to succeed here.
362 		 */
363 		*map->map_size = *map->buff_size;
364 		status = efi_bs_call(get_memory_map,
365 				     map->map_size,
366 				     *map->map,
367 				     map->key_ptr,
368 				     map->desc_size,
369 				     map->desc_ver);
370 
371 		/* exit_boot_services() was called, thus cannot free */
372 		if (status != EFI_SUCCESS)
373 			goto fail;
374 
375 		status = priv_func(map, priv);
376 		/* exit_boot_services() was called, thus cannot free */
377 		if (status != EFI_SUCCESS)
378 			goto fail;
379 
380 		status = efi_bs_call(exit_boot_services, handle, *map->key_ptr);
381 	}
382 
383 	/* exit_boot_services() was called, thus cannot free */
384 	if (status != EFI_SUCCESS)
385 		goto fail;
386 
387 	return EFI_SUCCESS;
388 
389 free_map:
390 	efi_bs_call(free_pool, *map->map);
391 fail:
392 	return status;
393 }
394 
395 /**
396  * get_efi_config_table() - retrieve UEFI configuration table
397  * @guid:	GUID of the configuration table to be retrieved
398  * Return:	pointer to the configuration table or NULL
399  */
400 void *get_efi_config_table(efi_guid_t guid)
401 {
402 	unsigned long tables = efi_table_attr(efi_system_table, tables);
403 	int nr_tables = efi_table_attr(efi_system_table, nr_tables);
404 	int i;
405 
406 	for (i = 0; i < nr_tables; i++) {
407 		efi_config_table_t *t = (void *)tables;
408 
409 		if (efi_guidcmp(t->guid, guid) == 0)
410 			return efi_table_attr(t, table);
411 
412 		tables += efi_is_native() ? sizeof(efi_config_table_t)
413 					  : sizeof(efi_config_table_32_t);
414 	}
415 	return NULL;
416 }
417 
418 /*
419  * The LINUX_EFI_INITRD_MEDIA_GUID vendor media device path below provides a way
420  * for the firmware or bootloader to expose the initrd data directly to the stub
421  * via the trivial LoadFile2 protocol, which is defined in the UEFI spec, and is
422  * very easy to implement. It is a simple Linux initrd specific conduit between
423  * kernel and firmware, allowing us to put the EFI stub (being part of the
424  * kernel) in charge of where and when to load the initrd, while leaving it up
425  * to the firmware to decide whether it needs to expose its filesystem hierarchy
426  * via EFI protocols.
427  */
428 static const struct {
429 	struct efi_vendor_dev_path	vendor;
430 	struct efi_generic_dev_path	end;
431 } __packed initrd_dev_path = {
432 	{
433 		{
434 			EFI_DEV_MEDIA,
435 			EFI_DEV_MEDIA_VENDOR,
436 			sizeof(struct efi_vendor_dev_path),
437 		},
438 		LINUX_EFI_INITRD_MEDIA_GUID
439 	}, {
440 		EFI_DEV_END_PATH,
441 		EFI_DEV_END_ENTIRE,
442 		sizeof(struct efi_generic_dev_path)
443 	}
444 };
445 
446 /**
447  * efi_load_initrd_dev_path() - load the initrd from the Linux initrd device path
448  * @load_addr:	pointer to store the address where the initrd was loaded
449  * @load_size:	pointer to store the size of the loaded initrd
450  * @max:	upper limit for the initrd memory allocation
451  *
452  * Return:
453  * * %EFI_SUCCESS if the initrd was loaded successfully, in which
454  *   case @load_addr and @load_size are assigned accordingly
455  * * %EFI_NOT_FOUND if no LoadFile2 protocol exists on the initrd device path
456  * * %EFI_INVALID_PARAMETER if load_addr == NULL or load_size == NULL
457  * * %EFI_OUT_OF_RESOURCES if memory allocation failed
458  * * %EFI_LOAD_ERROR in all other cases
459  */
460 static
461 efi_status_t efi_load_initrd_dev_path(unsigned long *load_addr,
462 				      unsigned long *load_size,
463 				      unsigned long max)
464 {
465 	efi_guid_t lf2_proto_guid = EFI_LOAD_FILE2_PROTOCOL_GUID;
466 	efi_device_path_protocol_t *dp;
467 	efi_load_file2_protocol_t *lf2;
468 	unsigned long initrd_addr;
469 	unsigned long initrd_size;
470 	efi_handle_t handle;
471 	efi_status_t status;
472 
473 	dp = (efi_device_path_protocol_t *)&initrd_dev_path;
474 	status = efi_bs_call(locate_device_path, &lf2_proto_guid, &dp, &handle);
475 	if (status != EFI_SUCCESS)
476 		return status;
477 
478 	status = efi_bs_call(handle_protocol, handle, &lf2_proto_guid,
479 			     (void **)&lf2);
480 	if (status != EFI_SUCCESS)
481 		return status;
482 
483 	status = efi_call_proto(lf2, load_file, dp, false, &initrd_size, NULL);
484 	if (status != EFI_BUFFER_TOO_SMALL)
485 		return EFI_LOAD_ERROR;
486 
487 	status = efi_allocate_pages(initrd_size, &initrd_addr, max);
488 	if (status != EFI_SUCCESS)
489 		return status;
490 
491 	status = efi_call_proto(lf2, load_file, dp, false, &initrd_size,
492 				(void *)initrd_addr);
493 	if (status != EFI_SUCCESS) {
494 		efi_free(initrd_size, initrd_addr);
495 		return EFI_LOAD_ERROR;
496 	}
497 
498 	*load_addr = initrd_addr;
499 	*load_size = initrd_size;
500 	return EFI_SUCCESS;
501 }
502 
503 static
504 efi_status_t efi_load_initrd_cmdline(efi_loaded_image_t *image,
505 				     unsigned long *load_addr,
506 				     unsigned long *load_size,
507 				     unsigned long soft_limit,
508 				     unsigned long hard_limit)
509 {
510 	if (!IS_ENABLED(CONFIG_EFI_GENERIC_STUB_INITRD_CMDLINE_LOADER) ||
511 	    (IS_ENABLED(CONFIG_X86) && (!efi_is_native() || image == NULL))) {
512 		*load_addr = *load_size = 0;
513 		return EFI_SUCCESS;
514 	}
515 
516 	return handle_cmdline_files(image, L"initrd=", sizeof(L"initrd=") - 2,
517 				    soft_limit, hard_limit,
518 				    load_addr, load_size);
519 }
520 
521 /**
522  * efi_load_initrd() - Load initial RAM disk
523  * @image:	EFI loaded image protocol
524  * @load_addr:	pointer to loaded initrd
525  * @load_size:	size of loaded initrd
526  * @soft_limit:	preferred size of allocated memory for loading the initrd
527  * @hard_limit:	minimum size of allocated memory
528  *
529  * Return:	status code
530  */
531 efi_status_t efi_load_initrd(efi_loaded_image_t *image,
532 			     unsigned long *load_addr,
533 			     unsigned long *load_size,
534 			     unsigned long soft_limit,
535 			     unsigned long hard_limit)
536 {
537 	efi_status_t status;
538 
539 	if (!load_addr || !load_size)
540 		return EFI_INVALID_PARAMETER;
541 
542 	status = efi_load_initrd_dev_path(load_addr, load_size, hard_limit);
543 	if (status == EFI_SUCCESS) {
544 		efi_info("Loaded initrd from LINUX_EFI_INITRD_MEDIA_GUID device path\n");
545 	} else if (status == EFI_NOT_FOUND) {
546 		status = efi_load_initrd_cmdline(image, load_addr, load_size,
547 						 soft_limit, hard_limit);
548 		if (status == EFI_SUCCESS && *load_size > 0)
549 			efi_info("Loaded initrd from command line option\n");
550 	}
551 
552 	return status;
553 }
554 
555 /**
556  * efi_wait_for_key() - Wait for key stroke
557  * @usec:	number of microseconds to wait for key stroke
558  * @key:	key entered
559  *
560  * Wait for up to @usec microseconds for a key stroke.
561  *
562  * Return:	status code, EFI_SUCCESS if key received
563  */
564 efi_status_t efi_wait_for_key(unsigned long usec, efi_input_key_t *key)
565 {
566 	efi_event_t events[2], timer;
567 	unsigned long index;
568 	efi_simple_text_input_protocol_t *con_in;
569 	efi_status_t status;
570 
571 	con_in = efi_table_attr(efi_system_table, con_in);
572 	if (!con_in)
573 		return EFI_UNSUPPORTED;
574 	efi_set_event_at(events, 0, efi_table_attr(con_in, wait_for_key));
575 
576 	status = efi_bs_call(create_event, EFI_EVT_TIMER, 0, NULL, NULL, &timer);
577 	if (status != EFI_SUCCESS)
578 		return status;
579 
580 	status = efi_bs_call(set_timer, timer, EfiTimerRelative,
581 			     EFI_100NSEC_PER_USEC * usec);
582 	if (status != EFI_SUCCESS)
583 		return status;
584 	efi_set_event_at(events, 1, timer);
585 
586 	status = efi_bs_call(wait_for_event, 2, events, &index);
587 	if (status == EFI_SUCCESS) {
588 		if (index == 0)
589 			status = efi_call_proto(con_in, read_keystroke, key);
590 		else
591 			status = EFI_TIMEOUT;
592 	}
593 
594 	efi_bs_call(close_event, timer);
595 
596 	return status;
597 }
598