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