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 <linux/efi.h>
11 #include <asm/efi.h>
12 
13 #include "efistub.h"
14 
15 #define MAX_FILENAME_SIZE	256
16 
17 /*
18  * Some firmware implementations have problems reading files in one go.
19  * A read chunk size of 1MB seems to work for most platforms.
20  *
21  * Unfortunately, reading files in chunks triggers *other* bugs on some
22  * platforms, so we provide a way to disable this workaround, which can
23  * be done by passing "efi=nochunk" on the EFI boot stub command line.
24  *
25  * If you experience issues with initrd images being corrupt it's worth
26  * trying efi=nochunk, but chunking is enabled by default on x86 because
27  * there are far more machines that require the workaround than those that
28  * break with it enabled.
29  */
30 #define EFI_READ_CHUNK_SIZE	SZ_1M
31 
32 struct finfo {
33 	efi_file_info_t info;
34 	efi_char16_t	filename[MAX_FILENAME_SIZE];
35 };
36 
efi_open_file(efi_file_protocol_t * volume,struct finfo * fi,efi_file_protocol_t ** handle,unsigned long * file_size)37 static efi_status_t efi_open_file(efi_file_protocol_t *volume,
38 				  struct finfo *fi,
39 				  efi_file_protocol_t **handle,
40 				  unsigned long *file_size)
41 {
42 	efi_guid_t info_guid = EFI_FILE_INFO_ID;
43 	efi_file_protocol_t *fh;
44 	unsigned long info_sz;
45 	efi_status_t status;
46 	efi_char16_t *c;
47 
48 	/* Replace UNIX dir separators with EFI standard ones */
49 	for (c = fi->filename; *c != L'\0'; c++) {
50 		if (*c == L'/')
51 			*c = L'\\';
52 	}
53 
54 	status = efi_call_proto(volume, open, &fh, fi->filename,
55 				EFI_FILE_MODE_READ, 0);
56 	if (status != EFI_SUCCESS) {
57 		efi_err("Failed to open file: %ls\n", fi->filename);
58 		return status;
59 	}
60 
61 	info_sz = sizeof(struct finfo);
62 	status = efi_call_proto(fh, get_info, &info_guid, &info_sz, fi);
63 	if (status != EFI_SUCCESS) {
64 		efi_err("Failed to get file info\n");
65 		efi_call_proto(fh, close);
66 		return status;
67 	}
68 
69 	*handle = fh;
70 	*file_size = fi->info.file_size;
71 	return EFI_SUCCESS;
72 }
73 
efi_open_volume(efi_loaded_image_t * image,efi_file_protocol_t ** fh)74 static efi_status_t efi_open_volume(efi_loaded_image_t *image,
75 				    efi_file_protocol_t **fh)
76 {
77 	efi_guid_t fs_proto = EFI_FILE_SYSTEM_GUID;
78 	efi_simple_file_system_protocol_t *io;
79 	efi_status_t status;
80 
81 	status = efi_bs_call(handle_protocol, efi_table_attr(image, device_handle),
82 			     &fs_proto, (void **)&io);
83 	if (status != EFI_SUCCESS) {
84 		efi_err("Failed to handle fs_proto\n");
85 		return status;
86 	}
87 
88 	status = efi_call_proto(io, open_volume, fh);
89 	if (status != EFI_SUCCESS)
90 		efi_err("Failed to open volume\n");
91 
92 	return status;
93 }
94 
find_file_option(const efi_char16_t * cmdline,int cmdline_len,const efi_char16_t * prefix,int prefix_size,efi_char16_t * result,int result_len)95 static int find_file_option(const efi_char16_t *cmdline, int cmdline_len,
96 			    const efi_char16_t *prefix, int prefix_size,
97 			    efi_char16_t *result, int result_len)
98 {
99 	int prefix_len = prefix_size / 2;
100 	bool found = false;
101 	int i;
102 
103 	for (i = prefix_len; i < cmdline_len; i++) {
104 		if (!memcmp(&cmdline[i - prefix_len], prefix, prefix_size)) {
105 			found = true;
106 			break;
107 		}
108 	}
109 
110 	if (!found)
111 		return 0;
112 
113 	/* Skip any leading slashes */
114 	while (i < cmdline_len && (cmdline[i] == L'/' || cmdline[i] == L'\\'))
115 		i++;
116 
117 	while (--result_len > 0 && i < cmdline_len) {
118 		efi_char16_t c = cmdline[i++];
119 
120 		if (c == L'\0' || c == L'\n' || c == L' ')
121 			break;
122 		*result++ = c;
123 	}
124 	*result = L'\0';
125 	return i;
126 }
127 
efi_open_device_path(efi_file_protocol_t ** volume,struct finfo * fi)128 static efi_status_t efi_open_device_path(efi_file_protocol_t **volume,
129 					 struct finfo *fi)
130 {
131 	efi_guid_t text_to_dp_guid = EFI_DEVICE_PATH_FROM_TEXT_PROTOCOL_GUID;
132 	static efi_device_path_from_text_protocol_t *text_to_dp = NULL;
133 	efi_guid_t fs_proto = EFI_FILE_SYSTEM_GUID;
134 	efi_device_path_protocol_t *initrd_dp;
135 	efi_simple_file_system_protocol_t *io;
136 	struct efi_file_path_dev_path *fpath;
137 	efi_handle_t handle;
138 	efi_status_t status;
139 
140 	/* See if the text to device path protocol exists */
141 	if (!text_to_dp &&
142 	    efi_bs_call(locate_protocol, &text_to_dp_guid, NULL,
143 			(void **)&text_to_dp) != EFI_SUCCESS)
144 		return EFI_UNSUPPORTED;
145 
146 
147 	/* Convert the filename wide string into a device path */
148 	initrd_dp = efi_fn_call(text_to_dp, convert_text_to_device_path,
149 				fi->filename);
150 
151 	/* Check whether the device path in question implements simple FS */
152 	if ((efi_bs_call(locate_device_path, &fs_proto, &initrd_dp, &handle) ?:
153 	     efi_bs_call(handle_protocol, handle, &fs_proto, (void **)&io))
154 	    != EFI_SUCCESS)
155 		return EFI_NOT_FOUND;
156 
157 	/* Check whether the remaining device path is a file device path */
158 	if (initrd_dp->type != EFI_DEV_MEDIA ||
159 	    initrd_dp->sub_type != EFI_DEV_MEDIA_FILE) {
160 		efi_warn("Unexpected device path node type: (%x, %x)\n",
161 			 initrd_dp->type, initrd_dp->sub_type);
162 		return EFI_LOAD_ERROR;
163 	}
164 
165 	/* Copy the remaining file path into the fi structure */
166 	fpath = (struct efi_file_path_dev_path *)initrd_dp;
167 	memcpy(fi->filename, fpath->filename,
168 	       min(sizeof(fi->filename),
169 		   fpath->header.length - sizeof(fpath->header)));
170 
171 	status = efi_call_proto(io, open_volume, volume);
172 	if (status != EFI_SUCCESS)
173 		efi_err("Failed to open volume\n");
174 
175 	return status;
176 }
177 
178 /*
179  * Check the cmdline for a LILO-style file= arguments.
180  *
181  * We only support loading a file from the same filesystem as
182  * the kernel image.
183  */
handle_cmdline_files(efi_loaded_image_t * image,const efi_char16_t * optstr,int optstr_size,unsigned long soft_limit,unsigned long hard_limit,unsigned long * load_addr,unsigned long * load_size)184 efi_status_t handle_cmdline_files(efi_loaded_image_t *image,
185 				  const efi_char16_t *optstr,
186 				  int optstr_size,
187 				  unsigned long soft_limit,
188 				  unsigned long hard_limit,
189 				  unsigned long *load_addr,
190 				  unsigned long *load_size)
191 {
192 	const efi_char16_t *cmdline = efi_table_attr(image, load_options);
193 	u32 cmdline_len = efi_table_attr(image, load_options_size);
194 	unsigned long efi_chunk_size = ULONG_MAX;
195 	efi_file_protocol_t *volume = NULL;
196 	efi_file_protocol_t *file;
197 	unsigned long alloc_addr;
198 	unsigned long alloc_size;
199 	efi_status_t status;
200 	int offset;
201 
202 	if (!load_addr || !load_size)
203 		return EFI_INVALID_PARAMETER;
204 
205 	efi_apply_loadoptions_quirk((const void **)&cmdline, &cmdline_len);
206 	cmdline_len /= sizeof(*cmdline);
207 
208 	if (IS_ENABLED(CONFIG_X86) && !efi_nochunk)
209 		efi_chunk_size = EFI_READ_CHUNK_SIZE;
210 
211 	alloc_addr = alloc_size = 0;
212 	do {
213 		struct finfo fi;
214 		unsigned long size;
215 		void *addr;
216 
217 		offset = find_file_option(cmdline, cmdline_len,
218 					  optstr, optstr_size,
219 					  fi.filename, ARRAY_SIZE(fi.filename));
220 
221 		if (!offset)
222 			break;
223 
224 		cmdline += offset;
225 		cmdline_len -= offset;
226 
227 		status = efi_open_device_path(&volume, &fi);
228 		if (status == EFI_UNSUPPORTED || status == EFI_NOT_FOUND)
229 			/* try the volume that holds the kernel itself */
230 			status = efi_open_volume(image, &volume);
231 
232 		if (status != EFI_SUCCESS)
233 			goto err_free_alloc;
234 
235 		status = efi_open_file(volume, &fi, &file, &size);
236 		if (status != EFI_SUCCESS)
237 			goto err_close_volume;
238 
239 		/*
240 		 * Check whether the existing allocation can contain the next
241 		 * file. This condition will also trigger naturally during the
242 		 * first (and typically only) iteration of the loop, given that
243 		 * alloc_size == 0 in that case.
244 		 */
245 		if (round_up(alloc_size + size, EFI_ALLOC_ALIGN) >
246 		    round_up(alloc_size, EFI_ALLOC_ALIGN)) {
247 			unsigned long old_addr = alloc_addr;
248 
249 			status = EFI_OUT_OF_RESOURCES;
250 			if (soft_limit < hard_limit)
251 				status = efi_allocate_pages(alloc_size + size,
252 							    &alloc_addr,
253 							    soft_limit);
254 			if (status == EFI_OUT_OF_RESOURCES)
255 				status = efi_allocate_pages(alloc_size + size,
256 							    &alloc_addr,
257 							    hard_limit);
258 			if (status != EFI_SUCCESS) {
259 				efi_err("Failed to allocate memory for files\n");
260 				goto err_close_file;
261 			}
262 
263 			if (old_addr != 0) {
264 				/*
265 				 * This is not the first time we've gone
266 				 * around this loop, and so we are loading
267 				 * multiple files that need to be concatenated
268 				 * and returned in a single buffer.
269 				 */
270 				memcpy((void *)alloc_addr, (void *)old_addr, alloc_size);
271 				efi_free(alloc_size, old_addr);
272 			}
273 		}
274 
275 		addr = (void *)alloc_addr + alloc_size;
276 		alloc_size += size;
277 
278 		while (size) {
279 			unsigned long chunksize = min(size, efi_chunk_size);
280 
281 			status = efi_call_proto(file, read, &chunksize, addr);
282 			if (status != EFI_SUCCESS) {
283 				efi_err("Failed to read file\n");
284 				goto err_close_file;
285 			}
286 			addr += chunksize;
287 			size -= chunksize;
288 		}
289 		efi_call_proto(file, close);
290 		efi_call_proto(volume, close);
291 	} while (offset > 0);
292 
293 	*load_addr = alloc_addr;
294 	*load_size = alloc_size;
295 
296 	if (*load_size == 0)
297 		return EFI_NOT_READY;
298 	return EFI_SUCCESS;
299 
300 err_close_file:
301 	efi_call_proto(file, close);
302 
303 err_close_volume:
304 	efi_call_proto(volume, close);
305 
306 err_free_alloc:
307 	efi_free(alloc_size, alloc_addr);
308 	return status;
309 }
310