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
