1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  *  EFI utils
4  *
5  *  Copyright (c) 2017 Rob Clark
6  */
7 
8 #include <malloc.h>
9 #include <charset.h>
10 #include <efi_loader.h>
11 
12 #define READ_ONLY BIT(31)
13 
14 /*
15  * Mapping between EFI variables and u-boot variables:
16  *
17  *   efi_$guid_$varname = {attributes}(type)value
18  *
19  * For example:
20  *
21  *   efi_8be4df61-93ca-11d2-aa0d-00e098032b8c_OsIndicationsSupported=
22  *      "{ro,boot,run}(blob)0000000000000000"
23  *   efi_8be4df61-93ca-11d2-aa0d-00e098032b8c_BootOrder=
24  *      "(blob)00010000"
25  *
26  * The attributes are a comma separated list of these possible
27  * attributes:
28  *
29  *   + ro   - read-only
30  *   + boot - boot-services access
31  *   + run  - runtime access
32  *
33  * NOTE: with current implementation, no variables are available after
34  * ExitBootServices, and all are persisted (if possible).
35  *
36  * If not specified, the attributes default to "{boot}".
37  *
38  * The required type is one of:
39  *
40  *   + utf8 - raw utf8 string
41  *   + blob - arbitrary length hex string
42  *
43  * Maybe a utf16 type would be useful to for a string value to be auto
44  * converted to utf16?
45  */
46 
47 #define PREFIX_LEN (strlen("efi_xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx_"))
48 
49 static int hex(int ch)
50 {
51 	if (ch >= 'a' && ch <= 'f')
52 		return ch-'a'+10;
53 	if (ch >= '0' && ch <= '9')
54 		return ch-'0';
55 	if (ch >= 'A' && ch <= 'F')
56 		return ch-'A'+10;
57 	return -1;
58 }
59 
60 static int hex2mem(u8 *mem, const char *hexstr, int size)
61 {
62 	int nibble;
63 	int i;
64 
65 	for (i = 0; i < size; i++) {
66 		if (*hexstr == '\0')
67 			break;
68 
69 		nibble = hex(*hexstr);
70 		if (nibble < 0)
71 			return -1;
72 
73 		*mem = nibble;
74 		hexstr++;
75 
76 		nibble = hex(*hexstr);
77 		if (nibble < 0)
78 			return -1;
79 
80 		*mem = (*mem << 4) | nibble;
81 		hexstr++;
82 		mem++;
83 	}
84 
85 	return i;
86 }
87 
88 static char *mem2hex(char *hexstr, const u8 *mem, int count)
89 {
90 	static const char hexchars[] = "0123456789abcdef";
91 
92 	while (count-- > 0) {
93 		u8 ch = *mem++;
94 		*hexstr++ = hexchars[ch >> 4];
95 		*hexstr++ = hexchars[ch & 0xf];
96 	}
97 
98 	return hexstr;
99 }
100 
101 static efi_status_t efi_to_native(char **native, const u16 *variable_name,
102 				  efi_guid_t *vendor)
103 {
104 	size_t len;
105 	char *pos;
106 
107 	len = PREFIX_LEN + utf16_utf8_strlen(variable_name) + 1;
108 	*native = malloc(len);
109 	if (!*native)
110 		return EFI_OUT_OF_RESOURCES;
111 
112 	pos = *native;
113 	pos += sprintf(pos, "efi_%pUl_", vendor);
114 	utf16_utf8_strcpy(&pos, variable_name);
115 
116 	return EFI_SUCCESS;
117 }
118 
119 static const char *prefix(const char *str, const char *prefix)
120 {
121 	size_t n = strlen(prefix);
122 	if (!strncmp(prefix, str, n))
123 		return str + n;
124 	return NULL;
125 }
126 
127 /* parse attributes part of variable value, if present: */
128 static const char *parse_attr(const char *str, u32 *attrp)
129 {
130 	u32 attr = 0;
131 	char sep = '{';
132 
133 	if (*str != '{') {
134 		*attrp = EFI_VARIABLE_BOOTSERVICE_ACCESS;
135 		return str;
136 	}
137 
138 	while (*str == sep) {
139 		const char *s;
140 
141 		str++;
142 
143 		if ((s = prefix(str, "ro"))) {
144 			attr |= READ_ONLY;
145 		} else if ((s = prefix(str, "boot"))) {
146 			attr |= EFI_VARIABLE_BOOTSERVICE_ACCESS;
147 		} else if ((s = prefix(str, "run"))) {
148 			attr |= EFI_VARIABLE_RUNTIME_ACCESS;
149 		} else {
150 			printf("invalid attribute: %s\n", str);
151 			break;
152 		}
153 
154 		str = s;
155 		sep = ',';
156 	}
157 
158 	str++;
159 
160 	*attrp = attr;
161 
162 	return str;
163 }
164 
165 /* http://wiki.phoenix.com/wiki/index.php/EFI_RUNTIME_SERVICES#GetVariable.28.29 */
166 efi_status_t EFIAPI efi_get_variable(u16 *variable_name, efi_guid_t *vendor,
167 				     u32 *attributes, efi_uintn_t *data_size,
168 				     void *data)
169 {
170 	char *native_name;
171 	efi_status_t ret;
172 	unsigned long in_size;
173 	const char *val, *s;
174 	u32 attr;
175 
176 	EFI_ENTRY("\"%ls\" %pUl %p %p %p", variable_name, vendor, attributes,
177 		  data_size, data);
178 
179 	if (!variable_name || !vendor || !data_size)
180 		return EFI_EXIT(EFI_INVALID_PARAMETER);
181 
182 	ret = efi_to_native(&native_name, variable_name, vendor);
183 	if (ret)
184 		return EFI_EXIT(ret);
185 
186 	debug("%s: get '%s'\n", __func__, native_name);
187 
188 	val = env_get(native_name);
189 	free(native_name);
190 	if (!val)
191 		return EFI_EXIT(EFI_NOT_FOUND);
192 
193 	val = parse_attr(val, &attr);
194 
195 	in_size = *data_size;
196 
197 	if ((s = prefix(val, "(blob)"))) {
198 		unsigned len = strlen(s);
199 
200 		/* number of hexadecimal digits must be even */
201 		if (len & 1)
202 			return EFI_EXIT(EFI_DEVICE_ERROR);
203 
204 		/* two characters per byte: */
205 		len /= 2;
206 		*data_size = len;
207 
208 		if (in_size < len)
209 			return EFI_EXIT(EFI_BUFFER_TOO_SMALL);
210 
211 		if (!data)
212 			return EFI_EXIT(EFI_INVALID_PARAMETER);
213 
214 		if (hex2mem(data, s, len) != len)
215 			return EFI_EXIT(EFI_DEVICE_ERROR);
216 
217 		debug("%s: got value: \"%s\"\n", __func__, s);
218 	} else if ((s = prefix(val, "(utf8)"))) {
219 		unsigned len = strlen(s) + 1;
220 
221 		*data_size = len;
222 
223 		if (in_size < len)
224 			return EFI_EXIT(EFI_BUFFER_TOO_SMALL);
225 
226 		if (!data)
227 			return EFI_EXIT(EFI_INVALID_PARAMETER);
228 
229 		memcpy(data, s, len);
230 		((char *)data)[len] = '\0';
231 
232 		debug("%s: got value: \"%s\"\n", __func__, (char *)data);
233 	} else {
234 		debug("%s: invalid value: '%s'\n", __func__, val);
235 		return EFI_EXIT(EFI_DEVICE_ERROR);
236 	}
237 
238 	if (attributes)
239 		*attributes = attr & EFI_VARIABLE_MASK;
240 
241 	return EFI_EXIT(EFI_SUCCESS);
242 }
243 
244 /* http://wiki.phoenix.com/wiki/index.php/EFI_RUNTIME_SERVICES#GetNextVariableName.28.29 */
245 efi_status_t EFIAPI efi_get_next_variable_name(efi_uintn_t *variable_name_size,
246 					       u16 *variable_name,
247 					       efi_guid_t *vendor)
248 {
249 	EFI_ENTRY("%p \"%ls\" %pUl", variable_name_size, variable_name, vendor);
250 
251 	return EFI_EXIT(EFI_DEVICE_ERROR);
252 }
253 
254 /* http://wiki.phoenix.com/wiki/index.php/EFI_RUNTIME_SERVICES#SetVariable.28.29 */
255 efi_status_t EFIAPI efi_set_variable(u16 *variable_name, efi_guid_t *vendor,
256 				     u32 attributes, efi_uintn_t data_size,
257 				     void *data)
258 {
259 	char *native_name = NULL, *val = NULL, *s;
260 	efi_status_t ret = EFI_SUCCESS;
261 	u32 attr;
262 
263 	EFI_ENTRY("\"%ls\" %pUl %x %zu %p", variable_name, vendor, attributes,
264 		  data_size, data);
265 
266 	if (!variable_name || !vendor) {
267 		ret = EFI_INVALID_PARAMETER;
268 		goto out;
269 	}
270 
271 	ret = efi_to_native(&native_name, variable_name, vendor);
272 	if (ret)
273 		goto out;
274 
275 #define ACCESS_ATTR (EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_BOOTSERVICE_ACCESS)
276 
277 	if ((data_size == 0) || !(attributes & ACCESS_ATTR)) {
278 		/* delete the variable: */
279 		env_set(native_name, NULL);
280 		ret = EFI_SUCCESS;
281 		goto out;
282 	}
283 
284 	val = env_get(native_name);
285 	if (val) {
286 		parse_attr(val, &attr);
287 
288 		if (attr & READ_ONLY) {
289 			/* We should not free val */
290 			val = NULL;
291 			ret = EFI_WRITE_PROTECTED;
292 			goto out;
293 		}
294 	}
295 
296 	val = malloc(2 * data_size + strlen("{ro,run,boot}(blob)") + 1);
297 	if (!val) {
298 		ret = EFI_OUT_OF_RESOURCES;
299 		goto out;
300 	}
301 
302 	s = val;
303 
304 	/* store attributes: */
305 	attributes &= (EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS);
306 	s += sprintf(s, "{");
307 	while (attributes) {
308 		u32 attr = 1 << (ffs(attributes) - 1);
309 
310 		if (attr == EFI_VARIABLE_BOOTSERVICE_ACCESS)
311 			s += sprintf(s, "boot");
312 		else if (attr == EFI_VARIABLE_RUNTIME_ACCESS)
313 			s += sprintf(s, "run");
314 
315 		attributes &= ~attr;
316 		if (attributes)
317 			s += sprintf(s, ",");
318 	}
319 	s += sprintf(s, "}");
320 
321 	/* store payload: */
322 	s += sprintf(s, "(blob)");
323 	s = mem2hex(s, data, data_size);
324 	*s = '\0';
325 
326 	debug("%s: setting: %s=%s\n", __func__, native_name, val);
327 
328 	if (env_set(native_name, val))
329 		ret = EFI_DEVICE_ERROR;
330 
331 out:
332 	free(native_name);
333 	free(val);
334 
335 	return EFI_EXIT(ret);
336 }
337