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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 MAX_VAR_NAME 31
48 #define MAX_NATIVE_VAR_NAME \
49 	(strlen("efi_xxxxxxxx-xxxx-xxxx-xxxxxxxxxxxxxxxx_") + \
50 		(MAX_VAR_NAME * MAX_UTF8_PER_UTF16))
51 
hex(int ch)52 static int hex(int ch)
53 {
54 	if (ch >= 'a' && ch <= 'f')
55 		return ch-'a'+10;
56 	if (ch >= '0' && ch <= '9')
57 		return ch-'0';
58 	if (ch >= 'A' && ch <= 'F')
59 		return ch-'A'+10;
60 	return -1;
61 }
62 
hex2mem(u8 * mem,const char * hexstr,int size)63 static int hex2mem(u8 *mem, const char *hexstr, int size)
64 {
65 	int nibble;
66 	int i;
67 
68 	for (i = 0; i < size; i++) {
69 		if (*hexstr == '\0')
70 			break;
71 
72 		nibble = hex(*hexstr);
73 		if (nibble < 0)
74 			return -1;
75 
76 		*mem = nibble;
77 		hexstr++;
78 
79 		nibble = hex(*hexstr);
80 		if (nibble < 0)
81 			return -1;
82 
83 		*mem = (*mem << 4) | nibble;
84 		hexstr++;
85 		mem++;
86 	}
87 
88 	return i;
89 }
90 
mem2hex(char * hexstr,const u8 * mem,int count)91 static char *mem2hex(char *hexstr, const u8 *mem, int count)
92 {
93 	static const char hexchars[] = "0123456789abcdef";
94 
95 	while (count-- > 0) {
96 		u8 ch = *mem++;
97 		*hexstr++ = hexchars[ch >> 4];
98 		*hexstr++ = hexchars[ch & 0xf];
99 	}
100 
101 	return hexstr;
102 }
103 
efi_to_native(char * native,u16 * variable_name,efi_guid_t * vendor)104 static efi_status_t efi_to_native(char *native, u16 *variable_name,
105 				  efi_guid_t *vendor)
106 {
107 	size_t len;
108 
109 	len = utf16_strlen((u16 *)variable_name);
110 	if (len >= MAX_VAR_NAME)
111 		return EFI_DEVICE_ERROR;
112 
113 	native += sprintf(native, "efi_%pUl_", vendor);
114 	native  = (char *)utf16_to_utf8((u8 *)native, (u16 *)variable_name, len);
115 	*native = '\0';
116 
117 	return EFI_SUCCESS;
118 }
119 
prefix(const char * str,const char * prefix)120 static const char *prefix(const char *str, const char *prefix)
121 {
122 	size_t n = strlen(prefix);
123 	if (!strncmp(prefix, str, n))
124 		return str + n;
125 	return NULL;
126 }
127 
128 /* parse attributes part of variable value, if present: */
parse_attr(const char * str,u32 * attrp)129 static const char *parse_attr(const char *str, u32 *attrp)
130 {
131 	u32 attr = 0;
132 	char sep = '{';
133 
134 	if (*str != '{') {
135 		*attrp = EFI_VARIABLE_BOOTSERVICE_ACCESS;
136 		return str;
137 	}
138 
139 	while (*str == sep) {
140 		const char *s;
141 
142 		str++;
143 
144 		if ((s = prefix(str, "ro"))) {
145 			attr |= READ_ONLY;
146 		} else if ((s = prefix(str, "boot"))) {
147 			attr |= EFI_VARIABLE_BOOTSERVICE_ACCESS;
148 		} else if ((s = prefix(str, "run"))) {
149 			attr |= EFI_VARIABLE_RUNTIME_ACCESS;
150 		} else {
151 			printf("invalid attribute: %s\n", str);
152 			break;
153 		}
154 
155 		str = s;
156 		sep = ',';
157 	}
158 
159 	str++;
160 
161 	*attrp = attr;
162 
163 	return str;
164 }
165 
166 /* http://wiki.phoenix.com/wiki/index.php/EFI_RUNTIME_SERVICES#GetVariable.28.29 */
efi_get_variable(u16 * variable_name,efi_guid_t * vendor,u32 * attributes,efi_uintn_t * data_size,void * data)167 efi_status_t EFIAPI efi_get_variable(u16 *variable_name, efi_guid_t *vendor,
168 				     u32 *attributes, efi_uintn_t *data_size,
169 				     void *data)
170 {
171 	char native_name[MAX_NATIVE_VAR_NAME + 1];
172 	efi_status_t ret;
173 	unsigned long in_size;
174 	const char *val, *s;
175 	u32 attr;
176 
177 	EFI_ENTRY("\"%ls\" %pUl %p %p %p", variable_name, vendor, attributes,
178 		  data_size, data);
179 
180 	if (!variable_name || !vendor || !data_size)
181 		return EFI_EXIT(EFI_INVALID_PARAMETER);
182 
183 	ret = efi_to_native(native_name, variable_name, vendor);
184 	if (ret)
185 		return EFI_EXIT(ret);
186 
187 	debug("%s: get '%s'\n", __func__, native_name);
188 
189 	val = env_get(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 */
efi_get_next_variable_name(efi_uintn_t * variable_name_size,u16 * variable_name,efi_guid_t * vendor)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 */
efi_set_variable(u16 * variable_name,efi_guid_t * vendor,u32 attributes,efi_uintn_t data_size,void * data)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[MAX_NATIVE_VAR_NAME + 1];
260 	efi_status_t ret = EFI_SUCCESS;
261 	char *val, *s;
262 	u32 attr;
263 
264 	EFI_ENTRY("\"%ls\" %pUl %x %zu %p", variable_name, vendor, attributes,
265 		  data_size, data);
266 
267 	if (!variable_name || !vendor)
268 		return EFI_EXIT(EFI_INVALID_PARAMETER);
269 
270 	ret = efi_to_native(native_name, variable_name, vendor);
271 	if (ret)
272 		return EFI_EXIT(ret);
273 
274 #define ACCESS_ATTR (EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_BOOTSERVICE_ACCESS)
275 
276 	if ((data_size == 0) || !(attributes & ACCESS_ATTR)) {
277 		/* delete the variable: */
278 		env_set(native_name, NULL);
279 		return EFI_EXIT(EFI_SUCCESS);
280 	}
281 
282 	val = env_get(native_name);
283 	if (val) {
284 		parse_attr(val, &attr);
285 
286 		if (attr & READ_ONLY)
287 			return EFI_EXIT(EFI_WRITE_PROTECTED);
288 	}
289 
290 	val = malloc(2 * data_size + strlen("{ro,run,boot}(blob)") + 1);
291 	if (!val)
292 		return EFI_EXIT(EFI_OUT_OF_RESOURCES);
293 
294 	s = val;
295 
296 	/* store attributes: */
297 	attributes &= (EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS);
298 	s += sprintf(s, "{");
299 	while (attributes) {
300 		u32 attr = 1 << (ffs(attributes) - 1);
301 
302 		if (attr == EFI_VARIABLE_BOOTSERVICE_ACCESS)
303 			s += sprintf(s, "boot");
304 		else if (attr == EFI_VARIABLE_RUNTIME_ACCESS)
305 			s += sprintf(s, "run");
306 
307 		attributes &= ~attr;
308 		if (attributes)
309 			s += sprintf(s, ",");
310 	}
311 	s += sprintf(s, "}");
312 
313 	/* store payload: */
314 	s += sprintf(s, "(blob)");
315 	s = mem2hex(s, data, data_size);
316 	*s = '\0';
317 
318 	debug("%s: setting: %s=%s\n", __func__, native_name, val);
319 
320 	if (env_set(native_name, val))
321 		ret = EFI_DEVICE_ERROR;
322 
323 	free(val);
324 
325 	return EFI_EXIT(ret);
326 }
327