1 // SPDX-License-Identifier: (GPL-2.0-or-later OR BSD-2-Clause)
2 /*
3 * libfdt - Flat Device Tree manipulation
4 * Copyright (C) 2006 David Gibson, IBM Corporation.
5 */
6 #include "libfdt_env.h"
7
8 #include <fdt.h>
9 #include <libfdt.h>
10
11 #include "libfdt_internal.h"
12
13 /*
14 * Minimal sanity check for a read-only tree. fdt_ro_probe_() checks
15 * that the given buffer contains what appears to be a flattened
16 * device tree with sane information in its header.
17 */
18 int32_t fdt_ro_probe_(const void *fdt)
19 {
20 uint32_t totalsize = fdt_totalsize(fdt);
21
22 if (can_assume(VALID_DTB))
23 return totalsize;
24
25 /* The device tree must be at an 8-byte aligned address */
26 if ((uintptr_t)fdt & 7)
27 return -FDT_ERR_ALIGNMENT;
28
29 if (fdt_magic(fdt) == FDT_MAGIC) {
30 /* Complete tree */
31 if (!can_assume(LATEST)) {
32 if (fdt_version(fdt) < FDT_FIRST_SUPPORTED_VERSION)
33 return -FDT_ERR_BADVERSION;
34 if (fdt_last_comp_version(fdt) >
35 FDT_LAST_SUPPORTED_VERSION)
36 return -FDT_ERR_BADVERSION;
37 }
38 } else if (fdt_magic(fdt) == FDT_SW_MAGIC) {
39 /* Unfinished sequential-write blob */
40 if (!can_assume(VALID_INPUT) && fdt_size_dt_struct(fdt) == 0)
41 return -FDT_ERR_BADSTATE;
42 } else {
43 return -FDT_ERR_BADMAGIC;
44 }
45
46 if (totalsize < INT32_MAX)
47 return totalsize;
48 else
49 return -FDT_ERR_TRUNCATED;
50 }
51
52 static int check_off_(uint32_t hdrsize, uint32_t totalsize, uint32_t off)
53 {
54 return (off >= hdrsize) && (off <= totalsize);
55 }
56
57 static int check_block_(uint32_t hdrsize, uint32_t totalsize,
58 uint32_t base, uint32_t size)
59 {
60 if (!check_off_(hdrsize, totalsize, base))
61 return 0; /* block start out of bounds */
62 if ((base + size) < base)
63 return 0; /* overflow */
64 if (!check_off_(hdrsize, totalsize, base + size))
65 return 0; /* block end out of bounds */
66 return 1;
67 }
68
69 size_t fdt_header_size_(uint32_t version)
70 {
71 if (version <= 1)
72 return FDT_V1_SIZE;
73 else if (version <= 2)
74 return FDT_V2_SIZE;
75 else if (version <= 3)
76 return FDT_V3_SIZE;
77 else if (version <= 16)
78 return FDT_V16_SIZE;
79 else
80 return FDT_V17_SIZE;
81 }
82
83 size_t fdt_header_size(const void *fdt)
84 {
85 return can_assume(LATEST) ? FDT_V17_SIZE :
86 fdt_header_size_(fdt_version(fdt));
87 }
88
89 int fdt_check_header(const void *fdt)
90 {
91 size_t hdrsize;
92
93 /* The device tree must be at an 8-byte aligned address */
94 if ((uintptr_t)fdt & 7)
95 return -FDT_ERR_ALIGNMENT;
96
97 if (fdt_magic(fdt) != FDT_MAGIC)
98 return -FDT_ERR_BADMAGIC;
99 if (!can_assume(LATEST)) {
100 if ((fdt_version(fdt) < FDT_FIRST_SUPPORTED_VERSION)
101 || (fdt_last_comp_version(fdt) >
102 FDT_LAST_SUPPORTED_VERSION))
103 return -FDT_ERR_BADVERSION;
104 if (fdt_version(fdt) < fdt_last_comp_version(fdt))
105 return -FDT_ERR_BADVERSION;
106 }
107 hdrsize = fdt_header_size(fdt);
108 if (!can_assume(VALID_DTB)) {
109 if ((fdt_totalsize(fdt) < hdrsize)
110 || (fdt_totalsize(fdt) > INT_MAX))
111 return -FDT_ERR_TRUNCATED;
112
113 /* Bounds check memrsv block */
114 if (!check_off_(hdrsize, fdt_totalsize(fdt),
115 fdt_off_mem_rsvmap(fdt)))
116 return -FDT_ERR_TRUNCATED;
117
118 /* Bounds check structure block */
119 if (!can_assume(LATEST) && fdt_version(fdt) < 17) {
120 if (!check_off_(hdrsize, fdt_totalsize(fdt),
121 fdt_off_dt_struct(fdt)))
122 return -FDT_ERR_TRUNCATED;
123 } else {
124 if (!check_block_(hdrsize, fdt_totalsize(fdt),
125 fdt_off_dt_struct(fdt),
126 fdt_size_dt_struct(fdt)))
127 return -FDT_ERR_TRUNCATED;
128 }
129
130 /* Bounds check strings block */
131 if (!check_block_(hdrsize, fdt_totalsize(fdt),
132 fdt_off_dt_strings(fdt),
133 fdt_size_dt_strings(fdt)))
134 return -FDT_ERR_TRUNCATED;
135 }
136
137 return 0;
138 }
139
140 const void *fdt_offset_ptr(const void *fdt, int offset, unsigned int len)
141 {
142 unsigned int uoffset = offset;
143 unsigned int absoffset = offset + fdt_off_dt_struct(fdt);
144
145 if (offset < 0)
146 return NULL;
147
148 if (!can_assume(VALID_INPUT))
149 if ((absoffset < uoffset)
150 || ((absoffset + len) < absoffset)
151 || (absoffset + len) > fdt_totalsize(fdt))
152 return NULL;
153
154 if (can_assume(LATEST) || fdt_version(fdt) >= 0x11)
155 if (((uoffset + len) < uoffset)
156 || ((offset + len) > fdt_size_dt_struct(fdt)))
157 return NULL;
158
159 return fdt_offset_ptr_(fdt, offset);
160 }
161
162 uint32_t fdt_next_tag(const void *fdt, int startoffset, int *nextoffset)
163 {
164 const fdt32_t *tagp, *lenp;
165 uint32_t tag, len, sum;
166 int offset = startoffset;
167 const char *p;
168
169 *nextoffset = -FDT_ERR_TRUNCATED;
170 tagp = fdt_offset_ptr(fdt, offset, FDT_TAGSIZE);
171 if (!can_assume(VALID_DTB) && !tagp)
172 return FDT_END; /* premature end */
173 tag = fdt32_to_cpu(*tagp);
174 offset += FDT_TAGSIZE;
175
176 *nextoffset = -FDT_ERR_BADSTRUCTURE;
177 switch (tag) {
178 case FDT_BEGIN_NODE:
179 /* skip name */
180 do {
181 p = fdt_offset_ptr(fdt, offset++, 1);
182 } while (p && (*p != '\0'));
183 if (!can_assume(VALID_DTB) && !p)
184 return FDT_END; /* premature end */
185 break;
186
187 case FDT_PROP:
188 lenp = fdt_offset_ptr(fdt, offset, sizeof(*lenp));
189 if (!can_assume(VALID_DTB) && !lenp)
190 return FDT_END; /* premature end */
191
192 len = fdt32_to_cpu(*lenp);
193 sum = len + offset;
194 if (!can_assume(VALID_DTB) &&
195 (INT_MAX <= sum || sum < (uint32_t) offset))
196 return FDT_END; /* premature end */
197
198 /* skip-name offset, length and value */
199 offset += sizeof(struct fdt_property) - FDT_TAGSIZE + len;
200
201 if (!can_assume(LATEST) &&
202 fdt_version(fdt) < 0x10 && len >= 8 &&
203 ((offset - len) % 8) != 0)
204 offset += 4;
205 break;
206
207 case FDT_END:
208 case FDT_END_NODE:
209 case FDT_NOP:
210 break;
211
212 default:
213 return FDT_END;
214 }
215
216 if (!fdt_offset_ptr(fdt, startoffset, offset - startoffset))
217 return FDT_END; /* premature end */
218
219 *nextoffset = FDT_TAGALIGN(offset);
220 return tag;
221 }
222
223 int fdt_check_node_offset_(const void *fdt, int offset)
224 {
225 if (!can_assume(VALID_INPUT)
226 && ((offset < 0) || (offset % FDT_TAGSIZE)))
227 return -FDT_ERR_BADOFFSET;
228
229 if (fdt_next_tag(fdt, offset, &offset) != FDT_BEGIN_NODE)
230 return -FDT_ERR_BADOFFSET;
231
232 return offset;
233 }
234
235 int fdt_check_prop_offset_(const void *fdt, int offset)
236 {
237 if (!can_assume(VALID_INPUT)
238 && ((offset < 0) || (offset % FDT_TAGSIZE)))
239 return -FDT_ERR_BADOFFSET;
240
241 if (fdt_next_tag(fdt, offset, &offset) != FDT_PROP)
242 return -FDT_ERR_BADOFFSET;
243
244 return offset;
245 }
246
247 int fdt_next_node(const void *fdt, int offset, int *depth)
248 {
249 int nextoffset = 0;
250 uint32_t tag;
251
252 if (offset >= 0)
253 if ((nextoffset = fdt_check_node_offset_(fdt, offset)) < 0)
254 return nextoffset;
255
256 do {
257 offset = nextoffset;
258 tag = fdt_next_tag(fdt, offset, &nextoffset);
259
260 switch (tag) {
261 case FDT_PROP:
262 case FDT_NOP:
263 break;
264
265 case FDT_BEGIN_NODE:
266 if (depth)
267 (*depth)++;
268 break;
269
270 case FDT_END_NODE:
271 if (depth && ((--(*depth)) < 0))
272 return nextoffset;
273 break;
274
275 case FDT_END:
276 if ((nextoffset >= 0)
277 || ((nextoffset == -FDT_ERR_TRUNCATED) && !depth))
278 return -FDT_ERR_NOTFOUND;
279 else
280 return nextoffset;
281 }
282 } while (tag != FDT_BEGIN_NODE);
283
284 return offset;
285 }
286
287 int fdt_first_subnode(const void *fdt, int offset)
288 {
289 int depth = 0;
290
291 offset = fdt_next_node(fdt, offset, &depth);
292 if (offset < 0 || depth != 1)
293 return -FDT_ERR_NOTFOUND;
294
295 return offset;
296 }
297
298 int fdt_next_subnode(const void *fdt, int offset)
299 {
300 int depth = 1;
301
302 /*
303 * With respect to the parent, the depth of the next subnode will be
304 * the same as the last.
305 */
306 do {
307 offset = fdt_next_node(fdt, offset, &depth);
308 if (offset < 0 || depth < 1)
309 return -FDT_ERR_NOTFOUND;
310 } while (depth > 1);
311
312 return offset;
313 }
314
315 const char *fdt_find_string_(const char *strtab, int tabsize, const char *s)
316 {
317 int len = strlen(s) + 1;
318 const char *last = strtab + tabsize - len;
319 const char *p;
320
321 for (p = strtab; p <= last; p++)
322 if (memcmp(p, s, len) == 0)
323 return p;
324 return NULL;
325 }
326
327 int fdt_move(const void *fdt, void *buf, int bufsize)
328 {
329 if (!can_assume(VALID_INPUT) && bufsize < 0)
330 return -FDT_ERR_NOSPACE;
331
332 FDT_RO_PROBE(fdt);
333
334 if (fdt_totalsize(fdt) > (unsigned int)bufsize)
335 return -FDT_ERR_NOSPACE;
336
337 memmove(buf, fdt, fdt_totalsize(fdt));
338 return 0;
339 }
340
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