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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 */
18int32_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
52static int check_off_(uint32_t hdrsize, uint32_t totalsize, uint32_t off)
53{
54 return (off >= hdrsize) && (off <= totalsize);
55}
56
57static 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
69size_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
83size_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
89int 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 /* memrsv block must be 8 byte aligned */
114 if (fdt_off_mem_rsvmap(fdt) % sizeof(uint64_t))
115 return -FDT_ERR_ALIGNMENT;
116
117 /* Structure block must be 4 byte aligned */
118 if (fdt_off_dt_struct(fdt) % FDT_TAGSIZE)
119 return -FDT_ERR_ALIGNMENT;
120
121 /* Bounds check memrsv block */
122 if (!check_off_(hdrsize, fdt_totalsize(fdt),
123 fdt_off_mem_rsvmap(fdt)))
124 return -FDT_ERR_TRUNCATED;
125
126 /* Bounds check structure block */
127 if (!can_assume(LATEST) && fdt_version(fdt) < 17) {
128 if (!check_off_(hdrsize, fdt_totalsize(fdt),
129 fdt_off_dt_struct(fdt)))
130 return -FDT_ERR_TRUNCATED;
131 } else {
132 if (!check_block_(hdrsize, fdt_totalsize(fdt),
133 fdt_off_dt_struct(fdt),
134 fdt_size_dt_struct(fdt)))
135 return -FDT_ERR_TRUNCATED;
136 }
137
138 /* Bounds check strings block */
139 if (!check_block_(hdrsize, fdt_totalsize(fdt),
140 fdt_off_dt_strings(fdt),
141 fdt_size_dt_strings(fdt)))
142 return -FDT_ERR_TRUNCATED;
143 }
144
145 return 0;
146}
147
148const void *fdt_offset_ptr(const void *fdt, int offset, unsigned int len)
149{
150 unsigned int uoffset = offset;
151 unsigned int absoffset = offset + fdt_off_dt_struct(fdt);
152
153 if (offset < 0)
154 return NULL;
155
156 if (!can_assume(VALID_INPUT))
157 if ((absoffset < uoffset)
158 || ((absoffset + len) < absoffset)
159 || (absoffset + len) > fdt_totalsize(fdt))
160 return NULL;
161
162 if (can_assume(LATEST) || fdt_version(fdt) >= 0x11)
163 if (((uoffset + len) < uoffset)
164 || ((offset + len) > fdt_size_dt_struct(fdt)))
165 return NULL;
166
167 return fdt_offset_ptr_(fdt, offset);
168}
169
170uint32_t fdt_next_tag(const void *fdt, int startoffset, int *nextoffset)
171{
172 const fdt32_t *tagp, *lenp;
173 uint32_t tag, len, sum;
174 int offset = startoffset;
175 const char *p;
176
177 *nextoffset = -FDT_ERR_TRUNCATED;
178 tagp = fdt_offset_ptr(fdt, offset, FDT_TAGSIZE);
179 if (!can_assume(VALID_DTB) && !tagp)
180 return FDT_END; /* premature end */
181 tag = fdt32_to_cpu(*tagp);
182 offset += FDT_TAGSIZE;
183
184 *nextoffset = -FDT_ERR_BADSTRUCTURE;
185 switch (tag) {
186 case FDT_BEGIN_NODE:
187 /* skip name */
188 do {
189 p = fdt_offset_ptr(fdt, offset++, 1);
190 } while (p && (*p != '\0'));
191 if (!can_assume(VALID_DTB) && !p)
192 return FDT_END; /* premature end */
193 break;
194
195 case FDT_PROP:
196 lenp = fdt_offset_ptr(fdt, offset, sizeof(*lenp));
197 if (!can_assume(VALID_DTB) && !lenp)
198 return FDT_END; /* premature end */
199
200 len = fdt32_to_cpu(*lenp);
201 sum = len + offset;
202 if (!can_assume(VALID_DTB) &&
203 (INT_MAX <= sum || sum < (uint32_t) offset))
204 return FDT_END; /* premature end */
205
206 /* skip-name offset, length and value */
207 offset += sizeof(struct fdt_property) - FDT_TAGSIZE + len;
208
209 if (!can_assume(LATEST) &&
210 fdt_version(fdt) < 0x10 && len >= 8 &&
211 ((offset - len) % 8) != 0)
212 offset += 4;
213 break;
214
215 case FDT_END:
216 case FDT_END_NODE:
217 case FDT_NOP:
218 break;
219
220 default:
221 return FDT_END;
222 }
223
224 if (!fdt_offset_ptr(fdt, startoffset, offset - startoffset))
225 return FDT_END; /* premature end */
226
227 *nextoffset = FDT_TAGALIGN(offset);
228 return tag;
229}
230
231int fdt_check_node_offset_(const void *fdt, int offset)
232{
233 if (!can_assume(VALID_INPUT)
234 && ((offset < 0) || (offset % FDT_TAGSIZE)))
235 return -FDT_ERR_BADOFFSET;
236
237 if (fdt_next_tag(fdt, offset, &offset) != FDT_BEGIN_NODE)
238 return -FDT_ERR_BADOFFSET;
239
240 return offset;
241}
242
243int fdt_check_prop_offset_(const void *fdt, int offset)
244{
245 if (!can_assume(VALID_INPUT)
246 && ((offset < 0) || (offset % FDT_TAGSIZE)))
247 return -FDT_ERR_BADOFFSET;
248
249 if (fdt_next_tag(fdt, offset, &offset) != FDT_PROP)
250 return -FDT_ERR_BADOFFSET;
251
252 return offset;
253}
254
255int fdt_next_node(const void *fdt, int offset, int *depth)
256{
257 int nextoffset = 0;
258 uint32_t tag;
259
260 if (offset >= 0)
261 if ((nextoffset = fdt_check_node_offset_(fdt, offset)) < 0)
262 return nextoffset;
263
264 do {
265 offset = nextoffset;
266 tag = fdt_next_tag(fdt, offset, &nextoffset);
267
268 switch (tag) {
269 case FDT_PROP:
270 case FDT_NOP:
271 break;
272
273 case FDT_BEGIN_NODE:
274 if (depth)
275 (*depth)++;
276 break;
277
278 case FDT_END_NODE:
279 if (depth && ((--(*depth)) < 0))
280 return nextoffset;
281 break;
282
283 case FDT_END:
284 if ((nextoffset >= 0)
285 || ((nextoffset == -FDT_ERR_TRUNCATED) && !depth))
286 return -FDT_ERR_NOTFOUND;
287 else
288 return nextoffset;
289 }
290 } while (tag != FDT_BEGIN_NODE);
291
292 return offset;
293}
294
295int fdt_first_subnode(const void *fdt, int offset)
296{
297 int depth = 0;
298
299 offset = fdt_next_node(fdt, offset, &depth);
300 if (offset < 0 || depth != 1)
301 return -FDT_ERR_NOTFOUND;
302
303 return offset;
304}
305
306int fdt_next_subnode(const void *fdt, int offset)
307{
308 int depth = 1;
309
310 /*
311 * With respect to the parent, the depth of the next subnode will be
312 * the same as the last.
313 */
314 do {
315 offset = fdt_next_node(fdt, offset, &depth);
316 if (offset < 0 || depth < 1)
317 return -FDT_ERR_NOTFOUND;
318 } while (depth > 1);
319
320 return offset;
321}
322
323const char *fdt_find_string_len_(const char *strtab, int tabsize, const char *s,
324 int slen)
325{
326 const char *last = strtab + tabsize - (slen + 1);
327 const char *p;
328
329 for (p = strtab; p <= last; p++)
330 if (memcmp(p, s, slen) == 0 && p[slen] == '\0')
331 return p;
332 return NULL;
333}
334
335int fdt_move(const void *fdt, void *buf, int bufsize)
336{
337 if (!can_assume(VALID_INPUT) && bufsize < 0)
338 return -FDT_ERR_NOSPACE;
339
340 FDT_RO_PROBE(fdt);
341
342 if (fdt_totalsize(fdt) > (unsigned int)bufsize)
343 return -FDT_ERR_NOSPACE;
344
345 memmove(buf, fdt, fdt_totalsize(fdt));
346 return 0;
347}