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 */
fdt_ro_probe_(const void * fdt)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
check_off_(uint32_t hdrsize,uint32_t totalsize,uint32_t off)52 static int check_off_(uint32_t hdrsize, uint32_t totalsize, uint32_t off)
53 {
54 return (off >= hdrsize) && (off <= totalsize);
55 }
56
check_block_(uint32_t hdrsize,uint32_t totalsize,uint32_t base,uint32_t size)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
fdt_header_size_(uint32_t version)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
fdt_header_size(const void * fdt)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
fdt_check_header(const void * fdt)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
110 if ((fdt_totalsize(fdt) < hdrsize)
111 || (fdt_totalsize(fdt) > INT_MAX))
112 return -FDT_ERR_TRUNCATED;
113
114 /* Bounds check memrsv block */
115 if (!check_off_(hdrsize, fdt_totalsize(fdt),
116 fdt_off_mem_rsvmap(fdt)))
117 return -FDT_ERR_TRUNCATED;
118 }
119
120 if (!can_assume(VALID_DTB)) {
121 /* Bounds check structure block */
122 if (!can_assume(LATEST) && fdt_version(fdt) < 17) {
123 if (!check_off_(hdrsize, fdt_totalsize(fdt),
124 fdt_off_dt_struct(fdt)))
125 return -FDT_ERR_TRUNCATED;
126 } else {
127 if (!check_block_(hdrsize, fdt_totalsize(fdt),
128 fdt_off_dt_struct(fdt),
129 fdt_size_dt_struct(fdt)))
130 return -FDT_ERR_TRUNCATED;
131 }
132
133 /* Bounds check strings block */
134 if (!check_block_(hdrsize, fdt_totalsize(fdt),
135 fdt_off_dt_strings(fdt),
136 fdt_size_dt_strings(fdt)))
137 return -FDT_ERR_TRUNCATED;
138 }
139
140 return 0;
141 }
142
fdt_offset_ptr(const void * fdt,int offset,unsigned int len)143 const void *fdt_offset_ptr(const void *fdt, int offset, unsigned int len)
144 {
145 unsigned int uoffset = offset;
146 unsigned int absoffset = offset + fdt_off_dt_struct(fdt);
147
148 if (offset < 0)
149 return NULL;
150
151 if (!can_assume(VALID_INPUT))
152 if ((absoffset < uoffset)
153 || ((absoffset + len) < absoffset)
154 || (absoffset + len) > fdt_totalsize(fdt))
155 return NULL;
156
157 if (can_assume(LATEST) || fdt_version(fdt) >= 0x11)
158 if (((uoffset + len) < uoffset)
159 || ((offset + len) > fdt_size_dt_struct(fdt)))
160 return NULL;
161
162 return fdt_offset_ptr_(fdt, offset);
163 }
164
fdt_next_tag(const void * fdt,int startoffset,int * nextoffset)165 uint32_t fdt_next_tag(const void *fdt, int startoffset, int *nextoffset)
166 {
167 const fdt32_t *tagp, *lenp;
168 uint32_t tag;
169 int offset = startoffset;
170 const char *p;
171
172 *nextoffset = -FDT_ERR_TRUNCATED;
173 tagp = fdt_offset_ptr(fdt, offset, FDT_TAGSIZE);
174 if (!can_assume(VALID_DTB) && !tagp)
175 return FDT_END; /* premature end */
176 tag = fdt32_to_cpu(*tagp);
177 offset += FDT_TAGSIZE;
178
179 *nextoffset = -FDT_ERR_BADSTRUCTURE;
180 switch (tag) {
181 case FDT_BEGIN_NODE:
182 /* skip name */
183 do {
184 p = fdt_offset_ptr(fdt, offset++, 1);
185 } while (p && (*p != '\0'));
186 if (!can_assume(VALID_DTB) && !p)
187 return FDT_END; /* premature end */
188 break;
189
190 case FDT_PROP:
191 lenp = fdt_offset_ptr(fdt, offset, sizeof(struct fdt_property) - FDT_TAGSIZE);
192 if (!can_assume(VALID_DTB) && !lenp)
193 return FDT_END; /* premature end */
194
195 /* skip name offset, length */
196 offset += sizeof(struct fdt_property) - FDT_TAGSIZE;
197
198 if (!can_assume(VALID_DTB)
199 && !fdt_offset_ptr(fdt, offset, fdt32_to_cpu(*lenp)))
200 return FDT_END; /* premature end */
201
202 /* skip value */
203 offset += fdt32_to_cpu(*lenp);
204
205 if (!can_assume(LATEST) &&
206 fdt_version(fdt) < 0x10 && fdt32_to_cpu(*lenp) >= 8 &&
207 ((offset - fdt32_to_cpu(*lenp)) % 8) != 0)
208 offset += 4;
209 break;
210
211 case FDT_END:
212 case FDT_END_NODE:
213 case FDT_NOP:
214 break;
215
216 default:
217 return FDT_END;
218 }
219
220 if (!can_assume(VALID_DTB) && (offset <= startoffset
221 || !fdt_offset_ptr(fdt, startoffset, offset - startoffset)))
222 return FDT_END; /* premature end */
223
224 *nextoffset = FDT_TAGALIGN(offset);
225 return tag;
226 }
227
fdt_check_node_offset_(const void * fdt,int offset)228 int fdt_check_node_offset_(const void *fdt, int offset)
229 {
230 if (!can_assume(VALID_INPUT)
231 && ((offset < 0) || (offset % FDT_TAGSIZE)))
232 return -FDT_ERR_BADOFFSET;
233
234 if (fdt_next_tag(fdt, offset, &offset) != FDT_BEGIN_NODE)
235 return -FDT_ERR_BADOFFSET;
236
237 return offset;
238 }
239
fdt_check_prop_offset_(const void * fdt,int offset)240 int fdt_check_prop_offset_(const void *fdt, int offset)
241 {
242 if (!can_assume(VALID_INPUT)
243 && ((offset < 0) || (offset % FDT_TAGSIZE)))
244 return -FDT_ERR_BADOFFSET;
245
246 if (fdt_next_tag(fdt, offset, &offset) != FDT_PROP)
247 return -FDT_ERR_BADOFFSET;
248
249 return offset;
250 }
251
fdt_next_node(const void * fdt,int offset,int * depth)252 int fdt_next_node(const void *fdt, int offset, int *depth)
253 {
254 int nextoffset = 0;
255 uint32_t tag;
256
257 if (offset >= 0)
258 if ((nextoffset = fdt_check_node_offset_(fdt, offset)) < 0)
259 return nextoffset;
260
261 do {
262 offset = nextoffset;
263 tag = fdt_next_tag(fdt, offset, &nextoffset);
264
265 switch (tag) {
266 case FDT_PROP:
267 case FDT_NOP:
268 break;
269
270 case FDT_BEGIN_NODE:
271 if (depth)
272 (*depth)++;
273 break;
274
275 case FDT_END_NODE:
276 if (depth && ((--(*depth)) < 0))
277 return nextoffset;
278 break;
279
280 case FDT_END:
281 if ((nextoffset >= 0)
282 || ((nextoffset == -FDT_ERR_TRUNCATED) && !depth))
283 return -FDT_ERR_NOTFOUND;
284 else
285 return nextoffset;
286 }
287 } while (tag != FDT_BEGIN_NODE);
288
289 return offset;
290 }
291
fdt_first_subnode(const void * fdt,int offset)292 int fdt_first_subnode(const void *fdt, int offset)
293 {
294 int depth = 0;
295
296 offset = fdt_next_node(fdt, offset, &depth);
297 if (offset < 0 || depth != 1)
298 return -FDT_ERR_NOTFOUND;
299
300 return offset;
301 }
302
fdt_next_subnode(const void * fdt,int offset)303 int fdt_next_subnode(const void *fdt, int offset)
304 {
305 int depth = 1;
306
307 /*
308 * With respect to the parent, the depth of the next subnode will be
309 * the same as the last.
310 */
311 do {
312 offset = fdt_next_node(fdt, offset, &depth);
313 if (offset < 0 || depth < 1)
314 return -FDT_ERR_NOTFOUND;
315 } while (depth > 1);
316
317 return offset;
318 }
319
fdt_find_string_(const char * strtab,int tabsize,const char * s)320 const char *fdt_find_string_(const char *strtab, int tabsize, const char *s)
321 {
322 int len = strlen(s) + 1;
323 const char *last = strtab + tabsize - len;
324 const char *p;
325
326 for (p = strtab; p <= last; p++)
327 if (memcmp(p, s, len) == 0)
328 return p;
329 return NULL;
330 }
331
fdt_move(const void * fdt,void * buf,int bufsize)332 int fdt_move(const void *fdt, void *buf, int bufsize)
333 {
334 if (!can_assume(VALID_INPUT) && bufsize < 0)
335 return -FDT_ERR_NOSPACE;
336
337 FDT_RO_PROBE(fdt);
338
339 if (fdt_totalsize(fdt) > (unsigned int)bufsize)
340 return -FDT_ERR_NOSPACE;
341
342 memmove(buf, fdt, fdt_totalsize(fdt));
343 return 0;
344 }
345