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 #include <lib.h>
11 #include <dragonstub/dragonstub.h>
12 #include "libfdt_internal.h"
13
14 /*
15 * Minimal sanity check for a read-only tree. fdt_ro_probe_() checks
16 * that the given buffer contains what appears to be a flattened
17 * device tree with sane information in its header.
18 */
fdt_ro_probe_(const void * fdt)19 int32_t fdt_ro_probe_(const void *fdt)
20 {
21 uint32_t totalsize = fdt_totalsize(fdt);
22
23 if (can_assume(VALID_DTB))
24 return totalsize;
25
26 /* The device tree must be at an 8-byte aligned address */
27 if ((uintptr_t)fdt & 7)
28 return -FDT_ERR_ALIGNMENT;
29
30 if (fdt_magic(fdt) == FDT_MAGIC) {
31 /* Complete tree */
32 if (!can_assume(LATEST)) {
33 if (fdt_version(fdt) < FDT_FIRST_SUPPORTED_VERSION)
34 return -FDT_ERR_BADVERSION;
35 if (fdt_last_comp_version(fdt) >
36 FDT_LAST_SUPPORTED_VERSION)
37 return -FDT_ERR_BADVERSION;
38 }
39 } else if (fdt_magic(fdt) == FDT_SW_MAGIC) {
40 /* Unfinished sequential-write blob */
41 if (!can_assume(VALID_INPUT) && fdt_size_dt_struct(fdt) == 0)
42 return -FDT_ERR_BADSTATE;
43 } else {
44 return -FDT_ERR_BADMAGIC;
45 }
46
47 if (totalsize < INT32_MAX)
48 return totalsize;
49 else
50 return -FDT_ERR_TRUNCATED;
51 }
52
check_off_(uint32_t hdrsize,uint32_t totalsize,uint32_t off)53 static int check_off_(uint32_t hdrsize, uint32_t totalsize, uint32_t off)
54 {
55 return (off >= hdrsize) && (off <= totalsize);
56 }
57
check_block_(uint32_t hdrsize,uint32_t totalsize,uint32_t base,uint32_t size)58 static int check_block_(uint32_t hdrsize, uint32_t totalsize,
59 uint32_t base, uint32_t size)
60 {
61 if (!check_off_(hdrsize, totalsize, base))
62 return 0; /* block start out of bounds */
63 if ((base + size) < base)
64 return 0; /* overflow */
65 if (!check_off_(hdrsize, totalsize, base + size))
66 return 0; /* block end out of bounds */
67 return 1;
68 }
69
fdt_header_size_(uint32_t version)70 size_t fdt_header_size_(uint32_t version)
71 {
72 if (version <= 1)
73 return FDT_V1_SIZE;
74 else if (version <= 2)
75 return FDT_V2_SIZE;
76 else if (version <= 3)
77 return FDT_V3_SIZE;
78 else if (version <= 16)
79 return FDT_V16_SIZE;
80 else
81 return FDT_V17_SIZE;
82 }
83
fdt_header_size(const void * fdt)84 size_t fdt_header_size(const void *fdt)
85 {
86 return can_assume(LATEST) ? FDT_V17_SIZE :
87 fdt_header_size_(fdt_version(fdt));
88 }
89
fdt_check_header(const void * fdt)90 int fdt_check_header(const void *fdt)
91 {
92 size_t hdrsize;
93
94 /* The device tree must be at an 8-byte aligned address */
95 if ((uintptr_t)fdt & 7)
96 return -FDT_ERR_ALIGNMENT;
97
98 if (fdt_magic(fdt) != FDT_MAGIC)
99 return -FDT_ERR_BADMAGIC;
100 if (!can_assume(LATEST)) {
101 if ((fdt_version(fdt) < FDT_FIRST_SUPPORTED_VERSION)
102 || (fdt_last_comp_version(fdt) >
103 FDT_LAST_SUPPORTED_VERSION))
104 return -FDT_ERR_BADVERSION;
105 if (fdt_version(fdt) < fdt_last_comp_version(fdt))
106 return -FDT_ERR_BADVERSION;
107 }
108 hdrsize = fdt_header_size(fdt);
109 if (!can_assume(VALID_DTB)) {
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 /* Bounds check structure block */
120 if (!can_assume(LATEST) && fdt_version(fdt) < 17) {
121 if (!check_off_(hdrsize, fdt_totalsize(fdt),
122 fdt_off_dt_struct(fdt)))
123 return -FDT_ERR_TRUNCATED;
124 } else {
125 if (!check_block_(hdrsize, fdt_totalsize(fdt),
126 fdt_off_dt_struct(fdt),
127 fdt_size_dt_struct(fdt)))
128 return -FDT_ERR_TRUNCATED;
129 }
130
131 /* Bounds check strings block */
132 if (!check_block_(hdrsize, fdt_totalsize(fdt),
133 fdt_off_dt_strings(fdt),
134 fdt_size_dt_strings(fdt)))
135 return -FDT_ERR_TRUNCATED;
136 }
137
138 return 0;
139 }
140
fdt_offset_ptr(const void * fdt,int offset,unsigned int len)141 const void *fdt_offset_ptr(const void *fdt, int offset, unsigned int len)
142 {
143 unsigned int uoffset = offset;
144 unsigned int absoffset = offset + fdt_off_dt_struct(fdt);
145
146 if (offset < 0)
147 return NULL;
148
149 if (!can_assume(VALID_INPUT))
150 if ((absoffset < uoffset)
151 || ((absoffset + len) < absoffset)
152 || (absoffset + len) > fdt_totalsize(fdt))
153 return NULL;
154
155 if (can_assume(LATEST) || fdt_version(fdt) >= 0x11)
156 if (((uoffset + len) < uoffset)
157 || ((offset + len) > fdt_size_dt_struct(fdt)))
158 return NULL;
159
160 return fdt_offset_ptr_(fdt, offset);
161 }
162
fdt_next_tag(const void * fdt,int startoffset,int * nextoffset)163 uint32_t fdt_next_tag(const void *fdt, int startoffset, int *nextoffset)
164 {
165 const fdt32_t *tagp, *lenp;
166 uint32_t tag, len, sum;
167 int offset = startoffset;
168 const char *p;
169
170 *nextoffset = -FDT_ERR_TRUNCATED;
171 tagp = fdt_offset_ptr(fdt, offset, FDT_TAGSIZE);
172 if (!can_assume(VALID_DTB) && !tagp)
173 return FDT_END; /* premature end */
174 tag = fdt32_to_cpu(*tagp);
175 offset += FDT_TAGSIZE;
176
177 *nextoffset = -FDT_ERR_BADSTRUCTURE;
178 switch (tag) {
179 case FDT_BEGIN_NODE:
180 /* skip name */
181 do {
182 p = fdt_offset_ptr(fdt, offset++, 1);
183 } while (p && (*p != '\0'));
184 if (!can_assume(VALID_DTB) && !p)
185 return FDT_END; /* premature end */
186 break;
187
188 case FDT_PROP:
189 lenp = fdt_offset_ptr(fdt, offset, sizeof(*lenp));
190 if (!can_assume(VALID_DTB) && !lenp)
191 return FDT_END; /* premature end */
192
193 len = fdt32_to_cpu(*lenp);
194 sum = len + offset;
195 if (!can_assume(VALID_DTB) &&
196 (INT_MAX <= sum || sum < (uint32_t) offset))
197 return FDT_END; /* premature end */
198
199 /* skip-name offset, length and value */
200 offset += sizeof(struct fdt_property) - FDT_TAGSIZE + len;
201
202 if (!can_assume(LATEST) &&
203 fdt_version(fdt) < 0x10 && len >= 8 &&
204 ((offset - len) % 8) != 0)
205 offset += 4;
206 break;
207
208 case FDT_END:
209 case FDT_END_NODE:
210 case FDT_NOP:
211 break;
212
213 default:
214 return FDT_END;
215 }
216
217 if (!fdt_offset_ptr(fdt, startoffset, offset - startoffset))
218 return FDT_END; /* premature end */
219
220 *nextoffset = FDT_TAGALIGN(offset);
221 return tag;
222 }
223
fdt_check_node_offset_(const void * fdt,int offset)224 int fdt_check_node_offset_(const void *fdt, int offset)
225 {
226 if (!can_assume(VALID_INPUT)
227 && ((offset < 0) || (offset % FDT_TAGSIZE)))
228 return -FDT_ERR_BADOFFSET;
229
230 if (fdt_next_tag(fdt, offset, &offset) != FDT_BEGIN_NODE)
231 return -FDT_ERR_BADOFFSET;
232
233 return offset;
234 }
235
fdt_check_prop_offset_(const void * fdt,int offset)236 int fdt_check_prop_offset_(const void *fdt, int offset)
237 {
238 if (!can_assume(VALID_INPUT)
239 && ((offset < 0) || (offset % FDT_TAGSIZE)))
240 return -FDT_ERR_BADOFFSET;
241
242 if (fdt_next_tag(fdt, offset, &offset) != FDT_PROP)
243 return -FDT_ERR_BADOFFSET;
244
245 return offset;
246 }
247
fdt_next_node(const void * fdt,int offset,int * depth)248 int fdt_next_node(const void *fdt, int offset, int *depth)
249 {
250 int nextoffset = 0;
251 uint32_t tag;
252
253 if (offset >= 0)
254 if ((nextoffset = fdt_check_node_offset_(fdt, offset)) < 0)
255 return nextoffset;
256
257 do {
258 offset = nextoffset;
259 tag = fdt_next_tag(fdt, offset, &nextoffset);
260
261 switch (tag) {
262 case FDT_PROP:
263 case FDT_NOP:
264 break;
265
266 case FDT_BEGIN_NODE:
267 if (depth)
268 (*depth)++;
269 break;
270
271 case FDT_END_NODE:
272 if (depth && ((--(*depth)) < 0))
273 return nextoffset;
274 break;
275
276 case FDT_END:
277 if ((nextoffset >= 0)
278 || ((nextoffset == -FDT_ERR_TRUNCATED) && !depth))
279 return -FDT_ERR_NOTFOUND;
280 else
281 return nextoffset;
282 }
283 } while (tag != FDT_BEGIN_NODE);
284
285 return offset;
286 }
287
fdt_first_subnode(const void * fdt,int offset)288 int fdt_first_subnode(const void *fdt, int offset)
289 {
290 int depth = 0;
291
292 offset = fdt_next_node(fdt, offset, &depth);
293 if (offset < 0 || depth != 1)
294 return -FDT_ERR_NOTFOUND;
295
296 return offset;
297 }
298
fdt_next_subnode(const void * fdt,int offset)299 int fdt_next_subnode(const void *fdt, int offset)
300 {
301 int depth = 1;
302
303 /*
304 * With respect to the parent, the depth of the next subnode will be
305 * the same as the last.
306 */
307 do {
308 offset = fdt_next_node(fdt, offset, &depth);
309 if (offset < 0 || depth < 1)
310 return -FDT_ERR_NOTFOUND;
311 } while (depth > 1);
312
313 return offset;
314 }
315
fdt_find_string_(const char * strtab,int tabsize,const char * s)316 const char *fdt_find_string_(const char *strtab, int tabsize, const char *s)
317 {
318 int len = strlen(s) + 1;
319 const char *last = strtab + tabsize - len;
320 const char *p;
321
322 for (p = strtab; p <= last; p++)
323 if (memcmp(p, s, len) == 0)
324 return p;
325 return NULL;
326 }
327
fdt_move(const void * fdt,void * buf,int bufsize)328 int fdt_move(const void *fdt, void *buf, int bufsize)
329 {
330 if (!can_assume(VALID_INPUT) && bufsize < 0)
331 return -FDT_ERR_NOSPACE;
332
333 FDT_RO_PROBE(fdt);
334
335 if (fdt_totalsize(fdt) > (unsigned int)bufsize)
336 return -FDT_ERR_NOSPACE;
337
338 memmove(buf, fdt, fdt_totalsize(fdt));
339 return 0;
340 }
341