xref: /openbmc/linux/scripts/dtc/libfdt/fdt.c (revision b7019ac5)
1 /*
2  * libfdt - Flat Device Tree manipulation
3  * Copyright (C) 2006 David Gibson, IBM Corporation.
4  *
5  * libfdt is dual licensed: you can use it either under the terms of
6  * the GPL, or the BSD license, at your option.
7  *
8  *  a) This library is free software; you can redistribute it and/or
9  *     modify it under the terms of the GNU General Public License as
10  *     published by the Free Software Foundation; either version 2 of the
11  *     License, or (at your option) any later version.
12  *
13  *     This library is distributed in the hope that it will be useful,
14  *     but WITHOUT ANY WARRANTY; without even the implied warranty of
15  *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16  *     GNU General Public License for more details.
17  *
18  *     You should have received a copy of the GNU General Public
19  *     License along with this library; if not, write to the Free
20  *     Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
21  *     MA 02110-1301 USA
22  *
23  * Alternatively,
24  *
25  *  b) Redistribution and use in source and binary forms, with or
26  *     without modification, are permitted provided that the following
27  *     conditions are met:
28  *
29  *     1. Redistributions of source code must retain the above
30  *        copyright notice, this list of conditions and the following
31  *        disclaimer.
32  *     2. Redistributions in binary form must reproduce the above
33  *        copyright notice, this list of conditions and the following
34  *        disclaimer in the documentation and/or other materials
35  *        provided with the distribution.
36  *
37  *     THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
38  *     CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
39  *     INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
40  *     MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
41  *     DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
42  *     CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
43  *     SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
44  *     NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
45  *     LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
46  *     HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
47  *     CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
48  *     OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
49  *     EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
50  */
51 #include "libfdt_env.h"
52 
53 #include <fdt.h>
54 #include <libfdt.h>
55 
56 #include "libfdt_internal.h"
57 
58 /*
59  * Minimal sanity check for a read-only tree. fdt_ro_probe_() checks
60  * that the given buffer contains what appears to be a flattened
61  * device tree with sane information in its header.
62  */
63 int fdt_ro_probe_(const void *fdt)
64 {
65 	if (fdt_magic(fdt) == FDT_MAGIC) {
66 		/* Complete tree */
67 		if (fdt_version(fdt) < FDT_FIRST_SUPPORTED_VERSION)
68 			return -FDT_ERR_BADVERSION;
69 		if (fdt_last_comp_version(fdt) > FDT_LAST_SUPPORTED_VERSION)
70 			return -FDT_ERR_BADVERSION;
71 	} else if (fdt_magic(fdt) == FDT_SW_MAGIC) {
72 		/* Unfinished sequential-write blob */
73 		if (fdt_size_dt_struct(fdt) == 0)
74 			return -FDT_ERR_BADSTATE;
75 	} else {
76 		return -FDT_ERR_BADMAGIC;
77 	}
78 
79 	return 0;
80 }
81 
82 static int check_off_(uint32_t hdrsize, uint32_t totalsize, uint32_t off)
83 {
84 	return (off >= hdrsize) && (off <= totalsize);
85 }
86 
87 static int check_block_(uint32_t hdrsize, uint32_t totalsize,
88 			uint32_t base, uint32_t size)
89 {
90 	if (!check_off_(hdrsize, totalsize, base))
91 		return 0; /* block start out of bounds */
92 	if ((base + size) < base)
93 		return 0; /* overflow */
94 	if (!check_off_(hdrsize, totalsize, base + size))
95 		return 0; /* block end out of bounds */
96 	return 1;
97 }
98 
99 size_t fdt_header_size_(uint32_t version)
100 {
101 	if (version <= 1)
102 		return FDT_V1_SIZE;
103 	else if (version <= 2)
104 		return FDT_V2_SIZE;
105 	else if (version <= 3)
106 		return FDT_V3_SIZE;
107 	else if (version <= 16)
108 		return FDT_V16_SIZE;
109 	else
110 		return FDT_V17_SIZE;
111 }
112 
113 int fdt_check_header(const void *fdt)
114 {
115 	size_t hdrsize;
116 
117 	if (fdt_magic(fdt) != FDT_MAGIC)
118 		return -FDT_ERR_BADMAGIC;
119 	hdrsize = fdt_header_size(fdt);
120 	if ((fdt_version(fdt) < FDT_FIRST_SUPPORTED_VERSION)
121 	    || (fdt_last_comp_version(fdt) > FDT_LAST_SUPPORTED_VERSION))
122 		return -FDT_ERR_BADVERSION;
123 	if (fdt_version(fdt) < fdt_last_comp_version(fdt))
124 		return -FDT_ERR_BADVERSION;
125 
126 	if ((fdt_totalsize(fdt) < hdrsize)
127 	    || (fdt_totalsize(fdt) > INT_MAX))
128 		return -FDT_ERR_TRUNCATED;
129 
130 	/* Bounds check memrsv block */
131 	if (!check_off_(hdrsize, fdt_totalsize(fdt), fdt_off_mem_rsvmap(fdt)))
132 		return -FDT_ERR_TRUNCATED;
133 
134 	/* Bounds check structure block */
135 	if (fdt_version(fdt) < 17) {
136 		if (!check_off_(hdrsize, fdt_totalsize(fdt),
137 				fdt_off_dt_struct(fdt)))
138 			return -FDT_ERR_TRUNCATED;
139 	} else {
140 		if (!check_block_(hdrsize, fdt_totalsize(fdt),
141 				  fdt_off_dt_struct(fdt),
142 				  fdt_size_dt_struct(fdt)))
143 			return -FDT_ERR_TRUNCATED;
144 	}
145 
146 	/* Bounds check strings block */
147 	if (!check_block_(hdrsize, fdt_totalsize(fdt),
148 			  fdt_off_dt_strings(fdt), fdt_size_dt_strings(fdt)))
149 		return -FDT_ERR_TRUNCATED;
150 
151 	return 0;
152 }
153 
154 const void *fdt_offset_ptr(const void *fdt, int offset, unsigned int len)
155 {
156 	unsigned absoffset = offset + fdt_off_dt_struct(fdt);
157 
158 	if ((absoffset < offset)
159 	    || ((absoffset + len) < absoffset)
160 	    || (absoffset + len) > fdt_totalsize(fdt))
161 		return NULL;
162 
163 	if (fdt_version(fdt) >= 0x11)
164 		if (((offset + len) < offset)
165 		    || ((offset + len) > fdt_size_dt_struct(fdt)))
166 			return NULL;
167 
168 	return fdt_offset_ptr_(fdt, offset);
169 }
170 
171 uint32_t fdt_next_tag(const void *fdt, int startoffset, int *nextoffset)
172 {
173 	const fdt32_t *tagp, *lenp;
174 	uint32_t tag;
175 	int offset = startoffset;
176 	const char *p;
177 
178 	*nextoffset = -FDT_ERR_TRUNCATED;
179 	tagp = fdt_offset_ptr(fdt, offset, FDT_TAGSIZE);
180 	if (!tagp)
181 		return FDT_END; /* premature end */
182 	tag = fdt32_to_cpu(*tagp);
183 	offset += FDT_TAGSIZE;
184 
185 	*nextoffset = -FDT_ERR_BADSTRUCTURE;
186 	switch (tag) {
187 	case FDT_BEGIN_NODE:
188 		/* skip name */
189 		do {
190 			p = fdt_offset_ptr(fdt, offset++, 1);
191 		} while (p && (*p != '\0'));
192 		if (!p)
193 			return FDT_END; /* premature end */
194 		break;
195 
196 	case FDT_PROP:
197 		lenp = fdt_offset_ptr(fdt, offset, sizeof(*lenp));
198 		if (!lenp)
199 			return FDT_END; /* premature end */
200 		/* skip-name offset, length and value */
201 		offset += sizeof(struct fdt_property) - FDT_TAGSIZE
202 			+ fdt32_to_cpu(*lenp);
203 		if (fdt_version(fdt) < 0x10 && fdt32_to_cpu(*lenp) >= 8 &&
204 		    ((offset - fdt32_to_cpu(*lenp)) % 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 
224 int fdt_check_node_offset_(const void *fdt, int offset)
225 {
226 	if ((offset < 0) || (offset % FDT_TAGSIZE)
227 	    || (fdt_next_tag(fdt, offset, &offset) != FDT_BEGIN_NODE))
228 		return -FDT_ERR_BADOFFSET;
229 
230 	return offset;
231 }
232 
233 int fdt_check_prop_offset_(const void *fdt, int offset)
234 {
235 	if ((offset < 0) || (offset % FDT_TAGSIZE)
236 	    || (fdt_next_tag(fdt, offset, &offset) != FDT_PROP))
237 		return -FDT_ERR_BADOFFSET;
238 
239 	return offset;
240 }
241 
242 int fdt_next_node(const void *fdt, int offset, int *depth)
243 {
244 	int nextoffset = 0;
245 	uint32_t tag;
246 
247 	if (offset >= 0)
248 		if ((nextoffset = fdt_check_node_offset_(fdt, offset)) < 0)
249 			return nextoffset;
250 
251 	do {
252 		offset = nextoffset;
253 		tag = fdt_next_tag(fdt, offset, &nextoffset);
254 
255 		switch (tag) {
256 		case FDT_PROP:
257 		case FDT_NOP:
258 			break;
259 
260 		case FDT_BEGIN_NODE:
261 			if (depth)
262 				(*depth)++;
263 			break;
264 
265 		case FDT_END_NODE:
266 			if (depth && ((--(*depth)) < 0))
267 				return nextoffset;
268 			break;
269 
270 		case FDT_END:
271 			if ((nextoffset >= 0)
272 			    || ((nextoffset == -FDT_ERR_TRUNCATED) && !depth))
273 				return -FDT_ERR_NOTFOUND;
274 			else
275 				return nextoffset;
276 		}
277 	} while (tag != FDT_BEGIN_NODE);
278 
279 	return offset;
280 }
281 
282 int fdt_first_subnode(const void *fdt, int offset)
283 {
284 	int depth = 0;
285 
286 	offset = fdt_next_node(fdt, offset, &depth);
287 	if (offset < 0 || depth != 1)
288 		return -FDT_ERR_NOTFOUND;
289 
290 	return offset;
291 }
292 
293 int fdt_next_subnode(const void *fdt, int offset)
294 {
295 	int depth = 1;
296 
297 	/*
298 	 * With respect to the parent, the depth of the next subnode will be
299 	 * the same as the last.
300 	 */
301 	do {
302 		offset = fdt_next_node(fdt, offset, &depth);
303 		if (offset < 0 || depth < 1)
304 			return -FDT_ERR_NOTFOUND;
305 	} while (depth > 1);
306 
307 	return offset;
308 }
309 
310 const char *fdt_find_string_(const char *strtab, int tabsize, const char *s)
311 {
312 	int len = strlen(s) + 1;
313 	const char *last = strtab + tabsize - len;
314 	const char *p;
315 
316 	for (p = strtab; p <= last; p++)
317 		if (memcmp(p, s, len) == 0)
318 			return p;
319 	return NULL;
320 }
321 
322 int fdt_move(const void *fdt, void *buf, int bufsize)
323 {
324 	FDT_RO_PROBE(fdt);
325 
326 	if (fdt_totalsize(fdt) > bufsize)
327 		return -FDT_ERR_NOSPACE;
328 
329 	memmove(buf, fdt, fdt_totalsize(fdt));
330 	return 0;
331 }
332