fdt.c 7.6 KB

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