fdt.c 7.1 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 (fdt_magic(fdt) == FDT_MAGIC) {
  19. /* Complete tree */
  20. if (fdt_chk_version()) {
  21. if (fdt_version(fdt) < FDT_FIRST_SUPPORTED_VERSION)
  22. return -FDT_ERR_BADVERSION;
  23. if (fdt_last_comp_version(fdt) >
  24. FDT_LAST_SUPPORTED_VERSION)
  25. return -FDT_ERR_BADVERSION;
  26. }
  27. } else if (fdt_magic(fdt) == FDT_SW_MAGIC) {
  28. /* Unfinished sequential-write blob */
  29. if (fdt_size_dt_struct(fdt) == 0)
  30. return -FDT_ERR_BADSTATE;
  31. } else {
  32. return -FDT_ERR_BADMAGIC;
  33. }
  34. if (totalsize < INT32_MAX)
  35. return totalsize;
  36. else
  37. return -FDT_ERR_TRUNCATED;
  38. }
  39. static int check_off_(uint32_t hdrsize, uint32_t totalsize, uint32_t off)
  40. {
  41. return (off >= hdrsize) && (off <= totalsize);
  42. }
  43. static int check_block_(uint32_t hdrsize, uint32_t totalsize,
  44. uint32_t base, uint32_t size)
  45. {
  46. if (!check_off_(hdrsize, totalsize, base))
  47. return 0; /* block start out of bounds */
  48. if ((base + size) < base)
  49. return 0; /* overflow */
  50. if (!check_off_(hdrsize, totalsize, base + size))
  51. return 0; /* block end out of bounds */
  52. return 1;
  53. }
  54. size_t fdt_header_size_(uint32_t version)
  55. {
  56. if (version <= 1)
  57. return FDT_V1_SIZE;
  58. else if (version <= 2)
  59. return FDT_V2_SIZE;
  60. else if (version <= 3)
  61. return FDT_V3_SIZE;
  62. else if (version <= 16)
  63. return FDT_V16_SIZE;
  64. else
  65. return FDT_V17_SIZE;
  66. }
  67. size_t fdt_header_size(const void *fdt)
  68. {
  69. return fdt_chk_version() ? fdt_header_size_(fdt_version(fdt)) :
  70. FDT_V17_SIZE;
  71. }
  72. int fdt_check_header(const void *fdt)
  73. {
  74. size_t hdrsize;
  75. if (fdt_magic(fdt) != FDT_MAGIC)
  76. return -FDT_ERR_BADMAGIC;
  77. if (fdt_chk_version()) {
  78. if ((fdt_version(fdt) < FDT_FIRST_SUPPORTED_VERSION)
  79. || (fdt_last_comp_version(fdt) >
  80. FDT_LAST_SUPPORTED_VERSION))
  81. return -FDT_ERR_BADVERSION;
  82. if (fdt_version(fdt) < fdt_last_comp_version(fdt))
  83. return -FDT_ERR_BADVERSION;
  84. }
  85. hdrsize = fdt_header_size(fdt);
  86. if (fdt_chk_basic()) {
  87. if ((fdt_totalsize(fdt) < hdrsize)
  88. || (fdt_totalsize(fdt) > INT_MAX))
  89. return -FDT_ERR_TRUNCATED;
  90. /* Bounds check memrsv block */
  91. if (!check_off_(hdrsize, fdt_totalsize(fdt),
  92. fdt_off_mem_rsvmap(fdt)))
  93. return -FDT_ERR_TRUNCATED;
  94. }
  95. if (fdt_chk_extra()) {
  96. /* Bounds check structure block */
  97. if (fdt_chk_version() && fdt_version(fdt) < 17) {
  98. if (!check_off_(hdrsize, fdt_totalsize(fdt),
  99. fdt_off_dt_struct(fdt)))
  100. return -FDT_ERR_TRUNCATED;
  101. } else {
  102. if (!check_block_(hdrsize, fdt_totalsize(fdt),
  103. fdt_off_dt_struct(fdt),
  104. fdt_size_dt_struct(fdt)))
  105. return -FDT_ERR_TRUNCATED;
  106. }
  107. /* Bounds check strings block */
  108. if (!check_block_(hdrsize, fdt_totalsize(fdt),
  109. fdt_off_dt_strings(fdt),
  110. fdt_size_dt_strings(fdt)))
  111. return -FDT_ERR_TRUNCATED;
  112. }
  113. return 0;
  114. }
  115. const void *fdt_offset_ptr(const void *fdt, int offset, unsigned int len)
  116. {
  117. unsigned int uoffset = offset;
  118. unsigned int absoffset = offset + fdt_off_dt_struct(fdt);
  119. if (offset < 0)
  120. return NULL;
  121. if (fdt_chk_basic())
  122. if ((absoffset < uoffset)
  123. || ((absoffset + len) < absoffset)
  124. || (absoffset + len) > fdt_totalsize(fdt))
  125. return NULL;
  126. if (!fdt_chk_version() || fdt_version(fdt) >= 0x11)
  127. if (((uoffset + len) < uoffset)
  128. || ((offset + len) > fdt_size_dt_struct(fdt)))
  129. return NULL;
  130. return fdt_offset_ptr_(fdt, offset);
  131. }
  132. uint32_t fdt_next_tag(const void *fdt, int startoffset, int *nextoffset)
  133. {
  134. const fdt32_t *tagp, *lenp;
  135. uint32_t tag;
  136. int offset = startoffset;
  137. const char *p;
  138. *nextoffset = -FDT_ERR_TRUNCATED;
  139. tagp = fdt_offset_ptr(fdt, offset, FDT_TAGSIZE);
  140. if (fdt_chk_basic() && !tagp)
  141. return FDT_END; /* premature end */
  142. tag = fdt32_to_cpu(*tagp);
  143. offset += FDT_TAGSIZE;
  144. *nextoffset = -FDT_ERR_BADSTRUCTURE;
  145. switch (tag) {
  146. case FDT_BEGIN_NODE:
  147. /* skip name */
  148. do {
  149. p = fdt_offset_ptr(fdt, offset++, 1);
  150. } while (p && (*p != '\0'));
  151. if (fdt_chk_basic() && !p)
  152. return FDT_END; /* premature end */
  153. break;
  154. case FDT_PROP:
  155. lenp = fdt_offset_ptr(fdt, offset, sizeof(*lenp));
  156. if (fdt_chk_basic() && !lenp)
  157. return FDT_END; /* premature end */
  158. /* skip-name offset, length and value */
  159. offset += sizeof(struct fdt_property) - FDT_TAGSIZE
  160. + fdt32_to_cpu(*lenp);
  161. if (fdt_chk_version() &&
  162. fdt_version(fdt) < 0x10 && fdt32_to_cpu(*lenp) >= 8 &&
  163. ((offset - fdt32_to_cpu(*lenp)) % 8) != 0)
  164. offset += 4;
  165. break;
  166. case FDT_END:
  167. case FDT_END_NODE:
  168. case FDT_NOP:
  169. break;
  170. default:
  171. return FDT_END;
  172. }
  173. if (fdt_chk_basic() &&
  174. !fdt_offset_ptr(fdt, startoffset, offset - startoffset))
  175. return FDT_END; /* premature end */
  176. *nextoffset = FDT_TAGALIGN(offset);
  177. return tag;
  178. }
  179. int fdt_check_node_offset_(const void *fdt, int offset)
  180. {
  181. if ((offset < 0) || (offset % FDT_TAGSIZE)
  182. || (fdt_next_tag(fdt, offset, &offset) != FDT_BEGIN_NODE))
  183. return -FDT_ERR_BADOFFSET;
  184. return offset;
  185. }
  186. int fdt_check_prop_offset_(const void *fdt, int offset)
  187. {
  188. if ((offset < 0) || (offset % FDT_TAGSIZE)
  189. || (fdt_next_tag(fdt, offset, &offset) != FDT_PROP))
  190. return -FDT_ERR_BADOFFSET;
  191. return offset;
  192. }
  193. int fdt_next_node(const void *fdt, int offset, int *depth)
  194. {
  195. int nextoffset = 0;
  196. uint32_t tag;
  197. if (offset >= 0)
  198. if ((nextoffset = fdt_check_node_offset_(fdt, offset)) < 0)
  199. return nextoffset;
  200. do {
  201. offset = nextoffset;
  202. tag = fdt_next_tag(fdt, offset, &nextoffset);
  203. switch (tag) {
  204. case FDT_PROP:
  205. case FDT_NOP:
  206. break;
  207. case FDT_BEGIN_NODE:
  208. if (depth)
  209. (*depth)++;
  210. break;
  211. case FDT_END_NODE:
  212. if (depth && ((--(*depth)) < 0))
  213. return nextoffset;
  214. break;
  215. case FDT_END:
  216. if ((nextoffset >= 0)
  217. || ((nextoffset == -FDT_ERR_TRUNCATED) && !depth))
  218. return -FDT_ERR_NOTFOUND;
  219. else
  220. return nextoffset;
  221. }
  222. } while (tag != FDT_BEGIN_NODE);
  223. return offset;
  224. }
  225. int fdt_first_subnode(const void *fdt, int offset)
  226. {
  227. int depth = 0;
  228. offset = fdt_next_node(fdt, offset, &depth);
  229. if (offset < 0 || depth != 1)
  230. return -FDT_ERR_NOTFOUND;
  231. return offset;
  232. }
  233. int fdt_next_subnode(const void *fdt, int offset)
  234. {
  235. int depth = 1;
  236. /*
  237. * With respect to the parent, the depth of the next subnode will be
  238. * the same as the last.
  239. */
  240. do {
  241. offset = fdt_next_node(fdt, offset, &depth);
  242. if (offset < 0 || depth < 1)
  243. return -FDT_ERR_NOTFOUND;
  244. } while (depth > 1);
  245. return offset;
  246. }
  247. const char *fdt_find_string_(const char *strtab, int tabsize, const char *s)
  248. {
  249. int len = strlen(s) + 1;
  250. const char *last = strtab + tabsize - len;
  251. const char *p;
  252. for (p = strtab; p <= last; p++)
  253. if (memcmp(p, s, len) == 0)
  254. return p;
  255. return NULL;
  256. }
  257. int fdt_move(const void *fdt, void *buf, int bufsize)
  258. {
  259. if (fdt_chk_basic() && bufsize < 0)
  260. return -FDT_ERR_NOSPACE;
  261. FDT_RO_PROBE(fdt);
  262. if (fdt_totalsize(fdt) > (unsigned int)bufsize)
  263. return -FDT_ERR_NOSPACE;
  264. memmove(buf, fdt, fdt_totalsize(fdt));
  265. return 0;
  266. }