scripts/dtc/libfdt/fdt.c

   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  */
  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         if (fdt_magic(fdt) == FDT_MAGIC) {
  26                 /* Complete tree */
  27                 if (!can_assume(LATEST)) {
  28                         if (fdt_version(fdt) < FDT_FIRST_SUPPORTED_VERSION)
  29                                 return -FDT_ERR_BADVERSION;
  30                         if (fdt_last_comp_version(fdt) >
  31                                         FDT_LAST_SUPPORTED_VERSION)
  32                                 return -FDT_ERR_BADVERSION;
  33                 }
  34         } else if (fdt_magic(fdt) == FDT_SW_MAGIC) {
  35                 /* Unfinished sequential-write blob */
  36                 if (!can_assume(VALID_INPUT) && fdt_size_dt_struct(fdt) == 0)
  37                         return -FDT_ERR_BADSTATE;
  38         } else {
  39                 return -FDT_ERR_BADMAGIC;
  40         }
  41
  42         if (totalsize < INT32_MAX)
  43                 return totalsize;
  44         else
  45                 return -FDT_ERR_TRUNCATED;
  46 }
  47
  48 static int check_off_(uint32_t hdrsize, uint32_t totalsize, uint32_t off)
  49 {
  50         return (off >= hdrsize) && (off <= totalsize);
  51 }
  52
  53 static int check_block_(uint32_t hdrsize, uint32_t totalsize,
  54                         uint32_t base, uint32_t size)
  55 {
  56         if (!check_off_(hdrsize, totalsize, base))
  57                 return 0; /* block start out of bounds */
  58         if ((base + size) < base)
  59                 return 0; /* overflow */
  60         if (!check_off_(hdrsize, totalsize, base + size))
  61                 return 0; /* block end out of bounds */
  62         return 1;
  63 }
  64
  65 size_t fdt_header_size_(uint32_t version)
  66 {
  67         if (version <= 1)
  68                 return FDT_V1_SIZE;
  69         else if (version <= 2)
  70                 return FDT_V2_SIZE;
  71         else if (version <= 3)
  72                 return FDT_V3_SIZE;
  73         else if (version <= 16)
  74                 return FDT_V16_SIZE;
  75         else
  76                 return FDT_V17_SIZE;
  77 }
  78
  79 size_t fdt_header_size(const void *fdt)
  80 {
  81         return can_assume(LATEST) ? FDT_V17_SIZE :
  82                 fdt_header_size_(fdt_version(fdt));
  83 }
  84
  85 int fdt_check_header(const void *fdt)
  86 {
  87         size_t hdrsize;
  88
  89         if (fdt_magic(fdt) != FDT_MAGIC)
  90                 return -FDT_ERR_BADMAGIC;
  91         if (!can_assume(LATEST)) {
  92                 if ((fdt_version(fdt) < FDT_FIRST_SUPPORTED_VERSION)
  93                     || (fdt_last_comp_version(fdt) >
  94                         FDT_LAST_SUPPORTED_VERSION))
  95                         return -FDT_ERR_BADVERSION;
  96                 if (fdt_version(fdt) < fdt_last_comp_version(fdt))
  97                         return -FDT_ERR_BADVERSION;
  98         }
  99         hdrsize = fdt_header_size(fdt);
 100         if (!can_assume(VALID_DTB)) {
 101
 102                 if ((fdt_totalsize(fdt) < hdrsize)
 103                     || (fdt_totalsize(fdt) > INT_MAX))
 104                         return -FDT_ERR_TRUNCATED;
 105
 106                 /* Bounds check memrsv block */
 107                 if (!check_off_(hdrsize, fdt_totalsize(fdt),
 108                                 fdt_off_mem_rsvmap(fdt)))
 109                         return -FDT_ERR_TRUNCATED;
 110         }
 111
 112         if (!can_assume(VALID_DTB)) {
 113                 /* Bounds check structure block */
 114                 if (!can_assume(LATEST) && fdt_version(fdt) < 17) {
 115                         if (!check_off_(hdrsize, fdt_totalsize(fdt),
 116                                         fdt_off_dt_struct(fdt)))
 117                                 return -FDT_ERR_TRUNCATED;
 118                 } else {
 119                         if (!check_block_(hdrsize, fdt_totalsize(fdt),
 120                                           fdt_off_dt_struct(fdt),
 121                                           fdt_size_dt_struct(fdt)))
 122                                 return -FDT_ERR_TRUNCATED;
 123                 }
 124
 125                 /* Bounds check strings block */
 126                 if (!check_block_(hdrsize, fdt_totalsize(fdt),
 127                                   fdt_off_dt_strings(fdt),
 128                                   fdt_size_dt_strings(fdt)))
 129                         return -FDT_ERR_TRUNCATED;
 130         }
 131
 132         return 0;
 133 }
 134
 135 const void *fdt_offset_ptr(const void *fdt, int offset, unsigned int len)
 136 {
 137         unsigned int uoffset = offset;
 138         unsigned int absoffset = offset + fdt_off_dt_struct(fdt);
 139
 140         if (offset < 0)
 141                 return NULL;
 142
 143         if (!can_assume(VALID_INPUT))
 144                 if ((absoffset < uoffset)
 145                     || ((absoffset + len) < absoffset)
 146                     || (absoffset + len) > fdt_totalsize(fdt))
 147                         return NULL;
 148
 149         if (can_assume(LATEST) || fdt_version(fdt) >= 0x11)
 150                 if (((uoffset + len) < uoffset)
 151                     || ((offset + len) > fdt_size_dt_struct(fdt)))
 152                         return NULL;
 153
 154         return fdt_offset_ptr_(fdt, offset);
 155 }
 156
 157 uint32_t fdt_next_tag(const void *fdt, int startoffset, int *nextoffset)
 158 {
 159         const fdt32_t *tagp, *lenp;
 160         uint32_t tag;
 161         int offset = startoffset;
 162         const char *p;
 163
 164         *nextoffset = -FDT_ERR_TRUNCATED;
 165         tagp = fdt_offset_ptr(fdt, offset, FDT_TAGSIZE);
 166         if (!can_assume(VALID_DTB) && !tagp)
 167                 return FDT_END; /* premature end */
 168         tag = fdt32_to_cpu(*tagp);
 169         offset += FDT_TAGSIZE;
 170
 171         *nextoffset = -FDT_ERR_BADSTRUCTURE;
 172         switch (tag) {
 173         case FDT_BEGIN_NODE:
 174                 /* skip name */
 175                 do {
 176                         p = fdt_offset_ptr(fdt, offset++, 1);
 177                 } while (p && (*p != '\0'));
 178                 if (!can_assume(VALID_DTB) && !p)
 179                         return FDT_END; /* premature end */
 180                 break;
 181
 182         case FDT_PROP:
 183                 lenp = fdt_offset_ptr(fdt, offset, sizeof(*lenp));
 184                 if (!can_assume(VALID_DTB) && !lenp)
 185                         return FDT_END; /* premature end */
 186                 /* skip-name offset, length and value */
 187                 offset += sizeof(struct fdt_property) - FDT_TAGSIZE
 188                         + fdt32_to_cpu(*lenp);
 189                 if (!can_assume(LATEST) &&
 190                     fdt_version(fdt) < 0x10 && fdt32_to_cpu(*lenp) >= 8 &&
 191                     ((offset - fdt32_to_cpu(*lenp)) % 8) != 0)
 192                         offset += 4;
 193                 break;
 194
 195         case FDT_END:
 196         case FDT_END_NODE:
 197         case FDT_NOP:
 198                 break;
 199
 200         default:
 201                 return FDT_END;
 202         }
 203
 204         if (!fdt_offset_ptr(fdt, startoffset, offset - startoffset))
 205                 return FDT_END; /* premature end */
 206
 207         *nextoffset = FDT_TAGALIGN(offset);
 208         return tag;
 209 }
 210
 211 int fdt_check_node_offset_(const void *fdt, int offset)
 212 {
 213         if (!can_assume(VALID_INPUT)
 214             && ((offset < 0) || (offset % FDT_TAGSIZE)))
 215                 return -FDT_ERR_BADOFFSET;
 216
 217         if (fdt_next_tag(fdt, offset, &offset) != FDT_BEGIN_NODE)
 218                 return -FDT_ERR_BADOFFSET;
 219
 220         return offset;
 221 }
 222
 223 int fdt_check_prop_offset_(const void *fdt, int offset)
 224 {
 225         if (!can_assume(VALID_INPUT)
 226             && ((offset < 0) || (offset % FDT_TAGSIZE)))
 227                 return -FDT_ERR_BADOFFSET;
 228
 229         if (fdt_next_tag(fdt, offset, &offset) != FDT_PROP)
 230                 return -FDT_ERR_BADOFFSET;
 231
 232         return offset;
 233 }
 234
 235 int fdt_next_node(const void *fdt, int offset, int *depth)
 236 {
 237         int nextoffset = 0;
 238         uint32_t tag;
 239
 240         if (offset >= 0)
 241                 if ((nextoffset = fdt_check_node_offset_(fdt, offset)) < 0)
 242                         return nextoffset;
 243
 244         do {
 245                 offset = nextoffset;
 246                 tag = fdt_next_tag(fdt, offset, &nextoffset);
 247
 248                 switch (tag) {
 249                 case FDT_PROP:
 250                 case FDT_NOP:
 251                         break;
 252
 253                 case FDT_BEGIN_NODE:
 254                         if (depth)
 255                                 (*depth)++;
 256                         break;
 257
 258                 case FDT_END_NODE:
 259                         if (depth && ((--(*depth)) < 0))
 260                                 return nextoffset;
 261                         break;
 262
 263                 case FDT_END:
 264                         if ((nextoffset >= 0)
 265                             || ((nextoffset == -FDT_ERR_TRUNCATED) && !depth))
 266                                 return -FDT_ERR_NOTFOUND;
 267                         else
 268                                 return nextoffset;
 269                 }
 270         } while (tag != FDT_BEGIN_NODE);
 271
 272         return offset;
 273 }
 274
 275 int fdt_first_subnode(const void *fdt, int offset)
 276 {
 277         int depth = 0;
 278
 279         offset = fdt_next_node(fdt, offset, &depth);
 280         if (offset < 0 || depth != 1)
 281                 return -FDT_ERR_NOTFOUND;
 282
 283         return offset;
 284 }
 285
 286 int fdt_next_subnode(const void *fdt, int offset)
 287 {
 288         int depth = 1;
 289
 290         /*
 291          * With respect to the parent, the depth of the next subnode will be
 292          * the same as the last.
 293          */
 294         do {
 295                 offset = fdt_next_node(fdt, offset, &depth);
 296                 if (offset < 0 || depth < 1)
 297                         return -FDT_ERR_NOTFOUND;
 298         } while (depth > 1);
 299
 300         return offset;
 301 }
 302
 303 const char *fdt_find_string_(const char *strtab, int tabsize, const char *s)
 304 {
 305         int len = strlen(s) + 1;
 306         const char *last = strtab + tabsize - len;
 307         const char *p;
 308
 309         for (p = strtab; p <= last; p++)
 310                 if (memcmp(p, s, len) == 0)
 311                         return p;
 312         return NULL;
 313 }
 314
 315 int fdt_move(const void *fdt, void *buf, int bufsize)
 316 {
 317         if (!can_assume(VALID_INPUT) && bufsize < 0)
 318                 return -FDT_ERR_NOSPACE;
 319
 320         FDT_RO_PROBE(fdt);
 321
 322         if (fdt_totalsize(fdt) > (unsigned int)bufsize)
 323                 return -FDT_ERR_NOSPACE;
 324
 325         memmove(buf, fdt, fdt_totalsize(fdt));
 326         return 0;
 327 }