LXR linux/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 */
  18int32_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
  48static int check_off_(uint32_t hdrsize, uint32_t totalsize, uint32_t off)
  49{
  50        return (off >= hdrsize) && (off <= totalsize);
  51}
  52
  53static 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
  65size_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
  79size_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
  85int 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
 135const void *fdt_offset_ptr(const void *fdt, int offset, unsigned int len)
 136{
 137        unsigned absoffset = offset + fdt_off_dt_struct(fdt);
 138
 139        if (!can_assume(VALID_INPUT))
 140                if ((absoffset < offset)
 141                    || ((absoffset + len) < absoffset)
 142                    || (absoffset + len) > fdt_totalsize(fdt))
 143                        return NULL;
 144
 145        if (can_assume(LATEST) || fdt_version(fdt) >= 0x11)
 146                if (((offset + len) < offset)
 147                    || ((offset + len) > fdt_size_dt_struct(fdt)))
 148                        return NULL;
 149
 150        return fdt_offset_ptr_(fdt, offset);
 151}
 152
 153uint32_t fdt_next_tag(const void *fdt, int startoffset, int *nextoffset)
 154{
 155        const fdt32_t *tagp, *lenp;
 156        uint32_t tag;
 157        int offset = startoffset;
 158        const char *p;
 159
 160        *nextoffset = -FDT_ERR_TRUNCATED;
 161        tagp = fdt_offset_ptr(fdt, offset, FDT_TAGSIZE);
 162        if (!can_assume(VALID_DTB) && !tagp)
 163                return FDT_END; /* premature end */
 164        tag = fdt32_to_cpu(*tagp);
 165        offset += FDT_TAGSIZE;
 166
 167        *nextoffset = -FDT_ERR_BADSTRUCTURE;
 168        switch (tag) {
 169        case FDT_BEGIN_NODE:
 170                /* skip name */
 171                do {
 172                        p = fdt_offset_ptr(fdt, offset++, 1);
 173                } while (p && (*p != '\0'));
 174                if (!can_assume(VALID_DTB) && !p)
 175                        return FDT_END; /* premature end */
 176                break;
 177
 178        case FDT_PROP:
 179                lenp = fdt_offset_ptr(fdt, offset, sizeof(*lenp));
 180                if (!can_assume(VALID_DTB) && !lenp)
 181                        return FDT_END; /* premature end */
 182                /* skip-name offset, length and value */
 183                offset += sizeof(struct fdt_property) - FDT_TAGSIZE
 184                        + fdt32_to_cpu(*lenp);
 185                if (!can_assume(LATEST) &&
 186                    fdt_version(fdt) < 0x10 && fdt32_to_cpu(*lenp) >= 8 &&
 187                    ((offset - fdt32_to_cpu(*lenp)) % 8) != 0)
 188                        offset += 4;
 189                break;
 190
 191        case FDT_END:
 192        case FDT_END_NODE:
 193        case FDT_NOP:
 194                break;
 195
 196        default:
 197                return FDT_END;
 198        }
 199
 200        if (!fdt_offset_ptr(fdt, startoffset, offset - startoffset))
 201                return FDT_END; /* premature end */
 202
 203        *nextoffset = FDT_TAGALIGN(offset);
 204        return tag;
 205}
 206
 207int fdt_check_node_offset_(const void *fdt, int offset)
 208{
 209        if (can_assume(VALID_INPUT))
 210                return offset;
 211        if ((offset < 0) || (offset % FDT_TAGSIZE)
 212            || (fdt_next_tag(fdt, offset, &offset) != FDT_BEGIN_NODE))
 213                return -FDT_ERR_BADOFFSET;
 214
 215        return offset;
 216}
 217
 218int fdt_check_prop_offset_(const void *fdt, int offset)
 219{
 220        if ((offset < 0) || (offset % FDT_TAGSIZE)
 221            || (fdt_next_tag(fdt, offset, &offset) != FDT_PROP))
 222                return -FDT_ERR_BADOFFSET;
 223
 224        return offset;
 225}
 226
 227int fdt_next_node(const void *fdt, int offset, int *depth)
 228{
 229        int nextoffset = 0;
 230        uint32_t tag;
 231
 232        if (offset >= 0)
 233                if ((nextoffset = fdt_check_node_offset_(fdt, offset)) < 0)
 234                        return nextoffset;
 235
 236        do {
 237                offset = nextoffset;
 238                tag = fdt_next_tag(fdt, offset, &nextoffset);
 239
 240                switch (tag) {
 241                case FDT_PROP:
 242                case FDT_NOP:
 243                        break;
 244
 245                case FDT_BEGIN_NODE:
 246                        if (depth)
 247                                (*depth)++;
 248                        break;
 249
 250                case FDT_END_NODE:
 251                        if (depth && ((--(*depth)) < 0))
 252                                return nextoffset;
 253                        break;
 254
 255                case FDT_END:
 256                        if ((nextoffset >= 0)
 257                            || ((nextoffset == -FDT_ERR_TRUNCATED) && !depth))
 258                                return -FDT_ERR_NOTFOUND;
 259                        else
 260                                return nextoffset;
 261                }
 262        } while (tag != FDT_BEGIN_NODE);
 263
 264        return offset;
 265}
 266
 267int fdt_first_subnode(const void *fdt, int offset)
 268{
 269        int depth = 0;
 270
 271        offset = fdt_next_node(fdt, offset, &depth);
 272        if (offset < 0 || depth != 1)
 273                return -FDT_ERR_NOTFOUND;
 274
 275        return offset;
 276}
 277
 278int fdt_next_subnode(const void *fdt, int offset)
 279{
 280        int depth = 1;
 281
 282        /*
 283         * With respect to the parent, the depth of the next subnode will be
 284         * the same as the last.
 285         */
 286        do {
 287                offset = fdt_next_node(fdt, offset, &depth);
 288                if (offset < 0 || depth < 1)
 289                        return -FDT_ERR_NOTFOUND;
 290        } while (depth > 1);
 291
 292        return offset;
 293}
 294
 295const char *fdt_find_string_(const char *strtab, int tabsize, const char *s)
 296{
 297        int len = strlen(s) + 1;
 298        const char *last = strtab + tabsize - len;
 299        const char *p;
 300
 301        for (p = strtab; p <= last; p++)
 302                if (memcmp(p, s, len) == 0)
 303                        return p;
 304        return NULL;
 305}
 306
 307int fdt_move(const void *fdt, void *buf, int bufsize)
 308{
 309        FDT_RO_PROBE(fdt);
 310
 311        if (fdt_totalsize(fdt) > bufsize)
 312                return -FDT_ERR_NOSPACE;
 313
 314        memmove(buf, fdt, fdt_totalsize(fdt));
 315        return 0;
 316}
 317