dtc/libfdt/fdt.c

0001 // SPDX-License-Identifier: (GPL-2.0-or-later OR BSD-2-Clause)
0002 /*
0003  * libfdt - Flat Device Tree manipulation
0004  * Copyright (C) 2006 David Gibson, IBM Corporation.
0005  */
0006 #include "libfdt_env.h"
0007
0008 #include <fdt.h>
0009 #include <libfdt.h>
0010
0011 #include "libfdt_internal.h"
0012
0013 /*
0014  * Minimal sanity check for a read-only tree. fdt_ro_probe_() checks
0015  * that the given buffer contains what appears to be a flattened
0016  * device tree with sane information in its header.
0017  */
0018 int32_t fdt_ro_probe_(const void *fdt)
0019 {
0020     uint32_t totalsize = fdt_totalsize(fdt);
0021
0022     if (can_assume(VALID_DTB))
0023         return totalsize;
0024
0025     /* The device tree must be at an 8-byte aligned address */
0026     if ((uintptr_t)fdt & 7)
0027         return -FDT_ERR_ALIGNMENT;
0028
0029     if (fdt_magic(fdt) == FDT_MAGIC) {
0030         /* Complete tree */
0031         if (!can_assume(LATEST)) {
0032             if (fdt_version(fdt) < FDT_FIRST_SUPPORTED_VERSION)
0033                 return -FDT_ERR_BADVERSION;
0034             if (fdt_last_comp_version(fdt) >
0035                     FDT_LAST_SUPPORTED_VERSION)
0036                 return -FDT_ERR_BADVERSION;
0037         }
0038     } else if (fdt_magic(fdt) == FDT_SW_MAGIC) {
0039         /* Unfinished sequential-write blob */
0040         if (!can_assume(VALID_INPUT) && fdt_size_dt_struct(fdt) == 0)
0041             return -FDT_ERR_BADSTATE;
0042     } else {
0043         return -FDT_ERR_BADMAGIC;
0044     }
0045
0046     if (totalsize < INT32_MAX)
0047         return totalsize;
0048     else
0049         return -FDT_ERR_TRUNCATED;
0050 }
0051
0052 static int check_off_(uint32_t hdrsize, uint32_t totalsize, uint32_t off)
0053 {
0054     return (off >= hdrsize) && (off <= totalsize);
0055 }
0056
0057 static int check_block_(uint32_t hdrsize, uint32_t totalsize,
0058             uint32_t base, uint32_t size)
0059 {
0060     if (!check_off_(hdrsize, totalsize, base))
0061         return 0; /* block start out of bounds */
0062     if ((base + size) < base)
0063         return 0; /* overflow */
0064     if (!check_off_(hdrsize, totalsize, base + size))
0065         return 0; /* block end out of bounds */
0066     return 1;
0067 }
0068
0069 size_t fdt_header_size_(uint32_t version)
0070 {
0071     if (version <= 1)
0072         return FDT_V1_SIZE;
0073     else if (version <= 2)
0074         return FDT_V2_SIZE;
0075     else if (version <= 3)
0076         return FDT_V3_SIZE;
0077     else if (version <= 16)
0078         return FDT_V16_SIZE;
0079     else
0080         return FDT_V17_SIZE;
0081 }
0082
0083 size_t fdt_header_size(const void *fdt)
0084 {
0085     return can_assume(LATEST) ? FDT_V17_SIZE :
0086         fdt_header_size_(fdt_version(fdt));
0087 }
0088
0089 int fdt_check_header(const void *fdt)
0090 {
0091     size_t hdrsize;
0092
0093     /* The device tree must be at an 8-byte aligned address */
0094     if ((uintptr_t)fdt & 7)
0095         return -FDT_ERR_ALIGNMENT;
0096
0097     if (fdt_magic(fdt) != FDT_MAGIC)
0098         return -FDT_ERR_BADMAGIC;
0099     if (!can_assume(LATEST)) {
0100         if ((fdt_version(fdt) < FDT_FIRST_SUPPORTED_VERSION)
0101             || (fdt_last_comp_version(fdt) >
0102             FDT_LAST_SUPPORTED_VERSION))
0103             return -FDT_ERR_BADVERSION;
0104         if (fdt_version(fdt) < fdt_last_comp_version(fdt))
0105             return -FDT_ERR_BADVERSION;
0106     }
0107     hdrsize = fdt_header_size(fdt);
0108     if (!can_assume(VALID_DTB)) {
0109         if ((fdt_totalsize(fdt) < hdrsize)
0110             || (fdt_totalsize(fdt) > INT_MAX))
0111             return -FDT_ERR_TRUNCATED;
0112
0113         /* Bounds check memrsv block */
0114         if (!check_off_(hdrsize, fdt_totalsize(fdt),
0115                 fdt_off_mem_rsvmap(fdt)))
0116             return -FDT_ERR_TRUNCATED;
0117
0118         /* Bounds check structure block */
0119         if (!can_assume(LATEST) && fdt_version(fdt) < 17) {
0120             if (!check_off_(hdrsize, fdt_totalsize(fdt),
0121                     fdt_off_dt_struct(fdt)))
0122                 return -FDT_ERR_TRUNCATED;
0123         } else {
0124             if (!check_block_(hdrsize, fdt_totalsize(fdt),
0125                       fdt_off_dt_struct(fdt),
0126                       fdt_size_dt_struct(fdt)))
0127                 return -FDT_ERR_TRUNCATED;
0128         }
0129
0130         /* Bounds check strings block */
0131         if (!check_block_(hdrsize, fdt_totalsize(fdt),
0132                   fdt_off_dt_strings(fdt),
0133                   fdt_size_dt_strings(fdt)))
0134             return -FDT_ERR_TRUNCATED;
0135     }
0136
0137     return 0;
0138 }
0139
0140 const void *fdt_offset_ptr(const void *fdt, int offset, unsigned int len)
0141 {
0142     unsigned int uoffset = offset;
0143     unsigned int absoffset = offset + fdt_off_dt_struct(fdt);
0144
0145     if (offset < 0)
0146         return NULL;
0147
0148     if (!can_assume(VALID_INPUT))
0149         if ((absoffset < uoffset)
0150             || ((absoffset + len) < absoffset)
0151             || (absoffset + len) > fdt_totalsize(fdt))
0152             return NULL;
0153
0154     if (can_assume(LATEST) || fdt_version(fdt) >= 0x11)
0155         if (((uoffset + len) < uoffset)
0156             || ((offset + len) > fdt_size_dt_struct(fdt)))
0157             return NULL;
0158
0159     return fdt_offset_ptr_(fdt, offset);
0160 }
0161
0162 uint32_t fdt_next_tag(const void *fdt, int startoffset, int *nextoffset)
0163 {
0164     const fdt32_t *tagp, *lenp;
0165     uint32_t tag, len, sum;
0166     int offset = startoffset;
0167     const char *p;
0168
0169     *nextoffset = -FDT_ERR_TRUNCATED;
0170     tagp = fdt_offset_ptr(fdt, offset, FDT_TAGSIZE);
0171     if (!can_assume(VALID_DTB) && !tagp)
0172         return FDT_END; /* premature end */
0173     tag = fdt32_to_cpu(*tagp);
0174     offset += FDT_TAGSIZE;
0175
0176     *nextoffset = -FDT_ERR_BADSTRUCTURE;
0177     switch (tag) {
0178     case FDT_BEGIN_NODE:
0179         /* skip name */
0180         do {
0181             p = fdt_offset_ptr(fdt, offset++, 1);
0182         } while (p && (*p != '\0'));
0183         if (!can_assume(VALID_DTB) && !p)
0184             return FDT_END; /* premature end */
0185         break;
0186
0187     case FDT_PROP:
0188         lenp = fdt_offset_ptr(fdt, offset, sizeof(*lenp));
0189         if (!can_assume(VALID_DTB) && !lenp)
0190             return FDT_END; /* premature end */
0191
0192         len = fdt32_to_cpu(*lenp);
0193         sum = len + offset;
0194         if (!can_assume(VALID_DTB) &&
0195             (INT_MAX <= sum || sum < (uint32_t) offset))
0196             return FDT_END; /* premature end */
0197
0198         /* skip-name offset, length and value */
0199         offset += sizeof(struct fdt_property) - FDT_TAGSIZE + len;
0200
0201         if (!can_assume(LATEST) &&
0202             fdt_version(fdt) < 0x10 && len >= 8 &&
0203             ((offset - len) % 8) != 0)
0204             offset += 4;
0205         break;
0206
0207     case FDT_END:
0208     case FDT_END_NODE:
0209     case FDT_NOP:
0210         break;
0211
0212     default:
0213         return FDT_END;
0214     }
0215
0216     if (!fdt_offset_ptr(fdt, startoffset, offset - startoffset))
0217         return FDT_END; /* premature end */
0218
0219     *nextoffset = FDT_TAGALIGN(offset);
0220     return tag;
0221 }
0222
0223 int fdt_check_node_offset_(const void *fdt, int offset)
0224 {
0225     if (!can_assume(VALID_INPUT)
0226         && ((offset < 0) || (offset % FDT_TAGSIZE)))
0227         return -FDT_ERR_BADOFFSET;
0228
0229     if (fdt_next_tag(fdt, offset, &offset) != FDT_BEGIN_NODE)
0230         return -FDT_ERR_BADOFFSET;
0231
0232     return offset;
0233 }
0234
0235 int fdt_check_prop_offset_(const void *fdt, int offset)
0236 {
0237     if (!can_assume(VALID_INPUT)
0238         && ((offset < 0) || (offset % FDT_TAGSIZE)))
0239         return -FDT_ERR_BADOFFSET;
0240
0241     if (fdt_next_tag(fdt, offset, &offset) != FDT_PROP)
0242         return -FDT_ERR_BADOFFSET;
0243
0244     return offset;
0245 }
0246
0247 int fdt_next_node(const void *fdt, int offset, int *depth)
0248 {
0249     int nextoffset = 0;
0250     uint32_t tag;
0251
0252     if (offset >= 0)
0253         if ((nextoffset = fdt_check_node_offset_(fdt, offset)) < 0)
0254             return nextoffset;
0255
0256     do {
0257         offset = nextoffset;
0258         tag = fdt_next_tag(fdt, offset, &nextoffset);
0259
0260         switch (tag) {
0261         case FDT_PROP:
0262         case FDT_NOP:
0263             break;
0264
0265         case FDT_BEGIN_NODE:
0266             if (depth)
0267                 (*depth)++;
0268             break;
0269
0270         case FDT_END_NODE:
0271             if (depth && ((--(*depth)) < 0))
0272                 return nextoffset;
0273             break;
0274
0275         case FDT_END:
0276             if ((nextoffset >= 0)
0277                 || ((nextoffset == -FDT_ERR_TRUNCATED) && !depth))
0278                 return -FDT_ERR_NOTFOUND;
0279             else
0280                 return nextoffset;
0281         }
0282     } while (tag != FDT_BEGIN_NODE);
0283
0284     return offset;
0285 }
0286
0287 int fdt_first_subnode(const void *fdt, int offset)
0288 {
0289     int depth = 0;
0290
0291     offset = fdt_next_node(fdt, offset, &depth);
0292     if (offset < 0 || depth != 1)
0293         return -FDT_ERR_NOTFOUND;
0294
0295     return offset;
0296 }
0297
0298 int fdt_next_subnode(const void *fdt, int offset)
0299 {
0300     int depth = 1;
0301
0302     /*
0303      * With respect to the parent, the depth of the next subnode will be
0304      * the same as the last.
0305      */
0306     do {
0307         offset = fdt_next_node(fdt, offset, &depth);
0308         if (offset < 0 || depth < 1)
0309             return -FDT_ERR_NOTFOUND;
0310     } while (depth > 1);
0311
0312     return offset;
0313 }
0314
0315 const char *fdt_find_string_(const char *strtab, int tabsize, const char *s)
0316 {
0317     int len = strlen(s) + 1;
0318     const char *last = strtab + tabsize - len;
0319     const char *p;
0320
0321     for (p = strtab; p <= last; p++)
0322         if (memcmp(p, s, len) == 0)
0323             return p;
0324     return NULL;
0325 }
0326
0327 int fdt_move(const void *fdt, void *buf, int bufsize)
0328 {
0329     if (!can_assume(VALID_INPUT) && bufsize < 0)
0330         return -FDT_ERR_NOSPACE;
0331
0332     FDT_RO_PROBE(fdt);
0333
0334     if (fdt_totalsize(fdt) > (unsigned int)bufsize)
0335         return -FDT_ERR_NOSPACE;
0336
0337     memmove(buf, fdt, fdt_totalsize(fdt));
0338     return 0;
0339 }