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
0110         if ((fdt_totalsize(fdt) < hdrsize)
0111             || (fdt_totalsize(fdt) > INT_MAX))
0112             return -FDT_ERR_TRUNCATED;
0113
0114         /* Bounds check memrsv block */
0115         if (!check_off_(hdrsize, fdt_totalsize(fdt),
0116                 fdt_off_mem_rsvmap(fdt)))
0117             return -FDT_ERR_TRUNCATED;
0118     }
0119
0120     if (!can_assume(VALID_DTB)) {
0121         /* Bounds check structure block */
0122         if (!can_assume(LATEST) && fdt_version(fdt) < 17) {
0123             if (!check_off_(hdrsize, fdt_totalsize(fdt),
0124                     fdt_off_dt_struct(fdt)))
0125                 return -FDT_ERR_TRUNCATED;
0126         } else {
0127             if (!check_block_(hdrsize, fdt_totalsize(fdt),
0128                       fdt_off_dt_struct(fdt),
0129                       fdt_size_dt_struct(fdt)))
0130                 return -FDT_ERR_TRUNCATED;
0131         }
0132
0133         /* Bounds check strings block */
0134         if (!check_block_(hdrsize, fdt_totalsize(fdt),
0135                   fdt_off_dt_strings(fdt),
0136                   fdt_size_dt_strings(fdt)))
0137             return -FDT_ERR_TRUNCATED;
0138     }
0139
0140     return 0;
0141 }
0142
0143 const void *fdt_offset_ptr(const void *fdt, int offset, unsigned int len)
0144 {
0145     unsigned int uoffset = offset;
0146     unsigned int absoffset = offset + fdt_off_dt_struct(fdt);
0147
0148     if (offset < 0)
0149         return NULL;
0150
0151     if (!can_assume(VALID_INPUT))
0152         if ((absoffset < uoffset)
0153             || ((absoffset + len) < absoffset)
0154             || (absoffset + len) > fdt_totalsize(fdt))
0155             return NULL;
0156
0157     if (can_assume(LATEST) || fdt_version(fdt) >= 0x11)
0158         if (((uoffset + len) < uoffset)
0159             || ((offset + len) > fdt_size_dt_struct(fdt)))
0160             return NULL;
0161
0162     return fdt_offset_ptr_(fdt, offset);
0163 }
0164
0165 uint32_t fdt_next_tag(const void *fdt, int startoffset, int *nextoffset)
0166 {
0167     const fdt32_t *tagp, *lenp;
0168     uint32_t tag;
0169     int offset = startoffset;
0170     const char *p;
0171
0172     *nextoffset = -FDT_ERR_TRUNCATED;
0173     tagp = fdt_offset_ptr(fdt, offset, FDT_TAGSIZE);
0174     if (!can_assume(VALID_DTB) && !tagp)
0175         return FDT_END; /* premature end */
0176     tag = fdt32_to_cpu(*tagp);
0177     offset += FDT_TAGSIZE;
0178
0179     *nextoffset = -FDT_ERR_BADSTRUCTURE;
0180     switch (tag) {
0181     case FDT_BEGIN_NODE:
0182         /* skip name */
0183         do {
0184             p = fdt_offset_ptr(fdt, offset++, 1);
0185         } while (p && (*p != '\0'));
0186         if (!can_assume(VALID_DTB) && !p)
0187             return FDT_END; /* premature end */
0188         break;
0189
0190     case FDT_PROP:
0191         lenp = fdt_offset_ptr(fdt, offset, sizeof(*lenp));
0192         if (!can_assume(VALID_DTB) && !lenp)
0193             return FDT_END; /* premature end */
0194         /* skip-name offset, length and value */
0195         offset += sizeof(struct fdt_property) - FDT_TAGSIZE
0196             + fdt32_to_cpu(*lenp);
0197         if (!can_assume(LATEST) &&
0198             fdt_version(fdt) < 0x10 && fdt32_to_cpu(*lenp) >= 8 &&
0199             ((offset - fdt32_to_cpu(*lenp)) % 8) != 0)
0200             offset += 4;
0201         break;
0202
0203     case FDT_END:
0204     case FDT_END_NODE:
0205     case FDT_NOP:
0206         break;
0207
0208     default:
0209         return FDT_END;
0210     }
0211
0212     if (!fdt_offset_ptr(fdt, startoffset, offset - startoffset))
0213         return FDT_END; /* premature end */
0214
0215     *nextoffset = FDT_TAGALIGN(offset);
0216     return tag;
0217 }
0218
0219 int fdt_check_node_offset_(const void *fdt, int offset)
0220 {
0221     if (!can_assume(VALID_INPUT)
0222         && ((offset < 0) || (offset % FDT_TAGSIZE)))
0223         return -FDT_ERR_BADOFFSET;
0224
0225     if (fdt_next_tag(fdt, offset, &offset) != FDT_BEGIN_NODE)
0226         return -FDT_ERR_BADOFFSET;
0227
0228     return offset;
0229 }
0230
0231 int fdt_check_prop_offset_(const void *fdt, int offset)
0232 {
0233     if (!can_assume(VALID_INPUT)
0234         && ((offset < 0) || (offset % FDT_TAGSIZE)))
0235         return -FDT_ERR_BADOFFSET;
0236
0237     if (fdt_next_tag(fdt, offset, &offset) != FDT_PROP)
0238         return -FDT_ERR_BADOFFSET;
0239
0240     return offset;
0241 }
0242
0243 int fdt_next_node(const void *fdt, int offset, int *depth)
0244 {
0245     int nextoffset = 0;
0246     uint32_t tag;
0247
0248     if (offset >= 0)
0249         if ((nextoffset = fdt_check_node_offset_(fdt, offset)) < 0)
0250             return nextoffset;
0251
0252     do {
0253         offset = nextoffset;
0254         tag = fdt_next_tag(fdt, offset, &nextoffset);
0255
0256         switch (tag) {
0257         case FDT_PROP:
0258         case FDT_NOP:
0259             break;
0260
0261         case FDT_BEGIN_NODE:
0262             if (depth)
0263                 (*depth)++;
0264             break;
0265
0266         case FDT_END_NODE:
0267             if (depth && ((--(*depth)) < 0))
0268                 return nextoffset;
0269             break;
0270
0271         case FDT_END:
0272             if ((nextoffset >= 0)
0273                 || ((nextoffset == -FDT_ERR_TRUNCATED) && !depth))
0274                 return -FDT_ERR_NOTFOUND;
0275             else
0276                 return nextoffset;
0277         }
0278     } while (tag != FDT_BEGIN_NODE);
0279
0280     return offset;
0281 }
0282
0283 int fdt_first_subnode(const void *fdt, int offset)
0284 {
0285     int depth = 0;
0286
0287     offset = fdt_next_node(fdt, offset, &depth);
0288     if (offset < 0 || depth != 1)
0289         return -FDT_ERR_NOTFOUND;
0290
0291     return offset;
0292 }
0293
0294 int fdt_next_subnode(const void *fdt, int offset)
0295 {
0296     int depth = 1;
0297
0298     /*
0299      * With respect to the parent, the depth of the next subnode will be
0300      * the same as the last.
0301      */
0302     do {
0303         offset = fdt_next_node(fdt, offset, &depth);
0304         if (offset < 0 || depth < 1)
0305             return -FDT_ERR_NOTFOUND;
0306     } while (depth > 1);
0307
0308     return offset;
0309 }
0310
0311 const char *fdt_find_string_(const char *strtab, int tabsize, const char *s)
0312 {
0313     int len = strlen(s) + 1;
0314     const char *last = strtab + tabsize - len;
0315     const char *p;
0316
0317     for (p = strtab; p <= last; p++)
0318         if (memcmp(p, s, len) == 0)
0319             return p;
0320     return NULL;
0321 }
0322
0323 int fdt_move(const void *fdt, void *buf, int bufsize)
0324 {
0325     if (!can_assume(VALID_INPUT) && bufsize < 0)
0326         return -FDT_ERR_NOSPACE;
0327
0328     FDT_RO_PROBE(fdt);
0329
0330     if (fdt_totalsize(fdt) > (unsigned int)bufsize)
0331         return -FDT_ERR_NOSPACE;
0332
0333     memmove(buf, fdt, fdt_totalsize(fdt));
0334     return 0;
0335 }