source: rtems/cpukit/dtc/libfdt/fdt.c

// SPDX-License-Identifier: (GPL-2.0-or-later OR BSD-2-Clause)
/*
 * libfdt - Flat Device Tree manipulation
 * Copyright (C) 2006 David Gibson, IBM Corporation.
 */
#include "libfdt_env.h"

#include <fdt.h>
#include <libfdt.h>

#include "libfdt_internal.h"

/*
 * Minimal sanity check for a read-only tree. fdt_ro_probe_() checks
 * that the given buffer contains what appears to be a flattened
 * device tree with sane information in its header.
 */
int32_t fdt_ro_probe_(const void *fdt)
{
        uint32_t totalsize = fdt_totalsize(fdt);

        if (can_assume(VALID_DTB))
                return totalsize;

        /* The device tree must be at an 8-byte aligned address */
        if ((uintptr_t)fdt & 7)
                return -FDT_ERR_ALIGNMENT;

        if (fdt_magic(fdt) == FDT_MAGIC) {
                /* Complete tree */
                if (!can_assume(LATEST)) {
                        if (fdt_version(fdt) < FDT_FIRST_SUPPORTED_VERSION)
                                return -FDT_ERR_BADVERSION;
                        if (fdt_last_comp_version(fdt) >
                                        FDT_LAST_SUPPORTED_VERSION)
                                return -FDT_ERR_BADVERSION;
                }
        } else if (fdt_magic(fdt) == FDT_SW_MAGIC) {
                /* Unfinished sequential-write blob */
                if (!can_assume(VALID_INPUT) && fdt_size_dt_struct(fdt) == 0)
                        return -FDT_ERR_BADSTATE;
        } else {
                return -FDT_ERR_BADMAGIC;
        }

        if (totalsize < INT32_MAX)
                return totalsize;
        else
                return -FDT_ERR_TRUNCATED;
}

static int check_off_(uint32_t hdrsize, uint32_t totalsize, uint32_t off)
{
        return (off >= hdrsize) && (off <= totalsize);
}

static int check_block_(uint32_t hdrsize, uint32_t totalsize,
                        uint32_t base, uint32_t size)
{
        if (!check_off_(hdrsize, totalsize, base))
                return 0; /* block start out of bounds */
        if ((base + size) < base)
                return 0; /* overflow */
        if (!check_off_(hdrsize, totalsize, base + size))
                return 0; /* block end out of bounds */
        return 1;
}

size_t fdt_header_size_(uint32_t version)
{
        if (version <= 1)
                return FDT_V1_SIZE;
        else if (version <= 2)
                return FDT_V2_SIZE;
        else if (version <= 3)
                return FDT_V3_SIZE;
        else if (version <= 16)
                return FDT_V16_SIZE;
        else
                return FDT_V17_SIZE;
}

size_t fdt_header_size(const void *fdt)
{
        return can_assume(LATEST) ? FDT_V17_SIZE :
                fdt_header_size_(fdt_version(fdt));
}

int fdt_check_header(const void *fdt)
{
        size_t hdrsize;

        /* The device tree must be at an 8-byte aligned address */
        if ((uintptr_t)fdt & 7)
                return -FDT_ERR_ALIGNMENT;

        if (fdt_magic(fdt) != FDT_MAGIC)
                return -FDT_ERR_BADMAGIC;
        if (!can_assume(LATEST)) {
                if ((fdt_version(fdt) < FDT_FIRST_SUPPORTED_VERSION)
                    || (fdt_last_comp_version(fdt) >
                        FDT_LAST_SUPPORTED_VERSION))
                        return -FDT_ERR_BADVERSION;
                if (fdt_version(fdt) < fdt_last_comp_version(fdt))
                        return -FDT_ERR_BADVERSION;
        }
        hdrsize = fdt_header_size(fdt);
        if (!can_assume(VALID_DTB)) {
                if ((fdt_totalsize(fdt) < hdrsize)
                    || (fdt_totalsize(fdt) > INT_MAX))
                        return -FDT_ERR_TRUNCATED;

                /* Bounds check memrsv block */
                if (!check_off_(hdrsize, fdt_totalsize(fdt),
                                fdt_off_mem_rsvmap(fdt)))
                        return -FDT_ERR_TRUNCATED;

                /* Bounds check structure block */
                if (!can_assume(LATEST) && fdt_version(fdt) < 17) {
                        if (!check_off_(hdrsize, fdt_totalsize(fdt),
                                        fdt_off_dt_struct(fdt)))
                                return -FDT_ERR_TRUNCATED;
                } else {
                        if (!check_block_(hdrsize, fdt_totalsize(fdt),
                                          fdt_off_dt_struct(fdt),
                                          fdt_size_dt_struct(fdt)))
                                return -FDT_ERR_TRUNCATED;
                }

                /* Bounds check strings block */
                if (!check_block_(hdrsize, fdt_totalsize(fdt),
                                  fdt_off_dt_strings(fdt),
                                  fdt_size_dt_strings(fdt)))
                        return -FDT_ERR_TRUNCATED;
        }

        return 0;
}

const void *fdt_offset_ptr(const void *fdt, int offset, unsigned int len)
{
        unsigned int uoffset = offset;
        unsigned int absoffset = offset + fdt_off_dt_struct(fdt);

        if (offset < 0)
                return NULL;

        if (!can_assume(VALID_INPUT))
                if ((absoffset < uoffset)
                    || ((absoffset + len) < absoffset)
                    || (absoffset + len) > fdt_totalsize(fdt))
                        return NULL;

        if (can_assume(LATEST) || fdt_version(fdt) >= 0x11)
                if (((uoffset + len) < uoffset)
                    || ((offset + len) > fdt_size_dt_struct(fdt)))
                        return NULL;

        return fdt_offset_ptr_(fdt, offset);
}

uint32_t fdt_next_tag(const void *fdt, int startoffset, int *nextoffset)
{
        const fdt32_t *tagp, *lenp;
        uint32_t tag, len, sum;
        int offset = startoffset;
        const char *p;

        *nextoffset = -FDT_ERR_TRUNCATED;
        tagp = fdt_offset_ptr(fdt, offset, FDT_TAGSIZE);
        if (!can_assume(VALID_DTB) && !tagp)
                return FDT_END; /* premature end */
        tag = fdt32_to_cpu(*tagp);
        offset += FDT_TAGSIZE;

        *nextoffset = -FDT_ERR_BADSTRUCTURE;
        switch (tag) {
        case FDT_BEGIN_NODE:
                /* skip name */
                do {
                        p = fdt_offset_ptr(fdt, offset++, 1);
                } while (p && (*p != '\0'));
                if (!can_assume(VALID_DTB) && !p)
                        return FDT_END; /* premature end */
                break;

        case FDT_PROP:
                lenp = fdt_offset_ptr(fdt, offset, sizeof(*lenp));
                if (!can_assume(VALID_DTB) && !lenp)
                        return FDT_END; /* premature end */

                len = fdt32_to_cpu(*lenp);
                sum = len + offset;
                if (!can_assume(VALID_DTB) &&
                    (INT_MAX <= sum || sum < (uint32_t) offset))
                        return FDT_END; /* premature end */

                /* skip-name offset, length and value */
                offset += sizeof(struct fdt_property) - FDT_TAGSIZE + len;

                if (!can_assume(LATEST) &&
                    fdt_version(fdt) < 0x10 && len >= 8 &&
                    ((offset - len) % 8) != 0)
                        offset += 4;
                break;

        case FDT_END:
        case FDT_END_NODE:
        case FDT_NOP:
                break;

        default:
                return FDT_END;
        }

        if (!fdt_offset_ptr(fdt, startoffset, offset - startoffset))
                return FDT_END; /* premature end */

        *nextoffset = FDT_TAGALIGN(offset);
        return tag;
}

int fdt_check_node_offset_(const void *fdt, int offset)
{
        if (!can_assume(VALID_INPUT)
            && ((offset < 0) || (offset % FDT_TAGSIZE)))
                return -FDT_ERR_BADOFFSET;

        if (fdt_next_tag(fdt, offset, &offset) != FDT_BEGIN_NODE)
                return -FDT_ERR_BADOFFSET;

        return offset;
}

int fdt_check_prop_offset_(const void *fdt, int offset)
{
        if (!can_assume(VALID_INPUT)
            && ((offset < 0) || (offset % FDT_TAGSIZE)))
                return -FDT_ERR_BADOFFSET;

        if (fdt_next_tag(fdt, offset, &offset) != FDT_PROP)
                return -FDT_ERR_BADOFFSET;

        return offset;
}

int fdt_next_node(const void *fdt, int offset, int *depth)
{
        int nextoffset = 0;
        uint32_t tag;

        if (offset >= 0)
                if ((nextoffset = fdt_check_node_offset_(fdt, offset)) < 0)
                        return nextoffset;

        do {
                offset = nextoffset;
                tag = fdt_next_tag(fdt, offset, &nextoffset);

                switch (tag) {
                case FDT_PROP:
                case FDT_NOP:
                        break;

                case FDT_BEGIN_NODE:
                        if (depth)
                                (*depth)++;
                        break;

                case FDT_END_NODE:
                        if (depth && ((--(*depth)) < 0))
                                return nextoffset;
                        break;

                case FDT_END:
                        if ((nextoffset >= 0)
                            || ((nextoffset == -FDT_ERR_TRUNCATED) && !depth))
                                return -FDT_ERR_NOTFOUND;
                        else
                                return nextoffset;
                }
        } while (tag != FDT_BEGIN_NODE);

        return offset;
}

int fdt_first_subnode(const void *fdt, int offset)
{
        int depth = 0;

        offset = fdt_next_node(fdt, offset, &depth);
        if (offset < 0 || depth != 1)
                return -FDT_ERR_NOTFOUND;

        return offset;
}

int fdt_next_subnode(const void *fdt, int offset)
{
        int depth = 1;

        /*
         * With respect to the parent, the depth of the next subnode will be
         * the same as the last.
         */
        do {
                offset = fdt_next_node(fdt, offset, &depth);
                if (offset < 0 || depth < 1)
                        return -FDT_ERR_NOTFOUND;
        } while (depth > 1);

        return offset;
}

const char *fdt_find_string_(const char *strtab, int tabsize, const char *s)
{
        int len = strlen(s) + 1;
        const char *last = strtab + tabsize - len;
        const char *p;

        for (p = strtab; p <= last; p++)
                if (memcmp(p, s, len) == 0)
                        return p;
        return NULL;
}

int fdt_move(const void *fdt, void *buf, int bufsize)
{
        if (!can_assume(VALID_INPUT) && bufsize < 0)
                return -FDT_ERR_NOSPACE;

        FDT_RO_PROBE(fdt);

        if (fdt_totalsize(fdt) > (unsigned int)bufsize)
                return -FDT_ERR_NOSPACE;

        memmove(buf, fdt, fdt_totalsize(fdt));
        return 0;
}