fdt.c

Go to the documentation of this file.

// 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;
}