bflt.c File Reference

#include <rz_util.h>
#include <rz_types.h>
#include "bflt.h"

Go to the source code of this file.

Macros
#define	MAX_SHARED_LIBS   1
#define	FLAT_DATA_ALIGN   0x20
#define	READ(x, i)

Functions
static bool	bflt_init_hdr (RzBfltObj *bin)
static bool	bflt_reloc_big_endian (RzBfltObj *bin)
static void	bflt_load_relocs (RzBfltObj *bin)
static void	patch_relocs_in (RzBfltObj *bin, RzVector *relocs)
static void	bflt_patch_relocs (RzBfltObj *bin)
static bool	rz_bflt_init (RzBfltObj *obj, RzBuffer *buf, ut64 baddr, bool big_endian, bool patch_relocs)
RzBfltObj *	rz_bflt_new_buf (RzBuffer *buf, ut64 baddr, bool big_endian, bool patch_relocs)
void	rz_bflt_free (RzBfltObj *obj)
RzBinAddr *	rz_bflt_get_entry (RzBfltObj *bin)
ut64	rz_bflt_get_text_base (RzBfltObj *bin)
	Address to map text segment to. More...
ut64	rz_bflt_get_data_base (RzBfltObj *bin)
	Address to map data+bss segment to. More...
ut64	rz_bflt_get_data_vsize (RzBfltObj *bin)
	Total size of data+bss. More...
ut64	rz_bflt_paddr_to_vaddr (RzBfltObj *bin, ut32 paddr)

Detailed Description

uClinux bFLT file format For reference, see linux/include/uapi/linux/flat.h linux/fs/binfmt_flat.c in the uClinux kernel, e.g. from uClinux-dist-20160919

Definition in file bflt.c.

Macro Definition Documentation

FLAT_DATA_ALIGN

#define FLAT_DATA_ALIGN   0x20

Definition at line 20 of file bflt.c.

MAX_SHARED_LIBS

#define MAX_SHARED_LIBS   1

Definition at line 19 of file bflt.c.

READ

#define READ	(		x,
			i
	)

Value:

    rz_read_be32((x) + (i)); \
    (i) += 4;

Definition at line 22 of file bflt.c.

Function Documentation

bflt_init_hdr()

static bool bflt_init_hdr ( RzBfltObj *  bin )

static

Definition at line 26 of file bflt.c.

                                          {
    ut8 bhdr[BFLT_HDR_SIZE] = { 0 };
    st64 len = rz_buf_read_at(bin->b, 0, bhdr, BFLT_HDR_SIZE);
    if (len != BFLT_HDR_SIZE) {
        RZ_LOG_WARN("read bFLT hdr failed\n");
        return false;
    }
 
    if (strncmp((const char *)bhdr, "bFLT", 4)) {
        RZ_LOG_WARN("wrong magic number in bFLT file\n");
        return false;
    }
 
    size_t i = 4;
    bin->hdr.rev = READ(bhdr, i);
    bin->hdr.entry = READ(bhdr, i);
    bin->hdr.data_start = READ(bhdr, i);
    bin->hdr.data_end = READ(bhdr, i);
    bin->hdr.bss_end = READ(bhdr, i);
    bin->hdr.stack_size = READ(bhdr, i);
    bin->hdr.reloc_start = READ(bhdr, i);
    bin->hdr.reloc_count = READ(bhdr, i);
    bin->hdr.flags = READ(bhdr, i);
    bin->hdr.build_date = READ(bhdr, i);
 
    if (bin->hdr.rev != FLAT_VERSION) {
        RZ_LOG_WARN("only bFLT v4 is supported! This file has version %" PFMT32u "\n", bin->hdr.rev);
        return false;
    }
    if (bin->hdr.flags & FLAT_FLAG_GZIP || bin->hdr.flags & FLAT_FLAG_GZDATA) {
        RZ_LOG_WARN("this bFLT file is compressed. This is not (yet) supported.\n");
    }
    return true;
}

References BFLT_HDR_SIZE, FLAT_FLAG_GZDATA, FLAT_FLAG_GZIP, FLAT_VERSION, i, len, PFMT32u, READ, rz_buf_read_at(), RZ_LOG_WARN, and st64.

Referenced by rz_bflt_init().

bflt_load_relocs()

static void bflt_load_relocs ( RzBfltObj *  bin )

static

Definition at line 69 of file bflt.c.

                                             {
    bool big_endian = bflt_reloc_big_endian(bin);
 
    // got is a single table of 32bit values at the beginning of data
    // to be rebased in-place, and terminated by -1
    if (bin->hdr.flags & FLAT_FLAG_GOTPIC) {
        for (ut64 offset = 0;; offset += 4) {
            ut32 paddr = bin->hdr.data_start + offset;
            if (paddr + 4 > bin->size || paddr + 4 < paddr) {
                break;
            }
            ut32 value;
            if (!rz_buf_read_ble32_at(bin->b, paddr, &value, big_endian)) {
                break;
            }
            if (value == 0xffffffff) {
                break;
            }
            RzBfltReloc *reloc = rz_vector_push(&bin->got_relocs, NULL);
            if (!reloc) {
                break;
            }
            reloc->reloc_paddr = paddr;
            reloc->value_orig = value ? value + BFLT_HDR_SIZE : 0; // uClinux kernel leaves 0 relocs alone
        }
    }
 
    // addresses of other places to rebase are indirectly given in the reloc table
    for (ut32 i = 0; i < bin->hdr.reloc_count; i++) {
        ut32 table_paddr = bin->hdr.reloc_start + i * 4;
        if (table_paddr + 4 > bin->size || table_paddr + 4 < bin->hdr.reloc_start) {
            break;
        }
        ut32 reloc_paddr;
        if (!rz_buf_read_be32_at(bin->b, table_paddr, &reloc_paddr)) {
            break;
        }
        reloc_paddr += BFLT_HDR_SIZE;
        if (reloc_paddr + 4 < reloc_paddr || reloc_paddr > bin->size) {
            continue;
        }
        ut32 value;
        if (!rz_buf_read_ble32_at(bin->b, reloc_paddr, &value, big_endian)) {
            continue;
        }
        RzBfltReloc *reloc = rz_vector_push(&bin->got_relocs, NULL);
        if (!reloc) {
            break;
        }
        reloc->reloc_paddr = reloc_paddr;
        reloc->value_orig = value + BFLT_HDR_SIZE;
    }
}

References BFLT_HDR_SIZE, bflt_reloc_big_endian(), FLAT_FLAG_GOTPIC, i, NULL, rz_bflt_reloc_t::reloc_paddr, rz_buf_read_be32_at, rz_vector_push(), ut64(), value, and rz_bflt_reloc_t::value_orig.

Referenced by rz_bflt_init().

bflt_patch_relocs()

static void bflt_patch_relocs ( RzBfltObj *  bin )

static

Definition at line 137 of file bflt.c.

                                              {
    bin->buf_patched = rz_buf_new_sparse_overlay(bin->b, RZ_BUF_SPARSE_WRITE_MODE_SPARSE);
    if (!bin->buf_patched) {
        return;
    }
    patch_relocs_in(bin, &bin->got_relocs);
    patch_relocs_in(bin, &bin->relocs);
    rz_buf_sparse_set_write_mode(bin->buf_patched, RZ_BUF_SPARSE_WRITE_MODE_THROUGH);
}

References patch_relocs_in(), rz_buf_new_sparse_overlay(), rz_buf_sparse_set_write_mode(), RZ_BUF_SPARSE_WRITE_MODE_SPARSE, and RZ_BUF_SPARSE_WRITE_MODE_THROUGH.

Referenced by rz_bflt_init().

bflt_reloc_big_endian()

static bool bflt_reloc_big_endian ( RzBfltObj *  bin )

static

Definition at line 61 of file bflt.c.

                                                  {
    // if bin->hdr.flags & FLAT_FLAG_GOTPIC, then all relocs
    // are already in target order, otherwise they are always be
    return (bin->hdr.flags & FLAT_FLAG_GOTPIC)
        ? bin->big_endian
        : true;
}

References FLAT_FLAG_GOTPIC.

Referenced by bflt_load_relocs().

patch_relocs_in()

static void patch_relocs_in ( RzBfltObj *  bin, RzVector *  relocs  )

static

Definition at line 123 of file bflt.c.

                                                                {
    RzBfltReloc *reloc;
    rz_vector_foreach(relocs, reloc) {
        if (!reloc->value_orig) {
            // 0 relocs are not patched (this is some workaround for null pointers in the uClinux kernel)
            continue;
        }
        rz_buf_write_ble32_at(bin->buf_patched,
            reloc->reloc_paddr,
            rz_bflt_paddr_to_vaddr(bin, reloc->value_orig),
            bin->big_endian);
    }
}

References rz_bflt_reloc_t::reloc_paddr, relocs(), rz_bflt_paddr_to_vaddr(), rz_vector_foreach, and rz_bflt_reloc_t::value_orig.

Referenced by bflt_patch_relocs().

rz_bflt_free()

void rz_bflt_free

(

RzBfltObj *

obj

)

Definition at line 173 of file bflt.c.

                                  {
    if (obj) {
        rz_buf_free(obj->b);
        rz_buf_free(obj->buf_patched);
        rz_vector_fini(&obj->relocs);
        rz_vector_fini(&obj->got_relocs);
        RZ_FREE(obj);
    }
}

References rz_bflt_obj_t::b, rz_bflt_obj_t::buf_patched, rz_bflt_obj_t::got_relocs, rz_bflt_obj_t::relocs, rz_buf_free(), RZ_FREE, and rz_vector_fini().

Referenced by destroy(), and rz_bflt_new_buf().

rz_bflt_get_data_base()

ut64 rz_bflt_get_data_base

(

RzBfltObj *

bin

)

Address to map data+bss segment to.

Definition at line 198 of file bflt.c.

                                           {
    ut64 r = bin->baddr + bin->hdr.data_start + MAX_SHARED_LIBS * sizeof(ut32);
    return r + rz_num_align_delta(r, FLAT_DATA_ALIGN);
}

References FLAT_DATA_ALIGN, MAX_SHARED_LIBS, r, rz_num_align_delta(), and ut64().

Referenced by maps(), rz_bflt_paddr_to_vaddr(), and sections().

rz_bflt_get_data_vsize()

ut64 rz_bflt_get_data_vsize

(

RzBfltObj *

bin

)

Total size of data+bss.

Definition at line 204 of file bflt.c.

                                            {
    return RZ_MAX(bin->hdr.data_end, bin->hdr.bss_end) - bin->hdr.data_start;
}

References RZ_MAX.

Referenced by maps(), and sections().

rz_bflt_get_entry()

RzBinAddr* rz_bflt_get_entry

(

RzBfltObj *

bin

)

Definition at line 183 of file bflt.c.

                                             {
    RzBinAddr *addr = RZ_NEW0(RzBinAddr);
    if (addr && bin) {
        addr->paddr = bin->hdr.entry;
        addr->vaddr = rz_bflt_get_text_base(bin) + bin->hdr.entry;
    }
    return addr;
}

References addr, rz_bflt_get_text_base(), and RZ_NEW0.

Referenced by entries().

rz_bflt_get_text_base()

ut64 rz_bflt_get_text_base

(

RzBfltObj *

bin

)

Address to map text segment to.

Definition at line 193 of file bflt.c.

                                           {
    return bin->baddr;
}

Referenced by maps(), rz_bflt_get_entry(), and sections().

rz_bflt_init()

static bool rz_bflt_init ( RzBfltObj *  obj, RzBuffer *  buf, ut64  baddr, bool  big_endian, bool  patch_relocs  )

static

Definition at line 147 of file bflt.c.

                                                                                                        {
    obj->b = rz_buf_ref(buf);
    obj->size = rz_buf_size(buf);
    obj->big_endian = big_endian;
    rz_vector_init(&obj->relocs, sizeof(RzBfltReloc), NULL, NULL);
    rz_vector_init(&obj->got_relocs, sizeof(RzBfltReloc), NULL, NULL);
    obj->baddr = baddr == UT64_MAX ? 0 : baddr;
    if (!bflt_init_hdr(obj)) {
        return false;
    }
    bflt_load_relocs(obj);
    if (patch_relocs) {
        bflt_patch_relocs(obj);
    }
    return true;
}

References rz_bflt_obj_t::b, rz_bflt_obj_t::baddr, baddr(), bflt_init_hdr(), bflt_load_relocs(), bflt_patch_relocs(), rz_bflt_obj_t::big_endian, rz_bflt_obj_t::got_relocs, NULL, patch_relocs(), rz_bflt_obj_t::relocs, rz_buf_ref(), rz_buf_size(), rz_vector_init(), rz_bflt_obj_t::size, and UT64_MAX.

Referenced by rz_bflt_new_buf().

rz_bflt_new_buf()

RzBfltObj* rz_bflt_new_buf	(	RzBuffer *	buf,
		ut64	baddr,
		bool	big_endian,
		bool	patch_relocs
	)

Definition at line 164 of file bflt.c.

                                                                                          {
    RzBfltObj *bin = RZ_NEW0(RzBfltObj);
    if (bin && rz_bflt_init(bin, buf, baddr, big_endian, patch_relocs)) {
        return bin;
    }
    rz_bflt_free(bin);
    return NULL;
}

References baddr(), NULL, patch_relocs(), rz_bflt_free(), rz_bflt_init(), and RZ_NEW0.

Referenced by load_buffer().

rz_bflt_paddr_to_vaddr()

ut64 rz_bflt_paddr_to_vaddr	(	RzBfltObj *	bin,
		ut32	paddr
	)

Definition at line 208 of file bflt.c.

                                                        {
    if (paddr >= bin->hdr.data_start) {
        return rz_bflt_get_data_base(bin) + paddr - bin->hdr.data_start;
    }
    return bin->baddr + paddr;
}

References rz_bflt_get_data_base().

Referenced by convert_relocs(), and patch_relocs_in().