coff.c

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// SPDX-FileCopyrightText: 2008-2019 pancake <pancake@nopcode.org>
// SPDX-FileCopyrightText: 2008-2019 inisider <inisider@gmail.com>
// SPDX-License-Identifier: LGPL-3.0-only
 
#include <rz_util.h>
 
#include "coff.h"
 
RZ_API bool rz_coff_supported_arch(const ut8 *buf) {
    ut16 arch = rz_read_le16(buf);
    switch (arch) {
    case COFF_FILE_MACHINE_MIPS16:
    case COFF_FILE_MACHINE_MIPSFPU:
    case COFF_FILE_MACHINE_MIPSFPU16:
    case COFF_FILE_MACHINE_AMD64:
    case COFF_FILE_MACHINE_I386:
    case COFF_FILE_MACHINE_H8300:
    case COFF_FILE_TI_COFF:
    case COFF_FILE_MACHINE_R4000:
    case COFF_FILE_MACHINE_AMD29KBE:
    case COFF_FILE_MACHINE_AMD29KLE:
    case COFF_FILE_MACHINE_SH3:
    case COFF_FILE_MACHINE_SH3DSP:
    case COFF_FILE_MACHINE_SH4:
    case COFF_FILE_MACHINE_SH5:
    case COFF_FILE_MACHINE_THUMB:
    case COFF_FILE_MACHINE_ARM:
    case COFF_FILE_MACHINE_ARM64:
    case COFF_FILE_MACHINE_ARMNT:
        return true;
    default:
        return false;
    }
}
 
RZ_API ut64 rz_coff_perms_from_section_flags(ut32 flags) {
    ut32 r = 0;
    if (flags & COFF_SCN_MEM_READ) {
        r |= RZ_PERM_R;
    }
    if (flags & COFF_SCN_MEM_WRITE) {
        r |= RZ_PERM_W;
    }
    if (flags & COFF_SCN_MEM_EXECUTE) {
        r |= RZ_PERM_X;
    }
    return r;
}
 
RZ_API char *rz_coff_symbol_name(struct rz_bin_coff_obj *obj, void *ptr) {
    char n[256] = { 0 };
    int len = 0, offset = 0;
    union {
        char name[8];
        struct {
            ut32 zero;
            ut32 offset;
        };
    } *p = ptr;
    if (!ptr) {
        return strdup("");
    }
    if (p->zero) {
        return rz_str_ndup(p->name, 8);
    }
    offset = obj->hdr.f_symptr + obj->hdr.f_nsyms * sizeof(struct coff_symbol) + p->offset;
    if (offset > obj->size) {
        return strdup("");
    }
    len = rz_buf_read_at(obj->b, offset, (ut8 *)n, sizeof(n));
    if (len < 1) {
        return strdup("");
    }
    /* ensure null terminated string */
    n[sizeof(n) - 1] = 0;
    return strdup(n);
}
 
static int rz_coff_rebase_sym(struct rz_bin_coff_obj *obj, RzBinAddr *addr, struct coff_symbol *sym) {
    if (sym->n_scnum < 1 || sym->n_scnum > obj->hdr.f_nscns) {
        return 0;
    }
    addr->paddr = obj->scn_hdrs[sym->n_scnum - 1].s_scnptr + sym->n_value;
    return 1;
}
 
/* Try to get a valid entrypoint using the methods outlined in
 * http://ftp.gnu.org/old-gnu/Manuals/ld-2.9.1/html_mono/ld.html#SEC24 */
RZ_API RzBinAddr *rz_coff_get_entry(struct rz_bin_coff_obj *obj) {
    RzBinAddr *addr = RZ_NEW0(RzBinAddr);
    int i;
    if (!addr) {
        return NULL;
    }
    /* Simplest case, the header provides the entrypoint address */
    if (obj->hdr.f_opthdr) {
        addr->paddr = obj->opt_hdr.entry;
        return addr;
    }
    /* No help from the header eh? Use the address of the symbols '_start'
     * or 'main' if present */
    if (obj->symbols) {
        for (i = 0; i < obj->hdr.f_nsyms; i++) {
            if ((!strcmp(obj->symbols[i].n_name, "_start") ||
                    !strcmp(obj->symbols[i].n_name, "start")) &&
                rz_coff_rebase_sym(obj, addr, &obj->symbols[i])) {
                return addr;
            }
        }
        for (i = 0; i < obj->hdr.f_nsyms; i++) {
            if ((!strcmp(obj->symbols[i].n_name, "_main") ||
                    !strcmp(obj->symbols[i].n_name, "main")) &&
                rz_coff_rebase_sym(obj, addr, &obj->symbols[i])) {
                return addr;
            }
        }
    }
#if 0
    /* Still clueless ? Let's just use the address of .text */
    if (obj->scn_hdrs) {
        for (i = 0; i < obj->hdr.f_nscns; i++) {
            // avoid doing string matching and use x bit from the section
            if (obj->scn_hdrs[i].s_flags & COFF_SCN_MEM_EXECUTE) {
                addr->paddr = obj->scn_hdrs[i].s_scnptr;
                return addr;
            }
        }
    }
#else
    free(addr);
    return NULL;
#endif
    return addr;
}
 
static bool rz_bin_coff_init_hdr(struct rz_bin_coff_obj *obj) {
    ut16 magic;
    if (!rz_buf_read_le16_at(obj->b, 0, &magic)) {
        return false;
    }
 
    switch (magic) {
    case COFF_FILE_MACHINE_H8300:
    case COFF_FILE_MACHINE_AMD29KBE:
        obj->endian = COFF_IS_BIG_ENDIAN;
        break;
    default:
        obj->endian = COFF_IS_LITTLE_ENDIAN;
    }
    int ret = 0;
    ret = rz_buf_fread_at(obj->b, 0, (ut8 *)&obj->hdr, obj->endian ? "2S3I2S" : "2s3i2s", 1);
    if (ret != sizeof(struct coff_hdr)) {
        return false;
    }
    if (obj->hdr.f_magic == COFF_FILE_TI_COFF) {
        ret = rz_buf_fread(obj->b, (ut8 *)&obj->target_id, obj->endian ? "S" : "s", 1);
        if (ret != sizeof(ut16)) {
            return false;
        }
    }
    return true;
}
 
static bool rz_bin_coff_init_opt_hdr(struct rz_bin_coff_obj *obj) {
    int ret;
    if (!obj->hdr.f_opthdr) {
        return false;
    }
    ret = rz_buf_fread_at(obj->b, sizeof(struct coff_hdr),
        (ut8 *)&obj->opt_hdr, obj->endian ? "2S6I" : "2s6i", 1);
    if (ret != sizeof(struct coff_opt_hdr)) {
        return false;
    }
    return true;
}
 
static bool rz_bin_coff_init_scn_hdr(struct rz_bin_coff_obj *obj) {
    int ret, size;
    ut64 offset = sizeof(struct coff_hdr) + (obj->hdr.f_opthdr ? sizeof(struct coff_opt_hdr) : 0);
    if (obj->hdr.f_magic == COFF_FILE_TI_COFF) {
        offset += 2;
    }
    size = obj->hdr.f_nscns * sizeof(struct coff_scn_hdr);
    if (offset > obj->size || offset + size > obj->size || size < 0) {
        return false;
    }
    obj->scn_hdrs = calloc(1, size + sizeof(struct coff_scn_hdr));
    if (!obj->scn_hdrs) {
        return false;
    }
    ret = rz_buf_fread_at(obj->b, offset, (ut8 *)obj->scn_hdrs, obj->endian ? "8c6I2S1I" : "8c6i2s1i", obj->hdr.f_nscns);
    if (ret != size) {
        RZ_FREE(obj->scn_hdrs);
        return false;
    }
    return true;
}
 
static bool rz_bin_coff_init_symtable(struct rz_bin_coff_obj *obj) {
    int ret, size;
    ut64 offset = obj->hdr.f_symptr;
    if (obj->hdr.f_nsyms >= 0xffff || !obj->hdr.f_nsyms) { // too much symbols, probably not allocatable
        return false;
    }
    size = obj->hdr.f_nsyms * sizeof(struct coff_symbol);
    if (size < 0 ||
        size > obj->size ||
        offset > obj->size ||
        offset + size > obj->size) {
        return false;
    }
    obj->symbols = calloc(1, size + sizeof(struct coff_symbol));
    if (!obj->symbols) {
        return false;
    }
    ret = rz_buf_fread_at(obj->b, offset, (ut8 *)obj->symbols, obj->endian ? "8c1I2S2c" : "8c1i2s2c", obj->hdr.f_nsyms);
    if (ret != size) {
        RZ_FREE(obj->symbols);
        return false;
    }
    return true;
}
 
static bool rz_bin_coff_init_scn_va(struct rz_bin_coff_obj *obj) {
    obj->scn_va = RZ_NEWS(ut64, obj->hdr.f_nscns);
    if (!obj->scn_va) {
        return false;
    }
    int i;
    ut64 va = 0;
    for (i = 0; i < obj->hdr.f_nscns; i++) {
        obj->scn_va[i] = va;
        va += obj->scn_hdrs[i].s_size ? obj->scn_hdrs[i].s_size : 16;
        va = RZ_ROUND(va, 16ULL);
    }
    return true;
}
 
static int rz_bin_coff_init(struct rz_bin_coff_obj *obj, RzBuffer *buf, bool verbose) {
    obj->b = rz_buf_ref(buf);
    obj->size = rz_buf_size(buf);
    obj->verbose = verbose;
    obj->sym_ht = ht_up_new0();
    obj->imp_ht = ht_up_new0();
    obj->imp_index = ht_uu_new0();
    if (!rz_bin_coff_init_hdr(obj)) {
        RZ_LOG_ERROR("failed to init hdr\n");
        return false;
    }
    rz_bin_coff_init_opt_hdr(obj);
    if (!rz_bin_coff_init_scn_hdr(obj)) {
        RZ_LOG_ERROR("failed to init section header\n");
        return false;
    }
    if (!rz_bin_coff_init_scn_va(obj)) {
        RZ_LOG_ERROR("failed to init section VA table\n");
        return false;
    }
    if (!rz_bin_coff_init_symtable(obj)) {
        RZ_LOG_ERROR("failed to init symtable\n");
        return false;
    }
    return true;
}
 
RZ_API void rz_bin_coff_free(struct rz_bin_coff_obj *obj) {
    ht_up_free(obj->sym_ht);
    ht_up_free(obj->imp_ht);
    ht_uu_free(obj->imp_index);
    free(obj->scn_va);
    free(obj->scn_hdrs);
    free(obj->symbols);
    rz_buf_free(obj->buf_patched);
    rz_buf_free(obj->b);
    free(obj);
}
 
RZ_API struct rz_bin_coff_obj *rz_bin_coff_new_buf(RzBuffer *buf, bool verbose) {
    struct rz_bin_coff_obj *bin = RZ_NEW0(struct rz_bin_coff_obj);
    rz_bin_coff_init(bin, buf, verbose);
    return bin;
}