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/****************************************************************/
/* mdso: midipix dso scavenger */
/* Copyright (C) 2015--2017 Z. Gilboa */
/* Released under GPLv2 and GPLv3; see COPYING.MDSO. */
/****************************************************************/
#include <stdio.h>
#include <stddef.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <mdso/mdso.h>
#include "mdso_object_impl.h"
#include "mdso_errinfo_impl.h"
#include "perk_consts.h"
#include "perk_structs.h"
static const unsigned char jmp_code_i386[16] = {
0xff,0x25,
0x0,0x0,0x0,0x0,
0x90,0x90,
0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0
};
static const unsigned char jmp_code_amd64[16] = {
0xff,0x24,0x25,
0x0,0x0,0x0,0x0,
0x90,
0x90,0x90,0x90,0x90,0x90,0x90,0x90,0x90
};
struct mdso_symfn_code {
unsigned char code[16];
};
struct mdso_symfn_object {
struct pe_raw_coff_object_hdr hdr;
struct pe_raw_sec_hdr sec[1];
struct mdso_symfn_code cod[1];
struct pe_raw_coff_reloc rel[1];
struct pe_raw_coff_symbol sym[7];
struct pe_raw_coff_strtbl cst;
};
int mdso_objgen_symfn(
const struct mdso_driver_ctx * dctx,
const char * sym,
struct mdso_object * vobj)
{
struct mdso_symfn_object * symfn;
struct pe_raw_coff_symbol * symrec;
const unsigned char * code;
void * addr;
unsigned char * mark;
unsigned char * mapsym;
struct pe_raw_aux_rec_section * aux;
size_t buflen;
uint32_t symlen;
uint32_t cstlen;
uint32_t objlen;
uint32_t aattr;
uint32_t sattr;
uint16_t oattr;
uint16_t machine;
uint16_t reltype;
uint32_t relrva;
uint32_t reloff;
uint32_t symoff;
uint32_t cstoff;
uint32_t codoff;
uint32_t datoff;
uint32_t uscore;
if ((buflen = strlen(sym)) > 1024*1024)
return MDSO_CUSTOM_ERROR(dctx,MDSO_ERR_INVALID_DATA);
symlen = (uint32_t)buflen;
cstlen = (3 * symlen) + 32;
objlen = sizeof(*symfn) + cstlen;
uscore = !(dctx->cctx->drvflags & MDSO_DRIVER_QUAD_PTR);
if (vobj->addr && (vobj->size < objlen))
return MDSO_BUFFER_ERROR(dctx);
if ((addr = vobj->addr)) {
(void)0;
} else {
vobj->size = objlen;
vobj->mapstrsnum = 1;
vobj->mapstrslen = 1 + uscore + symlen;
if (!vobj->name)
return 0;
else if (mdso_create_object(dctx,vobj) < 0)
return MDSO_NESTED_ERROR(dctx);
}
symfn = (struct mdso_symfn_object *)vobj->addr;
if (dctx->cctx->drvflags & MDSO_DRIVER_QUAD_PTR) {
code = jmp_code_amd64;
aattr = PE_IMAGE_SCN_ALIGN_16BYTES;
machine = PE_IMAGE_FILE_MACHINE_AMD64;
reltype = PE_IMAGE_REL_AMD64_ADDR32;
relrva = 3;
} else {
code = jmp_code_i386;
aattr = PE_IMAGE_SCN_ALIGN_4BYTES;
machine = PE_IMAGE_FILE_MACHINE_I386;
reltype = PE_IMAGE_REL_I386_DIR32;
relrva = 2;
}
sattr = aattr;
sattr |= PE_IMAGE_SCN_MEM_READ;
sattr |= PE_IMAGE_SCN_MEM_EXECUTE;
sattr |= PE_IMAGE_SCN_CNT_CODE;
oattr = PE_IMAGE_FILE_LINE_NUMS_STRIPPED;
reloff = offsetof(struct mdso_symfn_object,rel);
symoff = offsetof(struct mdso_symfn_object,sym);
codoff = offsetof(struct mdso_symfn_object,cod);
cstoff = offsetof(struct pe_raw_coff_strtbl,cst_data);
datoff = 0;
/* coff object header */
mdso_obj_write_short(symfn->hdr.cfh_machine,machine);
mdso_obj_write_short(symfn->hdr.cfh_num_of_sections,1);
mdso_obj_write_long(symfn->hdr.cfh_ptr_to_sym_tbl,symoff);
mdso_obj_write_long(symfn->hdr.cfh_num_of_syms,7);
mdso_obj_write_short(symfn->hdr.cfh_characteristics,oattr);
/* .text section header */
memcpy(symfn->sec[0].sh_name,".text",5);
mdso_obj_write_long(symfn->sec[0].sh_size_of_raw_data,16);
mdso_obj_write_long(symfn->sec[0].sh_ptr_to_raw_data,codoff);
mdso_obj_write_long(symfn->sec[0].sh_ptr_to_relocs,reloff);
mdso_obj_write_short(symfn->sec[0].sh_num_of_relocs,1);
mdso_obj_write_long(symfn->sec[0].sh_characteristics,sattr);
/* .text section content */
memcpy(symfn->cod,code,16);
/* .text relocation record */
mdso_obj_write_long(symfn->rel[0].rel_sym,6);
mdso_obj_write_long(symfn->rel[0].rel_rva,relrva);
mdso_obj_write_short(symfn->rel[0].rel_type,reltype);
/* coff string table */
mdso_obj_write_long(symfn->cst.cst_size,cstlen);
/* coff symbol table */
symrec = symfn->sym;
mark = symfn->cst.cst_data;
/* coff symbol: .file */
symrec[0].cs_storage_class[0] = PE_IMAGE_SYM_CLASS_FILE;
symrec[0].cs_num_of_aux_symbols[0] = 1;
mdso_obj_write_short(&symrec[0].cs_section_number[0],PE_IMAGE_SYM_DEBUG);
mdso_obj_write_long(&symrec[1].cs_name[4],cstoff+datoff);
memcpy(symrec[0].cs_name,".file",5);
memcpy(&mark[0],".",1);
memcpy(&mark[1],sym,symlen);
memcpy(&mark[1+symlen],"_symfn.s",8);
datoff += 10 + symlen;
mark += 10 + symlen;
symrec += 2;
/* coff symbol: .text */
symrec[0].cs_storage_class[0] = PE_IMAGE_SYM_CLASS_STATIC;
symrec[0].cs_num_of_aux_symbols[0] = 1;
mdso_obj_write_short(symrec[0].cs_section_number,1);
memcpy(symrec[0].cs_name,".text",5);
aux = (struct pe_raw_aux_rec_section *)&symrec[1];
mdso_obj_write_long(aux->aux_size,relrva+4);
mdso_obj_write_short(aux->aux_num_of_relocs,1);
datoff += 0;
mark += 0;
symrec += 2;
/* coff symbol: sym */
mapsym = mark;
symrec[0].cs_storage_class[0] = PE_IMAGE_SYM_CLASS_EXTERNAL;
symrec[0].cs_num_of_aux_symbols[0] = 1;
mdso_obj_write_short(symrec[0].cs_type,PE_IMAGE_SYM_DTYPE_FUNCTION<<8);
mdso_obj_write_short(symrec[0].cs_section_number,1);
mdso_obj_write_long(&symrec[0].cs_name[4],cstoff+datoff);
if (dctx->cctx->drvflags & MDSO_DRIVER_QUAD_PTR) {
memcpy(&mark[0],sym,symlen);
} else {
memcpy(&mark[1],sym,symlen);
mark[0] = '_';
datoff++;
mark++;
}
datoff += 1 + symlen;
mark += 1 + symlen;
symrec += 2;
/* archive symbol map */
if (vobj->mapstrs)
memcpy(vobj->mapstrs,mapsym,mark-mapsym);
/* coff symbol: __imp_sym */
symrec[0].cs_storage_class[0] = PE_IMAGE_SYM_CLASS_EXTERNAL;
symrec[0].cs_num_of_aux_symbols[0] = 0;
mdso_obj_write_short(symrec[0].cs_section_number,0);
mdso_obj_write_long(&symrec[0].cs_name[4],cstoff+datoff);
if (dctx->cctx->drvflags & MDSO_DRIVER_QUAD_PTR) {
memcpy(&mark[0],"__imp_",6);
memcpy(&mark[6],sym,symlen);
} else {
memcpy(&mark[0],"__imp_",6);
memcpy(&mark[7],sym,symlen);
mark[6] = '_';
datoff++;
mark++;
}
/* fs object unmap */
if (!addr)
munmap(vobj->addr,vobj->size);
/* tada */
return 0;
}
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