/*

  *  Copyright (C) 2007-2009 Sourcefire, Inc.

  *

  *  Authors: Tomasz Kojm

  *
  *  This program is free software; you can redistribute it and/or modify

  *  it under the terms of the GNU General Public License version 2 as
  *  published by the Free Software Foundation.

  *
  *  This program is distributed in the hope that it will be useful,
  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  *  GNU General Public License for more details.
  *
  *  You should have received a copy of the GNU General Public License
  *  along with this program; if not, write to the Free Software

  *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
  *  MA 02110-1301, USA.

  */
 

 #if HAVE_CONFIG_H
 #include "clamav-config.h"
 #endif
 

 #include <string.h>

 #include <ctype.h>
 #include <sys/types.h>
 #include <sys/stat.h>

 #ifdef	HAVE_UNISTD_H

 #include <unistd.h>

 #endif

 
 #include "clamav.h"
 #include "others.h"

 #include "matcher-ac.h"
 #include "matcher-bm.h"
 #include "md5.h"

 #include "filetypes.h"

 #include "matcher.h"

 #include "pe.h"

 #include "elf.h"
 #include "execs.h"

 #include "special.h"

 #include "str.h"

 #include "cltypes.h"

 #include "default.h"

 #include "macho.h"

 int cli_scanbuff(const unsigned char *buffer, uint32_t length, uint32_t offset, cli_ctx *ctx, cli_file_t ftype, struct cli_ac_data **acdata)

 {

 	int ret = CL_CLEAN;
 	unsigned int i;

 	struct cli_ac_data mdata;

 	struct cli_matcher *groot, *troot = NULL;

 	const char **virname=ctx->virname;
 	const struct cl_engine *engine=ctx->engine;

     if(!engine) {
 	cli_errmsg("cli_scanbuff: engine == NULL\n");
 	return CL_ENULLARG;
     }
 
     groot = engine->root[0]; /* generic signatures */
 
     if(ftype) {

 	for(i = 1; i < CLI_MTARGETS; i++) {
 	    if(cli_mtargets[i].target == ftype) {

 		troot = engine->root[i];

 		break;
 	    }
 	}
     }
 
     if(troot) {
 

 	if(!acdata && (ret = cli_ac_initdata(&mdata, troot->ac_partsigs, troot->ac_lsigs, troot->ac_reloff_num, CLI_DEFAULT_AC_TRACKLEN)))

 	    return ret;

 	if(troot->ac_only || (ret = cli_bm_scanbuff(buffer, length, virname, troot, offset, -1, NULL)) != CL_VIRUS)

 	    ret = cli_ac_scanbuff(buffer, length, virname, NULL, NULL, troot, acdata ? (acdata[0]) : (&mdata), offset, ftype, NULL, AC_SCAN_VIR, NULL);

 	if(!acdata)
 	    cli_ac_freedata(&mdata);

 
 	if(ret == CL_VIRUS)
 	    return ret;
     }
 

     if(!acdata && (ret = cli_ac_initdata(&mdata, groot->ac_partsigs, groot->ac_lsigs, groot->ac_reloff_num, CLI_DEFAULT_AC_TRACKLEN)))

 	return ret;

     if(groot->ac_only || (ret = cli_bm_scanbuff(buffer, length, virname, groot, offset, -1, NULL)) != CL_VIRUS)

 	ret = cli_ac_scanbuff(buffer, length, virname, NULL, NULL, groot, acdata ? (acdata[1]) : (&mdata), offset, ftype, NULL, AC_SCAN_VIR, NULL);

     if(!acdata)
 	cli_ac_freedata(&mdata);

 
     return ret;

 }
 

 /*
  * offdata[0]: type
  * offdata[1]: offset value
  * offdata[2]: max shift
  * offdata[3]: section number
  */
 int cli_caloff(const char *offstr, struct cli_target_info *info, int fd, unsigned int target, uint32_t *offdata, uint32_t *offset_min, uint32_t *offset_max)

 {

 	int (*einfo)(int, struct cli_exe_info *) = NULL;

 	char offcpy[65];

 	unsigned int n, val;

 	char *pt;
 	off_t pos;
 	struct stat sb;

     if(!info) { /* decode offset string */
 	if(!offstr) {
 	    cli_errmsg("cli_caloff: offstr == NULL\n");
 	    return CL_ENULLARG;
 	}

 	if(!strcmp(offstr, "*")) {
 	    offdata[0] = *offset_max = *offset_min = CLI_OFF_ANY;
 	    return CL_SUCCESS;
 	}

 	if(strlen(offstr) > 64) {
 	    cli_errmsg("cli_caloff: Offset string too long\n");
 	    return CL_EMALFDB;
 	}
 	strcpy(offcpy, offstr);

 	if((pt = strchr(offcpy, ','))) {
 	    if(!cli_isnumber(pt + 1)) {
 		cli_errmsg("cli_caloff: Invalid offset shift value\n");
 		return CL_EMALFDB;
 	    }
 	    offdata[2] = atoi(pt + 1);
 	    *pt = 0;
 	} else {
 	    offdata[2] = 0;
 	}

 	*offset_max = *offset_min = CLI_OFF_NONE;

 	if(!strncmp(offcpy, "EP+", 3) || !strncmp(offcpy, "EP-", 3)) {
 	    if(offcpy[2] == '+')
 		offdata[0] = CLI_OFF_EP_PLUS;
 	    else
 		offdata[0] = CLI_OFF_EP_MINUS;

 	    if(!cli_isnumber(&offcpy[3])) {
 		cli_errmsg("cli_caloff: Invalid offset value\n");
 		return CL_EMALFDB;
 	    }
 	    offdata[1] = atoi(&offcpy[3]);
 
 	} else if(offcpy[0] == 'S') {
 	    if(!strncmp(offstr, "SL+", 3)) {
 		offdata[0] = CLI_OFF_SL_PLUS;
 		if(!cli_isnumber(&offcpy[3])) {
 		    cli_errmsg("cli_caloff: Invalid offset value\n");
 		    return CL_EMALFDB;

 		}

 		offdata[1] = atoi(&offcpy[3]);
 
 	    } else if(sscanf(offcpy, "S%u+%u", &n, &val) == 2) {
 		offdata[0] = CLI_OFF_SX_PLUS;
 		offdata[1] = val;
 		offdata[3] = n;
 	    } else {
 		cli_errmsg("cli_caloff: Invalid offset string\n");
 		return CL_EMALFDB;
 	    }

 	} else if(!strncmp(offcpy, "EOF-", 4)) {
 	    offdata[0] = CLI_OFF_EOF_MINUS;
 	    if(!cli_isnumber(&offcpy[4])) {
 		cli_errmsg("cli_caloff: Invalid offset value\n");
 		return CL_EMALFDB;

 	    }

 	    offdata[1] = atoi(&offcpy[4]);
 	} else {
 	    offdata[0] = CLI_OFF_ABSOLUTE;
 	    if(!cli_isnumber(offcpy)) {
 		cli_errmsg("cli_caloff: Invalid offset value\n");
 		return CL_EMALFDB;
 	    }
 	    *offset_min = offdata[1] = atoi(offcpy);
 	    *offset_max = *offset_min + offdata[2];

 	}

 	if(offdata[0] != CLI_OFF_ANY && offdata[0] != CLI_OFF_ABSOLUTE && offdata[0] != CLI_OFF_EOF_MINUS) {
 	    if(target != 1 && target != 6 && target != 9) {
 		cli_errmsg("cli_caloff: Invalid offset type for target %u\n", target);
 		return CL_EMALFDB;
 	    }
 	}

     } else {
 	/* calculate relative offsets */
 	if(info->status == -1) {

 	    *offset_min = CLI_OFF_NONE;
 	    if(offset_max)
 		*offset_max = CLI_OFF_NONE;

 	    return CL_SUCCESS;
 	}

 	if((offdata[0] == CLI_OFF_EOF_MINUS)) {
 	    if(!info->fsize) {
 		if(fstat(fd, &sb) == -1) {
 		    cli_errmsg("cli_caloff: fstat(%d) failed\n", fd);
 		    return CL_ESTAT;
 		}
 		info->fsize = sb.st_size;

 	    }
 

 	} else if(!info->status) {
 	    if(target == 1)
 		einfo = cli_peheader;
 	    else if(target == 6)
 		einfo = cli_elfheader;
 	    else if(target == 9)
 		einfo = cli_machoheader;

 	    if(!einfo) {
 		cli_errmsg("cli_caloff: Invalid offset/filetype\n");
 		return CL_EMALFDB;

 	    }
 

 	    if((pos = lseek(fd, 0, SEEK_CUR)) == -1) {
 		cli_errmsg("cli_caloff: lseek(%d) failed\n", fd);
 		return CL_ESEEK;

 	    }
 

 	    lseek(fd, 0, SEEK_SET);
 	    if(einfo(fd, &info->exeinfo)) {
 		/* einfo *may* fail */
 		lseek(fd, pos, SEEK_SET);
 		info->status = -1;

 		*offset_min = CLI_OFF_NONE;
 		if(offset_max)
 		    *offset_max = CLI_OFF_NONE;

 		return CL_SUCCESS;
 	    }
 	    lseek(fd, pos, SEEK_SET);
 	    info->status = 1;

 	}
 

 	switch(offdata[0]) {
 	    case CLI_OFF_EOF_MINUS:
 		*offset_min = info->fsize - offdata[1];
 		break;

 	    case CLI_OFF_EP_PLUS:
 		*offset_min = info->exeinfo.ep + offdata[1];
 		break;

 	    case CLI_OFF_EP_MINUS:
 		*offset_min = info->exeinfo.ep - offdata[1];
 		break;
 
 	    case CLI_OFF_SL_PLUS:
 		*offset_min = info->exeinfo.section[info->exeinfo.nsections - 1].raw + offdata[1];
 		break;
 
 	    case CLI_OFF_SX_PLUS:
 		if(offdata[3] >= info->exeinfo.nsections)

 		    *offset_min = CLI_OFF_NONE;

 		else
 		    *offset_min = info->exeinfo.section[offdata[3]].raw + offdata[1];
 		break;
 
 	    default:
 		cli_errmsg("cli_caloff: Not a relative offset (type: %u)\n", offdata[0]);
 		return CL_EARG;

 	}

 	if(offset_max && *offset_min != CLI_OFF_NONE)

 	    *offset_max = *offset_min + offdata[2];

     }
 

     return CL_SUCCESS;

 }
 

 int cli_checkfp(int fd, cli_ctx *ctx)

 {

 	unsigned char *digest;

 	const char *virname;

 	off_t pos;

     if((pos = lseek(fd, 0, SEEK_CUR)) == -1) {
 	cli_errmsg("cli_checkfp(): lseek() failed\n");
 	return 0;
     }
 
     lseek(fd, 0, SEEK_SET);
 
     if(ctx->engine->md5_fp) {

 	if(!(digest = cli_md5digest(fd))) {
 	    cli_errmsg("cli_checkfp(): Can't generate MD5 checksum\n");

 	    lseek(fd, pos, SEEK_SET);

 	    return 0;
 	}
 

 	if(cli_bm_scanbuff(digest, 16, &virname, ctx->engine->md5_fp, 0, -1, NULL) == CL_VIRUS) {

 	    cli_dbgmsg("cli_checkfp(): Found false positive detection (fp sig: %s)\n", virname);

 	    free(digest);

 	    lseek(fd, pos, SEEK_SET);

 	    return 1;

 	}
 	free(digest);
     }
 

     lseek(fd, pos, SEEK_SET);

     return 0;
 }
 

 int cli_scandesc(int desc, cli_ctx *ctx, cli_file_t ftype, uint8_t ftonly, struct cli_matched_type **ftoffset, unsigned int acmode)

 {

         unsigned char *buffer, *buff, *endbl, *upt;

 	int ret = CL_CLEAN, type = CL_CLEAN, bytes;

 	unsigned int i, evalcnt, bm_offmode = 0;

 	uint32_t buffersize, length, maxpatlen, shift = 0, offset = 0;

 	uint64_t evalids;

 	struct cli_ac_data gdata, tdata;

 	struct cli_bm_off toff;

 	cli_md5_ctx md5ctx;

 	unsigned char digest[16];

 	struct cli_matcher *groot = NULL, *troot = NULL;

 	struct stat sb;

     if(!ctx->engine) {

 	cli_errmsg("cli_scandesc: engine == NULL\n");

 	return CL_ENULLARG;

     }
 

     if(!ftonly)
 	groot = ctx->engine->root[0]; /* generic signatures */

 
     if(ftype) {

 	for(i = 1; i < CLI_MTARGETS; i++) {
 	    if(cli_mtargets[i].target == ftype) {

 		troot = ctx->engine->root[i];

 		break;
 	    }
 	}
     }
 

     if(ftonly) {
 	if(!troot)
 	    return CL_CLEAN;
 
 	maxpatlen = troot->maxpatlen;
     } else {
 	if(troot)
 	    maxpatlen = MAX(troot->maxpatlen, groot->maxpatlen);
 	else
 	    maxpatlen = groot->maxpatlen;
     }

     /* prepare the buffer */

     buffersize = maxpatlen + SCANBUFF;

     if(!(buffer = (unsigned char *) cli_calloc(buffersize, sizeof(unsigned char)))) {

 	cli_dbgmsg("cli_scandesc(): unable to cli_calloc(%u)\n", buffersize);

 	return CL_EMEM;
     }

     if(!ftonly)

 	if((ret = cli_ac_initdata(&gdata, groot->ac_partsigs, groot->ac_lsigs, groot->ac_reloff_num, CLI_DEFAULT_AC_TRACKLEN)) || (ret = cli_ac_caloff(groot, &gdata, desc)))

 	    return ret;

     if(troot) {

 	if((ret = cli_ac_initdata(&tdata, troot->ac_partsigs, troot->ac_lsigs, troot->ac_reloff_num, CLI_DEFAULT_AC_TRACKLEN)) || (ret = cli_ac_caloff(troot, &tdata, desc))) {

 	    if(!ftonly)
 		cli_ac_freedata(&gdata);

 	    return ret;

 	}

 	if(troot->bm_offmode) {
 	    if(fstat(desc, &sb) != -1) {
 		if(sb.st_size >= CLI_DEFAULT_BM_OFFMODE_FSIZE) {
 		    if((ret = cli_bm_initoff(troot, &toff, desc))) {
 			if(!ftonly)
 			    cli_ac_freedata(&gdata);
 			cli_ac_freedata(&tdata);
 			return ret;
 		    }
 		    bm_offmode = 1;
 		}
 	    }

 	}

     }
 

     if(!ftonly && ctx->engine->md5_hdb)

 	cli_md5_init(&md5ctx);

     buff = buffer;

     buff += maxpatlen; /* pointer to read data block */
     endbl = buff + SCANBUFF - maxpatlen; /* pointer to the last block

 					  * length of maxpatlen
 					  */

     upt = buff;

     while((bytes = cli_readn(desc, buff + shift, SCANBUFF - shift)) > 0) {

 	if(ctx->scanned)
 	    *ctx->scanned += bytes / CL_COUNT_PRECISION;

 	length = shift + bytes;

 	if(upt == buffer)

 	    length += maxpatlen;

 	if(troot) {

 	    if(troot->ac_only || (ret = cli_bm_scanbuff(upt, length, ctx->virname, troot, offset, desc, bm_offmode ? &toff : NULL)) != CL_VIRUS)

 		ret = cli_ac_scanbuff(upt, length, ctx->virname, NULL, NULL, troot, &tdata, offset, ftype, ftoffset, acmode, NULL);

 
 	    if(ret == CL_VIRUS) {

 		free(buffer);

 		if(!ftonly)
 		    cli_ac_freedata(&gdata);

 		cli_ac_freedata(&tdata);

 		if(bm_offmode)

 		    cli_bm_freeoff(&toff, troot);

 		if(cli_checkfp(desc, ctx))

 		    return CL_CLEAN;
 		else
 		    return CL_VIRUS;
 	    }
 	}

 	if(!ftonly) {

 	    if(groot->ac_only || (ret = cli_bm_scanbuff(upt, length, ctx->virname, groot, offset, desc, NULL)) != CL_VIRUS)

 		ret = cli_ac_scanbuff(upt, length, ctx->virname, NULL, NULL, groot, &gdata, offset, ftype, ftoffset, acmode, NULL);

 	    if(ret == CL_VIRUS) {
 		free(buffer);
 		cli_ac_freedata(&gdata);

 		if(troot) {

 		    cli_ac_freedata(&tdata);

 		    if(bm_offmode)

 			cli_bm_freeoff(&toff, troot);

 		}

 		if(cli_checkfp(desc, ctx))

 		    return CL_CLEAN;
 		else
 		    return CL_VIRUS;

 	    } else if((acmode & AC_SCAN_FT) && ret >= CL_TYPENO) {

 		if(ret > type)
 		    type = ret;
 	    }

 	    if(ctx->engine->md5_hdb)

 		cli_md5_update(&md5ctx, buff + shift, bytes);

 	}

 
 	if(bytes + shift == SCANBUFF) {

 	    memmove(buffer, endbl, maxpatlen);

 	    offset += SCANBUFF;

 	    if(upt == buff) {
 		upt = buffer;

 		offset -= maxpatlen;

 	    }

 
 	    shift = 0;
 
 	} else {
 	    shift += bytes;

 	}

     }

     free(buffer);

 
     if(troot) {
 	for(i = 0; i < troot->ac_lsigs; i++) {
 	    evalcnt = 0;

 	    evalids = 0;
 	    if(cli_ac_chklsig(troot->ac_lsigtable[i]->logic, troot->ac_lsigtable[i]->logic + strlen(troot->ac_lsigtable[i]->logic), tdata.lsigcnt[i], &evalcnt, &evalids, 0) == 1) {

 		if (!troot->ac_lsigtable[i]->bc) {
 		    if(ctx->virname)
 			*ctx->virname = troot->ac_lsigtable[i]->virname;
 		    ret = CL_VIRUS;
 		    break;
 		}
 		if (cli_bytecode_runlsig(&ctx->engine->bcs, troot->ac_lsigtable[i]->bc, ctx->virname, tdata.lsigcnt[i], desc) == CL_VIRUS) {
 		    ret = CL_VIRUS;
 		    break;
 		}

 	    }
 	}

 	cli_ac_freedata(&tdata);

 	if(bm_offmode)

 	    cli_bm_freeoff(&toff, troot);

     }
 
     if(groot) {
 	if(ret != CL_VIRUS) for(i = 0; i < groot->ac_lsigs; i++) {
 	    evalcnt = 0;

 	    evalids = 0;
 	    if(cli_ac_chklsig(groot->ac_lsigtable[i]->logic, groot->ac_lsigtable[i]->logic + strlen(groot->ac_lsigtable[i]->logic), gdata.lsigcnt[i], &evalcnt, &evalids, 0) == 1) {

 		if (!groot->ac_lsigtable[i]->bc) {
 		    if(ctx->virname)
 			*ctx->virname = groot->ac_lsigtable[i]->virname;
 		    ret = CL_VIRUS;
 		    break;
 		}
 		if (cli_bytecode_runlsig(&ctx->engine->bcs, groot->ac_lsigtable[i]->bc, ctx->virname, gdata.lsigcnt[i], desc) == CL_VIRUS) {
 		    ret = CL_VIRUS;
 		    break;
 		}

 	    }
 	}
 	cli_ac_freedata(&gdata);
     }
 

     if(ret == CL_VIRUS) {
 	lseek(desc, 0, SEEK_SET);

 	if(cli_checkfp(desc, ctx))

 	    return CL_CLEAN;
 	else
 	    return CL_VIRUS;
     }

     if(!ftonly && ctx->engine->md5_hdb) {

 	cli_md5_final(digest, &md5ctx);

 	if(cli_bm_scanbuff(digest, 16, ctx->virname, ctx->engine->md5_hdb, 0, -1, NULL) == CL_VIRUS && (cli_bm_scanbuff(digest, 16, NULL, ctx->engine->md5_fp, 0, -1, NULL) != CL_VIRUS))

 	    return CL_VIRUS;

     }
 

     return (acmode & AC_SCAN_FT) ? type : CL_CLEAN;

 }