File: 7z_iface.c

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/*
 *  Copyright (C) 2011 Sourcefire, Inc.
 *
 *  Authors: aCaB
 *
 *  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 defined(_WIN32)
#include <WinSock2.h>
#include <Windows.h>
#endif

#include "clamav.h"
#include "7z_iface.h"
#include "lzma_iface.h"
#include "scanners.h"
#include "others.h"
#include "fmap.h"

#include "7z/7z.h"
#include "7z/7zAlloc.h"
#include "7z/7zFile.h"


static ISzAlloc allocImp = { __lzma_wrap_alloc, __lzma_wrap_free}, allocTempImp = { __lzma_wrap_alloc, __lzma_wrap_free};

static SRes FileInStream_fmap_Read(void *pp, void *buf, size_t *size) {
    CFileInStream *p = (CFileInStream *)pp;
    int read_sz;

    if (*size == 0)
	return 0;

    read_sz = fmap_readn(p->file.fmap, buf, p->s.curpos, *size);
    if(read_sz < 0) {
	*size = 0;
	return SZ_ERROR_READ;
    }

    p->s.curpos += read_sz;

    *size = read_sz;
    return SZ_OK;
}

static SRes FileInStream_fmap_Seek(void *pp, Int64 *pos, ESzSeek origin) {
    CFileInStream *p = (CFileInStream *)pp;

    switch (origin) {
    case SZ_SEEK_SET:
	p->s.curpos = *pos;
	break;
    case SZ_SEEK_CUR:
	p->s.curpos += *pos;
	*pos = p->s.curpos;
	break;
    case SZ_SEEK_END:
	p->s.curpos = p->file.fmap->len + *pos;
	*pos = p->s.curpos;
	break;
    default:
	return 1;
    }
    return 0;
}

#define UTFBUFSZ 256
int cli_7unz (cli_ctx *ctx, size_t offset) {
    CFileInStream archiveStream;
    CLookToRead lookStream;
    CSzArEx db;
    SRes res;
    UInt16 utf16buf[UTFBUFSZ], *utf16name = utf16buf;
    int namelen = UTFBUFSZ, found = CL_CLEAN;
    Int64 begin_of_archive = offset;
    UInt32 viruses_found = 0;

    /* Replacement for 
       FileInStream_CreateVTable(&archiveStream); */
    archiveStream.s.Read = FileInStream_fmap_Read;
    archiveStream.s.Seek = FileInStream_fmap_Seek;
    archiveStream.s.curpos = 0;
    archiveStream.file.fmap = *ctx->fmap;

    LookToRead_CreateVTable(&lookStream, False);
  
    if(archiveStream.s.Seek(&archiveStream.s, &begin_of_archive, SZ_SEEK_SET) != 0)
	return CL_CLEAN;

    lookStream.realStream = &archiveStream.s;
    LookToRead_Init(&lookStream);

    SzArEx_Init(&db);
    res = SzArEx_Open(&db, &lookStream.s, &allocImp, &allocTempImp);
    if(res == SZ_OK) {
	UInt32 i, blockIndex = 0xFFFFFFFF;
	Byte *outBuffer = 0;
	size_t outBufferSize = 0;
	unsigned int encrypted = 0;

	for (i = 0; i < db.db.NumFiles; i++) {
	    size_t offset = 0;
	    size_t outSizeProcessed = 0;
	    const CSzFileItem *f = db.db.Files + i;
	    char *name;
	    size_t j;
	    int newnamelen, fd;

	    if((found = cli_checklimits("7unz", ctx, 0, 0, 0)))
		break;

	    if (f->IsDir)
		continue;

	    if(cli_checklimits("7unz", ctx, f->Size, 0, 0))
		continue;

	    if (!db.FileNameOffsets)
		newnamelen = 0; /* no filename */
	    else {
		newnamelen = SzArEx_GetFileNameUtf16(&db, i, NULL);
		if (newnamelen > namelen) {
		    if(namelen > UTFBUFSZ)
			free(utf16name);
		    utf16name = cli_malloc(newnamelen*2);
		    if(!utf16name) {
			found = CL_EMEM;
			break;
		    }
		    namelen = newnamelen;
		}
		SzArEx_GetFileNameUtf16(&db, i, utf16name);
	    }

	    name = (char *)utf16name;
	    for(j=0; j<(size_t)newnamelen; j++) /* FIXME */
		name[j] = utf16name[j];
	    name[j] = 0;
	    cli_dbgmsg("cli_7unz: extracting %s\n", name);

	    res = SzArEx_Extract(&db, &lookStream.s, i, &blockIndex, &outBuffer, &outBufferSize, &offset, &outSizeProcessed, &allocImp, &allocTempImp);
	    if(res == SZ_ERROR_ENCRYPTED) {
		encrypted = 1;
		if(DETECT_ENCRYPTED) {
		    cli_dbgmsg("cli_7unz: Encrypted files found in archive.\n");
		    cli_append_virus(ctx, "Heuristics.Encrypted.7Zip");
		    viruses_found++;
		    if(!SCAN_ALL) {
			found = CL_VIRUS;
			break;
		    }
		}
	    }
	    if(cli_matchmeta(ctx, name, 0, f->Size, encrypted, i, f->CrcDefined ? f->Crc : 0, NULL)) {
		found = CL_VIRUS;
		viruses_found++;
		if (!SCAN_ALL)
		    break;
	    }
	    if (res != SZ_OK)
		cli_dbgmsg("cli_unz: extraction failed with %d\n", res);
	    else {
		if((found = cli_gentempfd(ctx->engine->tmpdir, &name, &fd)))
		    break;
		    
		cli_dbgmsg("cli_7unz: Saving to %s\n", name);
		if((size_t)cli_writen(fd, outBuffer + offset, outSizeProcessed) != outSizeProcessed)
		    found = CL_EWRITE;
		else
		    if ((found = cli_magic_scandesc(fd, ctx)) == CL_VIRUS)
			viruses_found++;
		close(fd);
		if(!ctx->engine->keeptmp && cli_unlink(name))
		    found = CL_EUNLINK;

		free(name);
		if(found != CL_CLEAN)
		    if (!(SCAN_ALL && found == CL_VIRUS))
			break;
	    }
	}
	IAlloc_Free(&allocImp, outBuffer);
    }
    SzArEx_Free(&db, &allocImp);
    if(namelen > UTFBUFSZ)
	free(utf16name);

    if (res == SZ_OK)
	cli_dbgmsg("cli_7unz: completed successfully\n");
    else if (res == SZ_ERROR_UNSUPPORTED)
	cli_dbgmsg("cli_7unz: unsupported\n");
    else if (res == SZ_ERROR_MEM)
	cli_dbgmsg("cli_7unz: oom\n");
    else if (res == SZ_ERROR_CRC)
	cli_dbgmsg("cli_7unz: crc mismatch\n");
    else
	cli_dbgmsg("cli_7unz: error %d\n", res);

    if (SCAN_ALL && viruses_found)
	return CL_VIRUS;
    return found;
}