suricata/src/util-file-swf-decompression.c

/* Copyright (C) 2017 Open Information Security Foundation
 *
 * You can copy, redistribute or modify this Program 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
 * version 2 along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 */

/** \file
 *
 * \author Giuseppe Longo <giuseppe@glongo.it>
 *
 */


#include "suricata.h"
#include "suricata-common.h"

#include "app-layer-htp.h"

#include "util-file-decompression.h"
#include "util-file-swf-decompression.h"
#include "util-misc.h"
#include "util-print.h"
#include "util-validate.h"

#include "rust.h"

#include <zlib.h>

/*
 * Return uncompressed file length
 * in little-endian order
 */
uint32_t FileGetSwfDecompressedLen(const uint8_t *buffer,
                                   const uint32_t buffer_len)
{
    if (buffer_len < 8) {
        return 0;
    }

    uint32_t a = buffer[4];
    uint32_t b = buffer[5];
    uint32_t c = buffer[6];
    uint32_t d = buffer[7];

    uint32_t value = (((a & 0xff) << 24UL) |
                      ((b & 0xff) << 16UL) |
                      ((c & 0xff) << 8UL) |
                       (d & 0xff));

    uint32_t len = (((value >> 24) & 0x000000FFUL) |
                    ((value >> 8)  & 0x0000FF00UL) |
                    ((value << 8)  & 0x00FF0000UL) |
                    ((value << 24) & 0xFF000000UL));

    return MIN(MAX_SWF_DECOMPRESSED_LEN, len);
}

uint8_t FileGetSwfVersion(const uint8_t *buffer, const uint32_t buffer_len)
{
    if (buffer_len > 3)
        return buffer[3];

    return 0;
}

static bool FileSwfDecompressionBufferGrow(DetectEngineThreadCtx *det_ctx,
        InspectionBuffer *out_buffer, uint32_t decompressed_data_limit)
{
    const uint32_t maximum_buffer_len = decompressed_data_limit + SWF_HEADER_LEN;
    uint32_t requested_len = out_buffer->size;

    if (requested_len >= maximum_buffer_len)
        return true;

    if (requested_len == 0) {
        requested_len = MIN(SWF_DECOMPRESS_INITIAL_BUFFER_LEN, maximum_buffer_len);
    } else if (requested_len > maximum_buffer_len / 2) {
        requested_len = maximum_buffer_len;
    } else {
        requested_len *= 2;
    }

    if (SCInspectionBufferCheckAndExpand(out_buffer, requested_len) == NULL) {
        DetectEngineSetEvent(det_ctx, FILE_DECODER_EVENT_NO_MEM);
        return false;
    }
    return true;
}

static uint32_t FileSwfDecompressionOutputCapacity(
        const InspectionBuffer *out_buffer, uint32_t decompressed_data_limit)
{
    if (out_buffer->size <= SWF_HEADER_LEN)
        return 0;
    return MIN(out_buffer->size - SWF_HEADER_LEN, decompressed_data_limit);
}

/* CWS format */
/*
 * | 4 bytes         | 4 bytes    | n bytes         |
 * | 'CWS' + version | script len | compressed data |
 */
int FileSwfZlibDecompression(DetectEngineThreadCtx *det_ctx, const uint8_t *compressed_data,
        uint32_t compressed_data_len, InspectionBuffer *out_buffer,
        uint32_t decompressed_data_limit, uint32_t *decompressed_data_produced)
{
    int ret = 1;
    *decompressed_data_produced = 0;
    z_stream infstream;
    memset(&infstream, 0, sizeof(infstream));
    infstream.zalloc = Z_NULL;
    infstream.zfree = Z_NULL;
    infstream.opaque = Z_NULL;

    infstream.avail_in = (uInt)compressed_data_len;
    infstream.next_in = (Bytef *)compressed_data;

    int result = inflateInit(&infstream);
    if (result != Z_OK) {
        DetectEngineSetEvent(det_ctx, FILE_DECODER_EVENT_Z_UNKNOWN_ERROR);
        return 0;
    }

    while (true) {
        uint32_t output_capacity =
                FileSwfDecompressionOutputCapacity(out_buffer, decompressed_data_limit);
        DEBUG_VALIDATE_BUG_ON(infstream.total_out > output_capacity);
        infstream.avail_out = (uInt)(output_capacity - infstream.total_out);
        infstream.next_out = out_buffer->buf + SWF_HEADER_LEN + infstream.total_out;

        result = inflate(&infstream, Z_NO_FLUSH);
        *decompressed_data_produced = (uint32_t)infstream.total_out;

        if (result == Z_STREAM_END || *decompressed_data_produced == decompressed_data_limit)
            break;

        if (result == Z_OK && infstream.avail_in == 0)
            break;

	if (result == Z_OK && infstream.avail_out == 0) {
            if (!FileSwfDecompressionBufferGrow(det_ctx, out_buffer, decompressed_data_limit)) {
                ret = 0;
                break;
            }
            continue;
        }

        if (result == Z_DATA_ERROR) {
            DetectEngineSetEvent(det_ctx, FILE_DECODER_EVENT_Z_DATA_ERROR);
        } else if (result == Z_STREAM_ERROR) {
            DetectEngineSetEvent(det_ctx, FILE_DECODER_EVENT_Z_STREAM_ERROR);
        } else if (result == Z_BUF_ERROR) {
            DetectEngineSetEvent(det_ctx, FILE_DECODER_EVENT_Z_BUF_ERROR);
        } else {
            DetectEngineSetEvent(det_ctx, FILE_DECODER_EVENT_Z_UNKNOWN_ERROR);
        }
        ret = 0;
        break;
    }
    inflateEnd(&infstream);

    return ret;
}

/* ZWS format */
/*
 * | 4 bytes         | 4 bytes    | 4 bytes        | 5 bytes    | n bytes   | 6 bytes         |
 * | 'ZWS' + version | script len | compressed len | LZMA props | LZMA data | LZMA end marker |
 */
int FileSwfLzmaDecompression(DetectEngineThreadCtx *det_ctx, const uint8_t *compressed_data,
        uint32_t compressed_data_len, InspectionBuffer *out_buffer,
        uint32_t decompressed_data_limit, uint32_t *decompressed_data_produced)
{
    int ret = 0;
    *decompressed_data_produced = 0;

    while (true) {
        size_t inprocessed = compressed_data_len;
        size_t outprocessed =
                FileSwfDecompressionOutputCapacity(out_buffer, decompressed_data_limit);

        ret = lzma_decompress(compressed_data, &inprocessed, out_buffer->buf + SWF_HEADER_LEN,
                &outprocessed, MAX_SWF_DECOMPRESSED_LEN);

        if (ret == LzmaOk) {
            *decompressed_data_produced = (uint32_t)outprocessed;
            ret = 1;
            break;
        }
        if (ret == LzmaOutputFull) {
            *decompressed_data_produced = (uint32_t)outprocessed;
            if (*decompressed_data_produced == decompressed_data_limit) {
                ret = 1;
                break;
            }
            if (!FileSwfDecompressionBufferGrow(det_ctx, out_buffer, decompressed_data_limit)) {
                ret = 0;
                break;
            }
            continue;
        }

        if (ret == LzmaIoError) {
            DetectEngineSetEvent(det_ctx, FILE_DECODER_EVENT_LZMA_IO_ERROR);
        } else if (ret == LzmaHeaderTooShortError) {
            DetectEngineSetEvent(det_ctx, FILE_DECODER_EVENT_LZMA_HEADER_TOO_SHORT_ERROR);
        } else if (ret == LzmaError) {
            DetectEngineSetEvent(det_ctx, FILE_DECODER_EVENT_LZMA_DECODER_ERROR);
        } else if (ret == LzmaMemoryError) {
            DetectEngineSetEvent(det_ctx, FILE_DECODER_EVENT_LZMA_MEMLIMIT_ERROR);
        } else if (ret == LzmaXzError) {
            /* We should not see XZ compressed SWF files */
            DEBUG_VALIDATE_BUG_ON(ret == LzmaXzError);
            DetectEngineSetEvent(det_ctx, FILE_DECODER_EVENT_LZMA_XZ_ERROR);
        } else {
            DetectEngineSetEvent(det_ctx, FILE_DECODER_EVENT_LZMA_UNKNOWN_ERROR);
        }
        ret = 0;
        break;
    }

    return ret;
}