/* Copyright (C) 2007-2023 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 Victor Julien <victor@inliniac.net>

 *

 */

#include "suricata-common.h"

#include "threads.h"

#include "decode.h"

#include "detect.h"

#include "detect-parse.h"

#include "detect-content.h"

#include "detect-engine.h"

#include "detect-engine-mpm.h"

#include "detect-engine-prefilter.h"

#include "detect-engine-content-inspection.h"

#include "detect-engine-file.h"

#include "flow.h"

#include "flow-var.h"

#include "flow-util.h"

#include "util-debug.h"

#include "util-spm-bm.h"

#include "util-magic.h"

#include "util-print.h"

#include "util-unittest.h"

#include "util-unittest-helper.h"

#include "util-profiling.h"

#include "app-layer.h"

#include "app-layer-parser.h"

#include "stream-tcp.h"

#include "detect-file-data.h"

#include "detect-filemagic.h"

#include "conf.h"

#ifndef HAVE_MAGIC

static int DetectFilemagicSetupNoSupport (DetectEngineCtx *de_ctx, Signature *s, const char *str)

{

    SCLogError("no libmagic support built in, needed for filemagic keyword");

    return -1;

}

/**

 * \brief Registration function for keyword: filemagic

 */

void DetectFilemagicRegister(void)

{

    sigmatch_table[DETECT_FILEMAGIC].name = "filemagic";

    sigmatch_table[DETECT_FILEMAGIC].desc = "match on the information libmagic returns about a file";

    sigmatch_table[DETECT_FILEMAGIC].url = "/rules/file-keywords.html#filemagic";

    sigmatch_table[DETECT_FILEMAGIC].Setup = DetectFilemagicSetupNoSupport;

    sigmatch_table[DETECT_FILEMAGIC].flags = SIGMATCH_QUOTES_MANDATORY|SIGMATCH_HANDLE_NEGATION;

}

#else /* HAVE_MAGIC */

typedef struct DetectFilemagicThreadData {

    magic_t ctx;

} DetectFilemagicThreadData;

static int DetectFilemagicSetup(DetectEngineCtx *, Signature *, const char *);

static int g_file_match_list_id = 0;

static int DetectFilemagicSetupSticky(DetectEngineCtx *de_ctx, Signature *s, const char *str);

static int g_file_magic_buffer_id = 0;

static int PrefilterMpmFilemagicRegister(DetectEngineCtx *de_ctx, SigGroupHead *sgh,

        MpmCtx *mpm_ctx, const DetectBufferMpmRegistry *mpm_reg, int list_id);

static uint8_t DetectEngineInspectFilemagic(DetectEngineCtx *de_ctx, DetectEngineThreadCtx *det_ctx,

        const DetectEngineAppInspectionEngine *engine, const Signature *s, Flow *f, uint8_t flags,

        void *alstate, void *txv, uint64_t tx_id);

/**

 * \brief Registration function for keyword: filemagic

 */

void DetectFilemagicRegister(void)

{

    sigmatch_table[DETECT_FILEMAGIC].name = "filemagic";

    sigmatch_table[DETECT_FILEMAGIC].desc = "match on the information libmagic returns about a file";

    sigmatch_table[DETECT_FILEMAGIC].url = "/rules/file-keywords.html#filemagic";

    sigmatch_table[DETECT_FILEMAGIC].Setup = DetectFilemagicSetup;

    sigmatch_table[DETECT_FILEMAGIC].flags = SIGMATCH_QUOTES_MANDATORY|SIGMATCH_HANDLE_NEGATION;

    sigmatch_table[DETECT_FILEMAGIC].alternative = DETECT_FILE_MAGIC;

    sigmatch_table[DETECT_FILE_MAGIC].name = "file.magic";

    sigmatch_table[DETECT_FILE_MAGIC].desc = "sticky buffer to match on the file magic";

    sigmatch_table[DETECT_FILE_MAGIC].url = "/rules/file-keywords.html#filemagic";

    sigmatch_table[DETECT_FILE_MAGIC].Setup = DetectFilemagicSetupSticky;

    sigmatch_table[DETECT_FILE_MAGIC].flags = SIGMATCH_NOOPT|SIGMATCH_INFO_STICKY_BUFFER;

    filehandler_table[DETECT_FILE_MAGIC].name = "file.magic",

    filehandler_table[DETECT_FILE_MAGIC].priority = 2;

    filehandler_table[DETECT_FILE_MAGIC].PrefilterFn = PrefilterMpmFilemagicRegister;

    filehandler_table[DETECT_FILE_MAGIC].Callback = DetectEngineInspectFilemagic;

    g_file_match_list_id = DetectBufferTypeRegister("files");

    DetectBufferTypeSetDescriptionByName("file.magic", "file magic");

    DetectBufferTypeSupportsMultiInstance("file.magic");

    g_file_magic_buffer_id = DetectBufferTypeGetByName("file.magic");

  SCLogDebug("registering filemagic rule option");

    return;

}

#define FILEMAGIC_MIN_SIZE  512

/**

 *  \brief run the magic check

 *

 *  \param file the file

 *

 *  \retval -1 error

 *  \retval 0 ok

 */

int FilemagicThreadLookup(magic_t *ctx, File *file)

{

    if (ctx == NULL || file == NULL || FileDataSize(file) == 0) {

        SCReturnInt(-1);

    }

    const uint8_t *data = NULL;

    uint32_t data_len = 0;

    uint64_t offset = 0;

    StreamingBufferGetData(file->sb,

                           &data, &data_len, &offset);

    if (offset == 0) {

        if (FileDataSize(file) >= FILEMAGIC_MIN_SIZE) {

            file->magic = MagicThreadLookup(ctx, data, data_len);

        } else if (file->state >= FILE_STATE_CLOSED) {

            file->magic = MagicThreadLookup(ctx, data, data_len);

        }

    }

    SCReturnInt(0);

}

static void *DetectFilemagicThreadInit(void *data /*@unused@*/)

{

    DetectFilemagicThreadData *t = SCCalloc(1, sizeof(DetectFilemagicThreadData));

    if (unlikely(t == NULL)) {

        SCLogError("couldn't alloc ctx memory");

        return NULL;

    }

    t->ctx = MagicInitContext();

    if (t->ctx == NULL)

        goto error;

    return (void *)t;

error:

    if (t->ctx)

        magic_close(t->ctx);

    SCFree(t);

    return NULL;

}

static void DetectFilemagicThreadFree(void *ctx)

{

    if (ctx != NULL) {

        DetectFilemagicThreadData *t = (DetectFilemagicThreadData *)ctx;

        if (t->ctx)

            magic_close(t->ctx);

        SCFree(t);

    }

}

/**

 * \brief this function is used to parse filemagic options

 * \brief into the current signature

 *

 * \param de_ctx pointer to the Detection Engine Context

 * \param s pointer to the Current Signature

 * \param str pointer to the user provided "filemagic" option

 *

 * \retval 0 on Success

 * \retval -1 on Failure

 */

static int DetectFilemagicSetup (DetectEngineCtx *de_ctx, Signature *s, const char *str)

{

    if (s->init_data->transforms.cnt) {

        SCLogError("previous transforms not consumed before 'filemagic'");

        SCReturnInt(-1);

    }

    s->init_data->list = DETECT_SM_LIST_NOTSET;

    s->file_flags |= (FILE_SIG_NEED_FILE | FILE_SIG_NEED_MAGIC);

    if (DetectContentSetup(de_ctx, s, str) < 0) {

        return -1;

    }

    SigMatch *sm = DetectGetLastSMFromLists(s, DETECT_CONTENT, -1);

    if (sm == NULL)

        return -1;

    DetectContentData *cd = (DetectContentData *)sm->ctx;

    if (DetectContentConvertToNocase(de_ctx, cd) != 0)

        return -1;

    if (DetectEngineContentModifierBufferSetup(

                de_ctx, s, NULL, DETECT_FILE_MAGIC, g_file_magic_buffer_id, s->alproto) < 0)

        return -1;

    if (de_ctx->filemagic_thread_ctx_id == -1) {

        de_ctx->filemagic_thread_ctx_id = DetectRegisterThreadCtxFuncs(

                de_ctx, "filemagic", DetectFilemagicThreadInit, NULL, DetectFilemagicThreadFree, 1);

        if (de_ctx->filemagic_thread_ctx_id == -1)

            return -1;

    }

    return 0;

}

/* file.magic implementation */

/**

 * \brief this function setup the file.magic keyword used in the rule

 *

 * \param de_ctx   Pointer to the Detection Engine Context

 * \param s        Pointer to the Signature to which the current keyword belongs

 * \param str      Should hold an empty string always

 *

 * \retval 0       On success

 */

static int DetectFilemagicSetupSticky(DetectEngineCtx *de_ctx, Signature *s, const char *str)

{

    if (DetectBufferSetActiveList(de_ctx, s, g_file_magic_buffer_id) < 0)

        return -1;

    if (de_ctx->filemagic_thread_ctx_id == -1) {

        de_ctx->filemagic_thread_ctx_id = DetectRegisterThreadCtxFuncs(

                de_ctx, "filemagic", DetectFilemagicThreadInit, NULL, DetectFilemagicThreadFree, 1);

        if (de_ctx->filemagic_thread_ctx_id == -1)

            return -1;

    }

    return 0;

}

static InspectionBuffer *FilemagicGetDataCallback(DetectEngineThreadCtx *det_ctx,

        const DetectEngineTransforms *transforms, Flow *f, uint8_t flow_flags, File *cur_file,

        int list_id, int local_file_id)

{

    SCEnter();

    InspectionBuffer *buffer = InspectionBufferMultipleForListGet(det_ctx, list_id, local_file_id);

    if (buffer == NULL)

        return NULL;

    if (buffer->initialized)

        return buffer;

    if (cur_file->magic == NULL) {

        DetectFilemagicThreadData *tfilemagic =

                (DetectFilemagicThreadData *)DetectThreadCtxGetKeywordThreadCtx(

                        det_ctx, det_ctx->de_ctx->filemagic_thread_ctx_id);

        if (tfilemagic == NULL) {

            InspectionBufferSetupMultiEmpty(buffer);

            return NULL;

        }

        FilemagicThreadLookup(&tfilemagic->ctx, cur_file);

    }

    if (cur_file->magic == NULL) {

        return NULL;

    }

    const uint8_t *data = (const uint8_t *)cur_file->magic;

    uint32_t data_len = (uint32_t)strlen(cur_file->magic);

    InspectionBufferSetupMulti(buffer, transforms, data, data_len);

    SCReturnPtr(buffer, "InspectionBuffer");

}

static uint8_t DetectEngineInspectFilemagic(DetectEngineCtx *de_ctx, DetectEngineThreadCtx *det_ctx,

        const DetectEngineAppInspectionEngine *engine, const Signature *s, Flow *f, uint8_t flags,

        void *alstate, void *txv, uint64_t tx_id)

{

    const DetectEngineTransforms *transforms = NULL;

    if (!engine->mpm) {

        transforms = engine->v2.transforms;

    }

    AppLayerGetFileState files = AppLayerParserGetTxFiles(f, alstate, txv, flags);

    FileContainer *ffc = files.fc;

    if (ffc == NULL) {

        return DETECT_ENGINE_INSPECT_SIG_CANT_MATCH_FILES;

    }

    uint8_t r = DETECT_ENGINE_INSPECT_SIG_NO_MATCH;

    int local_file_id = 0;

    for (File *file = ffc->head; file != NULL; file = file->next) {

        InspectionBuffer *buffer = FilemagicGetDataCallback(

                det_ctx, transforms, f, flags, file, engine->sm_list, local_file_id);

        if (buffer == NULL)

            continue;

        det_ctx->buffer_offset = 0;

        det_ctx->discontinue_matching = 0;

        det_ctx->inspection_recursion_counter = 0;

        int match = DetectEngineContentInspection(de_ctx, det_ctx, s, engine->smd,

                                              NULL, f,

                                              (uint8_t *)buffer->inspect,

                                              buffer->inspect_len,

                                              buffer->inspect_offset, DETECT_CI_FLAGS_SINGLE,

                                              DETECT_ENGINE_CONTENT_INSPECTION_MODE_STATE);

        if (match == 1) {

            return DETECT_ENGINE_INSPECT_SIG_MATCH;

        } else {

            r = DETECT_ENGINE_INSPECT_SIG_CANT_MATCH_FILES;

        }

        local_file_id++;

    }

    return r;

}

typedef struct PrefilterMpmFilemagic {

    int list_id;

    const MpmCtx *mpm_ctx;

    const DetectEngineTransforms *transforms;

} PrefilterMpmFilemagic;

/** \brief Filedata Filedata Mpm prefilter callback

 *

 *  \param det_ctx detection engine thread ctx

 *  \param p packet to inspect

 *  \param f flow to inspect

 *  \param txv tx to inspect

 *  \param pectx inspection context

 */

static void PrefilterTxFilemagic(DetectEngineThreadCtx *det_ctx, const void *pectx, Packet *p,

        Flow *f, void *txv, const uint64_t idx, const AppLayerTxData *txd, const uint8_t flags)

{

    SCEnter();

    if (!AppLayerParserHasFilesInDir(txd, flags))

        return;

    const PrefilterMpmFilemagic *ctx = (const PrefilterMpmFilemagic *)pectx;

    const MpmCtx *mpm_ctx = ctx->mpm_ctx;

    const int list_id = ctx->list_id;

    AppLayerGetFileState files = AppLayerParserGetTxFiles(f, f->alstate, txv, flags);

    FileContainer *ffc = files.fc;

    if (ffc != NULL) {

        int local_file_id = 0;

        for (File *file = ffc->head; file != NULL; file = file->next) {

            InspectionBuffer *buffer = FilemagicGetDataCallback(

                    det_ctx, ctx->transforms, f, flags, file, list_id, local_file_id);

            if (buffer == NULL)

                continue;

            if (buffer->inspect_len >= mpm_ctx->minlen) {

                (void)mpm_table[mpm_ctx->mpm_type].Search(mpm_ctx,

                        &det_ctx->mtcu, &det_ctx->pmq,

                        buffer->inspect, buffer->inspect_len);

                PREFILTER_PROFILING_ADD_BYTES(det_ctx, buffer->inspect_len);

            }

            local_file_id++;

        }

    }

}

static void PrefilterMpmFilemagicFree(void *ptr)

{

    SCFree(ptr);

}

static int PrefilterMpmFilemagicRegister(DetectEngineCtx *de_ctx, SigGroupHead *sgh,

        MpmCtx *mpm_ctx, const DetectBufferMpmRegistry *mpm_reg, int list_id)

{

    PrefilterMpmFilemagic *pectx = SCCalloc(1, sizeof(*pectx));

    if (pectx == NULL)

        return -1;

    pectx->list_id = list_id;

    pectx->mpm_ctx = mpm_ctx;

    pectx->transforms = &mpm_reg->transforms;

    return PrefilterAppendTxEngine(de_ctx, sgh, PrefilterTxFilemagic,

            mpm_reg->app_v2.alproto, mpm_reg->app_v2.tx_min_progress,

            pectx, PrefilterMpmFilemagicFree, mpm_reg->pname);

}

#endif /* HAVE_MAGIC */