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105 lines
3.3 KiB
C
105 lines
3.3 KiB
C
/* Copyright (C) 2007-2016 Open Information Security Foundation
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*
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* You can copy, redistribute or modify this Program under the terms of
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* the GNU General Public License version 2 as published by the Free
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* Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* version 2 along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301, USA.
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*/
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/**
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* \file
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*
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* \author Victor Julien <victor@inliniac.net>
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*
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* Implements the prefilter keyword
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*/
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#include "suricata-common.h"
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#include "decode.h"
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#include "detect.h"
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#include "detect-parse.h"
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#include "detect-content.h"
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#include "detect-prefilter.h"
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#include "util-debug.h"
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static int DetectPrefilterSetup (DetectEngineCtx *, Signature *, const char *);
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void DetectPrefilterRegister(void)
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{
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sigmatch_table[DETECT_PREFILTER].name = "prefilter";
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sigmatch_table[DETECT_PREFILTER].desc = "force a condition to be used as prefilter";
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sigmatch_table[DETECT_PREFILTER].url = DOC_URL DOC_VERSION "/rules/prefilter-keywords.html#prefilter";
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sigmatch_table[DETECT_PREFILTER].Match = NULL;
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sigmatch_table[DETECT_PREFILTER].Setup = DetectPrefilterSetup;
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sigmatch_table[DETECT_PREFILTER].Free = NULL;
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sigmatch_table[DETECT_PREFILTER].RegisterTests = NULL;
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sigmatch_table[DETECT_PREFILTER].flags |= SIGMATCH_NOOPT;
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}
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/**
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* \internal
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* \brief Apply the prefilter keyword to the last match
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* \param det_ctx detection engine ctx
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* \param s signature
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* \param nullstr should be null
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* \retval 0 ok
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* \retval -1 failure
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*/
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static int DetectPrefilterSetup (DetectEngineCtx *de_ctx, Signature *s, const char *nullstr)
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{
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SCEnter();
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if (nullstr != NULL) {
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SCLogError(SC_ERR_INVALID_VALUE, "prefilter has value");
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SCReturnInt(-1);
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}
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if (s->flags & SIG_FLAG_PREFILTER) {
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SCLogError(SC_ERR_INVALID_SIGNATURE, "prefilter already set");
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SCReturnInt(-1);
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}
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SigMatch *sm = DetectGetLastSM(s);
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if (sm == NULL) {
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SCLogError(SC_ERR_INVALID_SIGNATURE, "prefilter needs preceding match");
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SCReturnInt(-1);
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}
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s->init_data->prefilter_sm = sm;
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/* if the sig match is content, prefilter should act like
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* 'fast_pattern' w/o options. */
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if (sm->type == DETECT_CONTENT) {
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DetectContentData *cd = (DetectContentData *)sm->ctx;
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if ((cd->flags & DETECT_CONTENT_NEGATED) &&
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((cd->flags & DETECT_CONTENT_DISTANCE) ||
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(cd->flags & DETECT_CONTENT_WITHIN) ||
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(cd->flags & DETECT_CONTENT_OFFSET) ||
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(cd->flags & DETECT_CONTENT_DEPTH)))
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{
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SCLogError(SC_ERR_INVALID_SIGNATURE, "prefilter; cannot be "
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"used with negated content, along with relative modifiers");
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SCReturnInt(-1);
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}
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cd->flags |= DETECT_CONTENT_FAST_PATTERN;
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} else {
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s->flags |= SIG_FLAG_PREFILTER;
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/* make sure setup function runs for this type. */
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de_ctx->sm_types_prefilter[sm->type] = true;
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}
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SCReturnInt(0);
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}
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