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/* Copyright (C) 2007-2022 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 Mats Klepsland <mats.klepsland@gmail.com>
*
* Implements support for tls.cert_subject keyword.
*/
#include "suricata-common.h"
#include "threads.h"
#include "decode.h"
#include "detect.h"
#include "detect-parse.h"
#include "detect-engine.h"
#include "detect-engine-mpm.h"
#include "detect-engine-prefilter.h"
#include "detect-content.h"
#include "detect-pcre.h"
#include "detect-tls-cert-subject.h"
#include "flow.h"
#include "flow-util.h"
#include "flow-var.h"
#include "util-debug.h"
#include "util-spm.h"
#include "util-print.h"
#include "stream-tcp.h"
#include "app-layer.h"
#include "app-layer-ssl.h"
#include "util-unittest.h"
#include "util-unittest-helper.h"
static int DetectTlsSubjectSetup(DetectEngineCtx *, Signature *, const char *);
#ifdef UNITTESTS
static void DetectTlsSubjectRegisterTests(void);
#endif
static InspectionBuffer *GetData(DetectEngineThreadCtx *det_ctx,
const DetectEngineTransforms *transforms,
Flow *f, const uint8_t flow_flags,
void *txv, const int list_id);
static int g_tls_cert_subject_buffer_id = 0;
/**
* \brief Registration function for keyword: tls.cert_subject
*/
void DetectTlsSubjectRegister(void)
{
sigmatch_table[DETECT_AL_TLS_CERT_SUBJECT].name = "tls.cert_subject";
sigmatch_table[DETECT_AL_TLS_CERT_SUBJECT].alias = "tls_cert_subject";
sigmatch_table[DETECT_AL_TLS_CERT_SUBJECT].desc =
"sticky buffer to match specifically and only on the TLS cert subject buffer";
sigmatch_table[DETECT_AL_TLS_CERT_SUBJECT].url = "/rules/tls-keywords.html#tls-cert-subject";
sigmatch_table[DETECT_AL_TLS_CERT_SUBJECT].Setup = DetectTlsSubjectSetup;
#ifdef UNITTESTS
sigmatch_table[DETECT_AL_TLS_CERT_SUBJECT].RegisterTests = DetectTlsSubjectRegisterTests;
#endif
sigmatch_table[DETECT_AL_TLS_CERT_SUBJECT].flags |= SIGMATCH_NOOPT;
sigmatch_table[DETECT_AL_TLS_CERT_SUBJECT].flags |= SIGMATCH_INFO_STICKY_BUFFER;
DetectAppLayerInspectEngineRegister2("tls.cert_subject", ALPROTO_TLS, SIG_FLAG_TOSERVER,
TLS_STATE_CERT_READY, DetectEngineInspectBufferGeneric, GetData);
DetectAppLayerMpmRegister2("tls.cert_subject", SIG_FLAG_TOSERVER, 2,
PrefilterGenericMpmRegister, GetData, ALPROTO_TLS, TLS_STATE_CERT_READY);
DetectAppLayerInspectEngineRegister2("tls.cert_subject", ALPROTO_TLS, SIG_FLAG_TOCLIENT,
TLS_STATE_CERT_READY, DetectEngineInspectBufferGeneric, GetData);
DetectAppLayerMpmRegister2("tls.cert_subject", SIG_FLAG_TOCLIENT, 2,
PrefilterGenericMpmRegister, GetData, ALPROTO_TLS,
TLS_STATE_CERT_READY);
DetectBufferTypeSupportsMultiInstance("tls.cert_subject");
DetectBufferTypeSetDescriptionByName("tls.cert_subject",
"TLS certificate subject");
g_tls_cert_subject_buffer_id = DetectBufferTypeGetByName("tls.cert_subject");
}
/**
* \brief this function setup the tls.cert_subject modifier 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
* \retval -1 On failure
*/
static int DetectTlsSubjectSetup(DetectEngineCtx *de_ctx, Signature *s, const char *str)
{
if (DetectBufferSetActiveList(de_ctx, s, g_tls_cert_subject_buffer_id) < 0)
return -1;
if (DetectSignatureSetAppProto(s, ALPROTO_TLS) < 0)
return -1;
return 0;
}
static InspectionBuffer *GetData(DetectEngineThreadCtx *det_ctx,
const DetectEngineTransforms *transforms, Flow *f,
const uint8_t flow_flags, void *txv, const int list_id)
{
InspectionBuffer *buffer = InspectionBufferGet(det_ctx, list_id);
if (buffer->inspect == NULL) {
const SSLState *ssl_state = (SSLState *)f->alstate;
const SSLStateConnp *connp;
if (flow_flags & STREAM_TOSERVER) {
connp = &ssl_state->client_connp;
} else {
connp = &ssl_state->server_connp;
}
if (connp->cert0_subject == NULL) {
return NULL;
}
const uint32_t data_len = strlen(connp->cert0_subject);
const uint8_t *data = (uint8_t *)connp->cert0_subject;
InspectionBufferSetup(det_ctx, list_id, buffer, data, data_len);
InspectionBufferApplyTransforms(buffer, transforms);
}
return buffer;
}
#ifdef UNITTESTS
#include "tests/detect-tls-cert-subject.c"
#endif
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