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suricata/src/detect-tls-subjectaltname.c

130 lines
4.2 KiB
C

/* Copyright (C) 2024 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 Shivani Bhardwaj <shivani@oisf.net>
*
* Implements support for tls.subjectaltname 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-engine-content-inspection.h"
#include "detect-content.h"
#include "detect-tls-subjectaltname.h"
#include "detect-engine-uint.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-profiling.h"
static int DetectTlsSubjectAltNameSetup(DetectEngineCtx *, Signature *, const char *);
static InspectionBuffer *TlsSubjectAltNameGetData(DetectEngineThreadCtx *det_ctx,
const DetectEngineTransforms *transforms, Flow *f, uint8_t flags, void *txv, int list_id,
uint32_t index);
static int g_tls_subjectaltname_buffer_id = 0;
/**
* \brief Registration function for keyword: tls.subjectaltname
*/
void DetectTlsSubjectAltNameRegister(void)
{
sigmatch_table[DETECT_AL_TLS_SUBJECTALTNAME].name = "tls.subjectaltname";
sigmatch_table[DETECT_AL_TLS_SUBJECTALTNAME].desc =
"sticky buffer to match the TLS Subject Alternative Name buffer";
sigmatch_table[DETECT_AL_TLS_SUBJECTALTNAME].url =
"/rules/tls-keywords.html#tls-subjectaltname";
sigmatch_table[DETECT_AL_TLS_SUBJECTALTNAME].Setup = DetectTlsSubjectAltNameSetup;
sigmatch_table[DETECT_AL_TLS_SUBJECTALTNAME].flags |= SIGMATCH_NOOPT;
sigmatch_table[DETECT_AL_TLS_SUBJECTALTNAME].flags |= SIGMATCH_INFO_STICKY_BUFFER;
DetectAppLayerMultiRegister("tls.subjectaltname", ALPROTO_TLS, SIG_FLAG_TOCLIENT, 0,
TlsSubjectAltNameGetData, 2, TLS_STATE_CERT_READY);
DetectBufferTypeSetDescriptionByName("tls.subjectaltname", "TLS Subject Alternative Name");
DetectBufferTypeSupportsMultiInstance("tls.subjectaltname");
g_tls_subjectaltname_buffer_id = DetectBufferTypeGetByName("tls.subjectaltname");
}
/**
* \brief This function setup the tls.subjectaltname sticky buffer keyword
*
* \param de_ctx Pointer to the Detect Engine Context
* \param s Pointer to the Signature to which the keyword belongs
* \param str Should hold an empty string always
*
* \retval 0 On success
* \retval -1 On failure
*/
static int DetectTlsSubjectAltNameSetup(DetectEngineCtx *de_ctx, Signature *s, const char *str)
{
if (DetectBufferSetActiveList(de_ctx, s, g_tls_subjectaltname_buffer_id) < 0)
return -1;
if (DetectSignatureSetAppProto(s, ALPROTO_TLS) < 0)
return -1;
return 0;
}
static InspectionBuffer *TlsSubjectAltNameGetData(DetectEngineThreadCtx *det_ctx,
const DetectEngineTransforms *transforms, Flow *f, uint8_t flags, void *txv, int list_id,
uint32_t idx)
{
SCEnter();
InspectionBuffer *buffer = InspectionBufferMultipleForListGet(det_ctx, list_id, idx);
if (buffer == NULL || buffer->initialized)
return buffer;
const SSLState *ssl_state = (SSLState *)f->alstate;
const SSLStateConnp *connp;
connp = &ssl_state->server_connp;
if (idx >= connp->cert0_sans_len) {
return NULL;
}
InspectionBufferSetupMulti(buffer, transforms, (const uint8_t *)connp->cert0_sans[idx],
strlen(connp->cert0_sans[idx]));
buffer->flags = DETECT_CI_FLAGS_SINGLE;
SCReturnPtr(buffer, "InspectionBuffer");
}