suricata
detect-ssh-hassh-server.c
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1/* Copyright (C) 2007-2020 Open Information Security Foundation
2 *
3 * You can copy, redistribute or modify this Program under the terms of
4 * the GNU General Public License version 2 as published by the Free
5 * Software Foundation.
6 *
7 * This program is distributed in the hope that it will be useful,
8 * but WITHOUT ANY WARRANTY; without even the implied warranty of
9 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
10 * GNU General Public License for more details.
11 *
12 * You should have received a copy of the GNU General Public License
13 * version 2 along with this program; if not, write to the Free Software
14 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
15 * 02110-1301, USA.
16 */
17
18/**
19 * \file
20 *
21 * \author Vadym Malakhatko <v.malakhatko@sirinsoftware.com>
22 */
23
24#include "suricata-common.h"
25#include "threads.h"
26#include "decode.h"
27
28#include "detect.h"
29#include "detect-parse.h"
30#include "detect-content.h"
31
32#include "detect-engine.h"
34#include "detect-engine-mpm.h"
35#include "detect-engine-state.h"
37
38#include "flow.h"
39#include "flow-var.h"
40#include "flow-util.h"
41#include "stream-tcp.h"
42#include "util-debug.h"
43#include "util-unittest.h"
45
46#include "app-layer.h"
47#include "app-layer-parser.h"
48#include "app-layer-ssh.h"
50#include "rust.h"
51
52
53#define KEYWORD_NAME "ssh.hassh.server"
54#define KEYWORD_ALIAS "ssh-hassh-server"
55#define KEYWORD_DOC "ssh-keywords.html#ssh.hassh.server"
56#define BUFFER_NAME "ssh.hassh.server"
57#define BUFFER_DESC "Ssh Client Fingerprinting For Ssh Servers"
58static int g_ssh_hassh_buffer_id = 0;
59
60
61static InspectionBuffer *GetSshData(DetectEngineThreadCtx *det_ctx,
62 const DetectEngineTransforms *transforms, Flow *_f,
63 const uint8_t flow_flags, void *txv, const int list_id)
64{
65
66 SCEnter();
67
68 InspectionBuffer *buffer = InspectionBufferGet(det_ctx, list_id);
69
70 if (buffer->inspect == NULL) {
71 const uint8_t *hasshServer = NULL;
72 uint32_t b_len = 0;
73
74 if (SCSshTxGetHassh(txv, &hasshServer, &b_len, flow_flags) != 1)
75 return NULL;
76 if (hasshServer == NULL || b_len == 0) {
77 SCLogDebug("SSH hassh not set");
78 return NULL;
79 }
80
82 det_ctx, list_id, buffer, hasshServer, b_len, transforms);
83 }
84
85 return buffer;
86}
87
88/**
89 * \brief this function setup the ssh.hassh.server modifier keyword used in the rule
90 *
91 * \param de_ctx Pointer to the Detection Engine Context
92 * \param s Pointer to the Signature to which the current keyword belongs
93 * \param str Should hold an empty string always
94 *
95 * \retval 0 On success
96 * \retval -1 On failure
97 * \retval -2 on failure that should be silent after the first
98 */
99static int DetectSshHasshServerSetup(DetectEngineCtx *de_ctx, Signature *s, const char *arg)
100{
101 if (SCDetectBufferSetActiveList(de_ctx, s, g_ssh_hassh_buffer_id) < 0)
102 return -1;
103
105 return -1;
106
107 /* try to enable Hassh */
108 SCSshEnableHassh();
109
110 /* Check if Hassh is disabled */
111 if (!RunmodeIsUnittests() && !SCSshHasshIsEnabled()) {
113 SCLogError("hassh support is not enabled");
114 }
115 return -2;
116 }
117
118 return 0;
119
120}
121
122static void DetectSshHasshServerHashSetupCallback(const DetectEngineCtx *de_ctx, Signature *s)
123{
124 for (uint32_t x = 0; x < s->init_data->buffer_index; x++) {
125 if (s->init_data->buffers[x].id != (uint32_t)g_ssh_hassh_buffer_id)
126 continue;
127 SigMatch *sm = s->init_data->buffers[x].head;
128 for (; sm != NULL; sm = sm->next) {
129 if (sm->type != DETECT_CONTENT)
130 continue;
131
133
134 uint32_t u;
135 for (u = 0; u < cd->content_len; u++) {
136 if (isupper(cd->content[u])) {
137 cd->content[u] = u8_tolower(cd->content[u]);
138 }
139 }
140
141 SpmDestroyCtx(cd->spm_ctx);
142 cd->spm_ctx =
143 SpmInitCtx(cd->content, cd->content_len, 1, de_ctx->spm_global_thread_ctx);
144 }
145 }
146}
147
148/**
149 * \brief Registration function for hasshServer keyword.
150 */
@ ALPROTO_SSH
int SCDetectBufferSetActiveList(DetectEngineCtx *de_ctx, Signature *s, const int list)
void InspectionBufferSetupAndApplyTransforms(DetectEngineThreadCtx *det_ctx, const int list_id, InspectionBuffer *buffer, const uint8_t *data, const uint32_t data_len, const DetectEngineTransforms *transforms)
setup the buffer with our initial data
InspectionBuffer * InspectionBufferGet(DetectEngineThreadCtx *det_ctx, const int list_id)
void DetectAppLayerMpmRegister(const char *name, int direction, int priority, PrefilterRegisterFunc PrefilterRegister, InspectionBufferGetDataPtr GetData, AppProto alproto, int tx_min_progress)
register an app layer keyword for mpm
int PrefilterGenericMpmRegister(DetectEngineCtx *de_ctx, SigGroupHead *sgh, MpmCtx *mpm_ctx, const DetectBufferMpmRegistry *mpm_reg, int list_id)
@ DETECT_SSH_HASSH_SERVER
Data structures and function prototypes for keeping state for the detection engine.
void DetectBufferTypeSetDescriptionByName(const char *name, const char *desc)
void DetectBufferTypeRegisterSetupCallback(const char *name, void(*SetupCallback)(const DetectEngineCtx *, Signature *))
uint8_t DetectEngineInspectBufferGeneric(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)
Do the content inspection & validation for a signature.
void DetectAppLayerInspectEngineRegister(const char *name, AppProto alproto, uint32_t dir, int progress, InspectEngineFuncPtr Callback, InspectionBufferGetDataPtr GetData)
Registers an app inspection engine.
bool DetectMd5ValidateCallback(const Signature *s, const char **sigerror, const DetectBufferType *map)
void DetectBufferTypeRegisterValidateCallback(const char *name, bool(*ValidateCallback)(const Signature *, const char **sigerror, const DetectBufferType *))
int DetectBufferTypeGetByName(const char *name)
int SCDetectSignatureSetAppProto(Signature *s, AppProto alproto)
bool SigMatchSilentErrorEnabled(const DetectEngineCtx *de_ctx, const enum DetectKeywordId id)
SigTableElmt * sigmatch_table
#define KEYWORD_DOC
#define BUFFER_DESC
#define KEYWORD_ALIAS
void DetectSshHasshServerRegister(void)
Registration function for hasshServer keyword.
#define BUFFER_NAME
#define KEYWORD_NAME
#define SIGMATCH_NOOPT
Definition detect.h:1651
#define SIG_FLAG_TOCLIENT
Definition detect.h:272
#define SIGMATCH_INFO_STICKY_BUFFER
Definition detect.h:1676
DetectEngineCtx * de_ctx
main detection engine ctx
Definition detect.h:932
SpmGlobalThreadCtx * spm_global_thread_ctx
Definition detect.h:986
Flow data structure.
Definition flow.h:356
a single match condition for a signature
Definition detect.h:356
uint16_t type
Definition detect.h:357
struct SigMatch_ * next
Definition detect.h:360
SigMatchCtx * ctx
Definition detect.h:359
const char * url
Definition detect.h:1462
int(* Setup)(DetectEngineCtx *, Signature *, const char *)
Definition detect.h:1441
uint16_t flags
Definition detect.h:1450
const char * desc
Definition detect.h:1461
const char * alias
Definition detect.h:1460
const char * name
Definition detect.h:1459
SignatureInitDataBuffer * buffers
Definition detect.h:647
uint32_t buffer_index
Definition detect.h:648
Signature container.
Definition detect.h:668
SignatureInitData * init_data
Definition detect.h:747
#define u8_tolower(c)
int RunmodeIsUnittests(void)
Definition suricata.c:270
#define SCEnter(...)
Definition util-debug.h:277
#define SCLogDebug(...)
Definition util-debug.h:275
#define SCLogError(...)
Macro used to log ERROR messages.
Definition util-debug.h:267
SpmCtx * SpmInitCtx(const uint8_t *needle, uint16_t needle_len, int nocase, SpmGlobalThreadCtx *global_thread_ctx)
Definition util-spm.c:173
void SpmDestroyCtx(SpmCtx *ctx)
Definition util-spm.c:183