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-rw-r--r--LICENCE23
-rw-r--r--Makefile.in2
-rw-r--r--deattack.c165
-rw-r--r--deattack.h38
-rw-r--r--packet.c7
5 files changed, 3 insertions, 232 deletions
diff --git a/LICENCE b/LICENCE
index f52387139..15248212a 100644
--- a/LICENCE
+++ b/LICENCE
@@ -75,27 +75,6 @@ OpenSSH contains no GPL code.
75 PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE 75 PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
76 POSSIBILITY OF SUCH DAMAGES. 76 POSSIBILITY OF SUCH DAMAGES.
77 77
782)
79 The 32-bit CRC compensation attack detector in deattack.c was
80 contributed by CORE SDI S.A. under a BSD-style license.
81
82 * Cryptographic attack detector for ssh - source code
83 *
84 * Copyright (c) 1998 CORE SDI S.A., Buenos Aires, Argentina.
85 *
86 * All rights reserved. Redistribution and use in source and binary
87 * forms, with or without modification, are permitted provided that
88 * this copyright notice is retained.
89 *
90 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
91 * WARRANTIES ARE DISCLAIMED. IN NO EVENT SHALL CORE SDI S.A. BE
92 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY OR
93 * CONSEQUENTIAL DAMAGES RESULTING FROM THE USE OR MISUSE OF THIS
94 * SOFTWARE.
95 *
96 * Ariel Futoransky <futo@core-sdi.com>
97 * <http://www.core-sdi.com>
98
993) 783)
100 ssh-keyscan was contributed by David Mazieres under a BSD-style 79 ssh-keyscan was contributed by David Mazieres under a BSD-style
101 license. 80 license.
@@ -337,4 +316,4 @@ OpenSSH contains no GPL code.
337 316
338 317
339------ 318------
340$OpenBSD: LICENCE,v 1.19 2004/08/30 09:18:08 markus Exp $ 319$OpenBSD: LICENCE,v 1.20 2017/04/30 23:26:16 djm Exp $
diff --git a/Makefile.in b/Makefile.in
index a7a6239c0..d7f17df8c 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -79,7 +79,7 @@ LIBSSH_OBJS=${LIBOPENSSH_OBJS} \
79 authfd.o authfile.o bufaux.o bufbn.o bufec.o buffer.o \ 79 authfd.o authfile.o bufaux.o bufbn.o bufec.o buffer.o \
80 canohost.o channels.o cipher.o cipher-aes.o cipher-aesctr.o \ 80 canohost.o channels.o cipher.o cipher-aes.o cipher-aesctr.o \
81 cipher-ctr.o cleanup.o \ 81 cipher-ctr.o cleanup.o \
82 compat.o crc32.o deattack.o fatal.o hostfile.o \ 82 compat.o crc32.o fatal.o hostfile.o \
83 log.o match.o moduli.o nchan.o packet.o opacket.o \ 83 log.o match.o moduli.o nchan.o packet.o opacket.o \
84 readpass.o rsa.o ttymodes.o xmalloc.o addrmatch.o \ 84 readpass.o rsa.o ttymodes.o xmalloc.o addrmatch.o \
85 atomicio.o key.o dispatch.o mac.o uidswap.o uuencode.o misc.o utf8.o \ 85 atomicio.o key.o dispatch.o mac.o uidswap.o uuencode.o misc.o utf8.o \
diff --git a/deattack.c b/deattack.c
deleted file mode 100644
index e76481a6d..000000000
--- a/deattack.c
+++ /dev/null
@@ -1,165 +0,0 @@
1/* $OpenBSD: deattack.c,v 1.32 2015/01/20 23:14:00 deraadt Exp $ */
2/*
3 * Cryptographic attack detector for ssh - source code
4 *
5 * Copyright (c) 1998 CORE SDI S.A., Buenos Aires, Argentina.
6 *
7 * All rights reserved. Redistribution and use in source and binary
8 * forms, with or without modification, are permitted provided that
9 * this copyright notice is retained.
10 *
11 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
12 * WARRANTIES ARE DISCLAIMED. IN NO EVENT SHALL CORE SDI S.A. BE
13 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY OR
14 * CONSEQUENTIAL DAMAGES RESULTING FROM THE USE OR MISUSE OF THIS
15 * SOFTWARE.
16 *
17 * Ariel Futoransky <futo@core-sdi.com>
18 * <http://www.core-sdi.com>
19 */
20
21#include "includes.h"
22
23#include <string.h>
24#include <stdio.h>
25#include <stdlib.h>
26
27#include "deattack.h"
28#include "crc32.h"
29#include "sshbuf.h"
30#include "misc.h"
31
32/*
33 * CRC attack detection has a worst-case behaviour that is O(N^3) over
34 * the number of identical blocks in a packet. This behaviour can be
35 * exploited to create a limited denial of service attack.
36 *
37 * However, because we are dealing with encrypted data, identical
38 * blocks should only occur every 2^35 maximally-sized packets or so.
39 * Consequently, we can detect this DoS by looking for identical blocks
40 * in a packet.
41 *
42 * The parameter below determines how many identical blocks we will
43 * accept in a single packet, trading off between attack detection and
44 * likelihood of terminating a legitimate connection. A value of 32
45 * corresponds to an average of 2^40 messages before an attack is
46 * misdetected
47 */
48#define MAX_IDENTICAL 32
49
50/* SSH Constants */
51#define SSH_MAXBLOCKS (32 * 1024)
52#define SSH_BLOCKSIZE (8)
53
54/* Hashing constants */
55#define HASH_MINSIZE (8 * 1024)
56#define HASH_ENTRYSIZE (2)
57#define HASH_FACTOR(x) ((x)*3/2)
58#define HASH_UNUSEDCHAR (0xff)
59#define HASH_UNUSED (0xffff)
60#define HASH_IV (0xfffe)
61
62#define HASH_MINBLOCKS (7*SSH_BLOCKSIZE)
63
64
65/* Hash function (Input keys are cipher results) */
66#define HASH(x) PEEK_U32(x)
67
68#define CMP(a, b) (memcmp(a, b, SSH_BLOCKSIZE))
69
70static void
71crc_update(u_int32_t *a, u_int32_t b)
72{
73 b ^= *a;
74 *a = ssh_crc32((u_char *)&b, sizeof(b));
75}
76
77/* detect if a block is used in a particular pattern */
78static int
79check_crc(const u_char *S, const u_char *buf, u_int32_t len)
80{
81 u_int32_t crc;
82 const u_char *c;
83
84 crc = 0;
85 for (c = buf; c < buf + len; c += SSH_BLOCKSIZE) {
86 if (!CMP(S, c)) {
87 crc_update(&crc, 1);
88 crc_update(&crc, 0);
89 } else {
90 crc_update(&crc, 0);
91 crc_update(&crc, 0);
92 }
93 }
94 return crc == 0;
95}
96
97void
98deattack_init(struct deattack_ctx *dctx)
99{
100 bzero(dctx, sizeof(*dctx));
101 dctx->n = HASH_MINSIZE / HASH_ENTRYSIZE;
102}
103
104/* Detect a crc32 compensation attack on a packet */
105int
106detect_attack(struct deattack_ctx *dctx, const u_char *buf, u_int32_t len)
107{
108 u_int32_t i, j, l, same;
109 u_int16_t *tmp;
110 const u_char *c, *d;
111
112 if (len > (SSH_MAXBLOCKS * SSH_BLOCKSIZE) ||
113 len % SSH_BLOCKSIZE != 0)
114 return DEATTACK_ERROR;
115 for (l = dctx->n; l < HASH_FACTOR(len / SSH_BLOCKSIZE); l = l << 2)
116 ;
117
118 if (dctx->h == NULL) {
119 if ((dctx->h = calloc(l, HASH_ENTRYSIZE)) == NULL)
120 return DEATTACK_ERROR;
121 dctx->n = l;
122 } else {
123 if (l > dctx->n) {
124 if ((tmp = reallocarray(dctx->h, l, HASH_ENTRYSIZE))
125 == NULL) {
126 free(dctx->h);
127 dctx->h = NULL;
128 return DEATTACK_ERROR;
129 }
130 dctx->h = tmp;
131 dctx->n = l;
132 }
133 }
134
135 if (len <= HASH_MINBLOCKS) {
136 for (c = buf; c < buf + len; c += SSH_BLOCKSIZE) {
137 for (d = buf; d < c; d += SSH_BLOCKSIZE) {
138 if (!CMP(c, d)) {
139 if ((check_crc(c, buf, len)))
140 return DEATTACK_DETECTED;
141 else
142 break;
143 }
144 }
145 }
146 return DEATTACK_OK;
147 }
148 memset(dctx->h, HASH_UNUSEDCHAR, dctx->n * HASH_ENTRYSIZE);
149
150 for (c = buf, same = j = 0; c < (buf + len); c += SSH_BLOCKSIZE, j++) {
151 for (i = HASH(c) & (dctx->n - 1); dctx->h[i] != HASH_UNUSED;
152 i = (i + 1) & (dctx->n - 1)) {
153 if (!CMP(c, buf + dctx->h[i] * SSH_BLOCKSIZE)) {
154 if (++same > MAX_IDENTICAL)
155 return DEATTACK_DOS_DETECTED;
156 if (check_crc(c, buf, len))
157 return DEATTACK_DETECTED;
158 else
159 break;
160 }
161 }
162 dctx->h[i] = j;
163 }
164 return DEATTACK_OK;
165}
diff --git a/deattack.h b/deattack.h
deleted file mode 100644
index ce67a30ff..000000000
--- a/deattack.h
+++ /dev/null
@@ -1,38 +0,0 @@
1/* $OpenBSD: deattack.h,v 1.11 2015/01/19 19:52:16 markus Exp $ */
2
3/*
4 * Cryptographic attack detector for ssh - Header file
5 *
6 * Copyright (c) 1998 CORE SDI S.A., Buenos Aires, Argentina.
7 *
8 * All rights reserved. Redistribution and use in source and binary
9 * forms, with or without modification, are permitted provided that
10 * this copyright notice is retained.
11 *
12 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
13 * WARRANTIES ARE DISCLAIMED. IN NO EVENT SHALL CORE SDI S.A. BE
14 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY OR
15 * CONSEQUENTIAL DAMAGES RESULTING FROM THE USE OR MISUSE OF THIS
16 * SOFTWARE.
17 *
18 * Ariel Futoransky <futo@core-sdi.com>
19 * <http://www.core-sdi.com>
20 */
21
22#ifndef _DEATTACK_H
23#define _DEATTACK_H
24
25/* Return codes */
26#define DEATTACK_OK 0
27#define DEATTACK_DETECTED 1
28#define DEATTACK_DOS_DETECTED 2
29#define DEATTACK_ERROR 3
30
31struct deattack_ctx {
32 u_int16_t *h;
33 u_int32_t n;
34};
35
36void deattack_init(struct deattack_ctx *);
37int detect_attack(struct deattack_ctx *, const u_char *, u_int32_t);
38#endif
diff --git a/packet.c b/packet.c
index 6cec93372..0e312c514 100644
--- a/packet.c
+++ b/packet.c
@@ -1,4 +1,4 @@
1/* $OpenBSD: packet.c,v 1.250 2017/04/30 23:23:54 djm Exp $ */ 1/* $OpenBSD: packet.c,v 1.251 2017/04/30 23:26:16 djm Exp $ */
2/* 2/*
3 * Author: Tatu Ylonen <ylo@cs.hut.fi> 3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -68,7 +68,6 @@
68 68
69#include "xmalloc.h" 69#include "xmalloc.h"
70#include "crc32.h" 70#include "crc32.h"
71#include "deattack.h"
72#include "compat.h" 71#include "compat.h"
73#include "ssh1.h" 72#include "ssh1.h"
74#include "ssh2.h" 73#include "ssh2.h"
@@ -216,9 +215,6 @@ struct session_state {
216 /* One-off warning about weak ciphers */ 215 /* One-off warning about weak ciphers */
217 int cipher_warning_done; 216 int cipher_warning_done;
218 217
219 /* SSH1 CRC compensation attack detector */
220 struct deattack_ctx deattack;
221
222 /* Hook for fuzzing inbound packets */ 218 /* Hook for fuzzing inbound packets */
223 ssh_packet_hook_fn *hook_in; 219 ssh_packet_hook_fn *hook_in;
224 void *hook_in_ctx; 220 void *hook_in_ctx;
@@ -315,7 +311,6 @@ ssh_packet_set_connection(struct ssh *ssh, int fd_in, int fd_out)
315 return NULL; 311 return NULL;
316 } 312 }
317 state->newkeys[MODE_IN] = state->newkeys[MODE_OUT] = NULL; 313 state->newkeys[MODE_IN] = state->newkeys[MODE_OUT] = NULL;
318 deattack_init(&state->deattack);
319 /* 314 /*
320 * Cache the IP address of the remote connection for use in error 315 * Cache the IP address of the remote connection for use in error
321 * messages that might be generated after the connection has closed. 316 * messages that might be generated after the connection has closed.
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-08 09:58:56 +0000