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-rw-r--r--compat.c215
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diff --git a/compat.c b/compat.c
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+/* $OpenBSD: compat.c,v 1.121 2023/02/02 12:10:05 djm Exp $ */
+/*
+ * Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "includes.h"
+
+#include <sys/types.h>
+
+#include <stdlib.h>
+#include <string.h>
+#include <stdarg.h>
+
+#include "xmalloc.h"
+#include "packet.h"
+#include "compat.h"
+#include "log.h"
+#include "match.h"
+#include "kex.h"
+
+/* determine bug flags from SSH protocol banner */
+void
+compat_banner(struct ssh *ssh, const char *version)
+{
+ int i;
+ static struct {
+ char *pat;
+ int bugs;
+ } check[] = {
+ { "OpenSSH_2.*,"
+ "OpenSSH_3.0*,"
+ "OpenSSH_3.1*", SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR|
+ SSH_BUG_SIGTYPE},
+ { "OpenSSH_3.*", SSH_OLD_FORWARD_ADDR|SSH_BUG_SIGTYPE },
+ { "Sun_SSH_1.0*", SSH_BUG_NOREKEY|SSH_BUG_EXTEOF|
+ SSH_BUG_SIGTYPE},
+ { "OpenSSH_2*,"
+ "OpenSSH_3*,"
+ "OpenSSH_4*", SSH_BUG_SIGTYPE },
+ { "OpenSSH_5*", SSH_NEW_OPENSSH|SSH_BUG_DYNAMIC_RPORT|
+ SSH_BUG_SIGTYPE},
+ { "OpenSSH_6.6.1*", SSH_NEW_OPENSSH|SSH_BUG_SIGTYPE},
+ { "OpenSSH_6.5*,"
+ "OpenSSH_6.6*", SSH_NEW_OPENSSH|SSH_BUG_CURVE25519PAD|
+ SSH_BUG_SIGTYPE},
+ { "OpenSSH_7.4*", SSH_NEW_OPENSSH|SSH_BUG_SIGTYPE|
+ SSH_BUG_SIGTYPE74},
+ { "OpenSSH_7.0*,"
+ "OpenSSH_7.1*,"
+ "OpenSSH_7.2*,"
+ "OpenSSH_7.3*,"
+ "OpenSSH_7.5*,"
+ "OpenSSH_7.6*,"
+ "OpenSSH_7.7*", SSH_NEW_OPENSSH|SSH_BUG_SIGTYPE},
+ { "OpenSSH*", SSH_NEW_OPENSSH },
+ { "*MindTerm*", 0 },
+ { "3.0.*", SSH_BUG_DEBUG },
+ { "3.0 SecureCRT*", SSH_OLD_SESSIONID },
+ { "1.7 SecureFX*", SSH_OLD_SESSIONID },
+ { "1.2.18*,"
+ "1.2.19*,"
+ "1.2.20*,"
+ "1.2.21*,"
+ "1.2.22*", SSH_BUG_IGNOREMSG },
+ { "1.3.2*", /* F-Secure */
+ SSH_BUG_IGNOREMSG },
+ { "Cisco-1.*", SSH_BUG_DHGEX_LARGE|
+ SSH_BUG_HOSTKEYS },
+ { "*SSH Compatible Server*", /* Netscreen */
+ SSH_BUG_PASSWORDPAD },
+ { "*OSU_0*,"
+ "OSU_1.0*,"
+ "OSU_1.1*,"
+ "OSU_1.2*,"
+ "OSU_1.3*,"
+ "OSU_1.4*,"
+ "OSU_1.5alpha1*,"
+ "OSU_1.5alpha2*,"
+ "OSU_1.5alpha3*", SSH_BUG_PASSWORDPAD },
+ { "*SSH_Version_Mapper*",
+ SSH_BUG_SCANNER },
+ { "PuTTY_Local:*," /* dev versions < Sep 2014 */
+ "PuTTY-Release-0.5*," /* 0.50-0.57, DH-GEX in >=0.52 */
+ "PuTTY_Release_0.5*," /* 0.58-0.59 */
+ "PuTTY_Release_0.60*,"
+ "PuTTY_Release_0.61*,"
+ "PuTTY_Release_0.62*,"
+ "PuTTY_Release_0.63*,"
+ "PuTTY_Release_0.64*",
+ SSH_OLD_DHGEX },
+ { "FuTTY*", SSH_OLD_DHGEX }, /* Putty Fork */
+ { "Probe-*",
+ SSH_BUG_PROBE },
+ { "TeraTerm SSH*,"
+ "TTSSH/1.5.*,"
+ "TTSSH/2.1*,"
+ "TTSSH/2.2*,"
+ "TTSSH/2.3*,"
+ "TTSSH/2.4*,"
+ "TTSSH/2.5*,"
+ "TTSSH/2.6*,"
+ "TTSSH/2.70*,"
+ "TTSSH/2.71*,"
+ "TTSSH/2.72*", SSH_BUG_HOSTKEYS },
+ { "WinSCP_release_4*,"
+ "WinSCP_release_5.0*,"
+ "WinSCP_release_5.1,"
+ "WinSCP_release_5.1.*,"
+ "WinSCP_release_5.5,"
+ "WinSCP_release_5.5.*,"
+ "WinSCP_release_5.6,"
+ "WinSCP_release_5.6.*,"
+ "WinSCP_release_5.7,"
+ "WinSCP_release_5.7.1,"
+ "WinSCP_release_5.7.2,"
+ "WinSCP_release_5.7.3,"
+ "WinSCP_release_5.7.4",
+ SSH_OLD_DHGEX },
+ { "ConfD-*",
+ SSH_BUG_UTF8TTYMODE },
+ { "Twisted_*", 0 },
+ { "Twisted*", SSH_BUG_DEBUG },
+ { NULL, 0 }
+ };
+
+ /* process table, return first match */
+ ssh->compat = 0;
+ for (i = 0; check[i].pat; i++) {
+ if (match_pattern_list(version, check[i].pat, 0) == 1) {
+ debug_f("match: %s pat %s compat 0x%08x",
+ version, check[i].pat, check[i].bugs);
+ ssh->compat = check[i].bugs;
+ return;
+ }
+ }
+ debug_f("no match: %s", version);
+}
+
+/* Always returns pointer to allocated memory, caller must free. */
+char *
+compat_cipher_proposal(struct ssh *ssh, char *cipher_prop)
+{
+ if (!(ssh->compat & SSH_BUG_BIGENDIANAES))
+ return xstrdup(cipher_prop);
+ debug2_f("original cipher proposal: %s", cipher_prop);
+ if ((cipher_prop = match_filter_denylist(cipher_prop, "aes*")) == NULL)
+ fatal("match_filter_denylist failed");
+ debug2_f("compat cipher proposal: %s", cipher_prop);
+ if (*cipher_prop == '\0')
+ fatal("No supported ciphers found");
+ return cipher_prop;
+}
+
+/* Always returns pointer to allocated memory, caller must free. */
+char *
+compat_pkalg_proposal(struct ssh *ssh, char *pkalg_prop)
+{
+ if (!(ssh->compat & SSH_BUG_RSASIGMD5))
+ return xstrdup(pkalg_prop);
+ debug2_f("original public key proposal: %s", pkalg_prop);
+ if ((pkalg_prop = match_filter_denylist(pkalg_prop, "ssh-rsa")) == NULL)
+ fatal("match_filter_denylist failed");
+ debug2_f("compat public key proposal: %s", pkalg_prop);
+ if (*pkalg_prop == '\0')
+ fatal("No supported PK algorithms found");
+ return pkalg_prop;
+}
+
+/* Always returns pointer to allocated memory, caller must free. */
+char *
+compat_kex_proposal(struct ssh *ssh, char *p)
+{
+ char *cp = NULL, *cp2 = NULL;
+
+ if ((ssh->compat & (SSH_BUG_CURVE25519PAD|SSH_OLD_DHGEX)) == 0)
+ return xstrdup(p);
+ debug2_f("original KEX proposal: %s", p);
+ if ((ssh->compat & SSH_BUG_CURVE25519PAD) != 0)
+ if ((cp = match_filter_denylist(p,
+ "curve25519-sha256@libssh.org")) == NULL)
+ fatal("match_filter_denylist failed");
+ if ((ssh->compat & SSH_OLD_DHGEX) != 0) {
+ if ((cp2 = match_filter_denylist(cp ? cp : p,
+ "diffie-hellman-group-exchange-sha256,"
+ "diffie-hellman-group-exchange-sha1")) == NULL)
+ fatal("match_filter_denylist failed");
+ free(cp);
+ cp = cp2;
+ }
+ if (cp == NULL || *cp == '\0')
+ fatal("No supported key exchange algorithms found");
+ debug2_f("compat KEX proposal: %s", cp);
+ return cp;
+}
+
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