diff options
Diffstat (limited to '')
| -rw-r--r-- | debian/patches/gssapi.patch | 4156 |
1 files changed, 4156 insertions, 0 deletions
diff --git a/debian/patches/gssapi.patch b/debian/patches/gssapi.patch new file mode 100644 index 0000000..072c079 --- /dev/null +++ b/debian/patches/gssapi.patch @@ -0,0 +1,4156 @@ +From 61798b25a23b55d72a86a35062106cc3fc0ab834 Mon Sep 17 00:00:00 2001 +From: Simon Wilkinson <simon@sxw.org.uk> +Date: Sun, 9 Feb 2014 16:09:48 +0000 +Subject: GSSAPI key exchange support + +This patch has been rejected upstream: "None of the OpenSSH developers are +in favour of adding this, and this situation has not changed for several +years. This is not a slight on Simon's patch, which is of fine quality, but +just that a) we don't trust GSSAPI implementations that much and b) we don't +like adding new KEX since they are pre-auth attack surface. This one is +particularly scary, since it requires hooks out to typically root-owned +system resources." + +However, quite a lot of people rely on this in Debian, and it's better to +have it merged into the main openssh package rather than having separate +-krb5 packages (as we used to have). It seems to have a generally good +security history. + +Author: Simon Wilkinson <simon@sxw.org.uk> +Author: Colin Watson <cjwatson@debian.org> +Author: Jakub Jelen <jjelen@redhat.com> +Origin: other, https://github.com/openssh-gsskex/openssh-gsskex/pull/23 +Bug: https://bugzilla.mindrot.org/show_bug.cgi?id=1242 +Last-Updated: 2023-01-02 + +Patch-Name: gssapi.patch +--- + Makefile.in | 5 +- + README.md | 36 +++ + auth.c | 94 +------- + auth2-gss.c | 56 ++++- + auth2.c | 2 + + canohost.c | 91 ++++++++ + canohost.h | 3 + + clientloop.c | 13 ++ + configure.ac | 24 ++ + gss-genr.c | 297 +++++++++++++++++++++++- + gss-serv-krb5.c | 87 ++++++- + gss-serv.c | 205 +++++++++++++++-- + kex.c | 66 +++++- + kex.h | 29 +++ + kexdh.c | 10 + + kexgen.c | 2 +- + kexgssc.c | 599 ++++++++++++++++++++++++++++++++++++++++++++++++ + kexgsss.c | 474 ++++++++++++++++++++++++++++++++++++++ + monitor.c | 139 ++++++++++- + monitor.h | 2 + + monitor_wrap.c | 57 ++++- + monitor_wrap.h | 4 +- + readconf.c | 74 ++++++ + readconf.h | 6 + + servconf.c | 47 ++++ + servconf.h | 3 + + session.c | 10 +- + ssh-gss.h | 54 ++++- + ssh-null.c | 108 +++++++++ + ssh.1 | 8 + + ssh.c | 6 +- + ssh_config | 2 + + ssh_config.5 | 57 +++++ + sshconnect2.c | 156 ++++++++++++- + sshd.c | 62 ++++- + sshd_config | 2 + + sshd_config.5 | 30 +++ + sshkey.c | 8 +- + sshkey.h | 1 + + 39 files changed, 2765 insertions(+), 164 deletions(-) + create mode 100644 kexgssc.c + create mode 100644 kexgsss.c + create mode 100644 ssh-null.c + +diff --git a/Makefile.in b/Makefile.in +index c0ebfa041..32b607719 100644 +--- a/Makefile.in ++++ b/Makefile.in +@@ -101,7 +101,7 @@ LIBSSH_OBJS=${LIBOPENSSH_OBJS} \ + readpass.o ttymodes.o xmalloc.o addr.o addrmatch.o \ + atomicio.o dispatch.o mac.o misc.o utf8.o \ + monitor_fdpass.o rijndael.o ssh-dss.o ssh-ecdsa.o ssh-ecdsa-sk.o \ +- ssh-ed25519-sk.o ssh-rsa.o dh.o \ ++ ssh-ed25519-sk.o ssh-rsa.o ssh-null.o dh.o \ + msg.o progressmeter.o dns.o entropy.o gss-genr.o umac.o umac128.o \ + ssh-pkcs11.o smult_curve25519_ref.o \ + poly1305.o chacha.o cipher-chachapoly.o cipher-chachapoly-libcrypto.o \ +@@ -110,6 +110,7 @@ LIBSSH_OBJS=${LIBOPENSSH_OBJS} \ + kex.o kexdh.o kexgex.o kexecdh.o kexc25519.o \ + kexgexc.o kexgexs.o \ + kexsntrup761x25519.o sntrup761.o kexgen.o \ ++ kexgssc.o \ + sftp-realpath.o platform-pledge.o platform-tracing.o platform-misc.o \ + sshbuf-io.o + +@@ -126,7 +127,7 @@ SSHDOBJS=sshd.o auth-rhosts.o auth-passwd.o \ + auth-bsdauth.o auth2-hostbased.o auth2-kbdint.o \ + auth2-none.o auth2-passwd.o auth2-pubkey.o auth2-pubkeyfile.o \ + monitor.o monitor_wrap.o auth-krb5.o \ +- auth2-gss.o gss-serv.o gss-serv-krb5.o \ ++ auth2-gss.o gss-serv.o gss-serv-krb5.o kexgsss.o \ + loginrec.o auth-pam.o auth-shadow.o auth-sia.o \ + srclimit.o sftp-server.o sftp-common.o \ + sandbox-null.o sandbox-rlimit.o sandbox-systrace.o sandbox-darwin.o \ +diff --git a/README.md b/README.md +index 3da933817..a338802ff 100644 +--- a/README.md ++++ b/README.md +@@ -1,3 +1,39 @@ ++Portable OpenSSH with GSSAPI Key Exchange patches ++================================================= ++ ++[](https://lgtm.com/projects/g/openssh-gsskex/openssh-gsskex/context:cpp) ++ ++Currently, there are two branches with gssapi key exchange related ++patches: ++ ++ * fedora/master: Changes that are shipped in Fedora [](https://travis-ci.org/openssh-gsskex/openssh-gsskex) ++ * debian/master: Changes that are shipped in Debian [](https://travis-ci.org/openssh-gsskex/openssh-gsskex) ++ ++The target is to converge to a shared repository with single master ++branch from where we could build releases for both OSes. ++ ++ ++What is in: ++ ++ * The original patch implementing missing parts of RFC4462 by Simon Wilkinson ++ adapted to the current OpenSSH versions and with several fixes ++ * New methods for GSSAPI Kex from IETF draft [1] from Jakub Jelen ++ ++ ++Missing kerberos-related parts: ++ ++ * .k5login and .kusers support available in Fedora [2] [3]. ++ * Improved handling of kerberos ccache location [4] ++ ++ ++ ++[1] https://tools.ietf.org/html/draft-ietf-curdle-gss-keyex-sha2-08 ++[2] https://src.fedoraproject.org/rpms/openssh/blob/master/f/openssh-6.6p1-kuserok.patch ++[3] https://src.fedoraproject.org/rpms/openssh/blob/master/f/openssh-6.6p1-GSSAPIEnablek5users.patch ++[4] https://bugzilla.mindrot.org/show_bug.cgi?id=2775 ++ ++------------------------------------------------------------------------------- ++ + # Portable OpenSSH + + [](https://github.com/openssh/openssh-portable/actions/workflows/c-cpp.yml) +diff --git a/auth.c b/auth.c +index 03a777cce..946dc6074 100644 +--- a/auth.c ++++ b/auth.c +@@ -358,7 +358,8 @@ auth_root_allowed(struct ssh *ssh, const char *method) + case PERMIT_NO_PASSWD: + if (strcmp(method, "publickey") == 0 || + strcmp(method, "hostbased") == 0 || +- strcmp(method, "gssapi-with-mic") == 0) ++ strcmp(method, "gssapi-with-mic") == 0 || ++ strcmp(method, "gssapi-keyex") == 0) + return 1; + break; + case PERMIT_FORCED_ONLY: +@@ -638,97 +639,6 @@ fakepw(void) + return (&fake); + } + +-/* +- * Returns the remote DNS hostname as a string. The returned string must not +- * be freed. NB. this will usually trigger a DNS query the first time it is +- * called. +- * This function does additional checks on the hostname to mitigate some +- * attacks on based on conflation of hostnames and IP addresses. +- */ +- +-static char * +-remote_hostname(struct ssh *ssh) +-{ +- struct sockaddr_storage from; +- socklen_t fromlen; +- struct addrinfo hints, *ai, *aitop; +- char name[NI_MAXHOST], ntop2[NI_MAXHOST]; +- const char *ntop = ssh_remote_ipaddr(ssh); +- +- /* Get IP address of client. */ +- fromlen = sizeof(from); +- memset(&from, 0, sizeof(from)); +- if (getpeername(ssh_packet_get_connection_in(ssh), +- (struct sockaddr *)&from, &fromlen) == -1) { +- debug("getpeername failed: %.100s", strerror(errno)); +- return xstrdup(ntop); +- } +- +- ipv64_normalise_mapped(&from, &fromlen); +- if (from.ss_family == AF_INET6) +- fromlen = sizeof(struct sockaddr_in6); +- +- debug3("Trying to reverse map address %.100s.", ntop); +- /* Map the IP address to a host name. */ +- if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name), +- NULL, 0, NI_NAMEREQD) != 0) { +- /* Host name not found. Use ip address. */ +- return xstrdup(ntop); +- } +- +- /* +- * if reverse lookup result looks like a numeric hostname, +- * someone is trying to trick us by PTR record like following: +- * 1.1.1.10.in-addr.arpa. IN PTR 2.3.4.5 +- */ +- memset(&hints, 0, sizeof(hints)); +- hints.ai_socktype = SOCK_DGRAM; /*dummy*/ +- hints.ai_flags = AI_NUMERICHOST; +- if (getaddrinfo(name, NULL, &hints, &ai) == 0) { +- logit("Nasty PTR record \"%s\" is set up for %s, ignoring", +- name, ntop); +- freeaddrinfo(ai); +- return xstrdup(ntop); +- } +- +- /* Names are stored in lowercase. */ +- lowercase(name); +- +- /* +- * Map it back to an IP address and check that the given +- * address actually is an address of this host. This is +- * necessary because anyone with access to a name server can +- * define arbitrary names for an IP address. Mapping from +- * name to IP address can be trusted better (but can still be +- * fooled if the intruder has access to the name server of +- * the domain). +- */ +- memset(&hints, 0, sizeof(hints)); +- hints.ai_family = from.ss_family; +- hints.ai_socktype = SOCK_STREAM; +- if (getaddrinfo(name, NULL, &hints, &aitop) != 0) { +- logit("reverse mapping checking getaddrinfo for %.700s " +- "[%s] failed.", name, ntop); +- return xstrdup(ntop); +- } +- /* Look for the address from the list of addresses. */ +- for (ai = aitop; ai; ai = ai->ai_next) { +- if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2, +- sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 && +- (strcmp(ntop, ntop2) == 0)) +- break; +- } +- freeaddrinfo(aitop); +- /* If we reached the end of the list, the address was not there. */ +- if (ai == NULL) { +- /* Address not found for the host name. */ +- logit("Address %.100s maps to %.600s, but this does not " +- "map back to the address.", ntop, name); +- return xstrdup(ntop); +- } +- return xstrdup(name); +-} +- + /* + * Return the canonical name of the host in the other side of the current + * connection. The host name is cached, so it is efficient to call this +diff --git a/auth2-gss.c b/auth2-gss.c +index 2062609d9..4566d425c 100644 +--- a/auth2-gss.c ++++ b/auth2-gss.c +@@ -1,7 +1,7 @@ + /* $OpenBSD: auth2-gss.c,v 1.33 2021/12/19 22:12:07 djm Exp $ */ + + /* +- * Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved. ++ * Copyright (c) 2001-2007 Simon Wilkinson. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions +@@ -55,6 +55,48 @@ static int input_gssapi_mic(int type, u_int32_t plen, struct ssh *ssh); + static int input_gssapi_exchange_complete(int type, u_int32_t plen, struct ssh *ssh); + static int input_gssapi_errtok(int, u_int32_t, struct ssh *); + ++/* ++ * The 'gssapi_keyex' userauth mechanism. ++ */ ++static int ++userauth_gsskeyex(struct ssh *ssh) ++{ ++ Authctxt *authctxt = ssh->authctxt; ++ int r, authenticated = 0; ++ struct sshbuf *b = NULL; ++ gss_buffer_desc mic, gssbuf; ++ u_char *p; ++ size_t len; ++ ++ if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || ++ (r = sshpkt_get_end(ssh)) != 0) ++ fatal_fr(r, "parsing"); ++ ++ if ((b = sshbuf_new()) == NULL) ++ fatal_f("sshbuf_new failed"); ++ ++ mic.value = p; ++ mic.length = len; ++ ++ ssh_gssapi_buildmic(b, authctxt->user, authctxt->service, ++ "gssapi-keyex", ssh->kex->session_id); ++ ++ if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL) ++ fatal_f("sshbuf_mutable_ptr failed"); ++ gssbuf.length = sshbuf_len(b); ++ ++ /* gss_kex_context is NULL with privsep, so we can't check it here */ ++ if (!GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gss_kex_context, ++ &gssbuf, &mic)))) ++ authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user, ++ authctxt->pw, 1)); ++ ++ sshbuf_free(b); ++ free(mic.value); ++ ++ return (authenticated); ++} ++ + /* + * We only support those mechanisms that we know about (ie ones that we know + * how to check local user kuserok and the like) +@@ -261,7 +303,8 @@ input_gssapi_exchange_complete(int type, u_int32_t plen, struct ssh *ssh) + if ((r = sshpkt_get_end(ssh)) != 0) + fatal_fr(r, "parse packet"); + +- authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user)); ++ authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user, ++ authctxt->pw, 1)); + + if ((!use_privsep || mm_is_monitor()) && + (displayname = ssh_gssapi_displayname()) != NULL) +@@ -307,7 +350,8 @@ input_gssapi_mic(int type, u_int32_t plen, struct ssh *ssh) + gssbuf.length = sshbuf_len(b); + + if (!GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gssctxt, &gssbuf, &mic)))) +- authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user)); ++ authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user, ++ authctxt->pw, 0)); + else + logit("GSSAPI MIC check failed"); + +@@ -327,6 +371,12 @@ input_gssapi_mic(int type, u_int32_t plen, struct ssh *ssh) + return 0; + } + ++Authmethod method_gsskeyex = { ++ "gssapi-keyex", ++ userauth_gsskeyex, ++ &options.gss_authentication ++}; ++ + Authmethod method_gssapi = { + "gssapi-with-mic", + NULL, +diff --git a/auth2.c b/auth2.c +index 6c061934b..44bd49177 100644 +--- a/auth2.c ++++ b/auth2.c +@@ -71,6 +71,7 @@ extern Authmethod method_passwd; + extern Authmethod method_kbdint; + extern Authmethod method_hostbased; + #ifdef GSSAPI ++extern Authmethod method_gsskeyex; + extern Authmethod method_gssapi; + #endif + +@@ -78,6 +79,7 @@ Authmethod *authmethods[] = { + &method_none, + &method_pubkey, + #ifdef GSSAPI ++ &method_gsskeyex, + &method_gssapi, + #endif + &method_passwd, +diff --git a/canohost.c b/canohost.c +index a810da0ee..99f1cd406 100644 +--- a/canohost.c ++++ b/canohost.c +@@ -35,6 +35,97 @@ + #include "canohost.h" + #include "misc.h" + ++/* ++ * Returns the remote DNS hostname as a string. The returned string must not ++ * be freed. NB. this will usually trigger a DNS query the first time it is ++ * called. ++ * This function does additional checks on the hostname to mitigate some ++ * attacks on legacy rhosts-style authentication. ++ */ ++ ++char * ++remote_hostname(struct ssh *ssh) ++{ ++ struct sockaddr_storage from; ++ socklen_t fromlen; ++ struct addrinfo hints, *ai, *aitop; ++ char name[NI_MAXHOST], ntop2[NI_MAXHOST]; ++ const char *ntop = ssh_remote_ipaddr(ssh); ++ ++ /* Get IP address of client. */ ++ fromlen = sizeof(from); ++ memset(&from, 0, sizeof(from)); ++ if (getpeername(ssh_packet_get_connection_in(ssh), ++ (struct sockaddr *)&from, &fromlen) == -1) { ++ debug("getpeername failed: %.100s", strerror(errno)); ++ return xstrdup(ntop); ++ } ++ ++ ipv64_normalise_mapped(&from, &fromlen); ++ if (from.ss_family == AF_INET6) ++ fromlen = sizeof(struct sockaddr_in6); ++ ++ debug3("Trying to reverse map address %.100s.", ntop); ++ /* Map the IP address to a host name. */ ++ if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name), ++ NULL, 0, NI_NAMEREQD) != 0) { ++ /* Host name not found. Use ip address. */ ++ return xstrdup(ntop); ++ } ++ ++ /* ++ * if reverse lookup result looks like a numeric hostname, ++ * someone is trying to trick us by PTR record like following: ++ * 1.1.1.10.in-addr.arpa. IN PTR 2.3.4.5 ++ */ ++ memset(&hints, 0, sizeof(hints)); ++ hints.ai_socktype = SOCK_DGRAM; /*dummy*/ ++ hints.ai_flags = AI_NUMERICHOST; ++ if (getaddrinfo(name, NULL, &hints, &ai) == 0) { ++ logit("Nasty PTR record \"%s\" is set up for %s, ignoring", ++ name, ntop); ++ freeaddrinfo(ai); ++ return xstrdup(ntop); ++ } ++ ++ /* Names are stored in lowercase. */ ++ lowercase(name); ++ ++ /* ++ * Map it back to an IP address and check that the given ++ * address actually is an address of this host. This is ++ * necessary because anyone with access to a name server can ++ * define arbitrary names for an IP address. Mapping from ++ * name to IP address can be trusted better (but can still be ++ * fooled if the intruder has access to the name server of ++ * the domain). ++ */ ++ memset(&hints, 0, sizeof(hints)); ++ hints.ai_family = from.ss_family; ++ hints.ai_socktype = SOCK_STREAM; ++ if (getaddrinfo(name, NULL, &hints, &aitop) != 0) { ++ logit("reverse mapping checking getaddrinfo for %.700s " ++ "[%s] failed.", name, ntop); ++ return xstrdup(ntop); ++ } ++ /* Look for the address from the list of addresses. */ ++ for (ai = aitop; ai; ai = ai->ai_next) { ++ if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2, ++ sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 && ++ (strcmp(ntop, ntop2) == 0)) ++ break; ++ } ++ freeaddrinfo(aitop); ++ /* If we reached the end of the list, the address was not there. */ ++ if (ai == NULL) { ++ /* Address not found for the host name. */ ++ logit("Address %.100s maps to %.600s, but this does not " ++ "map back to the address.", ntop, name); ++ return xstrdup(ntop); ++ } ++ return xstrdup(name); ++} ++ + void + ipv64_normalise_mapped(struct sockaddr_storage *addr, socklen_t *len) + { +diff --git a/canohost.h b/canohost.h +index 26d62855a..0cadc9f18 100644 +--- a/canohost.h ++++ b/canohost.h +@@ -15,6 +15,9 @@ + #ifndef _CANOHOST_H + #define _CANOHOST_H + ++struct ssh; ++ ++char *remote_hostname(struct ssh *); + char *get_peer_ipaddr(int); + int get_peer_port(int); + char *get_local_ipaddr(int); +diff --git a/clientloop.c b/clientloop.c +index fef9efc6c..8f1fac58a 100644 +--- a/clientloop.c ++++ b/clientloop.c +@@ -115,6 +115,10 @@ + #include "ssherr.h" + #include "hostfile.h" + ++#ifdef GSSAPI ++#include "ssh-gss.h" ++#endif ++ + /* Permitted RSA signature algorithms for UpdateHostkeys proofs */ + #define HOSTKEY_PROOF_RSA_ALGS "rsa-sha2-512,rsa-sha2-256" + +@@ -1415,6 +1419,15 @@ client_loop(struct ssh *ssh, int have_pty, int escape_char_arg, + /* Do channel operations. */ + channel_after_poll(ssh, pfd, npfd_active); + ++#ifdef GSSAPI ++ if (!ssh_packet_is_rekeying(ssh) && ++ options.gss_renewal_rekey && ++ ssh_gssapi_credentials_updated(NULL)) { ++ debug("credentials updated - forcing rekey"); ++ need_rekeying = 1; ++ } ++#endif ++ + /* Buffer input from the connection. */ + if (conn_in_ready) + client_process_net_input(ssh); +diff --git a/configure.ac b/configure.ac +index 22fee70f6..75a9e5670 100644 +--- a/configure.ac ++++ b/configure.ac +@@ -756,6 +756,30 @@ int main(void) { if (NSVersionOfRunTimeLibrary("System") >= (60 << 16)) + [Use tunnel device compatibility to OpenBSD]) + AC_DEFINE([SSH_TUN_PREPEND_AF], [1], + [Prepend the address family to IP tunnel traffic]) ++ AC_MSG_CHECKING([if we have the Security Authorization Session API]) ++ AC_TRY_COMPILE([#include <Security/AuthSession.h>], ++ [SessionCreate(0, 0);], ++ [ac_cv_use_security_session_api="yes" ++ AC_DEFINE([USE_SECURITY_SESSION_API], [1], ++ [platform has the Security Authorization Session API]) ++ LIBS="$LIBS -framework Security" ++ AC_MSG_RESULT([yes])], ++ [ac_cv_use_security_session_api="no" ++ AC_MSG_RESULT([no])]) ++ AC_MSG_CHECKING([if we have an in-memory credentials cache]) ++ AC_TRY_COMPILE( ++ [#include <Kerberos/Kerberos.h>], ++ [cc_context_t c; ++ (void) cc_initialize (&c, 0, NULL, NULL);], ++ [AC_DEFINE([USE_CCAPI], [1], ++ [platform uses an in-memory credentials cache]) ++ LIBS="$LIBS -framework Security" ++ AC_MSG_RESULT([yes]) ++ if test "x$ac_cv_use_security_session_api" = "xno"; then ++ AC_MSG_ERROR([*** Need a security framework to use the credentials cache API ***]) ++ fi], ++ [AC_MSG_RESULT([no])] ++ ) + m4_pattern_allow([AU_IPv]) + AC_CHECK_DECL([AU_IPv4], [], + AC_DEFINE([AU_IPv4], [0], [System only supports IPv4 audit records]) +diff --git a/gss-genr.c b/gss-genr.c +index 2cd695e54..9f9745b7f 100644 +--- a/gss-genr.c ++++ b/gss-genr.c +@@ -1,7 +1,7 @@ + /* $OpenBSD: gss-genr.c,v 1.28 2021/01/27 10:05:28 djm Exp $ */ + + /* +- * Copyright (c) 2001-2007 Simon Wilkinson. All rights reserved. ++ * Copyright (c) 2001-2009 Simon Wilkinson. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions +@@ -42,9 +42,33 @@ + #include "sshbuf.h" + #include "log.h" + #include "ssh2.h" ++#include "cipher.h" ++#include "sshkey.h" ++#include "kex.h" ++#include "digest.h" ++#include "packet.h" + + #include "ssh-gss.h" + ++typedef struct { ++ char *encoded; ++ gss_OID oid; ++} ssh_gss_kex_mapping; ++ ++/* ++ * XXX - It would be nice to find a more elegant way of handling the ++ * XXX passing of the key exchange context to the userauth routines ++ */ ++ ++Gssctxt *gss_kex_context = NULL; ++ ++static ssh_gss_kex_mapping *gss_enc2oid = NULL; ++ ++int ++ssh_gssapi_oid_table_ok(void) { ++ return (gss_enc2oid != NULL); ++} ++ + /* sshbuf_get for gss_buffer_desc */ + int + ssh_gssapi_get_buffer_desc(struct sshbuf *b, gss_buffer_desc *g) +@@ -60,6 +84,159 @@ ssh_gssapi_get_buffer_desc(struct sshbuf *b, gss_buffer_desc *g) + return 0; + } + ++/* sshpkt_get of gss_buffer_desc */ ++int ++ssh_gssapi_sshpkt_get_buffer_desc(struct ssh *ssh, gss_buffer_desc *g) ++{ ++ int r; ++ u_char *p; ++ size_t len; ++ ++ if ((r = sshpkt_get_string(ssh, &p, &len)) != 0) ++ return r; ++ g->value = p; ++ g->length = len; ++ return 0; ++} ++ ++/* ++ * Return a list of the gss-group1-sha1 mechanisms supported by this program ++ * ++ * We test mechanisms to ensure that we can use them, to avoid starting ++ * a key exchange with a bad mechanism ++ */ ++ ++char * ++ssh_gssapi_client_mechanisms(const char *host, const char *client, ++ const char *kex) { ++ gss_OID_set gss_supported = NULL; ++ OM_uint32 min_status; ++ ++ if (GSS_ERROR(gss_indicate_mechs(&min_status, &gss_supported))) ++ return NULL; ++ ++ return ssh_gssapi_kex_mechs(gss_supported, ssh_gssapi_check_mechanism, ++ host, client, kex); ++} ++ ++char * ++ssh_gssapi_kex_mechs(gss_OID_set gss_supported, ssh_gssapi_check_fn *check, ++ const char *host, const char *client, const char *kex) { ++ struct sshbuf *buf = NULL; ++ size_t i; ++ int r = SSH_ERR_ALLOC_FAIL; ++ int oidpos, enclen; ++ char *mechs, *encoded; ++ u_char digest[SSH_DIGEST_MAX_LENGTH]; ++ char deroid[2]; ++ struct ssh_digest_ctx *md = NULL; ++ char *s, *cp, *p; ++ ++ if (gss_enc2oid != NULL) { ++ for (i = 0; gss_enc2oid[i].encoded != NULL; i++) ++ free(gss_enc2oid[i].encoded); ++ free(gss_enc2oid); ++ } ++ ++ gss_enc2oid = xmalloc(sizeof(ssh_gss_kex_mapping) * ++ (gss_supported->count + 1)); ++ ++ if ((buf = sshbuf_new()) == NULL) ++ fatal_f("sshbuf_new failed"); ++ ++ oidpos = 0; ++ s = cp = xstrdup(kex); ++ for (i = 0; i < gss_supported->count; i++) { ++ if (gss_supported->elements[i].length < 128 && ++ (*check)(NULL, &(gss_supported->elements[i]), host, client)) { ++ ++ deroid[0] = SSH_GSS_OIDTYPE; ++ deroid[1] = gss_supported->elements[i].length; ++ ++ if ((md = ssh_digest_start(SSH_DIGEST_MD5)) == NULL || ++ (r = ssh_digest_update(md, deroid, 2)) != 0 || ++ (r = ssh_digest_update(md, ++ gss_supported->elements[i].elements, ++ gss_supported->elements[i].length)) != 0 || ++ (r = ssh_digest_final(md, digest, sizeof(digest))) != 0) ++ fatal_fr(r, "digest failed"); ++ ssh_digest_free(md); ++ md = NULL; ++ ++ encoded = xmalloc(ssh_digest_bytes(SSH_DIGEST_MD5) ++ * 2); ++ enclen = __b64_ntop(digest, ++ ssh_digest_bytes(SSH_DIGEST_MD5), encoded, ++ ssh_digest_bytes(SSH_DIGEST_MD5) * 2); ++ ++ cp = strncpy(s, kex, strlen(kex)); ++ for ((p = strsep(&cp, ",")); p && *p != '\0'; ++ (p = strsep(&cp, ","))) { ++ if (sshbuf_len(buf) != 0 && ++ (r = sshbuf_put_u8(buf, ',')) != 0) ++ fatal_fr(r, "sshbuf_put_u8 error"); ++ if ((r = sshbuf_put(buf, p, strlen(p))) != 0 || ++ (r = sshbuf_put(buf, encoded, enclen)) != 0) ++ fatal_fr(r, "sshbuf_put error"); ++ } ++ ++ gss_enc2oid[oidpos].oid = &(gss_supported->elements[i]); ++ gss_enc2oid[oidpos].encoded = encoded; ++ oidpos++; ++ } ++ } ++ free(s); ++ gss_enc2oid[oidpos].oid = NULL; ++ gss_enc2oid[oidpos].encoded = NULL; ++ ++ if ((mechs = sshbuf_dup_string(buf)) == NULL) ++ fatal_f("sshbuf_dup_string failed"); ++ ++ sshbuf_free(buf); ++ ++ if (strlen(mechs) == 0) { ++ free(mechs); ++ mechs = NULL; ++ } ++ ++ return (mechs); ++} ++ ++gss_OID ++ssh_gssapi_id_kex(Gssctxt *ctx, char *name, int kex_type) { ++ int i = 0; ++ ++#define SKIP_KEX_NAME(type) \ ++ case type: \ ++ if (strlen(name) < sizeof(type##_ID)) \ ++ return GSS_C_NO_OID; \ ++ name += sizeof(type##_ID) - 1; \ ++ break; ++ ++ switch (kex_type) { ++ SKIP_KEX_NAME(KEX_GSS_GRP1_SHA1) ++ SKIP_KEX_NAME(KEX_GSS_GRP14_SHA1) ++ SKIP_KEX_NAME(KEX_GSS_GRP14_SHA256) ++ SKIP_KEX_NAME(KEX_GSS_GRP16_SHA512) ++ SKIP_KEX_NAME(KEX_GSS_GEX_SHA1) ++ SKIP_KEX_NAME(KEX_GSS_NISTP256_SHA256) ++ SKIP_KEX_NAME(KEX_GSS_C25519_SHA256) ++ default: ++ return GSS_C_NO_OID; ++ } ++ ++#undef SKIP_KEX_NAME ++ ++ while (gss_enc2oid[i].encoded != NULL && ++ strcmp(name, gss_enc2oid[i].encoded) != 0) ++ i++; ++ ++ if (gss_enc2oid[i].oid != NULL && ctx != NULL) ++ ssh_gssapi_set_oid(ctx, gss_enc2oid[i].oid); ++ ++ return gss_enc2oid[i].oid; ++} ++ + /* Check that the OID in a data stream matches that in the context */ + int + ssh_gssapi_check_oid(Gssctxt *ctx, void *data, size_t len) +@@ -216,7 +393,7 @@ ssh_gssapi_init_ctx(Gssctxt *ctx, int deleg_creds, gss_buffer_desc *recv_tok, + } + + ctx->major = gss_init_sec_context(&ctx->minor, +- GSS_C_NO_CREDENTIAL, &ctx->context, ctx->name, ctx->oid, ++ ctx->client_creds, &ctx->context, ctx->name, ctx->oid, + GSS_C_MUTUAL_FLAG | GSS_C_INTEG_FLAG | deleg_flag, + 0, NULL, recv_tok, NULL, send_tok, flags, NULL); + +@@ -245,9 +422,43 @@ ssh_gssapi_import_name(Gssctxt *ctx, const char *host) + return (ctx->major); + } + ++OM_uint32 ++ssh_gssapi_client_identity(Gssctxt *ctx, const char *name) ++{ ++ gss_buffer_desc gssbuf; ++ gss_name_t gssname; ++ OM_uint32 status; ++ gss_OID_set oidset; ++ ++ gssbuf.value = (void *) name; ++ gssbuf.length = strlen(gssbuf.value); ++ ++ gss_create_empty_oid_set(&status, &oidset); ++ gss_add_oid_set_member(&status, ctx->oid, &oidset); ++ ++ ctx->major = gss_import_name(&ctx->minor, &gssbuf, ++ GSS_C_NT_USER_NAME, &gssname); ++ ++ if (!ctx->major) ++ ctx->major = gss_acquire_cred(&ctx->minor, ++ gssname, 0, oidset, GSS_C_INITIATE, ++ &ctx->client_creds, NULL, NULL); ++ ++ gss_release_name(&status, &gssname); ++ gss_release_oid_set(&status, &oidset); ++ ++ if (ctx->major) ++ ssh_gssapi_error(ctx); ++ ++ return(ctx->major); ++} ++ + OM_uint32 + ssh_gssapi_sign(Gssctxt *ctx, gss_buffer_t buffer, gss_buffer_t hash) + { ++ if (ctx == NULL) ++ return -1; ++ + if ((ctx->major = gss_get_mic(&ctx->minor, ctx->context, + GSS_C_QOP_DEFAULT, buffer, hash))) + ssh_gssapi_error(ctx); +@@ -255,6 +466,19 @@ ssh_gssapi_sign(Gssctxt *ctx, gss_buffer_t buffer, gss_buffer_t hash) + return (ctx->major); + } + ++/* Priviledged when used by server */ ++OM_uint32 ++ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic) ++{ ++ if (ctx == NULL) ++ return -1; ++ ++ ctx->major = gss_verify_mic(&ctx->minor, ctx->context, ++ gssbuf, gssmic, NULL); ++ ++ return (ctx->major); ++} ++ + void + ssh_gssapi_buildmic(struct sshbuf *b, const char *user, const char *service, + const char *context, const struct sshbuf *session_id) +@@ -271,11 +495,16 @@ ssh_gssapi_buildmic(struct sshbuf *b, const char *user, const char *service, + } + + int +-ssh_gssapi_check_mechanism(Gssctxt **ctx, gss_OID oid, const char *host) ++ssh_gssapi_check_mechanism(Gssctxt **ctx, gss_OID oid, const char *host, ++ const char *client) + { + gss_buffer_desc token = GSS_C_EMPTY_BUFFER; + OM_uint32 major, minor; + gss_OID_desc spnego_oid = {6, (void *)"\x2B\x06\x01\x05\x05\x02"}; ++ Gssctxt *intctx = NULL; ++ ++ if (ctx == NULL) ++ ctx = &intctx; + + /* RFC 4462 says we MUST NOT do SPNEGO */ + if (oid->length == spnego_oid.length && +@@ -285,6 +514,10 @@ ssh_gssapi_check_mechanism(Gssctxt **ctx, gss_OID oid, const char *host) + ssh_gssapi_build_ctx(ctx); + ssh_gssapi_set_oid(*ctx, oid); + major = ssh_gssapi_import_name(*ctx, host); ++ ++ if (!GSS_ERROR(major) && client) ++ major = ssh_gssapi_client_identity(*ctx, client); ++ + if (!GSS_ERROR(major)) { + major = ssh_gssapi_init_ctx(*ctx, 0, GSS_C_NO_BUFFER, &token, + NULL); +@@ -294,10 +527,66 @@ ssh_gssapi_check_mechanism(Gssctxt **ctx, gss_OID oid, const char *host) + GSS_C_NO_BUFFER); + } + +- if (GSS_ERROR(major)) ++ if (GSS_ERROR(major) || intctx != NULL) + ssh_gssapi_delete_ctx(ctx); + + return (!GSS_ERROR(major)); + } + ++int ++ssh_gssapi_credentials_updated(Gssctxt *ctxt) { ++ static gss_name_t saved_name = GSS_C_NO_NAME; ++ static OM_uint32 saved_lifetime = 0; ++ static gss_OID saved_mech = GSS_C_NO_OID; ++ static gss_name_t name; ++ static OM_uint32 last_call = 0; ++ OM_uint32 lifetime, now, major, minor; ++ int equal; ++ ++ now = time(NULL); ++ ++ if (ctxt) { ++ debug("Rekey has happened - updating saved versions"); ++ ++ if (saved_name != GSS_C_NO_NAME) ++ gss_release_name(&minor, &saved_name); ++ ++ major = gss_inquire_cred(&minor, GSS_C_NO_CREDENTIAL, ++ &saved_name, &saved_lifetime, NULL, NULL); ++ ++ if (!GSS_ERROR(major)) { ++ saved_mech = ctxt->oid; ++ saved_lifetime+= now; ++ } else { ++ /* Handle the error */ ++ } ++ return 0; ++ } ++ ++ if (now - last_call < 10) ++ return 0; ++ ++ last_call = now; ++ ++ if (saved_mech == GSS_C_NO_OID) ++ return 0; ++ ++ major = gss_inquire_cred(&minor, GSS_C_NO_CREDENTIAL, ++ &name, &lifetime, NULL, NULL); ++ if (major == GSS_S_CREDENTIALS_EXPIRED) ++ return 0; ++ else if (GSS_ERROR(major)) ++ return 0; ++ ++ major = gss_compare_name(&minor, saved_name, name, &equal); ++ gss_release_name(&minor, &name); ++ if (GSS_ERROR(major)) ++ return 0; ++ ++ if (equal && (saved_lifetime < lifetime + now - 10)) ++ return 1; ++ ++ return 0; ++} ++ + #endif /* GSSAPI */ +diff --git a/gss-serv-krb5.c b/gss-serv-krb5.c +index a151bc1e4..ef20401ec 100644 +--- a/gss-serv-krb5.c ++++ b/gss-serv-krb5.c +@@ -1,7 +1,7 @@ + /* $OpenBSD: gss-serv-krb5.c,v 1.9 2018/07/09 21:37:55 markus Exp $ */ + + /* +- * Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved. ++ * Copyright (c) 2001-2007 Simon Wilkinson. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions +@@ -120,7 +120,7 @@ ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client) + krb5_error_code problem; + krb5_principal princ; + OM_uint32 maj_status, min_status; +- int len; ++ const char *new_ccname; + const char *errmsg; + + if (client->creds == NULL) { +@@ -180,11 +180,16 @@ ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client) + return; + } + +- client->store.filename = xstrdup(krb5_cc_get_name(krb_context, ccache)); ++ new_ccname = krb5_cc_get_name(krb_context, ccache); ++ + client->store.envvar = "KRB5CCNAME"; +- len = strlen(client->store.filename) + 6; +- client->store.envval = xmalloc(len); +- snprintf(client->store.envval, len, "FILE:%s", client->store.filename); ++#ifdef USE_CCAPI ++ xasprintf(&client->store.envval, "API:%s", new_ccname); ++ client->store.filename = NULL; ++#else ++ xasprintf(&client->store.envval, "FILE:%s", new_ccname); ++ client->store.filename = xstrdup(new_ccname); ++#endif + + #ifdef USE_PAM + if (options.use_pam) +@@ -193,9 +198,76 @@ ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client) + + krb5_cc_close(krb_context, ccache); + ++ client->store.data = krb_context; ++ + return; + } + ++int ++ssh_gssapi_krb5_updatecreds(ssh_gssapi_ccache *store, ++ ssh_gssapi_client *client) ++{ ++ krb5_ccache ccache = NULL; ++ krb5_principal principal = NULL; ++ char *name = NULL; ++ krb5_error_code problem; ++ OM_uint32 maj_status, min_status; ++ ++ if ((problem = krb5_cc_resolve(krb_context, store->envval, &ccache))) { ++ logit("krb5_cc_resolve(): %.100s", ++ krb5_get_err_text(krb_context, problem)); ++ return 0; ++ } ++ ++ /* Find out who the principal in this cache is */ ++ if ((problem = krb5_cc_get_principal(krb_context, ccache, ++ &principal))) { ++ logit("krb5_cc_get_principal(): %.100s", ++ krb5_get_err_text(krb_context, problem)); ++ krb5_cc_close(krb_context, ccache); ++ return 0; ++ } ++ ++ if ((problem = krb5_unparse_name(krb_context, principal, &name))) { ++ logit("krb5_unparse_name(): %.100s", ++ krb5_get_err_text(krb_context, problem)); ++ krb5_free_principal(krb_context, principal); ++ krb5_cc_close(krb_context, ccache); ++ return 0; ++ } ++ ++ ++ if (strcmp(name,client->exportedname.value)!=0) { ++ debug("Name in local credentials cache differs. Not storing"); ++ krb5_free_principal(krb_context, principal); ++ krb5_cc_close(krb_context, ccache); ++ krb5_free_unparsed_name(krb_context, name); ++ return 0; ++ } ++ krb5_free_unparsed_name(krb_context, name); ++ ++ /* Name matches, so lets get on with it! */ ++ ++ if ((problem = krb5_cc_initialize(krb_context, ccache, principal))) { ++ logit("krb5_cc_initialize(): %.100s", ++ krb5_get_err_text(krb_context, problem)); ++ krb5_free_principal(krb_context, principal); ++ krb5_cc_close(krb_context, ccache); ++ return 0; ++ } ++ ++ krb5_free_principal(krb_context, principal); ++ ++ if ((maj_status = gss_krb5_copy_ccache(&min_status, client->creds, ++ ccache))) { ++ logit("gss_krb5_copy_ccache() failed. Sorry!"); ++ krb5_cc_close(krb_context, ccache); ++ return 0; ++ } ++ ++ return 1; ++} ++ + ssh_gssapi_mech gssapi_kerberos_mech = { + "toWM5Slw5Ew8Mqkay+al2g==", + "Kerberos", +@@ -203,7 +275,8 @@ ssh_gssapi_mech gssapi_kerberos_mech = { + NULL, + &ssh_gssapi_krb5_userok, + NULL, +- &ssh_gssapi_krb5_storecreds ++ &ssh_gssapi_krb5_storecreds, ++ &ssh_gssapi_krb5_updatecreds + }; + + #endif /* KRB5 */ +diff --git a/gss-serv.c b/gss-serv.c +index b5d4bb2d1..4287579ae 100644 +--- a/gss-serv.c ++++ b/gss-serv.c +@@ -1,7 +1,7 @@ + /* $OpenBSD: gss-serv.c,v 1.32 2020/03/13 03:17:07 djm Exp $ */ + + /* +- * Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved. ++ * Copyright (c) 2001-2009 Simon Wilkinson. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions +@@ -44,17 +44,19 @@ + #include "session.h" + #include "misc.h" + #include "servconf.h" ++#include "uidswap.h" + + #include "ssh-gss.h" ++#include "monitor_wrap.h" + + extern ServerOptions options; + + static ssh_gssapi_client gssapi_client = +- { GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER, +- GSS_C_NO_CREDENTIAL, NULL, {NULL, NULL, NULL, NULL}}; ++ { GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER, GSS_C_NO_CREDENTIAL, ++ GSS_C_NO_NAME, NULL, {NULL, NULL, NULL, NULL, NULL}, 0, 0}; + + ssh_gssapi_mech gssapi_null_mech = +- { NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL}; ++ { NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL, NULL}; + + #ifdef KRB5 + extern ssh_gssapi_mech gssapi_kerberos_mech; +@@ -140,6 +142,29 @@ ssh_gssapi_server_ctx(Gssctxt **ctx, gss_OID oid) + return (ssh_gssapi_acquire_cred(*ctx)); + } + ++/* Unprivileged */ ++char * ++ssh_gssapi_server_mechanisms(void) { ++ if (supported_oids == NULL) ++ ssh_gssapi_prepare_supported_oids(); ++ return (ssh_gssapi_kex_mechs(supported_oids, ++ &ssh_gssapi_server_check_mech, NULL, NULL, ++ options.gss_kex_algorithms)); ++} ++ ++/* Unprivileged */ ++int ++ssh_gssapi_server_check_mech(Gssctxt **dum, gss_OID oid, const char *data, ++ const char *dummy) { ++ Gssctxt *ctx = NULL; ++ int res; ++ ++ res = !GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctx, oid))); ++ ssh_gssapi_delete_ctx(&ctx); ++ ++ return (res); ++} ++ + /* Unprivileged */ + void + ssh_gssapi_supported_oids(gss_OID_set *oidset) +@@ -150,7 +175,9 @@ ssh_gssapi_supported_oids(gss_OID_set *oidset) + gss_OID_set supported; + + gss_create_empty_oid_set(&min_status, oidset); +- gss_indicate_mechs(&min_status, &supported); ++ ++ if (GSS_ERROR(gss_indicate_mechs(&min_status, &supported))) ++ return; + + while (supported_mechs[i]->name != NULL) { + if (GSS_ERROR(gss_test_oid_set_member(&min_status, +@@ -276,8 +303,48 @@ OM_uint32 + ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client) + { + int i = 0; ++ int equal = 0; ++ gss_name_t new_name = GSS_C_NO_NAME; ++ gss_buffer_desc ename = GSS_C_EMPTY_BUFFER; ++ ++ if (options.gss_store_rekey && client->used && ctx->client_creds) { ++ if (client->mech->oid.length != ctx->oid->length || ++ (memcmp(client->mech->oid.elements, ++ ctx->oid->elements, ctx->oid->length) !=0)) { ++ debug("Rekeyed credentials have different mechanism"); ++ return GSS_S_COMPLETE; ++ } ++ ++ if ((ctx->major = gss_inquire_cred_by_mech(&ctx->minor, ++ ctx->client_creds, ctx->oid, &new_name, ++ NULL, NULL, NULL))) { ++ ssh_gssapi_error(ctx); ++ return (ctx->major); ++ } + +- gss_buffer_desc ename; ++ ctx->major = gss_compare_name(&ctx->minor, client->name, ++ new_name, &equal); ++ ++ if (GSS_ERROR(ctx->major)) { ++ ssh_gssapi_error(ctx); ++ return (ctx->major); ++ } ++ ++ if (!equal) { ++ debug("Rekeyed credentials have different name"); ++ return GSS_S_COMPLETE; ++ } ++ ++ debug("Marking rekeyed credentials for export"); ++ ++ gss_release_name(&ctx->minor, &client->name); ++ gss_release_cred(&ctx->minor, &client->creds); ++ client->name = new_name; ++ client->creds = ctx->client_creds; ++ ctx->client_creds = GSS_C_NO_CREDENTIAL; ++ client->updated = 1; ++ return GSS_S_COMPLETE; ++ } + + client->mech = NULL; + +@@ -292,6 +359,13 @@ ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client) + if (client->mech == NULL) + return GSS_S_FAILURE; + ++ if (ctx->client_creds && ++ (ctx->major = gss_inquire_cred_by_mech(&ctx->minor, ++ ctx->client_creds, ctx->oid, &client->name, NULL, NULL, NULL))) { ++ ssh_gssapi_error(ctx); ++ return (ctx->major); ++ } ++ + if ((ctx->major = gss_display_name(&ctx->minor, ctx->client, + &client->displayname, NULL))) { + ssh_gssapi_error(ctx); +@@ -309,6 +383,8 @@ ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client) + return (ctx->major); + } + ++ gss_release_buffer(&ctx->minor, &ename); ++ + /* We can't copy this structure, so we just move the pointer to it */ + client->creds = ctx->client_creds; + ctx->client_creds = GSS_C_NO_CREDENTIAL; +@@ -319,11 +395,20 @@ ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client) + void + ssh_gssapi_cleanup_creds(void) + { +- if (gssapi_client.store.filename != NULL) { +- /* Unlink probably isn't sufficient */ +- debug("removing gssapi cred file\"%s\"", +- gssapi_client.store.filename); +- unlink(gssapi_client.store.filename); ++ krb5_ccache ccache = NULL; ++ krb5_error_code problem; ++ ++ if (gssapi_client.store.data != NULL) { ++ if ((problem = krb5_cc_resolve(gssapi_client.store.data, gssapi_client.store.envval, &ccache))) { ++ debug_f("krb5_cc_resolve(): %.100s", ++ krb5_get_err_text(gssapi_client.store.data, problem)); ++ } else if ((problem = krb5_cc_destroy(gssapi_client.store.data, ccache))) { ++ debug_f("krb5_cc_destroy(): %.100s", ++ krb5_get_err_text(gssapi_client.store.data, problem)); ++ } else { ++ krb5_free_context(gssapi_client.store.data); ++ gssapi_client.store.data = NULL; ++ } + } + } + +@@ -356,19 +441,23 @@ ssh_gssapi_do_child(char ***envp, u_int *envsizep) + + /* Privileged */ + int +-ssh_gssapi_userok(char *user) ++ssh_gssapi_userok(char *user, struct passwd *pw, int kex) + { + OM_uint32 lmin; + ++ (void) kex; /* used in privilege separation */ ++ + if (gssapi_client.exportedname.length == 0 || + gssapi_client.exportedname.value == NULL) { + debug("No suitable client data"); + return 0; + } + if (gssapi_client.mech && gssapi_client.mech->userok) +- if ((*gssapi_client.mech->userok)(&gssapi_client, user)) ++ if ((*gssapi_client.mech->userok)(&gssapi_client, user)) { ++ gssapi_client.used = 1; ++ gssapi_client.store.owner = pw; + return 1; +- else { ++ } else { + /* Destroy delegated credentials if userok fails */ + gss_release_buffer(&lmin, &gssapi_client.displayname); + gss_release_buffer(&lmin, &gssapi_client.exportedname); +@@ -382,14 +471,90 @@ ssh_gssapi_userok(char *user) + return (0); + } + +-/* Privileged */ +-OM_uint32 +-ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic) ++/* These bits are only used for rekeying. The unpriviledged child is running ++ * as the user, the monitor is root. ++ * ++ * In the child, we want to : ++ * *) Ask the monitor to store our credentials into the store we specify ++ * *) If it succeeds, maybe do a PAM update ++ */ ++ ++/* Stuff for PAM */ ++ ++#ifdef USE_PAM ++static int ssh_gssapi_simple_conv(int n, const struct pam_message **msg, ++ struct pam_response **resp, void *data) + { +- ctx->major = gss_verify_mic(&ctx->minor, ctx->context, +- gssbuf, gssmic, NULL); ++ return (PAM_CONV_ERR); ++} ++#endif + +- return (ctx->major); ++void ++ssh_gssapi_rekey_creds(void) { ++ int ok; ++#ifdef USE_PAM ++ int ret; ++ pam_handle_t *pamh = NULL; ++ struct pam_conv pamconv = {ssh_gssapi_simple_conv, NULL}; ++ char *envstr; ++#endif ++ ++ if (gssapi_client.store.filename == NULL && ++ gssapi_client.store.envval == NULL && ++ gssapi_client.store.envvar == NULL) ++ return; ++ ++ ok = PRIVSEP(ssh_gssapi_update_creds(&gssapi_client.store)); ++ ++ if (!ok) ++ return; ++ ++ debug("Rekeyed credentials stored successfully"); ++ ++ /* Actually managing to play with the ssh pam stack from here will ++ * be next to impossible. In any case, we may want different options ++ * for rekeying. So, use our own :) ++ */ ++#ifdef USE_PAM ++ if (!use_privsep) { ++ debug("Not even going to try and do PAM with privsep disabled"); ++ return; ++ } ++ ++ ret = pam_start("sshd-rekey", gssapi_client.store.owner->pw_name, ++ &pamconv, &pamh); ++ if (ret) ++ return; ++ ++ xasprintf(&envstr, "%s=%s", gssapi_client.store.envvar, ++ gssapi_client.store.envval); ++ ++ ret = pam_putenv(pamh, envstr); ++ if (!ret) ++ pam_setcred(pamh, PAM_REINITIALIZE_CRED); ++ pam_end(pamh, PAM_SUCCESS); ++#endif ++} ++ ++int ++ssh_gssapi_update_creds(ssh_gssapi_ccache *store) { ++ int ok = 0; ++ ++ /* Check we've got credentials to store */ ++ if (!gssapi_client.updated) ++ return 0; ++ ++ gssapi_client.updated = 0; ++ ++ temporarily_use_uid(gssapi_client.store.owner); ++ if (gssapi_client.mech && gssapi_client.mech->updatecreds) ++ ok = (*gssapi_client.mech->updatecreds)(store, &gssapi_client); ++ else ++ debug("No update function for this mechanism"); ++ ++ restore_uid(); ++ ++ return ok; + } + + /* Privileged */ +diff --git a/kex.c b/kex.c +index 8cdefcf7c..c259e00fc 100644 +--- a/kex.c ++++ b/kex.c +@@ -57,11 +57,16 @@ + #include "misc.h" + #include "dispatch.h" + #include "monitor.h" ++#include "xmalloc.h" + + #include "ssherr.h" + #include "sshbuf.h" + #include "digest.h" + ++#ifdef GSSAPI ++#include "ssh-gss.h" ++#endif ++ + /* prototype */ + static int kex_choose_conf(struct ssh *); + static int kex_input_newkeys(int, u_int32_t, struct ssh *); +@@ -117,15 +122,28 @@ static const struct kexalg kexalgs[] = { + #endif /* HAVE_EVP_SHA256 || !WITH_OPENSSL */ + { NULL, 0, -1, -1}, + }; ++static const struct kexalg gss_kexalgs[] = { ++#ifdef GSSAPI ++ { KEX_GSS_GEX_SHA1_ID, KEX_GSS_GEX_SHA1, 0, SSH_DIGEST_SHA1 }, ++ { KEX_GSS_GRP1_SHA1_ID, KEX_GSS_GRP1_SHA1, 0, SSH_DIGEST_SHA1 }, ++ { KEX_GSS_GRP14_SHA1_ID, KEX_GSS_GRP14_SHA1, 0, SSH_DIGEST_SHA1 }, ++ { KEX_GSS_GRP14_SHA256_ID, KEX_GSS_GRP14_SHA256, 0, SSH_DIGEST_SHA256 }, ++ { KEX_GSS_GRP16_SHA512_ID, KEX_GSS_GRP16_SHA512, 0, SSH_DIGEST_SHA512 }, ++ { KEX_GSS_NISTP256_SHA256_ID, KEX_GSS_NISTP256_SHA256, ++ NID_X9_62_prime256v1, SSH_DIGEST_SHA256 }, ++ { KEX_GSS_C25519_SHA256_ID, KEX_GSS_C25519_SHA256, 0, SSH_DIGEST_SHA256 }, ++#endif ++ { NULL, 0, -1, -1}, ++}; + +-char * +-kex_alg_list(char sep) ++static char * ++kex_alg_list_internal(char sep, const struct kexalg *algs) + { + char *ret = NULL, *tmp; + size_t nlen, rlen = 0; + const struct kexalg *k; + +- for (k = kexalgs; k->name != NULL; k++) { ++ for (k = algs; k->name != NULL; k++) { + if (ret != NULL) + ret[rlen++] = sep; + nlen = strlen(k->name); +@@ -140,6 +158,18 @@ kex_alg_list(char sep) + return ret; + } + ++char * ++kex_alg_list(char sep) ++{ ++ return kex_alg_list_internal(sep, kexalgs); ++} ++ ++char * ++kex_gss_alg_list(char sep) ++{ ++ return kex_alg_list_internal(sep, gss_kexalgs); ++} ++ + static const struct kexalg * + kex_alg_by_name(const char *name) + { +@@ -149,6 +179,10 @@ kex_alg_by_name(const char *name) + if (strcmp(k->name, name) == 0) + return k; + } ++ for (k = gss_kexalgs; k->name != NULL; k++) { ++ if (strncmp(k->name, name, strlen(k->name)) == 0) ++ return k; ++ } + return NULL; + } + +@@ -317,6 +351,29 @@ kex_assemble_names(char **listp, const char *def, const char *all) + return r; + } + ++/* Validate GSS KEX method name list */ ++int ++kex_gss_names_valid(const char *names) ++{ ++ char *s, *cp, *p; ++ ++ if (names == NULL || *names == '\0') ++ return 0; ++ s = cp = xstrdup(names); ++ for ((p = strsep(&cp, ",")); p && *p != '\0'; ++ (p = strsep(&cp, ","))) { ++ if (strncmp(p, "gss-", 4) != 0 ++ || kex_alg_by_name(p) == NULL) { ++ error("Unsupported KEX algorithm \"%.100s\"", p); ++ free(s); ++ return 0; ++ } ++ } ++ debug3("gss kex names ok: [%s]", names); ++ free(s); ++ return 1; ++} ++ + /* put algorithm proposal into buffer */ + int + kex_prop2buf(struct sshbuf *b, char *proposal[PROPOSAL_MAX]) +@@ -719,6 +776,9 @@ kex_free(struct kex *kex) + sshbuf_free(kex->session_id); + sshbuf_free(kex->initial_sig); + sshkey_free(kex->initial_hostkey); ++#ifdef GSSAPI ++ free(kex->gss_host); ++#endif /* GSSAPI */ + free(kex->failed_choice); + free(kex->hostkey_alg); + free(kex->name); +diff --git a/kex.h b/kex.h +index c35329501..240dca89d 100644 +--- a/kex.h ++++ b/kex.h +@@ -102,6 +102,15 @@ enum kex_exchange { + KEX_ECDH_SHA2, + KEX_C25519_SHA256, + KEX_KEM_SNTRUP761X25519_SHA512, ++#ifdef GSSAPI ++ KEX_GSS_GRP1_SHA1, ++ KEX_GSS_GRP14_SHA1, ++ KEX_GSS_GRP14_SHA256, ++ KEX_GSS_GRP16_SHA512, ++ KEX_GSS_GEX_SHA1, ++ KEX_GSS_NISTP256_SHA256, ++ KEX_GSS_C25519_SHA256, ++#endif + KEX_MAX + }; + +@@ -159,6 +168,12 @@ struct kex { + u_int flags; + int hash_alg; + int ec_nid; ++#ifdef GSSAPI ++ int gss_deleg_creds; ++ int gss_trust_dns; ++ char *gss_host; ++ char *gss_client; ++#endif + char *failed_choice; + int (*verify_host_key)(struct sshkey *, struct ssh *); + struct sshkey *(*load_host_public_key)(int, int, struct ssh *); +@@ -180,8 +195,10 @@ struct kex { + + int kex_names_valid(const char *); + char *kex_alg_list(char); ++char *kex_gss_alg_list(char); + char *kex_names_cat(const char *, const char *); + int kex_assemble_names(char **, const char *, const char *); ++int kex_gss_names_valid(const char *); + + int kex_exchange_identification(struct ssh *, int, const char *); + +@@ -209,6 +226,12 @@ int kexgex_client(struct ssh *); + int kexgex_server(struct ssh *); + int kex_gen_client(struct ssh *); + int kex_gen_server(struct ssh *); ++#if defined(GSSAPI) && defined(WITH_OPENSSL) ++int kexgssgex_client(struct ssh *); ++int kexgssgex_server(struct ssh *); ++int kexgss_client(struct ssh *); ++int kexgss_server(struct ssh *); ++#endif + + int kex_dh_keypair(struct kex *); + int kex_dh_enc(struct kex *, const struct sshbuf *, struct sshbuf **, +@@ -241,6 +264,12 @@ int kexgex_hash(int, const struct sshbuf *, const struct sshbuf *, + const BIGNUM *, const u_char *, size_t, + u_char *, size_t *); + ++int kex_gen_hash(int hash_alg, const struct sshbuf *client_version, ++ const struct sshbuf *server_version, const struct sshbuf *client_kexinit, ++ const struct sshbuf *server_kexinit, const struct sshbuf *server_host_key_blob, ++ const struct sshbuf *client_pub, const struct sshbuf *server_pub, ++ const struct sshbuf *shared_secret, u_char *hash, size_t *hashlen); ++ + void kexc25519_keygen(u_char key[CURVE25519_SIZE], u_char pub[CURVE25519_SIZE]) + __attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE))) + __attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE))); +diff --git a/kexdh.c b/kexdh.c +index c1084f214..0faab21b0 100644 +--- a/kexdh.c ++++ b/kexdh.c +@@ -49,13 +49,23 @@ kex_dh_keygen(struct kex *kex) + { + switch (kex->kex_type) { + case KEX_DH_GRP1_SHA1: ++#ifdef GSSAPI ++ case KEX_GSS_GRP1_SHA1: ++#endif + kex->dh = dh_new_group1(); + break; + case KEX_DH_GRP14_SHA1: + case KEX_DH_GRP14_SHA256: ++#ifdef GSSAPI ++ case KEX_GSS_GRP14_SHA1: ++ case KEX_GSS_GRP14_SHA256: ++#endif + kex->dh = dh_new_group14(); + break; + case KEX_DH_GRP16_SHA512: ++#ifdef GSSAPI ++ case KEX_GSS_GRP16_SHA512: ++#endif + kex->dh = dh_new_group16(); + break; + case KEX_DH_GRP18_SHA512: +diff --git a/kexgen.c b/kexgen.c +index 20f3c5711..ca704844e 100644 +--- a/kexgen.c ++++ b/kexgen.c +@@ -44,7 +44,7 @@ + static int input_kex_gen_init(int, u_int32_t, struct ssh *); + static int input_kex_gen_reply(int type, u_int32_t seq, struct ssh *ssh); + +-static int ++int + kex_gen_hash( + int hash_alg, + const struct sshbuf *client_version, +diff --git a/kexgssc.c b/kexgssc.c +new file mode 100644 +index 000000000..1c62740e7 +--- /dev/null ++++ b/kexgssc.c +@@ -0,0 +1,599 @@ ++/* ++ * Copyright (c) 2001-2009 Simon Wilkinson. 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" ++ ++#if defined(GSSAPI) && defined(WITH_OPENSSL) ++ ++#include "includes.h" ++ ++#include <openssl/crypto.h> ++#include <openssl/bn.h> ++ ++#include <string.h> ++ ++#include "xmalloc.h" ++#include "sshbuf.h" ++#include "ssh2.h" ++#include "sshkey.h" ++#include "cipher.h" ++#include "kex.h" ++#include "log.h" ++#include "packet.h" ++#include "dh.h" ++#include "digest.h" ++#include "ssherr.h" ++ ++#include "ssh-gss.h" ++ ++int ++kexgss_client(struct ssh *ssh) ++{ ++ struct kex *kex = ssh->kex; ++ gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER, ++ recv_tok = GSS_C_EMPTY_BUFFER, ++ gssbuf, msg_tok = GSS_C_EMPTY_BUFFER, *token_ptr; ++ Gssctxt *ctxt; ++ OM_uint32 maj_status, min_status, ret_flags; ++ struct sshbuf *server_blob = NULL; ++ struct sshbuf *shared_secret = NULL; ++ struct sshbuf *server_host_key_blob = NULL; ++ struct sshbuf *empty = NULL; ++ u_char *msg; ++ int type = 0; ++ int first = 1; ++ u_char hash[SSH_DIGEST_MAX_LENGTH]; ++ size_t hashlen; ++ u_char c; ++ int r; ++ ++ /* Initialise our GSSAPI world */ ++ ssh_gssapi_build_ctx(&ctxt); ++ if (ssh_gssapi_id_kex(ctxt, kex->name, kex->kex_type) ++ == GSS_C_NO_OID) ++ fatal("Couldn't identify host exchange"); ++ ++ if (ssh_gssapi_import_name(ctxt, kex->gss_host)) ++ fatal("Couldn't import hostname"); ++ ++ if (kex->gss_client && ++ ssh_gssapi_client_identity(ctxt, kex->gss_client)) ++ fatal("Couldn't acquire client credentials"); ++ ++ /* Step 1 */ ++ switch (kex->kex_type) { ++ case KEX_GSS_GRP1_SHA1: ++ case KEX_GSS_GRP14_SHA1: ++ case KEX_GSS_GRP14_SHA256: ++ case KEX_GSS_GRP16_SHA512: ++ r = kex_dh_keypair(kex); ++ break; ++ case KEX_GSS_NISTP256_SHA256: ++ r = kex_ecdh_keypair(kex); ++ break; ++ case KEX_GSS_C25519_SHA256: ++ r = kex_c25519_keypair(kex); ++ break; ++ default: ++ fatal_f("Unexpected KEX type %d", kex->kex_type); ++ } ++ if (r != 0) ++ return r; ++ ++ token_ptr = GSS_C_NO_BUFFER; ++ ++ do { ++ debug("Calling gss_init_sec_context"); ++ ++ maj_status = ssh_gssapi_init_ctx(ctxt, ++ kex->gss_deleg_creds, token_ptr, &send_tok, ++ &ret_flags); ++ ++ if (GSS_ERROR(maj_status)) { ++ /* XXX Useles code: Missing send? */ ++ if (send_tok.length != 0) { ++ if ((r = sshpkt_start(ssh, ++ SSH2_MSG_KEXGSS_CONTINUE)) != 0 || ++ (r = sshpkt_put_string(ssh, send_tok.value, ++ send_tok.length)) != 0) ++ fatal("sshpkt failed: %s", ssh_err(r)); ++ } ++ fatal("gss_init_context failed"); ++ } ++ ++ /* If we've got an old receive buffer get rid of it */ ++ if (token_ptr != GSS_C_NO_BUFFER) ++ gss_release_buffer(&min_status, &recv_tok); ++ ++ if (maj_status == GSS_S_COMPLETE) { ++ /* If mutual state flag is not true, kex fails */ ++ if (!(ret_flags & GSS_C_MUTUAL_FLAG)) ++ fatal("Mutual authentication failed"); ++ ++ /* If integ avail flag is not true kex fails */ ++ if (!(ret_flags & GSS_C_INTEG_FLAG)) ++ fatal("Integrity check failed"); ++ } ++ ++ /* ++ * If we have data to send, then the last message that we ++ * received cannot have been a 'complete'. ++ */ ++ if (send_tok.length != 0) { ++ if (first) { ++ if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_INIT)) != 0 || ++ (r = sshpkt_put_string(ssh, send_tok.value, ++ send_tok.length)) != 0 || ++ (r = sshpkt_put_stringb(ssh, kex->client_pub)) != 0) ++ fatal("failed to construct packet: %s", ssh_err(r)); ++ first = 0; ++ } else { ++ if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_CONTINUE)) != 0 || ++ (r = sshpkt_put_string(ssh, send_tok.value, ++ send_tok.length)) != 0) ++ fatal("failed to construct packet: %s", ssh_err(r)); ++ } ++ if ((r = sshpkt_send(ssh)) != 0) ++ fatal("failed to send packet: %s", ssh_err(r)); ++ gss_release_buffer(&min_status, &send_tok); ++ ++ /* If we've sent them data, they should reply */ ++ do { ++ type = ssh_packet_read(ssh); ++ if (type == SSH2_MSG_KEXGSS_HOSTKEY) { ++ debug("Received KEXGSS_HOSTKEY"); ++ if (server_host_key_blob) ++ fatal("Server host key received more than once"); ++ if ((r = sshpkt_getb_froms(ssh, &server_host_key_blob)) != 0) ++ fatal("Failed to read server host key: %s", ssh_err(r)); ++ } ++ } while (type == SSH2_MSG_KEXGSS_HOSTKEY); ++ ++ switch (type) { ++ case SSH2_MSG_KEXGSS_CONTINUE: ++ debug("Received GSSAPI_CONTINUE"); ++ if (maj_status == GSS_S_COMPLETE) ++ fatal("GSSAPI Continue received from server when complete"); ++ if ((r = ssh_gssapi_sshpkt_get_buffer_desc(ssh, ++ &recv_tok)) != 0 || ++ (r = sshpkt_get_end(ssh)) != 0) ++ fatal("Failed to read token: %s", ssh_err(r)); ++ break; ++ case SSH2_MSG_KEXGSS_COMPLETE: ++ debug("Received GSSAPI_COMPLETE"); ++ if (msg_tok.value != NULL) ++ fatal("Received GSSAPI_COMPLETE twice?"); ++ if ((r = sshpkt_getb_froms(ssh, &server_blob)) != 0 || ++ (r = ssh_gssapi_sshpkt_get_buffer_desc(ssh, ++ &msg_tok)) != 0) ++ fatal("Failed to read message: %s", ssh_err(r)); ++ ++ /* Is there a token included? */ ++ if ((r = sshpkt_get_u8(ssh, &c)) != 0) ++ fatal("sshpkt failed: %s", ssh_err(r)); ++ if (c) { ++ if ((r = ssh_gssapi_sshpkt_get_buffer_desc( ++ ssh, &recv_tok)) != 0) ++ fatal("Failed to read token: %s", ssh_err(r)); ++ /* If we're already complete - protocol error */ ++ if (maj_status == GSS_S_COMPLETE) ++ sshpkt_disconnect(ssh, "Protocol error: received token when complete"); ++ } else { ++ /* No token included */ ++ if (maj_status != GSS_S_COMPLETE) ++ sshpkt_disconnect(ssh, "Protocol error: did not receive final token"); ++ } ++ if ((r = sshpkt_get_end(ssh)) != 0) { ++ fatal("Expecting end of packet."); ++ } ++ break; ++ case SSH2_MSG_KEXGSS_ERROR: ++ debug("Received Error"); ++ if ((r = sshpkt_get_u32(ssh, &maj_status)) != 0 || ++ (r = sshpkt_get_u32(ssh, &min_status)) != 0 || ++ (r = sshpkt_get_string(ssh, &msg, NULL)) != 0 || ++ (r = sshpkt_get_string(ssh, NULL, NULL)) != 0 || /* lang tag */ ++ (r = sshpkt_get_end(ssh)) != 0) ++ fatal("sshpkt_get failed: %s", ssh_err(r)); ++ fatal("GSSAPI Error: \n%.400s", msg); ++ default: ++ sshpkt_disconnect(ssh, "Protocol error: didn't expect packet type %d", ++ type); ++ } ++ token_ptr = &recv_tok; ++ } else { ++ /* No data, and not complete */ ++ if (maj_status != GSS_S_COMPLETE) ++ fatal("Not complete, and no token output"); ++ } ++ } while (maj_status & GSS_S_CONTINUE_NEEDED); ++ ++ /* ++ * We _must_ have received a COMPLETE message in reply from the ++ * server, which will have set server_blob and msg_tok ++ */ ++ ++ if (type != SSH2_MSG_KEXGSS_COMPLETE) ++ fatal("Didn't receive a SSH2_MSG_KEXGSS_COMPLETE when I expected it"); ++ ++ /* compute shared secret */ ++ switch (kex->kex_type) { ++ case KEX_GSS_GRP1_SHA1: ++ case KEX_GSS_GRP14_SHA1: ++ case KEX_GSS_GRP14_SHA256: ++ case KEX_GSS_GRP16_SHA512: ++ r = kex_dh_dec(kex, server_blob, &shared_secret); ++ break; ++ case KEX_GSS_C25519_SHA256: ++ if (sshbuf_ptr(server_blob)[sshbuf_len(server_blob)] & 0x80) ++ fatal("The received key has MSB of last octet set!"); ++ r = kex_c25519_dec(kex, server_blob, &shared_secret); ++ break; ++ case KEX_GSS_NISTP256_SHA256: ++ if (sshbuf_len(server_blob) != 65) ++ fatal("The received NIST-P256 key did not match" ++ "expected length (expected 65, got %zu)", sshbuf_len(server_blob)); ++ ++ if (sshbuf_ptr(server_blob)[0] != POINT_CONVERSION_UNCOMPRESSED) ++ fatal("The received NIST-P256 key does not have first octet 0x04"); ++ ++ r = kex_ecdh_dec(kex, server_blob, &shared_secret); ++ break; ++ default: ++ r = SSH_ERR_INVALID_ARGUMENT; ++ break; ++ } ++ if (r != 0) ++ goto out; ++ ++ if ((empty = sshbuf_new()) == NULL) { ++ r = SSH_ERR_ALLOC_FAIL; ++ goto out; ++ } ++ ++ hashlen = sizeof(hash); ++ if ((r = kex_gen_hash( ++ kex->hash_alg, ++ kex->client_version, ++ kex->server_version, ++ kex->my, ++ kex->peer, ++ (server_host_key_blob ? server_host_key_blob : empty), ++ kex->client_pub, ++ server_blob, ++ shared_secret, ++ hash, &hashlen)) != 0) ++ fatal_f("Unexpected KEX type %d", kex->kex_type); ++ ++ gssbuf.value = hash; ++ gssbuf.length = hashlen; ++ ++ /* Verify that the hash matches the MIC we just got. */ ++ if (GSS_ERROR(ssh_gssapi_checkmic(ctxt, &gssbuf, &msg_tok))) ++ sshpkt_disconnect(ssh, "Hash's MIC didn't verify"); ++ ++ gss_release_buffer(&min_status, &msg_tok); ++ ++ if (kex->gss_deleg_creds) ++ ssh_gssapi_credentials_updated(ctxt); ++ ++ if (gss_kex_context == NULL) ++ gss_kex_context = ctxt; ++ else ++ ssh_gssapi_delete_ctx(&ctxt); ++ ++ if ((r = kex_derive_keys(ssh, hash, hashlen, shared_secret)) == 0) ++ r = kex_send_newkeys(ssh); ++ ++out: ++ explicit_bzero(hash, sizeof(hash)); ++ explicit_bzero(kex->c25519_client_key, sizeof(kex->c25519_client_key)); ++ sshbuf_free(empty); ++ sshbuf_free(server_host_key_blob); ++ sshbuf_free(server_blob); ++ sshbuf_free(shared_secret); ++ sshbuf_free(kex->client_pub); ++ kex->client_pub = NULL; ++ return r; ++} ++ ++int ++kexgssgex_client(struct ssh *ssh) ++{ ++ struct kex *kex = ssh->kex; ++ gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER, ++ recv_tok = GSS_C_EMPTY_BUFFER, gssbuf, ++ msg_tok = GSS_C_EMPTY_BUFFER, *token_ptr; ++ Gssctxt *ctxt; ++ OM_uint32 maj_status, min_status, ret_flags; ++ struct sshbuf *shared_secret = NULL; ++ BIGNUM *p = NULL; ++ BIGNUM *g = NULL; ++ struct sshbuf *buf = NULL; ++ struct sshbuf *server_host_key_blob = NULL; ++ struct sshbuf *server_blob = NULL; ++ BIGNUM *dh_server_pub = NULL; ++ u_char *msg; ++ int type = 0; ++ int first = 1; ++ u_char hash[SSH_DIGEST_MAX_LENGTH]; ++ size_t hashlen; ++ const BIGNUM *pub_key, *dh_p, *dh_g; ++ int nbits = 0, min = DH_GRP_MIN, max = DH_GRP_MAX; ++ struct sshbuf *empty = NULL; ++ u_char c; ++ int r; ++ ++ /* Initialise our GSSAPI world */ ++ ssh_gssapi_build_ctx(&ctxt); ++ if (ssh_gssapi_id_kex(ctxt, kex->name, kex->kex_type) ++ == GSS_C_NO_OID) ++ fatal("Couldn't identify host exchange"); ++ ++ if (ssh_gssapi_import_name(ctxt, kex->gss_host)) ++ fatal("Couldn't import hostname"); ++ ++ if (kex->gss_client && ++ ssh_gssapi_client_identity(ctxt, kex->gss_client)) ++ fatal("Couldn't acquire client credentials"); ++ ++ debug("Doing group exchange"); ++ nbits = dh_estimate(kex->dh_need * 8); ++ ++ kex->min = DH_GRP_MIN; ++ kex->max = DH_GRP_MAX; ++ kex->nbits = nbits; ++ if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_GROUPREQ)) != 0 || ++ (r = sshpkt_put_u32(ssh, min)) != 0 || ++ (r = sshpkt_put_u32(ssh, nbits)) != 0 || ++ (r = sshpkt_put_u32(ssh, max)) != 0 || ++ (r = sshpkt_send(ssh)) != 0) ++ fatal("Failed to construct a packet: %s", ssh_err(r)); ++ ++ if ((r = ssh_packet_read_expect(ssh, SSH2_MSG_KEXGSS_GROUP)) != 0) ++ fatal("Error: %s", ssh_err(r)); ++ ++ if ((r = sshpkt_get_bignum2(ssh, &p)) != 0 || ++ (r = sshpkt_get_bignum2(ssh, &g)) != 0 || ++ (r = sshpkt_get_end(ssh)) != 0) ++ fatal("shpkt_get_bignum2 failed: %s", ssh_err(r)); ++ ++ if (BN_num_bits(p) < min || BN_num_bits(p) > max) ++ fatal("GSSGRP_GEX group out of range: %d !< %d !< %d", ++ min, BN_num_bits(p), max); ++ ++ if ((kex->dh = dh_new_group(g, p)) == NULL) ++ fatal("dn_new_group() failed"); ++ p = g = NULL; /* belong to kex->dh now */ ++ ++ if ((r = dh_gen_key(kex->dh, kex->we_need * 8)) != 0) ++ goto out; ++ DH_get0_key(kex->dh, &pub_key, NULL); ++ ++ token_ptr = GSS_C_NO_BUFFER; ++ ++ do { ++ /* Step 2 - call GSS_Init_sec_context() */ ++ debug("Calling gss_init_sec_context"); ++ ++ maj_status = ssh_gssapi_init_ctx(ctxt, ++ kex->gss_deleg_creds, token_ptr, &send_tok, ++ &ret_flags); ++ ++ if (GSS_ERROR(maj_status)) { ++ /* XXX Useles code: Missing send? */ ++ if (send_tok.length != 0) { ++ if ((r = sshpkt_start(ssh, ++ SSH2_MSG_KEXGSS_CONTINUE)) != 0 || ++ (r = sshpkt_put_string(ssh, send_tok.value, ++ send_tok.length)) != 0) ++ fatal("sshpkt failed: %s", ssh_err(r)); ++ } ++ fatal("gss_init_context failed"); ++ } ++ ++ /* If we've got an old receive buffer get rid of it */ ++ if (token_ptr != GSS_C_NO_BUFFER) ++ gss_release_buffer(&min_status, &recv_tok); ++ ++ if (maj_status == GSS_S_COMPLETE) { ++ /* If mutual state flag is not true, kex fails */ ++ if (!(ret_flags & GSS_C_MUTUAL_FLAG)) ++ fatal("Mutual authentication failed"); ++ ++ /* If integ avail flag is not true kex fails */ ++ if (!(ret_flags & GSS_C_INTEG_FLAG)) ++ fatal("Integrity check failed"); ++ } ++ ++ /* ++ * If we have data to send, then the last message that we ++ * received cannot have been a 'complete'. ++ */ ++ if (send_tok.length != 0) { ++ if (first) { ++ if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_INIT)) != 0 || ++ (r = sshpkt_put_string(ssh, send_tok.value, ++ send_tok.length)) != 0 || ++ (r = sshpkt_put_bignum2(ssh, pub_key)) != 0) ++ fatal("sshpkt failed: %s", ssh_err(r)); ++ first = 0; ++ } else { ++ if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_CONTINUE)) != 0 || ++ (r = sshpkt_put_string(ssh,send_tok.value, ++ send_tok.length)) != 0) ++ fatal("sshpkt failed: %s", ssh_err(r)); ++ } ++ if ((r = sshpkt_send(ssh)) != 0) ++ fatal("sshpkt_send failed: %s", ssh_err(r)); ++ gss_release_buffer(&min_status, &send_tok); ++ ++ /* If we've sent them data, they should reply */ ++ do { ++ type = ssh_packet_read(ssh); ++ if (type == SSH2_MSG_KEXGSS_HOSTKEY) { ++ debug("Received KEXGSS_HOSTKEY"); ++ if (server_host_key_blob) ++ fatal("Server host key received more than once"); ++ if ((r = sshpkt_getb_froms(ssh, &server_host_key_blob)) != 0) ++ fatal("sshpkt failed: %s", ssh_err(r)); ++ } ++ } while (type == SSH2_MSG_KEXGSS_HOSTKEY); ++ ++ switch (type) { ++ case SSH2_MSG_KEXGSS_CONTINUE: ++ debug("Received GSSAPI_CONTINUE"); ++ if (maj_status == GSS_S_COMPLETE) ++ fatal("GSSAPI Continue received from server when complete"); ++ if ((r = ssh_gssapi_sshpkt_get_buffer_desc(ssh, ++ &recv_tok)) != 0 || ++ (r = sshpkt_get_end(ssh)) != 0) ++ fatal("sshpkt failed: %s", ssh_err(r)); ++ break; ++ case SSH2_MSG_KEXGSS_COMPLETE: ++ debug("Received GSSAPI_COMPLETE"); ++ if (msg_tok.value != NULL) ++ fatal("Received GSSAPI_COMPLETE twice?"); ++ if ((r = sshpkt_getb_froms(ssh, &server_blob)) != 0 || ++ (r = ssh_gssapi_sshpkt_get_buffer_desc(ssh, ++ &msg_tok)) != 0) ++ fatal("sshpkt failed: %s", ssh_err(r)); ++ ++ /* Is there a token included? */ ++ if ((r = sshpkt_get_u8(ssh, &c)) != 0) ++ fatal("sshpkt failed: %s", ssh_err(r)); ++ if (c) { ++ if ((r = ssh_gssapi_sshpkt_get_buffer_desc( ++ ssh, &recv_tok)) != 0 || ++ (r = sshpkt_get_end(ssh)) != 0) ++ fatal("sshpkt failed: %s", ssh_err(r)); ++ /* If we're already complete - protocol error */ ++ if (maj_status == GSS_S_COMPLETE) ++ sshpkt_disconnect(ssh, "Protocol error: received token when complete"); ++ } else { ++ /* No token included */ ++ if (maj_status != GSS_S_COMPLETE) ++ sshpkt_disconnect(ssh, "Protocol error: did not receive final token"); ++ } ++ break; ++ case SSH2_MSG_KEXGSS_ERROR: ++ debug("Received Error"); ++ if ((r = sshpkt_get_u32(ssh, &maj_status)) != 0 || ++ (r = sshpkt_get_u32(ssh, &min_status)) != 0 || ++ (r = sshpkt_get_string(ssh, &msg, NULL)) != 0 || ++ (r = sshpkt_get_string(ssh, NULL, NULL)) != 0 || /* lang tag */ ++ (r = sshpkt_get_end(ssh)) != 0) ++ fatal("sshpkt failed: %s", ssh_err(r)); ++ fatal("GSSAPI Error: \n%.400s", msg); ++ default: ++ sshpkt_disconnect(ssh, "Protocol error: didn't expect packet type %d", ++ type); ++ } ++ token_ptr = &recv_tok; ++ } else { ++ /* No data, and not complete */ ++ if (maj_status != GSS_S_COMPLETE) ++ fatal("Not complete, and no token output"); ++ } ++ } while (maj_status & GSS_S_CONTINUE_NEEDED); ++ ++ /* ++ * We _must_ have received a COMPLETE message in reply from the ++ * server, which will have set dh_server_pub and msg_tok ++ */ ++ ++ if (type != SSH2_MSG_KEXGSS_COMPLETE) ++ fatal("Didn't receive a SSH2_MSG_KEXGSS_COMPLETE when I expected it"); ++ ++ /* 7. C verifies that the key Q_S is valid */ ++ /* 8. C computes shared secret */ ++ if ((buf = sshbuf_new()) == NULL || ++ (r = sshbuf_put_stringb(buf, server_blob)) != 0 || ++ (r = sshbuf_get_bignum2(buf, &dh_server_pub)) != 0) ++ goto out; ++ sshbuf_free(buf); ++ buf = NULL; ++ ++ if ((shared_secret = sshbuf_new()) == NULL) { ++ r = SSH_ERR_ALLOC_FAIL; ++ goto out; ++ } ++ ++ if ((r = kex_dh_compute_key(kex, dh_server_pub, shared_secret)) != 0) ++ goto out; ++ if ((empty = sshbuf_new()) == NULL) { ++ r = SSH_ERR_ALLOC_FAIL; ++ goto out; ++ } ++ ++ DH_get0_pqg(kex->dh, &dh_p, NULL, &dh_g); ++ hashlen = sizeof(hash); ++ if ((r = kexgex_hash( ++ kex->hash_alg, ++ kex->client_version, ++ kex->server_version, ++ kex->my, ++ kex->peer, ++ (server_host_key_blob ? server_host_key_blob : empty), ++ kex->min, kex->nbits, kex->max, ++ dh_p, dh_g, ++ pub_key, ++ dh_server_pub, ++ sshbuf_ptr(shared_secret), sshbuf_len(shared_secret), ++ hash, &hashlen)) != 0) ++ fatal("Failed to calculate hash: %s", ssh_err(r)); ++ ++ gssbuf.value = hash; ++ gssbuf.length = hashlen; ++ ++ /* Verify that the hash matches the MIC we just got. */ ++ if (GSS_ERROR(ssh_gssapi_checkmic(ctxt, &gssbuf, &msg_tok))) ++ sshpkt_disconnect(ssh, "Hash's MIC didn't verify"); ++ ++ gss_release_buffer(&min_status, &msg_tok); ++ ++ if (kex->gss_deleg_creds) ++ ssh_gssapi_credentials_updated(ctxt); ++ ++ if (gss_kex_context == NULL) ++ gss_kex_context = ctxt; ++ else ++ ssh_gssapi_delete_ctx(&ctxt); ++ ++ /* Finally derive the keys and send them */ ++ if ((r = kex_derive_keys(ssh, hash, hashlen, shared_secret)) == 0) ++ r = kex_send_newkeys(ssh); ++out: ++ sshbuf_free(buf); ++ sshbuf_free(server_blob); ++ sshbuf_free(empty); ++ explicit_bzero(hash, sizeof(hash)); ++ DH_free(kex->dh); ++ kex->dh = NULL; ++ BN_clear_free(dh_server_pub); ++ sshbuf_free(shared_secret); ++ sshbuf_free(server_host_key_blob); ++ return r; ++} ++#endif /* defined(GSSAPI) && defined(WITH_OPENSSL) */ +diff --git a/kexgsss.c b/kexgsss.c +new file mode 100644 +index 000000000..a2c02148b +--- /dev/null ++++ b/kexgsss.c +@@ -0,0 +1,474 @@ ++/* ++ * Copyright (c) 2001-2009 Simon Wilkinson. 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" ++ ++#if defined(GSSAPI) && defined(WITH_OPENSSL) ++ ++#include <string.h> ++ ++#include <openssl/crypto.h> ++#include <openssl/bn.h> ++ ++#include "xmalloc.h" ++#include "sshbuf.h" ++#include "ssh2.h" ++#include "sshkey.h" ++#include "cipher.h" ++#include "kex.h" ++#include "log.h" ++#include "packet.h" ++#include "dh.h" ++#include "ssh-gss.h" ++#include "monitor_wrap.h" ++#include "misc.h" /* servconf.h needs misc.h for struct ForwardOptions */ ++#include "servconf.h" ++#include "ssh-gss.h" ++#include "digest.h" ++#include "ssherr.h" ++ ++extern ServerOptions options; ++ ++int ++kexgss_server(struct ssh *ssh) ++{ ++ struct kex *kex = ssh->kex; ++ OM_uint32 maj_status, min_status; ++ ++ /* ++ * Some GSSAPI implementations use the input value of ret_flags (an ++ * output variable) as a means of triggering mechanism specific ++ * features. Initializing it to zero avoids inadvertently ++ * activating this non-standard behaviour. ++ */ ++ ++ OM_uint32 ret_flags = 0; ++ gss_buffer_desc gssbuf, recv_tok, msg_tok; ++ gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; ++ Gssctxt *ctxt = NULL; ++ struct sshbuf *shared_secret = NULL; ++ struct sshbuf *client_pubkey = NULL; ++ struct sshbuf *server_pubkey = NULL; ++ struct sshbuf *empty = sshbuf_new(); ++ int type = 0; ++ gss_OID oid; ++ char *mechs; ++ u_char hash[SSH_DIGEST_MAX_LENGTH]; ++ size_t hashlen; ++ int r; ++ ++ /* Initialise GSSAPI */ ++ ++ /* If we're rekeying, privsep means that some of the private structures ++ * in the GSSAPI code are no longer available. This kludges them back ++ * into life ++ */ ++ if (!ssh_gssapi_oid_table_ok()) { ++ mechs = ssh_gssapi_server_mechanisms(); ++ free(mechs); ++ } ++ ++ debug2_f("Identifying %s", kex->name); ++ oid = ssh_gssapi_id_kex(NULL, kex->name, kex->kex_type); ++ if (oid == GSS_C_NO_OID) ++ fatal("Unknown gssapi mechanism"); ++ ++ debug2_f("Acquiring credentials"); ++ ++ if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, oid)))) ++ fatal("Unable to acquire credentials for the server"); ++ ++ do { ++ debug("Wait SSH2_MSG_KEXGSS_INIT"); ++ type = ssh_packet_read(ssh); ++ switch(type) { ++ case SSH2_MSG_KEXGSS_INIT: ++ if (client_pubkey != NULL) ++ fatal("Received KEXGSS_INIT after initialising"); ++ if ((r = ssh_gssapi_sshpkt_get_buffer_desc(ssh, ++ &recv_tok)) != 0 || ++ (r = sshpkt_getb_froms(ssh, &client_pubkey)) != 0 || ++ (r = sshpkt_get_end(ssh)) != 0) ++ fatal("sshpkt failed: %s", ssh_err(r)); ++ ++ switch (kex->kex_type) { ++ case KEX_GSS_GRP1_SHA1: ++ case KEX_GSS_GRP14_SHA1: ++ case KEX_GSS_GRP14_SHA256: ++ case KEX_GSS_GRP16_SHA512: ++ r = kex_dh_enc(kex, client_pubkey, &server_pubkey, ++ &shared_secret); ++ break; ++ case KEX_GSS_NISTP256_SHA256: ++ r = kex_ecdh_enc(kex, client_pubkey, &server_pubkey, ++ &shared_secret); ++ break; ++ case KEX_GSS_C25519_SHA256: ++ r = kex_c25519_enc(kex, client_pubkey, &server_pubkey, ++ &shared_secret); ++ break; ++ default: ++ fatal_f("Unexpected KEX type %d", kex->kex_type); ++ } ++ if (r != 0) ++ goto out; ++ ++ /* Send SSH_MSG_KEXGSS_HOSTKEY here, if we want */ ++ break; ++ case SSH2_MSG_KEXGSS_CONTINUE: ++ if ((r = ssh_gssapi_sshpkt_get_buffer_desc(ssh, ++ &recv_tok)) != 0 || ++ (r = sshpkt_get_end(ssh)) != 0) ++ fatal("sshpkt failed: %s", ssh_err(r)); ++ break; ++ default: ++ sshpkt_disconnect(ssh, ++ "Protocol error: didn't expect packet type %d", ++ type); ++ } ++ ++ maj_status = PRIVSEP(ssh_gssapi_accept_ctx(ctxt, &recv_tok, ++ &send_tok, &ret_flags)); ++ ++ gss_release_buffer(&min_status, &recv_tok); ++ ++ if (maj_status != GSS_S_COMPLETE && send_tok.length == 0) ++ fatal("Zero length token output when incomplete"); ++ ++ if (client_pubkey == NULL) ++ fatal("No client public key"); ++ ++ if (maj_status & GSS_S_CONTINUE_NEEDED) { ++ debug("Sending GSSAPI_CONTINUE"); ++ if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_CONTINUE)) != 0 || ++ (r = sshpkt_put_string(ssh, send_tok.value, send_tok.length)) != 0 || ++ (r = sshpkt_send(ssh)) != 0) ++ fatal("sshpkt failed: %s", ssh_err(r)); ++ gss_release_buffer(&min_status, &send_tok); ++ } ++ } while (maj_status & GSS_S_CONTINUE_NEEDED); ++ ++ if (GSS_ERROR(maj_status)) { ++ if (send_tok.length > 0) { ++ if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_CONTINUE)) != 0 || ++ (r = sshpkt_put_string(ssh, send_tok.value, send_tok.length)) != 0 || ++ (r = sshpkt_send(ssh)) != 0) ++ fatal("sshpkt failed: %s", ssh_err(r)); ++ } ++ fatal("accept_ctx died"); ++ } ++ ++ if (!(ret_flags & GSS_C_MUTUAL_FLAG)) ++ fatal("Mutual Authentication flag wasn't set"); ++ ++ if (!(ret_flags & GSS_C_INTEG_FLAG)) ++ fatal("Integrity flag wasn't set"); ++ ++ hashlen = sizeof(hash); ++ if ((r = kex_gen_hash( ++ kex->hash_alg, ++ kex->client_version, ++ kex->server_version, ++ kex->peer, ++ kex->my, ++ empty, ++ client_pubkey, ++ server_pubkey, ++ shared_secret, ++ hash, &hashlen)) != 0) ++ goto out; ++ ++ gssbuf.value = hash; ++ gssbuf.length = hashlen; ++ ++ if (GSS_ERROR(PRIVSEP(ssh_gssapi_sign(ctxt, &gssbuf, &msg_tok)))) ++ fatal("Couldn't get MIC"); ++ ++ if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_COMPLETE)) != 0 || ++ (r = sshpkt_put_stringb(ssh, server_pubkey)) != 0 || ++ (r = sshpkt_put_string(ssh, msg_tok.value, msg_tok.length)) != 0) ++ fatal("sshpkt failed: %s", ssh_err(r)); ++ ++ if (send_tok.length != 0) { ++ if ((r = sshpkt_put_u8(ssh, 1)) != 0 || /* true */ ++ (r = sshpkt_put_string(ssh, send_tok.value, send_tok.length)) != 0) ++ fatal("sshpkt failed: %s", ssh_err(r)); ++ } else { ++ if ((r = sshpkt_put_u8(ssh, 0)) != 0) /* false */ ++ fatal("sshpkt failed: %s", ssh_err(r)); ++ } ++ if ((r = sshpkt_send(ssh)) != 0) ++ fatal("sshpkt_send failed: %s", ssh_err(r)); ++ ++ gss_release_buffer(&min_status, &send_tok); ++ gss_release_buffer(&min_status, &msg_tok); ++ ++ if (gss_kex_context == NULL) ++ gss_kex_context = ctxt; ++ else ++ ssh_gssapi_delete_ctx(&ctxt); ++ ++ if ((r = kex_derive_keys(ssh, hash, hashlen, shared_secret)) == 0) ++ r = kex_send_newkeys(ssh); ++ ++ /* If this was a rekey, then save out any delegated credentials we ++ * just exchanged. */ ++ if (options.gss_store_rekey) ++ ssh_gssapi_rekey_creds(); ++out: ++ sshbuf_free(empty); ++ explicit_bzero(hash, sizeof(hash)); ++ sshbuf_free(shared_secret); ++ sshbuf_free(client_pubkey); ++ sshbuf_free(server_pubkey); ++ return r; ++} ++ ++int ++kexgssgex_server(struct ssh *ssh) ++{ ++ struct kex *kex = ssh->kex; ++ OM_uint32 maj_status, min_status; ++ ++ /* ++ * Some GSSAPI implementations use the input value of ret_flags (an ++ * output variable) as a means of triggering mechanism specific ++ * features. Initializing it to zero avoids inadvertently ++ * activating this non-standard behaviour. ++ */ ++ ++ OM_uint32 ret_flags = 0; ++ gss_buffer_desc gssbuf, recv_tok, msg_tok; ++ gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; ++ Gssctxt *ctxt = NULL; ++ struct sshbuf *shared_secret = NULL; ++ int type = 0; ++ gss_OID oid; ++ char *mechs; ++ u_char hash[SSH_DIGEST_MAX_LENGTH]; ++ size_t hashlen; ++ BIGNUM *dh_client_pub = NULL; ++ const BIGNUM *pub_key, *dh_p, *dh_g; ++ int min = -1, max = -1, nbits = -1; ++ int cmin = -1, cmax = -1; /* client proposal */ ++ struct sshbuf *empty = sshbuf_new(); ++ int r; ++ ++ /* Initialise GSSAPI */ ++ ++ /* If we're rekeying, privsep means that some of the private structures ++ * in the GSSAPI code are no longer available. This kludges them back ++ * into life ++ */ ++ if (!ssh_gssapi_oid_table_ok()) ++ if ((mechs = ssh_gssapi_server_mechanisms())) ++ free(mechs); ++ ++ debug2_f("Identifying %s", kex->name); ++ oid = ssh_gssapi_id_kex(NULL, kex->name, kex->kex_type); ++ if (oid == GSS_C_NO_OID) ++ fatal("Unknown gssapi mechanism"); ++ ++ debug2_f("Acquiring credentials"); ++ ++ if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, oid)))) ++ fatal("Unable to acquire credentials for the server"); ++ ++ /* 5. S generates an ephemeral key pair (do the allocations early) */ ++ debug("Doing group exchange"); ++ ssh_packet_read_expect(ssh, SSH2_MSG_KEXGSS_GROUPREQ); ++ /* store client proposal to provide valid signature */ ++ if ((r = sshpkt_get_u32(ssh, &cmin)) != 0 || ++ (r = sshpkt_get_u32(ssh, &nbits)) != 0 || ++ (r = sshpkt_get_u32(ssh, &cmax)) != 0 || ++ (r = sshpkt_get_end(ssh)) != 0) ++ fatal("sshpkt failed: %s", ssh_err(r)); ++ kex->nbits = nbits; ++ kex->min = cmin; ++ kex->max = cmax; ++ min = MAX(DH_GRP_MIN, cmin); ++ max = MIN(DH_GRP_MAX, cmax); ++ nbits = MAXIMUM(DH_GRP_MIN, nbits); ++ nbits = MINIMUM(DH_GRP_MAX, nbits); ++ if (max < min || nbits < min || max < nbits) ++ fatal("GSS_GEX, bad parameters: %d !< %d !< %d", ++ min, nbits, max); ++ kex->dh = PRIVSEP(choose_dh(min, nbits, max)); ++ if (kex->dh == NULL) { ++ sshpkt_disconnect(ssh, "Protocol error: no matching group found"); ++ fatal("Protocol error: no matching group found"); ++ } ++ ++ DH_get0_pqg(kex->dh, &dh_p, NULL, &dh_g); ++ if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_GROUP)) != 0 || ++ (r = sshpkt_put_bignum2(ssh, dh_p)) != 0 || ++ (r = sshpkt_put_bignum2(ssh, dh_g)) != 0 || ++ (r = sshpkt_send(ssh)) != 0) ++ fatal("sshpkt failed: %s", ssh_err(r)); ++ ++ if ((r = ssh_packet_write_wait(ssh)) != 0) ++ fatal("ssh_packet_write_wait: %s", ssh_err(r)); ++ ++ /* Compute our exchange value in parallel with the client */ ++ if ((r = dh_gen_key(kex->dh, kex->we_need * 8)) != 0) ++ goto out; ++ ++ do { ++ debug("Wait SSH2_MSG_GSSAPI_INIT"); ++ type = ssh_packet_read(ssh); ++ switch(type) { ++ case SSH2_MSG_KEXGSS_INIT: ++ if (dh_client_pub != NULL) ++ fatal("Received KEXGSS_INIT after initialising"); ++ if ((r = ssh_gssapi_sshpkt_get_buffer_desc(ssh, ++ &recv_tok)) != 0 || ++ (r = sshpkt_get_bignum2(ssh, &dh_client_pub)) != 0 || ++ (r = sshpkt_get_end(ssh)) != 0) ++ fatal("sshpkt failed: %s", ssh_err(r)); ++ ++ /* Send SSH_MSG_KEXGSS_HOSTKEY here, if we want */ ++ break; ++ case SSH2_MSG_KEXGSS_CONTINUE: ++ if ((r = ssh_gssapi_sshpkt_get_buffer_desc(ssh, ++ &recv_tok)) != 0 || ++ (r = sshpkt_get_end(ssh)) != 0) ++ fatal("sshpkt failed: %s", ssh_err(r)); ++ break; ++ default: ++ sshpkt_disconnect(ssh, ++ "Protocol error: didn't expect packet type %d", ++ type); ++ } ++ ++ maj_status = PRIVSEP(ssh_gssapi_accept_ctx(ctxt, &recv_tok, ++ &send_tok, &ret_flags)); ++ ++ gss_release_buffer(&min_status, &recv_tok); ++ ++ if (maj_status != GSS_S_COMPLETE && send_tok.length == 0) ++ fatal("Zero length token output when incomplete"); ++ ++ if (dh_client_pub == NULL) ++ fatal("No client public key"); ++ ++ if (maj_status & GSS_S_CONTINUE_NEEDED) { ++ debug("Sending GSSAPI_CONTINUE"); ++ if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_CONTINUE)) != 0 || ++ (r = sshpkt_put_string(ssh, send_tok.value, send_tok.length)) != 0 || ++ (r = sshpkt_send(ssh)) != 0) ++ fatal("sshpkt failed: %s", ssh_err(r)); ++ gss_release_buffer(&min_status, &send_tok); ++ } ++ } while (maj_status & GSS_S_CONTINUE_NEEDED); ++ ++ if (GSS_ERROR(maj_status)) { ++ if (send_tok.length > 0) { ++ if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_CONTINUE)) != 0 || ++ (r = sshpkt_put_string(ssh, send_tok.value, send_tok.length)) != 0 || ++ (r = sshpkt_send(ssh)) != 0) ++ fatal("sshpkt failed: %s", ssh_err(r)); ++ } ++ fatal("accept_ctx died"); ++ } ++ ++ if (!(ret_flags & GSS_C_MUTUAL_FLAG)) ++ fatal("Mutual Authentication flag wasn't set"); ++ ++ if (!(ret_flags & GSS_C_INTEG_FLAG)) ++ fatal("Integrity flag wasn't set"); ++ ++ /* calculate shared secret */ ++ if ((shared_secret = sshbuf_new()) == NULL) { ++ r = SSH_ERR_ALLOC_FAIL; ++ goto out; ++ } ++ if ((r = kex_dh_compute_key(kex, dh_client_pub, shared_secret)) != 0) ++ goto out; ++ ++ DH_get0_key(kex->dh, &pub_key, NULL); ++ DH_get0_pqg(kex->dh, &dh_p, NULL, &dh_g); ++ hashlen = sizeof(hash); ++ if ((r = kexgex_hash( ++ kex->hash_alg, ++ kex->client_version, ++ kex->server_version, ++ kex->peer, ++ kex->my, ++ empty, ++ cmin, nbits, cmax, ++ dh_p, dh_g, ++ dh_client_pub, ++ pub_key, ++ sshbuf_ptr(shared_secret), sshbuf_len(shared_secret), ++ hash, &hashlen)) != 0) ++ fatal("kexgex_hash failed: %s", ssh_err(r)); ++ ++ gssbuf.value = hash; ++ gssbuf.length = hashlen; ++ ++ if (GSS_ERROR(PRIVSEP(ssh_gssapi_sign(ctxt, &gssbuf, &msg_tok)))) ++ fatal("Couldn't get MIC"); ++ ++ if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_COMPLETE)) != 0 || ++ (r = sshpkt_put_bignum2(ssh, pub_key)) != 0 || ++ (r = sshpkt_put_string(ssh, msg_tok.value, msg_tok.length)) != 0) ++ fatal("sshpkt failed: %s", ssh_err(r)); ++ ++ if (send_tok.length != 0) { ++ if ((r = sshpkt_put_u8(ssh, 1)) != 0 || /* true */ ++ (r = sshpkt_put_string(ssh, send_tok.value, send_tok.length)) != 0) ++ fatal("sshpkt failed: %s", ssh_err(r)); ++ } else { ++ if ((r = sshpkt_put_u8(ssh, 0)) != 0) /* false */ ++ fatal("sshpkt failed: %s", ssh_err(r)); ++ } ++ if ((r = sshpkt_send(ssh)) != 0) ++ fatal("sshpkt failed: %s", ssh_err(r)); ++ ++ gss_release_buffer(&min_status, &send_tok); ++ gss_release_buffer(&min_status, &msg_tok); ++ ++ if (gss_kex_context == NULL) ++ gss_kex_context = ctxt; ++ else ++ ssh_gssapi_delete_ctx(&ctxt); ++ ++ /* Finally derive the keys and send them */ ++ if ((r = kex_derive_keys(ssh, hash, hashlen, shared_secret)) == 0) ++ r = kex_send_newkeys(ssh); ++ ++ /* If this was a rekey, then save out any delegated credentials we ++ * just exchanged. */ ++ if (options.gss_store_rekey) ++ ssh_gssapi_rekey_creds(); ++out: ++ sshbuf_free(empty); ++ explicit_bzero(hash, sizeof(hash)); ++ DH_free(kex->dh); ++ kex->dh = NULL; ++ BN_clear_free(dh_client_pub); ++ sshbuf_free(shared_secret); ++ return r; ++} ++#endif /* defined(GSSAPI) && defined(WITH_OPENSSL) */ +diff --git a/monitor.c b/monitor.c +index 91e0e6245..5f7df9539 100644 +--- a/monitor.c ++++ b/monitor.c +@@ -145,6 +145,8 @@ int mm_answer_gss_setup_ctx(struct ssh *, int, struct sshbuf *); + int mm_answer_gss_accept_ctx(struct ssh *, int, struct sshbuf *); + int mm_answer_gss_userok(struct ssh *, int, struct sshbuf *); + int mm_answer_gss_checkmic(struct ssh *, int, struct sshbuf *); ++int mm_answer_gss_sign(struct ssh *, int, struct sshbuf *); ++int mm_answer_gss_updatecreds(struct ssh *, int, struct sshbuf *); + #endif + + #ifdef SSH_AUDIT_EVENTS +@@ -217,11 +219,18 @@ struct mon_table mon_dispatch_proto20[] = { + {MONITOR_REQ_GSSSTEP, 0, mm_answer_gss_accept_ctx}, + {MONITOR_REQ_GSSUSEROK, MON_ONCE|MON_AUTHDECIDE, mm_answer_gss_userok}, + {MONITOR_REQ_GSSCHECKMIC, MON_ONCE, mm_answer_gss_checkmic}, ++ {MONITOR_REQ_GSSSIGN, MON_ONCE, mm_answer_gss_sign}, + #endif + {0, 0, NULL} + }; + + struct mon_table mon_dispatch_postauth20[] = { ++#ifdef GSSAPI ++ {MONITOR_REQ_GSSSETUP, 0, mm_answer_gss_setup_ctx}, ++ {MONITOR_REQ_GSSSTEP, 0, mm_answer_gss_accept_ctx}, ++ {MONITOR_REQ_GSSSIGN, 0, mm_answer_gss_sign}, ++ {MONITOR_REQ_GSSUPCREDS, 0, mm_answer_gss_updatecreds}, ++#endif + #ifdef WITH_OPENSSL + {MONITOR_REQ_MODULI, 0, mm_answer_moduli}, + #endif +@@ -290,6 +299,10 @@ monitor_child_preauth(struct ssh *ssh, struct monitor *pmonitor) + /* Permit requests for moduli and signatures */ + monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1); + monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1); ++#ifdef GSSAPI ++ /* and for the GSSAPI key exchange */ ++ monitor_permit(mon_dispatch, MONITOR_REQ_GSSSETUP, 1); ++#endif + + /* The first few requests do not require asynchronous access */ + while (!authenticated) { +@@ -401,6 +414,10 @@ monitor_child_postauth(struct ssh *ssh, struct monitor *pmonitor) + monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1); + monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1); + monitor_permit(mon_dispatch, MONITOR_REQ_TERM, 1); ++#ifdef GSSAPI ++ /* and for the GSSAPI key exchange */ ++ monitor_permit(mon_dispatch, MONITOR_REQ_GSSSETUP, 1); ++#endif + + if (auth_opts->permit_pty_flag) { + monitor_permit(mon_dispatch, MONITOR_REQ_PTY, 1); +@@ -1744,6 +1761,17 @@ monitor_apply_keystate(struct ssh *ssh, struct monitor *pmonitor) + # ifdef OPENSSL_HAS_ECC + kex->kex[KEX_ECDH_SHA2] = kex_gen_server; + # endif ++# ifdef GSSAPI ++ if (options.gss_keyex) { ++ kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_server; ++ kex->kex[KEX_GSS_GRP14_SHA1] = kexgss_server; ++ kex->kex[KEX_GSS_GRP14_SHA256] = kexgss_server; ++ kex->kex[KEX_GSS_GRP16_SHA512] = kexgss_server; ++ kex->kex[KEX_GSS_GEX_SHA1] = kexgssgex_server; ++ kex->kex[KEX_GSS_NISTP256_SHA256] = kexgss_server; ++ kex->kex[KEX_GSS_C25519_SHA256] = kexgss_server; ++ } ++# endif + #endif /* WITH_OPENSSL */ + kex->kex[KEX_C25519_SHA256] = kex_gen_server; + kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_server; +@@ -1836,8 +1864,8 @@ mm_answer_gss_setup_ctx(struct ssh *ssh, int sock, struct sshbuf *m) + u_char *p; + int r; + +- if (!options.gss_authentication) +- fatal_f("GSSAPI authentication not enabled"); ++ if (!options.gss_authentication && !options.gss_keyex) ++ fatal_f("GSSAPI not enabled"); + + if ((r = sshbuf_get_string(m, &p, &len)) != 0) + fatal_fr(r, "parse"); +@@ -1869,8 +1897,8 @@ mm_answer_gss_accept_ctx(struct ssh *ssh, int sock, struct sshbuf *m) + OM_uint32 flags = 0; /* GSI needs this */ + int r; + +- if (!options.gss_authentication) +- fatal_f("GSSAPI authentication not enabled"); ++ if (!options.gss_authentication && !options.gss_keyex) ++ fatal_f("GSSAPI not enabled"); + + if ((r = ssh_gssapi_get_buffer_desc(m, &in)) != 0) + fatal_fr(r, "ssh_gssapi_get_buffer_desc"); +@@ -1890,6 +1918,7 @@ mm_answer_gss_accept_ctx(struct ssh *ssh, int sock, struct sshbuf *m) + monitor_permit(mon_dispatch, MONITOR_REQ_GSSSTEP, 0); + monitor_permit(mon_dispatch, MONITOR_REQ_GSSUSEROK, 1); + monitor_permit(mon_dispatch, MONITOR_REQ_GSSCHECKMIC, 1); ++ monitor_permit(mon_dispatch, MONITOR_REQ_GSSSIGN, 1); + } + return (0); + } +@@ -1901,8 +1930,8 @@ mm_answer_gss_checkmic(struct ssh *ssh, int sock, struct sshbuf *m) + OM_uint32 ret; + int r; + +- if (!options.gss_authentication) +- fatal_f("GSSAPI authentication not enabled"); ++ if (!options.gss_authentication && !options.gss_keyex) ++ fatal_f("GSSAPI not enabled"); + + if ((r = ssh_gssapi_get_buffer_desc(m, &gssbuf)) != 0 || + (r = ssh_gssapi_get_buffer_desc(m, &mic)) != 0) +@@ -1928,13 +1957,17 @@ mm_answer_gss_checkmic(struct ssh *ssh, int sock, struct sshbuf *m) + int + mm_answer_gss_userok(struct ssh *ssh, int sock, struct sshbuf *m) + { +- int r, authenticated; ++ int r, authenticated, kex; + const char *displayname; + +- if (!options.gss_authentication) +- fatal_f("GSSAPI authentication not enabled"); ++ if (!options.gss_authentication && !options.gss_keyex) ++ fatal_f("GSSAPI not enabled"); + +- authenticated = authctxt->valid && ssh_gssapi_userok(authctxt->user); ++ if ((r = sshbuf_get_u32(m, &kex)) != 0) ++ fatal_fr(r, "buffer error"); ++ ++ authenticated = authctxt->valid && ++ ssh_gssapi_userok(authctxt->user, authctxt->pw, kex); + + sshbuf_reset(m); + if ((r = sshbuf_put_u32(m, authenticated)) != 0) +@@ -1943,7 +1976,11 @@ mm_answer_gss_userok(struct ssh *ssh, int sock, struct sshbuf *m) + debug3_f("sending result %d", authenticated); + mm_request_send(sock, MONITOR_ANS_GSSUSEROK, m); + +- auth_method = "gssapi-with-mic"; ++ if (kex) { ++ auth_method = "gssapi-keyex"; ++ } else { ++ auth_method = "gssapi-with-mic"; ++ } + + if ((displayname = ssh_gssapi_displayname()) != NULL) + auth2_record_info(authctxt, "%s", displayname); +@@ -1951,5 +1988,83 @@ mm_answer_gss_userok(struct ssh *ssh, int sock, struct sshbuf *m) + /* Monitor loop will terminate if authenticated */ + return (authenticated); + } +-#endif /* GSSAPI */ + ++int ++mm_answer_gss_sign(struct ssh *ssh, int socket, struct sshbuf *m) ++{ ++ gss_buffer_desc data; ++ gss_buffer_desc hash = GSS_C_EMPTY_BUFFER; ++ OM_uint32 major, minor; ++ size_t len; ++ u_char *p = NULL; ++ int r; ++ ++ if (!options.gss_authentication && !options.gss_keyex) ++ fatal_f("GSSAPI not enabled"); ++ ++ if ((r = sshbuf_get_string(m, &p, &len)) != 0) ++ fatal_fr(r, "buffer error"); ++ data.value = p; ++ data.length = len; ++ /* Lengths of SHA-1, SHA-256 and SHA-512 hashes that are used */ ++ if (data.length != 20 && data.length != 32 && data.length != 64) ++ fatal_f("data length incorrect: %d", (int) data.length); ++ ++ /* Save the session ID on the first time around */ ++ if (session_id2_len == 0) { ++ session_id2_len = data.length; ++ session_id2 = xmalloc(session_id2_len); ++ memcpy(session_id2, data.value, session_id2_len); ++ } ++ major = ssh_gssapi_sign(gsscontext, &data, &hash); ++ ++ free(data.value); ++ ++ sshbuf_reset(m); ++ ++ if ((r = sshbuf_put_u32(m, major)) != 0 || ++ (r = sshbuf_put_string(m, hash.value, hash.length)) != 0) ++ fatal_fr(r, "buffer error"); ++ ++ mm_request_send(socket, MONITOR_ANS_GSSSIGN, m); ++ ++ gss_release_buffer(&minor, &hash); ++ ++ /* Turn on getpwnam permissions */ ++ monitor_permit(mon_dispatch, MONITOR_REQ_PWNAM, 1); ++ ++ /* And credential updating, for when rekeying */ ++ monitor_permit(mon_dispatch, MONITOR_REQ_GSSUPCREDS, 1); ++ ++ return (0); ++} ++ ++int ++mm_answer_gss_updatecreds(struct ssh *ssh, int socket, struct sshbuf *m) { ++ ssh_gssapi_ccache store; ++ int r, ok; ++ ++ if (!options.gss_authentication && !options.gss_keyex) ++ fatal_f("GSSAPI not enabled"); ++ ++ if ((r = sshbuf_get_string(m, (u_char **)&store.filename, NULL)) != 0 || ++ (r = sshbuf_get_string(m, (u_char **)&store.envvar, NULL)) != 0 || ++ (r = sshbuf_get_string(m, (u_char **)&store.envval, NULL)) != 0) ++ fatal_fr(r, "buffer error"); ++ ++ ok = ssh_gssapi_update_creds(&store); ++ ++ free(store.filename); ++ free(store.envvar); ++ free(store.envval); ++ ++ sshbuf_reset(m); ++ if ((r = sshbuf_put_u32(m, ok)) != 0) ++ fatal_fr(r, "buffer error"); ++ ++ mm_request_send(socket, MONITOR_ANS_GSSUPCREDS, m); ++ ++ return(0); ++} ++ ++#endif /* GSSAPI */ +diff --git a/monitor.h b/monitor.h +index 683e5e071..2b1a2d590 100644 +--- a/monitor.h ++++ b/monitor.h +@@ -63,6 +63,8 @@ enum monitor_reqtype { + MONITOR_REQ_PAM_FREE_CTX = 110, MONITOR_ANS_PAM_FREE_CTX = 111, + MONITOR_REQ_AUDIT_EVENT = 112, MONITOR_REQ_AUDIT_COMMAND = 113, + ++ MONITOR_REQ_GSSSIGN = 150, MONITOR_ANS_GSSSIGN = 151, ++ MONITOR_REQ_GSSUPCREDS = 152, MONITOR_ANS_GSSUPCREDS = 153, + }; + + struct ssh; +diff --git a/monitor_wrap.c b/monitor_wrap.c +index 8e379a15c..a4b66c56f 100644 +--- a/monitor_wrap.c ++++ b/monitor_wrap.c +@@ -1000,13 +1000,15 @@ mm_ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic) + } + + int +-mm_ssh_gssapi_userok(char *user) ++mm_ssh_gssapi_userok(char *user, struct passwd *pw, int kex) + { + struct sshbuf *m; + int r, authenticated = 0; + + if ((m = sshbuf_new()) == NULL) + fatal_f("sshbuf_new failed"); ++ if ((r = sshbuf_put_u32(m, kex)) != 0) ++ fatal_fr(r, "buffer error"); + + mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_GSSUSEROK, m); + mm_request_receive_expect(pmonitor->m_recvfd, +@@ -1019,4 +1021,57 @@ mm_ssh_gssapi_userok(char *user) + debug3_f("user %sauthenticated", authenticated ? "" : "not "); + return (authenticated); + } ++ ++OM_uint32 ++mm_ssh_gssapi_sign(Gssctxt *ctx, gss_buffer_desc *data, gss_buffer_desc *hash) ++{ ++ struct sshbuf *m; ++ OM_uint32 major; ++ int r; ++ ++ if ((m = sshbuf_new()) == NULL) ++ fatal_f("sshbuf_new failed"); ++ if ((r = sshbuf_put_string(m, data->value, data->length)) != 0) ++ fatal_fr(r, "buffer error"); ++ ++ mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_GSSSIGN, m); ++ mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_GSSSIGN, m); ++ ++ if ((r = sshbuf_get_u32(m, &major)) != 0 || ++ (r = ssh_gssapi_get_buffer_desc(m, hash)) != 0) ++ fatal_fr(r, "buffer error"); ++ ++ sshbuf_free(m); ++ ++ return (major); ++} ++ ++int ++mm_ssh_gssapi_update_creds(ssh_gssapi_ccache *store) ++{ ++ struct sshbuf *m; ++ int r, ok; ++ ++ if ((m = sshbuf_new()) == NULL) ++ fatal_f("sshbuf_new failed"); ++ ++ if ((r = sshbuf_put_cstring(m, ++ store->filename ? store->filename : "")) != 0 || ++ (r = sshbuf_put_cstring(m, ++ store->envvar ? store->envvar : "")) != 0 || ++ (r = sshbuf_put_cstring(m, ++ store->envval ? store->envval : "")) != 0) ++ fatal_fr(r, "buffer error"); ++ ++ mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_GSSUPCREDS, m); ++ mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_GSSUPCREDS, m); ++ ++ if ((r = sshbuf_get_u32(m, &ok)) != 0) ++ fatal_fr(r, "buffer error"); ++ ++ sshbuf_free(m); ++ ++ return (ok); ++} ++ + #endif /* GSSAPI */ +diff --git a/monitor_wrap.h b/monitor_wrap.h +index 0df49c25b..830fdb308 100644 +--- a/monitor_wrap.h ++++ b/monitor_wrap.h +@@ -65,8 +65,10 @@ int mm_sshkey_verify(const struct sshkey *, const u_char *, size_t, + OM_uint32 mm_ssh_gssapi_server_ctx(Gssctxt **, gss_OID); + OM_uint32 mm_ssh_gssapi_accept_ctx(Gssctxt *, + gss_buffer_desc *, gss_buffer_desc *, OM_uint32 *); +-int mm_ssh_gssapi_userok(char *user); ++int mm_ssh_gssapi_userok(char *user, struct passwd *, int kex); + OM_uint32 mm_ssh_gssapi_checkmic(Gssctxt *, gss_buffer_t, gss_buffer_t); ++OM_uint32 mm_ssh_gssapi_sign(Gssctxt *, gss_buffer_t, gss_buffer_t); ++int mm_ssh_gssapi_update_creds(ssh_gssapi_ccache *); + #endif + + #ifdef USE_PAM +diff --git a/readconf.c b/readconf.c +index cf7949884..55af0115d 100644 +--- a/readconf.c ++++ b/readconf.c +@@ -67,6 +67,7 @@ + #include "uidswap.h" + #include "myproposal.h" + #include "digest.h" ++#include "ssh-gss.h" + + /* Format of the configuration file: + +@@ -161,6 +162,8 @@ typedef enum { + oClearAllForwardings, oNoHostAuthenticationForLocalhost, + oEnableSSHKeysign, oRekeyLimit, oVerifyHostKeyDNS, oConnectTimeout, + oAddressFamily, oGssAuthentication, oGssDelegateCreds, ++ oGssTrustDns, oGssKeyEx, oGssClientIdentity, oGssRenewalRekey, ++ oGssServerIdentity, oGssKexAlgorithms, + oServerAliveInterval, oServerAliveCountMax, oIdentitiesOnly, + oSendEnv, oSetEnv, oControlPath, oControlMaster, oControlPersist, + oHashKnownHosts, +@@ -207,10 +210,22 @@ static struct { + /* Sometimes-unsupported options */ + #if defined(GSSAPI) + { "gssapiauthentication", oGssAuthentication }, ++ { "gssapikeyexchange", oGssKeyEx }, + { "gssapidelegatecredentials", oGssDelegateCreds }, ++ { "gssapitrustdns", oGssTrustDns }, ++ { "gssapiclientidentity", oGssClientIdentity }, ++ { "gssapiserveridentity", oGssServerIdentity }, ++ { "gssapirenewalforcesrekey", oGssRenewalRekey }, ++ { "gssapikexalgorithms", oGssKexAlgorithms }, + # else + { "gssapiauthentication", oUnsupported }, ++ { "gssapikeyexchange", oUnsupported }, + { "gssapidelegatecredentials", oUnsupported }, ++ { "gssapitrustdns", oUnsupported }, ++ { "gssapiclientidentity", oUnsupported }, ++ { "gssapiserveridentity", oUnsupported }, ++ { "gssapirenewalforcesrekey", oUnsupported }, ++ { "gssapikexalgorithms", oUnsupported }, + #endif + #ifdef ENABLE_PKCS11 + { "pkcs11provider", oPKCS11Provider }, +@@ -1122,10 +1137,46 @@ parse_time: + intptr = &options->gss_authentication; + goto parse_flag; + ++ case oGssKeyEx: ++ intptr = &options->gss_keyex; ++ goto parse_flag; ++ + case oGssDelegateCreds: + intptr = &options->gss_deleg_creds; + goto parse_flag; + ++ case oGssTrustDns: ++ intptr = &options->gss_trust_dns; ++ goto parse_flag; ++ ++ case oGssClientIdentity: ++ charptr = &options->gss_client_identity; ++ goto parse_string; ++ ++ case oGssServerIdentity: ++ charptr = &options->gss_server_identity; ++ goto parse_string; ++ ++ case oGssRenewalRekey: ++ intptr = &options->gss_renewal_rekey; ++ goto parse_flag; ++ ++ case oGssKexAlgorithms: ++ arg = argv_next(&ac, &av); ++ if (!arg || *arg == '\0') { ++ error("%.200s line %d: Missing argument.", ++ filename, linenum); ++ goto out; ++ } ++ if (!kex_gss_names_valid(arg)) { ++ error("%.200s line %d: Bad GSSAPI KexAlgorithms '%s'.", ++ filename, linenum, arg ? arg : "<NONE>"); ++ goto out; ++ } ++ if (*activep && options->gss_kex_algorithms == NULL) ++ options->gss_kex_algorithms = xstrdup(arg); ++ break; ++ + case oBatchMode: + intptr = &options->batch_mode; + goto parse_flag; +@@ -2343,7 +2394,13 @@ initialize_options(Options * options) + options->fwd_opts.streamlocal_bind_unlink = -1; + options->pubkey_authentication = -1; + options->gss_authentication = -1; ++ options->gss_keyex = -1; + options->gss_deleg_creds = -1; ++ options->gss_trust_dns = -1; ++ options->gss_renewal_rekey = -1; ++ options->gss_client_identity = NULL; ++ options->gss_server_identity = NULL; ++ options->gss_kex_algorithms = NULL; + options->password_authentication = -1; + options->kbd_interactive_authentication = -1; + options->kbd_interactive_devices = NULL; +@@ -2502,8 +2559,18 @@ fill_default_options(Options * options) + options->pubkey_authentication = SSH_PUBKEY_AUTH_ALL; + if (options->gss_authentication == -1) + options->gss_authentication = 0; ++ if (options->gss_keyex == -1) ++ options->gss_keyex = 0; + if (options->gss_deleg_creds == -1) + options->gss_deleg_creds = 0; ++ if (options->gss_trust_dns == -1) ++ options->gss_trust_dns = 0; ++ if (options->gss_renewal_rekey == -1) ++ options->gss_renewal_rekey = 0; ++#ifdef GSSAPI ++ if (options->gss_kex_algorithms == NULL) ++ options->gss_kex_algorithms = strdup(GSS_KEX_DEFAULT_KEX); ++#endif + if (options->password_authentication == -1) + options->password_authentication = 1; + if (options->kbd_interactive_authentication == -1) +@@ -3301,7 +3368,14 @@ dump_client_config(Options *o, const char *host) + dump_cfg_fmtint(oGatewayPorts, o->fwd_opts.gateway_ports); + #ifdef GSSAPI + dump_cfg_fmtint(oGssAuthentication, o->gss_authentication); ++ dump_cfg_fmtint(oGssKeyEx, o->gss_keyex); + dump_cfg_fmtint(oGssDelegateCreds, o->gss_deleg_creds); ++ dump_cfg_fmtint(oGssTrustDns, o->gss_trust_dns); ++ dump_cfg_fmtint(oGssRenewalRekey, o->gss_renewal_rekey); ++ dump_cfg_string(oGssClientIdentity, o->gss_client_identity); ++ dump_cfg_string(oGssServerIdentity, o->gss_server_identity); ++ dump_cfg_string(oGssKexAlgorithms, o->gss_kex_algorithms ? ++ o->gss_kex_algorithms : GSS_KEX_DEFAULT_KEX); + #endif /* GSSAPI */ + dump_cfg_fmtint(oHashKnownHosts, o->hash_known_hosts); + dump_cfg_fmtint(oHostbasedAuthentication, o->hostbased_authentication); +diff --git a/readconf.h b/readconf.h +index 2ce1b4c33..d0eb92362 100644 +--- a/readconf.h ++++ b/readconf.h +@@ -40,7 +40,13 @@ typedef struct { + int pubkey_authentication; /* Try ssh2 pubkey authentication. */ + int hostbased_authentication; /* ssh2's rhosts_rsa */ + int gss_authentication; /* Try GSS authentication */ ++ int gss_keyex; /* Try GSS key exchange */ + int gss_deleg_creds; /* Delegate GSS credentials */ ++ int gss_trust_dns; /* Trust DNS for GSS canonicalization */ ++ int gss_renewal_rekey; /* Credential renewal forces rekey */ ++ char *gss_client_identity; /* Principal to initiate GSSAPI with */ ++ char *gss_server_identity; /* GSSAPI target principal */ ++ char *gss_kex_algorithms; /* GSSAPI kex methods to be offered by client. */ + int password_authentication; /* Try password + * authentication. */ + int kbd_interactive_authentication; /* Try keyboard-interactive auth. */ +diff --git a/servconf.c b/servconf.c +index 2e039da8b..940de9e15 100644 +--- a/servconf.c ++++ b/servconf.c +@@ -70,6 +70,7 @@ + #include "auth.h" + #include "myproposal.h" + #include "digest.h" ++#include "ssh-gss.h" + + static void add_listen_addr(ServerOptions *, const char *, + const char *, int); +@@ -136,8 +137,11 @@ initialize_server_options(ServerOptions *options) + options->kerberos_ticket_cleanup = -1; + options->kerberos_get_afs_token = -1; + options->gss_authentication=-1; ++ options->gss_keyex = -1; + options->gss_cleanup_creds = -1; + options->gss_strict_acceptor = -1; ++ options->gss_store_rekey = -1; ++ options->gss_kex_algorithms = NULL; + options->password_authentication = -1; + options->kbd_interactive_authentication = -1; + options->permit_empty_passwd = -1; +@@ -360,10 +364,18 @@ fill_default_server_options(ServerOptions *options) + options->kerberos_get_afs_token = 0; + if (options->gss_authentication == -1) + options->gss_authentication = 0; ++ if (options->gss_keyex == -1) ++ options->gss_keyex = 0; + if (options->gss_cleanup_creds == -1) + options->gss_cleanup_creds = 1; + if (options->gss_strict_acceptor == -1) + options->gss_strict_acceptor = 1; ++ if (options->gss_store_rekey == -1) ++ options->gss_store_rekey = 0; ++#ifdef GSSAPI ++ if (options->gss_kex_algorithms == NULL) ++ options->gss_kex_algorithms = strdup(GSS_KEX_DEFAULT_KEX); ++#endif + if (options->password_authentication == -1) + options->password_authentication = 1; + if (options->kbd_interactive_authentication == -1) +@@ -520,6 +532,7 @@ typedef enum { + sHostKeyAlgorithms, sPerSourceMaxStartups, sPerSourceNetBlockSize, + sClientAliveInterval, sClientAliveCountMax, sAuthorizedKeysFile, + sGssAuthentication, sGssCleanupCreds, sGssStrictAcceptor, ++ sGssKeyEx, sGssKexAlgorithms, sGssStoreRekey, + sAcceptEnv, sSetEnv, sPermitTunnel, + sMatch, sPermitOpen, sPermitListen, sForceCommand, sChrootDirectory, + sUsePrivilegeSeparation, sAllowAgentForwarding, +@@ -602,12 +615,22 @@ static struct { + #ifdef GSSAPI + { "gssapiauthentication", sGssAuthentication, SSHCFG_ALL }, + { "gssapicleanupcredentials", sGssCleanupCreds, SSHCFG_GLOBAL }, ++ { "gssapicleanupcreds", sGssCleanupCreds, SSHCFG_GLOBAL }, + { "gssapistrictacceptorcheck", sGssStrictAcceptor, SSHCFG_GLOBAL }, ++ { "gssapikeyexchange", sGssKeyEx, SSHCFG_GLOBAL }, ++ { "gssapistorecredentialsonrekey", sGssStoreRekey, SSHCFG_GLOBAL }, ++ { "gssapikexalgorithms", sGssKexAlgorithms, SSHCFG_GLOBAL }, + #else + { "gssapiauthentication", sUnsupported, SSHCFG_ALL }, + { "gssapicleanupcredentials", sUnsupported, SSHCFG_GLOBAL }, ++ { "gssapicleanupcreds", sUnsupported, SSHCFG_GLOBAL }, + { "gssapistrictacceptorcheck", sUnsupported, SSHCFG_GLOBAL }, ++ { "gssapikeyexchange", sUnsupported, SSHCFG_GLOBAL }, ++ { "gssapistorecredentialsonrekey", sUnsupported, SSHCFG_GLOBAL }, ++ { "gssapikexalgorithms", sUnsupported, SSHCFG_GLOBAL }, + #endif ++ { "gssusesessionccache", sUnsupported, SSHCFG_GLOBAL }, ++ { "gssapiusesessioncredcache", sUnsupported, SSHCFG_GLOBAL }, + { "passwordauthentication", sPasswordAuthentication, SSHCFG_ALL }, + { "kbdinteractiveauthentication", sKbdInteractiveAuthentication, SSHCFG_ALL }, + { "challengeresponseauthentication", sKbdInteractiveAuthentication, SSHCFG_ALL }, /* alias */ +@@ -1644,6 +1667,10 @@ process_server_config_line_depth(ServerOptions *options, char *line, + intptr = &options->gss_authentication; + goto parse_flag; + ++ case sGssKeyEx: ++ intptr = &options->gss_keyex; ++ goto parse_flag; ++ + case sGssCleanupCreds: + intptr = &options->gss_cleanup_creds; + goto parse_flag; +@@ -1652,6 +1679,22 @@ process_server_config_line_depth(ServerOptions *options, char *line, + intptr = &options->gss_strict_acceptor; + goto parse_flag; + ++ case sGssStoreRekey: ++ intptr = &options->gss_store_rekey; ++ goto parse_flag; ++ ++ case sGssKexAlgorithms: ++ arg = argv_next(&ac, &av); ++ if (!arg || *arg == '\0') ++ fatal("%.200s line %d: Missing argument.", ++ filename, linenum); ++ if (!kex_gss_names_valid(arg)) ++ fatal("%.200s line %d: Bad GSSAPI KexAlgorithms '%s'.", ++ filename, linenum, arg ? arg : "<NONE>"); ++ if (*activep && options->gss_kex_algorithms == NULL) ++ options->gss_kex_algorithms = xstrdup(arg); ++ break; ++ + case sPasswordAuthentication: + intptr = &options->password_authentication; + goto parse_flag; +@@ -3018,6 +3061,10 @@ dump_config(ServerOptions *o) + #ifdef GSSAPI + dump_cfg_fmtint(sGssAuthentication, o->gss_authentication); + dump_cfg_fmtint(sGssCleanupCreds, o->gss_cleanup_creds); ++ dump_cfg_fmtint(sGssKeyEx, o->gss_keyex); ++ dump_cfg_fmtint(sGssStrictAcceptor, o->gss_strict_acceptor); ++ dump_cfg_fmtint(sGssStoreRekey, o->gss_store_rekey); ++ dump_cfg_string(sGssKexAlgorithms, o->gss_kex_algorithms); + #endif + dump_cfg_fmtint(sPasswordAuthentication, o->password_authentication); + dump_cfg_fmtint(sKbdInteractiveAuthentication, +diff --git a/servconf.h b/servconf.h +index 7ad43de87..38a68d576 100644 +--- a/servconf.h ++++ b/servconf.h +@@ -141,8 +141,11 @@ typedef struct { + int kerberos_get_afs_token; /* If true, try to get AFS token if + * authenticated with Kerberos. */ + int gss_authentication; /* If true, permit GSSAPI authentication */ ++ int gss_keyex; /* If true, permit GSSAPI key exchange */ + int gss_cleanup_creds; /* If true, destroy cred cache on logout */ + int gss_strict_acceptor; /* If true, restrict the GSSAPI acceptor name */ ++ int gss_store_rekey; ++ char *gss_kex_algorithms; /* GSSAPI kex methods to be offered by client. */ + int password_authentication; /* If true, permit password + * authentication. */ + int kbd_interactive_authentication; /* If true, permit */ +diff --git a/session.c b/session.c +index f30d7ac51..96960f2da 100644 +--- a/session.c ++++ b/session.c +@@ -2680,13 +2680,19 @@ do_cleanup(struct ssh *ssh, Authctxt *authctxt) + + #ifdef KRB5 + if (options.kerberos_ticket_cleanup && +- authctxt->krb5_ctx) ++ authctxt->krb5_ctx) { ++ temporarily_use_uid(authctxt->pw); + krb5_cleanup_proc(authctxt); ++ restore_uid(); ++ } + #endif + + #ifdef GSSAPI +- if (options.gss_cleanup_creds) ++ if (options.gss_cleanup_creds) { ++ temporarily_use_uid(authctxt->pw); + ssh_gssapi_cleanup_creds(); ++ restore_uid(); ++ } + #endif + + /* remove agent socket */ +diff --git a/ssh-gss.h b/ssh-gss.h +index a8af117d2..6303ce185 100644 +--- a/ssh-gss.h ++++ b/ssh-gss.h +@@ -1,6 +1,6 @@ + /* $OpenBSD: ssh-gss.h,v 1.15 2021/01/27 10:05:28 djm Exp $ */ + /* +- * Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved. ++ * Copyright (c) 2001-2009 Simon Wilkinson. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions +@@ -61,10 +61,34 @@ + + #define SSH_GSS_OIDTYPE 0x06 + ++#define SSH2_MSG_KEXGSS_INIT 30 ++#define SSH2_MSG_KEXGSS_CONTINUE 31 ++#define SSH2_MSG_KEXGSS_COMPLETE 32 ++#define SSH2_MSG_KEXGSS_HOSTKEY 33 ++#define SSH2_MSG_KEXGSS_ERROR 34 ++#define SSH2_MSG_KEXGSS_GROUPREQ 40 ++#define SSH2_MSG_KEXGSS_GROUP 41 ++#define KEX_GSS_GRP1_SHA1_ID "gss-group1-sha1-" ++#define KEX_GSS_GRP14_SHA1_ID "gss-group14-sha1-" ++#define KEX_GSS_GRP14_SHA256_ID "gss-group14-sha256-" ++#define KEX_GSS_GRP16_SHA512_ID "gss-group16-sha512-" ++#define KEX_GSS_GEX_SHA1_ID "gss-gex-sha1-" ++#define KEX_GSS_NISTP256_SHA256_ID "gss-nistp256-sha256-" ++#define KEX_GSS_C25519_SHA256_ID "gss-curve25519-sha256-" ++ ++#define GSS_KEX_DEFAULT_KEX \ ++ KEX_GSS_GRP14_SHA256_ID "," \ ++ KEX_GSS_GRP16_SHA512_ID "," \ ++ KEX_GSS_NISTP256_SHA256_ID "," \ ++ KEX_GSS_C25519_SHA256_ID "," \ ++ KEX_GSS_GRP14_SHA1_ID "," \ ++ KEX_GSS_GEX_SHA1_ID ++ + typedef struct { + char *filename; + char *envvar; + char *envval; ++ struct passwd *owner; + void *data; + } ssh_gssapi_ccache; + +@@ -72,8 +96,11 @@ typedef struct { + gss_buffer_desc displayname; + gss_buffer_desc exportedname; + gss_cred_id_t creds; ++ gss_name_t name; + struct ssh_gssapi_mech_struct *mech; + ssh_gssapi_ccache store; ++ int used; ++ int updated; + } ssh_gssapi_client; + + typedef struct ssh_gssapi_mech_struct { +@@ -84,6 +111,7 @@ typedef struct ssh_gssapi_mech_struct { + int (*userok) (ssh_gssapi_client *, char *); + int (*localname) (ssh_gssapi_client *, char **); + void (*storecreds) (ssh_gssapi_client *); ++ int (*updatecreds) (ssh_gssapi_ccache *, ssh_gssapi_client *); + } ssh_gssapi_mech; + + typedef struct { +@@ -94,10 +122,11 @@ typedef struct { + gss_OID oid; /* client */ + gss_cred_id_t creds; /* server */ + gss_name_t client; /* server */ +- gss_cred_id_t client_creds; /* server */ ++ gss_cred_id_t client_creds; /* both */ + } Gssctxt; + + extern ssh_gssapi_mech *supported_mechs[]; ++extern Gssctxt *gss_kex_context; + + int ssh_gssapi_check_oid(Gssctxt *, void *, size_t); + void ssh_gssapi_set_oid_data(Gssctxt *, void *, size_t); +@@ -109,6 +138,7 @@ OM_uint32 ssh_gssapi_test_oid_supported(OM_uint32 *, gss_OID, int *); + + struct sshbuf; + int ssh_gssapi_get_buffer_desc(struct sshbuf *, gss_buffer_desc *); ++int ssh_gssapi_sshpkt_get_buffer_desc(struct ssh *, gss_buffer_desc *); + + OM_uint32 ssh_gssapi_import_name(Gssctxt *, const char *); + OM_uint32 ssh_gssapi_init_ctx(Gssctxt *, int, +@@ -123,17 +153,33 @@ void ssh_gssapi_delete_ctx(Gssctxt **); + OM_uint32 ssh_gssapi_sign(Gssctxt *, gss_buffer_t, gss_buffer_t); + void ssh_gssapi_buildmic(struct sshbuf *, const char *, + const char *, const char *, const struct sshbuf *); +-int ssh_gssapi_check_mechanism(Gssctxt **, gss_OID, const char *); ++int ssh_gssapi_check_mechanism(Gssctxt **, gss_OID, const char *, const char *); ++OM_uint32 ssh_gssapi_client_identity(Gssctxt *, const char *); ++int ssh_gssapi_credentials_updated(Gssctxt *); + + /* In the server */ ++typedef int ssh_gssapi_check_fn(Gssctxt **, gss_OID, const char *, ++ const char *); ++char *ssh_gssapi_client_mechanisms(const char *, const char *, const char *); ++char *ssh_gssapi_kex_mechs(gss_OID_set, ssh_gssapi_check_fn *, const char *, ++ const char *, const char *); ++gss_OID ssh_gssapi_id_kex(Gssctxt *, char *, int); ++int ssh_gssapi_server_check_mech(Gssctxt **,gss_OID, const char *, ++ const char *); + OM_uint32 ssh_gssapi_server_ctx(Gssctxt **, gss_OID); +-int ssh_gssapi_userok(char *name); ++int ssh_gssapi_userok(char *name, struct passwd *, int kex); + OM_uint32 ssh_gssapi_checkmic(Gssctxt *, gss_buffer_t, gss_buffer_t); + void ssh_gssapi_do_child(char ***, u_int *); + void ssh_gssapi_cleanup_creds(void); + void ssh_gssapi_storecreds(void); + const char *ssh_gssapi_displayname(void); + ++char *ssh_gssapi_server_mechanisms(void); ++int ssh_gssapi_oid_table_ok(void); ++ ++int ssh_gssapi_update_creds(ssh_gssapi_ccache *store); ++void ssh_gssapi_rekey_creds(void); ++ + #endif /* GSSAPI */ + + #endif /* _SSH_GSS_H */ +diff --git a/ssh-null.c b/ssh-null.c +new file mode 100644 +index 000000000..a934bda77 +--- /dev/null ++++ b/ssh-null.c +@@ -0,0 +1,108 @@ ++/* ++ * Copyright (c) 2023 Colin Watson. 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" ++ ++#ifdef GSSAPI ++ ++#include "sshbuf.h" ++#include "ssherr.h" ++#include "sshkey.h" ++ ++static int ++ssh_null_equal(const struct sshkey *a, const struct sshkey *b) ++{ ++ return 1; ++} ++ ++static int ++ssh_null_serialize_public(const struct sshkey *key, struct sshbuf *b, ++ enum sshkey_serialize_rep opts) ++{ ++ return SSH_ERR_KEY_TYPE_UNKNOWN; ++} ++ ++static int ++ssh_null_deserialize_public(const char *ktype, struct sshbuf *b, ++ struct sshkey *key) ++{ ++ return SSH_ERR_KEY_TYPE_UNKNOWN; ++} ++ ++static int ++ssh_null_serialize_private(const struct sshkey *key, struct sshbuf *b, ++ enum sshkey_serialize_rep opts) ++{ ++ return SSH_ERR_KEY_TYPE_UNKNOWN; ++} ++ ++static int ++ssh_null_deserialize_private(const char *ktype, struct sshbuf *b, ++ struct sshkey *key) ++{ ++ return SSH_ERR_KEY_TYPE_UNKNOWN; ++} ++ ++static int ++ssh_null_copy_public(const struct sshkey *from, struct sshkey *to) ++{ ++ return SSH_ERR_KEY_TYPE_UNKNOWN; ++} ++ ++static int ++ssh_null_verify(const struct sshkey *key, const u_char *sig, size_t siglen, ++ const u_char *data, size_t dlen, const char *alg, u_int compat, ++ struct sshkey_sig_details **detailsp) ++{ ++ return SSH_ERR_KEY_TYPE_UNKNOWN; ++} ++ ++static const struct sshkey_impl_funcs sshkey_null_funcs = { ++ /* .size = */ NULL, ++ /* .alloc = */ NULL, ++ /* .cleanup = */ NULL, ++ /* .equal = */ ssh_null_equal, ++ /* .ssh_serialize_public = */ ssh_null_serialize_public, ++ /* .ssh_deserialize_public = */ ssh_null_deserialize_public, ++ /* .ssh_serialize_private = */ ssh_null_serialize_private, ++ /* .ssh_deserialize_private = */ ssh_null_deserialize_private, ++ /* .generate = */ NULL, ++ /* .copy_public = */ ssh_null_copy_public, ++ /* .sign = */ NULL, ++ /* .verify = */ ssh_null_verify, ++}; ++ ++const struct sshkey_impl sshkey_null_impl = { ++ /* .name = */ "null", ++ /* .shortname = */ "null", ++ /* .sigalg = */ NULL, ++ /* .type = */ KEY_NULL, ++ /* .nid = */ 0, ++ /* .cert = */ 0, ++ /* .sigonly = */ 0, ++ /* .keybits = */ 0, ++ /* .funcs = */ &sshkey_null_funcs, ++}; ++ ++#endif /* GSSAPI */ +diff --git a/ssh.1 b/ssh.1 +index a3d1ba163..dfd80b8bc 100644 +--- a/ssh.1 ++++ b/ssh.1 +@@ -534,7 +534,13 @@ For full details of the options listed below, and their possible values, see + .It GatewayPorts + .It GlobalKnownHostsFile + .It GSSAPIAuthentication ++.It GSSAPIKeyExchange ++.It GSSAPIClientIdentity + .It GSSAPIDelegateCredentials ++.It GSSAPIKexAlgorithms ++.It GSSAPIRenewalForcesRekey ++.It GSSAPIServerIdentity ++.It GSSAPITrustDns + .It HashKnownHosts + .It Host + .It HostbasedAcceptedAlgorithms +@@ -612,6 +618,8 @@ flag), + (supported message integrity codes), + .Ar kex + (key exchange algorithms), ++.Ar kex-gss ++(GSSAPI key exchange algorithms), + .Ar key + (key types), + .Ar key-cert +diff --git a/ssh.c b/ssh.c +index 87454b84a..855777d7f 100644 +--- a/ssh.c ++++ b/ssh.c +@@ -787,6 +787,8 @@ main(int ac, char **av) + else if (strcmp(optarg, "kex") == 0 || + strcasecmp(optarg, "KexAlgorithms") == 0) + cp = kex_alg_list('\n'); ++ else if (strcmp(optarg, "kex-gss") == 0) ++ cp = kex_gss_alg_list('\n'); + else if (strcmp(optarg, "key") == 0) + cp = sshkey_alg_list(0, 0, 0, '\n'); + else if (strcmp(optarg, "key-cert") == 0) +@@ -814,8 +816,8 @@ main(int ac, char **av) + } else if (strcmp(optarg, "help") == 0) { + cp = xstrdup( + "cipher\ncipher-auth\ncompression\nkex\n" +- "key\nkey-cert\nkey-plain\nkey-sig\nmac\n" +- "protocol-version\nsig"); ++ "kex-gss\nkey\nkey-cert\nkey-plain\n" ++ "key-sig\nmac\nprotocol-version\nsig"); + } + if (cp == NULL) + fatal("Unsupported query \"%s\"", optarg); +diff --git a/ssh_config b/ssh_config +index 842ea866c..52aae8692 100644 +--- a/ssh_config ++++ b/ssh_config +@@ -24,6 +24,8 @@ + # HostbasedAuthentication no + # GSSAPIAuthentication no + # GSSAPIDelegateCredentials no ++# GSSAPIKeyExchange no ++# GSSAPITrustDNS no + # BatchMode no + # CheckHostIP yes + # AddressFamily any +diff --git a/ssh_config.5 b/ssh_config.5 +index 9eb6b9779..43f3b642c 100644 +--- a/ssh_config.5 ++++ b/ssh_config.5 +@@ -839,10 +839,67 @@ The default is + Specifies whether user authentication based on GSSAPI is allowed. + The default is + .Cm no . ++.It Cm GSSAPIClientIdentity ++If set, specifies the GSSAPI client identity that ssh should use when ++connecting to the server. The default is unset, which means that the default ++identity will be used. + .It Cm GSSAPIDelegateCredentials + Forward (delegate) credentials to the server. + The default is + .Cm no . ++.It Cm GSSAPIKeyExchange ++Specifies whether key exchange based on GSSAPI may be used. When using ++GSSAPI key exchange the server need not have a host key. ++The default is ++.Dq no . ++.It Cm GSSAPIRenewalForcesRekey ++If set to ++.Dq yes ++then renewal of the client's GSSAPI credentials will force the rekeying of the ++ssh connection. With a compatible server, this will delegate the renewed ++credentials to a session on the server. ++.Pp ++Checks are made to ensure that credentials are only propagated when the new ++credentials match the old ones on the originating client and where the ++receiving server still has the old set in its cache. ++.Pp ++The default is ++.Dq no . ++.Pp ++For this to work ++.Cm GSSAPIKeyExchange ++needs to be enabled in the server and also used by the client. ++.It Cm GSSAPIServerIdentity ++If set, specifies the GSSAPI server identity that ssh should expect when ++connecting to the server. The default is unset, which means that the ++expected GSSAPI server identity will be determined from the target ++hostname. ++.It Cm GSSAPITrustDns ++Set to ++.Dq yes ++to indicate that the DNS is trusted to securely canonicalize ++the name of the host being connected to. If ++.Dq no , ++the hostname entered on the ++command line will be passed untouched to the GSSAPI library. ++The default is ++.Dq no . ++.It Cm GSSAPIKexAlgorithms ++The list of key exchange algorithms that are offered for GSSAPI ++key exchange. Possible values are ++.Bd -literal -offset 3n ++gss-gex-sha1-, ++gss-group1-sha1-, ++gss-group14-sha1-, ++gss-group14-sha256-, ++gss-group16-sha512-, ++gss-nistp256-sha256-, ++gss-curve25519-sha256- ++.Ed ++.Pp ++The default is ++.Dq gss-group14-sha256-,gss-group16-sha512-,gss-nistp256-sha256-,gss-curve25519-sha256-,gss-gex-sha1-,gss-group14-sha1- . ++This option only applies to connections using GSSAPI. + .It Cm HashKnownHosts + Indicates that + .Xr ssh 1 +diff --git a/sshconnect2.c b/sshconnect2.c +index 58fe98db2..cb6a94e76 100644 +--- a/sshconnect2.c ++++ b/sshconnect2.c +@@ -81,8 +81,6 @@ + #endif + + /* import */ +-extern char *client_version_string; +-extern char *server_version_string; + extern Options options; + + /* +@@ -226,6 +224,11 @@ ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port, + char *prop_kex = NULL, *prop_enc = NULL, *prop_hostkey = NULL; + int r, use_known_hosts_order = 0; + ++#if defined(GSSAPI) && defined(WITH_OPENSSL) ++ char *orig = NULL, *gss = NULL; ++ char *gss_host = NULL; ++#endif ++ + xxx_host = host; + xxx_hostaddr = hostaddr; + xxx_conn_info = cinfo; +@@ -269,6 +272,42 @@ ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port, + compat_pkalg_proposal(ssh, options.hostkeyalgorithms); + } + ++#if defined(GSSAPI) && defined(WITH_OPENSSL) ++ if (options.gss_keyex) { ++ /* Add the GSSAPI mechanisms currently supported on this ++ * client to the key exchange algorithm proposal */ ++ orig = myproposal[PROPOSAL_KEX_ALGS]; ++ ++ if (options.gss_server_identity) { ++ gss_host = xstrdup(options.gss_server_identity); ++ } else if (options.gss_trust_dns) { ++ gss_host = remote_hostname(ssh); ++ /* Fall back to specified host if we are using proxy command ++ * and can not use DNS on that socket */ ++ if (strcmp(gss_host, "UNKNOWN") == 0) { ++ free(gss_host); ++ gss_host = xstrdup(host); ++ } ++ } else { ++ gss_host = xstrdup(host); ++ } ++ ++ gss = ssh_gssapi_client_mechanisms(gss_host, ++ options.gss_client_identity, options.gss_kex_algorithms); ++ if (gss) { ++ debug("Offering GSSAPI proposal: %s", gss); ++ xasprintf(&myproposal[PROPOSAL_KEX_ALGS], ++ "%s,%s", gss, orig); ++ ++ /* If we've got GSSAPI algorithms, then we also support the ++ * 'null' hostkey, as a last resort */ ++ orig = myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS]; ++ xasprintf(&myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS], ++ "%s,null", orig); ++ } ++ } ++#endif ++ + if (options.rekey_limit || options.rekey_interval) + ssh_packet_set_rekey_limits(ssh, options.rekey_limit, + options.rekey_interval); +@@ -287,16 +326,46 @@ ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port, + # ifdef OPENSSL_HAS_ECC + ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client; + # endif +-#endif ++# ifdef GSSAPI ++ if (options.gss_keyex) { ++ ssh->kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_client; ++ ssh->kex->kex[KEX_GSS_GRP14_SHA1] = kexgss_client; ++ ssh->kex->kex[KEX_GSS_GRP14_SHA256] = kexgss_client; ++ ssh->kex->kex[KEX_GSS_GRP16_SHA512] = kexgss_client; ++ ssh->kex->kex[KEX_GSS_GEX_SHA1] = kexgssgex_client; ++ ssh->kex->kex[KEX_GSS_NISTP256_SHA256] = kexgss_client; ++ ssh->kex->kex[KEX_GSS_C25519_SHA256] = kexgss_client; ++ } ++# endif ++#endif /* WITH_OPENSSL */ + ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client; + ssh->kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_client; + ssh->kex->verify_host_key=&verify_host_key_callback; + ++#if defined(GSSAPI) && defined(WITH_OPENSSL) ++ if (options.gss_keyex) { ++ ssh->kex->gss_deleg_creds = options.gss_deleg_creds; ++ ssh->kex->gss_trust_dns = options.gss_trust_dns; ++ ssh->kex->gss_client = options.gss_client_identity; ++ ssh->kex->gss_host = gss_host; ++ } ++#endif ++ + ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &ssh->kex->done); + + /* remove ext-info from the KEX proposals for rekeying */ + myproposal[PROPOSAL_KEX_ALGS] = + compat_kex_proposal(ssh, options.kex_algorithms); ++#if defined(GSSAPI) && defined(WITH_OPENSSL) ++ /* repair myproposal after it was crumpled by the */ ++ /* ext-info removal above */ ++ if (gss) { ++ orig = myproposal[PROPOSAL_KEX_ALGS]; ++ xasprintf(&myproposal[PROPOSAL_KEX_ALGS], ++ "%s,%s", gss, orig); ++ free(gss); ++ } ++#endif + if ((r = kex_prop2buf(ssh->kex->my, myproposal)) != 0) + fatal_r(r, "kex_prop2buf"); + +@@ -394,6 +463,7 @@ static int input_gssapi_response(int type, u_int32_t, struct ssh *); + static int input_gssapi_token(int type, u_int32_t, struct ssh *); + static int input_gssapi_error(int, u_int32_t, struct ssh *); + static int input_gssapi_errtok(int, u_int32_t, struct ssh *); ++static int userauth_gsskeyex(struct ssh *); + #endif + + void userauth(struct ssh *, char *); +@@ -410,6 +480,11 @@ static char *authmethods_get(void); + + Authmethod authmethods[] = { + #ifdef GSSAPI ++ {"gssapi-keyex", ++ userauth_gsskeyex, ++ NULL, ++ &options.gss_keyex, ++ NULL}, + {"gssapi-with-mic", + userauth_gssapi, + userauth_gssapi_cleanup, +@@ -785,12 +860,32 @@ userauth_gssapi(struct ssh *ssh) + OM_uint32 min; + int r, ok = 0; + gss_OID mech = NULL; ++ char *gss_host = NULL; ++ ++ if (options.gss_server_identity) { ++ gss_host = xstrdup(options.gss_server_identity); ++ } else if (options.gss_trust_dns) { ++ gss_host = remote_hostname(ssh); ++ /* Fall back to specified host if we are using proxy command ++ * and can not use DNS on that socket */ ++ if (strcmp(gss_host, "UNKNOWN") == 0) { ++ free(gss_host); ++ gss_host = xstrdup(authctxt->host); ++ } ++ } else { ++ gss_host = xstrdup(authctxt->host); ++ } + + /* Try one GSSAPI method at a time, rather than sending them all at + * once. */ + + if (authctxt->gss_supported_mechs == NULL) +- gss_indicate_mechs(&min, &authctxt->gss_supported_mechs); ++ if (GSS_ERROR(gss_indicate_mechs(&min, ++ &authctxt->gss_supported_mechs))) { ++ authctxt->gss_supported_mechs = NULL; ++ free(gss_host); ++ return 0; ++ } + + /* Check to see whether the mechanism is usable before we offer it */ + while (authctxt->mech_tried < authctxt->gss_supported_mechs->count && +@@ -799,13 +894,15 @@ userauth_gssapi(struct ssh *ssh) + elements[authctxt->mech_tried]; + /* My DER encoding requires length<128 */ + if (mech->length < 128 && ssh_gssapi_check_mechanism(&gssctxt, +- mech, authctxt->host)) { ++ mech, gss_host, options.gss_client_identity)) { + ok = 1; /* Mechanism works */ + } else { + authctxt->mech_tried++; + } + } + ++ free(gss_host); ++ + if (!ok || mech == NULL) + return 0; + +@@ -1046,6 +1143,55 @@ input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh) + free(lang); + return r; + } ++ ++int ++userauth_gsskeyex(struct ssh *ssh) ++{ ++ struct sshbuf *b = NULL; ++ Authctxt *authctxt = ssh->authctxt; ++ gss_buffer_desc gssbuf; ++ gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; ++ OM_uint32 ms; ++ int r; ++ ++ static int attempt = 0; ++ if (attempt++ >= 1) ++ return (0); ++ ++ if (gss_kex_context == NULL) { ++ debug("No valid Key exchange context"); ++ return (0); ++ } ++ ++ if ((b = sshbuf_new()) == NULL) ++ fatal_f("sshbuf_new failed"); ++ ++ ssh_gssapi_buildmic(b, authctxt->server_user, authctxt->service, ++ "gssapi-keyex", ssh->kex->session_id); ++ ++ if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL) ++ fatal_f("sshbuf_mutable_ptr failed"); ++ gssbuf.length = sshbuf_len(b); ++ ++ if (GSS_ERROR(ssh_gssapi_sign(gss_kex_context, &gssbuf, &mic))) { ++ sshbuf_free(b); ++ return (0); ++ } ++ ++ if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || ++ (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || ++ (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || ++ (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || ++ (r = sshpkt_put_string(ssh, mic.value, mic.length)) != 0 || ++ (r = sshpkt_send(ssh)) != 0) ++ fatal_fr(r, "parsing"); ++ ++ sshbuf_free(b); ++ gss_release_buffer(&ms, &mic); ++ ++ return (1); ++} ++ + #endif /* GSSAPI */ + + static int +diff --git a/sshd.c b/sshd.c +index 6321936c0..6ad9a845a 100644 +--- a/sshd.c ++++ b/sshd.c +@@ -803,8 +803,8 @@ notify_hostkeys(struct ssh *ssh) + } + debug3_f("sent %u hostkeys", nkeys); + if (nkeys == 0) +- fatal_f("no hostkeys"); +- if ((r = sshpkt_send(ssh)) != 0) ++ debug3_f("no hostkeys"); ++ else if ((r = sshpkt_send(ssh)) != 0) + sshpkt_fatal(ssh, r, "%s: send", __func__); + sshbuf_free(buf); + } +@@ -1914,7 +1914,8 @@ main(int ac, char **av) + free(fp); + } + accumulate_host_timing_secret(cfg, NULL); +- if (!sensitive_data.have_ssh2_key) { ++ /* The GSSAPI key exchange can run without a host key */ ++ if (!sensitive_data.have_ssh2_key && !options.gss_keyex) { + logit("sshd: no hostkeys available -- exiting."); + exit(1); + } +@@ -2398,6 +2399,48 @@ do_ssh2_kex(struct ssh *ssh) + myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = prop_hostkey = + compat_pkalg_proposal(ssh, list_hostkey_types()); + ++#if defined(GSSAPI) && defined(WITH_OPENSSL) ++ { ++ char *orig; ++ char *gss = NULL; ++ char *newstr = NULL; ++ orig = myproposal[PROPOSAL_KEX_ALGS]; ++ ++ /* ++ * If we don't have a host key, then there's no point advertising ++ * the other key exchange algorithms ++ */ ++ ++ if (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS]) == 0) ++ orig = NULL; ++ ++ if (options.gss_keyex) ++ gss = ssh_gssapi_server_mechanisms(); ++ else ++ gss = NULL; ++ ++ if (gss && orig) ++ xasprintf(&newstr, "%s,%s", gss, orig); ++ else if (gss) ++ newstr = gss; ++ else if (orig) ++ newstr = orig; ++ ++ /* ++ * If we've got GSSAPI mechanisms, then we've got the 'null' host ++ * key alg, but we can't tell people about it unless its the only ++ * host key algorithm we support ++ */ ++ if (gss && (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS])) == 0) ++ myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = "null"; ++ ++ if (newstr) ++ myproposal[PROPOSAL_KEX_ALGS] = newstr; ++ else ++ fatal("No supported key exchange algorithms"); ++ } ++#endif ++ + /* start key exchange */ + if ((r = kex_setup(ssh, myproposal)) != 0) + fatal_r(r, "kex_setup"); +@@ -2413,7 +2456,18 @@ do_ssh2_kex(struct ssh *ssh) + # ifdef OPENSSL_HAS_ECC + kex->kex[KEX_ECDH_SHA2] = kex_gen_server; + # endif +-#endif ++# ifdef GSSAPI ++ if (options.gss_keyex) { ++ kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_server; ++ kex->kex[KEX_GSS_GRP14_SHA1] = kexgss_server; ++ kex->kex[KEX_GSS_GRP14_SHA256] = kexgss_server; ++ kex->kex[KEX_GSS_GRP16_SHA512] = kexgss_server; ++ kex->kex[KEX_GSS_GEX_SHA1] = kexgssgex_server; ++ kex->kex[KEX_GSS_NISTP256_SHA256] = kexgss_server; ++ kex->kex[KEX_GSS_C25519_SHA256] = kexgss_server; ++ } ++# endif ++#endif /* WITH_OPENSSL */ + kex->kex[KEX_C25519_SHA256] = kex_gen_server; + kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_server; + kex->load_host_public_key=&get_hostkey_public_by_type; +diff --git a/sshd_config b/sshd_config +index 36894ace5..ecfe8d026 100644 +--- a/sshd_config ++++ b/sshd_config +@@ -69,6 +69,8 @@ AuthorizedKeysFile .ssh/authorized_keys + # GSSAPI options + #GSSAPIAuthentication no + #GSSAPICleanupCredentials yes ++#GSSAPIStrictAcceptorCheck yes ++#GSSAPIKeyExchange no + + # Set this to 'yes' to enable PAM authentication, account processing, + # and session processing. If this is enabled, PAM authentication will +diff --git a/sshd_config.5 b/sshd_config.5 +index 7313a7f79..83f840511 100644 +--- a/sshd_config.5 ++++ b/sshd_config.5 +@@ -719,6 +719,11 @@ Specifies whether to automatically destroy the user's credentials cache + on logout. + The default is + .Cm yes . ++.It Cm GSSAPIKeyExchange ++Specifies whether key exchange based on GSSAPI is allowed. GSSAPI key exchange ++doesn't rely on ssh keys to verify host identity. ++The default is ++.Cm no . + .It Cm GSSAPIStrictAcceptorCheck + Determines whether to be strict about the identity of the GSSAPI acceptor + a client authenticates against. +@@ -733,6 +738,31 @@ machine's default store. + This facility is provided to assist with operation on multi homed machines. + The default is + .Cm yes . ++.It Cm GSSAPIStoreCredentialsOnRekey ++Controls whether the user's GSSAPI credentials should be updated following a ++successful connection rekeying. This option can be used to accepted renewed ++or updated credentials from a compatible client. The default is ++.Dq no . ++.Pp ++For this to work ++.Cm GSSAPIKeyExchange ++needs to be enabled in the server and also used by the client. ++.It Cm GSSAPIKexAlgorithms ++The list of key exchange algorithms that are accepted by GSSAPI ++key exchange. Possible values are ++.Bd -literal -offset 3n ++gss-gex-sha1-, ++gss-group1-sha1-, ++gss-group14-sha1-, ++gss-group14-sha256-, ++gss-group16-sha512-, ++gss-nistp256-sha256-, ++gss-curve25519-sha256- ++.Ed ++.Pp ++The default is ++.Dq gss-group14-sha256-,gss-group16-sha512-,gss-nistp256-sha256-,gss-curve25519-sha256-,gss-gex-sha1-,gss-group14-sha1- . ++This option only applies to connections using GSSAPI. + .It Cm HostbasedAcceptedAlgorithms + Specifies the signature algorithms that will be accepted for hostbased + authentication as a list of comma-separated patterns. +diff --git a/sshkey.c b/sshkey.c +index 43712253d..35a423e92 100644 +--- a/sshkey.c ++++ b/sshkey.c +@@ -127,6 +127,9 @@ extern const struct sshkey_impl sshkey_dsa_cert_impl; + extern const struct sshkey_impl sshkey_xmss_impl; + extern const struct sshkey_impl sshkey_xmss_cert_impl; + #endif ++#ifdef GSSAPI ++extern const struct sshkey_impl sshkey_null_impl; ++#endif /* GSSAPI */ + + const struct sshkey_impl * const keyimpls[] = { + &sshkey_ed25519_impl, +@@ -164,6 +167,9 @@ const struct sshkey_impl * const keyimpls[] = { + &sshkey_xmss_impl, + &sshkey_xmss_cert_impl, + #endif ++#ifdef GSSAPI ++ &sshkey_null_impl, ++#endif /* GSSAPI */ + NULL + }; + +@@ -319,7 +325,7 @@ sshkey_alg_list(int certs_only, int plain_only, int include_sigonly, char sep) + + for (i = 0; keyimpls[i] != NULL; i++) { + impl = keyimpls[i]; +- if (impl->name == NULL) ++ if (impl->name == NULL || impl->type == KEY_NULL) + continue; + if (!include_sigonly && impl->sigonly) + continue; +diff --git a/sshkey.h b/sshkey.h +index 771c4bcee..a0742e8c2 100644 +--- a/sshkey.h ++++ b/sshkey.h +@@ -71,6 +71,7 @@ enum sshkey_types { + KEY_ECDSA_SK_CERT, + KEY_ED25519_SK, + KEY_ED25519_SK_CERT, ++ KEY_NULL, + KEY_UNSPEC + }; + |