From 03d2fde6ad89a51fef89d02617e8c711833a5abe Mon Sep 17 00:00:00 2001 From: Markus Friedl Date: Fri, 19 Jul 2013 07:37:49 +0000 Subject: add ssh-agent(1) support to sshd(8); allows encrypted hostkeys, or hostkeys on smartcards; most of the work by Zev Weiss; bz #1974 ok djm@ --- usr.bin/ssh/auth.h | 4 ++- usr.bin/ssh/kex.h | 3 +- usr.bin/ssh/kexdhs.c | 10 ++---- usr.bin/ssh/kexecdhs.c | 10 ++---- usr.bin/ssh/kexgexs.c | 11 ++----- usr.bin/ssh/monitor.c | 18 +++++++--- usr.bin/ssh/servconf.c | 18 ++++++++-- usr.bin/ssh/servconf.h | 3 +- usr.bin/ssh/session.c | 10 +++++- usr.bin/ssh/sshd.c | 83 ++++++++++++++++++++++++++++++++++++++++++----- usr.bin/ssh/sshd_config.5 | 16 +++++++-- 11 files changed, 144 insertions(+), 42 deletions(-) diff --git a/usr.bin/ssh/auth.h b/usr.bin/ssh/auth.h index 2ce518a17df..cb0db428172 100644 --- a/usr.bin/ssh/auth.h +++ b/usr.bin/ssh/auth.h @@ -1,4 +1,4 @@ -/* $OpenBSD: auth.h,v 1.75 2013/06/21 00:34:49 djm Exp $ */ +/* $OpenBSD: auth.h,v 1.76 2013/07/19 07:37:48 markus Exp $ */ /* * Copyright (c) 2000 Markus Friedl. All rights reserved. @@ -174,10 +174,12 @@ check_key_in_hostfiles(struct passwd *, Key *, const char *, /* hostkey handling */ Key *get_hostkey_by_index(int); +Key *get_hostkey_public_by_index(int); Key *get_hostkey_public_by_type(int); Key *get_hostkey_private_by_type(int); int get_hostkey_index(Key *); int ssh1_session_key(BIGNUM *); +void sshd_hostkey_sign(Key *, Key *, u_char **, u_int *, u_char *, u_int); /* debug messages during authentication */ void auth_debug_add(const char *fmt,...) __attribute__((format(printf, 1, 2))); diff --git a/usr.bin/ssh/kex.h b/usr.bin/ssh/kex.h index 28e15c8520b..6d8252c1290 100644 --- a/usr.bin/ssh/kex.h +++ b/usr.bin/ssh/kex.h @@ -1,4 +1,4 @@ -/* $OpenBSD: kex.h,v 1.55 2013/04/19 01:06:50 djm Exp $ */ +/* $OpenBSD: kex.h,v 1.56 2013/07/19 07:37:48 markus Exp $ */ /* * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. @@ -136,6 +136,7 @@ struct Kex { Key *(*load_host_public_key)(int); Key *(*load_host_private_key)(int); int (*host_key_index)(Key *); + void (*sign)(Key *, Key *, u_char **, u_int *, u_char *, u_int); void (*kex[KEX_MAX])(Kex *); }; diff --git a/usr.bin/ssh/kexdhs.c b/usr.bin/ssh/kexdhs.c index abbd54465bc..de085ba155b 100644 --- a/usr.bin/ssh/kexdhs.c +++ b/usr.bin/ssh/kexdhs.c @@ -1,4 +1,4 @@ -/* $OpenBSD: kexdhs.c,v 1.13 2013/05/17 00:13:13 djm Exp $ */ +/* $OpenBSD: kexdhs.c,v 1.14 2013/07/19 07:37:48 markus Exp $ */ /* * Copyright (c) 2001 Markus Friedl. All rights reserved. * @@ -77,9 +77,6 @@ kexdh_server(Kex *kex) if (server_host_public == NULL) fatal("Unsupported hostkey type %d", kex->hostkey_type); server_host_private = kex->load_host_private_key(kex->hostkey_type); - if (server_host_private == NULL) - fatal("Missing private key for hostkey type %d", - kex->hostkey_type); /* key, cert */ if ((dh_client_pub = BN_new()) == NULL) @@ -141,9 +138,8 @@ kexdh_server(Kex *kex) } /* sign H */ - if (PRIVSEP(key_sign(server_host_private, &signature, &slen, hash, - hashlen)) < 0) - fatal("kexdh_server: key_sign failed"); + kex->sign(server_host_private, server_host_public, &signature, &slen, + hash, hashlen); /* destroy_sensitive_data(); */ diff --git a/usr.bin/ssh/kexecdhs.c b/usr.bin/ssh/kexecdhs.c index 5a3307e5152..fbca7ea7b32 100644 --- a/usr.bin/ssh/kexecdhs.c +++ b/usr.bin/ssh/kexecdhs.c @@ -1,4 +1,4 @@ -/* $OpenBSD: kexecdhs.c,v 1.4 2013/05/17 00:13:13 djm Exp $ */ +/* $OpenBSD: kexecdhs.c,v 1.5 2013/07/19 07:37:48 markus Exp $ */ /* * Copyright (c) 2001 Markus Friedl. All rights reserved. * Copyright (c) 2010 Damien Miller. All rights reserved. @@ -74,9 +74,6 @@ kexecdh_server(Kex *kex) if (server_host_public == NULL) fatal("Unsupported hostkey type %d", kex->hostkey_type); server_host_private = kex->load_host_private_key(kex->hostkey_type); - if (server_host_private == NULL) - fatal("Missing private key for hostkey type %d", - kex->hostkey_type); debug("expecting SSH2_MSG_KEX_ECDH_INIT"); packet_read_expect(SSH2_MSG_KEX_ECDH_INIT); @@ -135,9 +132,8 @@ kexecdh_server(Kex *kex) } /* sign H */ - if (PRIVSEP(key_sign(server_host_private, &signature, &slen, - hash, hashlen)) < 0) - fatal("kexdh_server: key_sign failed"); + kex->sign(server_host_private, server_host_public, &signature, &slen, + hash, hashlen); /* destroy_sensitive_data(); */ diff --git a/usr.bin/ssh/kexgexs.c b/usr.bin/ssh/kexgexs.c index cabe3b5c813..1df2243c398 100644 --- a/usr.bin/ssh/kexgexs.c +++ b/usr.bin/ssh/kexgexs.c @@ -1,4 +1,4 @@ -/* $OpenBSD: kexgexs.c,v 1.15 2013/05/17 00:13:13 djm Exp $ */ +/* $OpenBSD: kexgexs.c,v 1.16 2013/07/19 07:37:48 markus Exp $ */ /* * Copyright (c) 2000 Niels Provos. All rights reserved. * Copyright (c) 2001 Markus Friedl. All rights reserved. @@ -65,10 +65,6 @@ kexgex_server(Kex *kex) if (server_host_public == NULL) fatal("Unsupported hostkey type %d", kex->hostkey_type); server_host_private = kex->load_host_private_key(kex->hostkey_type); - if (server_host_private == NULL) - fatal("Missing private key for hostkey type %d", - kex->hostkey_type); - type = packet_read(); switch (type) { @@ -184,9 +180,8 @@ kexgex_server(Kex *kex) } /* sign H */ - if (PRIVSEP(key_sign(server_host_private, &signature, &slen, hash, - hashlen)) < 0) - fatal("kexgex_server: key_sign failed"); + kex->sign(server_host_private, server_host_public, &signature, &slen, + hash, hashlen); /* destroy_sensitive_data(); */ diff --git a/usr.bin/ssh/monitor.c b/usr.bin/ssh/monitor.c index 4fad8eee5ee..9c03bc98d45 100644 --- a/usr.bin/ssh/monitor.c +++ b/usr.bin/ssh/monitor.c @@ -1,4 +1,4 @@ -/* $OpenBSD: monitor.c,v 1.126 2013/06/21 00:34:49 djm Exp $ */ +/* $OpenBSD: monitor.c,v 1.127 2013/07/19 07:37:48 markus Exp $ */ /* * Copyright 2002 Niels Provos * Copyright 2002 Markus Friedl @@ -75,6 +75,7 @@ #include "ssh2.h" #include "jpake.h" #include "roaming.h" +#include "authfd.h" #ifdef GSSAPI static Gssctxt *gsscontext = NULL; @@ -594,6 +595,8 @@ mm_answer_moduli(int sock, Buffer *m) return (0); } +extern AuthenticationConnection *auth_conn; + int mm_answer_sign(int sock, Buffer *m) { @@ -622,10 +625,16 @@ mm_answer_sign(int sock, Buffer *m) memcpy(session_id2, p, session_id2_len); } - if ((key = get_hostkey_by_index(keyid)) == NULL) + if ((key = get_hostkey_by_index(keyid)) != NULL) { + if (key_sign(key, &signature, &siglen, p, datlen) < 0) + fatal("%s: key_sign failed", __func__); + } else if ((key = get_hostkey_public_by_index(keyid)) != NULL && + auth_conn != NULL) { + if (ssh_agent_sign(auth_conn, key, &signature, &siglen, p, + datlen) < 0) + fatal("%s: ssh_agent_sign failed", __func__); + } else fatal("%s: no hostkey from index %d", __func__, keyid); - if (key_sign(key, &signature, &siglen, p, datlen) < 0) - fatal("%s: key_sign failed", __func__); debug3("%s: signature %p(%u)", __func__, signature, siglen); @@ -1533,6 +1542,7 @@ mm_get_kex(Buffer *m) kex->load_host_public_key=&get_hostkey_public_by_type; kex->load_host_private_key=&get_hostkey_private_by_type; kex->host_key_index=&get_hostkey_index; + kex->sign = sshd_hostkey_sign; return (kex); } diff --git a/usr.bin/ssh/servconf.c b/usr.bin/ssh/servconf.c index 518d86e7547..5ee9bb9db95 100644 --- a/usr.bin/ssh/servconf.c +++ b/usr.bin/ssh/servconf.c @@ -1,5 +1,5 @@ -/* $OpenBSD: servconf.c,v 1.239 2013/05/17 00:13:14 djm Exp $ */ +/* $OpenBSD: servconf.c,v 1.240 2013/07/19 07:37:48 markus Exp $ */ /* * Copyright (c) 1995 Tatu Ylonen , Espoo, Finland * All rights reserved @@ -70,6 +70,7 @@ initialize_server_options(ServerOptions *options) options->address_family = -1; options->num_host_key_files = 0; options->num_host_cert_files = 0; + options->host_key_agent = NULL; options->pid_file = NULL; options->server_key_bits = -1; options->login_grace_time = -1; @@ -315,7 +316,7 @@ typedef enum { sRevokedKeys, sTrustedUserCAKeys, sAuthorizedPrincipalsFile, sKexAlgorithms, sIPQoS, sVersionAddendum, sAuthorizedKeysCommand, sAuthorizedKeysCommandUser, - sAuthenticationMethods, + sAuthenticationMethods, sHostKeyAgent, sDeprecated, sUnsupported } ServerOpCodes; @@ -332,6 +333,7 @@ static struct { { "port", sPort, SSHCFG_GLOBAL }, { "hostkey", sHostKeyFile, SSHCFG_GLOBAL }, { "hostdsakey", sHostKeyFile, SSHCFG_GLOBAL }, /* alias */ + { "hostkeyagent", sHostKeyAgent, SSHCFG_GLOBAL }, { "pidfile", sPidFile, SSHCFG_GLOBAL }, { "serverkeybits", sServerKeyBits, SSHCFG_GLOBAL }, { "logingracetime", sLoginGraceTime, SSHCFG_GLOBAL }, @@ -931,6 +933,17 @@ process_server_config_line(ServerOptions *options, char *line, } break; + case sHostKeyAgent: + charptr = &options->host_key_agent; + arg = strdelim(&cp); + if (!arg || *arg == '\0') + fatal("%s line %d: missing socket name.", + filename, linenum); + if (*activep && *charptr == NULL) + *charptr = !strcmp(arg, SSH_AUTHSOCKET_ENV_NAME) ? + xstrdup(arg) : derelativise_path(arg); + break; + case sHostCertificate: intptr = &options->num_host_cert_files; if (*intptr >= MAX_HOSTKEYS) @@ -1959,6 +1972,7 @@ dump_config(ServerOptions *o) dump_cfg_string(sVersionAddendum, o->version_addendum); dump_cfg_string(sAuthorizedKeysCommand, o->authorized_keys_command); dump_cfg_string(sAuthorizedKeysCommandUser, o->authorized_keys_command_user); + dump_cfg_string(sHostKeyAgent, o->host_key_agent); /* string arguments requiring a lookup */ dump_cfg_string(sLogLevel, log_level_name(o->log_level)); diff --git a/usr.bin/ssh/servconf.h b/usr.bin/ssh/servconf.h index d32f2a141fe..fd7c7151ba9 100644 --- a/usr.bin/ssh/servconf.h +++ b/usr.bin/ssh/servconf.h @@ -1,4 +1,4 @@ -/* $OpenBSD: servconf.h,v 1.108 2013/05/16 04:09:14 dtucker Exp $ */ +/* $OpenBSD: servconf.h,v 1.109 2013/07/19 07:37:48 markus Exp $ */ /* * Author: Tatu Ylonen @@ -65,6 +65,7 @@ typedef struct { int num_host_key_files; /* Number of files for host keys. */ char *host_cert_files[MAX_HOSTCERTS]; /* Files containing host certs. */ int num_host_cert_files; /* Number of files for host certs. */ + char *host_key_agent; /* ssh-agent socket for host keys. */ char *pid_file; /* Where to put our pid */ int server_key_bits;/* Size of the server key. */ int login_grace_time; /* Disconnect if no auth in this time diff --git a/usr.bin/ssh/session.c b/usr.bin/ssh/session.c index cf04d33df6a..ef54cbc0b86 100644 --- a/usr.bin/ssh/session.c +++ b/usr.bin/ssh/session.c @@ -1,4 +1,4 @@ -/* $OpenBSD: session.c,v 1.265 2013/05/17 00:13:14 djm Exp $ */ +/* $OpenBSD: session.c,v 1.266 2013/07/19 07:37:48 markus Exp $ */ /* * Copyright (c) 1995 Tatu Ylonen , Espoo, Finland * All rights reserved @@ -70,6 +70,7 @@ #include "hostfile.h" #include "auth.h" #include "auth-options.h" +#include "authfd.h" #include "pathnames.h" #include "log.h" #include "servconf.h" @@ -1261,6 +1262,13 @@ launch_login(struct passwd *pw, const char *hostname) static void child_close_fds(void) { + extern AuthenticationConnection *auth_conn; + + if (auth_conn) { + ssh_close_authentication_connection(auth_conn); + auth_conn = NULL; + } + if (packet_get_connection_in() == packet_get_connection_out()) close(packet_get_connection_in()); else { diff --git a/usr.bin/ssh/sshd.c b/usr.bin/ssh/sshd.c index 76b7f2535be..c0b09330224 100644 --- a/usr.bin/ssh/sshd.c +++ b/usr.bin/ssh/sshd.c @@ -1,4 +1,4 @@ -/* $OpenBSD: sshd.c,v 1.403 2013/06/05 02:27:50 dtucker Exp $ */ +/* $OpenBSD: sshd.c,v 1.404 2013/07/19 07:37:48 markus Exp $ */ /* * Author: Tatu Ylonen * Copyright (c) 1995 Tatu Ylonen , Espoo, Finland @@ -90,6 +90,7 @@ #include "canohost.h" #include "hostfile.h" #include "auth.h" +#include "authfd.h" #include "misc.h" #include "msg.h" #include "dispatch.h" @@ -177,6 +178,10 @@ char *server_version_string = NULL; /* for rekeying XXX fixme */ Kex *xxx_kex; +/* Daemon's agent connection */ +AuthenticationConnection *auth_conn = NULL; +int have_agent = 0; + /* * Any really sensitive data in the application is contained in this * structure. The idea is that this structure could be locked into memory so @@ -189,6 +194,7 @@ struct { Key *server_key; /* ephemeral server key */ Key *ssh1_host_key; /* ssh1 host key */ Key **host_keys; /* all private host keys */ + Key **host_pubkeys; /* all public host keys */ Key **host_certificates; /* all public host certificates */ int have_ssh1_key; int have_ssh2_key; @@ -640,6 +646,8 @@ privsep_preauth(Authctxt *authctxt) debug2("Network child is on pid %ld", (long)pid); pmonitor->m_pid = pid; + if (have_agent) + auth_conn = ssh_get_authentication_connection(); if (box != NULL) ssh_sandbox_parent_preauth(box, pid); monitor_child_preauth(authctxt, pmonitor); @@ -749,6 +757,8 @@ list_hostkey_types(void) buffer_init(&b); for (i = 0; i < options.num_host_key_files; i++) { key = sensitive_data.host_keys[i]; + if (key == NULL) + key = sensitive_data.host_pubkeys[i]; if (key == NULL) continue; switch (key->type) { @@ -802,6 +812,8 @@ get_hostkey_by_type(int type, int need_private) break; default: key = sensitive_data.host_keys[i]; + if (key == NULL && !need_private) + key = sensitive_data.host_pubkeys[i]; break; } if (key != NULL && key->type == type) @@ -831,6 +843,14 @@ get_hostkey_by_index(int ind) return (sensitive_data.host_keys[ind]); } +Key * +get_hostkey_public_by_index(int ind) +{ + if (ind < 0 || ind >= options.num_host_key_files) + return (NULL); + return (sensitive_data.host_pubkeys[ind]); +} + int get_hostkey_index(Key *key) { @@ -843,6 +863,8 @@ get_hostkey_index(Key *key) } else { if (key == sensitive_data.host_keys[i]) return (i); + if (key == sensitive_data.host_pubkeys[i]) + return (i); } } return (-1); @@ -1310,6 +1332,8 @@ main(int ac, char **av) u_int64_t ibytes, obytes; mode_t new_umask; Key *key; + Key *pubkey; + int keytype; Authctxt *authctxt; struct connection_info *connection_info = get_connection_info(0, 0); @@ -1542,22 +1566,45 @@ main(int ac, char **av) debug("sshd version %s, %s", SSH_VERSION, SSLeay_version(SSLEAY_VERSION)); - /* load private host keys */ + /* load host keys */ sensitive_data.host_keys = xcalloc(options.num_host_key_files, sizeof(Key *)); - for (i = 0; i < options.num_host_key_files; i++) + sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files, + sizeof(Key *)); + for (i = 0; i < options.num_host_key_files; i++) { sensitive_data.host_keys[i] = NULL; + sensitive_data.host_pubkeys[i] = NULL; + } + + if (options.host_key_agent) { + if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME)) + setenv(SSH_AUTHSOCKET_ENV_NAME, + options.host_key_agent, 1); + have_agent = ssh_agent_present(); + } for (i = 0; i < options.num_host_key_files; i++) { key = key_load_private(options.host_key_files[i], "", NULL); + pubkey = key_load_public(options.host_key_files[i], NULL); sensitive_data.host_keys[i] = key; - if (key == NULL) { + sensitive_data.host_pubkeys[i] = pubkey; + + if (key == NULL && pubkey != NULL && pubkey->type != KEY_RSA1 && + have_agent) { + debug("will rely on agent for hostkey %s", + options.host_key_files[i]); + keytype = pubkey->type; + } else if (key != NULL) { + keytype = key->type; + } else { error("Could not load host key: %s", options.host_key_files[i]); sensitive_data.host_keys[i] = NULL; + sensitive_data.host_pubkeys[i] = NULL; continue; } - switch (key->type) { + + switch (keytype) { case KEY_RSA1: sensitive_data.ssh1_host_key = key; sensitive_data.have_ssh1_key = 1; @@ -1568,8 +1615,8 @@ main(int ac, char **av) sensitive_data.have_ssh2_key = 1; break; } - debug("private host key: #%d type %d %s", i, key->type, - key_type(key)); + debug("private host key: #%d type %d %s", i, keytype, + key_type(key ? key : pubkey)); } if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { logit("Disabling protocol version 1. Could not load host key"); @@ -1906,9 +1953,11 @@ main(int ac, char **av) buffer_init(&loginmsg); auth_debug_reset(); - if (use_privsep) + if (use_privsep) { if (privsep_preauth(authctxt) == 1) goto authenticated; + } else if (compat20 && have_agent) + auth_conn = ssh_get_authentication_connection(); /* perform the key exchange */ /* authenticate user and start session */ @@ -2194,6 +2243,23 @@ do_ssh1_kex(void) packet_write_wait(); } +void +sshd_hostkey_sign(Key *privkey, Key *pubkey, u_char **signature, u_int *slen, + u_char *data, u_int dlen) +{ + if (privkey) { + if (PRIVSEP(key_sign(privkey, signature, slen, data, dlen) < 0)) + fatal("%s: key_sign failed", __func__); + } else if (use_privsep) { + if (mm_key_sign(pubkey, signature, slen, data, dlen) < 0) + fatal("%s: pubkey_sign failed", __func__); + } else { + if (ssh_agent_sign(auth_conn, pubkey, signature, slen, data, + dlen)) + fatal("%s: ssh_agent_sign failed", __func__); + } +} + /* * SSH2 key exchange: diffie-hellman-group1-sha1 */ @@ -2244,6 +2310,7 @@ do_ssh2_kex(void) kex->load_host_public_key=&get_hostkey_public_by_type; kex->load_host_private_key=&get_hostkey_private_by_type; kex->host_key_index=&get_hostkey_index; + kex->sign = sshd_hostkey_sign; xxx_kex = kex; diff --git a/usr.bin/ssh/sshd_config.5 b/usr.bin/ssh/sshd_config.5 index 23970b8c391..f6870a2b581 100644 --- a/usr.bin/ssh/sshd_config.5 +++ b/usr.bin/ssh/sshd_config.5 @@ -33,8 +33,8 @@ .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. .\" -.\" $OpenBSD: sshd_config.5,v 1.161 2013/06/27 14:05:37 jmc Exp $ -.Dd $Mdocdate: June 27 2013 $ +.\" $OpenBSD: sshd_config.5,v 1.162 2013/07/19 07:37:48 markus Exp $ +.Dd $Mdocdate: July 19 2013 $ .Dt SSHD_CONFIG 5 .Os .Sh NAME @@ -547,6 +547,18 @@ keys are used for version 1 and or .Dq rsa are used for version 2 of the SSH protocol. +It is also possible to specify public host key files instead. +In this case operations on the private key will be delegated +to an +.Xr ssh-agent 1 . +.It Cm HostKeyAgent +Identifies the UNIX-domain socket used to communicate +with an agent that has access to the private host keys. +If +.Dq SSH_AUTH_SOCK +is specified, the location of the socket will be read from the +.Ev SSH_AUTH_SOCK +environment variable. .It Cm IgnoreRhosts Specifies that .Pa .rhosts -- cgit v1.2.3