Darren Tucker | 8cc3978 | 2003-11-03 20:05:03 +1100 | [diff] [blame^] | 1 | /* $OpenBSD: auth2-gss.c,v 1.4 2003/10/21 09:50:06 markus Exp $ */ |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 2 | |
| 3 | /* |
| 4 | * Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved. |
| 5 | * |
| 6 | * Redistribution and use in source and binary forms, with or without |
| 7 | * modification, are permitted provided that the following conditions |
| 8 | * are met: |
| 9 | * 1. Redistributions of source code must retain the above copyright |
| 10 | * notice, this list of conditions and the following disclaimer. |
| 11 | * 2. Redistributions in binary form must reproduce the above copyright |
| 12 | * notice, this list of conditions and the following disclaimer in the |
| 13 | * documentation and/or other materials provided with the distribution. |
| 14 | * |
| 15 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AS IS'' AND ANY EXPRESS OR |
| 16 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| 17 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
| 18 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
| 19 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| 20 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| 21 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| 22 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 23 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| 24 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 25 | */ |
| 26 | |
| 27 | #include "includes.h" |
| 28 | |
| 29 | #ifdef GSSAPI |
| 30 | |
| 31 | #include "auth.h" |
| 32 | #include "ssh2.h" |
| 33 | #include "xmalloc.h" |
| 34 | #include "log.h" |
| 35 | #include "dispatch.h" |
| 36 | #include "servconf.h" |
| 37 | #include "compat.h" |
| 38 | #include "packet.h" |
| 39 | #include "monitor_wrap.h" |
| 40 | |
| 41 | #include "ssh-gss.h" |
| 42 | |
| 43 | extern ServerOptions options; |
| 44 | |
| 45 | static void input_gssapi_token(int type, u_int32_t plen, void *ctxt); |
| 46 | static void input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt); |
| 47 | static void input_gssapi_errtok(int, u_int32_t, void *); |
| 48 | |
| 49 | /* |
| 50 | * We only support those mechanisms that we know about (ie ones that we know |
| 51 | * how to check local user kuserok and the like |
| 52 | */ |
| 53 | static int |
| 54 | userauth_gssapi(Authctxt *authctxt) |
| 55 | { |
| 56 | gss_OID_desc oid = {0, NULL}; |
| 57 | Gssctxt *ctxt = NULL; |
| 58 | int mechs; |
| 59 | gss_OID_set supported; |
| 60 | int present; |
| 61 | OM_uint32 ms; |
| 62 | u_int len; |
| 63 | char *doid = NULL; |
| 64 | |
| 65 | if (!authctxt->valid || authctxt->user == NULL) |
| 66 | return (0); |
| 67 | |
| 68 | mechs = packet_get_int(); |
| 69 | if (mechs == 0) { |
| 70 | debug("Mechanism negotiation is not supported"); |
| 71 | return (0); |
| 72 | } |
| 73 | |
| 74 | ssh_gssapi_supported_oids(&supported); |
| 75 | do { |
| 76 | mechs--; |
| 77 | |
| 78 | if (doid) |
| 79 | xfree(doid); |
| 80 | |
| 81 | doid = packet_get_string(&len); |
Darren Tucker | 8cc3978 | 2003-11-03 20:05:03 +1100 | [diff] [blame^] | 82 | if (len <= 2) |
| 83 | packet_disconnect("Short OID received"); |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 84 | |
| 85 | if (doid[0] != SSH_GSS_OIDTYPE || doid[1] != len-2) { |
| 86 | logit("Mechanism OID received using the old encoding form"); |
| 87 | oid.elements = doid; |
| 88 | oid.length = len; |
| 89 | } else { |
| 90 | oid.elements = doid + 2; |
| 91 | oid.length = len - 2; |
| 92 | } |
| 93 | gss_test_oid_set_member(&ms, &oid, supported, &present); |
| 94 | } while (mechs > 0 && !present); |
| 95 | |
| 96 | gss_release_oid_set(&ms, &supported); |
| 97 | |
| 98 | if (!present) { |
| 99 | xfree(doid); |
| 100 | return (0); |
| 101 | } |
| 102 | |
Damien Miller | 982d326 | 2003-09-02 22:59:01 +1000 | [diff] [blame] | 103 | if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &oid)))) { |
| 104 | xfree(doid); |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 105 | return (0); |
Damien Miller | 982d326 | 2003-09-02 22:59:01 +1000 | [diff] [blame] | 106 | } |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 107 | |
| 108 | authctxt->methoddata=(void *)ctxt; |
| 109 | |
| 110 | packet_start(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE); |
| 111 | |
| 112 | /* Return OID in same format as we received it*/ |
| 113 | packet_put_string(doid, len); |
| 114 | |
| 115 | packet_send(); |
| 116 | xfree(doid); |
| 117 | |
| 118 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); |
| 119 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); |
| 120 | authctxt->postponed = 1; |
| 121 | |
| 122 | return (0); |
| 123 | } |
| 124 | |
| 125 | static void |
| 126 | input_gssapi_token(int type, u_int32_t plen, void *ctxt) |
| 127 | { |
| 128 | Authctxt *authctxt = ctxt; |
| 129 | Gssctxt *gssctxt; |
| 130 | gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; |
| 131 | gss_buffer_desc recv_tok; |
| 132 | OM_uint32 maj_status, min_status; |
| 133 | u_int len; |
| 134 | |
| 135 | if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep)) |
| 136 | fatal("No authentication or GSSAPI context"); |
| 137 | |
| 138 | gssctxt = authctxt->methoddata; |
| 139 | recv_tok.value = packet_get_string(&len); |
| 140 | recv_tok.length = len; /* u_int vs. size_t */ |
| 141 | |
| 142 | packet_check_eom(); |
| 143 | |
| 144 | maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok, |
| 145 | &send_tok, NULL)); |
| 146 | |
| 147 | xfree(recv_tok.value); |
| 148 | |
| 149 | if (GSS_ERROR(maj_status)) { |
| 150 | if (send_tok.length != 0) { |
| 151 | packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK); |
| 152 | packet_put_string(send_tok.value, send_tok.length); |
| 153 | packet_send(); |
| 154 | } |
| 155 | authctxt->postponed = 0; |
| 156 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); |
| 157 | userauth_finish(authctxt, 0, "gssapi"); |
| 158 | } else { |
| 159 | if (send_tok.length != 0) { |
| 160 | packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN); |
| 161 | packet_put_string(send_tok.value, send_tok.length); |
| 162 | packet_send(); |
| 163 | } |
| 164 | if (maj_status == GSS_S_COMPLETE) { |
| 165 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); |
| 166 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, |
| 167 | &input_gssapi_exchange_complete); |
| 168 | } |
| 169 | } |
| 170 | |
| 171 | gss_release_buffer(&min_status, &send_tok); |
| 172 | } |
| 173 | |
| 174 | static void |
| 175 | input_gssapi_errtok(int type, u_int32_t plen, void *ctxt) |
| 176 | { |
| 177 | Authctxt *authctxt = ctxt; |
| 178 | Gssctxt *gssctxt; |
| 179 | gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; |
| 180 | gss_buffer_desc recv_tok; |
| 181 | OM_uint32 maj_status; |
Damien Miller | 55c47ed | 2003-09-02 22:14:07 +1000 | [diff] [blame] | 182 | u_int len; |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 183 | |
| 184 | if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep)) |
| 185 | fatal("No authentication or GSSAPI context"); |
| 186 | |
| 187 | gssctxt = authctxt->methoddata; |
Damien Miller | 55c47ed | 2003-09-02 22:14:07 +1000 | [diff] [blame] | 188 | recv_tok.value = packet_get_string(&len); |
| 189 | recv_tok.length = len; |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 190 | |
| 191 | packet_check_eom(); |
| 192 | |
| 193 | /* Push the error token into GSSAPI to see what it says */ |
| 194 | maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok, |
| 195 | &send_tok, NULL)); |
| 196 | |
| 197 | xfree(recv_tok.value); |
| 198 | |
| 199 | /* We can't return anything to the client, even if we wanted to */ |
| 200 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); |
| 201 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL); |
| 202 | |
| 203 | /* The client will have already moved on to the next auth */ |
| 204 | |
| 205 | gss_release_buffer(&maj_status, &send_tok); |
| 206 | } |
| 207 | |
| 208 | /* |
| 209 | * This is called when the client thinks we've completed authentication. |
| 210 | * It should only be enabled in the dispatch handler by the function above, |
| 211 | * which only enables it once the GSSAPI exchange is complete. |
| 212 | */ |
| 213 | |
| 214 | static void |
| 215 | input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt) |
| 216 | { |
| 217 | Authctxt *authctxt = ctxt; |
| 218 | Gssctxt *gssctxt; |
| 219 | int authenticated; |
| 220 | |
| 221 | if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep)) |
| 222 | fatal("No authentication or GSSAPI context"); |
| 223 | |
| 224 | gssctxt = authctxt->methoddata; |
| 225 | |
| 226 | /* |
| 227 | * We don't need to check the status, because the stored credentials |
| 228 | * which userok uses are only populated once the context init step |
| 229 | * has returned complete. |
| 230 | */ |
| 231 | |
| 232 | packet_check_eom(); |
| 233 | |
| 234 | authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user)); |
| 235 | |
| 236 | authctxt->postponed = 0; |
| 237 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); |
| 238 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL); |
| 239 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); |
| 240 | userauth_finish(authctxt, authenticated, "gssapi"); |
| 241 | } |
| 242 | |
| 243 | Authmethod method_gssapi = { |
| 244 | "gssapi", |
| 245 | userauth_gssapi, |
| 246 | &options.gss_authentication |
| 247 | }; |
| 248 | |
| 249 | #endif /* GSSAPI */ |