Damien Miller | 5f916c8 | 2005-11-05 15:05:28 +1100 | [diff] [blame] | 1 | /* $OpenBSD: gss-serv.c,v 1.12 2005/10/13 19:08:08 stevesk 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 "bufaux.h" |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 32 | #include "auth.h" |
| 33 | #include "log.h" |
| 34 | #include "channels.h" |
| 35 | #include "session.h" |
| 36 | #include "servconf.h" |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 37 | #include "xmalloc.h" |
| 38 | #include "getput.h" |
| 39 | |
| 40 | #include "ssh-gss.h" |
| 41 | |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 42 | static ssh_gssapi_client gssapi_client = |
| 43 | { GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER, |
| 44 | GSS_C_NO_CREDENTIAL, NULL, {NULL, NULL, NULL}}; |
| 45 | |
| 46 | ssh_gssapi_mech gssapi_null_mech = |
| 47 | { NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL}; |
| 48 | |
| 49 | #ifdef KRB5 |
| 50 | extern ssh_gssapi_mech gssapi_kerberos_mech; |
| 51 | #endif |
| 52 | |
| 53 | ssh_gssapi_mech* supported_mechs[]= { |
| 54 | #ifdef KRB5 |
| 55 | &gssapi_kerberos_mech, |
| 56 | #endif |
| 57 | &gssapi_null_mech, |
| 58 | }; |
| 59 | |
Damien Miller | 9fac263 | 2005-11-05 15:03:48 +1100 | [diff] [blame] | 60 | /* Unprivileged */ |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 61 | void |
| 62 | ssh_gssapi_supported_oids(gss_OID_set *oidset) |
| 63 | { |
| 64 | int i = 0; |
| 65 | OM_uint32 min_status; |
| 66 | int present; |
| 67 | gss_OID_set supported; |
| 68 | |
| 69 | gss_create_empty_oid_set(&min_status, oidset); |
| 70 | gss_indicate_mechs(&min_status, &supported); |
| 71 | |
| 72 | while (supported_mechs[i]->name != NULL) { |
| 73 | if (GSS_ERROR(gss_test_oid_set_member(&min_status, |
| 74 | &supported_mechs[i]->oid, supported, &present))) |
| 75 | present = 0; |
| 76 | if (present) |
| 77 | gss_add_oid_set_member(&min_status, |
| 78 | &supported_mechs[i]->oid, oidset); |
| 79 | i++; |
| 80 | } |
| 81 | } |
| 82 | |
| 83 | |
| 84 | /* Wrapper around accept_sec_context |
| 85 | * Requires that the context contains: |
| 86 | * oid |
| 87 | * credentials (from ssh_gssapi_acquire_cred) |
| 88 | */ |
Damien Miller | 9fac263 | 2005-11-05 15:03:48 +1100 | [diff] [blame] | 89 | /* Privileged */ |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 90 | OM_uint32 |
| 91 | ssh_gssapi_accept_ctx(Gssctxt *ctx, gss_buffer_desc *recv_tok, |
| 92 | gss_buffer_desc *send_tok, OM_uint32 *flags) |
| 93 | { |
| 94 | OM_uint32 status; |
| 95 | gss_OID mech; |
| 96 | |
| 97 | ctx->major = gss_accept_sec_context(&ctx->minor, |
| 98 | &ctx->context, ctx->creds, recv_tok, |
| 99 | GSS_C_NO_CHANNEL_BINDINGS, &ctx->client, &mech, |
| 100 | send_tok, flags, NULL, &ctx->client_creds); |
| 101 | |
| 102 | if (GSS_ERROR(ctx->major)) |
| 103 | ssh_gssapi_error(ctx); |
| 104 | |
| 105 | if (ctx->client_creds) |
| 106 | debug("Received some client credentials"); |
| 107 | else |
| 108 | debug("Got no client credentials"); |
| 109 | |
| 110 | status = ctx->major; |
| 111 | |
| 112 | /* Now, if we're complete and we have the right flags, then |
| 113 | * we flag the user as also having been authenticated |
| 114 | */ |
| 115 | |
| 116 | if (((flags == NULL) || ((*flags & GSS_C_MUTUAL_FLAG) && |
| 117 | (*flags & GSS_C_INTEG_FLAG))) && (ctx->major == GSS_S_COMPLETE)) { |
| 118 | if (ssh_gssapi_getclient(ctx, &gssapi_client)) |
| 119 | fatal("Couldn't convert client name"); |
| 120 | } |
| 121 | |
| 122 | return (status); |
| 123 | } |
| 124 | |
| 125 | /* |
| 126 | * This parses an exported name, extracting the mechanism specific portion |
| 127 | * to use for ACL checking. It verifies that the name belongs the mechanism |
| 128 | * originally selected. |
| 129 | */ |
| 130 | static OM_uint32 |
| 131 | ssh_gssapi_parse_ename(Gssctxt *ctx, gss_buffer_t ename, gss_buffer_t name) |
| 132 | { |
Damien Miller | eccb9de | 2005-06-17 12:59:34 +1000 | [diff] [blame] | 133 | u_char *tok; |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 134 | OM_uint32 offset; |
| 135 | OM_uint32 oidl; |
Damien Miller | 134350c | 2003-09-02 22:56:42 +1000 | [diff] [blame] | 136 | |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 137 | tok=ename->value; |
Damien Miller | 134350c | 2003-09-02 22:56:42 +1000 | [diff] [blame] | 138 | |
| 139 | /* |
| 140 | * Check that ename is long enough for all of the fixed length |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 141 | * header, and that the initial ID bytes are correct |
| 142 | */ |
| 143 | |
Damien Miller | 134350c | 2003-09-02 22:56:42 +1000 | [diff] [blame] | 144 | if (ename->length<6 || memcmp(tok,"\x04\x01", 2)!=0) |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 145 | return GSS_S_FAILURE; |
| 146 | |
| 147 | /* |
| 148 | * Extract the OID, and check it. Here GSSAPI breaks with tradition |
| 149 | * and does use the OID type and length bytes. To confuse things |
| 150 | * there are two lengths - the first including these, and the |
| 151 | * second without. |
| 152 | */ |
| 153 | |
| 154 | oidl = GET_16BIT(tok+2); /* length including next two bytes */ |
| 155 | oidl = oidl-2; /* turn it into the _real_ length of the variable OID */ |
| 156 | |
| 157 | /* |
| 158 | * Check the BER encoding for correct type and length, that the |
| 159 | * string is long enough and that the OID matches that in our context |
| 160 | */ |
| 161 | if (tok[4] != 0x06 || tok[5] != oidl || |
Damien Miller | 134350c | 2003-09-02 22:56:42 +1000 | [diff] [blame] | 162 | ename->length < oidl+6 || |
Damien Miller | 0dc1bef | 2005-07-17 17:22:45 +1000 | [diff] [blame] | 163 | !ssh_gssapi_check_oid(ctx,tok+6,oidl)) |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 164 | return GSS_S_FAILURE; |
| 165 | |
| 166 | offset = oidl+6; |
Damien Miller | 134350c | 2003-09-02 22:56:42 +1000 | [diff] [blame] | 167 | |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 168 | if (ename->length < offset+4) |
| 169 | return GSS_S_FAILURE; |
Damien Miller | 134350c | 2003-09-02 22:56:42 +1000 | [diff] [blame] | 170 | |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 171 | name->length = GET_32BIT(tok+offset); |
| 172 | offset += 4; |
Damien Miller | 134350c | 2003-09-02 22:56:42 +1000 | [diff] [blame] | 173 | |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 174 | if (ename->length < offset+name->length) |
Damien Miller | 134350c | 2003-09-02 22:56:42 +1000 | [diff] [blame] | 175 | return GSS_S_FAILURE; |
| 176 | |
Damien Miller | a0c4ad2 | 2003-09-02 22:56:18 +1000 | [diff] [blame] | 177 | name->value = xmalloc(name->length+1); |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 178 | memcpy(name->value,tok+offset,name->length); |
Damien Miller | a0c4ad2 | 2003-09-02 22:56:18 +1000 | [diff] [blame] | 179 | ((char *)name->value)[name->length] = 0; |
| 180 | |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 181 | return GSS_S_COMPLETE; |
Damien Miller | 134350c | 2003-09-02 22:56:42 +1000 | [diff] [blame] | 182 | } |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 183 | |
| 184 | /* Extract the client details from a given context. This can only reliably |
| 185 | * be called once for a context */ |
| 186 | |
Damien Miller | 9fac263 | 2005-11-05 15:03:48 +1100 | [diff] [blame] | 187 | /* Privileged (called from accept_secure_ctx) */ |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 188 | OM_uint32 |
| 189 | ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client) |
| 190 | { |
| 191 | int i = 0; |
| 192 | |
| 193 | gss_buffer_desc ename; |
Damien Miller | 134350c | 2003-09-02 22:56:42 +1000 | [diff] [blame] | 194 | |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 195 | client->mech = NULL; |
| 196 | |
| 197 | while (supported_mechs[i]->name != NULL) { |
| 198 | if (supported_mechs[i]->oid.length == ctx->oid->length && |
| 199 | (memcmp(supported_mechs[i]->oid.elements, |
| 200 | ctx->oid->elements, ctx->oid->length) == 0)) |
| 201 | client->mech = supported_mechs[i]; |
| 202 | i++; |
| 203 | } |
| 204 | |
Damien Miller | 134350c | 2003-09-02 22:56:42 +1000 | [diff] [blame] | 205 | if (client->mech == NULL) |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 206 | return GSS_S_FAILURE; |
Damien Miller | 134350c | 2003-09-02 22:56:42 +1000 | [diff] [blame] | 207 | |
| 208 | if ((ctx->major = gss_display_name(&ctx->minor, ctx->client, |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 209 | &client->displayname, NULL))) { |
Damien Miller | 134350c | 2003-09-02 22:56:42 +1000 | [diff] [blame] | 210 | ssh_gssapi_error(ctx); |
| 211 | return (ctx->major); |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 212 | } |
Damien Miller | 134350c | 2003-09-02 22:56:42 +1000 | [diff] [blame] | 213 | |
| 214 | if ((ctx->major = gss_export_name(&ctx->minor, ctx->client, |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 215 | &ename))) { |
| 216 | ssh_gssapi_error(ctx); |
| 217 | return (ctx->major); |
| 218 | } |
Damien Miller | 134350c | 2003-09-02 22:56:42 +1000 | [diff] [blame] | 219 | |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 220 | if ((ctx->major = ssh_gssapi_parse_ename(ctx,&ename, |
| 221 | &client->exportedname))) { |
| 222 | return (ctx->major); |
| 223 | } |
| 224 | |
| 225 | /* We can't copy this structure, so we just move the pointer to it */ |
| 226 | client->creds = ctx->client_creds; |
| 227 | ctx->client_creds = GSS_C_NO_CREDENTIAL; |
| 228 | return (ctx->major); |
| 229 | } |
| 230 | |
Darren Tucker | 3e33cec | 2003-10-02 16:12:36 +1000 | [diff] [blame] | 231 | /* As user - called on fatal/exit */ |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 232 | void |
Darren Tucker | 3e33cec | 2003-10-02 16:12:36 +1000 | [diff] [blame] | 233 | ssh_gssapi_cleanup_creds(void) |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 234 | { |
| 235 | if (gssapi_client.store.filename != NULL) { |
| 236 | /* Unlink probably isn't sufficient */ |
| 237 | debug("removing gssapi cred file\"%s\"", gssapi_client.store.filename); |
| 238 | unlink(gssapi_client.store.filename); |
| 239 | } |
| 240 | } |
| 241 | |
| 242 | /* As user */ |
| 243 | void |
| 244 | ssh_gssapi_storecreds(void) |
| 245 | { |
| 246 | if (gssapi_client.mech && gssapi_client.mech->storecreds) { |
| 247 | (*gssapi_client.mech->storecreds)(&gssapi_client); |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 248 | } else |
| 249 | debug("ssh_gssapi_storecreds: Not a GSSAPI mechanism"); |
| 250 | } |
| 251 | |
| 252 | /* This allows GSSAPI methods to do things to the childs environment based |
| 253 | * on the passed authentication process and credentials. |
| 254 | */ |
| 255 | /* As user */ |
| 256 | void |
| 257 | ssh_gssapi_do_child(char ***envp, u_int *envsizep) |
| 258 | { |
| 259 | |
| 260 | if (gssapi_client.store.envvar != NULL && |
| 261 | gssapi_client.store.envval != NULL) { |
| 262 | |
| 263 | debug("Setting %s to %s", gssapi_client.store.envvar, |
| 264 | gssapi_client.store.envval); |
| 265 | child_set_env(envp, envsizep, gssapi_client.store.envvar, |
Damien Miller | 0dc1bef | 2005-07-17 17:22:45 +1000 | [diff] [blame] | 266 | gssapi_client.store.envval); |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 267 | } |
| 268 | } |
| 269 | |
Darren Tucker | 8813bbb | 2005-10-03 18:17:02 +1000 | [diff] [blame] | 270 | /* Privileged */ |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 271 | int |
| 272 | ssh_gssapi_userok(char *user) |
| 273 | { |
Damien Miller | da9984f | 2005-08-31 19:46:26 +1000 | [diff] [blame] | 274 | OM_uint32 lmin; |
| 275 | |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 276 | if (gssapi_client.exportedname.length == 0 || |
| 277 | gssapi_client.exportedname.value == NULL) { |
| 278 | debug("No suitable client data"); |
| 279 | return 0; |
| 280 | } |
| 281 | if (gssapi_client.mech && gssapi_client.mech->userok) |
Damien Miller | da9984f | 2005-08-31 19:46:26 +1000 | [diff] [blame] | 282 | if ((*gssapi_client.mech->userok)(&gssapi_client, user)) |
| 283 | return 1; |
| 284 | else { |
| 285 | /* Destroy delegated credentials if userok fails */ |
| 286 | gss_release_buffer(&lmin, &gssapi_client.displayname); |
| 287 | gss_release_buffer(&lmin, &gssapi_client.exportedname); |
| 288 | gss_release_cred(&lmin, &gssapi_client.creds); |
| 289 | memset(&gssapi_client, 0, sizeof(ssh_gssapi_client)); |
| 290 | return 0; |
| 291 | } |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 292 | else |
| 293 | debug("ssh_gssapi_userok: Unknown GSSAPI mechanism"); |
| 294 | return (0); |
| 295 | } |
| 296 | |
Damien Miller | 9fac263 | 2005-11-05 15:03:48 +1100 | [diff] [blame] | 297 | /* Privileged */ |
Damien Miller | 0425d40 | 2003-11-17 22:18:21 +1100 | [diff] [blame] | 298 | OM_uint32 |
| 299 | ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic) |
| 300 | { |
| 301 | ctx->major = gss_verify_mic(&ctx->minor, ctx->context, |
| 302 | gssbuf, gssmic, NULL); |
| 303 | |
| 304 | return (ctx->major); |
| 305 | } |
| 306 | |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 307 | #endif |