auth-krb5.c

   1 /*
   2  *    Kerberos v5 authentication and ticket-passing routines.
   3  *
   4  * $FreeBSD: src/crypto/openssh/auth-krb5.c,v 1.6 2001/02/13 16:58:04 assar Exp $
   5  * $OpenBSD: auth-krb5.c,v 1.5 2002/02/15 23:54:10 markus Exp $
   6  */
   7
   8 #include "includes.h"
   9 #include "ssh.h"
  10 #include "ssh1.h"
  11 #include "packet.h"
  12 #include "xmalloc.h"
  13 #include "log.h"
  14 #include "servconf.h"
  15 #include "uidswap.h"
  16 #include "auth.h"
  17
  18 #ifdef KRB5
  19 #include <krb5.h>
  20
  21 extern ServerOptions     options;
  22
  23 static int
  24 krb5_init(void *context)
  25 {
  26         Authctxt *authctxt = (Authctxt *)context;
  27         krb5_error_code problem;
  28         static int cleanup_registered = 0;
  29
  30         if (authctxt->krb5_ctx == NULL) {
  31                 problem = krb5_init_context(&authctxt->krb5_ctx);
  32                 if (problem)
  33                         return (problem);
  34                 krb5_init_ets(authctxt->krb5_ctx);
  35         }
  36         if (!cleanup_registered) {
  37                 fatal_add_cleanup(krb5_cleanup_proc, authctxt);
  38                 cleanup_registered = 1;
  39         }
  40         return (0);
  41 }
  42
  43 /*
  44  * Try krb5 authentication. server_user is passed for logging purposes
  45  * only, in auth is received ticket, in client is returned principal
  46  * from the ticket
  47  */
  48 int
  49 auth_krb5(Authctxt *authctxt, krb5_data *auth, char **client)
  50 {
  51         krb5_error_code problem;
  52         krb5_principal server;
  53         krb5_data reply;
  54         krb5_ticket *ticket;
  55         int fd, ret;
  56
  57         ret = 0;
  58         server = NULL;
  59         ticket = NULL;
  60         reply.length = 0;
  61
  62         problem = krb5_init(authctxt);
  63         if (problem)
  64                 goto err;
  65
  66         problem = krb5_auth_con_init(authctxt->krb5_ctx,
  67             &authctxt->krb5_auth_ctx);
  68         if (problem)
  69                 goto err;
  70
  71         fd = packet_get_connection_in();
  72         problem = krb5_auth_con_setaddrs_from_fd(authctxt->krb5_ctx,
  73             authctxt->krb5_auth_ctx, &fd);
  74         if (problem)
  75                 goto err;
  76
  77         problem = krb5_sname_to_principal(authctxt->krb5_ctx,  NULL, NULL ,
  78             KRB5_NT_SRV_HST, &server);
  79         if (problem)
  80                 goto err;
  81
  82         problem = krb5_rd_req(authctxt->krb5_ctx, &authctxt->krb5_auth_ctx,
  83             auth, server, NULL, NULL, &ticket);
  84         if (problem)
  85                 goto err;
  86
  87         problem = krb5_copy_principal(authctxt->krb5_ctx, ticket->client,
  88             &authctxt->krb5_user);
  89         if (problem)
  90                 goto err;
  91
  92         /* if client wants mutual auth */
  93         problem = krb5_mk_rep(authctxt->krb5_ctx, authctxt->krb5_auth_ctx,
  94             &reply);
  95         if (problem)
  96                 goto err;
  97
  98         /* Check .k5login authorization now. */
  99         if (!krb5_kuserok(authctxt->krb5_ctx, authctxt->krb5_user,
 100             authctxt->pw->pw_name))
 101                 goto err;
 102
 103         if (client)
 104                 krb5_unparse_name(authctxt->krb5_ctx, authctxt->krb5_user,
 105                     client);
 106
 107         packet_start(SSH_SMSG_AUTH_KERBEROS_RESPONSE);
 108         packet_put_string((char *) reply.data, reply.length);
 109         packet_send();
 110         packet_write_wait();
 111
 112         ret = 1;
 113  err:
 114         if (server)
 115                 krb5_free_principal(authctxt->krb5_ctx, server);
 116         if (ticket)
 117                 krb5_free_ticket(authctxt->krb5_ctx, ticket);
 118         if (reply.length)
 119                 xfree(reply.data);
 120
 121         if (problem) {
 122                 if (authctxt->krb5_ctx != NULL)
 123                         debug("Kerberos v5 authentication failed: %s",
 124                             krb5_get_err_text(authctxt->krb5_ctx, problem));
 125                 else
 126                         debug("Kerberos v5 authentication failed: %d",
 127                             problem);
 128         }
 129
 130         return (ret);
 131 }
 132
 133 int
 134 auth_krb5_tgt(Authctxt *authctxt, krb5_data *tgt)
 135 {
 136         krb5_error_code problem;
 137         krb5_ccache ccache = NULL;
 138         char *pname;
 139
 140         if (authctxt->pw == NULL || authctxt->krb5_user == NULL)
 141                 return (0);
 142
 143         temporarily_use_uid(authctxt->pw);
 144
 145         problem = krb5_cc_gen_new(authctxt->krb5_ctx, &krb5_fcc_ops, &ccache);
 146         if (problem)
 147                 goto fail;
 148
 149         problem = krb5_cc_initialize(authctxt->krb5_ctx, ccache,
 150             authctxt->krb5_user);
 151         if (problem)
 152                 goto fail;
 153
 154         problem = krb5_rd_cred2(authctxt->krb5_ctx, authctxt->krb5_auth_ctx,
 155             ccache, tgt);
 156         if (problem)
 157                 goto fail;
 158
 159         authctxt->krb5_fwd_ccache = ccache;
 160         ccache = NULL;
 161
 162         authctxt->krb5_ticket_file = (char *)krb5_cc_get_name(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
 163
 164         problem = krb5_unparse_name(authctxt->krb5_ctx, authctxt->krb5_user,
 165             &pname);
 166         if (problem)
 167                 goto fail;
 168
 169         debug("Kerberos v5 TGT accepted (%s)", pname);
 170
 171         restore_uid();
 172
 173         return (1);
 174
 175  fail:
 176         if (problem)
 177                 debug("Kerberos v5 TGT passing failed: %s",
 178                     krb5_get_err_text(authctxt->krb5_ctx, problem));
 179         if (ccache)
 180                 krb5_cc_destroy(authctxt->krb5_ctx, ccache);
 181
 182         restore_uid();
 183
 184         return (0);
 185 }
 186
 187 int
 188 auth_krb5_password(Authctxt *authctxt, const char *password)
 189 {
 190         krb5_error_code problem;
 191
 192         if (authctxt->pw == NULL)
 193                 return (0);
 194
 195         temporarily_use_uid(authctxt->pw);
 196
 197         problem = krb5_init(authctxt);
 198         if (problem)
 199                 goto out;
 200
 201         problem = krb5_parse_name(authctxt->krb5_ctx, authctxt->pw->pw_name,
 202                     &authctxt->krb5_user);
 203         if (problem)
 204                 goto out;
 205
 206         problem = krb5_cc_gen_new(authctxt->krb5_ctx, &krb5_mcc_ops,
 207             &authctxt->krb5_fwd_ccache);
 208         if (problem)
 209                 goto out;
 210
 211         problem = krb5_cc_initialize(authctxt->krb5_ctx,
 212             authctxt->krb5_fwd_ccache, authctxt->krb5_user);
 213         if (problem)
 214                 goto out;
 215
 216         restore_uid();
 217         problem = krb5_verify_user(authctxt->krb5_ctx, authctxt->krb5_user,
 218             authctxt->krb5_fwd_ccache, password, 1, NULL);
 219         temporarily_use_uid(authctxt->pw);
 220
 221         if (problem)
 222                 goto out;
 223
 224         authctxt->krb5_ticket_file = (char *)krb5_cc_get_name(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
 225
 226  out:
 227         restore_uid();
 228
 229         if (problem) {
 230                 if (authctxt->krb5_ctx != NULL)
 231                         debug("Kerberos password authentication failed: %s",
 232                             krb5_get_err_text(authctxt->krb5_ctx, problem));
 233                 else
 234                         debug("Kerberos password authentication failed: %d",
 235                             problem);
 236
 237                 krb5_cleanup_proc(authctxt);
 238
 239                 if (options.kerberos_or_local_passwd)
 240                         return (-1);
 241                 else
 242                         return (0);
 243         }
 244         return (1);
 245 }
 246
 247 void
 248 krb5_cleanup_proc(void *context)
 249 {
 250         Authctxt *authctxt = (Authctxt *)context;
 251
 252         debug("krb5_cleanup_proc called");
 253         if (authctxt->krb5_fwd_ccache) {
 254                 krb5_cc_destroy(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
 255                 authctxt->krb5_fwd_ccache = NULL;
 256         }
 257         if (authctxt->krb5_user) {
 258                 krb5_free_principal(authctxt->krb5_ctx, authctxt->krb5_user);
 259                 authctxt->krb5_user = NULL;
 260         }
 261         if (authctxt->krb5_auth_ctx) {
 262                 krb5_auth_con_free(authctxt->krb5_ctx,
 263                     authctxt->krb5_auth_ctx);
 264                 authctxt->krb5_auth_ctx = NULL;
 265         }
 266         if (authctxt->krb5_ctx) {
 267                 krb5_free_context(authctxt->krb5_ctx);
 268                 authctxt->krb5_ctx = NULL;
 269         }
 270 }
 271
 272 #endif /* KRB5 */