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  */
   6
   7 #include "includes.h"
   8 RCSID("$OpenBSD: auth-krb5.c,v 1.6 2002/03/04 17:27:39 stevesk Exp $");
   9
  10 #include "ssh.h"
  11 #include "ssh1.h"
  12 #include "packet.h"
  13 #include "xmalloc.h"
  14 #include "log.h"
  15 #include "servconf.h"
  16 #include "uidswap.h"
  17 #include "auth.h"
  18
  19 #ifdef KRB5
  20 #include <krb5.h>
  21
  22 extern ServerOptions     options;
  23
  24 static int
  25 krb5_init(void *context)
  26 {
  27         Authctxt *authctxt = (Authctxt *)context;
  28         krb5_error_code problem;
  29         static int cleanup_registered = 0;
  30
  31         if (authctxt->krb5_ctx == NULL) {
  32                 problem = krb5_init_context(&authctxt->krb5_ctx);
  33                 if (problem)
  34                         return (problem);
  35                 krb5_init_ets(authctxt->krb5_ctx);
  36         }
  37         if (!cleanup_registered) {
  38                 fatal_add_cleanup(krb5_cleanup_proc, authctxt);
  39                 cleanup_registered = 1;
  40         }
  41         return (0);
  42 }
  43
  44 /*
  45  * Try krb5 authentication. server_user is passed for logging purposes
  46  * only, in auth is received ticket, in client is returned principal
  47  * from the ticket
  48  */
  49 int
  50 auth_krb5(Authctxt *authctxt, krb5_data *auth, char **client)
  51 {
  52         krb5_error_code problem;
  53         krb5_principal server;
  54         krb5_data reply;
  55         krb5_ticket *ticket;
  56         int fd, ret;
  57
  58         ret = 0;
  59         server = NULL;
  60         ticket = NULL;
  61         reply.length = 0;
  62
  63         problem = krb5_init(authctxt);
  64         if (problem)
  65                 goto err;
  66
  67         problem = krb5_auth_con_init(authctxt->krb5_ctx,
  68             &authctxt->krb5_auth_ctx);
  69         if (problem)
  70                 goto err;
  71
  72         fd = packet_get_connection_in();
  73         problem = krb5_auth_con_setaddrs_from_fd(authctxt->krb5_ctx,
  74             authctxt->krb5_auth_ctx, &fd);
  75         if (problem)
  76                 goto err;
  77
  78         problem = krb5_sname_to_principal(authctxt->krb5_ctx,  NULL, NULL ,
  79             KRB5_NT_SRV_HST, &server);
  80         if (problem)
  81                 goto err;
  82
  83         problem = krb5_rd_req(authctxt->krb5_ctx, &authctxt->krb5_auth_ctx,
  84             auth, server, NULL, NULL, &ticket);
  85         if (problem)
  86                 goto err;
  87
  88         problem = krb5_copy_principal(authctxt->krb5_ctx, ticket->client,
  89             &authctxt->krb5_user);
  90         if (problem)
  91                 goto err;
  92
  93         /* if client wants mutual auth */
  94         problem = krb5_mk_rep(authctxt->krb5_ctx, authctxt->krb5_auth_ctx,
  95             &reply);
  96         if (problem)
  97                 goto err;
  98
  99         /* Check .k5login authorization now. */
 100         if (!krb5_kuserok(authctxt->krb5_ctx, authctxt->krb5_user,
 101             authctxt->pw->pw_name))
 102                 goto err;
 103
 104         if (client)
 105                 krb5_unparse_name(authctxt->krb5_ctx, authctxt->krb5_user,
 106                     client);
 107
 108         packet_start(SSH_SMSG_AUTH_KERBEROS_RESPONSE);
 109         packet_put_string((char *) reply.data, reply.length);
 110         packet_send();
 111         packet_write_wait();
 112
 113         ret = 1;
 114  err:
 115         if (server)
 116                 krb5_free_principal(authctxt->krb5_ctx, server);
 117         if (ticket)
 118                 krb5_free_ticket(authctxt->krb5_ctx, ticket);
 119         if (reply.length)
 120                 xfree(reply.data);
 121
 122         if (problem) {
 123                 if (authctxt->krb5_ctx != NULL)
 124                         debug("Kerberos v5 authentication failed: %s",
 125                             krb5_get_err_text(authctxt->krb5_ctx, problem));
 126                 else
 127                         debug("Kerberos v5 authentication failed: %d",
 128                             problem);
 129         }
 130
 131         return (ret);
 132 }
 133
 134 int
 135 auth_krb5_tgt(Authctxt *authctxt, krb5_data *tgt)
 136 {
 137         krb5_error_code problem;
 138         krb5_ccache ccache = NULL;
 139         char *pname;
 140
 141         if (authctxt->pw == NULL || authctxt->krb5_user == NULL)
 142                 return (0);
 143
 144         temporarily_use_uid(authctxt->pw);
 145
 146         problem = krb5_cc_gen_new(authctxt->krb5_ctx, &krb5_fcc_ops, &ccache);
 147         if (problem)
 148                 goto fail;
 149
 150         problem = krb5_cc_initialize(authctxt->krb5_ctx, ccache,
 151             authctxt->krb5_user);
 152         if (problem)
 153                 goto fail;
 154
 155         problem = krb5_rd_cred2(authctxt->krb5_ctx, authctxt->krb5_auth_ctx,
 156             ccache, tgt);
 157         if (problem)
 158                 goto fail;
 159
 160         authctxt->krb5_fwd_ccache = ccache;
 161         ccache = NULL;
 162
 163         authctxt->krb5_ticket_file = (char *)krb5_cc_get_name(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
 164
 165         problem = krb5_unparse_name(authctxt->krb5_ctx, authctxt->krb5_user,
 166             &pname);
 167         if (problem)
 168                 goto fail;
 169
 170         debug("Kerberos v5 TGT accepted (%s)", pname);
 171
 172         restore_uid();
 173
 174         return (1);
 175
 176  fail:
 177         if (problem)
 178                 debug("Kerberos v5 TGT passing failed: %s",
 179                     krb5_get_err_text(authctxt->krb5_ctx, problem));
 180         if (ccache)
 181                 krb5_cc_destroy(authctxt->krb5_ctx, ccache);
 182
 183         restore_uid();
 184
 185         return (0);
 186 }
 187
 188 int
 189 auth_krb5_password(Authctxt *authctxt, const char *password)
 190 {
 191         krb5_error_code problem;
 192
 193         if (authctxt->pw == NULL)
 194                 return (0);
 195
 196         temporarily_use_uid(authctxt->pw);
 197
 198         problem = krb5_init(authctxt);
 199         if (problem)
 200                 goto out;
 201
 202         problem = krb5_parse_name(authctxt->krb5_ctx, authctxt->pw->pw_name,
 203                     &authctxt->krb5_user);
 204         if (problem)
 205                 goto out;
 206
 207         problem = krb5_cc_gen_new(authctxt->krb5_ctx, &krb5_mcc_ops,
 208             &authctxt->krb5_fwd_ccache);
 209         if (problem)
 210                 goto out;
 211
 212         problem = krb5_cc_initialize(authctxt->krb5_ctx,
 213             authctxt->krb5_fwd_ccache, authctxt->krb5_user);
 214         if (problem)
 215                 goto out;
 216
 217         restore_uid();
 218         problem = krb5_verify_user(authctxt->krb5_ctx, authctxt->krb5_user,
 219             authctxt->krb5_fwd_ccache, password, 1, NULL);
 220         temporarily_use_uid(authctxt->pw);
 221
 222         if (problem)
 223                 goto out;
 224
 225         authctxt->krb5_ticket_file = (char *)krb5_cc_get_name(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
 226
 227  out:
 228         restore_uid();
 229
 230         if (problem) {
 231                 if (authctxt->krb5_ctx != NULL)
 232                         debug("Kerberos password authentication failed: %s",
 233                             krb5_get_err_text(authctxt->krb5_ctx, problem));
 234                 else
 235                         debug("Kerberos password authentication failed: %d",
 236                             problem);
 237
 238                 krb5_cleanup_proc(authctxt);
 239
 240                 if (options.kerberos_or_local_passwd)
 241                         return (-1);
 242                 else
 243                         return (0);
 244         }
 245         return (1);
 246 }
 247
 248 void
 249 krb5_cleanup_proc(void *context)
 250 {
 251         Authctxt *authctxt = (Authctxt *)context;
 252
 253         debug("krb5_cleanup_proc called");
 254         if (authctxt->krb5_fwd_ccache) {
 255                 krb5_cc_destroy(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
 256                 authctxt->krb5_fwd_ccache = NULL;
 257         }
 258         if (authctxt->krb5_user) {
 259                 krb5_free_principal(authctxt->krb5_ctx, authctxt->krb5_user);
 260                 authctxt->krb5_user = NULL;
 261         }
 262         if (authctxt->krb5_auth_ctx) {
 263                 krb5_auth_con_free(authctxt->krb5_ctx,
 264                     authctxt->krb5_auth_ctx);
 265                 authctxt->krb5_auth_ctx = NULL;
 266         }
 267         if (authctxt->krb5_ctx) {
 268                 krb5_free_context(authctxt->krb5_ctx);
 269                 authctxt->krb5_ctx = NULL;
 270         }
 271 }
 272
 273 #endif /* KRB5 */