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 1.1 2001/06/26 16:15:23 dugsong 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;
  56
  57         server = NULL;
  58         ticket = NULL;
  59         reply.length = 0;
  60
  61         problem = krb5_init(authctxt);
  62         if (problem)
  63                 goto err;
  64
  65         problem = krb5_auth_con_init(authctxt->krb5_ctx,
  66             &authctxt->krb5_auth_ctx);
  67         if (problem)
  68                 goto err;
  69
  70         fd = packet_get_connection_in();
  71         problem = krb5_auth_con_setaddrs_from_fd(authctxt->krb5_ctx,
  72             authctxt->krb5_auth_ctx, &fd);
  73         if (problem)
  74                 goto err;
  75
  76         problem = krb5_sname_to_principal(authctxt->krb5_ctx,  NULL, NULL ,
  77             KRB5_NT_SRV_HST, &server);
  78         if (problem)
  79                 goto err;
  80
  81         problem = krb5_rd_req(authctxt->krb5_ctx, &authctxt->krb5_auth_ctx,
  82             auth, server, NULL, NULL, &ticket);
  83         if (problem)
  84                 goto err;
  85
  86         problem = krb5_copy_principal(authctxt->krb5_ctx, ticket->client,
  87             &authctxt->krb5_user);
  88         if (problem)
  89                 goto err;
  90
  91         /* if client wants mutual auth */
  92         problem = krb5_mk_rep(authctxt->krb5_ctx, authctxt->krb5_auth_ctx,
  93             &reply);
  94         if (problem)
  95                 goto err;
  96
  97         /* Check .k5login authorization now. */
  98         if (!krb5_kuserok(authctxt->krb5_ctx, authctxt->krb5_user,
  99             authctxt->pw->pw_name))
 100                 goto err;
 101
 102         if (client)
 103                 krb5_unparse_name(authctxt->krb5_ctx, authctxt->krb5_user,
 104                     client);
 105
 106         packet_start(SSH_SMSG_AUTH_KERBEROS_RESPONSE);
 107         packet_put_string((char *) reply.data, reply.length);
 108         packet_send();
 109         packet_write_wait();
 110
 111  err:
 112         if (server)
 113                 krb5_free_principal(authctxt->krb5_ctx, server);
 114         if (ticket)
 115                 krb5_free_ticket(authctxt->krb5_ctx, ticket);
 116         if (reply.length)
 117                 xfree(reply.data);
 118
 119         if (problem) {
 120                 debug("Kerberos v5 authentication failed: %s",
 121                     krb5_get_err_text(authctxt->krb5_ctx, problem));
 122                 return (0);
 123         }
 124         return (1);
 125 }
 126
 127 int
 128 auth_krb5_tgt(Authctxt *authctxt, krb5_data *tgt)
 129 {
 130         krb5_error_code problem;
 131         krb5_ccache ccache = NULL;
 132         char *pname;
 133
 134         if (authctxt->pw == NULL || authctxt->krb5_user == NULL)
 135                 return (0);
 136
 137         temporarily_use_uid(authctxt->pw);
 138
 139         problem = krb5_cc_gen_new(authctxt->krb5_ctx, &krb5_fcc_ops, &ccache);
 140         if (problem)
 141                 goto fail;
 142
 143         problem = krb5_cc_initialize(authctxt->krb5_ctx, ccache,
 144             authctxt->krb5_user);
 145         if (problem)
 146                 goto fail;
 147
 148         problem = krb5_rd_cred2(authctxt->krb5_ctx, authctxt->krb5_auth_ctx,
 149             ccache, tgt);
 150         if (problem)
 151                 goto fail;
 152
 153         authctxt->krb5_fwd_ccache = ccache;
 154         ccache = NULL;
 155
 156         authctxt->krb5_ticket_file = (char *)krb5_cc_get_name(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
 157
 158         problem = krb5_unparse_name(authctxt->krb5_ctx, authctxt->krb5_user,
 159             &pname);
 160         if (problem)
 161                 goto fail;
 162
 163         debug("Kerberos v5 TGT accepted (%s)", pname);
 164
 165         restore_uid();
 166
 167         return (1);
 168
 169  fail:
 170         if (problem)
 171                 debug("Kerberos v5 TGT passing failed: %s",
 172                     krb5_get_err_text(authctxt->krb5_ctx, problem));
 173         if (ccache)
 174                 krb5_cc_destroy(authctxt->krb5_ctx, ccache);
 175
 176         restore_uid();
 177
 178         return (0);
 179 }
 180
 181 int
 182 auth_krb5_password(Authctxt *authctxt, const char *password)
 183 {
 184         krb5_error_code problem;
 185
 186         if (authctxt->pw == NULL)
 187                 return (0);
 188
 189         temporarily_use_uid(authctxt->pw);
 190
 191         problem = krb5_init(authctxt);
 192         if (problem)
 193                 goto out;
 194
 195         problem = krb5_parse_name(authctxt->krb5_ctx, authctxt->pw->pw_name,
 196                     &authctxt->krb5_user);
 197         if (problem)
 198                 goto out;
 199
 200         problem = krb5_cc_gen_new(authctxt->krb5_ctx, &krb5_mcc_ops,
 201             &authctxt->krb5_fwd_ccache);
 202         if (problem)
 203                 goto out;
 204
 205         problem = krb5_cc_initialize(authctxt->krb5_ctx,
 206             authctxt->krb5_fwd_ccache, authctxt->krb5_user);
 207         if (problem)
 208                 goto out;
 209
 210         problem = krb5_verify_user(authctxt->krb5_ctx, authctxt->krb5_user,
 211             authctxt->krb5_fwd_ccache, password, 1, NULL);
 212         if (problem)
 213                 goto out;
 214
 215         authctxt->krb5_ticket_file = (char *)krb5_cc_get_name(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
 216
 217  out:
 218         restore_uid();
 219
 220         if (problem) {
 221                 debug("Kerberos password authentication failed: %s",
 222                     krb5_get_err_text(authctxt->krb5_ctx, problem));
 223
 224                 krb5_cleanup_proc(authctxt);
 225
 226                 if (options.kerberos_or_local_passwd)
 227                         return (-1);
 228                 else
 229                         return (0);
 230         }
 231         return (1);
 232 }
 233
 234 void
 235 krb5_cleanup_proc(void *context)
 236 {
 237         Authctxt *authctxt = (Authctxt *)context;
 238
 239         debug("krb5_cleanup_proc called");
 240         if (authctxt->krb5_fwd_ccache) {
 241                 krb5_cc_destroy(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
 242                 authctxt->krb5_fwd_ccache = NULL;
 243         }
 244         if (authctxt->krb5_user) {
 245                 krb5_free_principal(authctxt->krb5_ctx, authctxt->krb5_user);
 246                 authctxt->krb5_user = NULL;
 247         }
 248         if (authctxt->krb5_auth_ctx) {
 249                 krb5_auth_con_free(authctxt->krb5_ctx,
 250                     authctxt->krb5_auth_ctx);
 251                 authctxt->krb5_auth_ctx = NULL;
 252         }
 253         if (authctxt->krb5_ctx) {
 254                 krb5_free_context(authctxt->krb5_ctx);
 255                 authctxt->krb5_ctx = NULL;
 256         }
 257 }
 258
 259 #endif /* KRB5 */