lib/krb5/get_default_principal.c

   1 /*
   2  * Copyright (c) 1997 - 2001 Kungliga Tekniska Högskolan
   3  * (Royal Institute of Technology, Stockholm, Sweden).
   4  * 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  *
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  *
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  *
  17  * 3. Neither the name of the Institute nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #include "krb5_locl.h"
  35
  36 /*
  37  * Try to find out what's a reasonable default principal.
  38  */
  39
  40 static const char*
  41 get_env_user(void)
  42 {
  43     const char *user = getenv("USER");
  44     if(user == NULL)
  45         user = getenv("LOGNAME");
  46     if(user == NULL)
  47         user = getenv("USERNAME");
  48     return user;
  49 }
  50
  51 /*
  52  * Will only use operating-system dependant operation to get the
  53  * default principal, for use of functions that in ccache layer to
  54  * avoid recursive calls.
  55  */
  56
  57 krb5_error_code
  58 _krb5_get_default_principal_local (krb5_context context,
  59                                    krb5_principal *princ)
  60 {
  61     krb5_error_code ret;
  62     const char *user;
  63     uid_t uid;
  64
  65     *princ = NULL;
  66
  67     uid = getuid();
  68     if(uid == 0) {
  69         user = getlogin();
  70         if(user == NULL)
  71             user = get_env_user();
  72         if(user != NULL && strcmp(user, "root") != 0)
  73             ret = krb5_make_principal(context, princ, NULL, user, "root", NULL);
  74         else
  75             ret = krb5_make_principal(context, princ, NULL, "root", NULL);
  76     } else {
  77         struct passwd *pw = getpwuid(uid);
  78         if(pw != NULL)
  79             user = pw->pw_name;
  80         else {
  81             user = get_env_user();
  82             if(user == NULL)
  83                 user = getlogin();
  84         }
  85         if(user == NULL) {
  86             krb5_set_error_message(context, ENOTTY,
  87                                    N_("unable to figure out current "
  88                                       "principal", ""));
  89             return ENOTTY; /* XXX */
  90         }
  91         ret = krb5_make_principal(context, princ, NULL, user, NULL);
  92     }
  93     return ret;
  94 }
  95
  96 krb5_error_code KRB5_LIB_FUNCTION
  97 krb5_get_default_principal (krb5_context context,
  98                             krb5_principal *princ)
  99 {
 100     krb5_error_code ret;
 101     krb5_ccache id;
 102
 103     *princ = NULL;
 104
 105     ret = krb5_cc_default (context, &id);
 106     if (ret == 0) {
 107         ret = krb5_cc_get_principal (context, id, princ);
 108         krb5_cc_close (context, id);
 109         if (ret == 0)
 110             return 0;
 111     }
 112
 113     return _krb5_get_default_principal_local(context, princ);
 114 }