1 /*
2  * Copyright (c) 1997 - 2001 Kungliga Tekniska H�gskolan
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 RCSID("$Id: get_default_principal.c 14870 2005-04-20 20:53:29Z lha $");
37 
38 /*
39  * Try to find out what's a reasonable default principal.
40  */
41 
42 static const char*
43 get_env_user(void)
44 {
45     const char *user = getenv("USER");
46     if(user == NULL)
47 	user = getenv("LOGNAME");
48     if(user == NULL)
49 	user = getenv("USERNAME");
50     return user;
51 }
52 
53 /*
54  * Will only use operating-system dependant operation to get the
55  * default principal, for use of functions that in ccache layer to
56  * avoid recursive calls.
57  */
58 
59 krb5_error_code
60 _krb5_get_default_principal_local (krb5_context context,
61 				   krb5_principal *princ)
62 {
63     krb5_error_code ret;
64     const char *user;
65     uid_t uid;
66 
67     *princ = NULL;
68 
69     uid = getuid();
70     if(uid == 0) {
71 	user = getlogin();
72 	if(user == NULL)
73 	    user = get_env_user();
74 	if(user != NULL && strcmp(user, "root") != 0)
75 	    ret = krb5_make_principal(context, princ, NULL, user, "root", NULL);
76 	else
77 	    ret = krb5_make_principal(context, princ, NULL, "root", NULL);
78     } else {
79 	struct passwd *pw = getpwuid(uid);
80 	if(pw != NULL)
81 	    user = pw->pw_name;
82 	else {
83 	    user = get_env_user();
84 	    if(user == NULL)
85 		user = getlogin();
86 	}
87 	if(user == NULL) {
88 	    krb5_set_error_string(context,
89 				  "unable to figure out current principal");
90 	    return ENOTTY; /* XXX */
91 	}
92 	ret = krb5_make_principal(context, princ, NULL, user, NULL);
93     }
94     return ret;
95 }
96 
97 krb5_error_code KRB5_LIB_FUNCTION
98 krb5_get_default_principal (krb5_context context,
99 			    krb5_principal *princ)
100 {
101     krb5_error_code ret;
102     krb5_ccache id;
103 
104     *princ = NULL;
105 
106     ret = krb5_cc_default (context, &id);
107     if (ret == 0) {
108 	ret = krb5_cc_get_principal (context, id, princ);
109 	krb5_cc_close (context, id);
110 	if (ret == 0)
111 	    return 0;
112     }
113 
114     return _krb5_get_default_principal_local(context, princ);
115 }
116