1 /*
2 * Copyright (c) 2001 Proofpoint, Inc. and its suppliers.
3 * All rights reserved.
4 *
5 * By using this file, you agree to the terms and conditions set
6 * forth in the LICENSE file which can be found at the top level of
7 * the sendmail distribution.
8 *
9 */
10
11 /*
12 ** This program checks to see if your version of setgid works.
13 ** Compile it, make it set-group-ID guest, and run it as yourself (NOT as
14 ** root and not as member of the group guest).
15 **
16 ** Compilation is trivial -- just "cc t_dropgid.c". Make it set-group-ID
17 ** guest and then execute it as a non-root user.
18 */
19
20 #include <sys/types.h>
21 #include <unistd.h>
22 #include <stdio.h>
23 #include <stdlib.h>
24
25 #ifndef lint
26 static char id[] = "@(#)$Id: t_dropgid.c,v 1.7 2013-11-22 20:52:01 ca Exp $";
27 #endif
28
29 static void
printgids(str,r,e)30 printgids(str, r, e)
31 char *str;
32 gid_t r, e;
33 {
34 printf("%s (should be %d/%d): r/egid=%d/%d\n", str, (int) r, (int) e,
35 (int) getgid(), (int) getegid());
36 }
37
38 /* define only one of these */
39 #if HASSETEGID
40 # define SETGIDCALL "setegid"
41 #endif
42 #if HASSETREGID
43 # define SETGIDCALL "setregid"
44 #endif
45 #if HASSETRESGID
46 # define SETGIDCALL "setresgid"
47 #endif
48
49 #ifndef SETGIDCALL
50 # define SETGIDCALL "setgid"
51 #endif
52
53 int
main(argc,argv)54 main(argc, argv)
55 int argc;
56 char **argv;
57 {
58 int fail = 0;
59 int res;
60 gid_t realgid = getgid();
61 gid_t effgid = getegid();
62 char *prg = argv[0];
63
64 printgids("initial gids", realgid, effgid);
65
66 if (effgid == realgid)
67 {
68 printf("SETUP ERROR: re-run set-group-ID guest\n");
69 printf("Use chgrp(1) and chmod(1)\n");
70 printf("For example, do this as root ");
71 printf("(nobody is the name of a group in this example):\n");
72 printf("# chgrp nobody %s\n", prg);
73 printf("# chmod g+s nobody %s\n", prg);
74 exit(1);
75 }
76
77 #if HASSETREGID
78 res = setregid(realgid, realgid);
79 printf("setregid(%d)=%d %s\n", (int) realgid, res,
80 res < 0 ? "failure" : "ok");
81 printgids("after setregid()", realgid, realgid);
82 #endif /* HASSETREGID */
83 #if HASSETRESGID
84 res = setresgid(realgid, realgid, realgid);
85 printf("setresgid(%d)=%d %s\n", (int) realgid, res,
86 res < 0 ? "failure" : "ok");
87 printgids("after setresgid()", realgid, realgid);
88 #endif /* HASSETRESGID */
89 #if HASSETEGID
90 res = setegid(realgid);
91 printf("setegid(%d)=%d %s\n", (int) realgid, res,
92 res < 0 ? "failure" : "ok");
93 printgids("after setegid()", realgid, realgid);
94 #endif /* HASSETEGID */
95 res = setgid(realgid);
96 printf("setgid(%d)=%d %s\n", (int) realgid, res,
97 res < 0 ? "failure" : "ok");
98 printgids("after setgid()", realgid, realgid);
99
100 if (getegid() != realgid)
101 {
102 fail++;
103 printf("MAYDAY! Wrong effective gid\n");
104 }
105
106 if (getgid() != realgid)
107 {
108 fail++;
109 printf("MAYDAY! Wrong real gid\n");
110 }
111
112 /* do activity here */
113 if (setgid(effgid) == 0)
114 {
115 fail++;
116 printf("MAYDAY! setgid(%d) succeeded (should have failed)\n",
117 effgid);
118 }
119 else
120 {
121 printf("setgid(%d) failed (this is correct)\n", effgid);
122 }
123 printgids("after setgid() to egid", realgid, realgid);
124
125 if (getegid() != realgid)
126 {
127 fail++;
128 printf("MAYDAY! Wrong effective gid\n");
129 }
130 if (getgid() != realgid)
131 {
132 fail++;
133 printf("MAYDAY! Wrong real gid\n");
134 }
135 printf("\n");
136
137 if (fail > 0)
138 {
139 printf("\nThis system cannot use %s to give up set-group-ID rights\n",
140 SETGIDCALL);
141 #if !HASSETEGID
142 printf("Maybe compile with -DHASSETEGID and try again\n");
143 #endif
144 #if !HASSETREGID
145 printf("Maybe compile with -DHASSETREGID and try again\n");
146 #endif
147 #if !HASSETRESGID
148 printf("Maybe compile with -DHASSETRESGID and try again\n");
149 #endif
150 exit(1);
151 }
152
153 printf("\nIt is possible to use %s on this system\n", SETGIDCALL);
154 exit(0);
155 }
156