aboutsummaryrefslogtreecommitdiff
path: root/lib/userprivs.c
blob: adaaaafcf4aada4043bcfce269deed0c54d63b54 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
/* This file is part of GNU Dico.
   Copyright (C) 2007-2008, 2010, 2012 Sergey Poznyakoff

   GNU Dico is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3, or (at your option)
   any later version.

   GNU Dico is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with GNU Dico.  If not, see <http://www.gnu.org/licenses/>. */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <grp.h>
#include <errno.h>
#include <xalloc.h>
#include <xdico.h>
#include <libi18n.h>

/* Switch to the given UID/GID */
int
switch_to_privs (uid_t uid, gid_t gid, dico_list_t retain_groups)
{
    int rc = 0;
    gid_t *emptygidset;
    size_t size = 1, j = 1;
    dico_iterator_t itr;
    void *gp;

    _dico_libi18n_init();
    
    if (uid == 0) {
	dico_log(L_ERR, 0, _("Refusing to run as root"));
	return 1;
    }

    /* Create a list of supplementary groups */
    size = dico_list_count(retain_groups);
    size++;
    emptygidset = xcalloc(size, sizeof emptygidset[0]);
    emptygidset[0] = gid ? gid : getegid();

    itr = dico_list_iterator(retain_groups);
    for (gp = dico_iterator_first(itr); gp;
	 gp = dico_iterator_next(itr)) 
	emptygidset[j++] = (gid_t) gp;
    dico_iterator_destroy(&itr);
    
    /* Reset group permissions */
    if (geteuid() == 0 && setgroups(j, emptygidset)) {
	dico_log(L_ERR, errno, _("setgroups(1, %lu) failed"),
		 (unsigned long) emptygidset[0]);
	rc = 1;
    }
    free(emptygidset);
	
    /* Switch to the user's gid. On some OSes the effective gid must
       be reset first */

#if defined(HAVE_SETEGID)
    if ((rc = setegid(gid)) < 0)
	dico_log(L_ERR, errno, _("setegid(%lu) failed"),
		 (unsigned long) gid);
#elif defined(HAVE_SETREGID)
    if ((rc = setregid(gid, gid)) < 0)
	dico_log(L_ERR, errno, _("setregid(%lu,%lu) failed"),
		 (unsigned long) gid, (unsigned long) gid);
#elif defined(HAVE_SETRESGID)
    if ((rc = setresgid(gid, gid, gid)) < 0)
	dico_log(L_ERR, errno, _("setresgid(%lu,%lu,%lu) failed"),
		 (unsigned long) gid,
		 (unsigned long) gid,
		 (unsigned long) gid);
#endif

    if (rc == 0 && gid != 0) {
	if ((rc = setgid(gid)) < 0 && getegid() != gid) 
	    dico_log(L_ERR, errno, _("setgid(%lu) failed"),
		     (unsigned long) gid);
	if (rc == 0 && getegid() != gid) {
	    dico_log(L_ERR, errno, _("Cannot set effective gid to %lu"),
		     (unsigned long) gid);
	    rc = 1;
	}
    }

    /* Now reset uid */
    if (rc == 0 && uid != 0) {
	uid_t euid;
	
	if (setuid(uid)
	    || geteuid() != uid
	    || (getuid() != uid
		&& (geteuid() == 0 || getuid() == 0))) {
			
#if defined(HAVE_SETREUID)
	    if (geteuid() != uid) {
		if (setreuid(uid, -1) < 0) { 
		    dico_log(L_ERR, errno, _("setreuid(%lu,-1) failed"),
			     (unsigned long) uid);
		    rc = 1;
		}
		if (setuid(uid) < 0) {
		    dico_log(L_ERR, errno, _("second setuid(%lu) failed"),
			     (unsigned long) uid);
		    rc = 1;
		}
	    } else
#endif
		{
		    dico_log(L_ERR, errno, _("setuid(%lu) failed"),
			     (unsigned long) uid);
		    rc = 1;
		}
	}
	
	euid = geteuid();
	if (uid != 0 && setuid(0) == 0) {
	    dico_log(L_ERR, 0, _("seteuid(0) succeeded when it should not"));
	    rc = 1;
	} else if (uid != euid && setuid(euid) == 0) {
	    dico_log(L_ERR, 0, _("Cannot drop non-root setuid privileges"));
	    rc = 1;
	}
	
    }

    return rc;
}


Return to:

Send suggestions and report system problems to the System administrator.