1 /*
2 * Copyright (c) 2010-2014, Simon Schubert <2@0x2c.org>.
3 * Copyright (c) 2008 The DragonFly Project. All rights reserved.
4 *
5 * This code is derived from software contributed to The DragonFly Project
6 * by Simon Schubert <2@0x2c.org>.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in
16 * the documentation and/or other materials provided with the
17 * distribution.
18 * 3. Neither the name of The DragonFly Project nor the names of its
19 * contributors may be used to endorse or promote products derived
20 * from this software without specific, prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
23 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
24 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
25 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
26 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
27 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
28 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
29 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
30 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
31 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
32 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 */
35
36 /*
37 * This binary is setuid root. Use extreme caution when touching
38 * user-supplied information. Keep the root window as small as possible.
39 */
40
41 #ifdef __FreeBSD__
42 #define USE_CAPSICUM 1
43 #endif
44
45 #include <sys/param.h>
46 #if USE_CAPSICUM
47 #include <sys/capsicum.h>
48 #endif
49 #include <sys/stat.h>
50
51 #include <capsicum_helpers.h>
52 #include <err.h>
53 #include <errno.h>
54 #include <fcntl.h>
55 #include <grp.h>
56 #include <paths.h>
57 #include <pwd.h>
58 #include <stdio.h>
59 #include <string.h>
60 #include <syslog.h>
61 #include <unistd.h>
62
63 #include "dma.h"
64
65
66 static void
logfail(int exitcode,const char * fmt,...)67 logfail(int exitcode, const char *fmt, ...)
68 {
69 int oerrno = errno;
70 va_list ap;
71 char outs[1024];
72
73 outs[0] = 0;
74 if (fmt != NULL) {
75 va_start(ap, fmt);
76 vsnprintf(outs, sizeof(outs), fmt, ap);
77 va_end(ap);
78 }
79
80 errno = oerrno;
81 if (*outs != 0)
82 syslog(LOG_ERR, errno ? "%s: %m" : "%s", outs);
83 else
84 syslog(LOG_ERR, errno ? "%m" : "unknown error");
85
86 exit(exitcode);
87 }
88
89 /*
90 * Create a mbox in /var/mail for a given user, or make sure
91 * the permissions are correct for dma.
92 */
93
94 int
main(int argc,char ** argv)95 main(int argc, char **argv)
96 {
97 #if USE_CAPSICUM
98 cap_rights_t rights;
99 #endif
100 const char *user;
101 struct passwd *pw;
102 struct group *gr;
103 uid_t user_uid;
104 gid_t mail_gid;
105 int f, maildirfd;
106
107 /*
108 * Open log fd now for capability sandbox.
109 */
110 openlog("dma-mbox-create", LOG_NDELAY, LOG_MAIL);
111
112 errno = 0;
113 gr = getgrnam(DMA_GROUP);
114 if (!gr)
115 logfail(EX_CONFIG, "cannot find dma group `%s'", DMA_GROUP);
116
117 mail_gid = gr->gr_gid;
118
119 if (setgid(mail_gid) != 0)
120 logfail(EX_NOPERM, "cannot set gid to %d (%s)", mail_gid, DMA_GROUP);
121 if (getegid() != mail_gid)
122 logfail(EX_NOPERM, "cannot set gid to %d (%s), still at %d", mail_gid, DMA_GROUP, getegid());
123
124 /*
125 * We take exactly one argument: the username.
126 */
127 if (argc != 2) {
128 errno = 0;
129 logfail(EX_USAGE, "no arguments");
130 }
131 user = argv[1];
132
133 syslog(LOG_NOTICE, "creating mbox for `%s'", user);
134
135 /* the username may not contain a pathname separator */
136 if (strchr(user, '/')) {
137 errno = 0;
138 logfail(EX_DATAERR, "path separator in username `%s'", user);
139 exit(1);
140 }
141
142 /* verify the user exists */
143 errno = 0;
144 pw = getpwnam(user);
145 if (!pw)
146 logfail(EX_NOUSER, "cannot find user `%s'", user);
147
148 maildirfd = open(_PATH_MAILDIR, O_RDONLY);
149 if (maildirfd < 0)
150 logfail(EX_NOINPUT, "cannot open maildir %s", _PATH_MAILDIR);
151
152 /*
153 * Cache NLS data, for strerror, for err(3), before entering capability
154 * mode.
155 */
156 caph_cache_catpages();
157
158 /*
159 * Cache local time before entering Capsicum capability sandbox.
160 */
161 caph_cache_tzdata();
162
163 #if USE_CAPSICUM
164 cap_rights_init(&rights, CAP_CREATE, CAP_FCHMOD, CAP_FCHOWN,
165 CAP_LOOKUP, CAP_READ);
166 if (cap_rights_limit(maildirfd, &rights) < 0 && errno != ENOSYS)
167 err(EX_OSERR, "can't limit maildirfd rights");
168
169 /* Enter Capsicum capability sandbox */
170 if (caph_enter() < 0)
171 err(EX_OSERR, "cap_enter");
172 #endif
173
174 user_uid = pw->pw_uid;
175
176 f = openat(maildirfd, user, O_RDONLY|O_CREAT|O_NOFOLLOW, 0600);
177 if (f < 0)
178 logfail(EX_NOINPUT, "cannot open mbox `%s'", user);
179
180 if (fchown(f, user_uid, mail_gid))
181 logfail(EX_OSERR, "cannot change owner of mbox `%s'", user);
182
183 if (fchmod(f, 0620))
184 logfail(EX_OSERR, "cannot change permissions of mbox `%s'",
185 user);
186
187 /* file should be present with the right owner and permissions */
188
189 syslog(LOG_NOTICE, "successfully created mbox for `%s'", user);
190
191 return (0);
192 }
193