1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2010 The FreeBSD Foundation
5 * Copyright (c) 2011 Pawel Jakub Dawidek <pawel@dawidek.net>
6 * All rights reserved.
7 *
8 * This software was developed by Pawel Jakub Dawidek under sponsorship from
9 * the FreeBSD Foundation.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 * notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in the
18 * documentation and/or other materials provided with the distribution.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33 #include <sys/param.h>
34 #include <sys/disk.h>
35 #include <sys/ioctl.h>
36 #include <sys/jail.h>
37 #include <sys/stat.h>
38 #ifdef HAVE_CAPSICUM
39 #include <sys/capsicum.h>
40 #include <geom/gate/g_gate.h>
41 #endif
42
43 #include <errno.h>
44 #include <fcntl.h>
45 #include <pwd.h>
46 #include <stdarg.h>
47 #include <stdbool.h>
48 #include <stdio.h>
49 #include <string.h>
50 #include <unistd.h>
51
52 #include <pjdlog.h>
53
54 #include "hast.h"
55 #include "subr.h"
56
57 int
vsnprlcat(char * str,size_t size,const char * fmt,va_list ap)58 vsnprlcat(char *str, size_t size, const char *fmt, va_list ap)
59 {
60 size_t len;
61
62 len = strlen(str);
63 return (vsnprintf(str + len, size - len, fmt, ap));
64 }
65
66 int
snprlcat(char * str,size_t size,const char * fmt,...)67 snprlcat(char *str, size_t size, const char *fmt, ...)
68 {
69 va_list ap;
70 int result;
71
72 va_start(ap, fmt);
73 result = vsnprlcat(str, size, fmt, ap);
74 va_end(ap);
75 return (result);
76 }
77
78 int
provinfo(struct hast_resource * res,bool dowrite)79 provinfo(struct hast_resource *res, bool dowrite)
80 {
81 struct stat sb;
82
83 PJDLOG_ASSERT(res->hr_localpath != NULL &&
84 res->hr_localpath[0] != '\0');
85
86 if (res->hr_localfd == -1) {
87 res->hr_localfd = open(res->hr_localpath,
88 dowrite ? O_RDWR : O_RDONLY);
89 if (res->hr_localfd == -1) {
90 pjdlog_errno(LOG_ERR, "Unable to open %s",
91 res->hr_localpath);
92 return (-1);
93 }
94 }
95 if (fstat(res->hr_localfd, &sb) == -1) {
96 pjdlog_errno(LOG_ERR, "Unable to stat %s", res->hr_localpath);
97 return (-1);
98 }
99 if (S_ISCHR(sb.st_mode)) {
100 /*
101 * If this is character device, it is most likely GEOM provider.
102 */
103 if (ioctl(res->hr_localfd, DIOCGMEDIASIZE,
104 &res->hr_local_mediasize) == -1) {
105 pjdlog_errno(LOG_ERR,
106 "Unable obtain provider %s mediasize",
107 res->hr_localpath);
108 return (-1);
109 }
110 if (ioctl(res->hr_localfd, DIOCGSECTORSIZE,
111 &res->hr_local_sectorsize) == -1) {
112 pjdlog_errno(LOG_ERR,
113 "Unable obtain provider %s sectorsize",
114 res->hr_localpath);
115 return (-1);
116 }
117 } else if (S_ISREG(sb.st_mode)) {
118 /*
119 * We also support regular files for which we hardcode
120 * sector size of 512 bytes.
121 */
122 res->hr_local_mediasize = sb.st_size;
123 res->hr_local_sectorsize = 512;
124 } else {
125 /*
126 * We support no other file types.
127 */
128 pjdlog_error("%s is neither GEOM provider nor regular file.",
129 res->hr_localpath);
130 errno = EFTYPE;
131 return (-1);
132 }
133 return (0);
134 }
135
136 const char *
role2str(int role)137 role2str(int role)
138 {
139
140 switch (role) {
141 case HAST_ROLE_INIT:
142 return ("init");
143 case HAST_ROLE_PRIMARY:
144 return ("primary");
145 case HAST_ROLE_SECONDARY:
146 return ("secondary");
147 }
148 return ("unknown");
149 }
150
151 int
drop_privs(const struct hast_resource * res)152 drop_privs(const struct hast_resource *res)
153 {
154 char jailhost[sizeof(res->hr_name) * 2];
155 struct jail jailst;
156 struct passwd *pw;
157 uid_t ruid, euid, suid;
158 gid_t rgid, egid, sgid;
159 gid_t gidset[1];
160 bool capsicum, jailed;
161
162 /*
163 * According to getpwnam(3) we have to clear errno before calling the
164 * function to be able to distinguish between an error and missing
165 * entry (with is not treated as error by getpwnam(3)).
166 */
167 errno = 0;
168 pw = getpwnam(HAST_USER);
169 if (pw == NULL) {
170 if (errno != 0) {
171 pjdlog_errno(LOG_ERR,
172 "Unable to find info about '%s' user", HAST_USER);
173 return (-1);
174 } else {
175 pjdlog_error("'%s' user doesn't exist.", HAST_USER);
176 errno = ENOENT;
177 return (-1);
178 }
179 }
180
181 bzero(&jailst, sizeof(jailst));
182 jailst.version = JAIL_API_VERSION;
183 jailst.path = pw->pw_dir;
184 if (res == NULL) {
185 (void)snprintf(jailhost, sizeof(jailhost), "hastctl");
186 } else {
187 (void)snprintf(jailhost, sizeof(jailhost), "hastd: %s (%s)",
188 res->hr_name, role2str(res->hr_role));
189 }
190 jailst.hostname = jailhost;
191 jailst.jailname = NULL;
192 jailst.ip4s = 0;
193 jailst.ip4 = NULL;
194 jailst.ip6s = 0;
195 jailst.ip6 = NULL;
196 if (jail(&jailst) >= 0) {
197 jailed = true;
198 } else {
199 jailed = false;
200 pjdlog_errno(LOG_WARNING,
201 "Unable to jail to directory to %s", pw->pw_dir);
202 if (chroot(pw->pw_dir) == -1) {
203 pjdlog_errno(LOG_ERR,
204 "Unable to change root directory to %s",
205 pw->pw_dir);
206 return (-1);
207 }
208 }
209 PJDLOG_VERIFY(chdir("/") == 0);
210 gidset[0] = pw->pw_gid;
211 if (setgroups(1, gidset) == -1) {
212 pjdlog_errno(LOG_ERR, "Unable to set groups to gid %u",
213 (unsigned int)pw->pw_gid);
214 return (-1);
215 }
216 if (setgid(pw->pw_gid) == -1) {
217 pjdlog_errno(LOG_ERR, "Unable to set gid to %u",
218 (unsigned int)pw->pw_gid);
219 return (-1);
220 }
221 if (setuid(pw->pw_uid) == -1) {
222 pjdlog_errno(LOG_ERR, "Unable to set uid to %u",
223 (unsigned int)pw->pw_uid);
224 return (-1);
225 }
226
227 #ifdef HAVE_CAPSICUM
228 capsicum = (cap_enter() == 0);
229 if (!capsicum) {
230 pjdlog_common(LOG_DEBUG, 1, errno,
231 "Unable to sandbox using capsicum");
232 } else if (res != NULL) {
233 cap_rights_t rights;
234 static const unsigned long geomcmds[] = {
235 DIOCGDELETE,
236 DIOCGFLUSH
237 };
238
239 PJDLOG_ASSERT(res->hr_role == HAST_ROLE_PRIMARY ||
240 res->hr_role == HAST_ROLE_SECONDARY);
241
242 cap_rights_init(&rights, CAP_FLOCK, CAP_IOCTL, CAP_PREAD,
243 CAP_PWRITE);
244 if (cap_rights_limit(res->hr_localfd, &rights) == -1) {
245 pjdlog_errno(LOG_ERR,
246 "Unable to limit capability rights on local descriptor");
247 }
248 if (cap_ioctls_limit(res->hr_localfd, geomcmds,
249 nitems(geomcmds)) == -1) {
250 pjdlog_errno(LOG_ERR,
251 "Unable to limit allowed GEOM ioctls");
252 }
253
254 if (res->hr_role == HAST_ROLE_PRIMARY) {
255 static const unsigned long ggatecmds[] = {
256 G_GATE_CMD_MODIFY,
257 G_GATE_CMD_START,
258 G_GATE_CMD_DONE,
259 G_GATE_CMD_DESTROY
260 };
261
262 cap_rights_init(&rights, CAP_IOCTL);
263 if (cap_rights_limit(res->hr_ggatefd, &rights) == -1) {
264 pjdlog_errno(LOG_ERR,
265 "Unable to limit capability rights to CAP_IOCTL on ggate descriptor");
266 }
267 if (cap_ioctls_limit(res->hr_ggatefd, ggatecmds,
268 nitems(ggatecmds)) == -1) {
269 pjdlog_errno(LOG_ERR,
270 "Unable to limit allowed ggate ioctls");
271 }
272 }
273 }
274 #else
275 capsicum = false;
276 #endif
277
278 /*
279 * Better be sure that everything succeeded.
280 */
281 PJDLOG_VERIFY(getresuid(&ruid, &euid, &suid) == 0);
282 PJDLOG_VERIFY(ruid == pw->pw_uid);
283 PJDLOG_VERIFY(euid == pw->pw_uid);
284 PJDLOG_VERIFY(suid == pw->pw_uid);
285 PJDLOG_VERIFY(getresgid(&rgid, &egid, &sgid) == 0);
286 PJDLOG_VERIFY(rgid == pw->pw_gid);
287 PJDLOG_VERIFY(egid == pw->pw_gid);
288 PJDLOG_VERIFY(sgid == pw->pw_gid);
289 PJDLOG_VERIFY(getgroups(0, NULL) == 1);
290 PJDLOG_VERIFY(getgroups(1, gidset) == 1);
291 PJDLOG_VERIFY(gidset[0] == pw->pw_gid);
292
293 pjdlog_debug(1,
294 "Privileges successfully dropped using %s%s+setgid+setuid.",
295 capsicum ? "capsicum+" : "", jailed ? "jail" : "chroot");
296
297 return (0);
298 }
299