1 677d90f7 2021-03-12 op /*
  2 677d90f7 2021-03-12 op  * Copyright (c) 2021 Omar Polo <op@omarpolo.com>
  3 7be09703 2024-02-12 op  * Copyright (c) 2022 Claudio Jeker <claudio@openbsd.org>
  4 677d90f7 2021-03-12 op  *
  5 677d90f7 2021-03-12 op  * Permission to use, copy, modify, and distribute this software for any
  6 677d90f7 2021-03-12 op  * purpose with or without fee is hereby granted, provided that the above
  7 677d90f7 2021-03-12 op  * copyright notice and this permission notice appear in all copies.
  8 677d90f7 2021-03-12 op  *
  9 677d90f7 2021-03-12 op  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 10 677d90f7 2021-03-12 op  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 11 677d90f7 2021-03-12 op  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 12 677d90f7 2021-03-12 op  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 13 677d90f7 2021-03-12 op  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 14 677d90f7 2021-03-12 op  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 15 677d90f7 2021-03-12 op  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 16 677d90f7 2021-03-12 op  */
 17 677d90f7 2021-03-12 op 
 18 a9d11f81 2021-10-08 op #include "compat.h"
 19 a9d11f81 2021-10-08 op 
 20 f63b8f73 2022-04-24 op #include <limits.h>
 21 f63b8f73 2022-04-24 op 
 22 4b877649 2021-10-07 op #include "fs.h"
 23 754622a2 2021-03-15 op #include "telescope.h"
 24 677d90f7 2021-03-12 op 
 25 677d90f7 2021-03-12 op #ifdef __OpenBSD__
 26 677d90f7 2021-03-12 op 
 27 fced318d 2021-10-08 op # include <errno.h>
 28 35e1f40a 2021-03-14 op # include <stdlib.h>
 29 35e1f40a 2021-03-14 op # include <string.h>
 30 2b1f38ab 2021-03-13 op # include <unistd.h>
 31 2b1f38ab 2021-03-13 op 
 32 677d90f7 2021-03-12 op void
 33 17c10c65 2021-07-12 op sandbox_net_process(void)
 34 677d90f7 2021-03-12 op {
 35 d35e18b3 2024-02-04 op 	if (pledge("stdio inet dns recvfd", NULL) == -1)
 36 677d90f7 2021-03-12 op 		err(1, "pledge");
 37 677d90f7 2021-03-12 op }
 38 677d90f7 2021-03-12 op 
 39 b1d4d01b 2021-03-14 op void
 40 b1d4d01b 2021-03-14 op sandbox_ui_process(void)
 41 b1d4d01b 2021-03-14 op {
 42 35e1f40a 2021-03-14 op 	char path[PATH_MAX];
 43 35e1f40a 2021-03-14 op 
 44 de2a69bb 2021-05-17 op 	if (unveil("/tmp", "rwc") == -1)
 45 e9cb759e 2021-10-08 op 		err(1, "unveil(/tmp)");
 46 35e1f40a 2021-03-14 op 
 47 35e1f40a 2021-03-14 op 	strlcpy(path, getenv("HOME"), sizeof(path));
 48 35e1f40a 2021-03-14 op 	strlcat(path, "/Downloads", sizeof(path));
 49 4380c692 2021-10-08 op 	if (unveil(path, "rwc") == -1 && errno != ENOENT)
 50 fd0beb53 2021-10-07 op 		err(1, "unveil(%s)", path);
 51 35e1f40a 2021-03-14 op 
 52 4b877649 2021-10-07 op 	if (unveil(config_path_base, "rwc") == -1)
 53 fd0beb53 2021-10-07 op 		err(1, "unveil(%s)", config_path_base);
 54 35e1f40a 2021-03-14 op 
 55 4b877649 2021-10-07 op 	if (unveil(data_path_base, "rwc") == -1)
 56 fd0beb53 2021-10-07 op 		err(1, "unveil(%s)", data_path_base);
 57 4b877649 2021-10-07 op 
 58 4b877649 2021-10-07 op 	if (unveil(cache_path_base, "rwc") == -1)
 59 fd0beb53 2021-10-07 op 		err(1, "unveil(%s)", cache_path_base);
 60 4b877649 2021-10-07 op 
 61 d35e18b3 2024-02-04 op 	if (pledge("stdio rpath wpath cpath unix sendfd tty", NULL) == -1)
 62 35e1f40a 2021-03-14 op 		err(1, "pledge");
 63 35e1f40a 2021-03-14 op }
 64 35e1f40a 2021-03-14 op 
 65 a9d11f81 2021-10-08 op #elif HAVE_LINUX_LANDLOCK_H
 66 a9d11f81 2021-10-08 op 
 67 a9d11f81 2021-10-08 op #include <linux/landlock.h>
 68 a9d11f81 2021-10-08 op 
 69 a9d11f81 2021-10-08 op #include <sys/prctl.h>
 70 a9d11f81 2021-10-08 op #include <sys/stat.h>
 71 a9d11f81 2021-10-08 op #include <sys/syscall.h>
 72 a9d11f81 2021-10-08 op 
 73 fced318d 2021-10-08 op #include <errno.h>
 74 a9d11f81 2021-10-08 op #include <fcntl.h>
 75 a9d11f81 2021-10-08 op #include <stdlib.h>
 76 a9d11f81 2021-10-08 op #include <string.h>
 77 a9d11f81 2021-10-08 op #include <unistd.h>
 78 a9d11f81 2021-10-08 op 
 79 a9d11f81 2021-10-08 op /*
 80 a9d11f81 2021-10-08 op  * What's the deal with landlock?  While distro with linux >= 5.13
 81 a9d11f81 2021-10-08 op  * have the struct declarations, libc wrappers are missing.  The
 82 a9d11f81 2021-10-08 op  * sample landlock code provided by the authors includes these "shims"
 83 a9d11f81 2021-10-08 op  * in their example for the landlock API until libc provides them.
 84 a9d11f81 2021-10-08 op  */
 85 a9d11f81 2021-10-08 op 
 86 a9d11f81 2021-10-08 op #ifndef landlock_create_ruleset
 87 a9d11f81 2021-10-08 op static inline int
 88 a9d11f81 2021-10-08 op landlock_create_ruleset(const struct landlock_ruleset_attr *attr, size_t size,
 89 a9d11f81 2021-10-08 op     __u32 flags)
 90 a9d11f81 2021-10-08 op {
 91 a9d11f81 2021-10-08 op 	return syscall(__NR_landlock_create_ruleset, attr, size, flags);
 92 a9d11f81 2021-10-08 op }
 93 a9d11f81 2021-10-08 op #endif
 94 a9d11f81 2021-10-08 op 
 95 a9d11f81 2021-10-08 op #ifndef landlock_add_rule
 96 a9d11f81 2021-10-08 op static inline int
 97 a9d11f81 2021-10-08 op landlock_add_rule(int ruleset_fd, enum landlock_rule_type type,
 98 a9d11f81 2021-10-08 op     const void *attr, __u32 flags)
 99 a9d11f81 2021-10-08 op {
100 a9d11f81 2021-10-08 op 	return syscall(__NR_landlock_add_rule, ruleset_fd, type, attr, flags);
101 a9d11f81 2021-10-08 op }
102 a9d11f81 2021-10-08 op #endif
103 a9d11f81 2021-10-08 op 
104 a9d11f81 2021-10-08 op #ifndef landlock_restrict_self
105 a9d11f81 2021-10-08 op static inline int
106 a9d11f81 2021-10-08 op landlock_restrict_self(int ruleset_fd, __u32 flags)
107 a9d11f81 2021-10-08 op {
108 a9d11f81 2021-10-08 op 	return syscall(__NR_landlock_restrict_self, ruleset_fd, flags);
109 a9d11f81 2021-10-08 op }
110 a9d11f81 2021-10-08 op #endif
111 a9d11f81 2021-10-08 op 
112 7be09703 2024-02-12 op /*
113 7be09703 2024-02-12 op  * Maybe we should ship with a full copy of the linux headers because
114 7be09703 2024-02-12 op  * you never know...
115 7be09703 2024-02-12 op  */
116 7be09703 2024-02-12 op 
117 7be09703 2024-02-12 op #ifndef LANDLOCK_ACCESS_FS_REFER
118 7be09703 2024-02-12 op #define LANDLOCK_ACCESS_FS_REFER	(1ULL << 13)
119 7be09703 2024-02-12 op #endif
120 7be09703 2024-02-12 op 
121 7be09703 2024-02-12 op #ifndef LANDLOCK_ACCESS_FS_TRUNCATE
122 7be09703 2024-02-12 op #define LANDLOCK_ACCESS_FS_TRUNCATE	(1ULL << 14)
123 7be09703 2024-02-12 op #endif
124 7be09703 2024-02-12 op 
125 7be09703 2024-02-12 op static int landlock_state;
126 7be09703 2024-02-12 op static int landlock_fd;
127 7be09703 2024-02-12 op 
128 7be09703 2024-02-12 op /*
129 7be09703 2024-02-12 op  * Initialize landlock, which is stupidly complicated.
130 7be09703 2024-02-12 op  */
131 a9d11f81 2021-10-08 op static int
132 7be09703 2024-02-12 op landlock_init(void)
133 a9d11f81 2021-10-08 op {
134 7be09703 2024-02-12 op 	struct landlock_ruleset_attr rattr = {
135 7be09703 2024-02-12 op 		/*
136 7be09703 2024-02-12 op 		 * List all capabilities currently defined by landlock.
137 7be09703 2024-02-12 op 		 * Failure in doing so will implicitly allow those actions
138 7be09703 2024-02-12 op 		 * (i.e. omitting READ_FILE will allow to read _any_ file.)
139 7be09703 2024-02-12 op 		 */
140 7be09703 2024-02-12 op 		.handled_access_fs =
141 7be09703 2024-02-12 op 		LANDLOCK_ACCESS_FS_EXECUTE |
142 7be09703 2024-02-12 op 		LANDLOCK_ACCESS_FS_READ_FILE |
143 7be09703 2024-02-12 op 		LANDLOCK_ACCESS_FS_READ_DIR |
144 7be09703 2024-02-12 op 		LANDLOCK_ACCESS_FS_WRITE_FILE |
145 7be09703 2024-02-12 op 		LANDLOCK_ACCESS_FS_REMOVE_DIR |
146 7be09703 2024-02-12 op 		LANDLOCK_ACCESS_FS_REMOVE_FILE |
147 7be09703 2024-02-12 op 		LANDLOCK_ACCESS_FS_MAKE_CHAR |
148 7be09703 2024-02-12 op 		LANDLOCK_ACCESS_FS_MAKE_DIR |
149 7be09703 2024-02-12 op 		LANDLOCK_ACCESS_FS_MAKE_REG |
150 7be09703 2024-02-12 op 		LANDLOCK_ACCESS_FS_MAKE_SOCK |
151 7be09703 2024-02-12 op 		LANDLOCK_ACCESS_FS_MAKE_FIFO |
152 7be09703 2024-02-12 op 		LANDLOCK_ACCESS_FS_MAKE_BLOCK |
153 7be09703 2024-02-12 op 		LANDLOCK_ACCESS_FS_MAKE_SYM |
154 7be09703 2024-02-12 op 		LANDLOCK_ACCESS_FS_REFER |
155 7be09703 2024-02-12 op 		LANDLOCK_ACCESS_FS_TRUNCATE,
156 a9d11f81 2021-10-08 op 	};
157 7be09703 2024-02-12 op 	int abi;
158 a9d11f81 2021-10-08 op 
159 7be09703 2024-02-12 op 	if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) == -1)
160 7be09703 2024-02-12 op 		return -1;
161 7be09703 2024-02-12 op 
162 7be09703 2024-02-12 op 	abi = landlock_create_ruleset(NULL, 0, LANDLOCK_CREATE_RULESET_VERSION);
163 7be09703 2024-02-12 op 	if (abi == -1)
164 7be09703 2024-02-12 op 		return -1;
165 7be09703 2024-02-12 op 	if (abi < 2)
166 7be09703 2024-02-12 op 		rattr.handled_access_fs &= ~LANDLOCK_ACCESS_FS_REFER;
167 7be09703 2024-02-12 op 	if (abi < 3)
168 7be09703 2024-02-12 op 		rattr.handled_access_fs &= ~LANDLOCK_ACCESS_FS_TRUNCATE;
169 7be09703 2024-02-12 op 
170 7be09703 2024-02-12 op 	landlock_state = 1;
171 7be09703 2024-02-12 op 	return landlock_create_ruleset(&rattr, sizeof(rattr), 0);
172 a9d11f81 2021-10-08 op }
173 a9d11f81 2021-10-08 op 
174 a9d11f81 2021-10-08 op static int
175 7be09703 2024-02-12 op landlock_lock(void)
176 a9d11f81 2021-10-08 op {
177 7be09703 2024-02-12 op 	int saved_errno;
178 a9d11f81 2021-10-08 op 
179 7be09703 2024-02-12 op 	if (landlock_restrict_self(landlock_fd, 0)) {
180 7be09703 2024-02-12 op 		saved_errno = errno;
181 7be09703 2024-02-12 op 		close(landlock_fd);
182 7be09703 2024-02-12 op 		errno = saved_errno;
183 7be09703 2024-02-12 op 		landlock_state = -1;
184 a9d11f81 2021-10-08 op 		return -1;
185 7be09703 2024-02-12 op 	}
186 a9d11f81 2021-10-08 op 
187 7be09703 2024-02-12 op 	landlock_state = 2;
188 7be09703 2024-02-12 op 	close(landlock_fd);
189 7be09703 2024-02-12 op 	return 0;
190 a9d11f81 2021-10-08 op }
191 a9d11f81 2021-10-08 op static int
192 7be09703 2024-02-12 op landlock_unveil(const char *path, const char *permissions)
193 a9d11f81 2021-10-08 op {
194 7be09703 2024-02-12 op 	struct landlock_path_beneath_attr lpba;
195 7be09703 2024-02-12 op 	int fd, saved_errno;
196 a9d11f81 2021-10-08 op 
197 7be09703 2024-02-12 op 	if (landlock_state == 0) {
198 7be09703 2024-02-12 op 		if ((landlock_fd = landlock_init()) == -1) {
199 7be09703 2024-02-12 op 			landlock_state = -1;
200 7be09703 2024-02-12 op 			/* this kernel doesn't have landlock built in */
201 7be09703 2024-02-12 op 			if (errno == ENOSYS || errno == EOPNOTSUPP)
202 7be09703 2024-02-12 op 				return 0;
203 7be09703 2024-02-12 op 			return -1;
204 7be09703 2024-02-12 op 		}
205 7be09703 2024-02-12 op 	}
206 a9d11f81 2021-10-08 op 
207 7be09703 2024-02-12 op 	/* no landlock available */
208 7be09703 2024-02-12 op 	if (landlock_state == -1)
209 7be09703 2024-02-12 op 		return 0;
210 a9d11f81 2021-10-08 op 
211 7be09703 2024-02-12 op 	if (path == NULL && permissions == NULL)
212 7be09703 2024-02-12 op 		return landlock_lock();
213 a9d11f81 2021-10-08 op 
214 7be09703 2024-02-12 op 	if (path == NULL || permissions == NULL || landlock_state != 1) {
215 7be09703 2024-02-12 op 		errno = EINVAL;
216 7be09703 2024-02-12 op 		return -1;
217 7be09703 2024-02-12 op 	}
218 a9d11f81 2021-10-08 op 
219 7be09703 2024-02-12 op 	if (!strcmp(permissions, "r")) {
220 7be09703 2024-02-12 op 		fd = open(path, O_PATH | O_CLOEXEC);
221 7be09703 2024-02-12 op 		if (fd == -1)
222 7be09703 2024-02-12 op 			return -1;
223 7be09703 2024-02-12 op 		lpba = (struct landlock_path_beneath_attr){
224 7be09703 2024-02-12 op 			.allowed_access =
225 7be09703 2024-02-12 op 			    LANDLOCK_ACCESS_FS_READ_FILE |
226 7be09703 2024-02-12 op 			    LANDLOCK_ACCESS_FS_READ_DIR,
227 7be09703 2024-02-12 op 			.parent_fd = fd,
228 7be09703 2024-02-12 op 		};
229 7be09703 2024-02-12 op 		if (landlock_add_rule(landlock_fd, LANDLOCK_RULE_PATH_BENEATH,
230 7be09703 2024-02-12 op 		    &lpba, 0) == -1) {
231 7be09703 2024-02-12 op 			saved_errno = errno;
232 7be09703 2024-02-12 op 			close(fd);
233 7be09703 2024-02-12 op 			errno = saved_errno;
234 7be09703 2024-02-12 op 			return -1;
235 7be09703 2024-02-12 op 		}
236 7be09703 2024-02-12 op 		close(fd);
237 7be09703 2024-02-12 op 	}
238 7be09703 2024-02-12 op 
239 7be09703 2024-02-12 op 	return 0;
240 a9d11f81 2021-10-08 op }
241 a9d11f81 2021-10-08 op 
242 a9d11f81 2021-10-08 op void
243 a9d11f81 2021-10-08 op sandbox_net_process(void)
244 a9d11f81 2021-10-08 op {
245 ed1d237e 2021-11-27 op 	/*
246 7be09703 2024-02-12 op 	 * We don't know what paths are required for the TLS stack and
247 7be09703 2024-02-12 op 	 * DNS, so allow accessing read-only the whole system.
248 ed1d237e 2021-11-27 op 	 * Yes, it sucks.
249 ed1d237e 2021-11-27 op 	 */
250 7be09703 2024-02-12 op 
251 7be09703 2024-02-12 op 	if (landlock_unveil("/", "r") == -1)
252 7be09703 2024-02-12 op 		err(1, "landlock_unveil(/, r)");
253 7be09703 2024-02-12 op 	if (landlock_unveil(NULL, NULL) == -1)
254 7be09703 2024-02-12 op 		err(1, "landlock_unveil(NULL, NULL)");
255 a9d11f81 2021-10-08 op }
256 a9d11f81 2021-10-08 op 
257 a9d11f81 2021-10-08 op void
258 a9d11f81 2021-10-08 op sandbox_ui_process(void)
259 a9d11f81 2021-10-08 op {
260 4ab3b651 2021-11-29 op 	/*
261 f63b8f73 2022-04-24 op 	 * Needs to be able to read files *and* execute programs,
262 f63b8f73 2022-04-24 op 	 * can't be sandboxed.
263 4ab3b651 2021-11-29 op 	 */
264 f63b8f73 2022-04-24 op 	return;
265 a9d11f81 2021-10-08 op }
266 a9d11f81 2021-10-08 op 
267 68a9b7d2 2021-03-13 op #else
268 68a9b7d2 2021-03-13 op 
269 68a9b7d2 2021-03-13 op void
270 17c10c65 2021-07-12 op sandbox_net_process(void)
271 68a9b7d2 2021-03-13 op {
272 68a9b7d2 2021-03-13 op 	return;
273 68a9b7d2 2021-03-13 op }
274 68a9b7d2 2021-03-13 op 
275 35e1f40a 2021-03-14 op void
276 35e1f40a 2021-03-14 op sandbox_ui_process(void)
277 35e1f40a 2021-03-14 op {
278 35e1f40a 2021-03-14 op 	return;
279 35e1f40a 2021-03-14 op }
280 35e1f40a 2021-03-14 op 
281 677d90f7 2021-03-12 op #endif