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Date:: Sun Feb 6 20:15:21 2022 UTC
Message:: portable: add support for landlock landlock is a new set of linux APIs that is conceptually similar to unveil(2): the idea is to restrict what a process can do on a specified part of the filesystem. There are some differences in the behaviour: the major one being that the landlock ruleset is inherited across execve(2). This just restricts the libexec helpers by completely revoking ANY filesystem access; after all they are the biggest attack surface. got send/fetch/clone *may* end up spawning ssh(1), so at the moment is not possible to landlock the main process. From Omar Polo.
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  1 ad242220 2018-09-08 stsp /*
  2 5d56da81 2019-01-13 stsp  * Copyright (c) 2018, 2019 Stefan Sperling <stsp@openbsd.org>
  3 ad242220 2018-09-08 stsp  *
  4 ad242220 2018-09-08 stsp  * Permission to use, copy, modify, and distribute this software for any
  5 ad242220 2018-09-08 stsp  * purpose with or without fee is hereby granted, provided that the above
  6 ad242220 2018-09-08 stsp  * copyright notice and this permission notice appear in all copies.
  7 ad242220 2018-09-08 stsp  *
  8 ad242220 2018-09-08 stsp  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  9 ad242220 2018-09-08 stsp  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 10 ad242220 2018-09-08 stsp  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 11 ad242220 2018-09-08 stsp  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 12 ad242220 2018-09-08 stsp  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 13 ad242220 2018-09-08 stsp  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 14 ad242220 2018-09-08 stsp  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 15 ad242220 2018-09-08 stsp  */
 16 ad242220 2018-09-08 stsp 
 17 ad242220 2018-09-08 stsp #include <sys/types.h>
 18 ad242220 2018-09-08 stsp #include <sys/uio.h>
 19 ad242220 2018-09-08 stsp #include <sys/time.h>
 20 ad242220 2018-09-08 stsp 
 21 ad242220 2018-09-08 stsp #include <stdint.h>
 22 12ce7a6c 2019-08-12 stsp #include <limits.h>
 23 99437157 2018-11-11 stsp #include <signal.h>
 24 ad242220 2018-09-08 stsp #include <stdio.h>
 25 ad242220 2018-09-08 stsp #include <stdlib.h>
 26 ad242220 2018-09-08 stsp #include <string.h>
 27 81a12da5 2020-09-09 naddy #include <unistd.h>
 28 ad242220 2018-09-08 stsp #include <zlib.h>
 29 ad242220 2018-09-08 stsp 
 30 dd038bc6 2021-09-21 thomas.ad #include "got_compat.h"
 31 dd038bc6 2021-09-21 thomas.ad 
 32 ad242220 2018-09-08 stsp #include "got_error.h"
 33 ad242220 2018-09-08 stsp #include "got_object.h"
 34 ad242220 2018-09-08 stsp 
 35 ad242220 2018-09-08 stsp #include "got_lib_delta.h"
 36 ad242220 2018-09-08 stsp #include "got_lib_inflate.h"
 37 ad242220 2018-09-08 stsp #include "got_lib_object.h"
 38 ad242220 2018-09-08 stsp #include "got_lib_object_parse.h"
 39 ad242220 2018-09-08 stsp #include "got_lib_privsep.h"
 40 d5c81d44 2021-07-08 stsp #include "got_lib_sha1.h"
 41 ad242220 2018-09-08 stsp 
 42 99437157 2018-11-11 stsp static volatile sig_atomic_t sigint_received;
 43 99437157 2018-11-11 stsp 
 44 99437157 2018-11-11 stsp static void
 45 99437157 2018-11-11 stsp catch_sigint(int signo)
 46 99437157 2018-11-11 stsp {
 47 99437157 2018-11-11 stsp 	sigint_received = 1;
 48 99437157 2018-11-11 stsp }
 49 99437157 2018-11-11 stsp 
 50 ad242220 2018-09-08 stsp int
 51 ad242220 2018-09-08 stsp main(int argc, char *argv[])
 52 ad242220 2018-09-08 stsp {
 53 ad242220 2018-09-08 stsp 	const struct got_error *err = NULL;
 54 ad242220 2018-09-08 stsp 	struct imsgbuf ibuf;
 55 ad242220 2018-09-08 stsp 	size_t datalen;
 56 ad242220 2018-09-08 stsp 
 57 99437157 2018-11-11 stsp 	signal(SIGINT, catch_sigint);
 58 99437157 2018-11-11 stsp 
 59 ad242220 2018-09-08 stsp 	imsg_init(&ibuf, GOT_IMSG_FD_CHILD);
 60 ad242220 2018-09-08 stsp 
 61 2ff12563 2018-09-15 stsp #ifndef PROFILE
 62 ad242220 2018-09-08 stsp 	/* revoke access to most system calls */
 63 ad242220 2018-09-08 stsp 	if (pledge("stdio recvfd", NULL) == -1) {
 64 638f9024 2019-05-13 stsp 		err = got_error_from_errno("pledge");
 65 ad242220 2018-09-08 stsp 		got_privsep_send_error(&ibuf, err);
 66 ad242220 2018-09-08 stsp 		return 1;
 67 ad242220 2018-09-08 stsp 	}
 68 97799ccd 2022-02-06 thomas 
 69 97799ccd 2022-02-06 thomas 	/* revoke fs access */
 70 97799ccd 2022-02-06 thomas 	if (landlock_no_fs() == -1) {
 71 97799ccd 2022-02-06 thomas 		err = got_error_from_errno("landlock_no_fs");
 72 97799ccd 2022-02-06 thomas 		got_privsep_send_error(&ibuf, err);
 73 97799ccd 2022-02-06 thomas 		return 1;
 74 97799ccd 2022-02-06 thomas 	}
 75 2ff12563 2018-09-15 stsp #endif
 76 ad242220 2018-09-08 stsp 
 77 656b1f76 2019-05-11 jcs 	for (;;) {
 78 ad242220 2018-09-08 stsp 		struct imsg imsg, imsg_outfd;
 79 ad242220 2018-09-08 stsp 		FILE *f = NULL;
 80 ad242220 2018-09-08 stsp 		size_t size;
 81 ebc55e2d 2018-12-24 stsp 		struct got_object *obj = NULL;
 82 ac544f8c 2019-01-13 stsp 		uint8_t *buf = NULL;
 83 d5c81d44 2021-07-08 stsp 		struct got_object_id id;
 84 d5c81d44 2021-07-08 stsp 		struct got_object_id expected_id;
 85 d5c81d44 2021-07-08 stsp 		struct got_inflate_checksum csum;
 86 d5c81d44 2021-07-08 stsp 		SHA1_CTX sha1_ctx;
 87 656b1f76 2019-05-11 jcs 
 88 d5c81d44 2021-07-08 stsp 		SHA1Init(&sha1_ctx);
 89 d5c81d44 2021-07-08 stsp 		memset(&csum, 0, sizeof(csum));
 90 d5c81d44 2021-07-08 stsp 		csum.output_sha1 = &sha1_ctx;
 91 d5c81d44 2021-07-08 stsp 
 92 55da3778 2018-09-10 stsp 		memset(&imsg, 0, sizeof(imsg));
 93 ad242220 2018-09-08 stsp 		imsg.fd = -1;
 94 55da3778 2018-09-10 stsp 		memset(&imsg_outfd, 0, sizeof(imsg_outfd));
 95 ad242220 2018-09-08 stsp 		imsg_outfd.fd = -1;
 96 ad242220 2018-09-08 stsp 
 97 99437157 2018-11-11 stsp 		if (sigint_received) {
 98 99437157 2018-11-11 stsp 			err = got_error(GOT_ERR_CANCELLED);
 99 99437157 2018-11-11 stsp 			break;
100 99437157 2018-11-11 stsp 		}
101 99437157 2018-11-11 stsp 
102 ad242220 2018-09-08 stsp 		err = got_privsep_recv_imsg(&imsg, &ibuf, 0);
103 ad242220 2018-09-08 stsp 		if (err) {
104 876c234b 2018-09-10 stsp 			if (err->code == GOT_ERR_PRIVSEP_PIPE)
105 ad242220 2018-09-08 stsp 				err = NULL;
106 ad242220 2018-09-08 stsp 			break;
107 ad242220 2018-09-08 stsp 		}
108 ad242220 2018-09-08 stsp 
109 ad242220 2018-09-08 stsp 		if (imsg.hdr.type == GOT_IMSG_STOP)
110 ad242220 2018-09-08 stsp 			break;
111 ad242220 2018-09-08 stsp 
112 ad242220 2018-09-08 stsp 		if (imsg.hdr.type != GOT_IMSG_BLOB_REQUEST) {
113 ad242220 2018-09-08 stsp 			err = got_error(GOT_ERR_PRIVSEP_MSG);
114 ad242220 2018-09-08 stsp 			goto done;
115 ad242220 2018-09-08 stsp 		}
116 ad242220 2018-09-08 stsp 
117 d5c81d44 2021-07-08 stsp 		datalen = imsg.hdr.len - IMSG_HEADER_SIZE;
118 d5c81d44 2021-07-08 stsp 		if (datalen != sizeof(expected_id)) {
119 d5c81d44 2021-07-08 stsp 			err = got_error(GOT_ERR_PRIVSEP_LEN);
120 d5c81d44 2021-07-08 stsp 			goto done;
121 d5c81d44 2021-07-08 stsp 		}
122 d5c81d44 2021-07-08 stsp 		memcpy(&expected_id, imsg.data, sizeof(expected_id));
123 d5c81d44 2021-07-08 stsp 
124 ad242220 2018-09-08 stsp 		if (imsg.fd == -1) {
125 ad242220 2018-09-08 stsp 			err = got_error(GOT_ERR_PRIVSEP_NO_FD);
126 ad242220 2018-09-08 stsp 			goto done;
127 ad242220 2018-09-08 stsp 		}
128 ad242220 2018-09-08 stsp 
129 ad242220 2018-09-08 stsp 		err = got_privsep_recv_imsg(&imsg_outfd, &ibuf, 0);
130 ad242220 2018-09-08 stsp 		if (err) {
131 ad242220 2018-09-08 stsp 			if (imsg.hdr.len == 0)
132 ad242220 2018-09-08 stsp 				err = NULL;
133 ad242220 2018-09-08 stsp 			break;
134 ad242220 2018-09-08 stsp 		}
135 ad242220 2018-09-08 stsp 
136 ad242220 2018-09-08 stsp 		if (imsg_outfd.hdr.type == GOT_IMSG_STOP)
137 ad242220 2018-09-08 stsp 			break;
138 ad242220 2018-09-08 stsp 
139 ad242220 2018-09-08 stsp 		if (imsg_outfd.hdr.type != GOT_IMSG_BLOB_OUTFD) {
140 ad242220 2018-09-08 stsp 			err = got_error(GOT_ERR_PRIVSEP_MSG);
141 ad242220 2018-09-08 stsp 			goto done;
142 ad242220 2018-09-08 stsp 		}
143 ad242220 2018-09-08 stsp 
144 ad242220 2018-09-08 stsp 		datalen = imsg_outfd.hdr.len - IMSG_HEADER_SIZE;
145 ad242220 2018-09-08 stsp 		if (datalen != 0) {
146 ad242220 2018-09-08 stsp 			err = got_error(GOT_ERR_PRIVSEP_LEN);
147 ad242220 2018-09-08 stsp 			goto done;
148 ad242220 2018-09-08 stsp 		}
149 ad242220 2018-09-08 stsp 		if (imsg_outfd.fd == -1) {
150 ad242220 2018-09-08 stsp 			err = got_error(GOT_ERR_PRIVSEP_NO_FD);
151 ad242220 2018-09-08 stsp 			goto done;
152 ad242220 2018-09-08 stsp 		}
153 ad242220 2018-09-08 stsp 
154 ebc55e2d 2018-12-24 stsp 		err = got_object_read_header(&obj, imsg.fd);
155 ebc55e2d 2018-12-24 stsp 		if (err)
156 ebc55e2d 2018-12-24 stsp 			goto done;
157 ebc55e2d 2018-12-24 stsp 
158 ebc55e2d 2018-12-24 stsp 		if (lseek(imsg.fd, SEEK_SET, 0) == -1) {
159 638f9024 2019-05-13 stsp 			err = got_error_from_errno("lseek");
160 ebc55e2d 2018-12-24 stsp 			goto done;
161 ebc55e2d 2018-12-24 stsp 		}
162 ebc55e2d 2018-12-24 stsp 
163 ad242220 2018-09-08 stsp 		f = fdopen(imsg.fd, "rb");
164 ad242220 2018-09-08 stsp 		if (f == NULL) {
165 638f9024 2019-05-13 stsp 			err = got_error_from_errno("fdopen");
166 ad242220 2018-09-08 stsp 			goto done;
167 ad242220 2018-09-08 stsp 		}
168 ad242220 2018-09-08 stsp 
169 cc626439 2019-07-15 stsp 		if (obj->size + obj->hdrlen <=
170 cc626439 2019-07-15 stsp 		    GOT_PRIVSEP_INLINE_BLOB_DATA_MAX) {
171 d5c81d44 2021-07-08 stsp 			err = got_inflate_to_mem(&buf, &size, NULL, &csum, f);
172 ac544f8c 2019-01-13 stsp 			if (err)
173 ac544f8c 2019-01-13 stsp 				goto done;
174 ac544f8c 2019-01-13 stsp 		} else {
175 d5c81d44 2021-07-08 stsp 			err = got_inflate_to_fd(&size, f, &csum, imsg_outfd.fd);
176 ac544f8c 2019-01-13 stsp 			if (err)
177 ac544f8c 2019-01-13 stsp 				goto done;
178 ac544f8c 2019-01-13 stsp 		}
179 d5c81d44 2021-07-08 stsp 		SHA1Final(id.sha1, &sha1_ctx);
180 d5c81d44 2021-07-08 stsp 		if (memcmp(expected_id.sha1, id.sha1, SHA1_DIGEST_LENGTH) != 0) {
181 d5c81d44 2021-07-08 stsp 			char buf[SHA1_DIGEST_STRING_LENGTH];
182 d5c81d44 2021-07-08 stsp 			err = got_error_fmt(GOT_ERR_OBJ_CSUM,
183 d5c81d44 2021-07-08 stsp 			    "checksum failure for object %s",
184 d5c81d44 2021-07-08 stsp 			    got_sha1_digest_to_str(expected_id.sha1, buf,
185 d5c81d44 2021-07-08 stsp 			    sizeof(buf)));
186 d5c81d44 2021-07-08 stsp 			goto done;
187 d5c81d44 2021-07-08 stsp 		}
188 ad242220 2018-09-08 stsp 
189 f392e333 2018-12-24 stsp 		if (size < obj->hdrlen) {
190 f392e333 2018-12-24 stsp 			err = got_error(GOT_ERR_BAD_OBJ_HDR);
191 f392e333 2018-12-24 stsp 			goto done;
192 f392e333 2018-12-24 stsp 		}
193 f392e333 2018-12-24 stsp 
194 ac544f8c 2019-01-13 stsp 		err = got_privsep_send_blob(&ibuf, size, obj->hdrlen, buf);
195 ad242220 2018-09-08 stsp done:
196 4492af84 2019-07-15 stsp 		free(buf);
197 fb43ecf1 2019-02-11 stsp 		if (f) {
198 56b63ca4 2021-01-22 stsp 			if (fclose(f) == EOF && err == NULL)
199 638f9024 2019-05-13 stsp 				err = got_error_from_errno("fclose");
200 3a6ce05a 2019-02-11 stsp 		} else if (imsg.fd != -1) {
201 08578a35 2021-01-22 stsp 			if (close(imsg.fd) == -1 && err == NULL)
202 638f9024 2019-05-13 stsp 				err = got_error_from_errno("close");
203 3a6ce05a 2019-02-11 stsp 		}
204 3a6ce05a 2019-02-11 stsp 		if (imsg_outfd.fd != -1) {
205 08578a35 2021-01-22 stsp 			if (close(imsg_outfd.fd) == -1 && err == NULL)
206 638f9024 2019-05-13 stsp 				err = got_error_from_errno("close");
207 3a6ce05a 2019-02-11 stsp 		}
208 3a6ce05a 2019-02-11 stsp 
209 ad242220 2018-09-08 stsp 		imsg_free(&imsg);
210 ad242220 2018-09-08 stsp 		imsg_free(&imsg_outfd);
211 ebc55e2d 2018-12-24 stsp 		if (obj)
212 ebc55e2d 2018-12-24 stsp 			got_object_close(obj);
213 99437157 2018-11-11 stsp 		if (err)
214 ad242220 2018-09-08 stsp 			break;
215 ad242220 2018-09-08 stsp 	}
216 ad242220 2018-09-08 stsp 
217 ad242220 2018-09-08 stsp 	imsg_clear(&ibuf);
218 99437157 2018-11-11 stsp 	if (err) {
219 80d5f134 2018-11-11 stsp 		if (!sigint_received && err->code != GOT_ERR_PRIVSEP_PIPE) {
220 80d5f134 2018-11-11 stsp 			fprintf(stderr, "%s: %s\n", getprogname(), err->msg);
221 99437157 2018-11-11 stsp 			got_privsep_send_error(&ibuf, err);
222 80d5f134 2018-11-11 stsp 		}
223 99437157 2018-11-11 stsp 	}
224 08578a35 2021-01-22 stsp 	if (close(GOT_IMSG_FD_CHILD) == -1 && err == NULL)
225 638f9024 2019-05-13 stsp 		err = got_error_from_errno("close");
226 ad242220 2018-09-08 stsp 	return err ? 1 : 0;
227 ad242220 2018-09-08 stsp }