1 /*
2  * Copyright (c) 2018, 2019 Stefan Sperling <stsp@openbsd.org>
3  *
4  * Permission to use, copy, modify, and distribute this software for any
5  * purpose with or without fee is hereby granted, provided that the above
6  * copyright notice and this permission notice appear in all copies.
7  *
8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15  */
16 
17 #include <sys/types.h>
18 #include <sys/uio.h>
19 #include <sys/time.h>
20 
21 #include <stdint.h>
22 #include <limits.h>
23 #include <signal.h>
24 #include <stdio.h>
25 #include <stdlib.h>
26 #include <string.h>
27 #include <unistd.h>
28 #include <zlib.h>
29 
30 #include "got_compat.h"
31 
32 #include "got_error.h"
33 #include "got_object.h"
34 
35 #include "got_lib_delta.h"
36 #include "got_lib_inflate.h"
37 #include "got_lib_object.h"
38 #include "got_lib_object_parse.h"
39 #include "got_lib_privsep.h"
40 #include "got_lib_sha1.h"
41 
42 static volatile sig_atomic_t sigint_received;
43 
44 static void
45 catch_sigint(int signo)
46 {
47 	sigint_received = 1;
48 }
49 
50 int
51 main(int argc, char *argv[])
52 {
53 	const struct got_error *err = NULL;
54 	struct imsgbuf ibuf;
55 	size_t datalen;
56 
57 	signal(SIGINT, catch_sigint);
58 
59 	imsg_init(&ibuf, GOT_IMSG_FD_CHILD);
60 
61 #ifndef PROFILE
62 	/* revoke access to most system calls */
63 	if (pledge("stdio recvfd", NULL) == -1) {
64 		err = got_error_from_errno("pledge");
65 		got_privsep_send_error(&ibuf, err);
66 		return 1;
67 	}
68 
69 	/* revoke fs access */
70 	if (landlock_no_fs() == -1) {
71 		err = got_error_from_errno("landlock_no_fs");
72 		got_privsep_send_error(&ibuf, err);
73 		return 1;
74 	}
75 	if (cap_enter() == -1) {
76 		err = got_error_from_errno("cap_enter");
77 		got_privsep_send_error(&ibuf, err);
78 		return 1;
79 	}
80 #endif
81 
82 	for (;;) {
83 		struct imsg imsg, imsg_outfd;
84 		FILE *f = NULL;
85 		size_t size;
86 		struct got_object *obj = NULL;
87 		uint8_t *buf = NULL;
88 		struct got_object_id id;
89 		struct got_object_id expected_id;
90 		struct got_inflate_checksum csum;
91 		SHA1_CTX sha1_ctx;
92 
93 		SHA1Init(&sha1_ctx);
94 		memset(&csum, 0, sizeof(csum));
95 		csum.output_sha1 = &sha1_ctx;
96 
97 		memset(&imsg, 0, sizeof(imsg));
98 		imsg.fd = -1;
99 		memset(&imsg_outfd, 0, sizeof(imsg_outfd));
100 		imsg_outfd.fd = -1;
101 
102 		if (sigint_received) {
103 			err = got_error(GOT_ERR_CANCELLED);
104 			break;
105 		}
106 
107 		err = got_privsep_recv_imsg(&imsg, &ibuf, 0);
108 		if (err) {
109 			if (err->code == GOT_ERR_PRIVSEP_PIPE)
110 				err = NULL;
111 			break;
112 		}
113 
114 		if (imsg.hdr.type == GOT_IMSG_STOP)
115 			break;
116 
117 		if (imsg.hdr.type != GOT_IMSG_BLOB_REQUEST) {
118 			err = got_error(GOT_ERR_PRIVSEP_MSG);
119 			goto done;
120 		}
121 
122 		datalen = imsg.hdr.len - IMSG_HEADER_SIZE;
123 		if (datalen != sizeof(expected_id)) {
124 			err = got_error(GOT_ERR_PRIVSEP_LEN);
125 			goto done;
126 		}
127 		memcpy(&expected_id, imsg.data, sizeof(expected_id));
128 
129 		if (imsg.fd == -1) {
130 			err = got_error(GOT_ERR_PRIVSEP_NO_FD);
131 			goto done;
132 		}
133 
134 		err = got_privsep_recv_imsg(&imsg_outfd, &ibuf, 0);
135 		if (err) {
136 			if (imsg.hdr.len == 0)
137 				err = NULL;
138 			break;
139 		}
140 
141 		if (imsg_outfd.hdr.type == GOT_IMSG_STOP)
142 			break;
143 
144 		if (imsg_outfd.hdr.type != GOT_IMSG_BLOB_OUTFD) {
145 			err = got_error(GOT_ERR_PRIVSEP_MSG);
146 			goto done;
147 		}
148 
149 		datalen = imsg_outfd.hdr.len - IMSG_HEADER_SIZE;
150 		if (datalen != 0) {
151 			err = got_error(GOT_ERR_PRIVSEP_LEN);
152 			goto done;
153 		}
154 		if (imsg_outfd.fd == -1) {
155 			err = got_error(GOT_ERR_PRIVSEP_NO_FD);
156 			goto done;
157 		}
158 
159 		err = got_object_read_header(&obj, imsg.fd);
160 		if (err)
161 			goto done;
162 
163 		if (lseek(imsg.fd, SEEK_SET, 0) == -1) {
164 			err = got_error_from_errno("lseek");
165 			goto done;
166 		}
167 
168 		f = fdopen(imsg.fd, "rb");
169 		if (f == NULL) {
170 			err = got_error_from_errno("fdopen");
171 			goto done;
172 		}
173 
174 		if (obj->size + obj->hdrlen <=
175 		    GOT_PRIVSEP_INLINE_BLOB_DATA_MAX) {
176 			err = got_inflate_to_mem(&buf, &size, NULL, &csum, f);
177 			if (err)
178 				goto done;
179 		} else {
180 			err = got_inflate_to_fd(&size, f, &csum, imsg_outfd.fd);
181 			if (err)
182 				goto done;
183 		}
184 		SHA1Final(id.sha1, &sha1_ctx);
185 		if (memcmp(expected_id.sha1, id.sha1, SHA1_DIGEST_LENGTH) != 0) {
186 			char buf[SHA1_DIGEST_STRING_LENGTH];
187 			err = got_error_fmt(GOT_ERR_OBJ_CSUM,
188 			    "checksum failure for object %s",
189 			    got_sha1_digest_to_str(expected_id.sha1, buf,
190 			    sizeof(buf)));
191 			goto done;
192 		}
193 
194 		if (size < obj->hdrlen) {
195 			err = got_error(GOT_ERR_BAD_OBJ_HDR);
196 			goto done;
197 		}
198 
199 		err = got_privsep_send_blob(&ibuf, size, obj->hdrlen, buf);
200 done:
201 		free(buf);
202 		if (f) {
203 			if (fclose(f) == EOF && err == NULL)
204 				err = got_error_from_errno("fclose");
205 		} else if (imsg.fd != -1) {
206 			if (close(imsg.fd) == -1 && err == NULL)
207 				err = got_error_from_errno("close");
208 		}
209 		if (imsg_outfd.fd != -1) {
210 			if (close(imsg_outfd.fd) == -1 && err == NULL)
211 				err = got_error_from_errno("close");
212 		}
213 
214 		imsg_free(&imsg);
215 		imsg_free(&imsg_outfd);
216 		if (obj)
217 			got_object_close(obj);
218 		if (err)
219 			break;
220 	}
221 
222 	imsg_clear(&ibuf);
223 	if (err) {
224 		if (!sigint_received && err->code != GOT_ERR_PRIVSEP_PIPE) {
225 			fprintf(stderr, "%s: %s\n", getprogname(), err->msg);
226 			got_privsep_send_error(&ibuf, err);
227 		}
228 	}
229 	if (close(GOT_IMSG_FD_CHILD) == -1 && err == NULL)
230 		err = got_error_from_errno("close");
231 	return err ? 1 : 0;
232 }