1 /*
2  * Copyright (c) 2018 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/queue.h>
19 #include <sys/uio.h>
20 
21 #include <stdio.h>
22 #include <stdlib.h>
23 #include <string.h>
24 #include <errno.h>
25 #include <stdint.h>
26 #include <poll.h>
27 #include <imsg.h>
28 #include <sha1.h>
29 #include <zlib.h>
30 
31 #include "got_object.h"
32 #include "got_error.h"
33 
34 #include "got_lib_sha1.h"
35 #include "got_lib_delta.h"
36 #include "got_lib_zbuf.h"
37 #include "got_lib_object.h"
38 #include "got_lib_privsep.h"
39 
40 #ifndef MIN
41 #define	MIN(_a,_b) ((_a) < (_b) ? (_a) : (_b))
42 #endif
43 
44 static const struct got_error *
45 poll_fd(int fd, int events, int timeout)
46 {
47 	struct pollfd pfd[1];
48 	int n;
49 
50 	pfd[0].fd = fd;
51 	pfd[0].events = events;
52 
53 	n = poll(pfd, 1, timeout);
54 	if (n == -1)
55 		return got_error_from_errno();
56 	if (n == 0)
57 		return got_error(GOT_ERR_TIMEOUT);
58 	if (pfd[0].revents & (POLLERR | POLLNVAL))
59 		return got_error_from_errno();
60 	if (pfd[0].revents & (events | POLLHUP))
61 		return NULL;
62 
63 	return got_error(GOT_ERR_INTERRUPT);
64 }
65 
66 static const struct got_error *
67 recv_one_imsg(struct imsg *imsg, struct imsgbuf *ibuf, size_t min_datalen)
68 {
69 	const struct got_error *err;
70 	ssize_t n, m;
71 
72 	err = poll_fd(ibuf->fd, POLLIN, INFTIM);
73 	if (err)
74 		return err;
75 
76 	n = imsg_read(ibuf);
77 	if (n == -1) {
78 		if (errno == EAGAIN) /* Could be a file-descriptor leak. */
79 			return got_error(GOT_ERR_PRIVSEP_NO_FD);
80 		return got_error(GOT_ERR_PRIVSEP_READ);
81 	}
82 	if (n == 0)
83 		return got_error(GOT_ERR_PRIVSEP_PIPE);
84 
85 	m = imsg_get(ibuf, imsg);
86 	if (m == 0)
87 		return got_error(GOT_ERR_PRIVSEP_READ);
88 
89 	if (imsg->hdr.len < IMSG_HEADER_SIZE + min_datalen)
90 		return got_error(GOT_ERR_PRIVSEP_LEN);
91 
92 	return NULL;
93 }
94 
95 static const struct got_error *
96 recv_imsg_error(struct imsg *imsg, size_t datalen)
97 {
98 	struct got_imsg_error ierr;
99 
100 	if (datalen != sizeof(ierr))
101 		return got_error(GOT_ERR_PRIVSEP_LEN);
102 
103 	memcpy(&ierr, imsg->data, sizeof(ierr));
104 	if (ierr.code == GOT_ERR_ERRNO) {
105 		static struct got_error serr;
106 		serr.code = GOT_ERR_ERRNO;
107 		serr.msg = strerror(ierr.errno_code);
108 		return &serr;
109 	}
110 
111 	return got_error(ierr.code);
112 }
113 
114 /* Attempt to send an error in an imsg. Complain on stderr as a last resort. */
115 void
116 got_privsep_send_error(struct imsgbuf *ibuf, const struct got_error *err)
117 {
118 	const struct got_error *poll_err;
119 	struct got_imsg_error ierr;
120 	int ret;
121 
122 	ierr.code = err->code;
123 	if (err->code == GOT_ERR_ERRNO)
124 		ierr.errno_code = errno;
125 	else
126 		ierr.errno_code = 0;
127 	ret = imsg_compose(ibuf, GOT_IMSG_ERROR, 0, 0, -1, &ierr, sizeof(ierr));
128 	if (ret != -1) {
129 		fprintf(stderr, "%s: error %d \"%s\": imsg_compose: %s\n",
130 		    getprogname(), err->code, err->msg, strerror(errno));
131 	}
132 
133 	poll_err = poll_fd(ibuf->fd, POLLOUT, INFTIM);
134 	if (poll_err)
135 		fprintf(stderr, "%s: error %d \"%s\": poll: %s\n",
136 		    getprogname(), err->code, err->msg, poll_err->msg);
137 
138 	ret = imsg_flush(ibuf);
139 	if (ret == -1)
140 		fprintf(stderr, "%s: error %d \"%s\": imsg_flush: %s\n",
141 		    getprogname(), err->code, err->msg, strerror(errno));
142 }
143 
144 const struct got_error *
145 got_privsep_send_obj(struct imsgbuf *ibuf, struct got_object *obj, int ndeltas)
146 {
147 	const struct got_error *err = NULL;
148 	struct got_imsg_object iobj;
149 
150 	iobj.type = obj->type;
151 	iobj.flags = obj->flags;
152 	iobj.hdrlen = obj->hdrlen;
153 	iobj.size = obj->size;
154 	iobj.ndeltas = ndeltas;
155 
156 	if (ndeltas > 0) {
157 		/* TODO: Handle deltas */
158 	}
159 
160 	if (imsg_compose(ibuf, GOT_IMSG_OBJECT, 0, 0, -1, &iobj, sizeof(iobj))
161 	    == -1)
162 		return got_error_from_errno();
163 
164 	err = poll_fd(ibuf->fd, POLLOUT, INFTIM);
165 	if (err)
166 		return err;
167 
168 	if (imsg_flush(ibuf) == -1)
169 		return got_error_from_errno();
170 
171 	return NULL;
172 }
173 
174 const struct got_error *
175 got_privsep_recv_obj(struct got_object **obj, struct imsgbuf *ibuf)
176 {
177 	const struct got_error *err = NULL;
178 	struct imsg imsg;
179 	struct got_imsg_object iobj;
180 	size_t datalen;
181 	int i;
182 	const size_t min_datalen =
183 	    MIN(sizeof(struct got_imsg_error), sizeof(struct got_imsg_object));
184 
185 	*obj = NULL;
186 
187 	err = recv_one_imsg(&imsg, ibuf, min_datalen);
188 	if (err)
189 		return err;
190 
191 	datalen = imsg.hdr.len - IMSG_HEADER_SIZE;
192 
193 	switch (imsg.hdr.type) {
194 	case GOT_IMSG_ERROR:
195 		err = recv_imsg_error(&imsg, datalen);
196 		break;
197 	case GOT_IMSG_OBJECT:
198 		if (datalen != sizeof(iobj)) {
199 			err = got_error(GOT_ERR_PRIVSEP_LEN);
200 			break;
201 		}
202 
203 		memcpy(&iobj, imsg.data, sizeof(iobj));
204 		if (iobj.ndeltas < 0 ||
205 		    iobj.ndeltas > GOT_DELTA_CHAIN_RECURSION_MAX) {
206 			err = got_error(GOT_ERR_PRIVSEP_LEN);
207 			break;
208 		}
209 
210 		*obj = calloc(1, sizeof(**obj));
211 		if (*obj == NULL) {
212 			err = got_error_from_errno();
213 			break;
214 		}
215 
216 		(*obj)->type = iobj.type;
217 		(*obj)->hdrlen = iobj.hdrlen;
218 		(*obj)->size = iobj.size;
219 		for (i = 0; i < iobj.ndeltas; i++) {
220 			/* TODO: Handle deltas */
221 		}
222 		break;
223 	default:
224 		err = got_error(GOT_ERR_PRIVSEP_MSG);
225 		break;
226 	}
227 
228 	imsg_free(&imsg);
229 
230 	return err;
231 }