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 /* Attempt to send an error in an imsg. Complain on stderr as a last resort. */
67 void
68 got_privsep_send_error(struct imsgbuf *ibuf, const struct got_error *err)
69 {
70 	const struct got_error *poll_err;
71 	struct got_imsg_error ierr;
72 	int ret;
73 
74 	ierr.code = err->code;
75 	if (err->code == GOT_ERR_ERRNO)
76 		ierr.errno_code = errno;
77 	else
78 		ierr.errno_code = 0;
79 	ret = imsg_compose(ibuf, GOT_IMSG_ERROR, 0, 0, -1, &ierr, sizeof(ierr));
80 	if (ret != -1) {
81 		fprintf(stderr, "%s: error %d \"%s\": imsg_compose: %s\n",
82 		    getprogname(), err->code, err->msg, strerror(errno));
83 	}
84 
85 	poll_err = poll_fd(ibuf->fd, POLLOUT, INFTIM);
86 	if (poll_err)
87 		fprintf(stderr, "%s: error %d \"%s\": poll: %s\n",
88 		    getprogname(), err->code, err->msg, poll_err->msg);
89 
90 	ret = imsg_flush(ibuf);
91 	if (ret == -1)
92 		fprintf(stderr, "%s: error %d \"%s\": imsg_flush: %s\n",
93 		    getprogname(), err->code, err->msg, strerror(errno));
94 }
95 
96 const struct got_error *
97 got_privsep_send_obj(struct imsgbuf *ibuf, struct got_object *obj, int ndeltas)
98 {
99 	const struct got_error *err = NULL;
100 	struct got_imsg_object iobj;
101 
102 	iobj.type = obj->type;
103 	iobj.flags = obj->flags;
104 	iobj.hdrlen = obj->hdrlen;
105 	iobj.size = obj->size;
106 	memcpy(iobj.id.sha1, obj->id.sha1, SHA1_DIGEST_LENGTH);
107 	iobj.ndeltas = ndeltas;
108 
109 	if (ndeltas > 0) {
110 		/* TODO: Handle deltas */
111 	}
112 
113 	if (imsg_compose(ibuf, GOT_IMSG_OBJECT, 0, 0, -1, &iobj, sizeof(iobj))
114 	    == -1)
115 		return got_error_from_errno();
116 
117 	err = poll_fd(ibuf->fd, POLLOUT, INFTIM);
118 	if (err)
119 		return err;
120 
121 	if (imsg_flush(ibuf) == -1)
122 		return got_error_from_errno();
123 
124 	return NULL;
125 }
126 
127 const struct got_error *
128 got_privsep_recv_obj(struct got_object **obj, struct imsgbuf *ibuf)
129 {
130 	const struct got_error *err = NULL;
131 	struct got_imsg_error ierr;
132 	struct imsg imsg;
133 	struct got_imsg_object iobj;
134 	ssize_t n, m;
135 	size_t datalen;
136 	int i;
137 
138 	*obj = NULL;
139 
140 	err = poll_fd(ibuf->fd, POLLIN, INFTIM);
141 	if (err)
142 		return err;
143 
144 	n = imsg_read(ibuf);
145 	if (n == -1) {
146 		if (errno == EAGAIN) /* Could be a file-descriptor leak. */
147 			return got_error(GOT_ERR_PRIVSEP_NO_FD);
148 		return got_error(GOT_ERR_PRIVSEP_READ);
149 	}
150 	if (n == 0)
151 		return got_error(GOT_ERR_PRIVSEP_PIPE);
152 
153 	m = imsg_get(ibuf, &imsg);
154 	if (m == 0)
155 		return got_error(GOT_ERR_PRIVSEP_READ);
156 
157 	if (imsg.hdr.len < IMSG_HEADER_SIZE + MIN(sizeof(ierr), sizeof(obj)))
158 		return got_error(GOT_ERR_PRIVSEP_LEN);
159 
160 	datalen = imsg.hdr.len - IMSG_HEADER_SIZE;
161 
162 	switch (imsg.hdr.type) {
163 	case GOT_IMSG_ERROR:
164 		if (datalen != sizeof(ierr)) {
165 			err = got_error(GOT_ERR_PRIVSEP_LEN);
166 			break;
167 		}
168 		memcpy(&ierr, imsg.data, sizeof(ierr));
169 		if (ierr.code == GOT_ERR_ERRNO) {
170 			static struct got_error serr;
171 			serr.code = GOT_ERR_ERRNO;
172 			serr.msg = strerror(ierr.errno_code);
173 			err = &serr;
174 		} else
175 			err = got_error(ierr.code);
176 		break;
177 	case GOT_IMSG_OBJECT:
178 		if (datalen != sizeof(iobj)) {
179 			err = got_error(GOT_ERR_PRIVSEP_LEN);
180 			break;
181 		}
182 
183 		memcpy(&iobj, imsg.data, sizeof(iobj));
184 		if (iobj.ndeltas < 0 ||
185 		    iobj.ndeltas > GOT_DELTA_CHAIN_RECURSION_MAX) {
186 			err = got_error(GOT_ERR_PRIVSEP_LEN);
187 			break;
188 		}
189 
190 		*obj = calloc(1, sizeof(**obj));
191 		if (*obj == NULL) {
192 			err = got_error_from_errno();
193 			break;
194 		}
195 
196 		(*obj)->type = iobj.type;
197 		(*obj)->hdrlen = iobj.hdrlen;
198 		(*obj)->size = iobj.size;
199 		memcpy((*obj)->id.sha1, iobj.id.sha1, SHA1_DIGEST_LENGTH);
200 		for (i = 0; i < iobj.ndeltas; i++) {
201 			/* TODO: Handle deltas */
202 		}
203 		break;
204 	}
205 
206 	imsg_free(&imsg);
207 
208 	return err;
209 }