1 /* $OpenBSD: imsg.c,v 1.23 2023/12/12 15:47:41 claudio Exp $ */
2
3 /*
4 * Copyright (c) 2023 Claudio Jeker <claudio@openbsd.org>
5 * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
6 *
7 * Permission to use, copy, modify, and distribute this software for any
8 * purpose with or without fee is hereby granted, provided that the above
9 * copyright notice and this permission notice appear in all copies.
10 *
11 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
13 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
15 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
16 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
17 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
18 */
19
20 #include <sys/types.h>
21 #include <sys/socket.h>
22 #include <sys/uio.h>
23
24 #include <errno.h>
25 #include <stdlib.h>
26 #include <string.h>
27 #include <unistd.h>
28
29 #include "compat.h"
30 #include "imsg.h"
31
32 struct imsg_fd {
33 TAILQ_ENTRY(imsg_fd) entry;
34 int fd;
35 };
36
37 int imsg_fd_overhead = 0;
38
39 static int imsg_dequeue_fd(struct imsgbuf *);
40
41 void
imsg_init(struct imsgbuf * imsgbuf,int fd)42 imsg_init(struct imsgbuf *imsgbuf, int fd)
43 {
44 msgbuf_init(&imsgbuf->w);
45 memset(&imsgbuf->r, 0, sizeof(imsgbuf->r));
46 imsgbuf->fd = fd;
47 imsgbuf->w.fd = fd;
48 imsgbuf->pid = getpid();
49 TAILQ_INIT(&imsgbuf->fds);
50 }
51
52 ssize_t
imsg_read(struct imsgbuf * imsgbuf)53 imsg_read(struct imsgbuf *imsgbuf)
54 {
55 struct msghdr msg;
56 struct cmsghdr *cmsg;
57 union {
58 struct cmsghdr hdr;
59 char buf[CMSG_SPACE(sizeof(int) * 1)];
60 } cmsgbuf;
61 struct iovec iov;
62 ssize_t n = -1;
63 int fd;
64 struct imsg_fd *ifd;
65
66 memset(&msg, 0, sizeof(msg));
67 memset(&cmsgbuf, 0, sizeof(cmsgbuf));
68
69 iov.iov_base = imsgbuf->r.buf + imsgbuf->r.wpos;
70 iov.iov_len = sizeof(imsgbuf->r.buf) - imsgbuf->r.wpos;
71 msg.msg_iov = &iov;
72 msg.msg_iovlen = 1;
73 msg.msg_control = &cmsgbuf.buf;
74 msg.msg_controllen = CMSG_SPACE(sizeof(int) * 16);
75
76 if ((ifd = calloc(1, sizeof(struct imsg_fd))) == NULL)
77 return (-1);
78
79 again:
80 if (getdtablecount() + imsg_fd_overhead +
81 (int)((CMSG_SPACE(sizeof(int))-CMSG_SPACE(0))/sizeof(int))
82 >= getdtablesize()) {
83 errno = EAGAIN;
84 free(ifd);
85 return (-1);
86 }
87
88 if ((n = recvmsg(imsgbuf->fd, &msg, 0)) == -1) {
89 if (errno == EINTR)
90 goto again;
91 goto fail;
92 }
93
94 imsgbuf->r.wpos += n;
95
96 for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL;
97 cmsg = CMSG_NXTHDR(&msg, cmsg)) {
98 if (cmsg->cmsg_level == SOL_SOCKET &&
99 cmsg->cmsg_type == SCM_RIGHTS) {
100 int i;
101 int j;
102
103 /*
104 * We only accept one file descriptor. Due to C
105 * padding rules, our control buffer might contain
106 * more than one fd, and we must close them.
107 */
108 j = ((char *)cmsg + cmsg->cmsg_len -
109 (char *)CMSG_DATA(cmsg)) / sizeof(int);
110 for (i = 0; i < j; i++) {
111 fd = ((int *)CMSG_DATA(cmsg))[i];
112 if (ifd != NULL) {
113 ifd->fd = fd;
114 TAILQ_INSERT_TAIL(&imsgbuf->fds, ifd,
115 entry);
116 ifd = NULL;
117 } else
118 close(fd);
119 }
120 }
121 /* we do not handle other ctl data level */
122 }
123
124 fail:
125 free(ifd);
126 return (n);
127 }
128
129 ssize_t
imsg_get(struct imsgbuf * imsgbuf,struct imsg * imsg)130 imsg_get(struct imsgbuf *imsgbuf, struct imsg *imsg)
131 {
132 struct imsg m;
133 size_t av, left, datalen;
134
135 av = imsgbuf->r.wpos;
136
137 if (IMSG_HEADER_SIZE > av)
138 return (0);
139
140 memcpy(&m.hdr, imsgbuf->r.buf, sizeof(m.hdr));
141 if (m.hdr.len < IMSG_HEADER_SIZE ||
142 m.hdr.len > MAX_IMSGSIZE) {
143 errno = ERANGE;
144 return (-1);
145 }
146 if (m.hdr.len > av)
147 return (0);
148
149 m.fd = -1;
150 m.buf = NULL;
151 m.data = NULL;
152
153 datalen = m.hdr.len - IMSG_HEADER_SIZE;
154 imsgbuf->r.rptr = imsgbuf->r.buf + IMSG_HEADER_SIZE;
155 if (datalen != 0) {
156 if ((m.buf = ibuf_open(datalen)) == NULL)
157 return (-1);
158 if (ibuf_add(m.buf, imsgbuf->r.rptr, datalen) == -1) {
159 /* this should never fail */
160 ibuf_free(m.buf);
161 return (-1);
162 }
163 m.data = ibuf_data(m.buf);
164 }
165
166 if (m.hdr.flags & IMSGF_HASFD)
167 m.fd = imsg_dequeue_fd(imsgbuf);
168
169 if (m.hdr.len < av) {
170 left = av - m.hdr.len;
171 memmove(&imsgbuf->r.buf, imsgbuf->r.buf + m.hdr.len, left);
172 imsgbuf->r.wpos = left;
173 } else
174 imsgbuf->r.wpos = 0;
175
176 *imsg = m;
177 return (datalen + IMSG_HEADER_SIZE);
178 }
179
180 int
imsg_get_ibuf(struct imsg * imsg,struct ibuf * ibuf)181 imsg_get_ibuf(struct imsg *imsg, struct ibuf *ibuf)
182 {
183 if (imsg->buf == NULL) {
184 errno = EBADMSG;
185 return (-1);
186 }
187 return ibuf_get_ibuf(imsg->buf, ibuf_size(imsg->buf), ibuf);
188 }
189
190 int
imsg_get_data(struct imsg * imsg,void * data,size_t len)191 imsg_get_data(struct imsg *imsg, void *data, size_t len)
192 {
193 if (len == 0) {
194 errno = EINVAL;
195 return (-1);
196 }
197 if (imsg->buf == NULL || ibuf_size(imsg->buf) != len) {
198 errno = EBADMSG;
199 return (-1);
200 }
201 return ibuf_get(imsg->buf, data, len);
202 }
203
204 int
imsg_get_fd(struct imsg * imsg)205 imsg_get_fd(struct imsg *imsg)
206 {
207 int fd = imsg->fd;
208
209 imsg->fd = -1;
210 return fd;
211 }
212
213 uint32_t
imsg_get_id(struct imsg * imsg)214 imsg_get_id(struct imsg *imsg)
215 {
216 return (imsg->hdr.peerid);
217 }
218
219 size_t
imsg_get_len(struct imsg * imsg)220 imsg_get_len(struct imsg *imsg)
221 {
222 if (imsg->buf == NULL)
223 return 0;
224 return ibuf_size(imsg->buf);
225 }
226
227 pid_t
imsg_get_pid(struct imsg * imsg)228 imsg_get_pid(struct imsg *imsg)
229 {
230 return (imsg->hdr.pid);
231 }
232
233 uint32_t
imsg_get_type(struct imsg * imsg)234 imsg_get_type(struct imsg *imsg)
235 {
236 return (imsg->hdr.type);
237 }
238
239 int
imsg_compose(struct imsgbuf * imsgbuf,uint32_t type,uint32_t id,pid_t pid,int fd,const void * data,size_t datalen)240 imsg_compose(struct imsgbuf *imsgbuf, uint32_t type, uint32_t id, pid_t pid,
241 int fd, const void *data, size_t datalen)
242 {
243 struct ibuf *wbuf;
244
245 if ((wbuf = imsg_create(imsgbuf, type, id, pid, datalen)) == NULL)
246 return (-1);
247
248 if (imsg_add(wbuf, data, datalen) == -1)
249 return (-1);
250
251 ibuf_fd_set(wbuf, fd);
252 imsg_close(imsgbuf, wbuf);
253
254 return (1);
255 }
256
257 int
imsg_composev(struct imsgbuf * imsgbuf,uint32_t type,uint32_t id,pid_t pid,int fd,const struct iovec * iov,int iovcnt)258 imsg_composev(struct imsgbuf *imsgbuf, uint32_t type, uint32_t id, pid_t pid,
259 int fd, const struct iovec *iov, int iovcnt)
260 {
261 struct ibuf *wbuf;
262 int i;
263 size_t datalen = 0;
264
265 for (i = 0; i < iovcnt; i++)
266 datalen += iov[i].iov_len;
267
268 if ((wbuf = imsg_create(imsgbuf, type, id, pid, datalen)) == NULL)
269 return (-1);
270
271 for (i = 0; i < iovcnt; i++)
272 if (imsg_add(wbuf, iov[i].iov_base, iov[i].iov_len) == -1)
273 return (-1);
274
275 ibuf_fd_set(wbuf, fd);
276 imsg_close(imsgbuf, wbuf);
277
278 return (1);
279 }
280
281 /*
282 * Enqueue imsg with payload from ibuf buf. fd passing is not possible
283 * with this function.
284 */
285 int
imsg_compose_ibuf(struct imsgbuf * imsgbuf,uint32_t type,uint32_t id,pid_t pid,struct ibuf * buf)286 imsg_compose_ibuf(struct imsgbuf *imsgbuf, uint32_t type, uint32_t id,
287 pid_t pid, struct ibuf *buf)
288 {
289 struct ibuf *hdrbuf = NULL;
290 struct imsg_hdr hdr;
291 int save_errno;
292
293 if (ibuf_size(buf) + IMSG_HEADER_SIZE > MAX_IMSGSIZE) {
294 errno = ERANGE;
295 goto fail;
296 }
297
298 hdr.type = type;
299 hdr.len = ibuf_size(buf) + IMSG_HEADER_SIZE;
300 hdr.flags = 0;
301 hdr.peerid = id;
302 if ((hdr.pid = pid) == 0)
303 hdr.pid = imsgbuf->pid;
304
305 if ((hdrbuf = ibuf_open(IMSG_HEADER_SIZE)) == NULL)
306 goto fail;
307 if (imsg_add(hdrbuf, &hdr, sizeof(hdr)) == -1)
308 goto fail;
309
310 ibuf_close(&imsgbuf->w, hdrbuf);
311 ibuf_close(&imsgbuf->w, buf);
312 return (1);
313
314 fail:
315 save_errno = errno;
316 ibuf_free(buf);
317 ibuf_free(hdrbuf);
318 errno = save_errno;
319 return (-1);
320 }
321
322 /*
323 * Forward imsg to another channel. Any attached fd is closed.
324 */
325 int
imsg_forward(struct imsgbuf * imsgbuf,struct imsg * msg)326 imsg_forward(struct imsgbuf *imsgbuf, struct imsg *msg)
327 {
328 struct ibuf *wbuf;
329 size_t len = 0;
330
331 if (msg->fd != -1) {
332 close(msg->fd);
333 msg->fd = -1;
334 }
335
336 if (msg->buf != NULL) {
337 ibuf_rewind(msg->buf);
338 len = ibuf_size(msg->buf);
339 }
340
341 if ((wbuf = imsg_create(imsgbuf, msg->hdr.type, msg->hdr.peerid,
342 msg->hdr.pid, len)) == NULL)
343 return (-1);
344
345 if (msg->buf != NULL) {
346 if (ibuf_add_buf(wbuf, msg->buf) == -1) {
347 ibuf_free(wbuf);
348 return (-1);
349 }
350 }
351
352 imsg_close(imsgbuf, wbuf);
353 return (1);
354 }
355
356 struct ibuf *
imsg_create(struct imsgbuf * imsgbuf,uint32_t type,uint32_t id,pid_t pid,size_t datalen)357 imsg_create(struct imsgbuf *imsgbuf, uint32_t type, uint32_t id, pid_t pid,
358 size_t datalen)
359 {
360 struct ibuf *wbuf;
361 struct imsg_hdr hdr;
362
363 datalen += IMSG_HEADER_SIZE;
364 if (datalen > MAX_IMSGSIZE) {
365 errno = ERANGE;
366 return (NULL);
367 }
368
369 hdr.type = type;
370 hdr.flags = 0;
371 hdr.peerid = id;
372 if ((hdr.pid = pid) == 0)
373 hdr.pid = imsgbuf->pid;
374 if ((wbuf = ibuf_dynamic(datalen, MAX_IMSGSIZE)) == NULL) {
375 return (NULL);
376 }
377 if (imsg_add(wbuf, &hdr, sizeof(hdr)) == -1)
378 return (NULL);
379
380 return (wbuf);
381 }
382
383 int
imsg_add(struct ibuf * msg,const void * data,size_t datalen)384 imsg_add(struct ibuf *msg, const void *data, size_t datalen)
385 {
386 if (datalen)
387 if (ibuf_add(msg, data, datalen) == -1) {
388 ibuf_free(msg);
389 return (-1);
390 }
391 return (datalen);
392 }
393
394 void
imsg_close(struct imsgbuf * imsgbuf,struct ibuf * msg)395 imsg_close(struct imsgbuf *imsgbuf, struct ibuf *msg)
396 {
397 struct imsg_hdr *hdr;
398
399 hdr = (struct imsg_hdr *)msg->buf;
400
401 hdr->flags &= ~IMSGF_HASFD;
402 if (ibuf_fd_avail(msg))
403 hdr->flags |= IMSGF_HASFD;
404 hdr->len = ibuf_size(msg);
405
406 ibuf_close(&imsgbuf->w, msg);
407 }
408
409 void
imsg_free(struct imsg * imsg)410 imsg_free(struct imsg *imsg)
411 {
412 ibuf_free(imsg->buf);
413 }
414
415 static int
imsg_dequeue_fd(struct imsgbuf * imsgbuf)416 imsg_dequeue_fd(struct imsgbuf *imsgbuf)
417 {
418 int fd;
419 struct imsg_fd *ifd;
420
421 if ((ifd = TAILQ_FIRST(&imsgbuf->fds)) == NULL)
422 return (-1);
423
424 fd = ifd->fd;
425 TAILQ_REMOVE(&imsgbuf->fds, ifd, entry);
426 free(ifd);
427
428 return (fd);
429 }
430
431 int
imsg_flush(struct imsgbuf * imsgbuf)432 imsg_flush(struct imsgbuf *imsgbuf)
433 {
434 while (imsgbuf->w.queued)
435 if (msgbuf_write(&imsgbuf->w) <= 0)
436 return (-1);
437 return (0);
438 }
439
440 void
imsg_clear(struct imsgbuf * imsgbuf)441 imsg_clear(struct imsgbuf *imsgbuf)
442 {
443 int fd;
444
445 msgbuf_clear(&imsgbuf->w);
446 while ((fd = imsg_dequeue_fd(imsgbuf)) != -1)
447 close(fd);
448 }
449