1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2008 Ed Schouten <ed@FreeBSD.org>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #include <sys/param.h>
30 #include <sys/conf.h>
31 #include <sys/fcntl.h>
32 #include <sys/filio.h>
33 #include <sys/kernel.h>
34 #include <sys/malloc.h>
35 #include <sys/module.h>
36 #include <sys/poll.h>
37 #include <sys/proc.h>
38 #include <sys/snoop.h>
39 #include <sys/sx.h>
40 #include <sys/systm.h>
41 #include <sys/tty.h>
42 #include <sys/uio.h>
43
44 static struct cdev *snp_dev;
45 static MALLOC_DEFINE(M_SNP, "snp", "tty snoop device");
46
47 /* XXX: should be mtx, but TTY can be locked by Giant. */
48 #if 0
49 static struct mtx snp_register_lock;
50 MTX_SYSINIT(snp_register_lock, &snp_register_lock,
51 "tty snoop registration", MTX_DEF);
52 #define SNP_LOCK() mtx_lock(&snp_register_lock)
53 #define SNP_UNLOCK() mtx_unlock(&snp_register_lock)
54 #else
55 static struct sx snp_register_lock;
56 SX_SYSINIT(snp_register_lock, &snp_register_lock,
57 "tty snoop registration");
58 #define SNP_LOCK() sx_xlock(&snp_register_lock)
59 #define SNP_UNLOCK() sx_xunlock(&snp_register_lock)
60 #endif
61
62 #define SNPGTYY_32DEV _IOR('T', 89, uint32_t)
63
64 /*
65 * There is no need to have a big input buffer. In most typical setups,
66 * we won't inject much data into the TTY, because users can't type
67 * really fast.
68 */
69 #define SNP_INPUT_BUFSIZE 16
70 /*
71 * The output buffer has to be really big. Right now we don't support
72 * any form of flow control, which means we lost any data we can't
73 * accept. We set the output buffer size to about twice the size of a
74 * pseudo-terminal/virtual console's output buffer.
75 */
76 #define SNP_OUTPUT_BUFSIZE 16384
77
78 static d_open_t snp_open;
79 static d_read_t snp_read;
80 static d_write_t snp_write;
81 static d_ioctl_t snp_ioctl;
82 static d_poll_t snp_poll;
83
84 static struct cdevsw snp_cdevsw = {
85 .d_version = D_VERSION,
86 .d_open = snp_open,
87 .d_read = snp_read,
88 .d_write = snp_write,
89 .d_ioctl = snp_ioctl,
90 .d_poll = snp_poll,
91 .d_name = "snp",
92 };
93
94 static th_getc_capture_t snp_getc_capture;
95
96 static struct ttyhook snp_hook = {
97 .th_getc_capture = snp_getc_capture,
98 };
99
100 /*
101 * Per-instance structure.
102 *
103 * List of locks
104 * (r) locked by snp_register_lock on assignment
105 * (t) locked by tty_lock
106 */
107 struct snp_softc {
108 struct tty *snp_tty; /* (r) TTY we're snooping. */
109 struct ttyoutq snp_outq; /* (t) Output queue. */
110 struct cv snp_outwait; /* (t) Output wait queue. */
111 struct selinfo snp_outpoll; /* (t) Output polling. */
112 };
113
114 static void
snp_dtor(void * data)115 snp_dtor(void *data)
116 {
117 struct snp_softc *ss = data;
118 struct tty *tp;
119
120 tp = ss->snp_tty;
121 if (tp != NULL) {
122 tty_lock(tp);
123 ttyoutq_free(&ss->snp_outq);
124 ttyhook_unregister(tp);
125 ss->snp_tty = NULL;
126 }
127
128 cv_destroy(&ss->snp_outwait);
129 free(ss, M_SNP);
130 }
131
132 /*
133 * Snoop device node routines.
134 */
135
136 static int
snp_open(struct cdev * dev,int flag,int mode,struct thread * td)137 snp_open(struct cdev *dev, int flag, int mode, struct thread *td)
138 {
139 struct snp_softc *ss;
140
141 /* Allocate per-snoop data. */
142 ss = malloc(sizeof(struct snp_softc), M_SNP, M_WAITOK|M_ZERO);
143 cv_init(&ss->snp_outwait, "snp out");
144
145 devfs_set_cdevpriv(ss, snp_dtor);
146
147 return (0);
148 }
149
150 static int
snp_read(struct cdev * dev,struct uio * uio,int flag)151 snp_read(struct cdev *dev, struct uio *uio, int flag)
152 {
153 int error, oresid = uio->uio_resid;
154 struct snp_softc *ss;
155 struct tty *tp;
156
157 if (uio->uio_resid == 0)
158 return (0);
159
160 error = devfs_get_cdevpriv((void **)&ss);
161 if (error != 0)
162 return (error);
163
164 tp = ss->snp_tty;
165 if (tp == NULL || tty_gone(tp))
166 return (EIO);
167
168 tty_lock(tp);
169 for (;;) {
170 error = ttyoutq_read_uio(&ss->snp_outq, tp, uio);
171 if (error != 0 || uio->uio_resid != oresid)
172 break;
173
174 /* Wait for more data. */
175 if (flag & O_NONBLOCK) {
176 error = EWOULDBLOCK;
177 break;
178 }
179 error = cv_wait_sig(&ss->snp_outwait, tty_getlock(tp));
180 if (error != 0)
181 break;
182 if (tty_gone(tp)) {
183 error = EIO;
184 break;
185 }
186 }
187 tty_unlock(tp);
188
189 return (error);
190 }
191
192 static int
snp_write(struct cdev * dev,struct uio * uio,int flag)193 snp_write(struct cdev *dev, struct uio *uio, int flag)
194 {
195 struct snp_softc *ss;
196 struct tty *tp;
197 int error, len;
198 char in[SNP_INPUT_BUFSIZE];
199
200 error = devfs_get_cdevpriv((void **)&ss);
201 if (error != 0)
202 return (error);
203
204 tp = ss->snp_tty;
205 if (tp == NULL || tty_gone(tp))
206 return (EIO);
207
208 while (uio->uio_resid > 0) {
209 /* Read new data. */
210 len = imin(uio->uio_resid, sizeof in);
211 error = uiomove(in, len, uio);
212 if (error != 0)
213 return (error);
214
215 tty_lock(tp);
216
217 /* Driver could have abandoned the TTY in the mean time. */
218 if (tty_gone(tp)) {
219 tty_unlock(tp);
220 return (ENXIO);
221 }
222
223 /*
224 * Deliver data to the TTY. Ignore errors for now,
225 * because we shouldn't bail out when we're running
226 * close to the watermarks.
227 */
228 ttydisc_rint_simple(tp, in, len);
229 ttydisc_rint_done(tp);
230
231 tty_unlock(tp);
232 }
233
234 return (0);
235 }
236
237 static int
snp_ioctl(struct cdev * dev,u_long cmd,caddr_t data,int flags,struct thread * td)238 snp_ioctl(struct cdev *dev, u_long cmd, caddr_t data, int flags,
239 struct thread *td)
240 {
241 struct snp_softc *ss;
242 struct tty *tp;
243 int error;
244
245 error = devfs_get_cdevpriv((void **)&ss);
246 if (error != 0)
247 return (error);
248
249 switch (cmd) {
250 case SNPSTTY:
251 /* Bind TTY to snoop instance. */
252 SNP_LOCK();
253 tp = ss->snp_tty;
254 if (tp != NULL) {
255 if (*(int *)data == -1) {
256 tty_lock(tp);
257 ss->snp_tty = NULL;
258 ttyoutq_free(&ss->snp_outq);
259 ttyhook_unregister(tp);
260 error = 0;
261 } else {
262 error = EBUSY;
263 }
264 SNP_UNLOCK();
265 return (error);
266 }
267 /*
268 * XXXRW / XXXJA: no capability check here.
269 */
270 error = ttyhook_register(&ss->snp_tty, td->td_proc,
271 *(int *)data, &snp_hook, ss);
272 SNP_UNLOCK();
273 if (error != 0)
274 return (error);
275
276 /* Now that went okay, allocate a buffer for the queue. */
277 tp = ss->snp_tty;
278 tty_lock(tp);
279 ttyoutq_setsize(&ss->snp_outq, tp, SNP_OUTPUT_BUFSIZE);
280 tty_unlock(tp);
281
282 return (0);
283 case SNPGTTY:
284 /* Obtain device number of associated TTY. */
285 if (ss->snp_tty == NULL)
286 *(dev_t *)data = NODEV;
287 else
288 *(dev_t *)data = tty_udev(ss->snp_tty);
289 return (0);
290 case SNPGTYY_32DEV:
291 if (ss->snp_tty == NULL)
292 *(uint32_t *)data = -1;
293 else
294 *(uint32_t *)data = tty_udev(ss->snp_tty); /* trunc */
295 return (0);
296 case FIONREAD:
297 tp = ss->snp_tty;
298 if (tp != NULL) {
299 tty_lock(tp);
300 if (tty_gone(tp))
301 *(int *)data = SNP_TTYCLOSE;
302 else
303 *(int *)data = ttyoutq_bytesused(&ss->snp_outq);
304 tty_unlock(tp);
305 } else {
306 *(int *)data = SNP_DETACH;
307 }
308 return (0);
309 default:
310 return (ENOTTY);
311 }
312 }
313
314 static int
snp_poll(struct cdev * dev,int events,struct thread * td)315 snp_poll(struct cdev *dev, int events, struct thread *td)
316 {
317 struct snp_softc *ss;
318 struct tty *tp;
319 int revents;
320
321 if (devfs_get_cdevpriv((void **)&ss) != 0)
322 return (events &
323 (POLLHUP|POLLIN|POLLRDNORM|POLLOUT|POLLWRNORM));
324
325 revents = 0;
326
327 if (events & (POLLIN | POLLRDNORM)) {
328 tp = ss->snp_tty;
329 if (tp != NULL) {
330 tty_lock(tp);
331 if (ttyoutq_bytesused(&ss->snp_outq) > 0)
332 revents |= events & (POLLIN | POLLRDNORM);
333 tty_unlock(tp);
334 }
335 }
336
337 if (revents == 0)
338 selrecord(td, &ss->snp_outpoll);
339
340 return (revents);
341 }
342
343 /*
344 * TTY hook events.
345 */
346
347 static int
snp_modevent(module_t mod,int type,void * data)348 snp_modevent(module_t mod, int type, void *data)
349 {
350
351 switch (type) {
352 case MOD_LOAD:
353 snp_dev = make_dev(&snp_cdevsw, 0,
354 UID_ROOT, GID_WHEEL, 0600, "snp");
355 return (0);
356 case MOD_UNLOAD:
357 /* XXX: Make existing users leave. */
358 destroy_dev(snp_dev);
359 return (0);
360 default:
361 return (EOPNOTSUPP);
362 }
363 }
364
365 static void
snp_getc_capture(struct tty * tp,const void * buf,size_t len)366 snp_getc_capture(struct tty *tp, const void *buf, size_t len)
367 {
368 struct snp_softc *ss = ttyhook_softc(tp);
369
370 ttyoutq_write(&ss->snp_outq, buf, len);
371
372 cv_broadcast(&ss->snp_outwait);
373 selwakeup(&ss->snp_outpoll);
374 }
375
376 static moduledata_t snp_mod = {
377 "snp",
378 snp_modevent,
379 NULL
380 };
381
382 DECLARE_MODULE(snp, snp_mod, SI_SUB_DRIVERS, SI_ORDER_MIDDLE);
383