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/cdefs.h> 30 __FBSDID("$FreeBSD$"); 31 32 #include <sys/param.h> 33 #include <sys/conf.h> 34 #include <sys/fcntl.h> 35 #include <sys/filio.h> 36 #include <sys/kernel.h> 37 #include <sys/malloc.h> 38 #include <sys/module.h> 39 #include <sys/poll.h> 40 #include <sys/proc.h> 41 #include <sys/snoop.h> 42 #include <sys/sx.h> 43 #include <sys/systm.h> 44 #include <sys/tty.h> 45 #include <sys/uio.h> 46 47 static struct cdev *snp_dev; 48 static MALLOC_DEFINE(M_SNP, "snp", "tty snoop device"); 49 50 /* XXX: should be mtx, but TTY can be locked by Giant. */ 51 #if 0 52 static struct mtx snp_register_lock; 53 MTX_SYSINIT(snp_register_lock, &snp_register_lock, 54 "tty snoop registration", MTX_DEF); 55 #define SNP_LOCK() mtx_lock(&snp_register_lock) 56 #define SNP_UNLOCK() mtx_unlock(&snp_register_lock) 57 #else 58 static struct sx snp_register_lock; 59 SX_SYSINIT(snp_register_lock, &snp_register_lock, 60 "tty snoop registration"); 61 #define SNP_LOCK() sx_xlock(&snp_register_lock) 62 #define SNP_UNLOCK() sx_xunlock(&snp_register_lock) 63 #endif 64 65 #define SNPGTYY_32DEV _IOR('T', 89, uint32_t) 66 67 /* 68 * There is no need to have a big input buffer. In most typical setups, 69 * we won't inject much data into the TTY, because users can't type 70 * really fast. 71 */ 72 #define SNP_INPUT_BUFSIZE 16 73 /* 74 * The output buffer has to be really big. Right now we don't support 75 * any form of flow control, which means we lost any data we can't 76 * accept. We set the output buffer size to about twice the size of a 77 * pseudo-terminal/virtual console's output buffer. 78 */ 79 #define SNP_OUTPUT_BUFSIZE 16384 80 81 static d_open_t snp_open; 82 static d_read_t snp_read; 83 static d_write_t snp_write; 84 static d_ioctl_t snp_ioctl; 85 static d_poll_t snp_poll; 86 87 static struct cdevsw snp_cdevsw = { 88 .d_version = D_VERSION, 89 .d_open = snp_open, 90 .d_read = snp_read, 91 .d_write = snp_write, 92 .d_ioctl = snp_ioctl, 93 .d_poll = snp_poll, 94 .d_name = "snp", 95 }; 96 97 static th_getc_capture_t snp_getc_capture; 98 99 static struct ttyhook snp_hook = { 100 .th_getc_capture = snp_getc_capture, 101 }; 102 103 /* 104 * Per-instance structure. 105 * 106 * List of locks 107 * (r) locked by snp_register_lock on assignment 108 * (t) locked by tty_lock 109 */ 110 struct snp_softc { 111 struct tty *snp_tty; /* (r) TTY we're snooping. */ 112 struct ttyoutq snp_outq; /* (t) Output queue. */ 113 struct cv snp_outwait; /* (t) Output wait queue. */ 114 struct selinfo snp_outpoll; /* (t) Output polling. */ 115 }; 116 117 static void 118 snp_dtor(void *data) 119 { 120 struct snp_softc *ss = data; 121 struct tty *tp; 122 123 tp = ss->snp_tty; 124 if (tp != NULL) { 125 tty_lock(tp); 126 ttyoutq_free(&ss->snp_outq); 127 ttyhook_unregister(tp); 128 ss->snp_tty = NULL; 129 } 130 131 cv_destroy(&ss->snp_outwait); 132 free(ss, M_SNP); 133 } 134 135 /* 136 * Snoop device node routines. 137 */ 138 139 static int 140 snp_open(struct cdev *dev, int flag, int mode, struct thread *td) 141 { 142 struct snp_softc *ss; 143 144 /* Allocate per-snoop data. */ 145 ss = malloc(sizeof(struct snp_softc), M_SNP, M_WAITOK|M_ZERO); 146 cv_init(&ss->snp_outwait, "snp out"); 147 148 devfs_set_cdevpriv(ss, snp_dtor); 149 150 return (0); 151 } 152 153 static int 154 snp_read(struct cdev *dev, struct uio *uio, int flag) 155 { 156 int error, oresid = uio->uio_resid; 157 struct snp_softc *ss; 158 struct tty *tp; 159 160 if (uio->uio_resid == 0) 161 return (0); 162 163 error = devfs_get_cdevpriv((void **)&ss); 164 if (error != 0) 165 return (error); 166 167 tp = ss->snp_tty; 168 if (tp == NULL || tty_gone(tp)) 169 return (EIO); 170 171 tty_lock(tp); 172 for (;;) { 173 error = ttyoutq_read_uio(&ss->snp_outq, tp, uio); 174 if (error != 0 || uio->uio_resid != oresid) 175 break; 176 177 /* Wait for more data. */ 178 if (flag & O_NONBLOCK) { 179 error = EWOULDBLOCK; 180 break; 181 } 182 error = cv_wait_sig(&ss->snp_outwait, tty_getlock(tp)); 183 if (error != 0) 184 break; 185 if (tty_gone(tp)) { 186 error = EIO; 187 break; 188 } 189 } 190 tty_unlock(tp); 191 192 return (error); 193 } 194 195 static int 196 snp_write(struct cdev *dev, struct uio *uio, int flag) 197 { 198 struct snp_softc *ss; 199 struct tty *tp; 200 int error, len; 201 char in[SNP_INPUT_BUFSIZE]; 202 203 error = devfs_get_cdevpriv((void **)&ss); 204 if (error != 0) 205 return (error); 206 207 tp = ss->snp_tty; 208 if (tp == NULL || tty_gone(tp)) 209 return (EIO); 210 211 while (uio->uio_resid > 0) { 212 /* Read new data. */ 213 len = imin(uio->uio_resid, sizeof in); 214 error = uiomove(in, len, uio); 215 if (error != 0) 216 return (error); 217 218 tty_lock(tp); 219 220 /* Driver could have abandoned the TTY in the mean time. */ 221 if (tty_gone(tp)) { 222 tty_unlock(tp); 223 return (ENXIO); 224 } 225 226 /* 227 * Deliver data to the TTY. Ignore errors for now, 228 * because we shouldn't bail out when we're running 229 * close to the watermarks. 230 */ 231 ttydisc_rint_simple(tp, in, len); 232 ttydisc_rint_done(tp); 233 234 tty_unlock(tp); 235 } 236 237 return (0); 238 } 239 240 static int 241 snp_ioctl(struct cdev *dev, u_long cmd, caddr_t data, int flags, 242 struct thread *td) 243 { 244 struct snp_softc *ss; 245 struct tty *tp; 246 int error; 247 248 error = devfs_get_cdevpriv((void **)&ss); 249 if (error != 0) 250 return (error); 251 252 switch (cmd) { 253 case SNPSTTY: 254 /* Bind TTY to snoop instance. */ 255 SNP_LOCK(); 256 tp = ss->snp_tty; 257 if (tp != NULL) { 258 if (*(int *)data == -1) { 259 tty_lock(tp); 260 ss->snp_tty = NULL; 261 ttyoutq_free(&ss->snp_outq); 262 ttyhook_unregister(tp); 263 error = 0; 264 } else { 265 error = EBUSY; 266 } 267 SNP_UNLOCK(); 268 return (error); 269 } 270 /* 271 * XXXRW / XXXJA: no capability check here. 272 */ 273 error = ttyhook_register(&ss->snp_tty, td->td_proc, 274 *(int *)data, &snp_hook, ss); 275 SNP_UNLOCK(); 276 if (error != 0) 277 return (error); 278 279 /* Now that went okay, allocate a buffer for the queue. */ 280 tp = ss->snp_tty; 281 tty_lock(tp); 282 ttyoutq_setsize(&ss->snp_outq, tp, SNP_OUTPUT_BUFSIZE); 283 tty_unlock(tp); 284 285 return (0); 286 case SNPGTTY: 287 /* Obtain device number of associated TTY. */ 288 if (ss->snp_tty == NULL) 289 *(dev_t *)data = NODEV; 290 else 291 *(dev_t *)data = tty_udev(ss->snp_tty); 292 return (0); 293 case SNPGTYY_32DEV: 294 if (ss->snp_tty == NULL) 295 *(uint32_t *)data = -1; 296 else 297 *(uint32_t *)data = tty_udev(ss->snp_tty); /* trunc */ 298 return (0); 299 case FIONREAD: 300 tp = ss->snp_tty; 301 if (tp != NULL) { 302 tty_lock(tp); 303 if (tty_gone(tp)) 304 *(int *)data = SNP_TTYCLOSE; 305 else 306 *(int *)data = ttyoutq_bytesused(&ss->snp_outq); 307 tty_unlock(tp); 308 } else { 309 *(int *)data = SNP_DETACH; 310 } 311 return (0); 312 default: 313 return (ENOTTY); 314 } 315 } 316 317 static int 318 snp_poll(struct cdev *dev, int events, struct thread *td) 319 { 320 struct snp_softc *ss; 321 struct tty *tp; 322 int revents; 323 324 if (devfs_get_cdevpriv((void **)&ss) != 0) 325 return (events & 326 (POLLHUP|POLLIN|POLLRDNORM|POLLOUT|POLLWRNORM)); 327 328 revents = 0; 329 330 if (events & (POLLIN | POLLRDNORM)) { 331 tp = ss->snp_tty; 332 if (tp != NULL) { 333 tty_lock(tp); 334 if (ttyoutq_bytesused(&ss->snp_outq) > 0) 335 revents |= events & (POLLIN | POLLRDNORM); 336 tty_unlock(tp); 337 } 338 } 339 340 if (revents == 0) 341 selrecord(td, &ss->snp_outpoll); 342 343 return (revents); 344 } 345 346 /* 347 * TTY hook events. 348 */ 349 350 static int 351 snp_modevent(module_t mod, int type, void *data) 352 { 353 354 switch (type) { 355 case MOD_LOAD: 356 snp_dev = make_dev(&snp_cdevsw, 0, 357 UID_ROOT, GID_WHEEL, 0600, "snp"); 358 return (0); 359 case MOD_UNLOAD: 360 /* XXX: Make existing users leave. */ 361 destroy_dev(snp_dev); 362 return (0); 363 default: 364 return (EOPNOTSUPP); 365 } 366 } 367 368 static void 369 snp_getc_capture(struct tty *tp, const void *buf, size_t len) 370 { 371 struct snp_softc *ss = ttyhook_softc(tp); 372 373 ttyoutq_write(&ss->snp_outq, buf, len); 374 375 cv_broadcast(&ss->snp_outwait); 376 selwakeup(&ss->snp_outpoll); 377 } 378 379 static moduledata_t snp_mod = { 380 "snp", 381 snp_modevent, 382 NULL 383 }; 384 385 DECLARE_MODULE(snp, snp_mod, SI_SUB_DRIVERS, SI_ORDER_MIDDLE); 386