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 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 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 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 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 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 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 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 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