1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 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 } 129 130 cv_destroy(&ss->snp_outwait); 131 free(ss, M_SNP); 132 } 133 134 /* 135 * Snoop device node routines. 136 */ 137 138 static int 139 snp_open(struct cdev *dev, int flag, int mode, struct thread *td) 140 { 141 struct snp_softc *ss; 142 143 /* Allocate per-snoop data. */ 144 ss = malloc(sizeof(struct snp_softc), M_SNP, M_WAITOK|M_ZERO); 145 cv_init(&ss->snp_outwait, "snp out"); 146 147 devfs_set_cdevpriv(ss, snp_dtor); 148 149 return (0); 150 } 151 152 static int 153 snp_read(struct cdev *dev, struct uio *uio, int flag) 154 { 155 int error, oresid = uio->uio_resid; 156 struct snp_softc *ss; 157 struct tty *tp; 158 159 if (uio->uio_resid == 0) 160 return (0); 161 162 error = devfs_get_cdevpriv((void **)&ss); 163 if (error != 0) 164 return (error); 165 166 tp = ss->snp_tty; 167 if (tp == NULL || tty_gone(tp)) 168 return (EIO); 169 170 tty_lock(tp); 171 for (;;) { 172 error = ttyoutq_read_uio(&ss->snp_outq, tp, uio); 173 if (error != 0 || uio->uio_resid != oresid) 174 break; 175 176 /* Wait for more data. */ 177 if (flag & O_NONBLOCK) { 178 error = EWOULDBLOCK; 179 break; 180 } 181 error = cv_wait_sig(&ss->snp_outwait, tp->t_mtx); 182 if (error != 0) 183 break; 184 if (tty_gone(tp)) { 185 error = EIO; 186 break; 187 } 188 } 189 tty_unlock(tp); 190 191 return (error); 192 } 193 194 static int 195 snp_write(struct cdev *dev, struct uio *uio, int flag) 196 { 197 struct snp_softc *ss; 198 struct tty *tp; 199 int error, len; 200 char in[SNP_INPUT_BUFSIZE]; 201 202 error = devfs_get_cdevpriv((void **)&ss); 203 if (error != 0) 204 return (error); 205 206 tp = ss->snp_tty; 207 if (tp == NULL || tty_gone(tp)) 208 return (EIO); 209 210 while (uio->uio_resid > 0) { 211 /* Read new data. */ 212 len = imin(uio->uio_resid, sizeof in); 213 error = uiomove(in, len, uio); 214 if (error != 0) 215 return (error); 216 217 tty_lock(tp); 218 219 /* Driver could have abandoned the TTY in the mean time. */ 220 if (tty_gone(tp)) { 221 tty_unlock(tp); 222 return (ENXIO); 223 } 224 225 /* 226 * Deliver data to the TTY. Ignore errors for now, 227 * because we shouldn't bail out when we're running 228 * close to the watermarks. 229 */ 230 ttydisc_rint_simple(tp, in, len); 231 ttydisc_rint_done(tp); 232 233 tty_unlock(tp); 234 } 235 236 return (0); 237 } 238 239 static int 240 snp_ioctl(struct cdev *dev, u_long cmd, caddr_t data, int flags, 241 struct thread *td) 242 { 243 struct snp_softc *ss; 244 struct tty *tp; 245 int error; 246 247 error = devfs_get_cdevpriv((void **)&ss); 248 if (error != 0) 249 return (error); 250 251 switch (cmd) { 252 case SNPSTTY: 253 /* Bind TTY to snoop instance. */ 254 SNP_LOCK(); 255 if (ss->snp_tty != NULL) { 256 SNP_UNLOCK(); 257 return (EBUSY); 258 } 259 /* 260 * XXXRW / XXXJA: no capability check here. 261 */ 262 error = ttyhook_register(&ss->snp_tty, td->td_proc, 263 *(int *)data, &snp_hook, ss); 264 SNP_UNLOCK(); 265 if (error != 0) 266 return (error); 267 268 /* Now that went okay, allocate a buffer for the queue. */ 269 tp = ss->snp_tty; 270 tty_lock(tp); 271 ttyoutq_setsize(&ss->snp_outq, tp, SNP_OUTPUT_BUFSIZE); 272 tty_unlock(tp); 273 274 return (0); 275 case SNPGTTY: 276 /* Obtain device number of associated TTY. */ 277 if (ss->snp_tty == NULL) 278 *(dev_t *)data = NODEV; 279 else 280 *(dev_t *)data = tty_udev(ss->snp_tty); 281 return (0); 282 case SNPGTYY_32DEV: 283 if (ss->snp_tty == NULL) 284 *(uint32_t *)data = -1; 285 else 286 *(uint32_t *)data = tty_udev(ss->snp_tty); /* trunc */ 287 return (0); 288 case FIONREAD: 289 tp = ss->snp_tty; 290 if (tp != NULL) { 291 tty_lock(tp); 292 *(int *)data = ttyoutq_bytesused(&ss->snp_outq); 293 tty_unlock(tp); 294 } else { 295 *(int *)data = 0; 296 } 297 return (0); 298 default: 299 return (ENOTTY); 300 } 301 } 302 303 static int 304 snp_poll(struct cdev *dev, int events, struct thread *td) 305 { 306 struct snp_softc *ss; 307 struct tty *tp; 308 int revents; 309 310 if (devfs_get_cdevpriv((void **)&ss) != 0) 311 return (events & 312 (POLLHUP|POLLIN|POLLRDNORM|POLLOUT|POLLWRNORM)); 313 314 revents = 0; 315 316 if (events & (POLLIN | POLLRDNORM)) { 317 tp = ss->snp_tty; 318 if (tp != NULL) { 319 tty_lock(tp); 320 if (ttyoutq_bytesused(&ss->snp_outq) > 0) 321 revents |= events & (POLLIN | POLLRDNORM); 322 tty_unlock(tp); 323 } 324 } 325 326 if (revents == 0) 327 selrecord(td, &ss->snp_outpoll); 328 329 return (revents); 330 } 331 332 /* 333 * TTY hook events. 334 */ 335 336 static int 337 snp_modevent(module_t mod, int type, void *data) 338 { 339 340 switch (type) { 341 case MOD_LOAD: 342 snp_dev = make_dev(&snp_cdevsw, 0, 343 UID_ROOT, GID_WHEEL, 0600, "snp"); 344 return (0); 345 case MOD_UNLOAD: 346 /* XXX: Make existing users leave. */ 347 destroy_dev(snp_dev); 348 return (0); 349 default: 350 return (EOPNOTSUPP); 351 } 352 } 353 354 static void 355 snp_getc_capture(struct tty *tp, const void *buf, size_t len) 356 { 357 struct snp_softc *ss = ttyhook_softc(tp); 358 359 ttyoutq_write(&ss->snp_outq, buf, len); 360 361 cv_broadcast(&ss->snp_outwait); 362 selwakeup(&ss->snp_outpoll); 363 } 364 365 static moduledata_t snp_mod = { 366 "snp", 367 snp_modevent, 368 NULL 369 }; 370 371 DECLARE_MODULE(snp, snp_mod, SI_SUB_DRIVERS, SI_ORDER_MIDDLE); 372