1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 3 * 4 * Copyright (c) 2008 Ed Schouten <ed@FreeBSD.org> 5 * All rights reserved. 6 * 7 * Portions of this software were developed under sponsorship from Snow 8 * B.V., the Netherlands. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 #include <sys/param.h> 33 #include <sys/kernel.h> 34 #include <sys/lock.h> 35 #include <sys/queue.h> 36 #include <sys/sysctl.h> 37 #include <sys/systm.h> 38 #include <sys/tty.h> 39 #include <sys/uio.h> 40 41 #include <vm/uma.h> 42 43 /* 44 * TTY input queue buffering. 45 * 46 * Unlike the output queue, the input queue has more features that are 47 * needed to properly implement various features offered by the TTY 48 * interface: 49 * 50 * - Data can be removed from the tail of the queue, which is used to 51 * implement backspace. 52 * - Once in a while, input has to be `canonicalized'. When ICANON is 53 * turned on, this will be done after a CR has been inserted. 54 * Otherwise, it should be done after any character has been inserted. 55 * - The input queue can store one bit per byte, called the quoting bit. 56 * This bit is used by TTYDISC to make backspace work on quoted 57 * characters. 58 * 59 * In most cases, there is probably less input than output, so unlike 60 * the outq, we'll stick to 128 byte blocks here. 61 */ 62 63 static int ttyinq_flush_secure = 1; 64 SYSCTL_INT(_kern, OID_AUTO, tty_inq_flush_secure, CTLFLAG_RW, 65 &ttyinq_flush_secure, 0, "Zero buffers while flushing"); 66 67 #define TTYINQ_QUOTESIZE (TTYINQ_DATASIZE / BMSIZE) 68 #define BMSIZE 32 69 #define GETBIT(tib,boff) \ 70 ((tib)->tib_quotes[(boff) / BMSIZE] & (1 << ((boff) % BMSIZE))) 71 #define SETBIT(tib,boff) \ 72 ((tib)->tib_quotes[(boff) / BMSIZE] |= (1 << ((boff) % BMSIZE))) 73 #define CLRBIT(tib,boff) \ 74 ((tib)->tib_quotes[(boff) / BMSIZE] &= ~(1 << ((boff) % BMSIZE))) 75 76 struct ttyinq_block { 77 struct ttyinq_block *tib_prev; 78 struct ttyinq_block *tib_next; 79 uint32_t tib_quotes[TTYINQ_QUOTESIZE]; 80 char tib_data[TTYINQ_DATASIZE]; 81 }; 82 83 static uma_zone_t ttyinq_zone; 84 85 #define TTYINQ_INSERT_TAIL(ti, tib) do { \ 86 if (ti->ti_end == 0) { \ 87 tib->tib_prev = NULL; \ 88 tib->tib_next = ti->ti_firstblock; \ 89 ti->ti_firstblock = tib; \ 90 } else { \ 91 tib->tib_prev = ti->ti_lastblock; \ 92 tib->tib_next = ti->ti_lastblock->tib_next; \ 93 ti->ti_lastblock->tib_next = tib; \ 94 } \ 95 if (tib->tib_next != NULL) \ 96 tib->tib_next->tib_prev = tib; \ 97 ti->ti_nblocks++; \ 98 } while (0) 99 100 #define TTYINQ_REMOVE_HEAD(ti) do { \ 101 ti->ti_firstblock = ti->ti_firstblock->tib_next; \ 102 if (ti->ti_firstblock != NULL) \ 103 ti->ti_firstblock->tib_prev = NULL; \ 104 ti->ti_nblocks--; \ 105 } while (0) 106 107 #define TTYINQ_RECYCLE(ti, tib) do { \ 108 if (ti->ti_quota <= ti->ti_nblocks) \ 109 uma_zfree(ttyinq_zone, tib); \ 110 else \ 111 TTYINQ_INSERT_TAIL(ti, tib); \ 112 } while (0) 113 114 int 115 ttyinq_setsize(struct ttyinq *ti, struct tty *tp, size_t size) 116 { 117 struct ttyinq_block *tib; 118 119 ti->ti_quota = howmany(size, TTYINQ_DATASIZE); 120 121 while (ti->ti_quota > ti->ti_nblocks) { 122 /* 123 * List is getting bigger. 124 * Add new blocks to the tail of the list. 125 * 126 * We must unlock the TTY temporarily, because we need 127 * to allocate memory. This won't be a problem, because 128 * in the worst case, another thread ends up here, which 129 * may cause us to allocate too many blocks, but this 130 * will be caught by the loop below. 131 */ 132 tty_unlock(tp); 133 tib = uma_zalloc(ttyinq_zone, M_WAITOK); 134 tty_lock(tp); 135 136 if (tty_gone(tp)) { 137 uma_zfree(ttyinq_zone, tib); 138 return (ENXIO); 139 } 140 141 TTYINQ_INSERT_TAIL(ti, tib); 142 } 143 return (0); 144 } 145 146 void 147 ttyinq_free(struct ttyinq *ti) 148 { 149 struct ttyinq_block *tib; 150 151 ttyinq_flush(ti); 152 ti->ti_quota = 0; 153 154 while ((tib = ti->ti_firstblock) != NULL) { 155 TTYINQ_REMOVE_HEAD(ti); 156 uma_zfree(ttyinq_zone, tib); 157 } 158 159 MPASS(ti->ti_nblocks == 0); 160 } 161 162 int 163 ttyinq_read_uio(struct ttyinq *ti, struct tty *tp, struct uio *uio, 164 size_t rlen, size_t flen) 165 { 166 167 MPASS(rlen <= uio->uio_resid); 168 169 while (rlen > 0) { 170 int error; 171 struct ttyinq_block *tib; 172 size_t cbegin, cend, clen; 173 174 /* See if there still is data. */ 175 if (ti->ti_begin == ti->ti_linestart) 176 return (0); 177 tib = ti->ti_firstblock; 178 if (tib == NULL) 179 return (0); 180 181 /* 182 * The end address should be the lowest of these three: 183 * - The write pointer 184 * - The blocksize - we can't read beyond the block 185 * - The end address if we could perform the full read 186 */ 187 cbegin = ti->ti_begin; 188 cend = MIN(MIN(ti->ti_linestart, ti->ti_begin + rlen), 189 TTYINQ_DATASIZE); 190 clen = cend - cbegin; 191 MPASS(clen >= flen); 192 rlen -= clen; 193 194 /* 195 * We can prevent buffering in some cases: 196 * - We need to read the block until the end. 197 * - We don't need to read the block until the end, but 198 * there is no data beyond it, which allows us to move 199 * the write pointer to a new block. 200 */ 201 if (cend == TTYINQ_DATASIZE || cend == ti->ti_end) { 202 /* 203 * Fast path: zero copy. Remove the first block, 204 * so we can unlock the TTY temporarily. 205 */ 206 TTYINQ_REMOVE_HEAD(ti); 207 ti->ti_begin = 0; 208 209 /* 210 * Because we remove the first block, we must 211 * fix up the block offsets. 212 */ 213 #define CORRECT_BLOCK(t) do { \ 214 if (t <= TTYINQ_DATASIZE) \ 215 t = 0; \ 216 else \ 217 t -= TTYINQ_DATASIZE; \ 218 } while (0) 219 CORRECT_BLOCK(ti->ti_linestart); 220 CORRECT_BLOCK(ti->ti_reprint); 221 CORRECT_BLOCK(ti->ti_end); 222 #undef CORRECT_BLOCK 223 224 /* 225 * Temporary unlock and copy the data to 226 * userspace. We may need to flush trailing 227 * bytes, like EOF characters. 228 */ 229 tty_unlock(tp); 230 error = uiomove(tib->tib_data + cbegin, 231 clen - flen, uio); 232 tty_lock(tp); 233 234 /* Block can now be readded to the list. */ 235 TTYINQ_RECYCLE(ti, tib); 236 } else { 237 char ob[TTYINQ_DATASIZE - 1]; 238 239 /* 240 * Slow path: store data in a temporary buffer. 241 */ 242 memcpy(ob, tib->tib_data + cbegin, clen - flen); 243 ti->ti_begin += clen; 244 MPASS(ti->ti_begin < TTYINQ_DATASIZE); 245 246 /* Temporary unlock and copy the data to userspace. */ 247 tty_unlock(tp); 248 error = uiomove(ob, clen - flen, uio); 249 tty_lock(tp); 250 } 251 252 if (error != 0) 253 return (error); 254 if (tty_gone(tp)) 255 return (ENXIO); 256 } 257 258 return (0); 259 } 260 261 static __inline void 262 ttyinq_set_quotes(struct ttyinq_block *tib, size_t offset, 263 size_t length, int value) 264 { 265 266 if (value) { 267 /* Set the bits. */ 268 for (; length > 0; length--, offset++) 269 SETBIT(tib, offset); 270 } else { 271 /* Unset the bits. */ 272 for (; length > 0; length--, offset++) 273 CLRBIT(tib, offset); 274 } 275 } 276 277 size_t 278 ttyinq_write(struct ttyinq *ti, const void *buf, size_t nbytes, int quote) 279 { 280 const char *cbuf = buf; 281 struct ttyinq_block *tib; 282 unsigned int boff; 283 size_t l; 284 285 while (nbytes > 0) { 286 boff = ti->ti_end % TTYINQ_DATASIZE; 287 288 if (ti->ti_end == 0) { 289 /* First time we're being used or drained. */ 290 MPASS(ti->ti_begin == 0); 291 tib = ti->ti_firstblock; 292 if (tib == NULL) { 293 /* Queue has no blocks. */ 294 break; 295 } 296 ti->ti_lastblock = tib; 297 } else if (boff == 0) { 298 /* We reached the end of this block on last write. */ 299 tib = ti->ti_lastblock->tib_next; 300 if (tib == NULL) { 301 /* We've reached the watermark. */ 302 break; 303 } 304 ti->ti_lastblock = tib; 305 } else { 306 tib = ti->ti_lastblock; 307 } 308 309 /* Don't copy more than was requested. */ 310 l = MIN(nbytes, TTYINQ_DATASIZE - boff); 311 MPASS(l > 0); 312 memcpy(tib->tib_data + boff, cbuf, l); 313 314 /* Set the quoting bits for the proper region. */ 315 ttyinq_set_quotes(tib, boff, l, quote); 316 317 cbuf += l; 318 nbytes -= l; 319 ti->ti_end += l; 320 } 321 322 return (cbuf - (const char *)buf); 323 } 324 325 int 326 ttyinq_write_nofrag(struct ttyinq *ti, const void *buf, size_t nbytes, int quote) 327 { 328 size_t ret __unused; 329 330 if (ttyinq_bytesleft(ti) < nbytes) 331 return (-1); 332 333 /* We should always be able to write it back. */ 334 ret = ttyinq_write(ti, buf, nbytes, quote); 335 MPASS(ret == nbytes); 336 337 return (0); 338 } 339 340 void 341 ttyinq_canonicalize(struct ttyinq *ti) 342 { 343 344 ti->ti_linestart = ti->ti_reprint = ti->ti_end; 345 ti->ti_startblock = ti->ti_reprintblock = ti->ti_lastblock; 346 } 347 348 size_t 349 ttyinq_findchar(struct ttyinq *ti, const char *breakc, size_t maxlen, 350 char *lastc) 351 { 352 struct ttyinq_block *tib = ti->ti_firstblock; 353 unsigned int boff = ti->ti_begin; 354 unsigned int bend = MIN(MIN(TTYINQ_DATASIZE, ti->ti_linestart), 355 ti->ti_begin + maxlen); 356 357 MPASS(maxlen > 0); 358 359 if (tib == NULL) 360 return (0); 361 362 while (boff < bend) { 363 if (strchr(breakc, tib->tib_data[boff]) && !GETBIT(tib, boff)) { 364 *lastc = tib->tib_data[boff]; 365 return (boff - ti->ti_begin + 1); 366 } 367 boff++; 368 } 369 370 /* Not found - just process the entire block. */ 371 return (bend - ti->ti_begin); 372 } 373 374 void 375 ttyinq_flush(struct ttyinq *ti) 376 { 377 struct ttyinq_block *tib; 378 379 ti->ti_begin = 0; 380 ti->ti_linestart = 0; 381 ti->ti_reprint = 0; 382 ti->ti_end = 0; 383 384 /* Zero all data in the input queue to get rid of passwords. */ 385 if (ttyinq_flush_secure) { 386 for (tib = ti->ti_firstblock; tib != NULL; tib = tib->tib_next) 387 bzero(&tib->tib_data, sizeof tib->tib_data); 388 } 389 } 390 391 int 392 ttyinq_peekchar(struct ttyinq *ti, char *c, int *quote) 393 { 394 unsigned int boff; 395 struct ttyinq_block *tib = ti->ti_lastblock; 396 397 if (ti->ti_linestart == ti->ti_end) 398 return (-1); 399 400 MPASS(ti->ti_end > 0); 401 boff = (ti->ti_end - 1) % TTYINQ_DATASIZE; 402 403 *c = tib->tib_data[boff]; 404 *quote = GETBIT(tib, boff); 405 406 return (0); 407 } 408 409 void 410 ttyinq_unputchar(struct ttyinq *ti) 411 { 412 413 MPASS(ti->ti_linestart < ti->ti_end); 414 415 if (--ti->ti_end % TTYINQ_DATASIZE == 0) { 416 /* Roll back to the previous block. */ 417 ti->ti_lastblock = ti->ti_lastblock->tib_prev; 418 /* 419 * This can only fail if we are unputchar()'ing the 420 * first character in the queue. 421 */ 422 MPASS((ti->ti_lastblock == NULL) == (ti->ti_end == 0)); 423 } 424 } 425 426 void 427 ttyinq_reprintpos_set(struct ttyinq *ti) 428 { 429 430 ti->ti_reprint = ti->ti_end; 431 ti->ti_reprintblock = ti->ti_lastblock; 432 } 433 434 void 435 ttyinq_reprintpos_reset(struct ttyinq *ti) 436 { 437 438 ti->ti_reprint = ti->ti_linestart; 439 ti->ti_reprintblock = ti->ti_startblock; 440 } 441 442 static void 443 ttyinq_line_iterate(struct ttyinq *ti, 444 ttyinq_line_iterator_t *iterator, void *data, 445 unsigned int offset, struct ttyinq_block *tib) 446 { 447 unsigned int boff; 448 449 /* Use the proper block when we're at the queue head. */ 450 if (offset == 0) 451 tib = ti->ti_firstblock; 452 453 /* Iterate all characters and call the iterator function. */ 454 for (; offset < ti->ti_end; offset++) { 455 boff = offset % TTYINQ_DATASIZE; 456 MPASS(tib != NULL); 457 458 /* Call back the iterator function. */ 459 iterator(data, tib->tib_data[boff], GETBIT(tib, boff)); 460 461 /* Last byte iterated - go to the next block. */ 462 if (boff == TTYINQ_DATASIZE - 1) 463 tib = tib->tib_next; 464 } 465 } 466 467 void 468 ttyinq_line_iterate_from_linestart(struct ttyinq *ti, 469 ttyinq_line_iterator_t *iterator, void *data) 470 { 471 472 ttyinq_line_iterate(ti, iterator, data, 473 ti->ti_linestart, ti->ti_startblock); 474 } 475 476 void 477 ttyinq_line_iterate_from_reprintpos(struct ttyinq *ti, 478 ttyinq_line_iterator_t *iterator, void *data) 479 { 480 481 ttyinq_line_iterate(ti, iterator, data, 482 ti->ti_reprint, ti->ti_reprintblock); 483 } 484 485 static void 486 ttyinq_startup(void *dummy) 487 { 488 489 ttyinq_zone = uma_zcreate("ttyinq", sizeof(struct ttyinq_block), 490 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 491 } 492 493 SYSINIT(ttyinq, SI_SUB_DRIVERS, SI_ORDER_FIRST, ttyinq_startup, NULL); 494