1 /*-
2 * SPDX-License-Identifier: BSD-4-Clause
3 *
4 * Copyright (c) 1996 John S. Dyson
5 * Copyright (c) 2012 Giovanni Trematerra
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice immediately at the beginning of the file, without modification,
13 * this list of conditions, and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 3. Absolutely no warranty of function or purpose is made by the author
18 * John S. Dyson.
19 * 4. Modifications may be freely made to this file if the above conditions
20 * are met.
21 */
22
23 /*
24 * This file contains a high-performance replacement for the socket-based
25 * pipes scheme originally used in FreeBSD/4.4Lite. It does not support
26 * all features of sockets, but does do everything that pipes normally
27 * do.
28 */
29
30 /*
31 * This code has two modes of operation, a small write mode and a large
32 * write mode. The small write mode acts like conventional pipes with
33 * a kernel buffer. If the buffer is less than PIPE_MINDIRECT, then the
34 * "normal" pipe buffering is done. If the buffer is between PIPE_MINDIRECT
35 * and PIPE_SIZE in size, the sending process pins the underlying pages in
36 * memory, and the receiving process copies directly from these pinned pages
37 * in the sending process.
38 *
39 * If the sending process receives a signal, it is possible that it will
40 * go away, and certainly its address space can change, because control
41 * is returned back to the user-mode side. In that case, the pipe code
42 * arranges to copy the buffer supplied by the user process, to a pageable
43 * kernel buffer, and the receiving process will grab the data from the
44 * pageable kernel buffer. Since signals don't happen all that often,
45 * the copy operation is normally eliminated.
46 *
47 * The constant PIPE_MINDIRECT is chosen to make sure that buffering will
48 * happen for small transfers so that the system will not spend all of
49 * its time context switching.
50 *
51 * In order to limit the resource use of pipes, two sysctls exist:
52 *
53 * kern.ipc.maxpipekva - This is a hard limit on the amount of pageable
54 * address space available to us in pipe_map. This value is normally
55 * autotuned, but may also be loader tuned.
56 *
57 * kern.ipc.pipekva - This read-only sysctl tracks the current amount of
58 * memory in use by pipes.
59 *
60 * Based on how large pipekva is relative to maxpipekva, the following
61 * will happen:
62 *
63 * 0% - 50%:
64 * New pipes are given 16K of memory backing, pipes may dynamically
65 * grow to as large as 64K where needed.
66 * 50% - 75%:
67 * New pipes are given 4K (or PAGE_SIZE) of memory backing,
68 * existing pipes may NOT grow.
69 * 75% - 100%:
70 * New pipes are given 4K (or PAGE_SIZE) of memory backing,
71 * existing pipes will be shrunk down to 4K whenever possible.
72 *
73 * Resizing may be disabled by setting kern.ipc.piperesizeallowed=0. If
74 * that is set, the only resize that will occur is the 0 -> SMALL_PIPE_SIZE
75 * resize which MUST occur for reverse-direction pipes when they are
76 * first used.
77 *
78 * Additional information about the current state of pipes may be obtained
79 * from kern.ipc.pipes, kern.ipc.pipefragretry, kern.ipc.pipeallocfail,
80 * and kern.ipc.piperesizefail.
81 *
82 * Locking rules: There are two locks present here: A mutex, used via
83 * PIPE_LOCK, and a flag, used via pipelock(). All locking is done via
84 * the flag, as mutexes can not persist over uiomove. The mutex
85 * exists only to guard access to the flag, and is not in itself a
86 * locking mechanism. Also note that there is only a single mutex for
87 * both directions of a pipe.
88 *
89 * As pipelock() may have to sleep before it can acquire the flag, it
90 * is important to reread all data after a call to pipelock(); everything
91 * in the structure may have changed.
92 */
93
94 #include <sys/cdefs.h>
95 __FBSDID("$FreeBSD$");
96
97 #include <sys/param.h>
98 #include <sys/systm.h>
99 #include <sys/conf.h>
100 #include <sys/fcntl.h>
101 #include <sys/file.h>
102 #include <sys/filedesc.h>
103 #include <sys/filio.h>
104 #include <sys/kernel.h>
105 #include <sys/lock.h>
106 #include <sys/mutex.h>
107 #include <sys/ttycom.h>
108 #include <sys/stat.h>
109 #include <sys/malloc.h>
110 #include <sys/poll.h>
111 #include <sys/selinfo.h>
112 #include <sys/signalvar.h>
113 #include <sys/syscallsubr.h>
114 #include <sys/sysctl.h>
115 #include <sys/sysproto.h>
116 #include <sys/pipe.h>
117 #include <sys/proc.h>
118 #include <sys/vnode.h>
119 #include <sys/uio.h>
120 #include <sys/user.h>
121 #include <sys/event.h>
122
123 #include <security/mac/mac_framework.h>
124
125 #include <vm/vm.h>
126 #include <vm/vm_param.h>
127 #include <vm/vm_object.h>
128 #include <vm/vm_kern.h>
129 #include <vm/vm_extern.h>
130 #include <vm/pmap.h>
131 #include <vm/vm_map.h>
132 #include <vm/vm_page.h>
133 #include <vm/uma.h>
134
135 /*
136 * Use this define if you want to disable *fancy* VM things. Expect an
137 * approx 30% decrease in transfer rate. This could be useful for
138 * NetBSD or OpenBSD.
139 */
140 /* #define PIPE_NODIRECT */
141
142 #define PIPE_PEER(pipe) \
143 (((pipe)->pipe_state & PIPE_NAMED) ? (pipe) : ((pipe)->pipe_peer))
144
145 /*
146 * interfaces to the outside world
147 */
148 static fo_rdwr_t pipe_read;
149 static fo_rdwr_t pipe_write;
150 static fo_truncate_t pipe_truncate;
151 static fo_ioctl_t pipe_ioctl;
152 static fo_poll_t pipe_poll;
153 static fo_kqfilter_t pipe_kqfilter;
154 static fo_stat_t pipe_stat;
155 static fo_close_t pipe_close;
156 static fo_chmod_t pipe_chmod;
157 static fo_chown_t pipe_chown;
158 static fo_fill_kinfo_t pipe_fill_kinfo;
159
160 struct fileops pipeops = {
161 .fo_read = pipe_read,
162 .fo_write = pipe_write,
163 .fo_truncate = pipe_truncate,
164 .fo_ioctl = pipe_ioctl,
165 .fo_poll = pipe_poll,
166 .fo_kqfilter = pipe_kqfilter,
167 .fo_stat = pipe_stat,
168 .fo_close = pipe_close,
169 .fo_chmod = pipe_chmod,
170 .fo_chown = pipe_chown,
171 .fo_sendfile = invfo_sendfile,
172 .fo_fill_kinfo = pipe_fill_kinfo,
173 .fo_flags = DFLAG_PASSABLE
174 };
175
176 static void filt_pipedetach(struct knote *kn);
177 static void filt_pipedetach_notsup(struct knote *kn);
178 static int filt_pipenotsup(struct knote *kn, long hint);
179 static int filt_piperead(struct knote *kn, long hint);
180 static int filt_pipewrite(struct knote *kn, long hint);
181
182 static struct filterops pipe_nfiltops = {
183 .f_isfd = 1,
184 .f_detach = filt_pipedetach_notsup,
185 .f_event = filt_pipenotsup
186 };
187 static struct filterops pipe_rfiltops = {
188 .f_isfd = 1,
189 .f_detach = filt_pipedetach,
190 .f_event = filt_piperead
191 };
192 static struct filterops pipe_wfiltops = {
193 .f_isfd = 1,
194 .f_detach = filt_pipedetach,
195 .f_event = filt_pipewrite
196 };
197
198 /*
199 * Default pipe buffer size(s), this can be kind-of large now because pipe
200 * space is pageable. The pipe code will try to maintain locality of
201 * reference for performance reasons, so small amounts of outstanding I/O
202 * will not wipe the cache.
203 */
204 #define MINPIPESIZE (PIPE_SIZE/3)
205 #define MAXPIPESIZE (2*PIPE_SIZE/3)
206
207 static long amountpipekva;
208 static int pipefragretry;
209 static int pipeallocfail;
210 static int piperesizefail;
211 static int piperesizeallowed = 1;
212
213 SYSCTL_LONG(_kern_ipc, OID_AUTO, maxpipekva, CTLFLAG_RDTUN | CTLFLAG_NOFETCH,
214 &maxpipekva, 0, "Pipe KVA limit");
215 SYSCTL_LONG(_kern_ipc, OID_AUTO, pipekva, CTLFLAG_RD,
216 &amountpipekva, 0, "Pipe KVA usage");
217 SYSCTL_INT(_kern_ipc, OID_AUTO, pipefragretry, CTLFLAG_RD,
218 &pipefragretry, 0, "Pipe allocation retries due to fragmentation");
219 SYSCTL_INT(_kern_ipc, OID_AUTO, pipeallocfail, CTLFLAG_RD,
220 &pipeallocfail, 0, "Pipe allocation failures");
221 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizefail, CTLFLAG_RD,
222 &piperesizefail, 0, "Pipe resize failures");
223 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizeallowed, CTLFLAG_RW,
224 &piperesizeallowed, 0, "Pipe resizing allowed");
225
226 static void pipeinit(void *dummy __unused);
227 static void pipeclose(struct pipe *cpipe);
228 static void pipe_free_kmem(struct pipe *cpipe);
229 static void pipe_create(struct pipe *pipe, int backing);
230 static void pipe_paircreate(struct thread *td, struct pipepair **p_pp);
231 static __inline int pipelock(struct pipe *cpipe, int catch);
232 static __inline void pipeunlock(struct pipe *cpipe);
233 #ifndef PIPE_NODIRECT
234 static int pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio);
235 static void pipe_destroy_write_buffer(struct pipe *wpipe);
236 static int pipe_direct_write(struct pipe *wpipe, struct uio *uio);
237 static void pipe_clone_write_buffer(struct pipe *wpipe);
238 #endif
239 static int pipespace(struct pipe *cpipe, int size);
240 static int pipespace_new(struct pipe *cpipe, int size);
241
242 static int pipe_zone_ctor(void *mem, int size, void *arg, int flags);
243 static int pipe_zone_init(void *mem, int size, int flags);
244 static void pipe_zone_fini(void *mem, int size);
245
246 static uma_zone_t pipe_zone;
247 static struct unrhdr64 pipeino_unr;
248 static dev_t pipedev_ino;
249
250 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_ANY, pipeinit, NULL);
251
252 static void
pipeinit(void * dummy __unused)253 pipeinit(void *dummy __unused)
254 {
255
256 pipe_zone = uma_zcreate("pipe", sizeof(struct pipepair),
257 pipe_zone_ctor, NULL, pipe_zone_init, pipe_zone_fini,
258 UMA_ALIGN_PTR, 0);
259 KASSERT(pipe_zone != NULL, ("pipe_zone not initialized"));
260 new_unrhdr64(&pipeino_unr, 1);
261 pipedev_ino = devfs_alloc_cdp_inode();
262 KASSERT(pipedev_ino > 0, ("pipe dev inode not initialized"));
263 }
264
265 static int
pipe_zone_ctor(void * mem,int size,void * arg,int flags)266 pipe_zone_ctor(void *mem, int size, void *arg, int flags)
267 {
268 struct pipepair *pp;
269 struct pipe *rpipe, *wpipe;
270
271 KASSERT(size == sizeof(*pp), ("pipe_zone_ctor: wrong size"));
272
273 pp = (struct pipepair *)mem;
274
275 /*
276 * We zero both pipe endpoints to make sure all the kmem pointers
277 * are NULL, flag fields are zero'd, etc. We timestamp both
278 * endpoints with the same time.
279 */
280 rpipe = &pp->pp_rpipe;
281 bzero(rpipe, sizeof(*rpipe));
282 vfs_timestamp(&rpipe->pipe_ctime);
283 rpipe->pipe_atime = rpipe->pipe_mtime = rpipe->pipe_ctime;
284
285 wpipe = &pp->pp_wpipe;
286 bzero(wpipe, sizeof(*wpipe));
287 wpipe->pipe_ctime = rpipe->pipe_ctime;
288 wpipe->pipe_atime = wpipe->pipe_mtime = rpipe->pipe_ctime;
289
290 rpipe->pipe_peer = wpipe;
291 rpipe->pipe_pair = pp;
292 wpipe->pipe_peer = rpipe;
293 wpipe->pipe_pair = pp;
294
295 /*
296 * Mark both endpoints as present; they will later get free'd
297 * one at a time. When both are free'd, then the whole pair
298 * is released.
299 */
300 rpipe->pipe_present = PIPE_ACTIVE;
301 wpipe->pipe_present = PIPE_ACTIVE;
302
303 /*
304 * Eventually, the MAC Framework may initialize the label
305 * in ctor or init, but for now we do it elswhere to avoid
306 * blocking in ctor or init.
307 */
308 pp->pp_label = NULL;
309
310 return (0);
311 }
312
313 static int
pipe_zone_init(void * mem,int size,int flags)314 pipe_zone_init(void *mem, int size, int flags)
315 {
316 struct pipepair *pp;
317
318 KASSERT(size == sizeof(*pp), ("pipe_zone_init: wrong size"));
319
320 pp = (struct pipepair *)mem;
321
322 mtx_init(&pp->pp_mtx, "pipe mutex", NULL, MTX_DEF | MTX_NEW);
323 return (0);
324 }
325
326 static void
pipe_zone_fini(void * mem,int size)327 pipe_zone_fini(void *mem, int size)
328 {
329 struct pipepair *pp;
330
331 KASSERT(size == sizeof(*pp), ("pipe_zone_fini: wrong size"));
332
333 pp = (struct pipepair *)mem;
334
335 mtx_destroy(&pp->pp_mtx);
336 }
337
338 static void
pipe_paircreate(struct thread * td,struct pipepair ** p_pp)339 pipe_paircreate(struct thread *td, struct pipepair **p_pp)
340 {
341 struct pipepair *pp;
342 struct pipe *rpipe, *wpipe;
343
344 *p_pp = pp = uma_zalloc(pipe_zone, M_WAITOK);
345 #ifdef MAC
346 /*
347 * The MAC label is shared between the connected endpoints. As a
348 * result mac_pipe_init() and mac_pipe_create() are called once
349 * for the pair, and not on the endpoints.
350 */
351 mac_pipe_init(pp);
352 mac_pipe_create(td->td_ucred, pp);
353 #endif
354 rpipe = &pp->pp_rpipe;
355 wpipe = &pp->pp_wpipe;
356
357 knlist_init_mtx(&rpipe->pipe_sel.si_note, PIPE_MTX(rpipe));
358 knlist_init_mtx(&wpipe->pipe_sel.si_note, PIPE_MTX(wpipe));
359
360 /* Only the forward direction pipe is backed by default */
361 pipe_create(rpipe, 1);
362 pipe_create(wpipe, 0);
363
364 rpipe->pipe_state |= PIPE_DIRECTOK;
365 wpipe->pipe_state |= PIPE_DIRECTOK;
366 }
367
368 void
pipe_named_ctor(struct pipe ** ppipe,struct thread * td)369 pipe_named_ctor(struct pipe **ppipe, struct thread *td)
370 {
371 struct pipepair *pp;
372
373 pipe_paircreate(td, &pp);
374 pp->pp_rpipe.pipe_state |= PIPE_NAMED;
375 *ppipe = &pp->pp_rpipe;
376 }
377
378 void
pipe_dtor(struct pipe * dpipe)379 pipe_dtor(struct pipe *dpipe)
380 {
381 struct pipe *peer;
382 ino_t ino;
383
384 ino = dpipe->pipe_ino;
385 peer = (dpipe->pipe_state & PIPE_NAMED) != 0 ? dpipe->pipe_peer : NULL;
386 funsetown(&dpipe->pipe_sigio);
387 pipeclose(dpipe);
388 if (peer != NULL) {
389 funsetown(&peer->pipe_sigio);
390 pipeclose(peer);
391 }
392 }
393
394 /*
395 * The pipe system call for the DTYPE_PIPE type of pipes. If we fail, let
396 * the zone pick up the pieces via pipeclose().
397 */
398 int
kern_pipe(struct thread * td,int fildes[2],int flags,struct filecaps * fcaps1,struct filecaps * fcaps2)399 kern_pipe(struct thread *td, int fildes[2], int flags, struct filecaps *fcaps1,
400 struct filecaps *fcaps2)
401 {
402 struct file *rf, *wf;
403 struct pipe *rpipe, *wpipe;
404 struct pipepair *pp;
405 int fd, fflags, error;
406
407 pipe_paircreate(td, &pp);
408 rpipe = &pp->pp_rpipe;
409 wpipe = &pp->pp_wpipe;
410 error = falloc_caps(td, &rf, &fd, flags, fcaps1);
411 if (error) {
412 pipeclose(rpipe);
413 pipeclose(wpipe);
414 return (error);
415 }
416 /* An extra reference on `rf' has been held for us by falloc_caps(). */
417 fildes[0] = fd;
418
419 fflags = FREAD | FWRITE;
420 if ((flags & O_NONBLOCK) != 0)
421 fflags |= FNONBLOCK;
422
423 /*
424 * Warning: once we've gotten past allocation of the fd for the
425 * read-side, we can only drop the read side via fdrop() in order
426 * to avoid races against processes which manage to dup() the read
427 * side while we are blocked trying to allocate the write side.
428 */
429 finit(rf, fflags, DTYPE_PIPE, rpipe, &pipeops);
430 error = falloc_caps(td, &wf, &fd, flags, fcaps2);
431 if (error) {
432 fdclose(td, rf, fildes[0]);
433 fdrop(rf, td);
434 /* rpipe has been closed by fdrop(). */
435 pipeclose(wpipe);
436 return (error);
437 }
438 /* An extra reference on `wf' has been held for us by falloc_caps(). */
439 finit(wf, fflags, DTYPE_PIPE, wpipe, &pipeops);
440 fdrop(wf, td);
441 fildes[1] = fd;
442 fdrop(rf, td);
443
444 return (0);
445 }
446
447 #ifdef COMPAT_FREEBSD10
448 /* ARGSUSED */
449 int
freebsd10_pipe(struct thread * td,struct freebsd10_pipe_args * uap __unused)450 freebsd10_pipe(struct thread *td, struct freebsd10_pipe_args *uap __unused)
451 {
452 int error;
453 int fildes[2];
454
455 error = kern_pipe(td, fildes, 0, NULL, NULL);
456 if (error)
457 return (error);
458
459 td->td_retval[0] = fildes[0];
460 td->td_retval[1] = fildes[1];
461
462 return (0);
463 }
464 #endif
465
466 int
sys_pipe2(struct thread * td,struct pipe2_args * uap)467 sys_pipe2(struct thread *td, struct pipe2_args *uap)
468 {
469 int error, fildes[2];
470
471 if (uap->flags & ~(O_CLOEXEC | O_NONBLOCK))
472 return (EINVAL);
473 error = kern_pipe(td, fildes, uap->flags, NULL, NULL);
474 if (error)
475 return (error);
476 error = copyout(fildes, uap->fildes, 2 * sizeof(int));
477 if (error) {
478 (void)kern_close(td, fildes[0]);
479 (void)kern_close(td, fildes[1]);
480 }
481 return (error);
482 }
483
484 /*
485 * Allocate kva for pipe circular buffer, the space is pageable
486 * This routine will 'realloc' the size of a pipe safely, if it fails
487 * it will retain the old buffer.
488 * If it fails it will return ENOMEM.
489 */
490 static int
pipespace_new(struct pipe * cpipe,int size)491 pipespace_new(struct pipe *cpipe, int size)
492 {
493 caddr_t buffer;
494 int error, cnt, firstseg;
495 static int curfail = 0;
496 static struct timeval lastfail;
497
498 KASSERT(!mtx_owned(PIPE_MTX(cpipe)), ("pipespace: pipe mutex locked"));
499 KASSERT(!(cpipe->pipe_state & PIPE_DIRECTW),
500 ("pipespace: resize of direct writes not allowed"));
501 retry:
502 cnt = cpipe->pipe_buffer.cnt;
503 if (cnt > size)
504 size = cnt;
505
506 size = round_page(size);
507 buffer = (caddr_t) vm_map_min(pipe_map);
508
509 error = vm_map_find(pipe_map, NULL, 0, (vm_offset_t *)&buffer, size, 0,
510 VMFS_ANY_SPACE, VM_PROT_RW, VM_PROT_RW, 0);
511 if (error != KERN_SUCCESS) {
512 if ((cpipe->pipe_buffer.buffer == NULL) &&
513 (size > SMALL_PIPE_SIZE)) {
514 size = SMALL_PIPE_SIZE;
515 pipefragretry++;
516 goto retry;
517 }
518 if (cpipe->pipe_buffer.buffer == NULL) {
519 pipeallocfail++;
520 if (ppsratecheck(&lastfail, &curfail, 1))
521 printf("kern.ipc.maxpipekva exceeded; see tuning(7)\n");
522 } else {
523 piperesizefail++;
524 }
525 return (ENOMEM);
526 }
527
528 /* copy data, then free old resources if we're resizing */
529 if (cnt > 0) {
530 if (cpipe->pipe_buffer.in <= cpipe->pipe_buffer.out) {
531 firstseg = cpipe->pipe_buffer.size - cpipe->pipe_buffer.out;
532 bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out],
533 buffer, firstseg);
534 if ((cnt - firstseg) > 0)
535 bcopy(cpipe->pipe_buffer.buffer, &buffer[firstseg],
536 cpipe->pipe_buffer.in);
537 } else {
538 bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out],
539 buffer, cnt);
540 }
541 }
542 pipe_free_kmem(cpipe);
543 cpipe->pipe_buffer.buffer = buffer;
544 cpipe->pipe_buffer.size = size;
545 cpipe->pipe_buffer.in = cnt;
546 cpipe->pipe_buffer.out = 0;
547 cpipe->pipe_buffer.cnt = cnt;
548 atomic_add_long(&amountpipekva, cpipe->pipe_buffer.size);
549 return (0);
550 }
551
552 /*
553 * Wrapper for pipespace_new() that performs locking assertions.
554 */
555 static int
pipespace(struct pipe * cpipe,int size)556 pipespace(struct pipe *cpipe, int size)
557 {
558
559 KASSERT(cpipe->pipe_state & PIPE_LOCKFL,
560 ("Unlocked pipe passed to pipespace"));
561 return (pipespace_new(cpipe, size));
562 }
563
564 /*
565 * lock a pipe for I/O, blocking other access
566 */
567 static __inline int
pipelock(struct pipe * cpipe,int catch)568 pipelock(struct pipe *cpipe, int catch)
569 {
570 int error;
571
572 PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
573 while (cpipe->pipe_state & PIPE_LOCKFL) {
574 cpipe->pipe_state |= PIPE_LWANT;
575 error = msleep(cpipe, PIPE_MTX(cpipe),
576 catch ? (PRIBIO | PCATCH) : PRIBIO,
577 "pipelk", 0);
578 if (error != 0)
579 return (error);
580 }
581 cpipe->pipe_state |= PIPE_LOCKFL;
582 return (0);
583 }
584
585 /*
586 * unlock a pipe I/O lock
587 */
588 static __inline void
pipeunlock(struct pipe * cpipe)589 pipeunlock(struct pipe *cpipe)
590 {
591
592 PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
593 KASSERT(cpipe->pipe_state & PIPE_LOCKFL,
594 ("Unlocked pipe passed to pipeunlock"));
595 cpipe->pipe_state &= ~PIPE_LOCKFL;
596 if (cpipe->pipe_state & PIPE_LWANT) {
597 cpipe->pipe_state &= ~PIPE_LWANT;
598 wakeup(cpipe);
599 }
600 }
601
602 void
pipeselwakeup(struct pipe * cpipe)603 pipeselwakeup(struct pipe *cpipe)
604 {
605
606 PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
607 if (cpipe->pipe_state & PIPE_SEL) {
608 selwakeuppri(&cpipe->pipe_sel, PSOCK);
609 if (!SEL_WAITING(&cpipe->pipe_sel))
610 cpipe->pipe_state &= ~PIPE_SEL;
611 }
612 if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio)
613 pgsigio(&cpipe->pipe_sigio, SIGIO, 0);
614 KNOTE_LOCKED(&cpipe->pipe_sel.si_note, 0);
615 }
616
617 /*
618 * Initialize and allocate VM and memory for pipe. The structure
619 * will start out zero'd from the ctor, so we just manage the kmem.
620 */
621 static void
pipe_create(struct pipe * pipe,int backing)622 pipe_create(struct pipe *pipe, int backing)
623 {
624
625 if (backing) {
626 /*
627 * Note that these functions can fail if pipe map is exhausted
628 * (as a result of too many pipes created), but we ignore the
629 * error as it is not fatal and could be provoked by
630 * unprivileged users. The only consequence is worse performance
631 * with given pipe.
632 */
633 if (amountpipekva > maxpipekva / 2)
634 (void)pipespace_new(pipe, SMALL_PIPE_SIZE);
635 else
636 (void)pipespace_new(pipe, PIPE_SIZE);
637 }
638
639 pipe->pipe_ino = alloc_unr64(&pipeino_unr);
640 }
641
642 /* ARGSUSED */
643 static int
pipe_read(struct file * fp,struct uio * uio,struct ucred * active_cred,int flags,struct thread * td)644 pipe_read(struct file *fp, struct uio *uio, struct ucred *active_cred,
645 int flags, struct thread *td)
646 {
647 struct pipe *rpipe;
648 int error;
649 int nread = 0;
650 int size;
651
652 rpipe = fp->f_data;
653 PIPE_LOCK(rpipe);
654 ++rpipe->pipe_busy;
655 error = pipelock(rpipe, 1);
656 if (error)
657 goto unlocked_error;
658
659 #ifdef MAC
660 error = mac_pipe_check_read(active_cred, rpipe->pipe_pair);
661 if (error)
662 goto locked_error;
663 #endif
664 if (amountpipekva > (3 * maxpipekva) / 4) {
665 if (!(rpipe->pipe_state & PIPE_DIRECTW) &&
666 (rpipe->pipe_buffer.size > SMALL_PIPE_SIZE) &&
667 (rpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) &&
668 (piperesizeallowed == 1)) {
669 PIPE_UNLOCK(rpipe);
670 pipespace(rpipe, SMALL_PIPE_SIZE);
671 PIPE_LOCK(rpipe);
672 }
673 }
674
675 while (uio->uio_resid) {
676 /*
677 * normal pipe buffer receive
678 */
679 if (rpipe->pipe_buffer.cnt > 0) {
680 size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out;
681 if (size > rpipe->pipe_buffer.cnt)
682 size = rpipe->pipe_buffer.cnt;
683 if (size > uio->uio_resid)
684 size = uio->uio_resid;
685
686 PIPE_UNLOCK(rpipe);
687 error = uiomove(
688 &rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out],
689 size, uio);
690 PIPE_LOCK(rpipe);
691 if (error)
692 break;
693
694 rpipe->pipe_buffer.out += size;
695 if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size)
696 rpipe->pipe_buffer.out = 0;
697
698 rpipe->pipe_buffer.cnt -= size;
699
700 /*
701 * If there is no more to read in the pipe, reset
702 * its pointers to the beginning. This improves
703 * cache hit stats.
704 */
705 if (rpipe->pipe_buffer.cnt == 0) {
706 rpipe->pipe_buffer.in = 0;
707 rpipe->pipe_buffer.out = 0;
708 }
709 nread += size;
710 #ifndef PIPE_NODIRECT
711 /*
712 * Direct copy, bypassing a kernel buffer.
713 */
714 } else if ((size = rpipe->pipe_map.cnt) != 0) {
715 if (size > uio->uio_resid)
716 size = (u_int) uio->uio_resid;
717 PIPE_UNLOCK(rpipe);
718 error = uiomove_fromphys(rpipe->pipe_map.ms,
719 rpipe->pipe_map.pos, size, uio);
720 PIPE_LOCK(rpipe);
721 if (error)
722 break;
723 nread += size;
724 rpipe->pipe_map.pos += size;
725 rpipe->pipe_map.cnt -= size;
726 if (rpipe->pipe_map.cnt == 0) {
727 rpipe->pipe_state &= ~PIPE_WANTW;
728 wakeup(rpipe);
729 }
730 #endif
731 } else {
732 /*
733 * detect EOF condition
734 * read returns 0 on EOF, no need to set error
735 */
736 if (rpipe->pipe_state & PIPE_EOF)
737 break;
738
739 /*
740 * If the "write-side" has been blocked, wake it up now.
741 */
742 if (rpipe->pipe_state & PIPE_WANTW) {
743 rpipe->pipe_state &= ~PIPE_WANTW;
744 wakeup(rpipe);
745 }
746
747 /*
748 * Break if some data was read.
749 */
750 if (nread > 0)
751 break;
752
753 /*
754 * Unlock the pipe buffer for our remaining processing.
755 * We will either break out with an error or we will
756 * sleep and relock to loop.
757 */
758 pipeunlock(rpipe);
759
760 /*
761 * Handle non-blocking mode operation or
762 * wait for more data.
763 */
764 if (fp->f_flag & FNONBLOCK) {
765 error = EAGAIN;
766 } else {
767 rpipe->pipe_state |= PIPE_WANTR;
768 if ((error = msleep(rpipe, PIPE_MTX(rpipe),
769 PRIBIO | PCATCH,
770 "piperd", 0)) == 0)
771 error = pipelock(rpipe, 1);
772 }
773 if (error)
774 goto unlocked_error;
775 }
776 }
777 #ifdef MAC
778 locked_error:
779 #endif
780 pipeunlock(rpipe);
781
782 /* XXX: should probably do this before getting any locks. */
783 if (error == 0)
784 vfs_timestamp(&rpipe->pipe_atime);
785 unlocked_error:
786 --rpipe->pipe_busy;
787
788 /*
789 * PIPE_WANT processing only makes sense if pipe_busy is 0.
790 */
791 if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) {
792 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW);
793 wakeup(rpipe);
794 } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) {
795 /*
796 * Handle write blocking hysteresis.
797 */
798 if (rpipe->pipe_state & PIPE_WANTW) {
799 rpipe->pipe_state &= ~PIPE_WANTW;
800 wakeup(rpipe);
801 }
802 }
803
804 if ((rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt) >= PIPE_BUF)
805 pipeselwakeup(rpipe);
806
807 PIPE_UNLOCK(rpipe);
808 return (error);
809 }
810
811 #ifndef PIPE_NODIRECT
812 /*
813 * Map the sending processes' buffer into kernel space and wire it.
814 * This is similar to a physical write operation.
815 */
816 static int
pipe_build_write_buffer(struct pipe * wpipe,struct uio * uio)817 pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio)
818 {
819 u_int size;
820 int i;
821
822 PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
823 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) == 0,
824 ("%s: PIPE_DIRECTW set on %p", __func__, wpipe));
825 KASSERT(wpipe->pipe_map.cnt == 0,
826 ("%s: pipe map for %p contains residual data", __func__, wpipe));
827
828 if (uio->uio_iov->iov_len > wpipe->pipe_buffer.size)
829 size = wpipe->pipe_buffer.size;
830 else
831 size = uio->uio_iov->iov_len;
832
833 wpipe->pipe_state |= PIPE_DIRECTW;
834 PIPE_UNLOCK(wpipe);
835 i = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map,
836 (vm_offset_t)uio->uio_iov->iov_base, size, VM_PROT_READ,
837 wpipe->pipe_map.ms, PIPENPAGES);
838 PIPE_LOCK(wpipe);
839 if (i < 0) {
840 wpipe->pipe_state &= ~PIPE_DIRECTW;
841 return (EFAULT);
842 }
843
844 wpipe->pipe_map.npages = i;
845 wpipe->pipe_map.pos =
846 ((vm_offset_t) uio->uio_iov->iov_base) & PAGE_MASK;
847 wpipe->pipe_map.cnt = size;
848
849 uio->uio_iov->iov_len -= size;
850 uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + size;
851 if (uio->uio_iov->iov_len == 0)
852 uio->uio_iov++;
853 uio->uio_resid -= size;
854 uio->uio_offset += size;
855 return (0);
856 }
857
858 /*
859 * Unwire the process buffer.
860 */
861 static void
pipe_destroy_write_buffer(struct pipe * wpipe)862 pipe_destroy_write_buffer(struct pipe *wpipe)
863 {
864
865 PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
866 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) != 0,
867 ("%s: PIPE_DIRECTW not set on %p", __func__, wpipe));
868 KASSERT(wpipe->pipe_map.cnt == 0,
869 ("%s: pipe map for %p contains residual data", __func__, wpipe));
870
871 wpipe->pipe_state &= ~PIPE_DIRECTW;
872 vm_page_unhold_pages(wpipe->pipe_map.ms, wpipe->pipe_map.npages);
873 wpipe->pipe_map.npages = 0;
874 }
875
876 /*
877 * In the case of a signal, the writing process might go away. This
878 * code copies the data into the circular buffer so that the source
879 * pages can be freed without loss of data.
880 */
881 static void
pipe_clone_write_buffer(struct pipe * wpipe)882 pipe_clone_write_buffer(struct pipe *wpipe)
883 {
884 struct uio uio;
885 struct iovec iov;
886 int size;
887 int pos;
888
889 PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
890 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) != 0,
891 ("%s: PIPE_DIRECTW not set on %p", __func__, wpipe));
892
893 size = wpipe->pipe_map.cnt;
894 pos = wpipe->pipe_map.pos;
895 wpipe->pipe_map.cnt = 0;
896
897 wpipe->pipe_buffer.in = size;
898 wpipe->pipe_buffer.out = 0;
899 wpipe->pipe_buffer.cnt = size;
900
901 PIPE_UNLOCK(wpipe);
902 iov.iov_base = wpipe->pipe_buffer.buffer;
903 iov.iov_len = size;
904 uio.uio_iov = &iov;
905 uio.uio_iovcnt = 1;
906 uio.uio_offset = 0;
907 uio.uio_resid = size;
908 uio.uio_segflg = UIO_SYSSPACE;
909 uio.uio_rw = UIO_READ;
910 uio.uio_td = curthread;
911 uiomove_fromphys(wpipe->pipe_map.ms, pos, size, &uio);
912 PIPE_LOCK(wpipe);
913 pipe_destroy_write_buffer(wpipe);
914 }
915
916 /*
917 * This implements the pipe buffer write mechanism. Note that only
918 * a direct write OR a normal pipe write can be pending at any given time.
919 * If there are any characters in the pipe buffer, the direct write will
920 * be deferred until the receiving process grabs all of the bytes from
921 * the pipe buffer. Then the direct mapping write is set-up.
922 */
923 static int
pipe_direct_write(struct pipe * wpipe,struct uio * uio)924 pipe_direct_write(struct pipe *wpipe, struct uio *uio)
925 {
926 int error;
927
928 retry:
929 PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
930 error = pipelock(wpipe, 1);
931 if (error != 0)
932 goto error1;
933 if ((wpipe->pipe_state & PIPE_EOF) != 0) {
934 error = EPIPE;
935 pipeunlock(wpipe);
936 goto error1;
937 }
938 if (wpipe->pipe_state & PIPE_DIRECTW) {
939 if (wpipe->pipe_state & PIPE_WANTR) {
940 wpipe->pipe_state &= ~PIPE_WANTR;
941 wakeup(wpipe);
942 }
943 pipeselwakeup(wpipe);
944 wpipe->pipe_state |= PIPE_WANTW;
945 pipeunlock(wpipe);
946 error = msleep(wpipe, PIPE_MTX(wpipe),
947 PRIBIO | PCATCH, "pipdww", 0);
948 if (error)
949 goto error1;
950 else
951 goto retry;
952 }
953 if (wpipe->pipe_buffer.cnt > 0) {
954 if (wpipe->pipe_state & PIPE_WANTR) {
955 wpipe->pipe_state &= ~PIPE_WANTR;
956 wakeup(wpipe);
957 }
958 pipeselwakeup(wpipe);
959 wpipe->pipe_state |= PIPE_WANTW;
960 pipeunlock(wpipe);
961 error = msleep(wpipe, PIPE_MTX(wpipe),
962 PRIBIO | PCATCH, "pipdwc", 0);
963 if (error)
964 goto error1;
965 else
966 goto retry;
967 }
968
969 error = pipe_build_write_buffer(wpipe, uio);
970 if (error) {
971 pipeunlock(wpipe);
972 goto error1;
973 }
974
975 while (wpipe->pipe_map.cnt != 0) {
976 if (wpipe->pipe_state & PIPE_EOF) {
977 wpipe->pipe_map.cnt = 0;
978 pipe_destroy_write_buffer(wpipe);
979 pipeselwakeup(wpipe);
980 pipeunlock(wpipe);
981 error = EPIPE;
982 goto error1;
983 }
984 if (wpipe->pipe_state & PIPE_WANTR) {
985 wpipe->pipe_state &= ~PIPE_WANTR;
986 wakeup(wpipe);
987 }
988 pipeselwakeup(wpipe);
989 wpipe->pipe_state |= PIPE_WANTW;
990 pipeunlock(wpipe);
991 error = msleep(wpipe, PIPE_MTX(wpipe), PRIBIO | PCATCH,
992 "pipdwt", 0);
993 pipelock(wpipe, 0);
994 if (error != 0)
995 break;
996 }
997
998 if (wpipe->pipe_state & PIPE_EOF)
999 error = EPIPE;
1000 if (error == EINTR || error == ERESTART)
1001 pipe_clone_write_buffer(wpipe);
1002 else
1003 pipe_destroy_write_buffer(wpipe);
1004 pipeunlock(wpipe);
1005 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) == 0,
1006 ("pipe %p leaked PIPE_DIRECTW", wpipe));
1007 return (error);
1008
1009 error1:
1010 wakeup(wpipe);
1011 return (error);
1012 }
1013 #endif
1014
1015 static int
pipe_write(struct file * fp,struct uio * uio,struct ucred * active_cred,int flags,struct thread * td)1016 pipe_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
1017 int flags, struct thread *td)
1018 {
1019 int error = 0;
1020 int desiredsize;
1021 ssize_t orig_resid;
1022 struct pipe *wpipe, *rpipe;
1023
1024 rpipe = fp->f_data;
1025 wpipe = PIPE_PEER(rpipe);
1026 PIPE_LOCK(rpipe);
1027 error = pipelock(wpipe, 1);
1028 if (error) {
1029 PIPE_UNLOCK(rpipe);
1030 return (error);
1031 }
1032 /*
1033 * detect loss of pipe read side, issue SIGPIPE if lost.
1034 */
1035 if (wpipe->pipe_present != PIPE_ACTIVE ||
1036 (wpipe->pipe_state & PIPE_EOF)) {
1037 pipeunlock(wpipe);
1038 PIPE_UNLOCK(rpipe);
1039 return (EPIPE);
1040 }
1041 #ifdef MAC
1042 error = mac_pipe_check_write(active_cred, wpipe->pipe_pair);
1043 if (error) {
1044 pipeunlock(wpipe);
1045 PIPE_UNLOCK(rpipe);
1046 return (error);
1047 }
1048 #endif
1049 ++wpipe->pipe_busy;
1050
1051 /* Choose a larger size if it's advantageous */
1052 desiredsize = max(SMALL_PIPE_SIZE, wpipe->pipe_buffer.size);
1053 while (desiredsize < wpipe->pipe_buffer.cnt + uio->uio_resid) {
1054 if (piperesizeallowed != 1)
1055 break;
1056 if (amountpipekva > maxpipekva / 2)
1057 break;
1058 if (desiredsize == BIG_PIPE_SIZE)
1059 break;
1060 desiredsize = desiredsize * 2;
1061 }
1062
1063 /* Choose a smaller size if we're in a OOM situation */
1064 if ((amountpipekva > (3 * maxpipekva) / 4) &&
1065 (wpipe->pipe_buffer.size > SMALL_PIPE_SIZE) &&
1066 (wpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) &&
1067 (piperesizeallowed == 1))
1068 desiredsize = SMALL_PIPE_SIZE;
1069
1070 /* Resize if the above determined that a new size was necessary */
1071 if ((desiredsize != wpipe->pipe_buffer.size) &&
1072 ((wpipe->pipe_state & PIPE_DIRECTW) == 0)) {
1073 PIPE_UNLOCK(wpipe);
1074 pipespace(wpipe, desiredsize);
1075 PIPE_LOCK(wpipe);
1076 }
1077 if (wpipe->pipe_buffer.size == 0) {
1078 /*
1079 * This can only happen for reverse direction use of pipes
1080 * in a complete OOM situation.
1081 */
1082 error = ENOMEM;
1083 --wpipe->pipe_busy;
1084 pipeunlock(wpipe);
1085 PIPE_UNLOCK(wpipe);
1086 return (error);
1087 }
1088
1089 pipeunlock(wpipe);
1090
1091 orig_resid = uio->uio_resid;
1092
1093 while (uio->uio_resid) {
1094 int space;
1095
1096 pipelock(wpipe, 0);
1097 if (wpipe->pipe_state & PIPE_EOF) {
1098 pipeunlock(wpipe);
1099 error = EPIPE;
1100 break;
1101 }
1102 #ifndef PIPE_NODIRECT
1103 /*
1104 * If the transfer is large, we can gain performance if
1105 * we do process-to-process copies directly.
1106 * If the write is non-blocking, we don't use the
1107 * direct write mechanism.
1108 *
1109 * The direct write mechanism will detect the reader going
1110 * away on us.
1111 */
1112 if (uio->uio_segflg == UIO_USERSPACE &&
1113 uio->uio_iov->iov_len >= PIPE_MINDIRECT &&
1114 wpipe->pipe_buffer.size >= PIPE_MINDIRECT &&
1115 (fp->f_flag & FNONBLOCK) == 0) {
1116 pipeunlock(wpipe);
1117 error = pipe_direct_write(wpipe, uio);
1118 if (error)
1119 break;
1120 continue;
1121 }
1122 #endif
1123
1124 /*
1125 * Pipe buffered writes cannot be coincidental with
1126 * direct writes. We wait until the currently executing
1127 * direct write is completed before we start filling the
1128 * pipe buffer. We break out if a signal occurs or the
1129 * reader goes away.
1130 */
1131 if (wpipe->pipe_map.cnt != 0) {
1132 if (wpipe->pipe_state & PIPE_WANTR) {
1133 wpipe->pipe_state &= ~PIPE_WANTR;
1134 wakeup(wpipe);
1135 }
1136 pipeselwakeup(wpipe);
1137 wpipe->pipe_state |= PIPE_WANTW;
1138 pipeunlock(wpipe);
1139 error = msleep(wpipe, PIPE_MTX(rpipe), PRIBIO | PCATCH,
1140 "pipbww", 0);
1141 if (error)
1142 break;
1143 else
1144 continue;
1145 }
1146
1147 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
1148
1149 /* Writes of size <= PIPE_BUF must be atomic. */
1150 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF))
1151 space = 0;
1152
1153 if (space > 0) {
1154 int size; /* Transfer size */
1155 int segsize; /* first segment to transfer */
1156
1157 /*
1158 * Transfer size is minimum of uio transfer
1159 * and free space in pipe buffer.
1160 */
1161 if (space > uio->uio_resid)
1162 size = uio->uio_resid;
1163 else
1164 size = space;
1165 /*
1166 * First segment to transfer is minimum of
1167 * transfer size and contiguous space in
1168 * pipe buffer. If first segment to transfer
1169 * is less than the transfer size, we've got
1170 * a wraparound in the buffer.
1171 */
1172 segsize = wpipe->pipe_buffer.size -
1173 wpipe->pipe_buffer.in;
1174 if (segsize > size)
1175 segsize = size;
1176
1177 /* Transfer first segment */
1178
1179 PIPE_UNLOCK(rpipe);
1180 error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in],
1181 segsize, uio);
1182 PIPE_LOCK(rpipe);
1183
1184 if (error == 0 && segsize < size) {
1185 KASSERT(wpipe->pipe_buffer.in + segsize ==
1186 wpipe->pipe_buffer.size,
1187 ("Pipe buffer wraparound disappeared"));
1188 /*
1189 * Transfer remaining part now, to
1190 * support atomic writes. Wraparound
1191 * happened.
1192 */
1193
1194 PIPE_UNLOCK(rpipe);
1195 error = uiomove(
1196 &wpipe->pipe_buffer.buffer[0],
1197 size - segsize, uio);
1198 PIPE_LOCK(rpipe);
1199 }
1200 if (error == 0) {
1201 wpipe->pipe_buffer.in += size;
1202 if (wpipe->pipe_buffer.in >=
1203 wpipe->pipe_buffer.size) {
1204 KASSERT(wpipe->pipe_buffer.in ==
1205 size - segsize +
1206 wpipe->pipe_buffer.size,
1207 ("Expected wraparound bad"));
1208 wpipe->pipe_buffer.in = size - segsize;
1209 }
1210
1211 wpipe->pipe_buffer.cnt += size;
1212 KASSERT(wpipe->pipe_buffer.cnt <=
1213 wpipe->pipe_buffer.size,
1214 ("Pipe buffer overflow"));
1215 }
1216 pipeunlock(wpipe);
1217 if (error != 0)
1218 break;
1219 } else {
1220 /*
1221 * If the "read-side" has been blocked, wake it up now.
1222 */
1223 if (wpipe->pipe_state & PIPE_WANTR) {
1224 wpipe->pipe_state &= ~PIPE_WANTR;
1225 wakeup(wpipe);
1226 }
1227
1228 /*
1229 * don't block on non-blocking I/O
1230 */
1231 if (fp->f_flag & FNONBLOCK) {
1232 error = EAGAIN;
1233 pipeunlock(wpipe);
1234 break;
1235 }
1236
1237 /*
1238 * We have no more space and have something to offer,
1239 * wake up select/poll.
1240 */
1241 pipeselwakeup(wpipe);
1242
1243 wpipe->pipe_state |= PIPE_WANTW;
1244 pipeunlock(wpipe);
1245 error = msleep(wpipe, PIPE_MTX(rpipe),
1246 PRIBIO | PCATCH, "pipewr", 0);
1247 if (error != 0)
1248 break;
1249 }
1250 }
1251
1252 pipelock(wpipe, 0);
1253 --wpipe->pipe_busy;
1254
1255 if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) {
1256 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR);
1257 wakeup(wpipe);
1258 } else if (wpipe->pipe_buffer.cnt > 0) {
1259 /*
1260 * If we have put any characters in the buffer, we wake up
1261 * the reader.
1262 */
1263 if (wpipe->pipe_state & PIPE_WANTR) {
1264 wpipe->pipe_state &= ~PIPE_WANTR;
1265 wakeup(wpipe);
1266 }
1267 }
1268
1269 /*
1270 * Don't return EPIPE if any byte was written.
1271 * EINTR and other interrupts are handled by generic I/O layer.
1272 * Do not pretend that I/O succeeded for obvious user error
1273 * like EFAULT.
1274 */
1275 if (uio->uio_resid != orig_resid && error == EPIPE)
1276 error = 0;
1277
1278 if (error == 0)
1279 vfs_timestamp(&wpipe->pipe_mtime);
1280
1281 /*
1282 * We have something to offer,
1283 * wake up select/poll.
1284 */
1285 if (wpipe->pipe_buffer.cnt)
1286 pipeselwakeup(wpipe);
1287
1288 pipeunlock(wpipe);
1289 PIPE_UNLOCK(rpipe);
1290 return (error);
1291 }
1292
1293 /* ARGSUSED */
1294 static int
pipe_truncate(struct file * fp,off_t length,struct ucred * active_cred,struct thread * td)1295 pipe_truncate(struct file *fp, off_t length, struct ucred *active_cred,
1296 struct thread *td)
1297 {
1298 struct pipe *cpipe;
1299 int error;
1300
1301 cpipe = fp->f_data;
1302 if (cpipe->pipe_state & PIPE_NAMED)
1303 error = vnops.fo_truncate(fp, length, active_cred, td);
1304 else
1305 error = invfo_truncate(fp, length, active_cred, td);
1306 return (error);
1307 }
1308
1309 /*
1310 * we implement a very minimal set of ioctls for compatibility with sockets.
1311 */
1312 static int
pipe_ioctl(struct file * fp,u_long cmd,void * data,struct ucred * active_cred,struct thread * td)1313 pipe_ioctl(struct file *fp, u_long cmd, void *data, struct ucred *active_cred,
1314 struct thread *td)
1315 {
1316 struct pipe *mpipe = fp->f_data;
1317 int error;
1318
1319 PIPE_LOCK(mpipe);
1320
1321 #ifdef MAC
1322 error = mac_pipe_check_ioctl(active_cred, mpipe->pipe_pair, cmd, data);
1323 if (error) {
1324 PIPE_UNLOCK(mpipe);
1325 return (error);
1326 }
1327 #endif
1328
1329 error = 0;
1330 switch (cmd) {
1331
1332 case FIONBIO:
1333 break;
1334
1335 case FIOASYNC:
1336 if (*(int *)data) {
1337 mpipe->pipe_state |= PIPE_ASYNC;
1338 } else {
1339 mpipe->pipe_state &= ~PIPE_ASYNC;
1340 }
1341 break;
1342
1343 case FIONREAD:
1344 if (!(fp->f_flag & FREAD)) {
1345 *(int *)data = 0;
1346 PIPE_UNLOCK(mpipe);
1347 return (0);
1348 }
1349 if (mpipe->pipe_map.cnt != 0)
1350 *(int *)data = mpipe->pipe_map.cnt;
1351 else
1352 *(int *)data = mpipe->pipe_buffer.cnt;
1353 break;
1354
1355 case FIOSETOWN:
1356 PIPE_UNLOCK(mpipe);
1357 error = fsetown(*(int *)data, &mpipe->pipe_sigio);
1358 goto out_unlocked;
1359
1360 case FIOGETOWN:
1361 *(int *)data = fgetown(&mpipe->pipe_sigio);
1362 break;
1363
1364 /* This is deprecated, FIOSETOWN should be used instead. */
1365 case TIOCSPGRP:
1366 PIPE_UNLOCK(mpipe);
1367 error = fsetown(-(*(int *)data), &mpipe->pipe_sigio);
1368 goto out_unlocked;
1369
1370 /* This is deprecated, FIOGETOWN should be used instead. */
1371 case TIOCGPGRP:
1372 *(int *)data = -fgetown(&mpipe->pipe_sigio);
1373 break;
1374
1375 default:
1376 error = ENOTTY;
1377 break;
1378 }
1379 PIPE_UNLOCK(mpipe);
1380 out_unlocked:
1381 return (error);
1382 }
1383
1384 static int
pipe_poll(struct file * fp,int events,struct ucred * active_cred,struct thread * td)1385 pipe_poll(struct file *fp, int events, struct ucred *active_cred,
1386 struct thread *td)
1387 {
1388 struct pipe *rpipe;
1389 struct pipe *wpipe;
1390 int levents, revents;
1391 #ifdef MAC
1392 int error;
1393 #endif
1394
1395 revents = 0;
1396 rpipe = fp->f_data;
1397 wpipe = PIPE_PEER(rpipe);
1398 PIPE_LOCK(rpipe);
1399 #ifdef MAC
1400 error = mac_pipe_check_poll(active_cred, rpipe->pipe_pair);
1401 if (error)
1402 goto locked_error;
1403 #endif
1404 if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM))
1405 if (rpipe->pipe_map.cnt > 0 || rpipe->pipe_buffer.cnt > 0)
1406 revents |= events & (POLLIN | POLLRDNORM);
1407
1408 if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM))
1409 if (wpipe->pipe_present != PIPE_ACTIVE ||
1410 (wpipe->pipe_state & PIPE_EOF) ||
1411 ((wpipe->pipe_state & PIPE_DIRECTW) == 0 &&
1412 ((wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF ||
1413 wpipe->pipe_buffer.size == 0)))
1414 revents |= events & (POLLOUT | POLLWRNORM);
1415
1416 levents = events &
1417 (POLLIN | POLLINIGNEOF | POLLPRI | POLLRDNORM | POLLRDBAND);
1418 if (rpipe->pipe_state & PIPE_NAMED && fp->f_flag & FREAD && levents &&
1419 fp->f_pipegen == rpipe->pipe_wgen)
1420 events |= POLLINIGNEOF;
1421
1422 if ((events & POLLINIGNEOF) == 0) {
1423 if (rpipe->pipe_state & PIPE_EOF) {
1424 revents |= (events & (POLLIN | POLLRDNORM));
1425 if (wpipe->pipe_present != PIPE_ACTIVE ||
1426 (wpipe->pipe_state & PIPE_EOF))
1427 revents |= POLLHUP;
1428 }
1429 }
1430
1431 if (revents == 0) {
1432 if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM)) {
1433 selrecord(td, &rpipe->pipe_sel);
1434 if (SEL_WAITING(&rpipe->pipe_sel))
1435 rpipe->pipe_state |= PIPE_SEL;
1436 }
1437
1438 if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM)) {
1439 selrecord(td, &wpipe->pipe_sel);
1440 if (SEL_WAITING(&wpipe->pipe_sel))
1441 wpipe->pipe_state |= PIPE_SEL;
1442 }
1443 }
1444 #ifdef MAC
1445 locked_error:
1446 #endif
1447 PIPE_UNLOCK(rpipe);
1448
1449 return (revents);
1450 }
1451
1452 /*
1453 * We shouldn't need locks here as we're doing a read and this should
1454 * be a natural race.
1455 */
1456 static int
pipe_stat(struct file * fp,struct stat * ub,struct ucred * active_cred,struct thread * td)1457 pipe_stat(struct file *fp, struct stat *ub, struct ucred *active_cred,
1458 struct thread *td)
1459 {
1460 struct pipe *pipe;
1461 #ifdef MAC
1462 int error;
1463 #endif
1464
1465 pipe = fp->f_data;
1466 PIPE_LOCK(pipe);
1467 #ifdef MAC
1468 error = mac_pipe_check_stat(active_cred, pipe->pipe_pair);
1469 if (error) {
1470 PIPE_UNLOCK(pipe);
1471 return (error);
1472 }
1473 #endif
1474
1475 /* For named pipes ask the underlying filesystem. */
1476 if (pipe->pipe_state & PIPE_NAMED) {
1477 PIPE_UNLOCK(pipe);
1478 return (vnops.fo_stat(fp, ub, active_cred, td));
1479 }
1480
1481 PIPE_UNLOCK(pipe);
1482
1483 bzero(ub, sizeof(*ub));
1484 ub->st_mode = S_IFIFO;
1485 ub->st_blksize = PAGE_SIZE;
1486 if (pipe->pipe_map.cnt != 0)
1487 ub->st_size = pipe->pipe_map.cnt;
1488 else
1489 ub->st_size = pipe->pipe_buffer.cnt;
1490 ub->st_blocks = howmany(ub->st_size, ub->st_blksize);
1491 ub->st_atim = pipe->pipe_atime;
1492 ub->st_mtim = pipe->pipe_mtime;
1493 ub->st_ctim = pipe->pipe_ctime;
1494 ub->st_uid = fp->f_cred->cr_uid;
1495 ub->st_gid = fp->f_cred->cr_gid;
1496 ub->st_dev = pipedev_ino;
1497 ub->st_ino = pipe->pipe_ino;
1498 /*
1499 * Left as 0: st_nlink, st_rdev, st_flags, st_gen.
1500 */
1501 return (0);
1502 }
1503
1504 /* ARGSUSED */
1505 static int
pipe_close(struct file * fp,struct thread * td)1506 pipe_close(struct file *fp, struct thread *td)
1507 {
1508
1509 if (fp->f_vnode != NULL)
1510 return vnops.fo_close(fp, td);
1511 fp->f_ops = &badfileops;
1512 pipe_dtor(fp->f_data);
1513 fp->f_data = NULL;
1514 return (0);
1515 }
1516
1517 static int
pipe_chmod(struct file * fp,mode_t mode,struct ucred * active_cred,struct thread * td)1518 pipe_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, struct thread *td)
1519 {
1520 struct pipe *cpipe;
1521 int error;
1522
1523 cpipe = fp->f_data;
1524 if (cpipe->pipe_state & PIPE_NAMED)
1525 error = vn_chmod(fp, mode, active_cred, td);
1526 else
1527 error = invfo_chmod(fp, mode, active_cred, td);
1528 return (error);
1529 }
1530
1531 static int
pipe_chown(struct file * fp,uid_t uid,gid_t gid,struct ucred * active_cred,struct thread * td)1532 pipe_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred,
1533 struct thread *td)
1534 {
1535 struct pipe *cpipe;
1536 int error;
1537
1538 cpipe = fp->f_data;
1539 if (cpipe->pipe_state & PIPE_NAMED)
1540 error = vn_chown(fp, uid, gid, active_cred, td);
1541 else
1542 error = invfo_chown(fp, uid, gid, active_cred, td);
1543 return (error);
1544 }
1545
1546 static int
pipe_fill_kinfo(struct file * fp,struct kinfo_file * kif,struct filedesc * fdp)1547 pipe_fill_kinfo(struct file *fp, struct kinfo_file *kif, struct filedesc *fdp)
1548 {
1549 struct pipe *pi;
1550
1551 if (fp->f_type == DTYPE_FIFO)
1552 return (vn_fill_kinfo(fp, kif, fdp));
1553 kif->kf_type = KF_TYPE_PIPE;
1554 pi = fp->f_data;
1555 kif->kf_un.kf_pipe.kf_pipe_addr = (uintptr_t)pi;
1556 kif->kf_un.kf_pipe.kf_pipe_peer = (uintptr_t)pi->pipe_peer;
1557 kif->kf_un.kf_pipe.kf_pipe_buffer_cnt = pi->pipe_buffer.cnt;
1558 return (0);
1559 }
1560
1561 static void
pipe_free_kmem(struct pipe * cpipe)1562 pipe_free_kmem(struct pipe *cpipe)
1563 {
1564
1565 KASSERT(!mtx_owned(PIPE_MTX(cpipe)),
1566 ("pipe_free_kmem: pipe mutex locked"));
1567
1568 if (cpipe->pipe_buffer.buffer != NULL) {
1569 atomic_subtract_long(&amountpipekva, cpipe->pipe_buffer.size);
1570 vm_map_remove(pipe_map,
1571 (vm_offset_t)cpipe->pipe_buffer.buffer,
1572 (vm_offset_t)cpipe->pipe_buffer.buffer + cpipe->pipe_buffer.size);
1573 cpipe->pipe_buffer.buffer = NULL;
1574 }
1575 #ifndef PIPE_NODIRECT
1576 {
1577 cpipe->pipe_map.cnt = 0;
1578 cpipe->pipe_map.pos = 0;
1579 cpipe->pipe_map.npages = 0;
1580 }
1581 #endif
1582 }
1583
1584 /*
1585 * shutdown the pipe
1586 */
1587 static void
pipeclose(struct pipe * cpipe)1588 pipeclose(struct pipe *cpipe)
1589 {
1590 struct pipepair *pp;
1591 struct pipe *ppipe;
1592
1593 KASSERT(cpipe != NULL, ("pipeclose: cpipe == NULL"));
1594
1595 PIPE_LOCK(cpipe);
1596 pipelock(cpipe, 0);
1597 pp = cpipe->pipe_pair;
1598
1599 pipeselwakeup(cpipe);
1600
1601 /*
1602 * If the other side is blocked, wake it up saying that
1603 * we want to close it down.
1604 */
1605 cpipe->pipe_state |= PIPE_EOF;
1606 while (cpipe->pipe_busy) {
1607 wakeup(cpipe);
1608 cpipe->pipe_state |= PIPE_WANT;
1609 pipeunlock(cpipe);
1610 msleep(cpipe, PIPE_MTX(cpipe), PRIBIO, "pipecl", 0);
1611 pipelock(cpipe, 0);
1612 }
1613
1614
1615 /*
1616 * Disconnect from peer, if any.
1617 */
1618 ppipe = cpipe->pipe_peer;
1619 if (ppipe->pipe_present == PIPE_ACTIVE) {
1620 pipeselwakeup(ppipe);
1621
1622 ppipe->pipe_state |= PIPE_EOF;
1623 wakeup(ppipe);
1624 KNOTE_LOCKED(&ppipe->pipe_sel.si_note, 0);
1625 }
1626
1627 /*
1628 * Mark this endpoint as free. Release kmem resources. We
1629 * don't mark this endpoint as unused until we've finished
1630 * doing that, or the pipe might disappear out from under
1631 * us.
1632 */
1633 PIPE_UNLOCK(cpipe);
1634 pipe_free_kmem(cpipe);
1635 PIPE_LOCK(cpipe);
1636 cpipe->pipe_present = PIPE_CLOSING;
1637 pipeunlock(cpipe);
1638
1639 /*
1640 * knlist_clear() may sleep dropping the PIPE_MTX. Set the
1641 * PIPE_FINALIZED, that allows other end to free the
1642 * pipe_pair, only after the knotes are completely dismantled.
1643 */
1644 knlist_clear(&cpipe->pipe_sel.si_note, 1);
1645 cpipe->pipe_present = PIPE_FINALIZED;
1646 seldrain(&cpipe->pipe_sel);
1647 knlist_destroy(&cpipe->pipe_sel.si_note);
1648
1649 /*
1650 * If both endpoints are now closed, release the memory for the
1651 * pipe pair. If not, unlock.
1652 */
1653 if (ppipe->pipe_present == PIPE_FINALIZED) {
1654 PIPE_UNLOCK(cpipe);
1655 #ifdef MAC
1656 mac_pipe_destroy(pp);
1657 #endif
1658 uma_zfree(pipe_zone, cpipe->pipe_pair);
1659 } else
1660 PIPE_UNLOCK(cpipe);
1661 }
1662
1663 /*ARGSUSED*/
1664 static int
pipe_kqfilter(struct file * fp,struct knote * kn)1665 pipe_kqfilter(struct file *fp, struct knote *kn)
1666 {
1667 struct pipe *cpipe;
1668
1669 /*
1670 * If a filter is requested that is not supported by this file
1671 * descriptor, don't return an error, but also don't ever generate an
1672 * event.
1673 */
1674 if ((kn->kn_filter == EVFILT_READ) && !(fp->f_flag & FREAD)) {
1675 kn->kn_fop = &pipe_nfiltops;
1676 return (0);
1677 }
1678 if ((kn->kn_filter == EVFILT_WRITE) && !(fp->f_flag & FWRITE)) {
1679 kn->kn_fop = &pipe_nfiltops;
1680 return (0);
1681 }
1682 cpipe = fp->f_data;
1683 PIPE_LOCK(cpipe);
1684 switch (kn->kn_filter) {
1685 case EVFILT_READ:
1686 kn->kn_fop = &pipe_rfiltops;
1687 break;
1688 case EVFILT_WRITE:
1689 kn->kn_fop = &pipe_wfiltops;
1690 if (cpipe->pipe_peer->pipe_present != PIPE_ACTIVE) {
1691 /* other end of pipe has been closed */
1692 PIPE_UNLOCK(cpipe);
1693 return (EPIPE);
1694 }
1695 cpipe = PIPE_PEER(cpipe);
1696 break;
1697 default:
1698 PIPE_UNLOCK(cpipe);
1699 return (EINVAL);
1700 }
1701
1702 kn->kn_hook = cpipe;
1703 knlist_add(&cpipe->pipe_sel.si_note, kn, 1);
1704 PIPE_UNLOCK(cpipe);
1705 return (0);
1706 }
1707
1708 static void
filt_pipedetach(struct knote * kn)1709 filt_pipedetach(struct knote *kn)
1710 {
1711 struct pipe *cpipe = kn->kn_hook;
1712
1713 PIPE_LOCK(cpipe);
1714 knlist_remove(&cpipe->pipe_sel.si_note, kn, 1);
1715 PIPE_UNLOCK(cpipe);
1716 }
1717
1718 /*ARGSUSED*/
1719 static int
filt_piperead(struct knote * kn,long hint)1720 filt_piperead(struct knote *kn, long hint)
1721 {
1722 struct pipe *rpipe = kn->kn_hook;
1723 struct pipe *wpipe = rpipe->pipe_peer;
1724 int ret;
1725
1726 PIPE_LOCK_ASSERT(rpipe, MA_OWNED);
1727 kn->kn_data = rpipe->pipe_buffer.cnt;
1728 if (kn->kn_data == 0)
1729 kn->kn_data = rpipe->pipe_map.cnt;
1730
1731 if ((rpipe->pipe_state & PIPE_EOF) ||
1732 wpipe->pipe_present != PIPE_ACTIVE ||
1733 (wpipe->pipe_state & PIPE_EOF)) {
1734 kn->kn_flags |= EV_EOF;
1735 return (1);
1736 }
1737 ret = kn->kn_data > 0;
1738 return ret;
1739 }
1740
1741 /*ARGSUSED*/
1742 static int
filt_pipewrite(struct knote * kn,long hint)1743 filt_pipewrite(struct knote *kn, long hint)
1744 {
1745 struct pipe *wpipe;
1746
1747 /*
1748 * If this end of the pipe is closed, the knote was removed from the
1749 * knlist and the list lock (i.e., the pipe lock) is therefore not held.
1750 */
1751 wpipe = kn->kn_hook;
1752 if (wpipe->pipe_present != PIPE_ACTIVE ||
1753 (wpipe->pipe_state & PIPE_EOF)) {
1754 kn->kn_data = 0;
1755 kn->kn_flags |= EV_EOF;
1756 return (1);
1757 }
1758 PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
1759 kn->kn_data = (wpipe->pipe_buffer.size > 0) ?
1760 (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) : PIPE_BUF;
1761 if (wpipe->pipe_state & PIPE_DIRECTW)
1762 kn->kn_data = 0;
1763
1764 return (kn->kn_data >= PIPE_BUF);
1765 }
1766
1767 static void
filt_pipedetach_notsup(struct knote * kn)1768 filt_pipedetach_notsup(struct knote *kn)
1769 {
1770
1771 }
1772
1773 static int
filt_pipenotsup(struct knote * kn,long hint)1774 filt_pipenotsup(struct knote *kn, long hint)
1775 {
1776
1777 return (0);
1778 }
1779