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_type & PIPE_TYPE_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 int pipe_create(struct pipe *pipe, bool backing);
230 static int 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 static void pipe_timestamp(struct timespec *tsp);
234 #ifndef PIPE_NODIRECT
235 static int pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio);
236 static void pipe_destroy_write_buffer(struct pipe *wpipe);
237 static int pipe_direct_write(struct pipe *wpipe, struct uio *uio);
238 static void pipe_clone_write_buffer(struct pipe *wpipe);
239 #endif
240 static int pipespace(struct pipe *cpipe, int size);
241 static int pipespace_new(struct pipe *cpipe, int size);
242
243 static int pipe_zone_ctor(void *mem, int size, void *arg, int flags);
244 static int pipe_zone_init(void *mem, int size, int flags);
245 static void pipe_zone_fini(void *mem, int size);
246
247 static uma_zone_t pipe_zone;
248 static struct unrhdr64 pipeino_unr;
249 static dev_t pipedev_ino;
250
251 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_ANY, pipeinit, NULL);
252
253 static void
pipeinit(void * dummy __unused)254 pipeinit(void *dummy __unused)
255 {
256
257 pipe_zone = uma_zcreate("pipe", sizeof(struct pipepair),
258 pipe_zone_ctor, NULL, pipe_zone_init, pipe_zone_fini,
259 UMA_ALIGN_PTR, 0);
260 KASSERT(pipe_zone != NULL, ("pipe_zone not initialized"));
261 new_unrhdr64(&pipeino_unr, 1);
262 pipedev_ino = devfs_alloc_cdp_inode();
263 KASSERT(pipedev_ino > 0, ("pipe dev inode not initialized"));
264 }
265
266 static int
pipe_zone_ctor(void * mem,int size,void * arg,int flags)267 pipe_zone_ctor(void *mem, int size, void *arg, int flags)
268 {
269 struct pipepair *pp;
270 struct pipe *rpipe, *wpipe;
271
272 KASSERT(size == sizeof(*pp), ("pipe_zone_ctor: wrong size"));
273
274 pp = (struct pipepair *)mem;
275
276 /*
277 * We zero both pipe endpoints to make sure all the kmem pointers
278 * are NULL, flag fields are zero'd, etc. We timestamp both
279 * endpoints with the same time.
280 */
281 rpipe = &pp->pp_rpipe;
282 bzero(rpipe, sizeof(*rpipe));
283 pipe_timestamp(&rpipe->pipe_ctime);
284 rpipe->pipe_atime = rpipe->pipe_mtime = rpipe->pipe_ctime;
285
286 wpipe = &pp->pp_wpipe;
287 bzero(wpipe, sizeof(*wpipe));
288 wpipe->pipe_ctime = rpipe->pipe_ctime;
289 wpipe->pipe_atime = wpipe->pipe_mtime = rpipe->pipe_ctime;
290
291 rpipe->pipe_peer = wpipe;
292 rpipe->pipe_pair = pp;
293 wpipe->pipe_peer = rpipe;
294 wpipe->pipe_pair = pp;
295
296 /*
297 * Mark both endpoints as present; they will later get free'd
298 * one at a time. When both are free'd, then the whole pair
299 * is released.
300 */
301 rpipe->pipe_present = PIPE_ACTIVE;
302 wpipe->pipe_present = PIPE_ACTIVE;
303
304 /*
305 * Eventually, the MAC Framework may initialize the label
306 * in ctor or init, but for now we do it elswhere to avoid
307 * blocking in ctor or init.
308 */
309 pp->pp_label = NULL;
310
311 return (0);
312 }
313
314 static int
pipe_zone_init(void * mem,int size,int flags)315 pipe_zone_init(void *mem, int size, int flags)
316 {
317 struct pipepair *pp;
318
319 KASSERT(size == sizeof(*pp), ("pipe_zone_init: wrong size"));
320
321 pp = (struct pipepair *)mem;
322
323 mtx_init(&pp->pp_mtx, "pipe mutex", NULL, MTX_DEF | MTX_NEW);
324 return (0);
325 }
326
327 static void
pipe_zone_fini(void * mem,int size)328 pipe_zone_fini(void *mem, int size)
329 {
330 struct pipepair *pp;
331
332 KASSERT(size == sizeof(*pp), ("pipe_zone_fini: wrong size"));
333
334 pp = (struct pipepair *)mem;
335
336 mtx_destroy(&pp->pp_mtx);
337 }
338
339 static int
pipe_paircreate(struct thread * td,struct pipepair ** p_pp)340 pipe_paircreate(struct thread *td, struct pipepair **p_pp)
341 {
342 struct pipepair *pp;
343 struct pipe *rpipe, *wpipe;
344 int error;
345
346 *p_pp = pp = uma_zalloc(pipe_zone, M_WAITOK);
347 #ifdef MAC
348 /*
349 * The MAC label is shared between the connected endpoints. As a
350 * result mac_pipe_init() and mac_pipe_create() are called once
351 * for the pair, and not on the endpoints.
352 */
353 mac_pipe_init(pp);
354 mac_pipe_create(td->td_ucred, pp);
355 #endif
356 rpipe = &pp->pp_rpipe;
357 wpipe = &pp->pp_wpipe;
358
359 knlist_init_mtx(&rpipe->pipe_sel.si_note, PIPE_MTX(rpipe));
360 knlist_init_mtx(&wpipe->pipe_sel.si_note, PIPE_MTX(wpipe));
361
362 /*
363 * Only the forward direction pipe is backed by big buffer by
364 * default.
365 */
366 error = pipe_create(rpipe, true);
367 if (error != 0)
368 goto fail;
369 error = pipe_create(wpipe, false);
370 if (error != 0) {
371 /*
372 * This cleanup leaves the pipe inode number for rpipe
373 * still allocated, but never used. We do not free
374 * inode numbers for opened pipes, which is required
375 * for correctness because numbers must be unique.
376 * But also it avoids any memory use by the unr
377 * allocator, so stashing away the transient inode
378 * number is reasonable.
379 */
380 pipe_free_kmem(rpipe);
381 goto fail;
382 }
383
384 rpipe->pipe_state |= PIPE_DIRECTOK;
385 wpipe->pipe_state |= PIPE_DIRECTOK;
386 return (0);
387
388 fail:
389 knlist_destroy(&rpipe->pipe_sel.si_note);
390 knlist_destroy(&wpipe->pipe_sel.si_note);
391 #ifdef MAC
392 mac_pipe_destroy(pp);
393 #endif
394 uma_zfree(pipe_zone, pp);
395 return (error);
396 }
397
398 int
pipe_named_ctor(struct pipe ** ppipe,struct thread * td)399 pipe_named_ctor(struct pipe **ppipe, struct thread *td)
400 {
401 struct pipepair *pp;
402 int error;
403
404 error = pipe_paircreate(td, &pp);
405 if (error != 0)
406 return (error);
407 pp->pp_rpipe.pipe_type |= PIPE_TYPE_NAMED;
408 *ppipe = &pp->pp_rpipe;
409 return (0);
410 }
411
412 void
pipe_dtor(struct pipe * dpipe)413 pipe_dtor(struct pipe *dpipe)
414 {
415 struct pipe *peer;
416
417 peer = (dpipe->pipe_type & PIPE_TYPE_NAMED) != 0 ? dpipe->pipe_peer : NULL;
418 funsetown(&dpipe->pipe_sigio);
419 pipeclose(dpipe);
420 if (peer != NULL) {
421 funsetown(&peer->pipe_sigio);
422 pipeclose(peer);
423 }
424 }
425
426 /*
427 * Get a timestamp.
428 *
429 * This used to be vfs_timestamp but the higher precision is unnecessary and
430 * can very negatively affect performance in virtualized environments (e.g., on
431 * vms running on amd64 when using the rdtscp instruction).
432 */
433 static void
pipe_timestamp(struct timespec * tsp)434 pipe_timestamp(struct timespec *tsp)
435 {
436
437 getnanotime(tsp);
438 }
439
440 /*
441 * The pipe system call for the DTYPE_PIPE type of pipes. If we fail, let
442 * the zone pick up the pieces via pipeclose().
443 */
444 int
kern_pipe(struct thread * td,int fildes[2],int flags,struct filecaps * fcaps1,struct filecaps * fcaps2)445 kern_pipe(struct thread *td, int fildes[2], int flags, struct filecaps *fcaps1,
446 struct filecaps *fcaps2)
447 {
448 struct file *rf, *wf;
449 struct pipe *rpipe, *wpipe;
450 struct pipepair *pp;
451 int fd, fflags, error;
452
453 error = pipe_paircreate(td, &pp);
454 if (error != 0)
455 return (error);
456 rpipe = &pp->pp_rpipe;
457 wpipe = &pp->pp_wpipe;
458 error = falloc_caps(td, &rf, &fd, flags, fcaps1);
459 if (error) {
460 pipeclose(rpipe);
461 pipeclose(wpipe);
462 return (error);
463 }
464 /* An extra reference on `rf' has been held for us by falloc_caps(). */
465 fildes[0] = fd;
466
467 fflags = FREAD | FWRITE;
468 if ((flags & O_NONBLOCK) != 0)
469 fflags |= FNONBLOCK;
470
471 /*
472 * Warning: once we've gotten past allocation of the fd for the
473 * read-side, we can only drop the read side via fdrop() in order
474 * to avoid races against processes which manage to dup() the read
475 * side while we are blocked trying to allocate the write side.
476 */
477 finit(rf, fflags, DTYPE_PIPE, rpipe, &pipeops);
478 error = falloc_caps(td, &wf, &fd, flags, fcaps2);
479 if (error) {
480 fdclose(td, rf, fildes[0]);
481 fdrop(rf, td);
482 /* rpipe has been closed by fdrop(). */
483 pipeclose(wpipe);
484 return (error);
485 }
486 /* An extra reference on `wf' has been held for us by falloc_caps(). */
487 finit(wf, fflags, DTYPE_PIPE, wpipe, &pipeops);
488 fdrop(wf, td);
489 fildes[1] = fd;
490 fdrop(rf, td);
491
492 return (0);
493 }
494
495 #ifdef COMPAT_FREEBSD10
496 /* ARGSUSED */
497 int
freebsd10_pipe(struct thread * td,struct freebsd10_pipe_args * uap __unused)498 freebsd10_pipe(struct thread *td, struct freebsd10_pipe_args *uap __unused)
499 {
500 int error;
501 int fildes[2];
502
503 error = kern_pipe(td, fildes, 0, NULL, NULL);
504 if (error)
505 return (error);
506
507 td->td_retval[0] = fildes[0];
508 td->td_retval[1] = fildes[1];
509
510 return (0);
511 }
512 #endif
513
514 int
sys_pipe2(struct thread * td,struct pipe2_args * uap)515 sys_pipe2(struct thread *td, struct pipe2_args *uap)
516 {
517 int error, fildes[2];
518
519 if (uap->flags & ~(O_CLOEXEC | O_NONBLOCK))
520 return (EINVAL);
521 error = kern_pipe(td, fildes, uap->flags, NULL, NULL);
522 if (error)
523 return (error);
524 error = copyout(fildes, uap->fildes, 2 * sizeof(int));
525 if (error) {
526 (void)kern_close(td, fildes[0]);
527 (void)kern_close(td, fildes[1]);
528 }
529 return (error);
530 }
531
532 /*
533 * Allocate kva for pipe circular buffer, the space is pageable
534 * This routine will 'realloc' the size of a pipe safely, if it fails
535 * it will retain the old buffer.
536 * If it fails it will return ENOMEM.
537 */
538 static int
pipespace_new(struct pipe * cpipe,int size)539 pipespace_new(struct pipe *cpipe, int size)
540 {
541 caddr_t buffer;
542 int error, cnt, firstseg;
543 static int curfail = 0;
544 static struct timeval lastfail;
545
546 KASSERT(!mtx_owned(PIPE_MTX(cpipe)), ("pipespace: pipe mutex locked"));
547 KASSERT(!(cpipe->pipe_state & PIPE_DIRECTW),
548 ("pipespace: resize of direct writes not allowed"));
549 retry:
550 cnt = cpipe->pipe_buffer.cnt;
551 if (cnt > size)
552 size = cnt;
553
554 size = round_page(size);
555 buffer = (caddr_t) vm_map_min(pipe_map);
556
557 error = vm_map_find(pipe_map, NULL, 0, (vm_offset_t *)&buffer, size, 0,
558 VMFS_ANY_SPACE, VM_PROT_RW, VM_PROT_RW, 0);
559 if (error != KERN_SUCCESS) {
560 if (cpipe->pipe_buffer.buffer == NULL &&
561 size > SMALL_PIPE_SIZE) {
562 size = SMALL_PIPE_SIZE;
563 pipefragretry++;
564 goto retry;
565 }
566 if (cpipe->pipe_buffer.buffer == NULL) {
567 pipeallocfail++;
568 if (ppsratecheck(&lastfail, &curfail, 1))
569 printf("kern.ipc.maxpipekva exceeded; see tuning(7)\n");
570 } else {
571 piperesizefail++;
572 }
573 return (ENOMEM);
574 }
575
576 /* copy data, then free old resources if we're resizing */
577 if (cnt > 0) {
578 if (cpipe->pipe_buffer.in <= cpipe->pipe_buffer.out) {
579 firstseg = cpipe->pipe_buffer.size - cpipe->pipe_buffer.out;
580 bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out],
581 buffer, firstseg);
582 if ((cnt - firstseg) > 0)
583 bcopy(cpipe->pipe_buffer.buffer, &buffer[firstseg],
584 cpipe->pipe_buffer.in);
585 } else {
586 bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out],
587 buffer, cnt);
588 }
589 }
590 pipe_free_kmem(cpipe);
591 cpipe->pipe_buffer.buffer = buffer;
592 cpipe->pipe_buffer.size = size;
593 cpipe->pipe_buffer.in = cnt;
594 cpipe->pipe_buffer.out = 0;
595 cpipe->pipe_buffer.cnt = cnt;
596 atomic_add_long(&amountpipekva, cpipe->pipe_buffer.size);
597 return (0);
598 }
599
600 /*
601 * Wrapper for pipespace_new() that performs locking assertions.
602 */
603 static int
pipespace(struct pipe * cpipe,int size)604 pipespace(struct pipe *cpipe, int size)
605 {
606
607 KASSERT(cpipe->pipe_state & PIPE_LOCKFL,
608 ("Unlocked pipe passed to pipespace"));
609 return (pipespace_new(cpipe, size));
610 }
611
612 /*
613 * lock a pipe for I/O, blocking other access
614 */
615 static __inline int
pipelock(struct pipe * cpipe,int catch)616 pipelock(struct pipe *cpipe, int catch)
617 {
618 int error, prio;
619
620 PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
621
622 prio = PRIBIO;
623 if (catch)
624 prio |= PCATCH;
625 while (cpipe->pipe_state & PIPE_LOCKFL) {
626 KASSERT(cpipe->pipe_waiters >= 0,
627 ("%s: bad waiter count %d", __func__,
628 cpipe->pipe_waiters));
629 cpipe->pipe_waiters++;
630 error = msleep(cpipe, PIPE_MTX(cpipe),
631 prio, "pipelk", 0);
632 cpipe->pipe_waiters--;
633 if (error != 0)
634 return (error);
635 }
636 cpipe->pipe_state |= PIPE_LOCKFL;
637 return (0);
638 }
639
640 /*
641 * unlock a pipe I/O lock
642 */
643 static __inline void
pipeunlock(struct pipe * cpipe)644 pipeunlock(struct pipe *cpipe)
645 {
646
647 PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
648 KASSERT(cpipe->pipe_state & PIPE_LOCKFL,
649 ("Unlocked pipe passed to pipeunlock"));
650 KASSERT(cpipe->pipe_waiters >= 0,
651 ("%s: bad waiter count %d", __func__,
652 cpipe->pipe_waiters));
653 cpipe->pipe_state &= ~PIPE_LOCKFL;
654 if (cpipe->pipe_waiters > 0) {
655 wakeup_one(cpipe);
656 }
657 }
658
659 void
pipeselwakeup(struct pipe * cpipe)660 pipeselwakeup(struct pipe *cpipe)
661 {
662
663 PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
664 if (cpipe->pipe_state & PIPE_SEL) {
665 selwakeuppri(&cpipe->pipe_sel, PSOCK);
666 if (!SEL_WAITING(&cpipe->pipe_sel))
667 cpipe->pipe_state &= ~PIPE_SEL;
668 }
669 if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio)
670 pgsigio(&cpipe->pipe_sigio, SIGIO, 0);
671 KNOTE_LOCKED(&cpipe->pipe_sel.si_note, 0);
672 }
673
674 /*
675 * Initialize and allocate VM and memory for pipe. The structure
676 * will start out zero'd from the ctor, so we just manage the kmem.
677 */
678 static int
pipe_create(struct pipe * pipe,bool large_backing)679 pipe_create(struct pipe *pipe, bool large_backing)
680 {
681 int error;
682
683 error = pipespace_new(pipe, !large_backing || amountpipekva >
684 maxpipekva / 2 ? SMALL_PIPE_SIZE : PIPE_SIZE);
685 if (error == 0)
686 pipe->pipe_ino = alloc_unr64(&pipeino_unr);
687 return (error);
688 }
689
690 /* ARGSUSED */
691 static int
pipe_read(struct file * fp,struct uio * uio,struct ucred * active_cred,int flags,struct thread * td)692 pipe_read(struct file *fp, struct uio *uio, struct ucred *active_cred,
693 int flags, struct thread *td)
694 {
695 struct pipe *rpipe;
696 int error;
697 int nread = 0;
698 int size;
699
700 rpipe = fp->f_data;
701 PIPE_LOCK(rpipe);
702 ++rpipe->pipe_busy;
703 error = pipelock(rpipe, 1);
704 if (error)
705 goto unlocked_error;
706
707 #ifdef MAC
708 error = mac_pipe_check_read(active_cred, rpipe->pipe_pair);
709 if (error)
710 goto locked_error;
711 #endif
712 if (amountpipekva > (3 * maxpipekva) / 4) {
713 if ((rpipe->pipe_state & PIPE_DIRECTW) == 0 &&
714 rpipe->pipe_buffer.size > SMALL_PIPE_SIZE &&
715 rpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE &&
716 piperesizeallowed == 1) {
717 PIPE_UNLOCK(rpipe);
718 pipespace(rpipe, SMALL_PIPE_SIZE);
719 PIPE_LOCK(rpipe);
720 }
721 }
722
723 while (uio->uio_resid) {
724 /*
725 * normal pipe buffer receive
726 */
727 if (rpipe->pipe_buffer.cnt > 0) {
728 size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out;
729 if (size > rpipe->pipe_buffer.cnt)
730 size = rpipe->pipe_buffer.cnt;
731 if (size > uio->uio_resid)
732 size = uio->uio_resid;
733
734 PIPE_UNLOCK(rpipe);
735 error = uiomove(
736 &rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out],
737 size, uio);
738 PIPE_LOCK(rpipe);
739 if (error)
740 break;
741
742 rpipe->pipe_buffer.out += size;
743 if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size)
744 rpipe->pipe_buffer.out = 0;
745
746 rpipe->pipe_buffer.cnt -= size;
747
748 /*
749 * If there is no more to read in the pipe, reset
750 * its pointers to the beginning. This improves
751 * cache hit stats.
752 */
753 if (rpipe->pipe_buffer.cnt == 0) {
754 rpipe->pipe_buffer.in = 0;
755 rpipe->pipe_buffer.out = 0;
756 }
757 nread += size;
758 #ifndef PIPE_NODIRECT
759 /*
760 * Direct copy, bypassing a kernel buffer.
761 */
762 } else if ((size = rpipe->pipe_pages.cnt) != 0) {
763 if (size > uio->uio_resid)
764 size = (u_int) uio->uio_resid;
765 PIPE_UNLOCK(rpipe);
766 error = uiomove_fromphys(rpipe->pipe_pages.ms,
767 rpipe->pipe_pages.pos, size, uio);
768 PIPE_LOCK(rpipe);
769 if (error)
770 break;
771 nread += size;
772 rpipe->pipe_pages.pos += size;
773 rpipe->pipe_pages.cnt -= size;
774 if (rpipe->pipe_pages.cnt == 0) {
775 rpipe->pipe_state &= ~PIPE_WANTW;
776 wakeup(rpipe);
777 }
778 #endif
779 } else {
780 /*
781 * detect EOF condition
782 * read returns 0 on EOF, no need to set error
783 */
784 if (rpipe->pipe_state & PIPE_EOF)
785 break;
786
787 /*
788 * If the "write-side" has been blocked, wake it up now.
789 */
790 if (rpipe->pipe_state & PIPE_WANTW) {
791 rpipe->pipe_state &= ~PIPE_WANTW;
792 wakeup(rpipe);
793 }
794
795 /*
796 * Break if some data was read.
797 */
798 if (nread > 0)
799 break;
800
801 /*
802 * Unlock the pipe buffer for our remaining processing.
803 * We will either break out with an error or we will
804 * sleep and relock to loop.
805 */
806 pipeunlock(rpipe);
807
808 /*
809 * Handle non-blocking mode operation or
810 * wait for more data.
811 */
812 if (fp->f_flag & FNONBLOCK) {
813 error = EAGAIN;
814 } else {
815 rpipe->pipe_state |= PIPE_WANTR;
816 if ((error = msleep(rpipe, PIPE_MTX(rpipe),
817 PRIBIO | PCATCH,
818 "piperd", 0)) == 0)
819 error = pipelock(rpipe, 1);
820 }
821 if (error)
822 goto unlocked_error;
823 }
824 }
825 #ifdef MAC
826 locked_error:
827 #endif
828 pipeunlock(rpipe);
829
830 /* XXX: should probably do this before getting any locks. */
831 if (error == 0)
832 pipe_timestamp(&rpipe->pipe_atime);
833 unlocked_error:
834 --rpipe->pipe_busy;
835
836 /*
837 * PIPE_WANT processing only makes sense if pipe_busy is 0.
838 */
839 if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) {
840 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW);
841 wakeup(rpipe);
842 } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) {
843 /*
844 * Handle write blocking hysteresis.
845 */
846 if (rpipe->pipe_state & PIPE_WANTW) {
847 rpipe->pipe_state &= ~PIPE_WANTW;
848 wakeup(rpipe);
849 }
850 }
851
852 /*
853 * Only wake up writers if there was actually something read.
854 * Otherwise, when calling read(2) at EOF, a spurious wakeup occurs.
855 */
856 if (nread > 0 &&
857 rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt >= PIPE_BUF)
858 pipeselwakeup(rpipe);
859
860 PIPE_UNLOCK(rpipe);
861 if (nread > 0)
862 td->td_ru.ru_msgrcv++;
863 return (error);
864 }
865
866 #ifndef PIPE_NODIRECT
867 /*
868 * Map the sending processes' buffer into kernel space and wire it.
869 * This is similar to a physical write operation.
870 */
871 static int
pipe_build_write_buffer(struct pipe * wpipe,struct uio * uio)872 pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio)
873 {
874 u_int size;
875 int i;
876
877 PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
878 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) == 0,
879 ("%s: PIPE_DIRECTW set on %p", __func__, wpipe));
880 KASSERT(wpipe->pipe_pages.cnt == 0,
881 ("%s: pipe map for %p contains residual data", __func__, wpipe));
882
883 if (uio->uio_iov->iov_len > wpipe->pipe_buffer.size)
884 size = wpipe->pipe_buffer.size;
885 else
886 size = uio->uio_iov->iov_len;
887
888 wpipe->pipe_state |= PIPE_DIRECTW;
889 PIPE_UNLOCK(wpipe);
890 i = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map,
891 (vm_offset_t)uio->uio_iov->iov_base, size, VM_PROT_READ,
892 wpipe->pipe_pages.ms, PIPENPAGES);
893 PIPE_LOCK(wpipe);
894 if (i < 0) {
895 wpipe->pipe_state &= ~PIPE_DIRECTW;
896 return (EFAULT);
897 }
898
899 wpipe->pipe_pages.npages = i;
900 wpipe->pipe_pages.pos =
901 ((vm_offset_t) uio->uio_iov->iov_base) & PAGE_MASK;
902 wpipe->pipe_pages.cnt = size;
903
904 uio->uio_iov->iov_len -= size;
905 uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + size;
906 if (uio->uio_iov->iov_len == 0)
907 uio->uio_iov++;
908 uio->uio_resid -= size;
909 uio->uio_offset += size;
910 return (0);
911 }
912
913 /*
914 * Unwire the process buffer.
915 */
916 static void
pipe_destroy_write_buffer(struct pipe * wpipe)917 pipe_destroy_write_buffer(struct pipe *wpipe)
918 {
919
920 PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
921 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) != 0,
922 ("%s: PIPE_DIRECTW not set on %p", __func__, wpipe));
923 KASSERT(wpipe->pipe_pages.cnt == 0,
924 ("%s: pipe map for %p contains residual data", __func__, wpipe));
925
926 wpipe->pipe_state &= ~PIPE_DIRECTW;
927 vm_page_unhold_pages(wpipe->pipe_pages.ms, wpipe->pipe_pages.npages);
928 wpipe->pipe_pages.npages = 0;
929 }
930
931 /*
932 * In the case of a signal, the writing process might go away. This
933 * code copies the data into the circular buffer so that the source
934 * pages can be freed without loss of data.
935 */
936 static void
pipe_clone_write_buffer(struct pipe * wpipe)937 pipe_clone_write_buffer(struct pipe *wpipe)
938 {
939 struct uio uio;
940 struct iovec iov;
941 int size;
942 int pos;
943
944 PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
945 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) != 0,
946 ("%s: PIPE_DIRECTW not set on %p", __func__, wpipe));
947
948 size = wpipe->pipe_pages.cnt;
949 pos = wpipe->pipe_pages.pos;
950 wpipe->pipe_pages.cnt = 0;
951
952 wpipe->pipe_buffer.in = size;
953 wpipe->pipe_buffer.out = 0;
954 wpipe->pipe_buffer.cnt = size;
955
956 PIPE_UNLOCK(wpipe);
957 iov.iov_base = wpipe->pipe_buffer.buffer;
958 iov.iov_len = size;
959 uio.uio_iov = &iov;
960 uio.uio_iovcnt = 1;
961 uio.uio_offset = 0;
962 uio.uio_resid = size;
963 uio.uio_segflg = UIO_SYSSPACE;
964 uio.uio_rw = UIO_READ;
965 uio.uio_td = curthread;
966 uiomove_fromphys(wpipe->pipe_pages.ms, pos, size, &uio);
967 PIPE_LOCK(wpipe);
968 pipe_destroy_write_buffer(wpipe);
969 }
970
971 /*
972 * This implements the pipe buffer write mechanism. Note that only
973 * a direct write OR a normal pipe write can be pending at any given time.
974 * If there are any characters in the pipe buffer, the direct write will
975 * be deferred until the receiving process grabs all of the bytes from
976 * the pipe buffer. Then the direct mapping write is set-up.
977 */
978 static int
pipe_direct_write(struct pipe * wpipe,struct uio * uio)979 pipe_direct_write(struct pipe *wpipe, struct uio *uio)
980 {
981 int error;
982
983 retry:
984 PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
985 if ((wpipe->pipe_state & PIPE_EOF) != 0) {
986 error = EPIPE;
987 goto error1;
988 }
989 if (wpipe->pipe_state & PIPE_DIRECTW) {
990 if (wpipe->pipe_state & PIPE_WANTR) {
991 wpipe->pipe_state &= ~PIPE_WANTR;
992 wakeup(wpipe);
993 }
994 pipeselwakeup(wpipe);
995 wpipe->pipe_state |= PIPE_WANTW;
996 pipeunlock(wpipe);
997 error = msleep(wpipe, PIPE_MTX(wpipe),
998 PRIBIO | PCATCH, "pipdww", 0);
999 pipelock(wpipe, 0);
1000 if (error != 0)
1001 goto error1;
1002 goto retry;
1003 }
1004 if (wpipe->pipe_buffer.cnt > 0) {
1005 if (wpipe->pipe_state & PIPE_WANTR) {
1006 wpipe->pipe_state &= ~PIPE_WANTR;
1007 wakeup(wpipe);
1008 }
1009 pipeselwakeup(wpipe);
1010 wpipe->pipe_state |= PIPE_WANTW;
1011 pipeunlock(wpipe);
1012 error = msleep(wpipe, PIPE_MTX(wpipe),
1013 PRIBIO | PCATCH, "pipdwc", 0);
1014 pipelock(wpipe, 0);
1015 if (error != 0)
1016 goto error1;
1017 goto retry;
1018 }
1019
1020 error = pipe_build_write_buffer(wpipe, uio);
1021 if (error) {
1022 goto error1;
1023 }
1024
1025 while (wpipe->pipe_pages.cnt != 0 &&
1026 (wpipe->pipe_state & PIPE_EOF) == 0) {
1027 if (wpipe->pipe_state & PIPE_WANTR) {
1028 wpipe->pipe_state &= ~PIPE_WANTR;
1029 wakeup(wpipe);
1030 }
1031 pipeselwakeup(wpipe);
1032 wpipe->pipe_state |= PIPE_WANTW;
1033 pipeunlock(wpipe);
1034 error = msleep(wpipe, PIPE_MTX(wpipe), PRIBIO | PCATCH,
1035 "pipdwt", 0);
1036 pipelock(wpipe, 0);
1037 if (error != 0)
1038 break;
1039 }
1040
1041 if ((wpipe->pipe_state & PIPE_EOF) != 0) {
1042 wpipe->pipe_pages.cnt = 0;
1043 pipe_destroy_write_buffer(wpipe);
1044 pipeselwakeup(wpipe);
1045 error = EPIPE;
1046 } else if (error == EINTR || error == ERESTART) {
1047 pipe_clone_write_buffer(wpipe);
1048 } else {
1049 pipe_destroy_write_buffer(wpipe);
1050 }
1051 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) == 0,
1052 ("pipe %p leaked PIPE_DIRECTW", wpipe));
1053 return (error);
1054
1055 error1:
1056 wakeup(wpipe);
1057 return (error);
1058 }
1059 #endif
1060
1061 static int
pipe_write(struct file * fp,struct uio * uio,struct ucred * active_cred,int flags,struct thread * td)1062 pipe_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
1063 int flags, struct thread *td)
1064 {
1065 struct pipe *wpipe, *rpipe;
1066 ssize_t orig_resid;
1067 int desiredsize, error;
1068
1069 rpipe = fp->f_data;
1070 wpipe = PIPE_PEER(rpipe);
1071 PIPE_LOCK(rpipe);
1072 error = pipelock(wpipe, 1);
1073 if (error) {
1074 PIPE_UNLOCK(rpipe);
1075 return (error);
1076 }
1077 /*
1078 * detect loss of pipe read side, issue SIGPIPE if lost.
1079 */
1080 if (wpipe->pipe_present != PIPE_ACTIVE ||
1081 (wpipe->pipe_state & PIPE_EOF)) {
1082 pipeunlock(wpipe);
1083 PIPE_UNLOCK(rpipe);
1084 return (EPIPE);
1085 }
1086 #ifdef MAC
1087 error = mac_pipe_check_write(active_cred, wpipe->pipe_pair);
1088 if (error) {
1089 pipeunlock(wpipe);
1090 PIPE_UNLOCK(rpipe);
1091 return (error);
1092 }
1093 #endif
1094 ++wpipe->pipe_busy;
1095
1096 /* Choose a larger size if it's advantageous */
1097 desiredsize = max(SMALL_PIPE_SIZE, wpipe->pipe_buffer.size);
1098 while (desiredsize < wpipe->pipe_buffer.cnt + uio->uio_resid) {
1099 if (piperesizeallowed != 1)
1100 break;
1101 if (amountpipekva > maxpipekva / 2)
1102 break;
1103 if (desiredsize == BIG_PIPE_SIZE)
1104 break;
1105 desiredsize = desiredsize * 2;
1106 }
1107
1108 /* Choose a smaller size if we're in a OOM situation */
1109 if (amountpipekva > (3 * maxpipekva) / 4 &&
1110 wpipe->pipe_buffer.size > SMALL_PIPE_SIZE &&
1111 wpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE &&
1112 piperesizeallowed == 1)
1113 desiredsize = SMALL_PIPE_SIZE;
1114
1115 /* Resize if the above determined that a new size was necessary */
1116 if (desiredsize != wpipe->pipe_buffer.size &&
1117 (wpipe->pipe_state & PIPE_DIRECTW) == 0) {
1118 PIPE_UNLOCK(wpipe);
1119 pipespace(wpipe, desiredsize);
1120 PIPE_LOCK(wpipe);
1121 }
1122 MPASS(wpipe->pipe_buffer.size != 0);
1123
1124 orig_resid = uio->uio_resid;
1125
1126 while (uio->uio_resid) {
1127 int space;
1128
1129 if (wpipe->pipe_state & PIPE_EOF) {
1130 error = EPIPE;
1131 break;
1132 }
1133 #ifndef PIPE_NODIRECT
1134 /*
1135 * If the transfer is large, we can gain performance if
1136 * we do process-to-process copies directly.
1137 * If the write is non-blocking, we don't use the
1138 * direct write mechanism.
1139 *
1140 * The direct write mechanism will detect the reader going
1141 * away on us.
1142 */
1143 if (uio->uio_segflg == UIO_USERSPACE &&
1144 uio->uio_iov->iov_len >= PIPE_MINDIRECT &&
1145 wpipe->pipe_buffer.size >= PIPE_MINDIRECT &&
1146 (fp->f_flag & FNONBLOCK) == 0) {
1147 error = pipe_direct_write(wpipe, uio);
1148 if (error != 0)
1149 break;
1150 continue;
1151 }
1152 #endif
1153
1154 /*
1155 * Pipe buffered writes cannot be coincidental with
1156 * direct writes. We wait until the currently executing
1157 * direct write is completed before we start filling the
1158 * pipe buffer. We break out if a signal occurs or the
1159 * reader goes away.
1160 */
1161 if (wpipe->pipe_pages.cnt != 0) {
1162 if (wpipe->pipe_state & PIPE_WANTR) {
1163 wpipe->pipe_state &= ~PIPE_WANTR;
1164 wakeup(wpipe);
1165 }
1166 pipeselwakeup(wpipe);
1167 wpipe->pipe_state |= PIPE_WANTW;
1168 pipeunlock(wpipe);
1169 error = msleep(wpipe, PIPE_MTX(rpipe), PRIBIO | PCATCH,
1170 "pipbww", 0);
1171 pipelock(wpipe, 0);
1172 if (error != 0)
1173 break;
1174 continue;
1175 }
1176
1177 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
1178
1179 /* Writes of size <= PIPE_BUF must be atomic. */
1180 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF))
1181 space = 0;
1182
1183 if (space > 0) {
1184 int size; /* Transfer size */
1185 int segsize; /* first segment to transfer */
1186
1187 /*
1188 * Transfer size is minimum of uio transfer
1189 * and free space in pipe buffer.
1190 */
1191 if (space > uio->uio_resid)
1192 size = uio->uio_resid;
1193 else
1194 size = space;
1195 /*
1196 * First segment to transfer is minimum of
1197 * transfer size and contiguous space in
1198 * pipe buffer. If first segment to transfer
1199 * is less than the transfer size, we've got
1200 * a wraparound in the buffer.
1201 */
1202 segsize = wpipe->pipe_buffer.size -
1203 wpipe->pipe_buffer.in;
1204 if (segsize > size)
1205 segsize = size;
1206
1207 /* Transfer first segment */
1208
1209 PIPE_UNLOCK(rpipe);
1210 error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in],
1211 segsize, uio);
1212 PIPE_LOCK(rpipe);
1213
1214 if (error == 0 && segsize < size) {
1215 KASSERT(wpipe->pipe_buffer.in + segsize ==
1216 wpipe->pipe_buffer.size,
1217 ("Pipe buffer wraparound disappeared"));
1218 /*
1219 * Transfer remaining part now, to
1220 * support atomic writes. Wraparound
1221 * happened.
1222 */
1223
1224 PIPE_UNLOCK(rpipe);
1225 error = uiomove(
1226 &wpipe->pipe_buffer.buffer[0],
1227 size - segsize, uio);
1228 PIPE_LOCK(rpipe);
1229 }
1230 if (error == 0) {
1231 wpipe->pipe_buffer.in += size;
1232 if (wpipe->pipe_buffer.in >=
1233 wpipe->pipe_buffer.size) {
1234 KASSERT(wpipe->pipe_buffer.in ==
1235 size - segsize +
1236 wpipe->pipe_buffer.size,
1237 ("Expected wraparound bad"));
1238 wpipe->pipe_buffer.in = size - segsize;
1239 }
1240
1241 wpipe->pipe_buffer.cnt += size;
1242 KASSERT(wpipe->pipe_buffer.cnt <=
1243 wpipe->pipe_buffer.size,
1244 ("Pipe buffer overflow"));
1245 }
1246 if (error != 0)
1247 break;
1248 continue;
1249 } else {
1250 /*
1251 * If the "read-side" has been blocked, wake it up now.
1252 */
1253 if (wpipe->pipe_state & PIPE_WANTR) {
1254 wpipe->pipe_state &= ~PIPE_WANTR;
1255 wakeup(wpipe);
1256 }
1257
1258 /*
1259 * don't block on non-blocking I/O
1260 */
1261 if (fp->f_flag & FNONBLOCK) {
1262 error = EAGAIN;
1263 break;
1264 }
1265
1266 /*
1267 * We have no more space and have something to offer,
1268 * wake up select/poll.
1269 */
1270 pipeselwakeup(wpipe);
1271
1272 wpipe->pipe_state |= PIPE_WANTW;
1273 pipeunlock(wpipe);
1274 error = msleep(wpipe, PIPE_MTX(rpipe),
1275 PRIBIO | PCATCH, "pipewr", 0);
1276 pipelock(wpipe, 0);
1277 if (error != 0)
1278 break;
1279 continue;
1280 }
1281 }
1282
1283 --wpipe->pipe_busy;
1284
1285 if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) {
1286 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR);
1287 wakeup(wpipe);
1288 } else if (wpipe->pipe_buffer.cnt > 0) {
1289 /*
1290 * If we have put any characters in the buffer, we wake up
1291 * the reader.
1292 */
1293 if (wpipe->pipe_state & PIPE_WANTR) {
1294 wpipe->pipe_state &= ~PIPE_WANTR;
1295 wakeup(wpipe);
1296 }
1297 }
1298
1299 /*
1300 * Don't return EPIPE if any byte was written.
1301 * EINTR and other interrupts are handled by generic I/O layer.
1302 * Do not pretend that I/O succeeded for obvious user error
1303 * like EFAULT.
1304 */
1305 if (uio->uio_resid != orig_resid && error == EPIPE)
1306 error = 0;
1307
1308 if (error == 0)
1309 pipe_timestamp(&wpipe->pipe_mtime);
1310
1311 /*
1312 * We have something to offer,
1313 * wake up select/poll.
1314 */
1315 if (wpipe->pipe_buffer.cnt)
1316 pipeselwakeup(wpipe);
1317
1318 pipeunlock(wpipe);
1319 PIPE_UNLOCK(rpipe);
1320 if (uio->uio_resid != orig_resid)
1321 td->td_ru.ru_msgsnd++;
1322 return (error);
1323 }
1324
1325 /* ARGSUSED */
1326 static int
pipe_truncate(struct file * fp,off_t length,struct ucred * active_cred,struct thread * td)1327 pipe_truncate(struct file *fp, off_t length, struct ucred *active_cred,
1328 struct thread *td)
1329 {
1330 struct pipe *cpipe;
1331 int error;
1332
1333 cpipe = fp->f_data;
1334 if (cpipe->pipe_type & PIPE_TYPE_NAMED)
1335 error = vnops.fo_truncate(fp, length, active_cred, td);
1336 else
1337 error = invfo_truncate(fp, length, active_cred, td);
1338 return (error);
1339 }
1340
1341 /*
1342 * we implement a very minimal set of ioctls for compatibility with sockets.
1343 */
1344 static int
pipe_ioctl(struct file * fp,u_long cmd,void * data,struct ucred * active_cred,struct thread * td)1345 pipe_ioctl(struct file *fp, u_long cmd, void *data, struct ucred *active_cred,
1346 struct thread *td)
1347 {
1348 struct pipe *mpipe = fp->f_data;
1349 int error;
1350
1351 PIPE_LOCK(mpipe);
1352
1353 #ifdef MAC
1354 error = mac_pipe_check_ioctl(active_cred, mpipe->pipe_pair, cmd, data);
1355 if (error) {
1356 PIPE_UNLOCK(mpipe);
1357 return (error);
1358 }
1359 #endif
1360
1361 error = 0;
1362 switch (cmd) {
1363 case FIONBIO:
1364 break;
1365
1366 case FIOASYNC:
1367 if (*(int *)data) {
1368 mpipe->pipe_state |= PIPE_ASYNC;
1369 } else {
1370 mpipe->pipe_state &= ~PIPE_ASYNC;
1371 }
1372 break;
1373
1374 case FIONREAD:
1375 if (!(fp->f_flag & FREAD)) {
1376 *(int *)data = 0;
1377 PIPE_UNLOCK(mpipe);
1378 return (0);
1379 }
1380 if (mpipe->pipe_pages.cnt != 0)
1381 *(int *)data = mpipe->pipe_pages.cnt;
1382 else
1383 *(int *)data = mpipe->pipe_buffer.cnt;
1384 break;
1385
1386 case FIOSETOWN:
1387 PIPE_UNLOCK(mpipe);
1388 error = fsetown(*(int *)data, &mpipe->pipe_sigio);
1389 goto out_unlocked;
1390
1391 case FIOGETOWN:
1392 *(int *)data = fgetown(&mpipe->pipe_sigio);
1393 break;
1394
1395 /* This is deprecated, FIOSETOWN should be used instead. */
1396 case TIOCSPGRP:
1397 PIPE_UNLOCK(mpipe);
1398 error = fsetown(-(*(int *)data), &mpipe->pipe_sigio);
1399 goto out_unlocked;
1400
1401 /* This is deprecated, FIOGETOWN should be used instead. */
1402 case TIOCGPGRP:
1403 *(int *)data = -fgetown(&mpipe->pipe_sigio);
1404 break;
1405
1406 default:
1407 error = ENOTTY;
1408 break;
1409 }
1410 PIPE_UNLOCK(mpipe);
1411 out_unlocked:
1412 return (error);
1413 }
1414
1415 static int
pipe_poll(struct file * fp,int events,struct ucred * active_cred,struct thread * td)1416 pipe_poll(struct file *fp, int events, struct ucred *active_cred,
1417 struct thread *td)
1418 {
1419 struct pipe *rpipe;
1420 struct pipe *wpipe;
1421 int levents, revents;
1422 #ifdef MAC
1423 int error;
1424 #endif
1425
1426 revents = 0;
1427 rpipe = fp->f_data;
1428 wpipe = PIPE_PEER(rpipe);
1429 PIPE_LOCK(rpipe);
1430 #ifdef MAC
1431 error = mac_pipe_check_poll(active_cred, rpipe->pipe_pair);
1432 if (error)
1433 goto locked_error;
1434 #endif
1435 if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM))
1436 if (rpipe->pipe_pages.cnt > 0 || rpipe->pipe_buffer.cnt > 0)
1437 revents |= events & (POLLIN | POLLRDNORM);
1438
1439 if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM))
1440 if (wpipe->pipe_present != PIPE_ACTIVE ||
1441 (wpipe->pipe_state & PIPE_EOF) ||
1442 ((wpipe->pipe_state & PIPE_DIRECTW) == 0 &&
1443 ((wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF ||
1444 wpipe->pipe_buffer.size == 0)))
1445 revents |= events & (POLLOUT | POLLWRNORM);
1446
1447 levents = events &
1448 (POLLIN | POLLINIGNEOF | POLLPRI | POLLRDNORM | POLLRDBAND);
1449 if (rpipe->pipe_type & PIPE_TYPE_NAMED && fp->f_flag & FREAD && levents &&
1450 fp->f_pipegen == rpipe->pipe_wgen)
1451 events |= POLLINIGNEOF;
1452
1453 if ((events & POLLINIGNEOF) == 0) {
1454 if (rpipe->pipe_state & PIPE_EOF) {
1455 if (fp->f_flag & FREAD)
1456 revents |= (events & (POLLIN | POLLRDNORM));
1457 if (wpipe->pipe_present != PIPE_ACTIVE ||
1458 (wpipe->pipe_state & PIPE_EOF))
1459 revents |= POLLHUP;
1460 }
1461 }
1462
1463 if (revents == 0) {
1464 /*
1465 * Add ourselves regardless of eventmask as we have to return
1466 * POLLHUP even if it was not asked for.
1467 */
1468 if ((fp->f_flag & FREAD) != 0) {
1469 selrecord(td, &rpipe->pipe_sel);
1470 if (SEL_WAITING(&rpipe->pipe_sel))
1471 rpipe->pipe_state |= PIPE_SEL;
1472 }
1473
1474 if ((fp->f_flag & FWRITE) != 0 &&
1475 wpipe->pipe_present == PIPE_ACTIVE) {
1476 selrecord(td, &wpipe->pipe_sel);
1477 if (SEL_WAITING(&wpipe->pipe_sel))
1478 wpipe->pipe_state |= PIPE_SEL;
1479 }
1480 }
1481 #ifdef MAC
1482 locked_error:
1483 #endif
1484 PIPE_UNLOCK(rpipe);
1485
1486 return (revents);
1487 }
1488
1489 /*
1490 * We shouldn't need locks here as we're doing a read and this should
1491 * be a natural race.
1492 */
1493 static int
pipe_stat(struct file * fp,struct stat * ub,struct ucred * active_cred,struct thread * td)1494 pipe_stat(struct file *fp, struct stat *ub, struct ucred *active_cred,
1495 struct thread *td)
1496 {
1497 struct pipe *pipe;
1498 #ifdef MAC
1499 int error;
1500 #endif
1501
1502 pipe = fp->f_data;
1503 #ifdef MAC
1504 if (mac_pipe_check_stat_enabled()) {
1505 PIPE_LOCK(pipe);
1506 error = mac_pipe_check_stat(active_cred, pipe->pipe_pair);
1507 PIPE_UNLOCK(pipe);
1508 if (error) {
1509 return (error);
1510 }
1511 }
1512 #endif
1513
1514 /* For named pipes ask the underlying filesystem. */
1515 if (pipe->pipe_type & PIPE_TYPE_NAMED) {
1516 return (vnops.fo_stat(fp, ub, active_cred, td));
1517 }
1518
1519 bzero(ub, sizeof(*ub));
1520 ub->st_mode = S_IFIFO;
1521 ub->st_blksize = PAGE_SIZE;
1522 if (pipe->pipe_pages.cnt != 0)
1523 ub->st_size = pipe->pipe_pages.cnt;
1524 else
1525 ub->st_size = pipe->pipe_buffer.cnt;
1526 ub->st_blocks = howmany(ub->st_size, ub->st_blksize);
1527 ub->st_atim = pipe->pipe_atime;
1528 ub->st_mtim = pipe->pipe_mtime;
1529 ub->st_ctim = pipe->pipe_ctime;
1530 ub->st_uid = fp->f_cred->cr_uid;
1531 ub->st_gid = fp->f_cred->cr_gid;
1532 ub->st_dev = pipedev_ino;
1533 ub->st_ino = pipe->pipe_ino;
1534 /*
1535 * Left as 0: st_nlink, st_rdev, st_flags, st_gen.
1536 */
1537 return (0);
1538 }
1539
1540 /* ARGSUSED */
1541 static int
pipe_close(struct file * fp,struct thread * td)1542 pipe_close(struct file *fp, struct thread *td)
1543 {
1544
1545 if (fp->f_vnode != NULL)
1546 return vnops.fo_close(fp, td);
1547 fp->f_ops = &badfileops;
1548 pipe_dtor(fp->f_data);
1549 fp->f_data = NULL;
1550 return (0);
1551 }
1552
1553 static int
pipe_chmod(struct file * fp,mode_t mode,struct ucred * active_cred,struct thread * td)1554 pipe_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, struct thread *td)
1555 {
1556 struct pipe *cpipe;
1557 int error;
1558
1559 cpipe = fp->f_data;
1560 if (cpipe->pipe_type & PIPE_TYPE_NAMED)
1561 error = vn_chmod(fp, mode, active_cred, td);
1562 else
1563 error = invfo_chmod(fp, mode, active_cred, td);
1564 return (error);
1565 }
1566
1567 static int
pipe_chown(struct file * fp,uid_t uid,gid_t gid,struct ucred * active_cred,struct thread * td)1568 pipe_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred,
1569 struct thread *td)
1570 {
1571 struct pipe *cpipe;
1572 int error;
1573
1574 cpipe = fp->f_data;
1575 if (cpipe->pipe_type & PIPE_TYPE_NAMED)
1576 error = vn_chown(fp, uid, gid, active_cred, td);
1577 else
1578 error = invfo_chown(fp, uid, gid, active_cred, td);
1579 return (error);
1580 }
1581
1582 static int
pipe_fill_kinfo(struct file * fp,struct kinfo_file * kif,struct filedesc * fdp)1583 pipe_fill_kinfo(struct file *fp, struct kinfo_file *kif, struct filedesc *fdp)
1584 {
1585 struct pipe *pi;
1586
1587 if (fp->f_type == DTYPE_FIFO)
1588 return (vn_fill_kinfo(fp, kif, fdp));
1589 kif->kf_type = KF_TYPE_PIPE;
1590 pi = fp->f_data;
1591 kif->kf_un.kf_pipe.kf_pipe_addr = (uintptr_t)pi;
1592 kif->kf_un.kf_pipe.kf_pipe_peer = (uintptr_t)pi->pipe_peer;
1593 kif->kf_un.kf_pipe.kf_pipe_buffer_cnt = pi->pipe_buffer.cnt;
1594 return (0);
1595 }
1596
1597 static void
pipe_free_kmem(struct pipe * cpipe)1598 pipe_free_kmem(struct pipe *cpipe)
1599 {
1600
1601 KASSERT(!mtx_owned(PIPE_MTX(cpipe)),
1602 ("pipe_free_kmem: pipe mutex locked"));
1603
1604 if (cpipe->pipe_buffer.buffer != NULL) {
1605 atomic_subtract_long(&amountpipekva, cpipe->pipe_buffer.size);
1606 vm_map_remove(pipe_map,
1607 (vm_offset_t)cpipe->pipe_buffer.buffer,
1608 (vm_offset_t)cpipe->pipe_buffer.buffer + cpipe->pipe_buffer.size);
1609 cpipe->pipe_buffer.buffer = NULL;
1610 }
1611 #ifndef PIPE_NODIRECT
1612 {
1613 cpipe->pipe_pages.cnt = 0;
1614 cpipe->pipe_pages.pos = 0;
1615 cpipe->pipe_pages.npages = 0;
1616 }
1617 #endif
1618 }
1619
1620 /*
1621 * shutdown the pipe
1622 */
1623 static void
pipeclose(struct pipe * cpipe)1624 pipeclose(struct pipe *cpipe)
1625 {
1626 struct pipepair *pp;
1627 struct pipe *ppipe;
1628
1629 KASSERT(cpipe != NULL, ("pipeclose: cpipe == NULL"));
1630
1631 PIPE_LOCK(cpipe);
1632 pipelock(cpipe, 0);
1633 pp = cpipe->pipe_pair;
1634
1635 /*
1636 * If the other side is blocked, wake it up saying that
1637 * we want to close it down.
1638 */
1639 cpipe->pipe_state |= PIPE_EOF;
1640 while (cpipe->pipe_busy) {
1641 wakeup(cpipe);
1642 cpipe->pipe_state |= PIPE_WANT;
1643 pipeunlock(cpipe);
1644 msleep(cpipe, PIPE_MTX(cpipe), PRIBIO, "pipecl", 0);
1645 pipelock(cpipe, 0);
1646 }
1647
1648 pipeselwakeup(cpipe);
1649
1650 /*
1651 * Disconnect from peer, if any.
1652 */
1653 ppipe = cpipe->pipe_peer;
1654 if (ppipe->pipe_present == PIPE_ACTIVE) {
1655 ppipe->pipe_state |= PIPE_EOF;
1656 wakeup(ppipe);
1657 pipeselwakeup(ppipe);
1658 }
1659
1660 /*
1661 * Mark this endpoint as free. Release kmem resources. We
1662 * don't mark this endpoint as unused until we've finished
1663 * doing that, or the pipe might disappear out from under
1664 * us.
1665 */
1666 PIPE_UNLOCK(cpipe);
1667 pipe_free_kmem(cpipe);
1668 PIPE_LOCK(cpipe);
1669 cpipe->pipe_present = PIPE_CLOSING;
1670 pipeunlock(cpipe);
1671
1672 /*
1673 * knlist_clear() may sleep dropping the PIPE_MTX. Set the
1674 * PIPE_FINALIZED, that allows other end to free the
1675 * pipe_pair, only after the knotes are completely dismantled.
1676 */
1677 knlist_clear(&cpipe->pipe_sel.si_note, 1);
1678 cpipe->pipe_present = PIPE_FINALIZED;
1679 seldrain(&cpipe->pipe_sel);
1680 knlist_destroy(&cpipe->pipe_sel.si_note);
1681
1682 /*
1683 * If both endpoints are now closed, release the memory for the
1684 * pipe pair. If not, unlock.
1685 */
1686 if (ppipe->pipe_present == PIPE_FINALIZED) {
1687 PIPE_UNLOCK(cpipe);
1688 #ifdef MAC
1689 mac_pipe_destroy(pp);
1690 #endif
1691 uma_zfree(pipe_zone, cpipe->pipe_pair);
1692 } else
1693 PIPE_UNLOCK(cpipe);
1694 }
1695
1696 /*ARGSUSED*/
1697 static int
pipe_kqfilter(struct file * fp,struct knote * kn)1698 pipe_kqfilter(struct file *fp, struct knote *kn)
1699 {
1700 struct pipe *cpipe;
1701
1702 /*
1703 * If a filter is requested that is not supported by this file
1704 * descriptor, don't return an error, but also don't ever generate an
1705 * event.
1706 */
1707 if ((kn->kn_filter == EVFILT_READ) && !(fp->f_flag & FREAD)) {
1708 kn->kn_fop = &pipe_nfiltops;
1709 return (0);
1710 }
1711 if ((kn->kn_filter == EVFILT_WRITE) && !(fp->f_flag & FWRITE)) {
1712 kn->kn_fop = &pipe_nfiltops;
1713 return (0);
1714 }
1715 cpipe = fp->f_data;
1716 PIPE_LOCK(cpipe);
1717 switch (kn->kn_filter) {
1718 case EVFILT_READ:
1719 kn->kn_fop = &pipe_rfiltops;
1720 break;
1721 case EVFILT_WRITE:
1722 kn->kn_fop = &pipe_wfiltops;
1723 if (cpipe->pipe_peer->pipe_present != PIPE_ACTIVE) {
1724 /* other end of pipe has been closed */
1725 PIPE_UNLOCK(cpipe);
1726 return (EPIPE);
1727 }
1728 cpipe = PIPE_PEER(cpipe);
1729 break;
1730 default:
1731 PIPE_UNLOCK(cpipe);
1732 return (EINVAL);
1733 }
1734
1735 kn->kn_hook = cpipe;
1736 knlist_add(&cpipe->pipe_sel.si_note, kn, 1);
1737 PIPE_UNLOCK(cpipe);
1738 return (0);
1739 }
1740
1741 static void
filt_pipedetach(struct knote * kn)1742 filt_pipedetach(struct knote *kn)
1743 {
1744 struct pipe *cpipe = kn->kn_hook;
1745
1746 PIPE_LOCK(cpipe);
1747 knlist_remove(&cpipe->pipe_sel.si_note, kn, 1);
1748 PIPE_UNLOCK(cpipe);
1749 }
1750
1751 /*ARGSUSED*/
1752 static int
filt_piperead(struct knote * kn,long hint)1753 filt_piperead(struct knote *kn, long hint)
1754 {
1755 struct file *fp = kn->kn_fp;
1756 struct pipe *rpipe = kn->kn_hook;
1757
1758 PIPE_LOCK_ASSERT(rpipe, MA_OWNED);
1759 kn->kn_data = rpipe->pipe_buffer.cnt;
1760 if (kn->kn_data == 0)
1761 kn->kn_data = rpipe->pipe_pages.cnt;
1762
1763 if ((rpipe->pipe_state & PIPE_EOF) != 0 &&
1764 ((rpipe->pipe_type & PIPE_TYPE_NAMED) == 0 ||
1765 fp->f_pipegen != rpipe->pipe_wgen)) {
1766 kn->kn_flags |= EV_EOF;
1767 return (1);
1768 }
1769 kn->kn_flags &= ~EV_EOF;
1770 return (kn->kn_data > 0);
1771 }
1772
1773 /*ARGSUSED*/
1774 static int
filt_pipewrite(struct knote * kn,long hint)1775 filt_pipewrite(struct knote *kn, long hint)
1776 {
1777 struct pipe *wpipe = kn->kn_hook;
1778
1779 /*
1780 * If this end of the pipe is closed, the knote was removed from the
1781 * knlist and the list lock (i.e., the pipe lock) is therefore not held.
1782 */
1783 if (wpipe->pipe_present == PIPE_ACTIVE ||
1784 (wpipe->pipe_type & PIPE_TYPE_NAMED) != 0) {
1785 PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
1786
1787 if (wpipe->pipe_state & PIPE_DIRECTW) {
1788 kn->kn_data = 0;
1789 } else if (wpipe->pipe_buffer.size > 0) {
1790 kn->kn_data = wpipe->pipe_buffer.size -
1791 wpipe->pipe_buffer.cnt;
1792 } else {
1793 kn->kn_data = PIPE_BUF;
1794 }
1795 }
1796
1797 if (wpipe->pipe_present != PIPE_ACTIVE ||
1798 (wpipe->pipe_state & PIPE_EOF)) {
1799 kn->kn_flags |= EV_EOF;
1800 return (1);
1801 }
1802 kn->kn_flags &= ~EV_EOF;
1803 return (kn->kn_data >= PIPE_BUF);
1804 }
1805
1806 static void
filt_pipedetach_notsup(struct knote * kn)1807 filt_pipedetach_notsup(struct knote *kn)
1808 {
1809
1810 }
1811
1812 static int
filt_pipenotsup(struct knote * kn,long hint)1813 filt_pipenotsup(struct knote *kn, long hint)
1814 {
1815
1816 return (0);
1817 }
1818