60#include <sys/param.h>
61#include <sys/fcntl.h>
62#include <sys/file.h>
63#include <sys/filedesc.h>
64#include <sys/fnv_hash.h>
65#include <sys/kernel.h>
66#include <sys/lock.h>
67#include <sys/malloc.h>
68#include <sys/mman.h>
69#include <sys/mutex.h>
70#include <sys/proc.h>
71#include <sys/refcount.h>
72#include <sys/resourcevar.h>
73#include <sys/stat.h>
74#include <sys/sysctl.h>
75#include <sys/sysproto.h>
76#include <sys/systm.h>
77#include <sys/sx.h>
78#include <sys/time.h>
79#include <sys/vnode.h>
80
81#include <security/mac/mac_framework.h>
82
83#include <vm/vm.h>
84#include <vm/vm_param.h>
85#include <vm/pmap.h>
86#include <vm/vm_map.h>
87#include <vm/vm_object.h>
88#include <vm/vm_page.h>
89#include <vm/vm_pager.h>
90#include <vm/swap_pager.h>
91
92struct shm_mapping {
93 char *sm_path;
94 Fnv32_t sm_fnv;
95 struct shmfd *sm_shmfd;
96 LIST_ENTRY(shm_mapping) sm_link;
97};
98
99static MALLOC_DEFINE(M_SHMFD, "shmfd", "shared memory file descriptor");
100static LIST_HEAD(, shm_mapping) *shm_dictionary;
101static struct sx shm_dict_lock;
102static struct mtx shm_timestamp_lock;
103static u_long shm_hash;
104
105#define SHM_HASH(fnv) (&shm_dictionary[(fnv) & shm_hash])
106
107static int shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags);
108static struct shmfd *shm_alloc(struct ucred *ucred, mode_t mode);
109static void shm_dict_init(void *arg);
110static void shm_drop(struct shmfd *shmfd);
111static struct shmfd *shm_hold(struct shmfd *shmfd);
112static void shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd);
113static struct shmfd *shm_lookup(char *path, Fnv32_t fnv);
114static int shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred);
115static void shm_dotruncate(struct shmfd *shmfd, off_t length);
116
117static fo_rdwr_t shm_read;
118static fo_rdwr_t shm_write;
119static fo_truncate_t shm_truncate;
120static fo_ioctl_t shm_ioctl;
121static fo_poll_t shm_poll;
122static fo_kqfilter_t shm_kqfilter;
123static fo_stat_t shm_stat;
124static fo_close_t shm_close;
125
126/* File descriptor operations. */
127static struct fileops shm_ops = {
128 .fo_read = shm_read,
129 .fo_write = shm_write,
130 .fo_truncate = shm_truncate,
131 .fo_ioctl = shm_ioctl,
132 .fo_poll = shm_poll,
133 .fo_kqfilter = shm_kqfilter,
134 .fo_stat = shm_stat,
135 .fo_close = shm_close,
136 .fo_flags = DFLAG_PASSABLE
137};
138
139FEATURE(posix_shm, "POSIX shared memory");
140
141static int
142shm_read(struct file *fp, struct uio *uio, struct ucred *active_cred,
143 int flags, struct thread *td)
144{
145
146 return (EOPNOTSUPP);
147}
148
149static int
150shm_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
151 int flags, struct thread *td)
152{
153
154 return (EOPNOTSUPP);
155}
156
157static int
158shm_truncate(struct file *fp, off_t length, struct ucred *active_cred,
159 struct thread *td)
160{
161 struct shmfd *shmfd;
162#ifdef MAC
163 int error;
164#endif
165
166 shmfd = fp->f_data;
167#ifdef MAC
168 error = mac_posixshm_check_truncate(active_cred, fp->f_cred, shmfd);
169 if (error)
170 return (error);
171#endif
172 shm_dotruncate(shmfd, length);
173 return (0);
174}
175
176static int
177shm_ioctl(struct file *fp, u_long com, void *data,
178 struct ucred *active_cred, struct thread *td)
179{
180
181 return (EOPNOTSUPP);
182}
183
184static int
185shm_poll(struct file *fp, int events, struct ucred *active_cred,
186 struct thread *td)
187{
188
189 return (EOPNOTSUPP);
190}
191
192static int
193shm_kqfilter(struct file *fp, struct knote *kn)
194{
195
196 return (EOPNOTSUPP);
197}
198
199static int
200shm_stat(struct file *fp, struct stat *sb, struct ucred *active_cred,
201 struct thread *td)
202{
203 struct shmfd *shmfd;
204#ifdef MAC
205 int error;
206#endif
207
208 shmfd = fp->f_data;
209
210#ifdef MAC
211 error = mac_posixshm_check_stat(active_cred, fp->f_cred, shmfd);
212 if (error)
213 return (error);
214#endif
215
216 /*
217 * Attempt to return sanish values for fstat() on a memory file
218 * descriptor.
219 */
220 bzero(sb, sizeof(*sb));
221 sb->st_mode = S_IFREG | shmfd->shm_mode; /* XXX */
222 sb->st_blksize = PAGE_SIZE;
223 sb->st_size = shmfd->shm_size;
224 sb->st_blocks = (sb->st_size + sb->st_blksize - 1) / sb->st_blksize;
225 sb->st_atimespec = shmfd->shm_atime;
226 sb->st_ctimespec = shmfd->shm_ctime;
227 sb->st_mtimespec = shmfd->shm_mtime;
228 sb->st_birthtimespec = shmfd->shm_birthtime;
229 sb->st_uid = shmfd->shm_uid;
230 sb->st_gid = shmfd->shm_gid;
231
232 return (0);
233}
234
235static int
236shm_close(struct file *fp, struct thread *td)
237{
238 struct shmfd *shmfd;
239
240 shmfd = fp->f_data;
241 fp->f_data = NULL;
242 shm_drop(shmfd);
243
244 return (0);
245}
246
247static void
248shm_dotruncate(struct shmfd *shmfd, off_t length)
249{
250 vm_object_t object;
251 vm_page_t m;
252 vm_pindex_t nobjsize;
253
254 object = shmfd->shm_object;
255 VM_OBJECT_LOCK(object);
256 if (length == shmfd->shm_size) {
257 VM_OBJECT_UNLOCK(object);
258 return;
259 }
260 nobjsize = OFF_TO_IDX(length + PAGE_MASK);
261
262 /* Are we shrinking? If so, trim the end. */
263 if (length < shmfd->shm_size) {
264 /* Toss in memory pages. */
265 if (nobjsize < object->size)
266 vm_object_page_remove(object, nobjsize, object->size,
267 FALSE);
268
269 /* Toss pages from swap. */
270 if (object->type == OBJT_SWAP)
271 swap_pager_freespace(object, nobjsize,
272 object->size - nobjsize);
273
274 /*
275 * If the last page is partially mapped, then zero out
276 * the garbage at the end of the page. See comments
277 * in vnode_pager_setsize() for more details.
278 *
279 * XXXJHB: This handles in memory pages, but what about
280 * a page swapped out to disk?
281 */
282 if ((length & PAGE_MASK) &&
283 (m = vm_page_lookup(object, OFF_TO_IDX(length))) != NULL &&
284 m->valid != 0) {
285 int base = (int)length & PAGE_MASK;
286 int size = PAGE_SIZE - base;
287
288 pmap_zero_page_area(m, base, size);
289
290 /*
291 * Update the valid bits to reflect the blocks that
292 * have been zeroed. Some of these valid bits may
293 * have already been set.
294 */
295 vm_page_set_valid(m, base, size);
296
297 /*
298 * Round "base" to the next block boundary so that the
299 * dirty bit for a partially zeroed block is not
300 * cleared.
301 */
302 base = roundup2(base, DEV_BSIZE);
303
304 vm_page_lock_queues();
305 vm_page_clear_dirty(m, base, PAGE_SIZE - base);
306 vm_page_unlock_queues();
307 } else if ((length & PAGE_MASK) &&
308 __predict_false(object->cache != NULL)) {
309 vm_page_cache_free(object, OFF_TO_IDX(length),
310 nobjsize);
311 }
312 }
313 shmfd->shm_size = length;
314 mtx_lock(&shm_timestamp_lock);
315 vfs_timestamp(&shmfd->shm_ctime);
316 shmfd->shm_mtime = shmfd->shm_ctime;
317 mtx_unlock(&shm_timestamp_lock);
318 object->size = nobjsize;
319 VM_OBJECT_UNLOCK(object);
320}
321
322/*
323 * shmfd object management including creation and reference counting
324 * routines.
325 */
326static struct shmfd *
327shm_alloc(struct ucred *ucred, mode_t mode)
328{
329 struct shmfd *shmfd;
330
331 shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO);
332 shmfd->shm_size = 0;
333 shmfd->shm_uid = ucred->cr_uid;
334 shmfd->shm_gid = ucred->cr_gid;
335 shmfd->shm_mode = mode;
336 shmfd->shm_object = vm_pager_allocate(OBJT_DEFAULT, NULL,
337 shmfd->shm_size, VM_PROT_DEFAULT, 0);
338 KASSERT(shmfd->shm_object != NULL, ("shm_create: vm_pager_allocate"));
339 VM_OBJECT_LOCK(shmfd->shm_object);
340 vm_object_clear_flag(shmfd->shm_object, OBJ_ONEMAPPING);
341 vm_object_set_flag(shmfd->shm_object, OBJ_NOSPLIT);
342 VM_OBJECT_UNLOCK(shmfd->shm_object);
343 vfs_timestamp(&shmfd->shm_birthtime);
344 shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime =
345 shmfd->shm_birthtime;
346 refcount_init(&shmfd->shm_refs, 1);
347#ifdef MAC
348 mac_posixshm_init(shmfd);
349 mac_posixshm_create(ucred, shmfd);
350#endif
351
352 return (shmfd);
353}
354
355static struct shmfd *
356shm_hold(struct shmfd *shmfd)
357{
358
359 refcount_acquire(&shmfd->shm_refs);
360 return (shmfd);
361}
362
363static void
364shm_drop(struct shmfd *shmfd)
365{
366
367 if (refcount_release(&shmfd->shm_refs)) {
368#ifdef MAC
369 mac_posixshm_destroy(shmfd);
370#endif
371 vm_object_deallocate(shmfd->shm_object);
372 free(shmfd, M_SHMFD);
373 }
374}
375
376/*
377 * Determine if the credentials have sufficient permissions for a
378 * specified combination of FREAD and FWRITE.
379 */
380static int
381shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags)
382{
383 accmode_t accmode;
384
385 accmode = 0;
386 if (flags & FREAD)
387 accmode |= VREAD;
388 if (flags & FWRITE)
389 accmode |= VWRITE;
390 return (vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid,
391 accmode, ucred, NULL));
392}
393
394/*
395 * Dictionary management. We maintain an in-kernel dictionary to map
396 * paths to shmfd objects. We use the FNV hash on the path to store
397 * the mappings in a hash table.
398 */
399static void
400shm_dict_init(void *arg)
401{
402
403 mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF);
404 sx_init(&shm_dict_lock, "shm dictionary");
405 shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash);
406}
407SYSINIT(shm_dict_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_dict_init, NULL);
408
409static struct shmfd *
410shm_lookup(char *path, Fnv32_t fnv)
411{
412 struct shm_mapping *map;
413
414 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) {
415 if (map->sm_fnv != fnv)
416 continue;
417 if (strcmp(map->sm_path, path) == 0)
418 return (map->sm_shmfd);
419 }
420
421 return (NULL);
422}
423
424static void
425shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd)
426{
427 struct shm_mapping *map;
428
429 map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK);
430 map->sm_path = path;
431 map->sm_fnv = fnv;
432 map->sm_shmfd = shm_hold(shmfd);
433 LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link);
434}
435
436static int
437shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred)
438{
439 struct shm_mapping *map;
440 int error;
441
442 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) {
443 if (map->sm_fnv != fnv)
444 continue;
445 if (strcmp(map->sm_path, path) == 0) {
446#ifdef MAC
447 error = mac_posixshm_check_unlink(ucred, map->sm_shmfd);
448 if (error)
449 return (error);
450#endif
451 error = shm_access(map->sm_shmfd, ucred,
452 FREAD | FWRITE);
453 if (error)
454 return (error);
455 LIST_REMOVE(map, sm_link);
456 shm_drop(map->sm_shmfd);
457 free(map->sm_path, M_SHMFD);
458 free(map, M_SHMFD);
459 return (0);
460 }
461 }
462
463 return (ENOENT);
464}
465
466/* System calls. */
467int
468shm_open(struct thread *td, struct shm_open_args *uap)
469{
470 struct filedesc *fdp;
471 struct shmfd *shmfd;
472 struct file *fp;
473 char *path;
474 Fnv32_t fnv;
475 mode_t cmode;
476 int fd, error;
477
478 if ((uap->flags & O_ACCMODE) != O_RDONLY &&
479 (uap->flags & O_ACCMODE) != O_RDWR)
480 return (EINVAL);
481
482 if ((uap->flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC)) != 0)
483 return (EINVAL);
484
485 fdp = td->td_proc->p_fd;
486 cmode = (uap->mode & ~fdp->fd_cmask) & ACCESSPERMS;
487
488 error = falloc(td, &fp, &fd);
489 if (error)
490 return (error);
491
492 /* A SHM_ANON path pointer creates an anonymous object. */
493 if (uap->path == SHM_ANON) {
494 /* A read-only anonymous object is pointless. */
495 if ((uap->flags & O_ACCMODE) == O_RDONLY) {
496 fdclose(fdp, fp, fd, td);
497 fdrop(fp, td);
498 return (EINVAL);
499 }
500 shmfd = shm_alloc(td->td_ucred, cmode);
501 } else {
502 path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK);
503 error = copyinstr(uap->path, path, MAXPATHLEN, NULL);
504
505 /* Require paths to start with a '/' character. */
506 if (error == 0 && path[0] != '/')
507 error = EINVAL;
508 if (error) {
509 fdclose(fdp, fp, fd, td);
510 fdrop(fp, td);
511 free(path, M_SHMFD);
512 return (error);
513 }
514
515 fnv = fnv_32_str(path, FNV1_32_INIT);
516 sx_xlock(&shm_dict_lock);
517 shmfd = shm_lookup(path, fnv);
518 if (shmfd == NULL) {
519 /* Object does not yet exist, create it if requested. */
520 if (uap->flags & O_CREAT) {
521 shmfd = shm_alloc(td->td_ucred, cmode);
522 shm_insert(path, fnv, shmfd);
523 } else {
524 free(path, M_SHMFD);
525 error = ENOENT;
526 }
527 } else {
528 /*
529 * Object already exists, obtain a new
530 * reference if requested and permitted.
531 */
532 free(path, M_SHMFD);
533 if ((uap->flags & (O_CREAT | O_EXCL)) ==
534 (O_CREAT | O_EXCL))
535 error = EEXIST;
536 else {
537#ifdef MAC
538 error = mac_posixshm_check_open(td->td_ucred,
539 shmfd);
540 if (error == 0)
541#endif
542 error = shm_access(shmfd, td->td_ucred,
543 FFLAGS(uap->flags & O_ACCMODE));
544 }
545
546 /*
547 * Truncate the file back to zero length if
548 * O_TRUNC was specified and the object was
549 * opened with read/write.
550 */
551 if (error == 0 &&
552 (uap->flags & (O_ACCMODE | O_TRUNC)) ==
553 (O_RDWR | O_TRUNC)) {
554#ifdef MAC
555 error = mac_posixshm_check_truncate(
556 td->td_ucred, fp->f_cred, shmfd);
557 if (error == 0)
558#endif
559 shm_dotruncate(shmfd, 0);
560 }
561 if (error == 0)
562 shm_hold(shmfd);
563 }
564 sx_xunlock(&shm_dict_lock);
565
566 if (error) {
567 fdclose(fdp, fp, fd, td);
568 fdrop(fp, td);
569 return (error);
570 }
571 }
572
573 finit(fp, FFLAGS(uap->flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops);
574
575 FILEDESC_XLOCK(fdp);
576 if (fdp->fd_ofiles[fd] == fp)
577 fdp->fd_ofileflags[fd] |= UF_EXCLOSE;
578 FILEDESC_XUNLOCK(fdp);
579 td->td_retval[0] = fd;
580 fdrop(fp, td);
581
582 return (0);
583}
584
585int
586shm_unlink(struct thread *td, struct shm_unlink_args *uap)
587{
588 char *path;
589 Fnv32_t fnv;
590 int error;
591
592 path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
593 error = copyinstr(uap->path, path, MAXPATHLEN, NULL);
594 if (error) {
595 free(path, M_TEMP);
596 return (error);
597 }
598
599 fnv = fnv_32_str(path, FNV1_32_INIT);
600 sx_xlock(&shm_dict_lock);
601 error = shm_remove(path, fnv, td->td_ucred);
602 sx_xunlock(&shm_dict_lock);
603 free(path, M_TEMP);
604
605 return (error);
606}
607
608/*
609 * mmap() helper to validate mmap() requests against shm object state
610 * and give mmap() the vm_object to use for the mapping.
611 */
612int
613shm_mmap(struct shmfd *shmfd, vm_size_t objsize, vm_ooffset_t foff,
614 vm_object_t *obj)
615{
616
617 /*
618 * XXXRW: This validation is probably insufficient, and subject to
619 * sign errors. It should be fixed.
620 */
621 if (foff >= shmfd->shm_size ||
622 foff + objsize > round_page(shmfd->shm_size))
623 return (EINVAL);
624
625 mtx_lock(&shm_timestamp_lock);
626 vfs_timestamp(&shmfd->shm_atime);
627 mtx_unlock(&shm_timestamp_lock);
628 vm_object_reference(shmfd->shm_object);
629 *obj = shmfd->shm_object;
630 return (0);
631}
| 58#include <sys/param.h>
59#include <sys/fcntl.h>
60#include <sys/file.h>
61#include <sys/filedesc.h>
62#include <sys/fnv_hash.h>
63#include <sys/kernel.h>
64#include <sys/lock.h>
65#include <sys/malloc.h>
66#include <sys/mman.h>
67#include <sys/mutex.h>
68#include <sys/proc.h>
69#include <sys/refcount.h>
70#include <sys/resourcevar.h>
71#include <sys/stat.h>
72#include <sys/sysctl.h>
73#include <sys/sysproto.h>
74#include <sys/systm.h>
75#include <sys/sx.h>
76#include <sys/time.h>
77#include <sys/vnode.h>
78
79#include <security/mac/mac_framework.h>
80
81#include <vm/vm.h>
82#include <vm/vm_param.h>
83#include <vm/pmap.h>
84#include <vm/vm_map.h>
85#include <vm/vm_object.h>
86#include <vm/vm_page.h>
87#include <vm/vm_pager.h>
88#include <vm/swap_pager.h>
89
90struct shm_mapping {
91 char *sm_path;
92 Fnv32_t sm_fnv;
93 struct shmfd *sm_shmfd;
94 LIST_ENTRY(shm_mapping) sm_link;
95};
96
97static MALLOC_DEFINE(M_SHMFD, "shmfd", "shared memory file descriptor");
98static LIST_HEAD(, shm_mapping) *shm_dictionary;
99static struct sx shm_dict_lock;
100static struct mtx shm_timestamp_lock;
101static u_long shm_hash;
102
103#define SHM_HASH(fnv) (&shm_dictionary[(fnv) & shm_hash])
104
105static int shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags);
106static struct shmfd *shm_alloc(struct ucred *ucred, mode_t mode);
107static void shm_dict_init(void *arg);
108static void shm_drop(struct shmfd *shmfd);
109static struct shmfd *shm_hold(struct shmfd *shmfd);
110static void shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd);
111static struct shmfd *shm_lookup(char *path, Fnv32_t fnv);
112static int shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred);
113static void shm_dotruncate(struct shmfd *shmfd, off_t length);
114
115static fo_rdwr_t shm_read;
116static fo_rdwr_t shm_write;
117static fo_truncate_t shm_truncate;
118static fo_ioctl_t shm_ioctl;
119static fo_poll_t shm_poll;
120static fo_kqfilter_t shm_kqfilter;
121static fo_stat_t shm_stat;
122static fo_close_t shm_close;
123
124/* File descriptor operations. */
125static struct fileops shm_ops = {
126 .fo_read = shm_read,
127 .fo_write = shm_write,
128 .fo_truncate = shm_truncate,
129 .fo_ioctl = shm_ioctl,
130 .fo_poll = shm_poll,
131 .fo_kqfilter = shm_kqfilter,
132 .fo_stat = shm_stat,
133 .fo_close = shm_close,
134 .fo_flags = DFLAG_PASSABLE
135};
136
137FEATURE(posix_shm, "POSIX shared memory");
138
139static int
140shm_read(struct file *fp, struct uio *uio, struct ucred *active_cred,
141 int flags, struct thread *td)
142{
143
144 return (EOPNOTSUPP);
145}
146
147static int
148shm_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
149 int flags, struct thread *td)
150{
151
152 return (EOPNOTSUPP);
153}
154
155static int
156shm_truncate(struct file *fp, off_t length, struct ucred *active_cred,
157 struct thread *td)
158{
159 struct shmfd *shmfd;
160#ifdef MAC
161 int error;
162#endif
163
164 shmfd = fp->f_data;
165#ifdef MAC
166 error = mac_posixshm_check_truncate(active_cred, fp->f_cred, shmfd);
167 if (error)
168 return (error);
169#endif
170 shm_dotruncate(shmfd, length);
171 return (0);
172}
173
174static int
175shm_ioctl(struct file *fp, u_long com, void *data,
176 struct ucred *active_cred, struct thread *td)
177{
178
179 return (EOPNOTSUPP);
180}
181
182static int
183shm_poll(struct file *fp, int events, struct ucred *active_cred,
184 struct thread *td)
185{
186
187 return (EOPNOTSUPP);
188}
189
190static int
191shm_kqfilter(struct file *fp, struct knote *kn)
192{
193
194 return (EOPNOTSUPP);
195}
196
197static int
198shm_stat(struct file *fp, struct stat *sb, struct ucred *active_cred,
199 struct thread *td)
200{
201 struct shmfd *shmfd;
202#ifdef MAC
203 int error;
204#endif
205
206 shmfd = fp->f_data;
207
208#ifdef MAC
209 error = mac_posixshm_check_stat(active_cred, fp->f_cred, shmfd);
210 if (error)
211 return (error);
212#endif
213
214 /*
215 * Attempt to return sanish values for fstat() on a memory file
216 * descriptor.
217 */
218 bzero(sb, sizeof(*sb));
219 sb->st_mode = S_IFREG | shmfd->shm_mode; /* XXX */
220 sb->st_blksize = PAGE_SIZE;
221 sb->st_size = shmfd->shm_size;
222 sb->st_blocks = (sb->st_size + sb->st_blksize - 1) / sb->st_blksize;
223 sb->st_atimespec = shmfd->shm_atime;
224 sb->st_ctimespec = shmfd->shm_ctime;
225 sb->st_mtimespec = shmfd->shm_mtime;
226 sb->st_birthtimespec = shmfd->shm_birthtime;
227 sb->st_uid = shmfd->shm_uid;
228 sb->st_gid = shmfd->shm_gid;
229
230 return (0);
231}
232
233static int
234shm_close(struct file *fp, struct thread *td)
235{
236 struct shmfd *shmfd;
237
238 shmfd = fp->f_data;
239 fp->f_data = NULL;
240 shm_drop(shmfd);
241
242 return (0);
243}
244
245static void
246shm_dotruncate(struct shmfd *shmfd, off_t length)
247{
248 vm_object_t object;
249 vm_page_t m;
250 vm_pindex_t nobjsize;
251
252 object = shmfd->shm_object;
253 VM_OBJECT_LOCK(object);
254 if (length == shmfd->shm_size) {
255 VM_OBJECT_UNLOCK(object);
256 return;
257 }
258 nobjsize = OFF_TO_IDX(length + PAGE_MASK);
259
260 /* Are we shrinking? If so, trim the end. */
261 if (length < shmfd->shm_size) {
262 /* Toss in memory pages. */
263 if (nobjsize < object->size)
264 vm_object_page_remove(object, nobjsize, object->size,
265 FALSE);
266
267 /* Toss pages from swap. */
268 if (object->type == OBJT_SWAP)
269 swap_pager_freespace(object, nobjsize,
270 object->size - nobjsize);
271
272 /*
273 * If the last page is partially mapped, then zero out
274 * the garbage at the end of the page. See comments
275 * in vnode_pager_setsize() for more details.
276 *
277 * XXXJHB: This handles in memory pages, but what about
278 * a page swapped out to disk?
279 */
280 if ((length & PAGE_MASK) &&
281 (m = vm_page_lookup(object, OFF_TO_IDX(length))) != NULL &&
282 m->valid != 0) {
283 int base = (int)length & PAGE_MASK;
284 int size = PAGE_SIZE - base;
285
286 pmap_zero_page_area(m, base, size);
287
288 /*
289 * Update the valid bits to reflect the blocks that
290 * have been zeroed. Some of these valid bits may
291 * have already been set.
292 */
293 vm_page_set_valid(m, base, size);
294
295 /*
296 * Round "base" to the next block boundary so that the
297 * dirty bit for a partially zeroed block is not
298 * cleared.
299 */
300 base = roundup2(base, DEV_BSIZE);
301
302 vm_page_lock_queues();
303 vm_page_clear_dirty(m, base, PAGE_SIZE - base);
304 vm_page_unlock_queues();
305 } else if ((length & PAGE_MASK) &&
306 __predict_false(object->cache != NULL)) {
307 vm_page_cache_free(object, OFF_TO_IDX(length),
308 nobjsize);
309 }
310 }
311 shmfd->shm_size = length;
312 mtx_lock(&shm_timestamp_lock);
313 vfs_timestamp(&shmfd->shm_ctime);
314 shmfd->shm_mtime = shmfd->shm_ctime;
315 mtx_unlock(&shm_timestamp_lock);
316 object->size = nobjsize;
317 VM_OBJECT_UNLOCK(object);
318}
319
320/*
321 * shmfd object management including creation and reference counting
322 * routines.
323 */
324static struct shmfd *
325shm_alloc(struct ucred *ucred, mode_t mode)
326{
327 struct shmfd *shmfd;
328
329 shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO);
330 shmfd->shm_size = 0;
331 shmfd->shm_uid = ucred->cr_uid;
332 shmfd->shm_gid = ucred->cr_gid;
333 shmfd->shm_mode = mode;
334 shmfd->shm_object = vm_pager_allocate(OBJT_DEFAULT, NULL,
335 shmfd->shm_size, VM_PROT_DEFAULT, 0);
336 KASSERT(shmfd->shm_object != NULL, ("shm_create: vm_pager_allocate"));
337 VM_OBJECT_LOCK(shmfd->shm_object);
338 vm_object_clear_flag(shmfd->shm_object, OBJ_ONEMAPPING);
339 vm_object_set_flag(shmfd->shm_object, OBJ_NOSPLIT);
340 VM_OBJECT_UNLOCK(shmfd->shm_object);
341 vfs_timestamp(&shmfd->shm_birthtime);
342 shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime =
343 shmfd->shm_birthtime;
344 refcount_init(&shmfd->shm_refs, 1);
345#ifdef MAC
346 mac_posixshm_init(shmfd);
347 mac_posixshm_create(ucred, shmfd);
348#endif
349
350 return (shmfd);
351}
352
353static struct shmfd *
354shm_hold(struct shmfd *shmfd)
355{
356
357 refcount_acquire(&shmfd->shm_refs);
358 return (shmfd);
359}
360
361static void
362shm_drop(struct shmfd *shmfd)
363{
364
365 if (refcount_release(&shmfd->shm_refs)) {
366#ifdef MAC
367 mac_posixshm_destroy(shmfd);
368#endif
369 vm_object_deallocate(shmfd->shm_object);
370 free(shmfd, M_SHMFD);
371 }
372}
373
374/*
375 * Determine if the credentials have sufficient permissions for a
376 * specified combination of FREAD and FWRITE.
377 */
378static int
379shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags)
380{
381 accmode_t accmode;
382
383 accmode = 0;
384 if (flags & FREAD)
385 accmode |= VREAD;
386 if (flags & FWRITE)
387 accmode |= VWRITE;
388 return (vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid,
389 accmode, ucred, NULL));
390}
391
392/*
393 * Dictionary management. We maintain an in-kernel dictionary to map
394 * paths to shmfd objects. We use the FNV hash on the path to store
395 * the mappings in a hash table.
396 */
397static void
398shm_dict_init(void *arg)
399{
400
401 mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF);
402 sx_init(&shm_dict_lock, "shm dictionary");
403 shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash);
404}
405SYSINIT(shm_dict_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_dict_init, NULL);
406
407static struct shmfd *
408shm_lookup(char *path, Fnv32_t fnv)
409{
410 struct shm_mapping *map;
411
412 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) {
413 if (map->sm_fnv != fnv)
414 continue;
415 if (strcmp(map->sm_path, path) == 0)
416 return (map->sm_shmfd);
417 }
418
419 return (NULL);
420}
421
422static void
423shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd)
424{
425 struct shm_mapping *map;
426
427 map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK);
428 map->sm_path = path;
429 map->sm_fnv = fnv;
430 map->sm_shmfd = shm_hold(shmfd);
431 LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link);
432}
433
434static int
435shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred)
436{
437 struct shm_mapping *map;
438 int error;
439
440 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) {
441 if (map->sm_fnv != fnv)
442 continue;
443 if (strcmp(map->sm_path, path) == 0) {
444#ifdef MAC
445 error = mac_posixshm_check_unlink(ucred, map->sm_shmfd);
446 if (error)
447 return (error);
448#endif
449 error = shm_access(map->sm_shmfd, ucred,
450 FREAD | FWRITE);
451 if (error)
452 return (error);
453 LIST_REMOVE(map, sm_link);
454 shm_drop(map->sm_shmfd);
455 free(map->sm_path, M_SHMFD);
456 free(map, M_SHMFD);
457 return (0);
458 }
459 }
460
461 return (ENOENT);
462}
463
464/* System calls. */
465int
466shm_open(struct thread *td, struct shm_open_args *uap)
467{
468 struct filedesc *fdp;
469 struct shmfd *shmfd;
470 struct file *fp;
471 char *path;
472 Fnv32_t fnv;
473 mode_t cmode;
474 int fd, error;
475
476 if ((uap->flags & O_ACCMODE) != O_RDONLY &&
477 (uap->flags & O_ACCMODE) != O_RDWR)
478 return (EINVAL);
479
480 if ((uap->flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC)) != 0)
481 return (EINVAL);
482
483 fdp = td->td_proc->p_fd;
484 cmode = (uap->mode & ~fdp->fd_cmask) & ACCESSPERMS;
485
486 error = falloc(td, &fp, &fd);
487 if (error)
488 return (error);
489
490 /* A SHM_ANON path pointer creates an anonymous object. */
491 if (uap->path == SHM_ANON) {
492 /* A read-only anonymous object is pointless. */
493 if ((uap->flags & O_ACCMODE) == O_RDONLY) {
494 fdclose(fdp, fp, fd, td);
495 fdrop(fp, td);
496 return (EINVAL);
497 }
498 shmfd = shm_alloc(td->td_ucred, cmode);
499 } else {
500 path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK);
501 error = copyinstr(uap->path, path, MAXPATHLEN, NULL);
502
503 /* Require paths to start with a '/' character. */
504 if (error == 0 && path[0] != '/')
505 error = EINVAL;
506 if (error) {
507 fdclose(fdp, fp, fd, td);
508 fdrop(fp, td);
509 free(path, M_SHMFD);
510 return (error);
511 }
512
513 fnv = fnv_32_str(path, FNV1_32_INIT);
514 sx_xlock(&shm_dict_lock);
515 shmfd = shm_lookup(path, fnv);
516 if (shmfd == NULL) {
517 /* Object does not yet exist, create it if requested. */
518 if (uap->flags & O_CREAT) {
519 shmfd = shm_alloc(td->td_ucred, cmode);
520 shm_insert(path, fnv, shmfd);
521 } else {
522 free(path, M_SHMFD);
523 error = ENOENT;
524 }
525 } else {
526 /*
527 * Object already exists, obtain a new
528 * reference if requested and permitted.
529 */
530 free(path, M_SHMFD);
531 if ((uap->flags & (O_CREAT | O_EXCL)) ==
532 (O_CREAT | O_EXCL))
533 error = EEXIST;
534 else {
535#ifdef MAC
536 error = mac_posixshm_check_open(td->td_ucred,
537 shmfd);
538 if (error == 0)
539#endif
540 error = shm_access(shmfd, td->td_ucred,
541 FFLAGS(uap->flags & O_ACCMODE));
542 }
543
544 /*
545 * Truncate the file back to zero length if
546 * O_TRUNC was specified and the object was
547 * opened with read/write.
548 */
549 if (error == 0 &&
550 (uap->flags & (O_ACCMODE | O_TRUNC)) ==
551 (O_RDWR | O_TRUNC)) {
552#ifdef MAC
553 error = mac_posixshm_check_truncate(
554 td->td_ucred, fp->f_cred, shmfd);
555 if (error == 0)
556#endif
557 shm_dotruncate(shmfd, 0);
558 }
559 if (error == 0)
560 shm_hold(shmfd);
561 }
562 sx_xunlock(&shm_dict_lock);
563
564 if (error) {
565 fdclose(fdp, fp, fd, td);
566 fdrop(fp, td);
567 return (error);
568 }
569 }
570
571 finit(fp, FFLAGS(uap->flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops);
572
573 FILEDESC_XLOCK(fdp);
574 if (fdp->fd_ofiles[fd] == fp)
575 fdp->fd_ofileflags[fd] |= UF_EXCLOSE;
576 FILEDESC_XUNLOCK(fdp);
577 td->td_retval[0] = fd;
578 fdrop(fp, td);
579
580 return (0);
581}
582
583int
584shm_unlink(struct thread *td, struct shm_unlink_args *uap)
585{
586 char *path;
587 Fnv32_t fnv;
588 int error;
589
590 path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
591 error = copyinstr(uap->path, path, MAXPATHLEN, NULL);
592 if (error) {
593 free(path, M_TEMP);
594 return (error);
595 }
596
597 fnv = fnv_32_str(path, FNV1_32_INIT);
598 sx_xlock(&shm_dict_lock);
599 error = shm_remove(path, fnv, td->td_ucred);
600 sx_xunlock(&shm_dict_lock);
601 free(path, M_TEMP);
602
603 return (error);
604}
605
606/*
607 * mmap() helper to validate mmap() requests against shm object state
608 * and give mmap() the vm_object to use for the mapping.
609 */
610int
611shm_mmap(struct shmfd *shmfd, vm_size_t objsize, vm_ooffset_t foff,
612 vm_object_t *obj)
613{
614
615 /*
616 * XXXRW: This validation is probably insufficient, and subject to
617 * sign errors. It should be fixed.
618 */
619 if (foff >= shmfd->shm_size ||
620 foff + objsize > round_page(shmfd->shm_size))
621 return (EINVAL);
622
623 mtx_lock(&shm_timestamp_lock);
624 vfs_timestamp(&shmfd->shm_atime);
625 mtx_unlock(&shm_timestamp_lock);
626 vm_object_reference(shmfd->shm_object);
627 *obj = shmfd->shm_object;
628 return (0);
629}
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