sysv_shm.c revision 1.24 
1/*	$NetBSD: sysv_shm.c,v 1.24 1994/08/22 23:37:17 deraadt Exp $	*/
2
3/*
4 * Copyright (c) 1994 Adam Glass and Charles Hannum.  All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 * 3. All advertising materials mentioning features or use of this software
15 *    must display the following acknowledgement:
16 *	This product includes software developed by Adam Glass and Charles
17 *	Hannum.
18 * 4. The names of the authors may not be used to endorse or promote products
19 *    derived from this software without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
22 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
23 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
24 * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT,
25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
26 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
30 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31 */
32
33#include <sys/types.h>
34#include <sys/param.h>
35#include <sys/kernel.h>
36#include <sys/shm.h>
37#include <sys/proc.h>
38#include <sys/uio.h>
39#include <sys/time.h>
40#include <sys/malloc.h>
41#include <sys/mman.h>
42#include <sys/systm.h>
43#include <sys/stat.h>
44
45#include <vm/vm.h>
46#include <vm/vm_map.h>
47#include <vm/vm_map.h>
48#include <vm/vm_kern.h>
49
50/*
51 * Provides the following externally accessible functions:
52 *
53 * shminit(void);		           initialization
54 * shmexit(struct proc *)                  cleanup
55 * shmfork(struct proc *, struct proc *, int) fork handling
56 * shmsys(arg1, arg2, arg3, arg4);         shm{at,ctl,dt,get}(arg2, arg3, arg4)
57 *
58 * Structures:
59 * shmsegs (an array of 'struct shmid_ds')
60 * per proc array of 'struct shmmap_state'
61 */
62
63int	shmat(), shmctl(), shmdt(), shmget();
64int	(*shmcalls[])() = { shmat, shmctl, shmdt, shmget };
65
66#define	SHMSEG_FREE     	0x0200
67#define	SHMSEG_REMOVED  	0x0400
68#define	SHMSEG_ALLOCATED	0x0800
69#define	SHMSEG_WANTED		0x1000
70
71vm_map_t sysvshm_map;
72int shm_last_free, shm_nused, shm_committed;
73
74struct shm_handle {
75	vm_offset_t kva;
76};
77
78struct shmmap_state {
79	vm_offset_t va;
80	int shmid;
81};
82
83static void shm_deallocate_segment __P((struct shmid_ds *));
84static int shm_find_segment_by_key __P((key_t));
85static struct shmid_ds *shm_find_segment_by_shmid __P((int));
86static int shm_delete_mapping __P((struct proc *, struct shmmap_state *));
87
88static int
89shm_find_segment_by_key(key)
90	key_t key;
91{
92	int i;
93
94	for (i = 0; i < shminfo.shmmni; i++)
95		if ((shmsegs[i].shm_perm.mode & SHMSEG_ALLOCATED) &&
96		    shmsegs[i].shm_perm.key == key)
97			return i;
98	return -1;
99}
100
101static struct shmid_ds *
102shm_find_segment_by_shmid(shmid)
103	int shmid;
104{
105	int segnum;
106	struct shmid_ds *shmseg;
107
108	segnum = IPCID_TO_IX(shmid);
109	if (segnum < 0 || segnum >= shminfo.shmmni)
110		return NULL;
111	shmseg = &shmsegs[segnum];
112	if ((shmseg->shm_perm.mode & (SHMSEG_ALLOCATED | SHMSEG_REMOVED))
113	    != SHMSEG_ALLOCATED ||
114	    shmseg->shm_perm.seq != IPCID_TO_SEQ(shmid))
115		return NULL;
116	return shmseg;
117}
118
119static void
120shm_deallocate_segment(shmseg)
121	struct shmid_ds *shmseg;
122{
123	struct shm_handle *shm_handle;
124	size_t size;
125
126	shm_handle = shmseg->shm_internal;
127	size = (shmseg->shm_segsz + CLOFSET) & ~CLOFSET;
128	vm_deallocate(sysvshm_map, shm_handle->kva, size);
129	free((caddr_t)shm_handle, M_SHM);
130	shmseg->shm_internal = NULL;
131	shm_committed -= btoc(size);
132	shmseg->shm_perm.mode = SHMSEG_FREE;
133}
134
135static int
136shm_delete_mapping(p, shmmap_s)
137	struct proc *p;
138	struct shmmap_state *shmmap_s;
139{
140	struct shmid_ds *shmseg;
141	int segnum, result;
142	size_t size;
143
144	segnum = IPCID_TO_IX(shmmap_s->shmid);
145	shmseg = &shmsegs[segnum];
146	size = (shmseg->shm_segsz + CLOFSET) & ~CLOFSET;
147	result = vm_deallocate(&p->p_vmspace->vm_map, shmmap_s->va, size);
148	if (result != KERN_SUCCESS)
149		return EINVAL;
150	shmmap_s->shmid = -1;
151	shmseg->shm_dtime = time.tv_sec;
152	if ((--shmseg->shm_nattch <= 0) &&
153	    (shmseg->shm_perm.mode & SHMSEG_REMOVED)) {
154		shm_deallocate_segment(shmseg);
155		shm_last_free = segnum;
156	}
157	return 0;
158}
159
160struct shmdt_args {
161	void *shmaddr;
162};
163int
164shmdt(p, uap, retval)
165	struct proc *p;
166	struct shmdt_args *uap;
167	int *retval;
168{
169	struct shmmap_state *shmmap_s;
170	int i;
171
172	shmmap_s = (struct shmmap_state *)p->p_vmspace->vm_shm;
173	for (i = 0; i < shminfo.shmseg; i++, shmmap_s++)
174		if (shmmap_s->shmid != -1 &&
175		    shmmap_s->va == (vm_offset_t)uap->shmaddr)
176			break;
177	if (i == shminfo.shmseg)
178		return EINVAL;
179	return shm_delete_mapping(p, shmmap_s);
180}
181
182struct shmat_args {
183	int shmid;
184	void *shmaddr;
185	int shmflg;
186};
187int
188shmat(p, uap, retval)
189	struct proc *p;
190	struct shmat_args *uap;
191	int *retval;
192{
193	int error, i, flags;
194	struct ucred *cred = p->p_ucred;
195	struct shmid_ds *shmseg;
196	struct shmmap_state *shmmap_s = NULL;
197	vm_offset_t attach_va;
198	vm_prot_t prot;
199	vm_size_t size;
200
201	shmmap_s = (struct shmmap_state *)p->p_vmspace->vm_shm;
202	if (shmmap_s == NULL) {
203		size = shminfo.shmseg * sizeof(struct shmmap_state);
204		shmmap_s = malloc(size, M_SHM, M_WAITOK);
205		for (i = 0; i < shminfo.shmseg; i++)
206			shmmap_s[i].shmid = -1;
207		p->p_vmspace->vm_shm = (caddr_t)shmmap_s;
208	}
209	shmseg = shm_find_segment_by_shmid(uap->shmid);
210	if (shmseg == NULL)
211		return EINVAL;
212	if (error = ipcperm(cred, &shmseg->shm_perm,
213	    (uap->shmflg & SHM_RDONLY) ? IPC_R : IPC_R|IPC_W))
214		return error;
215	for (i = 0; i < shminfo.shmseg; i++) {
216		if (shmmap_s->shmid == -1)
217			break;
218		shmmap_s++;
219	}
220	if (i >= shminfo.shmseg)
221		return EMFILE;
222	size = (shmseg->shm_segsz + CLOFSET) & ~CLOFSET;
223	prot = VM_PROT_READ;
224	if ((uap->shmflg & SHM_RDONLY) == 0)
225		prot |= VM_PROT_WRITE;
226	flags = MAP_ANON | MAP_SHARED;
227	if (uap->shmaddr) {
228		flags |= MAP_FIXED;
229		if (uap->shmflg & SHM_RND)
230			attach_va = (vm_offset_t)uap->shmaddr & ~(SHMLBA-1);
231		else if (((vm_offset_t)uap->shmaddr & (SHMLBA-1)) == 0)
232			attach_va = (vm_offset_t)uap->shmaddr;
233		else
234			return EINVAL;
235	} else {
236		/* This is just a hint to vm_mmap() about where to put it. */
237		attach_va = round_page(p->p_vmspace->vm_daddr + MAXDSIZ);
238	}
239	error = vm_mmap(&p->p_vmspace->vm_map, &attach_va, size, prot,
240	    VM_PROT_DEFAULT, flags, (caddr_t) uap->shmid, 0);
241	if (error)
242		return error;
243	shmmap_s->va = attach_va;
244	shmmap_s->shmid = uap->shmid;
245	shmseg->shm_lpid = p->p_pid;
246	shmseg->shm_atime = time.tv_sec;
247	shmseg->shm_nattch++;
248	*retval = attach_va;
249	return 0;
250}
251
252struct shmctl_args {
253	int shmid;
254	int cmd;
255	struct shmat_ds *ubuf;
256};
257int
258shmctl(p, uap, retval)
259	struct proc *p;
260	struct shmctl_args *uap;
261	int *retval;
262{
263	int error, segnum;
264	struct ucred *cred = p->p_ucred;
265	struct shmid_ds inbuf;
266	struct shmid_ds *shmseg;
267
268	shmseg = shm_find_segment_by_shmid(uap->shmid);
269	if (shmseg == NULL)
270		return EINVAL;
271	switch (uap->cmd) {
272	case IPC_STAT:
273		if (error = ipcperm(cred, &shmseg->shm_perm, IPC_R))
274			return error;
275		if (error = copyout((caddr_t)shmseg, uap->ubuf, sizeof(inbuf)))
276			return error;
277		break;
278	case IPC_SET:
279		if (error = ipcperm(cred, &shmseg->shm_perm, IPC_M))
280			return error;
281		if (error = copyin(uap->ubuf, (caddr_t)&inbuf, sizeof(inbuf)))
282			return error;
283		shmseg->shm_perm.uid = inbuf.shm_perm.uid;
284		shmseg->shm_perm.gid = inbuf.shm_perm.gid;
285		shmseg->shm_perm.mode =
286		    (shmseg->shm_perm.mode & ~ACCESSPERMS) |
287		    (inbuf.shm_perm.mode & ACCESSPERMS);
288		shmseg->shm_ctime = time.tv_sec;
289		break;
290	case IPC_RMID:
291		if (error = ipcperm(cred, &shmseg->shm_perm, IPC_M))
292			return error;
293		shmseg->shm_perm.key = IPC_PRIVATE;
294		shmseg->shm_perm.mode |= SHMSEG_REMOVED;
295		if (shmseg->shm_nattch <= 0) {
296			shm_deallocate_segment(shmseg);
297			shm_last_free = IPCID_TO_IX(uap->shmid);
298		}
299		break;
300#if 0
301	case SHM_LOCK:
302	case SHM_UNLOCK:
303#endif
304	default:
305		return EINVAL;
306	}
307	return 0;
308}
309
310struct shmget_args {
311	key_t key;
312	size_t size;
313	int shmflg;
314};
315static int
316shmget_existing(p, uap, mode, segnum, retval)
317	struct proc *p;
318	struct shmget_args *uap;
319	int mode;
320	int segnum;
321	int *retval;
322{
323	struct shmid_ds *shmseg;
324	struct ucred *cred = p->p_ucred;
325	int error;
326
327	shmseg = &shmsegs[segnum];
328	if (shmseg->shm_perm.mode & SHMSEG_REMOVED) {
329		/*
330		 * This segment is in the process of being allocated.  Wait
331		 * until it's done, and look the key up again (in case the
332		 * allocation failed or it was freed).
333		 */
334		shmseg->shm_perm.mode |= SHMSEG_WANTED;
335		if (error =
336		    tsleep((caddr_t)shmseg, PLOCK | PCATCH, "shmget", 0))
337			return error;
338		return EAGAIN;
339	}
340	if (error = ipcperm(cred, &shmseg->shm_perm, mode))
341		return error;
342	if (uap->size && uap->size > shmseg->shm_segsz)
343		return EINVAL;
344	if (uap->shmflg & (IPC_CREAT | IPC_EXCL) == (IPC_CREAT | IPC_EXCL))
345		return EEXIST;
346	*retval = IXSEQ_TO_IPCID(segnum, shmseg->shm_perm);
347	return 0;
348}
349
350static int
351shmget_allocate_segment(p, uap, mode, retval)
352	struct proc *p;
353	struct shmget_args *uap;
354	int mode;
355	int *retval;
356{
357	int i, segnum, result, shmid, size;
358	struct ucred *cred = p->p_ucred;
359	struct shmid_ds *shmseg;
360	struct shm_handle *shm_handle;
361
362	if (uap->size < shminfo.shmmin || uap->size > shminfo.shmmax)
363		return EINVAL;
364	if (shm_nused >= shminfo.shmmni) /* any shmids left? */
365		return ENOSPC;
366	size = (uap->size + CLOFSET) & ~CLOFSET;
367	if (shm_committed + btoc(size) > shminfo.shmall)
368		return ENOMEM;
369	if (shm_last_free < 0) {
370		for (i = 0; i < shminfo.shmmni; i++)
371			if (shmsegs[i].shm_perm.mode & SHMSEG_FREE)
372				break;
373		if (i == shminfo.shmmni)
374			panic("shmseg free count inconsistent");
375		segnum = i;
376	} else  {
377		segnum = shm_last_free;
378		shm_last_free = -1;
379	}
380	shmseg = &shmsegs[segnum];
381	/*
382	 * In case we sleep in malloc(), mark the segment present but deleted
383	 * so that noone else tries to create the same key.
384	 */
385	shmseg->shm_perm.mode = SHMSEG_ALLOCATED | SHMSEG_REMOVED;
386	shmseg->shm_perm.key = uap->key;
387	shmseg->shm_perm.seq = (shmseg->shm_perm.seq + 1) & 0x7fff;
388	shm_handle = (struct shm_handle *)
389	    malloc(sizeof(struct shm_handle), M_SHM, M_WAITOK);
390	shmid = IXSEQ_TO_IPCID(segnum, shmseg->shm_perm);
391	result = vm_mmap(sysvshm_map, &shm_handle->kva, size, VM_PROT_ALL,
392	    VM_PROT_DEFAULT, MAP_ANON, (caddr_t) shmid, 0);
393	if (result != KERN_SUCCESS) {
394		shmseg->shm_perm.mode = SHMSEG_FREE;
395		shm_last_free = segnum;
396		free((caddr_t)shm_handle, M_SHM);
397		/* Just in case. */
398		wakeup((caddr_t)shmseg);
399		return ENOMEM;
400	}
401	shmseg->shm_internal = shm_handle;
402	shmseg->shm_perm.cuid = shmseg->shm_perm.uid = cred->cr_uid;
403	shmseg->shm_perm.cgid = shmseg->shm_perm.gid = cred->cr_gid;
404	shmseg->shm_perm.mode = (shmseg->shm_perm.mode & SHMSEG_WANTED) |
405	    (mode & ACCESSPERMS) | SHMSEG_ALLOCATED;
406	shmseg->shm_segsz = uap->size;
407	shmseg->shm_cpid = p->p_pid;
408	shmseg->shm_lpid = shmseg->shm_nattch = 0;
409	shmseg->shm_atime = shmseg->shm_dtime = 0;
410	shmseg->shm_ctime = time.tv_sec;
411	shm_committed += btoc(size);
412	shm_nused++;
413	if (shmseg->shm_perm.mode & SHMSEG_WANTED) {
414		/*
415		 * Somebody else wanted this key while we were asleep.  Wake
416		 * them up now.
417		 */
418		shmseg->shm_perm.mode &= ~SHMSEG_WANTED;
419		wakeup((caddr_t)shmseg);
420	}
421	*retval = shmid;
422	return 0;
423}
424
425int
426shmget(p, uap, retval)
427	struct proc *p;
428	struct shmget_args *uap;
429	int *retval;
430{
431	int segnum, mode, error;
432	struct shmid_ds *shmseg;
433
434	mode = uap->shmflg & ACCESSPERMS;
435	if (uap->key != IPC_PRIVATE) {
436	again:
437		segnum = shm_find_segment_by_key(uap->key);
438		if (segnum >= 0) {
439			error = shmget_existing(p, uap, mode, segnum, retval);
440			if (error == EAGAIN)
441				goto again;
442			return error;
443		}
444		if ((uap->shmflg & IPC_CREAT) == 0)
445			return ENOENT;
446	}
447	return shmget_allocate_segment(p, uap, mode, retval);
448}
449
450struct shmsys_args {
451	u_int	which;
452};
453int
454shmsys(p, uap, retval)
455	struct proc *p;
456	struct shmsys_args *uap;
457	int *retval;
458{
459
460	if (uap->which >= sizeof(shmcalls)/sizeof(shmcalls[0]))
461		return EINVAL;
462	return ((*shmcalls[uap->which])(p, &uap[1], retval));
463}
464
465void
466shmfork(p1, p2, isvfork)
467	struct proc *p1, *p2;
468	int isvfork;
469{
470	struct shmmap_state *shmmap_s;
471	size_t size;
472	int i;
473
474	size = shminfo.shmseg * sizeof(struct shmmap_state);
475	shmmap_s = malloc(size, M_SHM, M_WAITOK);
476	bcopy((caddr_t)p1->p_vmspace->vm_shm, (caddr_t)shmmap_s, size);
477	p2->p_vmspace->vm_shm = (caddr_t)shmmap_s;
478	for (i = 0; i < shminfo.shmseg; i++, shmmap_s++)
479		if (shmmap_s->shmid != -1)
480			shmsegs[IPCID_TO_IX(shmmap_s->shmid)].shm_nattch++;
481}
482
483void
484shmexit(p)
485	struct proc *p;
486{
487	struct shmmap_state *shmmap_s;
488	struct shmid_ds *shmseg;
489	int i;
490
491	shmmap_s = (struct shmmap_state *)p->p_vmspace->vm_shm;
492	for (i = 0; i < shminfo.shmseg; i++, shmmap_s++)
493		if (shmmap_s->shmid != -1)
494			shm_delete_mapping(p, shmmap_s);
495	free((caddr_t)p->p_vmspace->vm_shm, M_SHM);
496	p->p_vmspace->vm_shm = NULL;
497}
498
499void
500shminit()
501{
502	int i;
503	vm_offset_t garbage1, garbage2;
504
505	shminfo.shmmax *= NBPG;
506
507	/* actually this *should* be pageable.  SHM_{LOCK,UNLOCK} */
508	sysvshm_map = kmem_suballoc(kernel_map, &garbage1, &garbage2,
509				    shminfo.shmall * NBPG, TRUE);
510	for (i = 0; i < shminfo.shmmni; i++) {
511		shmsegs[i].shm_perm.mode = SHMSEG_FREE;
512		shmsegs[i].shm_perm.seq = 0;
513	}
514	shm_last_free = 0;
515	shm_nused = 0;
516	shm_committed = 0;
517}
518