[PATCH] use smp_mb/wmb/rmb where possible
[linux-3.10.git] / ipc / shm.c
1 /*
2  * linux/ipc/shm.c
3  * Copyright (C) 1992, 1993 Krishna Balasubramanian
4  *       Many improvements/fixes by Bruno Haible.
5  * Replaced `struct shm_desc' by `struct vm_area_struct', July 1994.
6  * Fixed the shm swap deallocation (shm_unuse()), August 1998 Andrea Arcangeli.
7  *
8  * /proc/sysvipc/shm support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
9  * BIGMEM support, Andrea Arcangeli <andrea@suse.de>
10  * SMP thread shm, Jean-Luc Boyard <jean-luc.boyard@siemens.fr>
11  * HIGHMEM support, Ingo Molnar <mingo@redhat.com>
12  * Make shmmax, shmall, shmmni sysctl'able, Christoph Rohland <cr@sap.com>
13  * Shared /dev/zero support, Kanoj Sarcar <kanoj@sgi.com>
14  * Move the mm functionality over to mm/shmem.c, Christoph Rohland <cr@sap.com>
15  *
16  */
17
18 #include <linux/config.h>
19 #include <linux/slab.h>
20 #include <linux/mm.h>
21 #include <linux/hugetlb.h>
22 #include <linux/shm.h>
23 #include <linux/init.h>
24 #include <linux/file.h>
25 #include <linux/mman.h>
26 #include <linux/proc_fs.h>
27 #include <linux/shmem_fs.h>
28 #include <linux/security.h>
29 #include <linux/syscalls.h>
30 #include <linux/audit.h>
31 #include <asm/uaccess.h>
32
33 #include "util.h"
34
35 #define shm_flags       shm_perm.mode
36
37 static struct file_operations shm_file_operations;
38 static struct vm_operations_struct shm_vm_ops;
39
40 static struct ipc_ids shm_ids;
41
42 #define shm_lock(id)    ((struct shmid_kernel*)ipc_lock(&shm_ids,id))
43 #define shm_unlock(shp) ipc_unlock(&(shp)->shm_perm)
44 #define shm_get(id)     ((struct shmid_kernel*)ipc_get(&shm_ids,id))
45 #define shm_buildid(id, seq) \
46         ipc_buildid(&shm_ids, id, seq)
47
48 static int newseg (key_t key, int shmflg, size_t size);
49 static void shm_open (struct vm_area_struct *shmd);
50 static void shm_close (struct vm_area_struct *shmd);
51 #ifdef CONFIG_PROC_FS
52 static int sysvipc_shm_read_proc(char *buffer, char **start, off_t offset, int length, int *eof, void *data);
53 #endif
54
55 size_t  shm_ctlmax = SHMMAX;
56 size_t  shm_ctlall = SHMALL;
57 int     shm_ctlmni = SHMMNI;
58
59 static int shm_tot; /* total number of shared memory pages */
60
61 void __init shm_init (void)
62 {
63         ipc_init_ids(&shm_ids, 1);
64 #ifdef CONFIG_PROC_FS
65         create_proc_read_entry("sysvipc/shm", 0, NULL, sysvipc_shm_read_proc, NULL);
66 #endif
67 }
68
69 static inline int shm_checkid(struct shmid_kernel *s, int id)
70 {
71         if (ipc_checkid(&shm_ids,&s->shm_perm,id))
72                 return -EIDRM;
73         return 0;
74 }
75
76 static inline struct shmid_kernel *shm_rmid(int id)
77 {
78         return (struct shmid_kernel *)ipc_rmid(&shm_ids,id);
79 }
80
81 static inline int shm_addid(struct shmid_kernel *shp)
82 {
83         return ipc_addid(&shm_ids, &shp->shm_perm, shm_ctlmni);
84 }
85
86
87
88 static inline void shm_inc (int id) {
89         struct shmid_kernel *shp;
90
91         if(!(shp = shm_lock(id)))
92                 BUG();
93         shp->shm_atim = get_seconds();
94         shp->shm_lprid = current->tgid;
95         shp->shm_nattch++;
96         shm_unlock(shp);
97 }
98
99 /* This is called by fork, once for every shm attach. */
100 static void shm_open (struct vm_area_struct *shmd)
101 {
102         shm_inc (shmd->vm_file->f_dentry->d_inode->i_ino);
103 }
104
105 /*
106  * shm_destroy - free the struct shmid_kernel
107  *
108  * @shp: struct to free
109  *
110  * It has to be called with shp and shm_ids.sem locked,
111  * but returns with shp unlocked and freed.
112  */
113 static void shm_destroy (struct shmid_kernel *shp)
114 {
115         shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT;
116         shm_rmid (shp->id);
117         shm_unlock(shp);
118         if (!is_file_hugepages(shp->shm_file))
119                 shmem_lock(shp->shm_file, 0, shp->mlock_user);
120         else
121                 user_shm_unlock(shp->shm_file->f_dentry->d_inode->i_size,
122                                                 shp->mlock_user);
123         fput (shp->shm_file);
124         security_shm_free(shp);
125         ipc_rcu_putref(shp);
126 }
127
128 /*
129  * remove the attach descriptor shmd.
130  * free memory for segment if it is marked destroyed.
131  * The descriptor has already been removed from the current->mm->mmap list
132  * and will later be kfree()d.
133  */
134 static void shm_close (struct vm_area_struct *shmd)
135 {
136         struct file * file = shmd->vm_file;
137         int id = file->f_dentry->d_inode->i_ino;
138         struct shmid_kernel *shp;
139
140         down (&shm_ids.sem);
141         /* remove from the list of attaches of the shm segment */
142         if(!(shp = shm_lock(id)))
143                 BUG();
144         shp->shm_lprid = current->tgid;
145         shp->shm_dtim = get_seconds();
146         shp->shm_nattch--;
147         if(shp->shm_nattch == 0 &&
148            shp->shm_flags & SHM_DEST)
149                 shm_destroy (shp);
150         else
151                 shm_unlock(shp);
152         up (&shm_ids.sem);
153 }
154
155 static int shm_mmap(struct file * file, struct vm_area_struct * vma)
156 {
157         file_accessed(file);
158         vma->vm_ops = &shm_vm_ops;
159         shm_inc(file->f_dentry->d_inode->i_ino);
160         return 0;
161 }
162
163 static struct file_operations shm_file_operations = {
164         .mmap   = shm_mmap
165 };
166
167 static struct vm_operations_struct shm_vm_ops = {
168         .open   = shm_open,     /* callback for a new vm-area open */
169         .close  = shm_close,    /* callback for when the vm-area is released */
170         .nopage = shmem_nopage,
171 #ifdef CONFIG_NUMA
172         .set_policy = shmem_set_policy,
173         .get_policy = shmem_get_policy,
174 #endif
175 };
176
177 static int newseg (key_t key, int shmflg, size_t size)
178 {
179         int error;
180         struct shmid_kernel *shp;
181         int numpages = (size + PAGE_SIZE -1) >> PAGE_SHIFT;
182         struct file * file;
183         char name[13];
184         int id;
185
186         if (size < SHMMIN || size > shm_ctlmax)
187                 return -EINVAL;
188
189         if (shm_tot + numpages >= shm_ctlall)
190                 return -ENOSPC;
191
192         shp = ipc_rcu_alloc(sizeof(*shp));
193         if (!shp)
194                 return -ENOMEM;
195
196         shp->shm_perm.key = key;
197         shp->shm_flags = (shmflg & S_IRWXUGO);
198         shp->mlock_user = NULL;
199
200         shp->shm_perm.security = NULL;
201         error = security_shm_alloc(shp);
202         if (error) {
203                 ipc_rcu_putref(shp);
204                 return error;
205         }
206
207         if (shmflg & SHM_HUGETLB) {
208                 /* hugetlb_zero_setup takes care of mlock user accounting */
209                 file = hugetlb_zero_setup(size);
210                 shp->mlock_user = current->user;
211         } else {
212                 sprintf (name, "SYSV%08x", key);
213                 file = shmem_file_setup(name, size, VM_ACCOUNT);
214         }
215         error = PTR_ERR(file);
216         if (IS_ERR(file))
217                 goto no_file;
218
219         error = -ENOSPC;
220         id = shm_addid(shp);
221         if(id == -1) 
222                 goto no_id;
223
224         shp->shm_cprid = current->tgid;
225         shp->shm_lprid = 0;
226         shp->shm_atim = shp->shm_dtim = 0;
227         shp->shm_ctim = get_seconds();
228         shp->shm_segsz = size;
229         shp->shm_nattch = 0;
230         shp->id = shm_buildid(id,shp->shm_perm.seq);
231         shp->shm_file = file;
232         file->f_dentry->d_inode->i_ino = shp->id;
233         if (shmflg & SHM_HUGETLB)
234                 set_file_hugepages(file);
235         else
236                 file->f_op = &shm_file_operations;
237         shm_tot += numpages;
238         shm_unlock(shp);
239         return shp->id;
240
241 no_id:
242         fput(file);
243 no_file:
244         security_shm_free(shp);
245         ipc_rcu_putref(shp);
246         return error;
247 }
248
249 asmlinkage long sys_shmget (key_t key, size_t size, int shmflg)
250 {
251         struct shmid_kernel *shp;
252         int err, id = 0;
253
254         down(&shm_ids.sem);
255         if (key == IPC_PRIVATE) {
256                 err = newseg(key, shmflg, size);
257         } else if ((id = ipc_findkey(&shm_ids, key)) == -1) {
258                 if (!(shmflg & IPC_CREAT))
259                         err = -ENOENT;
260                 else
261                         err = newseg(key, shmflg, size);
262         } else if ((shmflg & IPC_CREAT) && (shmflg & IPC_EXCL)) {
263                 err = -EEXIST;
264         } else {
265                 shp = shm_lock(id);
266                 if(shp==NULL)
267                         BUG();
268                 if (shp->shm_segsz < size)
269                         err = -EINVAL;
270                 else if (ipcperms(&shp->shm_perm, shmflg))
271                         err = -EACCES;
272                 else {
273                         int shmid = shm_buildid(id, shp->shm_perm.seq);
274                         err = security_shm_associate(shp, shmflg);
275                         if (!err)
276                                 err = shmid;
277                 }
278                 shm_unlock(shp);
279         }
280         up(&shm_ids.sem);
281
282         return err;
283 }
284
285 static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version)
286 {
287         switch(version) {
288         case IPC_64:
289                 return copy_to_user(buf, in, sizeof(*in));
290         case IPC_OLD:
291             {
292                 struct shmid_ds out;
293
294                 ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
295                 out.shm_segsz   = in->shm_segsz;
296                 out.shm_atime   = in->shm_atime;
297                 out.shm_dtime   = in->shm_dtime;
298                 out.shm_ctime   = in->shm_ctime;
299                 out.shm_cpid    = in->shm_cpid;
300                 out.shm_lpid    = in->shm_lpid;
301                 out.shm_nattch  = in->shm_nattch;
302
303                 return copy_to_user(buf, &out, sizeof(out));
304             }
305         default:
306                 return -EINVAL;
307         }
308 }
309
310 struct shm_setbuf {
311         uid_t   uid;
312         gid_t   gid;
313         mode_t  mode;
314 };      
315
316 static inline unsigned long copy_shmid_from_user(struct shm_setbuf *out, void __user *buf, int version)
317 {
318         switch(version) {
319         case IPC_64:
320             {
321                 struct shmid64_ds tbuf;
322
323                 if (copy_from_user(&tbuf, buf, sizeof(tbuf)))
324                         return -EFAULT;
325
326                 out->uid        = tbuf.shm_perm.uid;
327                 out->gid        = tbuf.shm_perm.gid;
328                 out->mode       = tbuf.shm_flags;
329
330                 return 0;
331             }
332         case IPC_OLD:
333             {
334                 struct shmid_ds tbuf_old;
335
336                 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
337                         return -EFAULT;
338
339                 out->uid        = tbuf_old.shm_perm.uid;
340                 out->gid        = tbuf_old.shm_perm.gid;
341                 out->mode       = tbuf_old.shm_flags;
342
343                 return 0;
344             }
345         default:
346                 return -EINVAL;
347         }
348 }
349
350 static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminfo64 *in, int version)
351 {
352         switch(version) {
353         case IPC_64:
354                 return copy_to_user(buf, in, sizeof(*in));
355         case IPC_OLD:
356             {
357                 struct shminfo out;
358
359                 if(in->shmmax > INT_MAX)
360                         out.shmmax = INT_MAX;
361                 else
362                         out.shmmax = (int)in->shmmax;
363
364                 out.shmmin      = in->shmmin;
365                 out.shmmni      = in->shmmni;
366                 out.shmseg      = in->shmseg;
367                 out.shmall      = in->shmall; 
368
369                 return copy_to_user(buf, &out, sizeof(out));
370             }
371         default:
372                 return -EINVAL;
373         }
374 }
375
376 static void shm_get_stat(unsigned long *rss, unsigned long *swp) 
377 {
378         int i;
379
380         *rss = 0;
381         *swp = 0;
382
383         for (i = 0; i <= shm_ids.max_id; i++) {
384                 struct shmid_kernel *shp;
385                 struct inode *inode;
386
387                 shp = shm_get(i);
388                 if(!shp)
389                         continue;
390
391                 inode = shp->shm_file->f_dentry->d_inode;
392
393                 if (is_file_hugepages(shp->shm_file)) {
394                         struct address_space *mapping = inode->i_mapping;
395                         *rss += (HPAGE_SIZE/PAGE_SIZE)*mapping->nrpages;
396                 } else {
397                         struct shmem_inode_info *info = SHMEM_I(inode);
398                         spin_lock(&info->lock);
399                         *rss += inode->i_mapping->nrpages;
400                         *swp += info->swapped;
401                         spin_unlock(&info->lock);
402                 }
403         }
404 }
405
406 asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds __user *buf)
407 {
408         struct shm_setbuf setbuf;
409         struct shmid_kernel *shp;
410         int err, version;
411
412         if (cmd < 0 || shmid < 0) {
413                 err = -EINVAL;
414                 goto out;
415         }
416
417         version = ipc_parse_version(&cmd);
418
419         switch (cmd) { /* replace with proc interface ? */
420         case IPC_INFO:
421         {
422                 struct shminfo64 shminfo;
423
424                 err = security_shm_shmctl(NULL, cmd);
425                 if (err)
426                         return err;
427
428                 memset(&shminfo,0,sizeof(shminfo));
429                 shminfo.shmmni = shminfo.shmseg = shm_ctlmni;
430                 shminfo.shmmax = shm_ctlmax;
431                 shminfo.shmall = shm_ctlall;
432
433                 shminfo.shmmin = SHMMIN;
434                 if(copy_shminfo_to_user (buf, &shminfo, version))
435                         return -EFAULT;
436                 /* reading a integer is always atomic */
437                 err= shm_ids.max_id;
438                 if(err<0)
439                         err = 0;
440                 goto out;
441         }
442         case SHM_INFO:
443         {
444                 struct shm_info shm_info;
445
446                 err = security_shm_shmctl(NULL, cmd);
447                 if (err)
448                         return err;
449
450                 memset(&shm_info,0,sizeof(shm_info));
451                 down(&shm_ids.sem);
452                 shm_info.used_ids = shm_ids.in_use;
453                 shm_get_stat (&shm_info.shm_rss, &shm_info.shm_swp);
454                 shm_info.shm_tot = shm_tot;
455                 shm_info.swap_attempts = 0;
456                 shm_info.swap_successes = 0;
457                 err = shm_ids.max_id;
458                 up(&shm_ids.sem);
459                 if(copy_to_user (buf, &shm_info, sizeof(shm_info))) {
460                         err = -EFAULT;
461                         goto out;
462                 }
463
464                 err = err < 0 ? 0 : err;
465                 goto out;
466         }
467         case SHM_STAT:
468         case IPC_STAT:
469         {
470                 struct shmid64_ds tbuf;
471                 int result;
472                 memset(&tbuf, 0, sizeof(tbuf));
473                 shp = shm_lock(shmid);
474                 if(shp==NULL) {
475                         err = -EINVAL;
476                         goto out;
477                 } else if(cmd==SHM_STAT) {
478                         err = -EINVAL;
479                         if (shmid > shm_ids.max_id)
480                                 goto out_unlock;
481                         result = shm_buildid(shmid, shp->shm_perm.seq);
482                 } else {
483                         err = shm_checkid(shp,shmid);
484                         if(err)
485                                 goto out_unlock;
486                         result = 0;
487                 }
488                 err=-EACCES;
489                 if (ipcperms (&shp->shm_perm, S_IRUGO))
490                         goto out_unlock;
491                 err = security_shm_shmctl(shp, cmd);
492                 if (err)
493                         goto out_unlock;
494                 kernel_to_ipc64_perm(&shp->shm_perm, &tbuf.shm_perm);
495                 tbuf.shm_segsz  = shp->shm_segsz;
496                 tbuf.shm_atime  = shp->shm_atim;
497                 tbuf.shm_dtime  = shp->shm_dtim;
498                 tbuf.shm_ctime  = shp->shm_ctim;
499                 tbuf.shm_cpid   = shp->shm_cprid;
500                 tbuf.shm_lpid   = shp->shm_lprid;
501                 if (!is_file_hugepages(shp->shm_file))
502                         tbuf.shm_nattch = shp->shm_nattch;
503                 else
504                         tbuf.shm_nattch = file_count(shp->shm_file) - 1;
505                 shm_unlock(shp);
506                 if(copy_shmid_to_user (buf, &tbuf, version))
507                         err = -EFAULT;
508                 else
509                         err = result;
510                 goto out;
511         }
512         case SHM_LOCK:
513         case SHM_UNLOCK:
514         {
515                 shp = shm_lock(shmid);
516                 if(shp==NULL) {
517                         err = -EINVAL;
518                         goto out;
519                 }
520                 err = shm_checkid(shp,shmid);
521                 if(err)
522                         goto out_unlock;
523
524                 if (!capable(CAP_IPC_LOCK)) {
525                         err = -EPERM;
526                         if (current->euid != shp->shm_perm.uid &&
527                             current->euid != shp->shm_perm.cuid)
528                                 goto out_unlock;
529                         if (cmd == SHM_LOCK &&
530                             !current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur)
531                                 goto out_unlock;
532                 }
533
534                 err = security_shm_shmctl(shp, cmd);
535                 if (err)
536                         goto out_unlock;
537                 
538                 if(cmd==SHM_LOCK) {
539                         struct user_struct * user = current->user;
540                         if (!is_file_hugepages(shp->shm_file)) {
541                                 err = shmem_lock(shp->shm_file, 1, user);
542                                 if (!err) {
543                                         shp->shm_flags |= SHM_LOCKED;
544                                         shp->mlock_user = user;
545                                 }
546                         }
547                 } else if (!is_file_hugepages(shp->shm_file)) {
548                         shmem_lock(shp->shm_file, 0, shp->mlock_user);
549                         shp->shm_flags &= ~SHM_LOCKED;
550                         shp->mlock_user = NULL;
551                 }
552                 shm_unlock(shp);
553                 goto out;
554         }
555         case IPC_RMID:
556         {
557                 /*
558                  *      We cannot simply remove the file. The SVID states
559                  *      that the block remains until the last person
560                  *      detaches from it, then is deleted. A shmat() on
561                  *      an RMID segment is legal in older Linux and if 
562                  *      we change it apps break...
563                  *
564                  *      Instead we set a destroyed flag, and then blow
565                  *      the name away when the usage hits zero.
566                  */
567                 down(&shm_ids.sem);
568                 shp = shm_lock(shmid);
569                 err = -EINVAL;
570                 if (shp == NULL) 
571                         goto out_up;
572                 err = shm_checkid(shp, shmid);
573                 if(err)
574                         goto out_unlock_up;
575
576                 if (current->euid != shp->shm_perm.uid &&
577                     current->euid != shp->shm_perm.cuid && 
578                     !capable(CAP_SYS_ADMIN)) {
579                         err=-EPERM;
580                         goto out_unlock_up;
581                 }
582
583                 err = security_shm_shmctl(shp, cmd);
584                 if (err)
585                         goto out_unlock_up;
586
587                 if (shp->shm_nattch){
588                         shp->shm_flags |= SHM_DEST;
589                         /* Do not find it any more */
590                         shp->shm_perm.key = IPC_PRIVATE;
591                         shm_unlock(shp);
592                 } else
593                         shm_destroy (shp);
594                 up(&shm_ids.sem);
595                 goto out;
596         }
597
598         case IPC_SET:
599         {
600                 if (copy_shmid_from_user (&setbuf, buf, version)) {
601                         err = -EFAULT;
602                         goto out;
603                 }
604                 if ((err = audit_ipc_perms(0, setbuf.uid, setbuf.gid, setbuf.mode)))
605                         return err;
606                 down(&shm_ids.sem);
607                 shp = shm_lock(shmid);
608                 err=-EINVAL;
609                 if(shp==NULL)
610                         goto out_up;
611                 err = shm_checkid(shp,shmid);
612                 if(err)
613                         goto out_unlock_up;
614                 err=-EPERM;
615                 if (current->euid != shp->shm_perm.uid &&
616                     current->euid != shp->shm_perm.cuid && 
617                     !capable(CAP_SYS_ADMIN)) {
618                         goto out_unlock_up;
619                 }
620
621                 err = security_shm_shmctl(shp, cmd);
622                 if (err)
623                         goto out_unlock_up;
624                 
625                 shp->shm_perm.uid = setbuf.uid;
626                 shp->shm_perm.gid = setbuf.gid;
627                 shp->shm_flags = (shp->shm_flags & ~S_IRWXUGO)
628                         | (setbuf.mode & S_IRWXUGO);
629                 shp->shm_ctim = get_seconds();
630                 break;
631         }
632
633         default:
634                 err = -EINVAL;
635                 goto out;
636         }
637
638         err = 0;
639 out_unlock_up:
640         shm_unlock(shp);
641 out_up:
642         up(&shm_ids.sem);
643         goto out;
644 out_unlock:
645         shm_unlock(shp);
646 out:
647         return err;
648 }
649
650 /*
651  * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
652  *
653  * NOTE! Despite the name, this is NOT a direct system call entrypoint. The
654  * "raddr" thing points to kernel space, and there has to be a wrapper around
655  * this.
656  */
657 long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr)
658 {
659         struct shmid_kernel *shp;
660         unsigned long addr;
661         unsigned long size;
662         struct file * file;
663         int    err;
664         unsigned long flags;
665         unsigned long prot;
666         unsigned long o_flags;
667         int acc_mode;
668         void *user_addr;
669
670         if (shmid < 0) {
671                 err = -EINVAL;
672                 goto out;
673         } else if ((addr = (ulong)shmaddr)) {
674                 if (addr & (SHMLBA-1)) {
675                         if (shmflg & SHM_RND)
676                                 addr &= ~(SHMLBA-1);       /* round down */
677                         else
678 #ifndef __ARCH_FORCE_SHMLBA
679                                 if (addr & ~PAGE_MASK)
680 #endif
681                                         return -EINVAL;
682                 }
683                 flags = MAP_SHARED | MAP_FIXED;
684         } else {
685                 if ((shmflg & SHM_REMAP))
686                         return -EINVAL;
687
688                 flags = MAP_SHARED;
689         }
690
691         if (shmflg & SHM_RDONLY) {
692                 prot = PROT_READ;
693                 o_flags = O_RDONLY;
694                 acc_mode = S_IRUGO;
695         } else {
696                 prot = PROT_READ | PROT_WRITE;
697                 o_flags = O_RDWR;
698                 acc_mode = S_IRUGO | S_IWUGO;
699         }
700         if (shmflg & SHM_EXEC) {
701                 prot |= PROT_EXEC;
702                 acc_mode |= S_IXUGO;
703         }
704
705         /*
706          * We cannot rely on the fs check since SYSV IPC does have an
707          * additional creator id...
708          */
709         shp = shm_lock(shmid);
710         if(shp == NULL) {
711                 err = -EINVAL;
712                 goto out;
713         }
714         err = shm_checkid(shp,shmid);
715         if (err) {
716                 shm_unlock(shp);
717                 goto out;
718         }
719         if (ipcperms(&shp->shm_perm, acc_mode)) {
720                 shm_unlock(shp);
721                 err = -EACCES;
722                 goto out;
723         }
724
725         err = security_shm_shmat(shp, shmaddr, shmflg);
726         if (err) {
727                 shm_unlock(shp);
728                 return err;
729         }
730                 
731         file = shp->shm_file;
732         size = i_size_read(file->f_dentry->d_inode);
733         shp->shm_nattch++;
734         shm_unlock(shp);
735
736         down_write(&current->mm->mmap_sem);
737         if (addr && !(shmflg & SHM_REMAP)) {
738                 user_addr = ERR_PTR(-EINVAL);
739                 if (find_vma_intersection(current->mm, addr, addr + size))
740                         goto invalid;
741                 /*
742                  * If shm segment goes below stack, make sure there is some
743                  * space left for the stack to grow (at least 4 pages).
744                  */
745                 if (addr < current->mm->start_stack &&
746                     addr > current->mm->start_stack - size - PAGE_SIZE * 5)
747                         goto invalid;
748         }
749                 
750         user_addr = (void*) do_mmap (file, addr, size, prot, flags, 0);
751
752 invalid:
753         up_write(&current->mm->mmap_sem);
754
755         down (&shm_ids.sem);
756         if(!(shp = shm_lock(shmid)))
757                 BUG();
758         shp->shm_nattch--;
759         if(shp->shm_nattch == 0 &&
760            shp->shm_flags & SHM_DEST)
761                 shm_destroy (shp);
762         else
763                 shm_unlock(shp);
764         up (&shm_ids.sem);
765
766         *raddr = (unsigned long) user_addr;
767         err = 0;
768         if (IS_ERR(user_addr))
769                 err = PTR_ERR(user_addr);
770 out:
771         return err;
772 }
773
774 /*
775  * detach and kill segment if marked destroyed.
776  * The work is done in shm_close.
777  */
778 asmlinkage long sys_shmdt(char __user *shmaddr)
779 {
780         struct mm_struct *mm = current->mm;
781         struct vm_area_struct *vma, *next;
782         unsigned long addr = (unsigned long)shmaddr;
783         loff_t size = 0;
784         int retval = -EINVAL;
785
786         down_write(&mm->mmap_sem);
787
788         /*
789          * This function tries to be smart and unmap shm segments that
790          * were modified by partial mlock or munmap calls:
791          * - It first determines the size of the shm segment that should be
792          *   unmapped: It searches for a vma that is backed by shm and that
793          *   started at address shmaddr. It records it's size and then unmaps
794          *   it.
795          * - Then it unmaps all shm vmas that started at shmaddr and that
796          *   are within the initially determined size.
797          * Errors from do_munmap are ignored: the function only fails if
798          * it's called with invalid parameters or if it's called to unmap
799          * a part of a vma. Both calls in this function are for full vmas,
800          * the parameters are directly copied from the vma itself and always
801          * valid - therefore do_munmap cannot fail. (famous last words?)
802          */
803         /*
804          * If it had been mremap()'d, the starting address would not
805          * match the usual checks anyway. So assume all vma's are
806          * above the starting address given.
807          */
808         vma = find_vma(mm, addr);
809
810         while (vma) {
811                 next = vma->vm_next;
812
813                 /*
814                  * Check if the starting address would match, i.e. it's
815                  * a fragment created by mprotect() and/or munmap(), or it
816                  * otherwise it starts at this address with no hassles.
817                  */
818                 if ((vma->vm_ops == &shm_vm_ops || is_vm_hugetlb_page(vma)) &&
819                         (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) {
820
821
822                         size = vma->vm_file->f_dentry->d_inode->i_size;
823                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
824                         /*
825                          * We discovered the size of the shm segment, so
826                          * break out of here and fall through to the next
827                          * loop that uses the size information to stop
828                          * searching for matching vma's.
829                          */
830                         retval = 0;
831                         vma = next;
832                         break;
833                 }
834                 vma = next;
835         }
836
837         /*
838          * We need look no further than the maximum address a fragment
839          * could possibly have landed at. Also cast things to loff_t to
840          * prevent overflows and make comparisions vs. equal-width types.
841          */
842         while (vma && (loff_t)(vma->vm_end - addr) <= size) {
843                 next = vma->vm_next;
844
845                 /* finding a matching vma now does not alter retval */
846                 if ((vma->vm_ops == &shm_vm_ops || is_vm_hugetlb_page(vma)) &&
847                         (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff)
848
849                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
850                 vma = next;
851         }
852
853         up_write(&mm->mmap_sem);
854         return retval;
855 }
856
857 #ifdef CONFIG_PROC_FS
858 static int sysvipc_shm_read_proc(char *buffer, char **start, off_t offset, int length, int *eof, void *data)
859 {
860         off_t pos = 0;
861         off_t begin = 0;
862         int i, len = 0;
863
864         down(&shm_ids.sem);
865         len += sprintf(buffer, "       key      shmid perms       size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime\n");
866
867         for(i = 0; i <= shm_ids.max_id; i++) {
868                 struct shmid_kernel* shp;
869
870                 shp = shm_lock(i);
871                 if(shp!=NULL) {
872 #define SMALL_STRING "%10d %10d  %4o %10u %5u %5u  %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
873 #define BIG_STRING   "%10d %10d  %4o %21u %5u %5u  %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
874                         char *format;
875
876                         if (sizeof(size_t) <= sizeof(int))
877                                 format = SMALL_STRING;
878                         else
879                                 format = BIG_STRING;
880                         len += sprintf(buffer + len, format,
881                                 shp->shm_perm.key,
882                                 shm_buildid(i, shp->shm_perm.seq),
883                                 shp->shm_flags,
884                                 shp->shm_segsz,
885                                 shp->shm_cprid,
886                                 shp->shm_lprid,
887                                 is_file_hugepages(shp->shm_file) ? (file_count(shp->shm_file) - 1) : shp->shm_nattch,
888                                 shp->shm_perm.uid,
889                                 shp->shm_perm.gid,
890                                 shp->shm_perm.cuid,
891                                 shp->shm_perm.cgid,
892                                 shp->shm_atim,
893                                 shp->shm_dtim,
894                                 shp->shm_ctim);
895                         shm_unlock(shp);
896
897                         pos += len;
898                         if(pos < offset) {
899                                 len = 0;
900                                 begin = pos;
901                         }
902                         if(pos > offset + length)
903                                 goto done;
904                 }
905         }
906         *eof = 1;
907 done:
908         up(&shm_ids.sem);
909         *start = buffer + (offset - begin);
910         len -= (offset - begin);
911         if(len > length)
912                 len = length;
913         if(len < 0)
914                 len = 0;
915         return len;
916 }
917 #endif