[PATCH] hugetlb: remove repeated code
[linux-2.6.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/shmem_fs.h>
27 #include <linux/security.h>
28 #include <linux/syscalls.h>
29 #include <linux/audit.h>
30 #include <linux/ptrace.h>
31 #include <linux/seq_file.h>
32
33 #include <asm/uaccess.h>
34
35 #include "util.h"
36
37 #define shm_flags       shm_perm.mode
38
39 static struct file_operations shm_file_operations;
40 static struct vm_operations_struct shm_vm_ops;
41
42 static struct ipc_ids shm_ids;
43
44 #define shm_lock(id)    ((struct shmid_kernel*)ipc_lock(&shm_ids,id))
45 #define shm_unlock(shp) ipc_unlock(&(shp)->shm_perm)
46 #define shm_get(id)     ((struct shmid_kernel*)ipc_get(&shm_ids,id))
47 #define shm_buildid(id, seq) \
48         ipc_buildid(&shm_ids, id, seq)
49
50 static int newseg (key_t key, int shmflg, size_t size);
51 static void shm_open (struct vm_area_struct *shmd);
52 static void shm_close (struct vm_area_struct *shmd);
53 #ifdef CONFIG_PROC_FS
54 static int sysvipc_shm_proc_show(struct seq_file *s, void *it);
55 #endif
56
57 size_t  shm_ctlmax = SHMMAX;
58 size_t  shm_ctlall = SHMALL;
59 int     shm_ctlmni = SHMMNI;
60
61 static int shm_tot; /* total number of shared memory pages */
62
63 void __init shm_init (void)
64 {
65         ipc_init_ids(&shm_ids, 1);
66         ipc_init_proc_interface("sysvipc/shm",
67                                 "       key      shmid perms       size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime\n",
68                                 &shm_ids,
69                                 sysvipc_shm_proc_show);
70 }
71
72 static inline int shm_checkid(struct shmid_kernel *s, int id)
73 {
74         if (ipc_checkid(&shm_ids,&s->shm_perm,id))
75                 return -EIDRM;
76         return 0;
77 }
78
79 static inline struct shmid_kernel *shm_rmid(int id)
80 {
81         return (struct shmid_kernel *)ipc_rmid(&shm_ids,id);
82 }
83
84 static inline int shm_addid(struct shmid_kernel *shp)
85 {
86         return ipc_addid(&shm_ids, &shp->shm_perm, shm_ctlmni);
87 }
88
89
90
91 static inline void shm_inc (int id) {
92         struct shmid_kernel *shp;
93
94         if(!(shp = shm_lock(id)))
95                 BUG();
96         shp->shm_atim = get_seconds();
97         shp->shm_lprid = current->tgid;
98         shp->shm_nattch++;
99         shm_unlock(shp);
100 }
101
102 /* This is called by fork, once for every shm attach. */
103 static void shm_open (struct vm_area_struct *shmd)
104 {
105         shm_inc (shmd->vm_file->f_dentry->d_inode->i_ino);
106 }
107
108 /*
109  * shm_destroy - free the struct shmid_kernel
110  *
111  * @shp: struct to free
112  *
113  * It has to be called with shp and shm_ids.sem locked,
114  * but returns with shp unlocked and freed.
115  */
116 static void shm_destroy (struct shmid_kernel *shp)
117 {
118         shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT;
119         shm_rmid (shp->id);
120         shm_unlock(shp);
121         if (!is_file_hugepages(shp->shm_file))
122                 shmem_lock(shp->shm_file, 0, shp->mlock_user);
123         else
124                 user_shm_unlock(shp->shm_file->f_dentry->d_inode->i_size,
125                                                 shp->mlock_user);
126         fput (shp->shm_file);
127         security_shm_free(shp);
128         ipc_rcu_putref(shp);
129 }
130
131 /*
132  * remove the attach descriptor shmd.
133  * free memory for segment if it is marked destroyed.
134  * The descriptor has already been removed from the current->mm->mmap list
135  * and will later be kfree()d.
136  */
137 static void shm_close (struct vm_area_struct *shmd)
138 {
139         struct file * file = shmd->vm_file;
140         int id = file->f_dentry->d_inode->i_ino;
141         struct shmid_kernel *shp;
142
143         down (&shm_ids.sem);
144         /* remove from the list of attaches of the shm segment */
145         if(!(shp = shm_lock(id)))
146                 BUG();
147         shp->shm_lprid = current->tgid;
148         shp->shm_dtim = get_seconds();
149         shp->shm_nattch--;
150         if(shp->shm_nattch == 0 &&
151            shp->shm_flags & SHM_DEST)
152                 shm_destroy (shp);
153         else
154                 shm_unlock(shp);
155         up (&shm_ids.sem);
156 }
157
158 static int shm_mmap(struct file * file, struct vm_area_struct * vma)
159 {
160         file_accessed(file);
161         vma->vm_ops = &shm_vm_ops;
162         shm_inc(file->f_dentry->d_inode->i_ino);
163         return 0;
164 }
165
166 static struct file_operations shm_file_operations = {
167         .mmap   = shm_mmap
168 };
169
170 static struct vm_operations_struct shm_vm_ops = {
171         .open   = shm_open,     /* callback for a new vm-area open */
172         .close  = shm_close,    /* callback for when the vm-area is released */
173         .nopage = shmem_nopage,
174 #if defined(CONFIG_NUMA) && defined(CONFIG_SHMEM)
175         .set_policy = shmem_set_policy,
176         .get_policy = shmem_get_policy,
177 #endif
178 };
179
180 static int newseg (key_t key, int shmflg, size_t size)
181 {
182         int error;
183         struct shmid_kernel *shp;
184         int numpages = (size + PAGE_SIZE -1) >> PAGE_SHIFT;
185         struct file * file;
186         char name[13];
187         int id;
188
189         if (size < SHMMIN || size > shm_ctlmax)
190                 return -EINVAL;
191
192         if (shm_tot + numpages >= shm_ctlall)
193                 return -ENOSPC;
194
195         shp = ipc_rcu_alloc(sizeof(*shp));
196         if (!shp)
197                 return -ENOMEM;
198
199         shp->shm_perm.key = key;
200         shp->shm_flags = (shmflg & S_IRWXUGO);
201         shp->mlock_user = NULL;
202
203         shp->shm_perm.security = NULL;
204         error = security_shm_alloc(shp);
205         if (error) {
206                 ipc_rcu_putref(shp);
207                 return error;
208         }
209
210         if (shmflg & SHM_HUGETLB) {
211                 /* hugetlb_zero_setup takes care of mlock user accounting */
212                 file = hugetlb_zero_setup(size);
213                 shp->mlock_user = current->user;
214         } else {
215                 sprintf (name, "SYSV%08x", key);
216                 file = shmem_file_setup(name, size, VM_ACCOUNT);
217         }
218         error = PTR_ERR(file);
219         if (IS_ERR(file))
220                 goto no_file;
221
222         error = -ENOSPC;
223         id = shm_addid(shp);
224         if(id == -1) 
225                 goto no_id;
226
227         shp->shm_cprid = current->tgid;
228         shp->shm_lprid = 0;
229         shp->shm_atim = shp->shm_dtim = 0;
230         shp->shm_ctim = get_seconds();
231         shp->shm_segsz = size;
232         shp->shm_nattch = 0;
233         shp->id = shm_buildid(id,shp->shm_perm.seq);
234         shp->shm_file = file;
235         file->f_dentry->d_inode->i_ino = shp->id;
236
237         /* Hugetlb ops would have already been assigned. */
238         if (!(shmflg & SHM_HUGETLB))
239                 file->f_op = &shm_file_operations;
240
241         shm_tot += numpages;
242         shm_unlock(shp);
243         return shp->id;
244
245 no_id:
246         fput(file);
247 no_file:
248         security_shm_free(shp);
249         ipc_rcu_putref(shp);
250         return error;
251 }
252
253 asmlinkage long sys_shmget (key_t key, size_t size, int shmflg)
254 {
255         struct shmid_kernel *shp;
256         int err, id = 0;
257
258         down(&shm_ids.sem);
259         if (key == IPC_PRIVATE) {
260                 err = newseg(key, shmflg, size);
261         } else if ((id = ipc_findkey(&shm_ids, key)) == -1) {
262                 if (!(shmflg & IPC_CREAT))
263                         err = -ENOENT;
264                 else
265                         err = newseg(key, shmflg, size);
266         } else if ((shmflg & IPC_CREAT) && (shmflg & IPC_EXCL)) {
267                 err = -EEXIST;
268         } else {
269                 shp = shm_lock(id);
270                 if(shp==NULL)
271                         BUG();
272                 if (shp->shm_segsz < size)
273                         err = -EINVAL;
274                 else if (ipcperms(&shp->shm_perm, shmflg))
275                         err = -EACCES;
276                 else {
277                         int shmid = shm_buildid(id, shp->shm_perm.seq);
278                         err = security_shm_associate(shp, shmflg);
279                         if (!err)
280                                 err = shmid;
281                 }
282                 shm_unlock(shp);
283         }
284         up(&shm_ids.sem);
285
286         return err;
287 }
288
289 static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version)
290 {
291         switch(version) {
292         case IPC_64:
293                 return copy_to_user(buf, in, sizeof(*in));
294         case IPC_OLD:
295             {
296                 struct shmid_ds out;
297
298                 ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
299                 out.shm_segsz   = in->shm_segsz;
300                 out.shm_atime   = in->shm_atime;
301                 out.shm_dtime   = in->shm_dtime;
302                 out.shm_ctime   = in->shm_ctime;
303                 out.shm_cpid    = in->shm_cpid;
304                 out.shm_lpid    = in->shm_lpid;
305                 out.shm_nattch  = in->shm_nattch;
306
307                 return copy_to_user(buf, &out, sizeof(out));
308             }
309         default:
310                 return -EINVAL;
311         }
312 }
313
314 struct shm_setbuf {
315         uid_t   uid;
316         gid_t   gid;
317         mode_t  mode;
318 };      
319
320 static inline unsigned long copy_shmid_from_user(struct shm_setbuf *out, void __user *buf, int version)
321 {
322         switch(version) {
323         case IPC_64:
324             {
325                 struct shmid64_ds tbuf;
326
327                 if (copy_from_user(&tbuf, buf, sizeof(tbuf)))
328                         return -EFAULT;
329
330                 out->uid        = tbuf.shm_perm.uid;
331                 out->gid        = tbuf.shm_perm.gid;
332                 out->mode       = tbuf.shm_flags;
333
334                 return 0;
335             }
336         case IPC_OLD:
337             {
338                 struct shmid_ds tbuf_old;
339
340                 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
341                         return -EFAULT;
342
343                 out->uid        = tbuf_old.shm_perm.uid;
344                 out->gid        = tbuf_old.shm_perm.gid;
345                 out->mode       = tbuf_old.shm_flags;
346
347                 return 0;
348             }
349         default:
350                 return -EINVAL;
351         }
352 }
353
354 static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminfo64 *in, int version)
355 {
356         switch(version) {
357         case IPC_64:
358                 return copy_to_user(buf, in, sizeof(*in));
359         case IPC_OLD:
360             {
361                 struct shminfo out;
362
363                 if(in->shmmax > INT_MAX)
364                         out.shmmax = INT_MAX;
365                 else
366                         out.shmmax = (int)in->shmmax;
367
368                 out.shmmin      = in->shmmin;
369                 out.shmmni      = in->shmmni;
370                 out.shmseg      = in->shmseg;
371                 out.shmall      = in->shmall; 
372
373                 return copy_to_user(buf, &out, sizeof(out));
374             }
375         default:
376                 return -EINVAL;
377         }
378 }
379
380 static void shm_get_stat(unsigned long *rss, unsigned long *swp) 
381 {
382         int i;
383
384         *rss = 0;
385         *swp = 0;
386
387         for (i = 0; i <= shm_ids.max_id; i++) {
388                 struct shmid_kernel *shp;
389                 struct inode *inode;
390
391                 shp = shm_get(i);
392                 if(!shp)
393                         continue;
394
395                 inode = shp->shm_file->f_dentry->d_inode;
396
397                 if (is_file_hugepages(shp->shm_file)) {
398                         struct address_space *mapping = inode->i_mapping;
399                         *rss += (HPAGE_SIZE/PAGE_SIZE)*mapping->nrpages;
400                 } else {
401                         struct shmem_inode_info *info = SHMEM_I(inode);
402                         spin_lock(&info->lock);
403                         *rss += inode->i_mapping->nrpages;
404                         *swp += info->swapped;
405                         spin_unlock(&info->lock);
406                 }
407         }
408 }
409
410 asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds __user *buf)
411 {
412         struct shm_setbuf setbuf;
413         struct shmid_kernel *shp;
414         int err, version;
415
416         if (cmd < 0 || shmid < 0) {
417                 err = -EINVAL;
418                 goto out;
419         }
420
421         version = ipc_parse_version(&cmd);
422
423         switch (cmd) { /* replace with proc interface ? */
424         case IPC_INFO:
425         {
426                 struct shminfo64 shminfo;
427
428                 err = security_shm_shmctl(NULL, cmd);
429                 if (err)
430                         return err;
431
432                 memset(&shminfo,0,sizeof(shminfo));
433                 shminfo.shmmni = shminfo.shmseg = shm_ctlmni;
434                 shminfo.shmmax = shm_ctlmax;
435                 shminfo.shmall = shm_ctlall;
436
437                 shminfo.shmmin = SHMMIN;
438                 if(copy_shminfo_to_user (buf, &shminfo, version))
439                         return -EFAULT;
440                 /* reading a integer is always atomic */
441                 err= shm_ids.max_id;
442                 if(err<0)
443                         err = 0;
444                 goto out;
445         }
446         case SHM_INFO:
447         {
448                 struct shm_info shm_info;
449
450                 err = security_shm_shmctl(NULL, cmd);
451                 if (err)
452                         return err;
453
454                 memset(&shm_info,0,sizeof(shm_info));
455                 down(&shm_ids.sem);
456                 shm_info.used_ids = shm_ids.in_use;
457                 shm_get_stat (&shm_info.shm_rss, &shm_info.shm_swp);
458                 shm_info.shm_tot = shm_tot;
459                 shm_info.swap_attempts = 0;
460                 shm_info.swap_successes = 0;
461                 err = shm_ids.max_id;
462                 up(&shm_ids.sem);
463                 if(copy_to_user (buf, &shm_info, sizeof(shm_info))) {
464                         err = -EFAULT;
465                         goto out;
466                 }
467
468                 err = err < 0 ? 0 : err;
469                 goto out;
470         }
471         case SHM_STAT:
472         case IPC_STAT:
473         {
474                 struct shmid64_ds tbuf;
475                 int result;
476                 memset(&tbuf, 0, sizeof(tbuf));
477                 shp = shm_lock(shmid);
478                 if(shp==NULL) {
479                         err = -EINVAL;
480                         goto out;
481                 } else if(cmd==SHM_STAT) {
482                         err = -EINVAL;
483                         if (shmid > shm_ids.max_id)
484                                 goto out_unlock;
485                         result = shm_buildid(shmid, shp->shm_perm.seq);
486                 } else {
487                         err = shm_checkid(shp,shmid);
488                         if(err)
489                                 goto out_unlock;
490                         result = 0;
491                 }
492                 err=-EACCES;
493                 if (ipcperms (&shp->shm_perm, S_IRUGO))
494                         goto out_unlock;
495                 err = security_shm_shmctl(shp, cmd);
496                 if (err)
497                         goto out_unlock;
498                 kernel_to_ipc64_perm(&shp->shm_perm, &tbuf.shm_perm);
499                 tbuf.shm_segsz  = shp->shm_segsz;
500                 tbuf.shm_atime  = shp->shm_atim;
501                 tbuf.shm_dtime  = shp->shm_dtim;
502                 tbuf.shm_ctime  = shp->shm_ctim;
503                 tbuf.shm_cpid   = shp->shm_cprid;
504                 tbuf.shm_lpid   = shp->shm_lprid;
505                 if (!is_file_hugepages(shp->shm_file))
506                         tbuf.shm_nattch = shp->shm_nattch;
507                 else
508                         tbuf.shm_nattch = file_count(shp->shm_file) - 1;
509                 shm_unlock(shp);
510                 if(copy_shmid_to_user (buf, &tbuf, version))
511                         err = -EFAULT;
512                 else
513                         err = result;
514                 goto out;
515         }
516         case SHM_LOCK:
517         case SHM_UNLOCK:
518         {
519                 shp = shm_lock(shmid);
520                 if(shp==NULL) {
521                         err = -EINVAL;
522                         goto out;
523                 }
524                 err = shm_checkid(shp,shmid);
525                 if(err)
526                         goto out_unlock;
527
528                 if (!capable(CAP_IPC_LOCK)) {
529                         err = -EPERM;
530                         if (current->euid != shp->shm_perm.uid &&
531                             current->euid != shp->shm_perm.cuid)
532                                 goto out_unlock;
533                         if (cmd == SHM_LOCK &&
534                             !current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur)
535                                 goto out_unlock;
536                 }
537
538                 err = security_shm_shmctl(shp, cmd);
539                 if (err)
540                         goto out_unlock;
541                 
542                 if(cmd==SHM_LOCK) {
543                         struct user_struct * user = current->user;
544                         if (!is_file_hugepages(shp->shm_file)) {
545                                 err = shmem_lock(shp->shm_file, 1, user);
546                                 if (!err) {
547                                         shp->shm_flags |= SHM_LOCKED;
548                                         shp->mlock_user = user;
549                                 }
550                         }
551                 } else if (!is_file_hugepages(shp->shm_file)) {
552                         shmem_lock(shp->shm_file, 0, shp->mlock_user);
553                         shp->shm_flags &= ~SHM_LOCKED;
554                         shp->mlock_user = NULL;
555                 }
556                 shm_unlock(shp);
557                 goto out;
558         }
559         case IPC_RMID:
560         {
561                 /*
562                  *      We cannot simply remove the file. The SVID states
563                  *      that the block remains until the last person
564                  *      detaches from it, then is deleted. A shmat() on
565                  *      an RMID segment is legal in older Linux and if 
566                  *      we change it apps break...
567                  *
568                  *      Instead we set a destroyed flag, and then blow
569                  *      the name away when the usage hits zero.
570                  */
571                 down(&shm_ids.sem);
572                 shp = shm_lock(shmid);
573                 err = -EINVAL;
574                 if (shp == NULL) 
575                         goto out_up;
576                 err = shm_checkid(shp, shmid);
577                 if(err)
578                         goto out_unlock_up;
579
580                 if (current->euid != shp->shm_perm.uid &&
581                     current->euid != shp->shm_perm.cuid && 
582                     !capable(CAP_SYS_ADMIN)) {
583                         err=-EPERM;
584                         goto out_unlock_up;
585                 }
586
587                 err = security_shm_shmctl(shp, cmd);
588                 if (err)
589                         goto out_unlock_up;
590
591                 if (shp->shm_nattch){
592                         shp->shm_flags |= SHM_DEST;
593                         /* Do not find it any more */
594                         shp->shm_perm.key = IPC_PRIVATE;
595                         shm_unlock(shp);
596                 } else
597                         shm_destroy (shp);
598                 up(&shm_ids.sem);
599                 goto out;
600         }
601
602         case IPC_SET:
603         {
604                 if (copy_shmid_from_user (&setbuf, buf, version)) {
605                         err = -EFAULT;
606                         goto out;
607                 }
608                 if ((err = audit_ipc_perms(0, setbuf.uid, setbuf.gid, setbuf.mode)))
609                         return err;
610                 down(&shm_ids.sem);
611                 shp = shm_lock(shmid);
612                 err=-EINVAL;
613                 if(shp==NULL)
614                         goto out_up;
615                 err = shm_checkid(shp,shmid);
616                 if(err)
617                         goto out_unlock_up;
618                 err=-EPERM;
619                 if (current->euid != shp->shm_perm.uid &&
620                     current->euid != shp->shm_perm.cuid && 
621                     !capable(CAP_SYS_ADMIN)) {
622                         goto out_unlock_up;
623                 }
624
625                 err = security_shm_shmctl(shp, cmd);
626                 if (err)
627                         goto out_unlock_up;
628                 
629                 shp->shm_perm.uid = setbuf.uid;
630                 shp->shm_perm.gid = setbuf.gid;
631                 shp->shm_flags = (shp->shm_flags & ~S_IRWXUGO)
632                         | (setbuf.mode & S_IRWXUGO);
633                 shp->shm_ctim = get_seconds();
634                 break;
635         }
636
637         default:
638                 err = -EINVAL;
639                 goto out;
640         }
641
642         err = 0;
643 out_unlock_up:
644         shm_unlock(shp);
645 out_up:
646         up(&shm_ids.sem);
647         goto out;
648 out_unlock:
649         shm_unlock(shp);
650 out:
651         return err;
652 }
653
654 /*
655  * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
656  *
657  * NOTE! Despite the name, this is NOT a direct system call entrypoint. The
658  * "raddr" thing points to kernel space, and there has to be a wrapper around
659  * this.
660  */
661 long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr)
662 {
663         struct shmid_kernel *shp;
664         unsigned long addr;
665         unsigned long size;
666         struct file * file;
667         int    err;
668         unsigned long flags;
669         unsigned long prot;
670         unsigned long o_flags;
671         int acc_mode;
672         void *user_addr;
673
674         if (shmid < 0) {
675                 err = -EINVAL;
676                 goto out;
677         } else if ((addr = (ulong)shmaddr)) {
678                 if (addr & (SHMLBA-1)) {
679                         if (shmflg & SHM_RND)
680                                 addr &= ~(SHMLBA-1);       /* round down */
681                         else
682 #ifndef __ARCH_FORCE_SHMLBA
683                                 if (addr & ~PAGE_MASK)
684 #endif
685                                         return -EINVAL;
686                 }
687                 flags = MAP_SHARED | MAP_FIXED;
688         } else {
689                 if ((shmflg & SHM_REMAP))
690                         return -EINVAL;
691
692                 flags = MAP_SHARED;
693         }
694
695         if (shmflg & SHM_RDONLY) {
696                 prot = PROT_READ;
697                 o_flags = O_RDONLY;
698                 acc_mode = S_IRUGO;
699         } else {
700                 prot = PROT_READ | PROT_WRITE;
701                 o_flags = O_RDWR;
702                 acc_mode = S_IRUGO | S_IWUGO;
703         }
704         if (shmflg & SHM_EXEC) {
705                 prot |= PROT_EXEC;
706                 acc_mode |= S_IXUGO;
707         }
708
709         /*
710          * We cannot rely on the fs check since SYSV IPC does have an
711          * additional creator id...
712          */
713         shp = shm_lock(shmid);
714         if(shp == NULL) {
715                 err = -EINVAL;
716                 goto out;
717         }
718         err = shm_checkid(shp,shmid);
719         if (err) {
720                 shm_unlock(shp);
721                 goto out;
722         }
723         if (ipcperms(&shp->shm_perm, acc_mode)) {
724                 shm_unlock(shp);
725                 err = -EACCES;
726                 goto out;
727         }
728
729         err = security_shm_shmat(shp, shmaddr, shmflg);
730         if (err) {
731                 shm_unlock(shp);
732                 return err;
733         }
734                 
735         file = shp->shm_file;
736         size = i_size_read(file->f_dentry->d_inode);
737         shp->shm_nattch++;
738         shm_unlock(shp);
739
740         down_write(&current->mm->mmap_sem);
741         if (addr && !(shmflg & SHM_REMAP)) {
742                 user_addr = ERR_PTR(-EINVAL);
743                 if (find_vma_intersection(current->mm, addr, addr + size))
744                         goto invalid;
745                 /*
746                  * If shm segment goes below stack, make sure there is some
747                  * space left for the stack to grow (at least 4 pages).
748                  */
749                 if (addr < current->mm->start_stack &&
750                     addr > current->mm->start_stack - size - PAGE_SIZE * 5)
751                         goto invalid;
752         }
753                 
754         user_addr = (void*) do_mmap (file, addr, size, prot, flags, 0);
755
756 invalid:
757         up_write(&current->mm->mmap_sem);
758
759         down (&shm_ids.sem);
760         if(!(shp = shm_lock(shmid)))
761                 BUG();
762         shp->shm_nattch--;
763         if(shp->shm_nattch == 0 &&
764            shp->shm_flags & SHM_DEST)
765                 shm_destroy (shp);
766         else
767                 shm_unlock(shp);
768         up (&shm_ids.sem);
769
770         *raddr = (unsigned long) user_addr;
771         err = 0;
772         if (IS_ERR(user_addr))
773                 err = PTR_ERR(user_addr);
774 out:
775         return err;
776 }
777
778 asmlinkage long sys_shmat(int shmid, char __user *shmaddr, int shmflg)
779 {
780         unsigned long ret;
781         long err;
782
783         err = do_shmat(shmid, shmaddr, shmflg, &ret);
784         if (err)
785                 return err;
786         force_successful_syscall_return();
787         return (long)ret;
788 }
789
790 /*
791  * detach and kill segment if marked destroyed.
792  * The work is done in shm_close.
793  */
794 asmlinkage long sys_shmdt(char __user *shmaddr)
795 {
796         struct mm_struct *mm = current->mm;
797         struct vm_area_struct *vma, *next;
798         unsigned long addr = (unsigned long)shmaddr;
799         loff_t size = 0;
800         int retval = -EINVAL;
801
802         down_write(&mm->mmap_sem);
803
804         /*
805          * This function tries to be smart and unmap shm segments that
806          * were modified by partial mlock or munmap calls:
807          * - It first determines the size of the shm segment that should be
808          *   unmapped: It searches for a vma that is backed by shm and that
809          *   started at address shmaddr. It records it's size and then unmaps
810          *   it.
811          * - Then it unmaps all shm vmas that started at shmaddr and that
812          *   are within the initially determined size.
813          * Errors from do_munmap are ignored: the function only fails if
814          * it's called with invalid parameters or if it's called to unmap
815          * a part of a vma. Both calls in this function are for full vmas,
816          * the parameters are directly copied from the vma itself and always
817          * valid - therefore do_munmap cannot fail. (famous last words?)
818          */
819         /*
820          * If it had been mremap()'d, the starting address would not
821          * match the usual checks anyway. So assume all vma's are
822          * above the starting address given.
823          */
824         vma = find_vma(mm, addr);
825
826         while (vma) {
827                 next = vma->vm_next;
828
829                 /*
830                  * Check if the starting address would match, i.e. it's
831                  * a fragment created by mprotect() and/or munmap(), or it
832                  * otherwise it starts at this address with no hassles.
833                  */
834                 if ((vma->vm_ops == &shm_vm_ops || is_vm_hugetlb_page(vma)) &&
835                         (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) {
836
837
838                         size = vma->vm_file->f_dentry->d_inode->i_size;
839                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
840                         /*
841                          * We discovered the size of the shm segment, so
842                          * break out of here and fall through to the next
843                          * loop that uses the size information to stop
844                          * searching for matching vma's.
845                          */
846                         retval = 0;
847                         vma = next;
848                         break;
849                 }
850                 vma = next;
851         }
852
853         /*
854          * We need look no further than the maximum address a fragment
855          * could possibly have landed at. Also cast things to loff_t to
856          * prevent overflows and make comparisions vs. equal-width types.
857          */
858         while (vma && (loff_t)(vma->vm_end - addr) <= size) {
859                 next = vma->vm_next;
860
861                 /* finding a matching vma now does not alter retval */
862                 if ((vma->vm_ops == &shm_vm_ops || is_vm_hugetlb_page(vma)) &&
863                         (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff)
864
865                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
866                 vma = next;
867         }
868
869         up_write(&mm->mmap_sem);
870         return retval;
871 }
872
873 #ifdef CONFIG_PROC_FS
874 static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
875 {
876         struct shmid_kernel *shp = it;
877         char *format;
878
879 #define SMALL_STRING "%10d %10d  %4o %10u %5u %5u  %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
880 #define BIG_STRING   "%10d %10d  %4o %21u %5u %5u  %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
881
882         if (sizeof(size_t) <= sizeof(int))
883                 format = SMALL_STRING;
884         else
885                 format = BIG_STRING;
886         return seq_printf(s, format,
887                           shp->shm_perm.key,
888                           shp->id,
889                           shp->shm_flags,
890                           shp->shm_segsz,
891                           shp->shm_cprid,
892                           shp->shm_lprid,
893                           is_file_hugepages(shp->shm_file) ? (file_count(shp->shm_file) - 1) : shp->shm_nattch,
894                           shp->shm_perm.uid,
895                           shp->shm_perm.gid,
896                           shp->shm_perm.cuid,
897                           shp->shm_perm.cgid,
898                           shp->shm_atim,
899                           shp->shm_dtim,
900                           shp->shm_ctim);
901 }
902 #endif