[PATCH] NOMMU: Make SYSV IPC SHM use ramfs facilities on NOMMU
[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/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         int ret;
161
162         ret = shmem_mmap(file, vma);
163         if (ret == 0) {
164                 vma->vm_ops = &shm_vm_ops;
165                 shm_inc(file->f_dentry->d_inode->i_ino);
166         }
167
168         return ret;
169 }
170
171 static struct file_operations shm_file_operations = {
172         .mmap   = shm_mmap,
173 #ifndef CONFIG_MMU
174         .get_unmapped_area = shmem_get_unmapped_area,
175 #endif
176 };
177
178 static struct vm_operations_struct shm_vm_ops = {
179         .open   = shm_open,     /* callback for a new vm-area open */
180         .close  = shm_close,    /* callback for when the vm-area is released */
181         .nopage = shmem_nopage,
182 #if defined(CONFIG_NUMA) && defined(CONFIG_SHMEM)
183         .set_policy = shmem_set_policy,
184         .get_policy = shmem_get_policy,
185 #endif
186 };
187
188 static int newseg (key_t key, int shmflg, size_t size)
189 {
190         int error;
191         struct shmid_kernel *shp;
192         int numpages = (size + PAGE_SIZE -1) >> PAGE_SHIFT;
193         struct file * file;
194         char name[13];
195         int id;
196
197         if (size < SHMMIN || size > shm_ctlmax)
198                 return -EINVAL;
199
200         if (shm_tot + numpages >= shm_ctlall)
201                 return -ENOSPC;
202
203         shp = ipc_rcu_alloc(sizeof(*shp));
204         if (!shp)
205                 return -ENOMEM;
206
207         shp->shm_perm.key = key;
208         shp->shm_flags = (shmflg & S_IRWXUGO);
209         shp->mlock_user = NULL;
210
211         shp->shm_perm.security = NULL;
212         error = security_shm_alloc(shp);
213         if (error) {
214                 ipc_rcu_putref(shp);
215                 return error;
216         }
217
218         if (shmflg & SHM_HUGETLB) {
219                 /* hugetlb_zero_setup takes care of mlock user accounting */
220                 file = hugetlb_zero_setup(size);
221                 shp->mlock_user = current->user;
222         } else {
223                 int acctflag = VM_ACCOUNT;
224                 /*
225                  * Do not allow no accounting for OVERCOMMIT_NEVER, even
226                  * if it's asked for.
227                  */
228                 if  ((shmflg & SHM_NORESERVE) &&
229                                 sysctl_overcommit_memory != OVERCOMMIT_NEVER)
230                         acctflag = 0;
231                 sprintf (name, "SYSV%08x", key);
232                 file = shmem_file_setup(name, size, acctflag);
233         }
234         error = PTR_ERR(file);
235         if (IS_ERR(file))
236                 goto no_file;
237
238         error = -ENOSPC;
239         id = shm_addid(shp);
240         if(id == -1) 
241                 goto no_id;
242
243         shp->shm_cprid = current->tgid;
244         shp->shm_lprid = 0;
245         shp->shm_atim = shp->shm_dtim = 0;
246         shp->shm_ctim = get_seconds();
247         shp->shm_segsz = size;
248         shp->shm_nattch = 0;
249         shp->id = shm_buildid(id,shp->shm_perm.seq);
250         shp->shm_file = file;
251         file->f_dentry->d_inode->i_ino = shp->id;
252
253         /* Hugetlb ops would have already been assigned. */
254         if (!(shmflg & SHM_HUGETLB))
255                 file->f_op = &shm_file_operations;
256
257         shm_tot += numpages;
258         shm_unlock(shp);
259         return shp->id;
260
261 no_id:
262         fput(file);
263 no_file:
264         security_shm_free(shp);
265         ipc_rcu_putref(shp);
266         return error;
267 }
268
269 asmlinkage long sys_shmget (key_t key, size_t size, int shmflg)
270 {
271         struct shmid_kernel *shp;
272         int err, id = 0;
273
274         down(&shm_ids.sem);
275         if (key == IPC_PRIVATE) {
276                 err = newseg(key, shmflg, size);
277         } else if ((id = ipc_findkey(&shm_ids, key)) == -1) {
278                 if (!(shmflg & IPC_CREAT))
279                         err = -ENOENT;
280                 else
281                         err = newseg(key, shmflg, size);
282         } else if ((shmflg & IPC_CREAT) && (shmflg & IPC_EXCL)) {
283                 err = -EEXIST;
284         } else {
285                 shp = shm_lock(id);
286                 if(shp==NULL)
287                         BUG();
288                 if (shp->shm_segsz < size)
289                         err = -EINVAL;
290                 else if (ipcperms(&shp->shm_perm, shmflg))
291                         err = -EACCES;
292                 else {
293                         int shmid = shm_buildid(id, shp->shm_perm.seq);
294                         err = security_shm_associate(shp, shmflg);
295                         if (!err)
296                                 err = shmid;
297                 }
298                 shm_unlock(shp);
299         }
300         up(&shm_ids.sem);
301
302         return err;
303 }
304
305 static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version)
306 {
307         switch(version) {
308         case IPC_64:
309                 return copy_to_user(buf, in, sizeof(*in));
310         case IPC_OLD:
311             {
312                 struct shmid_ds out;
313
314                 ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
315                 out.shm_segsz   = in->shm_segsz;
316                 out.shm_atime   = in->shm_atime;
317                 out.shm_dtime   = in->shm_dtime;
318                 out.shm_ctime   = in->shm_ctime;
319                 out.shm_cpid    = in->shm_cpid;
320                 out.shm_lpid    = in->shm_lpid;
321                 out.shm_nattch  = in->shm_nattch;
322
323                 return copy_to_user(buf, &out, sizeof(out));
324             }
325         default:
326                 return -EINVAL;
327         }
328 }
329
330 struct shm_setbuf {
331         uid_t   uid;
332         gid_t   gid;
333         mode_t  mode;
334 };      
335
336 static inline unsigned long copy_shmid_from_user(struct shm_setbuf *out, void __user *buf, int version)
337 {
338         switch(version) {
339         case IPC_64:
340             {
341                 struct shmid64_ds tbuf;
342
343                 if (copy_from_user(&tbuf, buf, sizeof(tbuf)))
344                         return -EFAULT;
345
346                 out->uid        = tbuf.shm_perm.uid;
347                 out->gid        = tbuf.shm_perm.gid;
348                 out->mode       = tbuf.shm_flags;
349
350                 return 0;
351             }
352         case IPC_OLD:
353             {
354                 struct shmid_ds tbuf_old;
355
356                 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
357                         return -EFAULT;
358
359                 out->uid        = tbuf_old.shm_perm.uid;
360                 out->gid        = tbuf_old.shm_perm.gid;
361                 out->mode       = tbuf_old.shm_flags;
362
363                 return 0;
364             }
365         default:
366                 return -EINVAL;
367         }
368 }
369
370 static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminfo64 *in, int version)
371 {
372         switch(version) {
373         case IPC_64:
374                 return copy_to_user(buf, in, sizeof(*in));
375         case IPC_OLD:
376             {
377                 struct shminfo out;
378
379                 if(in->shmmax > INT_MAX)
380                         out.shmmax = INT_MAX;
381                 else
382                         out.shmmax = (int)in->shmmax;
383
384                 out.shmmin      = in->shmmin;
385                 out.shmmni      = in->shmmni;
386                 out.shmseg      = in->shmseg;
387                 out.shmall      = in->shmall; 
388
389                 return copy_to_user(buf, &out, sizeof(out));
390             }
391         default:
392                 return -EINVAL;
393         }
394 }
395
396 static void shm_get_stat(unsigned long *rss, unsigned long *swp) 
397 {
398         int i;
399
400         *rss = 0;
401         *swp = 0;
402
403         for (i = 0; i <= shm_ids.max_id; i++) {
404                 struct shmid_kernel *shp;
405                 struct inode *inode;
406
407                 shp = shm_get(i);
408                 if(!shp)
409                         continue;
410
411                 inode = shp->shm_file->f_dentry->d_inode;
412
413                 if (is_file_hugepages(shp->shm_file)) {
414                         struct address_space *mapping = inode->i_mapping;
415                         *rss += (HPAGE_SIZE/PAGE_SIZE)*mapping->nrpages;
416                 } else {
417                         struct shmem_inode_info *info = SHMEM_I(inode);
418                         spin_lock(&info->lock);
419                         *rss += inode->i_mapping->nrpages;
420                         *swp += info->swapped;
421                         spin_unlock(&info->lock);
422                 }
423         }
424 }
425
426 asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds __user *buf)
427 {
428         struct shm_setbuf setbuf;
429         struct shmid_kernel *shp;
430         int err, version;
431
432         if (cmd < 0 || shmid < 0) {
433                 err = -EINVAL;
434                 goto out;
435         }
436
437         version = ipc_parse_version(&cmd);
438
439         switch (cmd) { /* replace with proc interface ? */
440         case IPC_INFO:
441         {
442                 struct shminfo64 shminfo;
443
444                 err = security_shm_shmctl(NULL, cmd);
445                 if (err)
446                         return err;
447
448                 memset(&shminfo,0,sizeof(shminfo));
449                 shminfo.shmmni = shminfo.shmseg = shm_ctlmni;
450                 shminfo.shmmax = shm_ctlmax;
451                 shminfo.shmall = shm_ctlall;
452
453                 shminfo.shmmin = SHMMIN;
454                 if(copy_shminfo_to_user (buf, &shminfo, version))
455                         return -EFAULT;
456                 /* reading a integer is always atomic */
457                 err= shm_ids.max_id;
458                 if(err<0)
459                         err = 0;
460                 goto out;
461         }
462         case SHM_INFO:
463         {
464                 struct shm_info shm_info;
465
466                 err = security_shm_shmctl(NULL, cmd);
467                 if (err)
468                         return err;
469
470                 memset(&shm_info,0,sizeof(shm_info));
471                 down(&shm_ids.sem);
472                 shm_info.used_ids = shm_ids.in_use;
473                 shm_get_stat (&shm_info.shm_rss, &shm_info.shm_swp);
474                 shm_info.shm_tot = shm_tot;
475                 shm_info.swap_attempts = 0;
476                 shm_info.swap_successes = 0;
477                 err = shm_ids.max_id;
478                 up(&shm_ids.sem);
479                 if(copy_to_user (buf, &shm_info, sizeof(shm_info))) {
480                         err = -EFAULT;
481                         goto out;
482                 }
483
484                 err = err < 0 ? 0 : err;
485                 goto out;
486         }
487         case SHM_STAT:
488         case IPC_STAT:
489         {
490                 struct shmid64_ds tbuf;
491                 int result;
492                 memset(&tbuf, 0, sizeof(tbuf));
493                 shp = shm_lock(shmid);
494                 if(shp==NULL) {
495                         err = -EINVAL;
496                         goto out;
497                 } else if(cmd==SHM_STAT) {
498                         err = -EINVAL;
499                         if (shmid > shm_ids.max_id)
500                                 goto out_unlock;
501                         result = shm_buildid(shmid, shp->shm_perm.seq);
502                 } else {
503                         err = shm_checkid(shp,shmid);
504                         if(err)
505                                 goto out_unlock;
506                         result = 0;
507                 }
508                 err=-EACCES;
509                 if (ipcperms (&shp->shm_perm, S_IRUGO))
510                         goto out_unlock;
511                 err = security_shm_shmctl(shp, cmd);
512                 if (err)
513                         goto out_unlock;
514                 kernel_to_ipc64_perm(&shp->shm_perm, &tbuf.shm_perm);
515                 tbuf.shm_segsz  = shp->shm_segsz;
516                 tbuf.shm_atime  = shp->shm_atim;
517                 tbuf.shm_dtime  = shp->shm_dtim;
518                 tbuf.shm_ctime  = shp->shm_ctim;
519                 tbuf.shm_cpid   = shp->shm_cprid;
520                 tbuf.shm_lpid   = shp->shm_lprid;
521                 if (!is_file_hugepages(shp->shm_file))
522                         tbuf.shm_nattch = shp->shm_nattch;
523                 else
524                         tbuf.shm_nattch = file_count(shp->shm_file) - 1;
525                 shm_unlock(shp);
526                 if(copy_shmid_to_user (buf, &tbuf, version))
527                         err = -EFAULT;
528                 else
529                         err = result;
530                 goto out;
531         }
532         case SHM_LOCK:
533         case SHM_UNLOCK:
534         {
535                 shp = shm_lock(shmid);
536                 if(shp==NULL) {
537                         err = -EINVAL;
538                         goto out;
539                 }
540                 err = shm_checkid(shp,shmid);
541                 if(err)
542                         goto out_unlock;
543
544                 if (!capable(CAP_IPC_LOCK)) {
545                         err = -EPERM;
546                         if (current->euid != shp->shm_perm.uid &&
547                             current->euid != shp->shm_perm.cuid)
548                                 goto out_unlock;
549                         if (cmd == SHM_LOCK &&
550                             !current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur)
551                                 goto out_unlock;
552                 }
553
554                 err = security_shm_shmctl(shp, cmd);
555                 if (err)
556                         goto out_unlock;
557                 
558                 if(cmd==SHM_LOCK) {
559                         struct user_struct * user = current->user;
560                         if (!is_file_hugepages(shp->shm_file)) {
561                                 err = shmem_lock(shp->shm_file, 1, user);
562                                 if (!err) {
563                                         shp->shm_flags |= SHM_LOCKED;
564                                         shp->mlock_user = user;
565                                 }
566                         }
567                 } else if (!is_file_hugepages(shp->shm_file)) {
568                         shmem_lock(shp->shm_file, 0, shp->mlock_user);
569                         shp->shm_flags &= ~SHM_LOCKED;
570                         shp->mlock_user = NULL;
571                 }
572                 shm_unlock(shp);
573                 goto out;
574         }
575         case IPC_RMID:
576         {
577                 /*
578                  *      We cannot simply remove the file. The SVID states
579                  *      that the block remains until the last person
580                  *      detaches from it, then is deleted. A shmat() on
581                  *      an RMID segment is legal in older Linux and if 
582                  *      we change it apps break...
583                  *
584                  *      Instead we set a destroyed flag, and then blow
585                  *      the name away when the usage hits zero.
586                  */
587                 down(&shm_ids.sem);
588                 shp = shm_lock(shmid);
589                 err = -EINVAL;
590                 if (shp == NULL) 
591                         goto out_up;
592                 err = shm_checkid(shp, shmid);
593                 if(err)
594                         goto out_unlock_up;
595
596                 if (current->euid != shp->shm_perm.uid &&
597                     current->euid != shp->shm_perm.cuid && 
598                     !capable(CAP_SYS_ADMIN)) {
599                         err=-EPERM;
600                         goto out_unlock_up;
601                 }
602
603                 err = security_shm_shmctl(shp, cmd);
604                 if (err)
605                         goto out_unlock_up;
606
607                 if (shp->shm_nattch){
608                         shp->shm_flags |= SHM_DEST;
609                         /* Do not find it any more */
610                         shp->shm_perm.key = IPC_PRIVATE;
611                         shm_unlock(shp);
612                 } else
613                         shm_destroy (shp);
614                 up(&shm_ids.sem);
615                 goto out;
616         }
617
618         case IPC_SET:
619         {
620                 if (copy_shmid_from_user (&setbuf, buf, version)) {
621                         err = -EFAULT;
622                         goto out;
623                 }
624                 if ((err = audit_ipc_perms(0, setbuf.uid, setbuf.gid, setbuf.mode)))
625                         return err;
626                 down(&shm_ids.sem);
627                 shp = shm_lock(shmid);
628                 err=-EINVAL;
629                 if(shp==NULL)
630                         goto out_up;
631                 err = shm_checkid(shp,shmid);
632                 if(err)
633                         goto out_unlock_up;
634                 err=-EPERM;
635                 if (current->euid != shp->shm_perm.uid &&
636                     current->euid != shp->shm_perm.cuid && 
637                     !capable(CAP_SYS_ADMIN)) {
638                         goto out_unlock_up;
639                 }
640
641                 err = security_shm_shmctl(shp, cmd);
642                 if (err)
643                         goto out_unlock_up;
644                 
645                 shp->shm_perm.uid = setbuf.uid;
646                 shp->shm_perm.gid = setbuf.gid;
647                 shp->shm_flags = (shp->shm_flags & ~S_IRWXUGO)
648                         | (setbuf.mode & S_IRWXUGO);
649                 shp->shm_ctim = get_seconds();
650                 break;
651         }
652
653         default:
654                 err = -EINVAL;
655                 goto out;
656         }
657
658         err = 0;
659 out_unlock_up:
660         shm_unlock(shp);
661 out_up:
662         up(&shm_ids.sem);
663         goto out;
664 out_unlock:
665         shm_unlock(shp);
666 out:
667         return err;
668 }
669
670 /*
671  * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
672  *
673  * NOTE! Despite the name, this is NOT a direct system call entrypoint. The
674  * "raddr" thing points to kernel space, and there has to be a wrapper around
675  * this.
676  */
677 long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr)
678 {
679         struct shmid_kernel *shp;
680         unsigned long addr;
681         unsigned long size;
682         struct file * file;
683         int    err;
684         unsigned long flags;
685         unsigned long prot;
686         unsigned long o_flags;
687         int acc_mode;
688         void *user_addr;
689
690         if (shmid < 0) {
691                 err = -EINVAL;
692                 goto out;
693         } else if ((addr = (ulong)shmaddr)) {
694                 if (addr & (SHMLBA-1)) {
695                         if (shmflg & SHM_RND)
696                                 addr &= ~(SHMLBA-1);       /* round down */
697                         else
698 #ifndef __ARCH_FORCE_SHMLBA
699                                 if (addr & ~PAGE_MASK)
700 #endif
701                                         return -EINVAL;
702                 }
703                 flags = MAP_SHARED | MAP_FIXED;
704         } else {
705                 if ((shmflg & SHM_REMAP))
706                         return -EINVAL;
707
708                 flags = MAP_SHARED;
709         }
710
711         if (shmflg & SHM_RDONLY) {
712                 prot = PROT_READ;
713                 o_flags = O_RDONLY;
714                 acc_mode = S_IRUGO;
715         } else {
716                 prot = PROT_READ | PROT_WRITE;
717                 o_flags = O_RDWR;
718                 acc_mode = S_IRUGO | S_IWUGO;
719         }
720         if (shmflg & SHM_EXEC) {
721                 prot |= PROT_EXEC;
722                 acc_mode |= S_IXUGO;
723         }
724
725         /*
726          * We cannot rely on the fs check since SYSV IPC does have an
727          * additional creator id...
728          */
729         shp = shm_lock(shmid);
730         if(shp == NULL) {
731                 err = -EINVAL;
732                 goto out;
733         }
734         err = shm_checkid(shp,shmid);
735         if (err) {
736                 shm_unlock(shp);
737                 goto out;
738         }
739         if (ipcperms(&shp->shm_perm, acc_mode)) {
740                 shm_unlock(shp);
741                 err = -EACCES;
742                 goto out;
743         }
744
745         err = security_shm_shmat(shp, shmaddr, shmflg);
746         if (err) {
747                 shm_unlock(shp);
748                 return err;
749         }
750                 
751         file = shp->shm_file;
752         size = i_size_read(file->f_dentry->d_inode);
753         shp->shm_nattch++;
754         shm_unlock(shp);
755
756         down_write(&current->mm->mmap_sem);
757         if (addr && !(shmflg & SHM_REMAP)) {
758                 user_addr = ERR_PTR(-EINVAL);
759                 if (find_vma_intersection(current->mm, addr, addr + size))
760                         goto invalid;
761                 /*
762                  * If shm segment goes below stack, make sure there is some
763                  * space left for the stack to grow (at least 4 pages).
764                  */
765                 if (addr < current->mm->start_stack &&
766                     addr > current->mm->start_stack - size - PAGE_SIZE * 5)
767                         goto invalid;
768         }
769                 
770         user_addr = (void*) do_mmap (file, addr, size, prot, flags, 0);
771
772 invalid:
773         up_write(&current->mm->mmap_sem);
774
775         down (&shm_ids.sem);
776         if(!(shp = shm_lock(shmid)))
777                 BUG();
778         shp->shm_nattch--;
779         if(shp->shm_nattch == 0 &&
780            shp->shm_flags & SHM_DEST)
781                 shm_destroy (shp);
782         else
783                 shm_unlock(shp);
784         up (&shm_ids.sem);
785
786         *raddr = (unsigned long) user_addr;
787         err = 0;
788         if (IS_ERR(user_addr))
789                 err = PTR_ERR(user_addr);
790 out:
791         return err;
792 }
793
794 asmlinkage long sys_shmat(int shmid, char __user *shmaddr, int shmflg)
795 {
796         unsigned long ret;
797         long err;
798
799         err = do_shmat(shmid, shmaddr, shmflg, &ret);
800         if (err)
801                 return err;
802         force_successful_syscall_return();
803         return (long)ret;
804 }
805
806 /*
807  * detach and kill segment if marked destroyed.
808  * The work is done in shm_close.
809  */
810 asmlinkage long sys_shmdt(char __user *shmaddr)
811 {
812         struct mm_struct *mm = current->mm;
813         struct vm_area_struct *vma, *next;
814         unsigned long addr = (unsigned long)shmaddr;
815         loff_t size = 0;
816         int retval = -EINVAL;
817
818         down_write(&mm->mmap_sem);
819
820         /*
821          * This function tries to be smart and unmap shm segments that
822          * were modified by partial mlock or munmap calls:
823          * - It first determines the size of the shm segment that should be
824          *   unmapped: It searches for a vma that is backed by shm and that
825          *   started at address shmaddr. It records it's size and then unmaps
826          *   it.
827          * - Then it unmaps all shm vmas that started at shmaddr and that
828          *   are within the initially determined size.
829          * Errors from do_munmap are ignored: the function only fails if
830          * it's called with invalid parameters or if it's called to unmap
831          * a part of a vma. Both calls in this function are for full vmas,
832          * the parameters are directly copied from the vma itself and always
833          * valid - therefore do_munmap cannot fail. (famous last words?)
834          */
835         /*
836          * If it had been mremap()'d, the starting address would not
837          * match the usual checks anyway. So assume all vma's are
838          * above the starting address given.
839          */
840         vma = find_vma(mm, addr);
841
842         while (vma) {
843                 next = vma->vm_next;
844
845                 /*
846                  * Check if the starting address would match, i.e. it's
847                  * a fragment created by mprotect() and/or munmap(), or it
848                  * otherwise it starts at this address with no hassles.
849                  */
850                 if ((vma->vm_ops == &shm_vm_ops || is_vm_hugetlb_page(vma)) &&
851                         (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) {
852
853
854                         size = vma->vm_file->f_dentry->d_inode->i_size;
855                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
856                         /*
857                          * We discovered the size of the shm segment, so
858                          * break out of here and fall through to the next
859                          * loop that uses the size information to stop
860                          * searching for matching vma's.
861                          */
862                         retval = 0;
863                         vma = next;
864                         break;
865                 }
866                 vma = next;
867         }
868
869         /*
870          * We need look no further than the maximum address a fragment
871          * could possibly have landed at. Also cast things to loff_t to
872          * prevent overflows and make comparisions vs. equal-width types.
873          */
874         while (vma && (loff_t)(vma->vm_end - addr) <= size) {
875                 next = vma->vm_next;
876
877                 /* finding a matching vma now does not alter retval */
878                 if ((vma->vm_ops == &shm_vm_ops || is_vm_hugetlb_page(vma)) &&
879                         (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff)
880
881                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
882                 vma = next;
883         }
884
885         up_write(&mm->mmap_sem);
886         return retval;
887 }
888
889 #ifdef CONFIG_PROC_FS
890 static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
891 {
892         struct shmid_kernel *shp = it;
893         char *format;
894
895 #define SMALL_STRING "%10d %10d  %4o %10u %5u %5u  %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
896 #define BIG_STRING   "%10d %10d  %4o %21u %5u %5u  %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
897
898         if (sizeof(size_t) <= sizeof(int))
899                 format = SMALL_STRING;
900         else
901                 format = BIG_STRING;
902         return seq_printf(s, format,
903                           shp->shm_perm.key,
904                           shp->id,
905                           shp->shm_flags,
906                           shp->shm_segsz,
907                           shp->shm_cprid,
908                           shp->shm_lprid,
909                           is_file_hugepages(shp->shm_file) ? (file_count(shp->shm_file) - 1) : shp->shm_nattch,
910                           shp->shm_perm.uid,
911                           shp->shm_perm.gid,
912                           shp->shm_perm.cuid,
913                           shp->shm_perm.cgid,
914                           shp->shm_atim,
915                           shp->shm_dtim,
916                           shp->shm_ctim);
917 }
918 #endif