[PATCH] sem2mutex: ipc, id.sem
[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/capability.h>
31 #include <linux/ptrace.h>
32 #include <linux/seq_file.h>
33 #include <linux/mutex.h>
34
35 #include <asm/uaccess.h>
36
37 #include "util.h"
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.mutex 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         mutex_lock(&shm_ids.mutex);
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_perm.mode & SHM_DEST)
152                 shm_destroy (shp);
153         else
154                 shm_unlock(shp);
155         mutex_unlock(&shm_ids.mutex);
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_perm.mode = (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         mutex_lock(&shm_ids.mutex);
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         mutex_unlock(&shm_ids.mutex);
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_perm.mode;
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_perm.mode;
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                 mutex_lock(&shm_ids.mutex);
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                 mutex_unlock(&shm_ids.mutex);
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_perm.mode |= 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_perm.mode &= ~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                 mutex_lock(&shm_ids.mutex);
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_perm.mode |= 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                 mutex_unlock(&shm_ids.mutex);
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                 mutex_lock(&shm_ids.mutex);
625                 shp = shm_lock(shmid);
626                 err=-EINVAL;
627                 if(shp==NULL)
628                         goto out_up;
629                 if ((err = audit_ipc_perms(0, setbuf.uid, setbuf.gid,
630                                         setbuf.mode, &(shp->shm_perm))))
631                         goto out_unlock_up;
632                 err = shm_checkid(shp,shmid);
633                 if(err)
634                         goto out_unlock_up;
635                 err=-EPERM;
636                 if (current->euid != shp->shm_perm.uid &&
637                     current->euid != shp->shm_perm.cuid && 
638                     !capable(CAP_SYS_ADMIN)) {
639                         goto out_unlock_up;
640                 }
641
642                 err = security_shm_shmctl(shp, cmd);
643                 if (err)
644                         goto out_unlock_up;
645                 
646                 shp->shm_perm.uid = setbuf.uid;
647                 shp->shm_perm.gid = setbuf.gid;
648                 shp->shm_perm.mode = (shp->shm_perm.mode & ~S_IRWXUGO)
649                         | (setbuf.mode & S_IRWXUGO);
650                 shp->shm_ctim = get_seconds();
651                 break;
652         }
653
654         default:
655                 err = -EINVAL;
656                 goto out;
657         }
658
659         err = 0;
660 out_unlock_up:
661         shm_unlock(shp);
662 out_up:
663         mutex_unlock(&shm_ids.mutex);
664         goto out;
665 out_unlock:
666         shm_unlock(shp);
667 out:
668         return err;
669 }
670
671 /*
672  * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
673  *
674  * NOTE! Despite the name, this is NOT a direct system call entrypoint. The
675  * "raddr" thing points to kernel space, and there has to be a wrapper around
676  * this.
677  */
678 long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr)
679 {
680         struct shmid_kernel *shp;
681         unsigned long addr;
682         unsigned long size;
683         struct file * file;
684         int    err;
685         unsigned long flags;
686         unsigned long prot;
687         unsigned long o_flags;
688         int acc_mode;
689         void *user_addr;
690
691         if (shmid < 0) {
692                 err = -EINVAL;
693                 goto out;
694         } else if ((addr = (ulong)shmaddr)) {
695                 if (addr & (SHMLBA-1)) {
696                         if (shmflg & SHM_RND)
697                                 addr &= ~(SHMLBA-1);       /* round down */
698                         else
699 #ifndef __ARCH_FORCE_SHMLBA
700                                 if (addr & ~PAGE_MASK)
701 #endif
702                                         return -EINVAL;
703                 }
704                 flags = MAP_SHARED | MAP_FIXED;
705         } else {
706                 if ((shmflg & SHM_REMAP))
707                         return -EINVAL;
708
709                 flags = MAP_SHARED;
710         }
711
712         if (shmflg & SHM_RDONLY) {
713                 prot = PROT_READ;
714                 o_flags = O_RDONLY;
715                 acc_mode = S_IRUGO;
716         } else {
717                 prot = PROT_READ | PROT_WRITE;
718                 o_flags = O_RDWR;
719                 acc_mode = S_IRUGO | S_IWUGO;
720         }
721         if (shmflg & SHM_EXEC) {
722                 prot |= PROT_EXEC;
723                 acc_mode |= S_IXUGO;
724         }
725
726         /*
727          * We cannot rely on the fs check since SYSV IPC does have an
728          * additional creator id...
729          */
730         shp = shm_lock(shmid);
731         if(shp == NULL) {
732                 err = -EINVAL;
733                 goto out;
734         }
735         err = shm_checkid(shp,shmid);
736         if (err) {
737                 shm_unlock(shp);
738                 goto out;
739         }
740         if (ipcperms(&shp->shm_perm, acc_mode)) {
741                 shm_unlock(shp);
742                 err = -EACCES;
743                 goto out;
744         }
745
746         err = security_shm_shmat(shp, shmaddr, shmflg);
747         if (err) {
748                 shm_unlock(shp);
749                 return err;
750         }
751                 
752         file = shp->shm_file;
753         size = i_size_read(file->f_dentry->d_inode);
754         shp->shm_nattch++;
755         shm_unlock(shp);
756
757         down_write(&current->mm->mmap_sem);
758         if (addr && !(shmflg & SHM_REMAP)) {
759                 user_addr = ERR_PTR(-EINVAL);
760                 if (find_vma_intersection(current->mm, addr, addr + size))
761                         goto invalid;
762                 /*
763                  * If shm segment goes below stack, make sure there is some
764                  * space left for the stack to grow (at least 4 pages).
765                  */
766                 if (addr < current->mm->start_stack &&
767                     addr > current->mm->start_stack - size - PAGE_SIZE * 5)
768                         goto invalid;
769         }
770                 
771         user_addr = (void*) do_mmap (file, addr, size, prot, flags, 0);
772
773 invalid:
774         up_write(&current->mm->mmap_sem);
775
776         mutex_lock(&shm_ids.mutex);
777         if(!(shp = shm_lock(shmid)))
778                 BUG();
779         shp->shm_nattch--;
780         if(shp->shm_nattch == 0 &&
781            shp->shm_perm.mode & SHM_DEST)
782                 shm_destroy (shp);
783         else
784                 shm_unlock(shp);
785         mutex_unlock(&shm_ids.mutex);
786
787         *raddr = (unsigned long) user_addr;
788         err = 0;
789         if (IS_ERR(user_addr))
790                 err = PTR_ERR(user_addr);
791 out:
792         return err;
793 }
794
795 asmlinkage long sys_shmat(int shmid, char __user *shmaddr, int shmflg)
796 {
797         unsigned long ret;
798         long err;
799
800         err = do_shmat(shmid, shmaddr, shmflg, &ret);
801         if (err)
802                 return err;
803         force_successful_syscall_return();
804         return (long)ret;
805 }
806
807 /*
808  * detach and kill segment if marked destroyed.
809  * The work is done in shm_close.
810  */
811 asmlinkage long sys_shmdt(char __user *shmaddr)
812 {
813         struct mm_struct *mm = current->mm;
814         struct vm_area_struct *vma, *next;
815         unsigned long addr = (unsigned long)shmaddr;
816         loff_t size = 0;
817         int retval = -EINVAL;
818
819         if (addr & ~PAGE_MASK)
820                 return retval;
821
822         down_write(&mm->mmap_sem);
823
824         /*
825          * This function tries to be smart and unmap shm segments that
826          * were modified by partial mlock or munmap calls:
827          * - It first determines the size of the shm segment that should be
828          *   unmapped: It searches for a vma that is backed by shm and that
829          *   started at address shmaddr. It records it's size and then unmaps
830          *   it.
831          * - Then it unmaps all shm vmas that started at shmaddr and that
832          *   are within the initially determined size.
833          * Errors from do_munmap are ignored: the function only fails if
834          * it's called with invalid parameters or if it's called to unmap
835          * a part of a vma. Both calls in this function are for full vmas,
836          * the parameters are directly copied from the vma itself and always
837          * valid - therefore do_munmap cannot fail. (famous last words?)
838          */
839         /*
840          * If it had been mremap()'d, the starting address would not
841          * match the usual checks anyway. So assume all vma's are
842          * above the starting address given.
843          */
844         vma = find_vma(mm, addr);
845
846         while (vma) {
847                 next = vma->vm_next;
848
849                 /*
850                  * Check if the starting address would match, i.e. it's
851                  * a fragment created by mprotect() and/or munmap(), or it
852                  * otherwise it starts at this address with no hassles.
853                  */
854                 if ((vma->vm_ops == &shm_vm_ops || is_vm_hugetlb_page(vma)) &&
855                         (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) {
856
857
858                         size = vma->vm_file->f_dentry->d_inode->i_size;
859                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
860                         /*
861                          * We discovered the size of the shm segment, so
862                          * break out of here and fall through to the next
863                          * loop that uses the size information to stop
864                          * searching for matching vma's.
865                          */
866                         retval = 0;
867                         vma = next;
868                         break;
869                 }
870                 vma = next;
871         }
872
873         /*
874          * We need look no further than the maximum address a fragment
875          * could possibly have landed at. Also cast things to loff_t to
876          * prevent overflows and make comparisions vs. equal-width types.
877          */
878         size = PAGE_ALIGN(size);
879         while (vma && (loff_t)(vma->vm_end - addr) <= size) {
880                 next = vma->vm_next;
881
882                 /* finding a matching vma now does not alter retval */
883                 if ((vma->vm_ops == &shm_vm_ops || is_vm_hugetlb_page(vma)) &&
884                         (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff)
885
886                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
887                 vma = next;
888         }
889
890         up_write(&mm->mmap_sem);
891         return retval;
892 }
893
894 #ifdef CONFIG_PROC_FS
895 static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
896 {
897         struct shmid_kernel *shp = it;
898         char *format;
899
900 #define SMALL_STRING "%10d %10d  %4o %10u %5u %5u  %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
901 #define BIG_STRING   "%10d %10d  %4o %21u %5u %5u  %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
902
903         if (sizeof(size_t) <= sizeof(int))
904                 format = SMALL_STRING;
905         else
906                 format = BIG_STRING;
907         return seq_printf(s, format,
908                           shp->shm_perm.key,
909                           shp->id,
910                           shp->shm_perm.mode,
911                           shp->shm_segsz,
912                           shp->shm_cprid,
913                           shp->shm_lprid,
914                           is_file_hugepages(shp->shm_file) ? (file_count(shp->shm_file) - 1) : shp->shm_nattch,
915                           shp->shm_perm.uid,
916                           shp->shm_perm.gid,
917                           shp->shm_perm.cuid,
918                           shp->shm_perm.cgid,
919                           shp->shm_atim,
920                           shp->shm_dtim,
921                           shp->shm_ctim);
922 }
923 #endif