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