[PATCH] ipc: expand shm_flags
[linux-2.6.git] / ipc / shm.c
1 /*
2  * linux/ipc/shm.c
3  * Copyright (C) 1992, 1993 Krishna Balasubramanian
4  *       Many improvements/fixes by Bruno Haible.
5  * Replaced `struct shm_desc' by `struct vm_area_struct', July 1994.
6  * Fixed the shm swap deallocation (shm_unuse()), August 1998 Andrea Arcangeli.
7  *
8  * /proc/sysvipc/shm support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
9  * BIGMEM support, Andrea Arcangeli <andrea@suse.de>
10  * SMP thread shm, Jean-Luc Boyard <jean-luc.boyard@siemens.fr>
11  * HIGHMEM support, Ingo Molnar <mingo@redhat.com>
12  * Make shmmax, shmall, shmmni sysctl'able, Christoph Rohland <cr@sap.com>
13  * Shared /dev/zero support, Kanoj Sarcar <kanoj@sgi.com>
14  * Move the mm functionality over to mm/shmem.c, Christoph Rohland <cr@sap.com>
15  *
16  */
17
18 #include <linux/config.h>
19 #include <linux/slab.h>
20 #include <linux/mm.h>
21 #include <linux/hugetlb.h>
22 #include <linux/shm.h>
23 #include <linux/init.h>
24 #include <linux/file.h>
25 #include <linux/mman.h>
26 #include <linux/shmem_fs.h>
27 #include <linux/security.h>
28 #include <linux/syscalls.h>
29 #include <linux/audit.h>
30 #include <linux/ptrace.h>
31 #include <linux/seq_file.h>
32
33 #include <asm/uaccess.h>
34
35 #include "util.h"
36
37 static struct file_operations shm_file_operations;
38 static struct vm_operations_struct shm_vm_ops;
39
40 static struct ipc_ids shm_ids;
41
42 #define shm_lock(id)    ((struct shmid_kernel*)ipc_lock(&shm_ids,id))
43 #define shm_unlock(shp) ipc_unlock(&(shp)->shm_perm)
44 #define shm_get(id)     ((struct shmid_kernel*)ipc_get(&shm_ids,id))
45 #define shm_buildid(id, seq) \
46         ipc_buildid(&shm_ids, id, seq)
47
48 static int newseg (key_t key, int shmflg, size_t size);
49 static void shm_open (struct vm_area_struct *shmd);
50 static void shm_close (struct vm_area_struct *shmd);
51 #ifdef CONFIG_PROC_FS
52 static int sysvipc_shm_proc_show(struct seq_file *s, void *it);
53 #endif
54
55 size_t  shm_ctlmax = SHMMAX;
56 size_t  shm_ctlall = SHMALL;
57 int     shm_ctlmni = SHMMNI;
58
59 static int shm_tot; /* total number of shared memory pages */
60
61 void __init shm_init (void)
62 {
63         ipc_init_ids(&shm_ids, 1);
64         ipc_init_proc_interface("sysvipc/shm",
65                                 "       key      shmid perms       size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime\n",
66                                 &shm_ids,
67                                 sysvipc_shm_proc_show);
68 }
69
70 static inline int shm_checkid(struct shmid_kernel *s, int id)
71 {
72         if (ipc_checkid(&shm_ids,&s->shm_perm,id))
73                 return -EIDRM;
74         return 0;
75 }
76
77 static inline struct shmid_kernel *shm_rmid(int id)
78 {
79         return (struct shmid_kernel *)ipc_rmid(&shm_ids,id);
80 }
81
82 static inline int shm_addid(struct shmid_kernel *shp)
83 {
84         return ipc_addid(&shm_ids, &shp->shm_perm, shm_ctlmni);
85 }
86
87
88
89 static inline void shm_inc (int id) {
90         struct shmid_kernel *shp;
91
92         if(!(shp = shm_lock(id)))
93                 BUG();
94         shp->shm_atim = get_seconds();
95         shp->shm_lprid = current->tgid;
96         shp->shm_nattch++;
97         shm_unlock(shp);
98 }
99
100 /* This is called by fork, once for every shm attach. */
101 static void shm_open (struct vm_area_struct *shmd)
102 {
103         shm_inc (shmd->vm_file->f_dentry->d_inode->i_ino);
104 }
105
106 /*
107  * shm_destroy - free the struct shmid_kernel
108  *
109  * @shp: struct to free
110  *
111  * It has to be called with shp and shm_ids.sem locked,
112  * but returns with shp unlocked and freed.
113  */
114 static void shm_destroy (struct shmid_kernel *shp)
115 {
116         shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT;
117         shm_rmid (shp->id);
118         shm_unlock(shp);
119         if (!is_file_hugepages(shp->shm_file))
120                 shmem_lock(shp->shm_file, 0, shp->mlock_user);
121         else
122                 user_shm_unlock(shp->shm_file->f_dentry->d_inode->i_size,
123                                                 shp->mlock_user);
124         fput (shp->shm_file);
125         security_shm_free(shp);
126         ipc_rcu_putref(shp);
127 }
128
129 /*
130  * remove the attach descriptor shmd.
131  * free memory for segment if it is marked destroyed.
132  * The descriptor has already been removed from the current->mm->mmap list
133  * and will later be kfree()d.
134  */
135 static void shm_close (struct vm_area_struct *shmd)
136 {
137         struct file * file = shmd->vm_file;
138         int id = file->f_dentry->d_inode->i_ino;
139         struct shmid_kernel *shp;
140
141         down (&shm_ids.sem);
142         /* remove from the list of attaches of the shm segment */
143         if(!(shp = shm_lock(id)))
144                 BUG();
145         shp->shm_lprid = current->tgid;
146         shp->shm_dtim = get_seconds();
147         shp->shm_nattch--;
148         if(shp->shm_nattch == 0 &&
149            shp->shm_perm.mode & SHM_DEST)
150                 shm_destroy (shp);
151         else
152                 shm_unlock(shp);
153         up (&shm_ids.sem);
154 }
155
156 static int shm_mmap(struct file * file, struct vm_area_struct * vma)
157 {
158         int ret;
159
160         ret = shmem_mmap(file, vma);
161         if (ret == 0) {
162                 vma->vm_ops = &shm_vm_ops;
163                 shm_inc(file->f_dentry->d_inode->i_ino);
164         }
165
166         return ret;
167 }
168
169 static struct file_operations shm_file_operations = {
170         .mmap   = shm_mmap,
171 #ifndef CONFIG_MMU
172         .get_unmapped_area = shmem_get_unmapped_area,
173 #endif
174 };
175
176 static struct vm_operations_struct shm_vm_ops = {
177         .open   = shm_open,     /* callback for a new vm-area open */
178         .close  = shm_close,    /* callback for when the vm-area is released */
179         .nopage = shmem_nopage,
180 #if defined(CONFIG_NUMA) && defined(CONFIG_SHMEM)
181         .set_policy = shmem_set_policy,
182         .get_policy = shmem_get_policy,
183 #endif
184 };
185
186 static int newseg (key_t key, int shmflg, size_t size)
187 {
188         int error;
189         struct shmid_kernel *shp;
190         int numpages = (size + PAGE_SIZE -1) >> PAGE_SHIFT;
191         struct file * file;
192         char name[13];
193         int id;
194
195         if (size < SHMMIN || size > shm_ctlmax)
196                 return -EINVAL;
197
198         if (shm_tot + numpages >= shm_ctlall)
199                 return -ENOSPC;
200
201         shp = ipc_rcu_alloc(sizeof(*shp));
202         if (!shp)
203                 return -ENOMEM;
204
205         shp->shm_perm.key = key;
206         shp->shm_perm.mode = (shmflg & S_IRWXUGO);
207         shp->mlock_user = NULL;
208
209         shp->shm_perm.security = NULL;
210         error = security_shm_alloc(shp);
211         if (error) {
212                 ipc_rcu_putref(shp);
213                 return error;
214         }
215
216         if (shmflg & SHM_HUGETLB) {
217                 /* hugetlb_zero_setup takes care of mlock user accounting */
218                 file = hugetlb_zero_setup(size);
219                 shp->mlock_user = current->user;
220         } else {
221                 int acctflag = VM_ACCOUNT;
222                 /*
223                  * Do not allow no accounting for OVERCOMMIT_NEVER, even
224                  * if it's asked for.
225                  */
226                 if  ((shmflg & SHM_NORESERVE) &&
227                                 sysctl_overcommit_memory != OVERCOMMIT_NEVER)
228                         acctflag = 0;
229                 sprintf (name, "SYSV%08x", key);
230                 file = shmem_file_setup(name, size, acctflag);
231         }
232         error = PTR_ERR(file);
233         if (IS_ERR(file))
234                 goto no_file;
235
236         error = -ENOSPC;
237         id = shm_addid(shp);
238         if(id == -1) 
239                 goto no_id;
240
241         shp->shm_cprid = current->tgid;
242         shp->shm_lprid = 0;
243         shp->shm_atim = shp->shm_dtim = 0;
244         shp->shm_ctim = get_seconds();
245         shp->shm_segsz = size;
246         shp->shm_nattch = 0;
247         shp->id = shm_buildid(id,shp->shm_perm.seq);
248         shp->shm_file = file;
249         file->f_dentry->d_inode->i_ino = shp->id;
250
251         /* Hugetlb ops would have already been assigned. */
252         if (!(shmflg & SHM_HUGETLB))
253                 file->f_op = &shm_file_operations;
254
255         shm_tot += numpages;
256         shm_unlock(shp);
257         return shp->id;
258
259 no_id:
260         fput(file);
261 no_file:
262         security_shm_free(shp);
263         ipc_rcu_putref(shp);
264         return error;
265 }
266
267 asmlinkage long sys_shmget (key_t key, size_t size, int shmflg)
268 {
269         struct shmid_kernel *shp;
270         int err, id = 0;
271
272         down(&shm_ids.sem);
273         if (key == IPC_PRIVATE) {
274                 err = newseg(key, shmflg, size);
275         } else if ((id = ipc_findkey(&shm_ids, key)) == -1) {
276                 if (!(shmflg & IPC_CREAT))
277                         err = -ENOENT;
278                 else
279                         err = newseg(key, shmflg, size);
280         } else if ((shmflg & IPC_CREAT) && (shmflg & IPC_EXCL)) {
281                 err = -EEXIST;
282         } else {
283                 shp = shm_lock(id);
284                 if(shp==NULL)
285                         BUG();
286                 if (shp->shm_segsz < size)
287                         err = -EINVAL;
288                 else if (ipcperms(&shp->shm_perm, shmflg))
289                         err = -EACCES;
290                 else {
291                         int shmid = shm_buildid(id, shp->shm_perm.seq);
292                         err = security_shm_associate(shp, shmflg);
293                         if (!err)
294                                 err = shmid;
295                 }
296                 shm_unlock(shp);
297         }
298         up(&shm_ids.sem);
299
300         return err;
301 }
302
303 static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version)
304 {
305         switch(version) {
306         case IPC_64:
307                 return copy_to_user(buf, in, sizeof(*in));
308         case IPC_OLD:
309             {
310                 struct shmid_ds out;
311
312                 ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
313                 out.shm_segsz   = in->shm_segsz;
314                 out.shm_atime   = in->shm_atime;
315                 out.shm_dtime   = in->shm_dtime;
316                 out.shm_ctime   = in->shm_ctime;
317                 out.shm_cpid    = in->shm_cpid;
318                 out.shm_lpid    = in->shm_lpid;
319                 out.shm_nattch  = in->shm_nattch;
320
321                 return copy_to_user(buf, &out, sizeof(out));
322             }
323         default:
324                 return -EINVAL;
325         }
326 }
327
328 struct shm_setbuf {
329         uid_t   uid;
330         gid_t   gid;
331         mode_t  mode;
332 };      
333
334 static inline unsigned long copy_shmid_from_user(struct shm_setbuf *out, void __user *buf, int version)
335 {
336         switch(version) {
337         case IPC_64:
338             {
339                 struct shmid64_ds tbuf;
340
341                 if (copy_from_user(&tbuf, buf, sizeof(tbuf)))
342                         return -EFAULT;
343
344                 out->uid        = tbuf.shm_perm.uid;
345                 out->gid        = tbuf.shm_perm.gid;
346                 out->mode       = tbuf.shm_perm.mode;
347
348                 return 0;
349             }
350         case IPC_OLD:
351             {
352                 struct shmid_ds tbuf_old;
353
354                 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
355                         return -EFAULT;
356
357                 out->uid        = tbuf_old.shm_perm.uid;
358                 out->gid        = tbuf_old.shm_perm.gid;
359                 out->mode       = tbuf_old.shm_perm.mode;
360
361                 return 0;
362             }
363         default:
364                 return -EINVAL;
365         }
366 }
367
368 static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminfo64 *in, int version)
369 {
370         switch(version) {
371         case IPC_64:
372                 return copy_to_user(buf, in, sizeof(*in));
373         case IPC_OLD:
374             {
375                 struct shminfo out;
376
377                 if(in->shmmax > INT_MAX)
378                         out.shmmax = INT_MAX;
379                 else
380                         out.shmmax = (int)in->shmmax;
381
382                 out.shmmin      = in->shmmin;
383                 out.shmmni      = in->shmmni;
384                 out.shmseg      = in->shmseg;
385                 out.shmall      = in->shmall; 
386
387                 return copy_to_user(buf, &out, sizeof(out));
388             }
389         default:
390                 return -EINVAL;
391         }
392 }
393
394 static void shm_get_stat(unsigned long *rss, unsigned long *swp) 
395 {
396         int i;
397
398         *rss = 0;
399         *swp = 0;
400
401         for (i = 0; i <= shm_ids.max_id; i++) {
402                 struct shmid_kernel *shp;
403                 struct inode *inode;
404
405                 shp = shm_get(i);
406                 if(!shp)
407                         continue;
408
409                 inode = shp->shm_file->f_dentry->d_inode;
410
411                 if (is_file_hugepages(shp->shm_file)) {
412                         struct address_space *mapping = inode->i_mapping;
413                         *rss += (HPAGE_SIZE/PAGE_SIZE)*mapping->nrpages;
414                 } else {
415                         struct shmem_inode_info *info = SHMEM_I(inode);
416                         spin_lock(&info->lock);
417                         *rss += inode->i_mapping->nrpages;
418                         *swp += info->swapped;
419                         spin_unlock(&info->lock);
420                 }
421         }
422 }
423
424 asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds __user *buf)
425 {
426         struct shm_setbuf setbuf;
427         struct shmid_kernel *shp;
428         int err, version;
429
430         if (cmd < 0 || shmid < 0) {
431                 err = -EINVAL;
432                 goto out;
433         }
434
435         version = ipc_parse_version(&cmd);
436
437         switch (cmd) { /* replace with proc interface ? */
438         case IPC_INFO:
439         {
440                 struct shminfo64 shminfo;
441
442                 err = security_shm_shmctl(NULL, cmd);
443                 if (err)
444                         return err;
445
446                 memset(&shminfo,0,sizeof(shminfo));
447                 shminfo.shmmni = shminfo.shmseg = shm_ctlmni;
448                 shminfo.shmmax = shm_ctlmax;
449                 shminfo.shmall = shm_ctlall;
450
451                 shminfo.shmmin = SHMMIN;
452                 if(copy_shminfo_to_user (buf, &shminfo, version))
453                         return -EFAULT;
454                 /* reading a integer is always atomic */
455                 err= shm_ids.max_id;
456                 if(err<0)
457                         err = 0;
458                 goto out;
459         }
460         case SHM_INFO:
461         {
462                 struct shm_info shm_info;
463
464                 err = security_shm_shmctl(NULL, cmd);
465                 if (err)
466                         return err;
467
468                 memset(&shm_info,0,sizeof(shm_info));
469                 down(&shm_ids.sem);
470                 shm_info.used_ids = shm_ids.in_use;
471                 shm_get_stat (&shm_info.shm_rss, &shm_info.shm_swp);
472                 shm_info.shm_tot = shm_tot;
473                 shm_info.swap_attempts = 0;
474                 shm_info.swap_successes = 0;
475                 err = shm_ids.max_id;
476                 up(&shm_ids.sem);
477                 if(copy_to_user (buf, &shm_info, sizeof(shm_info))) {
478                         err = -EFAULT;
479                         goto out;
480                 }
481
482                 err = err < 0 ? 0 : err;
483                 goto out;
484         }
485         case SHM_STAT:
486         case IPC_STAT:
487         {
488                 struct shmid64_ds tbuf;
489                 int result;
490                 memset(&tbuf, 0, sizeof(tbuf));
491                 shp = shm_lock(shmid);
492                 if(shp==NULL) {
493                         err = -EINVAL;
494                         goto out;
495                 } else if(cmd==SHM_STAT) {
496                         err = -EINVAL;
497                         if (shmid > shm_ids.max_id)
498                                 goto out_unlock;
499                         result = shm_buildid(shmid, shp->shm_perm.seq);
500                 } else {
501                         err = shm_checkid(shp,shmid);
502                         if(err)
503                                 goto out_unlock;
504                         result = 0;
505                 }
506                 err=-EACCES;
507                 if (ipcperms (&shp->shm_perm, S_IRUGO))
508                         goto out_unlock;
509                 err = security_shm_shmctl(shp, cmd);
510                 if (err)
511                         goto out_unlock;
512                 kernel_to_ipc64_perm(&shp->shm_perm, &tbuf.shm_perm);
513                 tbuf.shm_segsz  = shp->shm_segsz;
514                 tbuf.shm_atime  = shp->shm_atim;
515                 tbuf.shm_dtime  = shp->shm_dtim;
516                 tbuf.shm_ctime  = shp->shm_ctim;
517                 tbuf.shm_cpid   = shp->shm_cprid;
518                 tbuf.shm_lpid   = shp->shm_lprid;
519                 if (!is_file_hugepages(shp->shm_file))
520                         tbuf.shm_nattch = shp->shm_nattch;
521                 else
522                         tbuf.shm_nattch = file_count(shp->shm_file) - 1;
523                 shm_unlock(shp);
524                 if(copy_shmid_to_user (buf, &tbuf, version))
525                         err = -EFAULT;
526                 else
527                         err = result;
528                 goto out;
529         }
530         case SHM_LOCK:
531         case SHM_UNLOCK:
532         {
533                 shp = shm_lock(shmid);
534                 if(shp==NULL) {
535                         err = -EINVAL;
536                         goto out;
537                 }
538                 err = shm_checkid(shp,shmid);
539                 if(err)
540                         goto out_unlock;
541
542                 if (!capable(CAP_IPC_LOCK)) {
543                         err = -EPERM;
544                         if (current->euid != shp->shm_perm.uid &&
545                             current->euid != shp->shm_perm.cuid)
546                                 goto out_unlock;
547                         if (cmd == SHM_LOCK &&
548                             !current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur)
549                                 goto out_unlock;
550                 }
551
552                 err = security_shm_shmctl(shp, cmd);
553                 if (err)
554                         goto out_unlock;
555                 
556                 if(cmd==SHM_LOCK) {
557                         struct user_struct * user = current->user;
558                         if (!is_file_hugepages(shp->shm_file)) {
559                                 err = shmem_lock(shp->shm_file, 1, user);
560                                 if (!err) {
561                                         shp->shm_perm.mode |= SHM_LOCKED;
562                                         shp->mlock_user = user;
563                                 }
564                         }
565                 } else if (!is_file_hugepages(shp->shm_file)) {
566                         shmem_lock(shp->shm_file, 0, shp->mlock_user);
567                         shp->shm_perm.mode &= ~SHM_LOCKED;
568                         shp->mlock_user = NULL;
569                 }
570                 shm_unlock(shp);
571                 goto out;
572         }
573         case IPC_RMID:
574         {
575                 /*
576                  *      We cannot simply remove the file. The SVID states
577                  *      that the block remains until the last person
578                  *      detaches from it, then is deleted. A shmat() on
579                  *      an RMID segment is legal in older Linux and if 
580                  *      we change it apps break...
581                  *
582                  *      Instead we set a destroyed flag, and then blow
583                  *      the name away when the usage hits zero.
584                  */
585                 down(&shm_ids.sem);
586                 shp = shm_lock(shmid);
587                 err = -EINVAL;
588                 if (shp == NULL) 
589                         goto out_up;
590                 err = shm_checkid(shp, shmid);
591                 if(err)
592                         goto out_unlock_up;
593
594                 if (current->euid != shp->shm_perm.uid &&
595                     current->euid != shp->shm_perm.cuid && 
596                     !capable(CAP_SYS_ADMIN)) {
597                         err=-EPERM;
598                         goto out_unlock_up;
599                 }
600
601                 err = security_shm_shmctl(shp, cmd);
602                 if (err)
603                         goto out_unlock_up;
604
605                 if (shp->shm_nattch){
606                         shp->shm_perm.mode |= SHM_DEST;
607                         /* Do not find it any more */
608                         shp->shm_perm.key = IPC_PRIVATE;
609                         shm_unlock(shp);
610                 } else
611                         shm_destroy (shp);
612                 up(&shm_ids.sem);
613                 goto out;
614         }
615
616         case IPC_SET:
617         {
618                 if (copy_shmid_from_user (&setbuf, buf, version)) {
619                         err = -EFAULT;
620                         goto out;
621                 }
622                 if ((err = audit_ipc_perms(0, setbuf.uid, setbuf.gid, setbuf.mode)))
623                         return err;
624                 down(&shm_ids.sem);
625                 shp = shm_lock(shmid);
626                 err=-EINVAL;
627                 if(shp==NULL)
628                         goto out_up;
629                 err = shm_checkid(shp,shmid);
630                 if(err)
631                         goto out_unlock_up;
632                 err=-EPERM;
633                 if (current->euid != shp->shm_perm.uid &&
634                     current->euid != shp->shm_perm.cuid && 
635                     !capable(CAP_SYS_ADMIN)) {
636                         goto out_unlock_up;
637                 }
638
639                 err = security_shm_shmctl(shp, cmd);
640                 if (err)
641                         goto out_unlock_up;
642                 
643                 shp->shm_perm.uid = setbuf.uid;
644                 shp->shm_perm.gid = setbuf.gid;
645                 shp->shm_perm.mode = (shp->shm_perm.mode & ~S_IRWXUGO)
646                         | (setbuf.mode & S_IRWXUGO);
647                 shp->shm_ctim = get_seconds();
648                 break;
649         }
650
651         default:
652                 err = -EINVAL;
653                 goto out;
654         }
655
656         err = 0;
657 out_unlock_up:
658         shm_unlock(shp);
659 out_up:
660         up(&shm_ids.sem);
661         goto out;
662 out_unlock:
663         shm_unlock(shp);
664 out:
665         return err;
666 }
667
668 /*
669  * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
670  *
671  * NOTE! Despite the name, this is NOT a direct system call entrypoint. The
672  * "raddr" thing points to kernel space, and there has to be a wrapper around
673  * this.
674  */
675 long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr)
676 {
677         struct shmid_kernel *shp;
678         unsigned long addr;
679         unsigned long size;
680         struct file * file;
681         int    err;
682         unsigned long flags;
683         unsigned long prot;
684         unsigned long o_flags;
685         int acc_mode;
686         void *user_addr;
687
688         if (shmid < 0) {
689                 err = -EINVAL;
690                 goto out;
691         } else if ((addr = (ulong)shmaddr)) {
692                 if (addr & (SHMLBA-1)) {
693                         if (shmflg & SHM_RND)
694                                 addr &= ~(SHMLBA-1);       /* round down */
695                         else
696 #ifndef __ARCH_FORCE_SHMLBA
697                                 if (addr & ~PAGE_MASK)
698 #endif
699                                         return -EINVAL;
700                 }
701                 flags = MAP_SHARED | MAP_FIXED;
702         } else {
703                 if ((shmflg & SHM_REMAP))
704                         return -EINVAL;
705
706                 flags = MAP_SHARED;
707         }
708
709         if (shmflg & SHM_RDONLY) {
710                 prot = PROT_READ;
711                 o_flags = O_RDONLY;
712                 acc_mode = S_IRUGO;
713         } else {
714                 prot = PROT_READ | PROT_WRITE;
715                 o_flags = O_RDWR;
716                 acc_mode = S_IRUGO | S_IWUGO;
717         }
718         if (shmflg & SHM_EXEC) {
719                 prot |= PROT_EXEC;
720                 acc_mode |= S_IXUGO;
721         }
722
723         /*
724          * We cannot rely on the fs check since SYSV IPC does have an
725          * additional creator id...
726          */
727         shp = shm_lock(shmid);
728         if(shp == NULL) {
729                 err = -EINVAL;
730                 goto out;
731         }
732         err = shm_checkid(shp,shmid);
733         if (err) {
734                 shm_unlock(shp);
735                 goto out;
736         }
737         if (ipcperms(&shp->shm_perm, acc_mode)) {
738                 shm_unlock(shp);
739                 err = -EACCES;
740                 goto out;
741         }
742
743         err = security_shm_shmat(shp, shmaddr, shmflg);
744         if (err) {
745                 shm_unlock(shp);
746                 return err;
747         }
748                 
749         file = shp->shm_file;
750         size = i_size_read(file->f_dentry->d_inode);
751         shp->shm_nattch++;
752         shm_unlock(shp);
753
754         down_write(&current->mm->mmap_sem);
755         if (addr && !(shmflg & SHM_REMAP)) {
756                 user_addr = ERR_PTR(-EINVAL);
757                 if (find_vma_intersection(current->mm, addr, addr + size))
758                         goto invalid;
759                 /*
760                  * If shm segment goes below stack, make sure there is some
761                  * space left for the stack to grow (at least 4 pages).
762                  */
763                 if (addr < current->mm->start_stack &&
764                     addr > current->mm->start_stack - size - PAGE_SIZE * 5)
765                         goto invalid;
766         }
767                 
768         user_addr = (void*) do_mmap (file, addr, size, prot, flags, 0);
769
770 invalid:
771         up_write(&current->mm->mmap_sem);
772
773         down (&shm_ids.sem);
774         if(!(shp = shm_lock(shmid)))
775                 BUG();
776         shp->shm_nattch--;
777         if(shp->shm_nattch == 0 &&
778            shp->shm_perm.mode & SHM_DEST)
779                 shm_destroy (shp);
780         else
781                 shm_unlock(shp);
782         up (&shm_ids.sem);
783
784         *raddr = (unsigned long) user_addr;
785         err = 0;
786         if (IS_ERR(user_addr))
787                 err = PTR_ERR(user_addr);
788 out:
789         return err;
790 }
791
792 asmlinkage long sys_shmat(int shmid, char __user *shmaddr, int shmflg)
793 {
794         unsigned long ret;
795         long err;
796
797         err = do_shmat(shmid, shmaddr, shmflg, &ret);
798         if (err)
799                 return err;
800         force_successful_syscall_return();
801         return (long)ret;
802 }
803
804 /*
805  * detach and kill segment if marked destroyed.
806  * The work is done in shm_close.
807  */
808 asmlinkage long sys_shmdt(char __user *shmaddr)
809 {
810         struct mm_struct *mm = current->mm;
811         struct vm_area_struct *vma, *next;
812         unsigned long addr = (unsigned long)shmaddr;
813         loff_t size = 0;
814         int retval = -EINVAL;
815
816         down_write(&mm->mmap_sem);
817
818         /*
819          * This function tries to be smart and unmap shm segments that
820          * were modified by partial mlock or munmap calls:
821          * - It first determines the size of the shm segment that should be
822          *   unmapped: It searches for a vma that is backed by shm and that
823          *   started at address shmaddr. It records it's size and then unmaps
824          *   it.
825          * - Then it unmaps all shm vmas that started at shmaddr and that
826          *   are within the initially determined size.
827          * Errors from do_munmap are ignored: the function only fails if
828          * it's called with invalid parameters or if it's called to unmap
829          * a part of a vma. Both calls in this function are for full vmas,
830          * the parameters are directly copied from the vma itself and always
831          * valid - therefore do_munmap cannot fail. (famous last words?)
832          */
833         /*
834          * If it had been mremap()'d, the starting address would not
835          * match the usual checks anyway. So assume all vma's are
836          * above the starting address given.
837          */
838         vma = find_vma(mm, addr);
839
840         while (vma) {
841                 next = vma->vm_next;
842
843                 /*
844                  * Check if the starting address would match, i.e. it's
845                  * a fragment created by mprotect() and/or munmap(), or it
846                  * otherwise it starts at this address with no hassles.
847                  */
848                 if ((vma->vm_ops == &shm_vm_ops || is_vm_hugetlb_page(vma)) &&
849                         (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) {
850
851
852                         size = vma->vm_file->f_dentry->d_inode->i_size;
853                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
854                         /*
855                          * We discovered the size of the shm segment, so
856                          * break out of here and fall through to the next
857                          * loop that uses the size information to stop
858                          * searching for matching vma's.
859                          */
860                         retval = 0;
861                         vma = next;
862                         break;
863                 }
864                 vma = next;
865         }
866
867         /*
868          * We need look no further than the maximum address a fragment
869          * could possibly have landed at. Also cast things to loff_t to
870          * prevent overflows and make comparisions vs. equal-width types.
871          */
872         while (vma && (loff_t)(vma->vm_end - addr) <= size) {
873                 next = vma->vm_next;
874
875                 /* finding a matching vma now does not alter retval */
876                 if ((vma->vm_ops == &shm_vm_ops || is_vm_hugetlb_page(vma)) &&
877                         (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff)
878
879                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
880                 vma = next;
881         }
882
883         up_write(&mm->mmap_sem);
884         return retval;
885 }
886
887 #ifdef CONFIG_PROC_FS
888 static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
889 {
890         struct shmid_kernel *shp = it;
891         char *format;
892
893 #define SMALL_STRING "%10d %10d  %4o %10u %5u %5u  %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
894 #define BIG_STRING   "%10d %10d  %4o %21u %5u %5u  %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
895
896         if (sizeof(size_t) <= sizeof(int))
897                 format = SMALL_STRING;
898         else
899                 format = BIG_STRING;
900         return seq_printf(s, format,
901                           shp->shm_perm.key,
902                           shp->id,
903                           shp->shm_perm.mode,
904                           shp->shm_segsz,
905                           shp->shm_cprid,
906                           shp->shm_lprid,
907                           is_file_hugepages(shp->shm_file) ? (file_count(shp->shm_file) - 1) : shp->shm_nattch,
908                           shp->shm_perm.uid,
909                           shp->shm_perm.gid,
910                           shp->shm_perm.cuid,
911                           shp->shm_perm.cgid,
912                           shp->shm_atim,
913                           shp->shm_dtim,
914                           shp->shm_ctim);
915 }
916 #endif