[PATCH] pcmcia: remove references to pcmcia/version.h
[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/proc_fs.h>
27 #include <linux/shmem_fs.h>
28 #include <linux/security.h>
29 #include <linux/syscalls.h>
30 #include <linux/audit.h>
31 #include <linux/ptrace.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_read_proc(char *buffer, char **start, off_t offset, int length, int *eof, void *data);
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 #ifdef CONFIG_PROC_FS
67         create_proc_read_entry("sysvipc/shm", 0, NULL, sysvipc_shm_read_proc, NULL);
68 #endif
69 }
70
71 static inline int shm_checkid(struct shmid_kernel *s, int id)
72 {
73         if (ipc_checkid(&shm_ids,&s->shm_perm,id))
74                 return -EIDRM;
75         return 0;
76 }
77
78 static inline struct shmid_kernel *shm_rmid(int id)
79 {
80         return (struct shmid_kernel *)ipc_rmid(&shm_ids,id);
81 }
82
83 static inline int shm_addid(struct shmid_kernel *shp)
84 {
85         return ipc_addid(&shm_ids, &shp->shm_perm, shm_ctlmni);
86 }
87
88
89
90 static inline void shm_inc (int id) {
91         struct shmid_kernel *shp;
92
93         if(!(shp = shm_lock(id)))
94                 BUG();
95         shp->shm_atim = get_seconds();
96         shp->shm_lprid = current->tgid;
97         shp->shm_nattch++;
98         shm_unlock(shp);
99 }
100
101 /* This is called by fork, once for every shm attach. */
102 static void shm_open (struct vm_area_struct *shmd)
103 {
104         shm_inc (shmd->vm_file->f_dentry->d_inode->i_ino);
105 }
106
107 /*
108  * shm_destroy - free the struct shmid_kernel
109  *
110  * @shp: struct to free
111  *
112  * It has to be called with shp and shm_ids.sem locked,
113  * but returns with shp unlocked and freed.
114  */
115 static void shm_destroy (struct shmid_kernel *shp)
116 {
117         shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT;
118         shm_rmid (shp->id);
119         shm_unlock(shp);
120         if (!is_file_hugepages(shp->shm_file))
121                 shmem_lock(shp->shm_file, 0, shp->mlock_user);
122         else
123                 user_shm_unlock(shp->shm_file->f_dentry->d_inode->i_size,
124                                                 shp->mlock_user);
125         fput (shp->shm_file);
126         security_shm_free(shp);
127         ipc_rcu_putref(shp);
128 }
129
130 /*
131  * remove the attach descriptor shmd.
132  * free memory for segment if it is marked destroyed.
133  * The descriptor has already been removed from the current->mm->mmap list
134  * and will later be kfree()d.
135  */
136 static void shm_close (struct vm_area_struct *shmd)
137 {
138         struct file * file = shmd->vm_file;
139         int id = file->f_dentry->d_inode->i_ino;
140         struct shmid_kernel *shp;
141
142         down (&shm_ids.sem);
143         /* remove from the list of attaches of the shm segment */
144         if(!(shp = shm_lock(id)))
145                 BUG();
146         shp->shm_lprid = current->tgid;
147         shp->shm_dtim = get_seconds();
148         shp->shm_nattch--;
149         if(shp->shm_nattch == 0 &&
150            shp->shm_flags & SHM_DEST)
151                 shm_destroy (shp);
152         else
153                 shm_unlock(shp);
154         up (&shm_ids.sem);
155 }
156
157 static int shm_mmap(struct file * file, struct vm_area_struct * vma)
158 {
159         file_accessed(file);
160         vma->vm_ops = &shm_vm_ops;
161         shm_inc(file->f_dentry->d_inode->i_ino);
162         return 0;
163 }
164
165 static struct file_operations shm_file_operations = {
166         .mmap   = shm_mmap
167 };
168
169 static struct vm_operations_struct shm_vm_ops = {
170         .open   = shm_open,     /* callback for a new vm-area open */
171         .close  = shm_close,    /* callback for when the vm-area is released */
172         .nopage = shmem_nopage,
173 #ifdef CONFIG_NUMA
174         .set_policy = shmem_set_policy,
175         .get_policy = shmem_get_policy,
176 #endif
177 };
178
179 static int newseg (key_t key, int shmflg, size_t size)
180 {
181         int error;
182         struct shmid_kernel *shp;
183         int numpages = (size + PAGE_SIZE -1) >> PAGE_SHIFT;
184         struct file * file;
185         char name[13];
186         int id;
187
188         if (size < SHMMIN || size > shm_ctlmax)
189                 return -EINVAL;
190
191         if (shm_tot + numpages >= shm_ctlall)
192                 return -ENOSPC;
193
194         shp = ipc_rcu_alloc(sizeof(*shp));
195         if (!shp)
196                 return -ENOMEM;
197
198         shp->shm_perm.key = key;
199         shp->shm_flags = (shmflg & S_IRWXUGO);
200         shp->mlock_user = NULL;
201
202         shp->shm_perm.security = NULL;
203         error = security_shm_alloc(shp);
204         if (error) {
205                 ipc_rcu_putref(shp);
206                 return error;
207         }
208
209         if (shmflg & SHM_HUGETLB) {
210                 /* hugetlb_zero_setup takes care of mlock user accounting */
211                 file = hugetlb_zero_setup(size);
212                 shp->mlock_user = current->user;
213         } else {
214                 sprintf (name, "SYSV%08x", key);
215                 file = shmem_file_setup(name, size, VM_ACCOUNT);
216         }
217         error = PTR_ERR(file);
218         if (IS_ERR(file))
219                 goto no_file;
220
221         error = -ENOSPC;
222         id = shm_addid(shp);
223         if(id == -1) 
224                 goto no_id;
225
226         shp->shm_cprid = current->tgid;
227         shp->shm_lprid = 0;
228         shp->shm_atim = shp->shm_dtim = 0;
229         shp->shm_ctim = get_seconds();
230         shp->shm_segsz = size;
231         shp->shm_nattch = 0;
232         shp->id = shm_buildid(id,shp->shm_perm.seq);
233         shp->shm_file = file;
234         file->f_dentry->d_inode->i_ino = shp->id;
235         if (shmflg & SHM_HUGETLB)
236                 set_file_hugepages(file);
237         else
238                 file->f_op = &shm_file_operations;
239         shm_tot += numpages;
240         shm_unlock(shp);
241         return shp->id;
242
243 no_id:
244         fput(file);
245 no_file:
246         security_shm_free(shp);
247         ipc_rcu_putref(shp);
248         return error;
249 }
250
251 asmlinkage long sys_shmget (key_t key, size_t size, int shmflg)
252 {
253         struct shmid_kernel *shp;
254         int err, id = 0;
255
256         down(&shm_ids.sem);
257         if (key == IPC_PRIVATE) {
258                 err = newseg(key, shmflg, size);
259         } else if ((id = ipc_findkey(&shm_ids, key)) == -1) {
260                 if (!(shmflg & IPC_CREAT))
261                         err = -ENOENT;
262                 else
263                         err = newseg(key, shmflg, size);
264         } else if ((shmflg & IPC_CREAT) && (shmflg & IPC_EXCL)) {
265                 err = -EEXIST;
266         } else {
267                 shp = shm_lock(id);
268                 if(shp==NULL)
269                         BUG();
270                 if (shp->shm_segsz < size)
271                         err = -EINVAL;
272                 else if (ipcperms(&shp->shm_perm, shmflg))
273                         err = -EACCES;
274                 else {
275                         int shmid = shm_buildid(id, shp->shm_perm.seq);
276                         err = security_shm_associate(shp, shmflg);
277                         if (!err)
278                                 err = shmid;
279                 }
280                 shm_unlock(shp);
281         }
282         up(&shm_ids.sem);
283
284         return err;
285 }
286
287 static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version)
288 {
289         switch(version) {
290         case IPC_64:
291                 return copy_to_user(buf, in, sizeof(*in));
292         case IPC_OLD:
293             {
294                 struct shmid_ds out;
295
296                 ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
297                 out.shm_segsz   = in->shm_segsz;
298                 out.shm_atime   = in->shm_atime;
299                 out.shm_dtime   = in->shm_dtime;
300                 out.shm_ctime   = in->shm_ctime;
301                 out.shm_cpid    = in->shm_cpid;
302                 out.shm_lpid    = in->shm_lpid;
303                 out.shm_nattch  = in->shm_nattch;
304
305                 return copy_to_user(buf, &out, sizeof(out));
306             }
307         default:
308                 return -EINVAL;
309         }
310 }
311
312 struct shm_setbuf {
313         uid_t   uid;
314         gid_t   gid;
315         mode_t  mode;
316 };      
317
318 static inline unsigned long copy_shmid_from_user(struct shm_setbuf *out, void __user *buf, int version)
319 {
320         switch(version) {
321         case IPC_64:
322             {
323                 struct shmid64_ds tbuf;
324
325                 if (copy_from_user(&tbuf, buf, sizeof(tbuf)))
326                         return -EFAULT;
327
328                 out->uid        = tbuf.shm_perm.uid;
329                 out->gid        = tbuf.shm_perm.gid;
330                 out->mode       = tbuf.shm_flags;
331
332                 return 0;
333             }
334         case IPC_OLD:
335             {
336                 struct shmid_ds tbuf_old;
337
338                 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
339                         return -EFAULT;
340
341                 out->uid        = tbuf_old.shm_perm.uid;
342                 out->gid        = tbuf_old.shm_perm.gid;
343                 out->mode       = tbuf_old.shm_flags;
344
345                 return 0;
346             }
347         default:
348                 return -EINVAL;
349         }
350 }
351
352 static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminfo64 *in, int version)
353 {
354         switch(version) {
355         case IPC_64:
356                 return copy_to_user(buf, in, sizeof(*in));
357         case IPC_OLD:
358             {
359                 struct shminfo out;
360
361                 if(in->shmmax > INT_MAX)
362                         out.shmmax = INT_MAX;
363                 else
364                         out.shmmax = (int)in->shmmax;
365
366                 out.shmmin      = in->shmmin;
367                 out.shmmni      = in->shmmni;
368                 out.shmseg      = in->shmseg;
369                 out.shmall      = in->shmall; 
370
371                 return copy_to_user(buf, &out, sizeof(out));
372             }
373         default:
374                 return -EINVAL;
375         }
376 }
377
378 static void shm_get_stat(unsigned long *rss, unsigned long *swp) 
379 {
380         int i;
381
382         *rss = 0;
383         *swp = 0;
384
385         for (i = 0; i <= shm_ids.max_id; i++) {
386                 struct shmid_kernel *shp;
387                 struct inode *inode;
388
389                 shp = shm_get(i);
390                 if(!shp)
391                         continue;
392
393                 inode = shp->shm_file->f_dentry->d_inode;
394
395                 if (is_file_hugepages(shp->shm_file)) {
396                         struct address_space *mapping = inode->i_mapping;
397                         *rss += (HPAGE_SIZE/PAGE_SIZE)*mapping->nrpages;
398                 } else {
399                         struct shmem_inode_info *info = SHMEM_I(inode);
400                         spin_lock(&info->lock);
401                         *rss += inode->i_mapping->nrpages;
402                         *swp += info->swapped;
403                         spin_unlock(&info->lock);
404                 }
405         }
406 }
407
408 asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds __user *buf)
409 {
410         struct shm_setbuf setbuf;
411         struct shmid_kernel *shp;
412         int err, version;
413
414         if (cmd < 0 || shmid < 0) {
415                 err = -EINVAL;
416                 goto out;
417         }
418
419         version = ipc_parse_version(&cmd);
420
421         switch (cmd) { /* replace with proc interface ? */
422         case IPC_INFO:
423         {
424                 struct shminfo64 shminfo;
425
426                 err = security_shm_shmctl(NULL, cmd);
427                 if (err)
428                         return err;
429
430                 memset(&shminfo,0,sizeof(shminfo));
431                 shminfo.shmmni = shminfo.shmseg = shm_ctlmni;
432                 shminfo.shmmax = shm_ctlmax;
433                 shminfo.shmall = shm_ctlall;
434
435                 shminfo.shmmin = SHMMIN;
436                 if(copy_shminfo_to_user (buf, &shminfo, version))
437                         return -EFAULT;
438                 /* reading a integer is always atomic */
439                 err= shm_ids.max_id;
440                 if(err<0)
441                         err = 0;
442                 goto out;
443         }
444         case SHM_INFO:
445         {
446                 struct shm_info shm_info;
447
448                 err = security_shm_shmctl(NULL, cmd);
449                 if (err)
450                         return err;
451
452                 memset(&shm_info,0,sizeof(shm_info));
453                 down(&shm_ids.sem);
454                 shm_info.used_ids = shm_ids.in_use;
455                 shm_get_stat (&shm_info.shm_rss, &shm_info.shm_swp);
456                 shm_info.shm_tot = shm_tot;
457                 shm_info.swap_attempts = 0;
458                 shm_info.swap_successes = 0;
459                 err = shm_ids.max_id;
460                 up(&shm_ids.sem);
461                 if(copy_to_user (buf, &shm_info, sizeof(shm_info))) {
462                         err = -EFAULT;
463                         goto out;
464                 }
465
466                 err = err < 0 ? 0 : err;
467                 goto out;
468         }
469         case SHM_STAT:
470         case IPC_STAT:
471         {
472                 struct shmid64_ds tbuf;
473                 int result;
474                 memset(&tbuf, 0, sizeof(tbuf));
475                 shp = shm_lock(shmid);
476                 if(shp==NULL) {
477                         err = -EINVAL;
478                         goto out;
479                 } else if(cmd==SHM_STAT) {
480                         err = -EINVAL;
481                         if (shmid > shm_ids.max_id)
482                                 goto out_unlock;
483                         result = shm_buildid(shmid, shp->shm_perm.seq);
484                 } else {
485                         err = shm_checkid(shp,shmid);
486                         if(err)
487                                 goto out_unlock;
488                         result = 0;
489                 }
490                 err=-EACCES;
491                 if (ipcperms (&shp->shm_perm, S_IRUGO))
492                         goto out_unlock;
493                 err = security_shm_shmctl(shp, cmd);
494                 if (err)
495                         goto out_unlock;
496                 kernel_to_ipc64_perm(&shp->shm_perm, &tbuf.shm_perm);
497                 tbuf.shm_segsz  = shp->shm_segsz;
498                 tbuf.shm_atime  = shp->shm_atim;
499                 tbuf.shm_dtime  = shp->shm_dtim;
500                 tbuf.shm_ctime  = shp->shm_ctim;
501                 tbuf.shm_cpid   = shp->shm_cprid;
502                 tbuf.shm_lpid   = shp->shm_lprid;
503                 if (!is_file_hugepages(shp->shm_file))
504                         tbuf.shm_nattch = shp->shm_nattch;
505                 else
506                         tbuf.shm_nattch = file_count(shp->shm_file) - 1;
507                 shm_unlock(shp);
508                 if(copy_shmid_to_user (buf, &tbuf, version))
509                         err = -EFAULT;
510                 else
511                         err = result;
512                 goto out;
513         }
514         case SHM_LOCK:
515         case SHM_UNLOCK:
516         {
517                 shp = shm_lock(shmid);
518                 if(shp==NULL) {
519                         err = -EINVAL;
520                         goto out;
521                 }
522                 err = shm_checkid(shp,shmid);
523                 if(err)
524                         goto out_unlock;
525
526                 if (!capable(CAP_IPC_LOCK)) {
527                         err = -EPERM;
528                         if (current->euid != shp->shm_perm.uid &&
529                             current->euid != shp->shm_perm.cuid)
530                                 goto out_unlock;
531                         if (cmd == SHM_LOCK &&
532                             !current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur)
533                                 goto out_unlock;
534                 }
535
536                 err = security_shm_shmctl(shp, cmd);
537                 if (err)
538                         goto out_unlock;
539                 
540                 if(cmd==SHM_LOCK) {
541                         struct user_struct * user = current->user;
542                         if (!is_file_hugepages(shp->shm_file)) {
543                                 err = shmem_lock(shp->shm_file, 1, user);
544                                 if (!err) {
545                                         shp->shm_flags |= SHM_LOCKED;
546                                         shp->mlock_user = user;
547                                 }
548                         }
549                 } else if (!is_file_hugepages(shp->shm_file)) {
550                         shmem_lock(shp->shm_file, 0, shp->mlock_user);
551                         shp->shm_flags &= ~SHM_LOCKED;
552                         shp->mlock_user = NULL;
553                 }
554                 shm_unlock(shp);
555                 goto out;
556         }
557         case IPC_RMID:
558         {
559                 /*
560                  *      We cannot simply remove the file. The SVID states
561                  *      that the block remains until the last person
562                  *      detaches from it, then is deleted. A shmat() on
563                  *      an RMID segment is legal in older Linux and if 
564                  *      we change it apps break...
565                  *
566                  *      Instead we set a destroyed flag, and then blow
567                  *      the name away when the usage hits zero.
568                  */
569                 down(&shm_ids.sem);
570                 shp = shm_lock(shmid);
571                 err = -EINVAL;
572                 if (shp == NULL) 
573                         goto out_up;
574                 err = shm_checkid(shp, shmid);
575                 if(err)
576                         goto out_unlock_up;
577
578                 if (current->euid != shp->shm_perm.uid &&
579                     current->euid != shp->shm_perm.cuid && 
580                     !capable(CAP_SYS_ADMIN)) {
581                         err=-EPERM;
582                         goto out_unlock_up;
583                 }
584
585                 err = security_shm_shmctl(shp, cmd);
586                 if (err)
587                         goto out_unlock_up;
588
589                 if (shp->shm_nattch){
590                         shp->shm_flags |= SHM_DEST;
591                         /* Do not find it any more */
592                         shp->shm_perm.key = IPC_PRIVATE;
593                         shm_unlock(shp);
594                 } else
595                         shm_destroy (shp);
596                 up(&shm_ids.sem);
597                 goto out;
598         }
599
600         case IPC_SET:
601         {
602                 if (copy_shmid_from_user (&setbuf, buf, version)) {
603                         err = -EFAULT;
604                         goto out;
605                 }
606                 if ((err = audit_ipc_perms(0, setbuf.uid, setbuf.gid, setbuf.mode)))
607                         return err;
608                 down(&shm_ids.sem);
609                 shp = shm_lock(shmid);
610                 err=-EINVAL;
611                 if(shp==NULL)
612                         goto out_up;
613                 err = shm_checkid(shp,shmid);
614                 if(err)
615                         goto out_unlock_up;
616                 err=-EPERM;
617                 if (current->euid != shp->shm_perm.uid &&
618                     current->euid != shp->shm_perm.cuid && 
619                     !capable(CAP_SYS_ADMIN)) {
620                         goto out_unlock_up;
621                 }
622
623                 err = security_shm_shmctl(shp, cmd);
624                 if (err)
625                         goto out_unlock_up;
626                 
627                 shp->shm_perm.uid = setbuf.uid;
628                 shp->shm_perm.gid = setbuf.gid;
629                 shp->shm_flags = (shp->shm_flags & ~S_IRWXUGO)
630                         | (setbuf.mode & S_IRWXUGO);
631                 shp->shm_ctim = get_seconds();
632                 break;
633         }
634
635         default:
636                 err = -EINVAL;
637                 goto out;
638         }
639
640         err = 0;
641 out_unlock_up:
642         shm_unlock(shp);
643 out_up:
644         up(&shm_ids.sem);
645         goto out;
646 out_unlock:
647         shm_unlock(shp);
648 out:
649         return err;
650 }
651
652 /*
653  * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
654  *
655  * NOTE! Despite the name, this is NOT a direct system call entrypoint. The
656  * "raddr" thing points to kernel space, and there has to be a wrapper around
657  * this.
658  */
659 long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr)
660 {
661         struct shmid_kernel *shp;
662         unsigned long addr;
663         unsigned long size;
664         struct file * file;
665         int    err;
666         unsigned long flags;
667         unsigned long prot;
668         unsigned long o_flags;
669         int acc_mode;
670         void *user_addr;
671
672         if (shmid < 0) {
673                 err = -EINVAL;
674                 goto out;
675         } else if ((addr = (ulong)shmaddr)) {
676                 if (addr & (SHMLBA-1)) {
677                         if (shmflg & SHM_RND)
678                                 addr &= ~(SHMLBA-1);       /* round down */
679                         else
680 #ifndef __ARCH_FORCE_SHMLBA
681                                 if (addr & ~PAGE_MASK)
682 #endif
683                                         return -EINVAL;
684                 }
685                 flags = MAP_SHARED | MAP_FIXED;
686         } else {
687                 if ((shmflg & SHM_REMAP))
688                         return -EINVAL;
689
690                 flags = MAP_SHARED;
691         }
692
693         if (shmflg & SHM_RDONLY) {
694                 prot = PROT_READ;
695                 o_flags = O_RDONLY;
696                 acc_mode = S_IRUGO;
697         } else {
698                 prot = PROT_READ | PROT_WRITE;
699                 o_flags = O_RDWR;
700                 acc_mode = S_IRUGO | S_IWUGO;
701         }
702         if (shmflg & SHM_EXEC) {
703                 prot |= PROT_EXEC;
704                 acc_mode |= S_IXUGO;
705         }
706
707         /*
708          * We cannot rely on the fs check since SYSV IPC does have an
709          * additional creator id...
710          */
711         shp = shm_lock(shmid);
712         if(shp == NULL) {
713                 err = -EINVAL;
714                 goto out;
715         }
716         err = shm_checkid(shp,shmid);
717         if (err) {
718                 shm_unlock(shp);
719                 goto out;
720         }
721         if (ipcperms(&shp->shm_perm, acc_mode)) {
722                 shm_unlock(shp);
723                 err = -EACCES;
724                 goto out;
725         }
726
727         err = security_shm_shmat(shp, shmaddr, shmflg);
728         if (err) {
729                 shm_unlock(shp);
730                 return err;
731         }
732                 
733         file = shp->shm_file;
734         size = i_size_read(file->f_dentry->d_inode);
735         shp->shm_nattch++;
736         shm_unlock(shp);
737
738         down_write(&current->mm->mmap_sem);
739         if (addr && !(shmflg & SHM_REMAP)) {
740                 user_addr = ERR_PTR(-EINVAL);
741                 if (find_vma_intersection(current->mm, addr, addr + size))
742                         goto invalid;
743                 /*
744                  * If shm segment goes below stack, make sure there is some
745                  * space left for the stack to grow (at least 4 pages).
746                  */
747                 if (addr < current->mm->start_stack &&
748                     addr > current->mm->start_stack - size - PAGE_SIZE * 5)
749                         goto invalid;
750         }
751                 
752         user_addr = (void*) do_mmap (file, addr, size, prot, flags, 0);
753
754 invalid:
755         up_write(&current->mm->mmap_sem);
756
757         down (&shm_ids.sem);
758         if(!(shp = shm_lock(shmid)))
759                 BUG();
760         shp->shm_nattch--;
761         if(shp->shm_nattch == 0 &&
762            shp->shm_flags & SHM_DEST)
763                 shm_destroy (shp);
764         else
765                 shm_unlock(shp);
766         up (&shm_ids.sem);
767
768         *raddr = (unsigned long) user_addr;
769         err = 0;
770         if (IS_ERR(user_addr))
771                 err = PTR_ERR(user_addr);
772 out:
773         return err;
774 }
775
776 asmlinkage long sys_shmat(int shmid, char __user *shmaddr, int shmflg)
777 {
778         unsigned long ret;
779         long err;
780
781         err = do_shmat(shmid, shmaddr, shmflg, &ret);
782         if (err)
783                 return err;
784         force_successful_syscall_return();
785         return (long)ret;
786 }
787
788 /*
789  * detach and kill segment if marked destroyed.
790  * The work is done in shm_close.
791  */
792 asmlinkage long sys_shmdt(char __user *shmaddr)
793 {
794         struct mm_struct *mm = current->mm;
795         struct vm_area_struct *vma, *next;
796         unsigned long addr = (unsigned long)shmaddr;
797         loff_t size = 0;
798         int retval = -EINVAL;
799
800         down_write(&mm->mmap_sem);
801
802         /*
803          * This function tries to be smart and unmap shm segments that
804          * were modified by partial mlock or munmap calls:
805          * - It first determines the size of the shm segment that should be
806          *   unmapped: It searches for a vma that is backed by shm and that
807          *   started at address shmaddr. It records it's size and then unmaps
808          *   it.
809          * - Then it unmaps all shm vmas that started at shmaddr and that
810          *   are within the initially determined size.
811          * Errors from do_munmap are ignored: the function only fails if
812          * it's called with invalid parameters or if it's called to unmap
813          * a part of a vma. Both calls in this function are for full vmas,
814          * the parameters are directly copied from the vma itself and always
815          * valid - therefore do_munmap cannot fail. (famous last words?)
816          */
817         /*
818          * If it had been mremap()'d, the starting address would not
819          * match the usual checks anyway. So assume all vma's are
820          * above the starting address given.
821          */
822         vma = find_vma(mm, addr);
823
824         while (vma) {
825                 next = vma->vm_next;
826
827                 /*
828                  * Check if the starting address would match, i.e. it's
829                  * a fragment created by mprotect() and/or munmap(), or it
830                  * otherwise it starts at this address with no hassles.
831                  */
832                 if ((vma->vm_ops == &shm_vm_ops || is_vm_hugetlb_page(vma)) &&
833                         (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) {
834
835
836                         size = vma->vm_file->f_dentry->d_inode->i_size;
837                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
838                         /*
839                          * We discovered the size of the shm segment, so
840                          * break out of here and fall through to the next
841                          * loop that uses the size information to stop
842                          * searching for matching vma's.
843                          */
844                         retval = 0;
845                         vma = next;
846                         break;
847                 }
848                 vma = next;
849         }
850
851         /*
852          * We need look no further than the maximum address a fragment
853          * could possibly have landed at. Also cast things to loff_t to
854          * prevent overflows and make comparisions vs. equal-width types.
855          */
856         while (vma && (loff_t)(vma->vm_end - addr) <= size) {
857                 next = vma->vm_next;
858
859                 /* finding a matching vma now does not alter retval */
860                 if ((vma->vm_ops == &shm_vm_ops || is_vm_hugetlb_page(vma)) &&
861                         (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff)
862
863                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
864                 vma = next;
865         }
866
867         up_write(&mm->mmap_sem);
868         return retval;
869 }
870
871 #ifdef CONFIG_PROC_FS
872 static int sysvipc_shm_read_proc(char *buffer, char **start, off_t offset, int length, int *eof, void *data)
873 {
874         off_t pos = 0;
875         off_t begin = 0;
876         int i, len = 0;
877
878         down(&shm_ids.sem);
879         len += sprintf(buffer, "       key      shmid perms       size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime\n");
880
881         for(i = 0; i <= shm_ids.max_id; i++) {
882                 struct shmid_kernel* shp;
883
884                 shp = shm_lock(i);
885                 if(shp!=NULL) {
886 #define SMALL_STRING "%10d %10d  %4o %10u %5u %5u  %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
887 #define BIG_STRING   "%10d %10d  %4o %21u %5u %5u  %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
888                         char *format;
889
890                         if (sizeof(size_t) <= sizeof(int))
891                                 format = SMALL_STRING;
892                         else
893                                 format = BIG_STRING;
894                         len += sprintf(buffer + len, format,
895                                 shp->shm_perm.key,
896                                 shm_buildid(i, shp->shm_perm.seq),
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                         shm_unlock(shp);
910
911                         pos += len;
912                         if(pos < offset) {
913                                 len = 0;
914                                 begin = pos;
915                         }
916                         if(pos > offset + length)
917                                 goto done;
918                 }
919         }
920         *eof = 1;
921 done:
922         up(&shm_ids.sem);
923         *start = buffer + (offset - begin);
924         len -= (offset - begin);
925         if(len > length)
926                 len = length;
927         if(len < 0)
928                 len = 0;
929         return len;
930 }
931 #endif