[PATCH] Capture selinux subject/object context information.
[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/capability.h>
31 #include <linux/ptrace.h>
32 #include <linux/seq_file.h>
33
34 #include <asm/uaccess.h>
35
36 #include "util.h"
37
38 static struct file_operations shm_file_operations;
39 static struct vm_operations_struct shm_vm_ops;
40
41 static struct ipc_ids shm_ids;
42
43 #define shm_lock(id)    ((struct shmid_kernel*)ipc_lock(&shm_ids,id))
44 #define shm_unlock(shp) ipc_unlock(&(shp)->shm_perm)
45 #define shm_get(id)     ((struct shmid_kernel*)ipc_get(&shm_ids,id))
46 #define shm_buildid(id, seq) \
47         ipc_buildid(&shm_ids, id, seq)
48
49 static int newseg (key_t key, int shmflg, size_t size);
50 static void shm_open (struct vm_area_struct *shmd);
51 static void shm_close (struct vm_area_struct *shmd);
52 #ifdef CONFIG_PROC_FS
53 static int sysvipc_shm_proc_show(struct seq_file *s, void *it);
54 #endif
55
56 size_t  shm_ctlmax = SHMMAX;
57 size_t  shm_ctlall = SHMALL;
58 int     shm_ctlmni = SHMMNI;
59
60 static int shm_tot; /* total number of shared memory pages */
61
62 void __init shm_init (void)
63 {
64         ipc_init_ids(&shm_ids, 1);
65         ipc_init_proc_interface("sysvipc/shm",
66                                 "       key      shmid perms       size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime\n",
67                                 &shm_ids,
68                                 sysvipc_shm_proc_show);
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_perm.mode & 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         int ret;
160
161         ret = shmem_mmap(file, vma);
162         if (ret == 0) {
163                 vma->vm_ops = &shm_vm_ops;
164                 shm_inc(file->f_dentry->d_inode->i_ino);
165         }
166
167         return ret;
168 }
169
170 static struct file_operations shm_file_operations = {
171         .mmap   = shm_mmap,
172 #ifndef CONFIG_MMU
173         .get_unmapped_area = shmem_get_unmapped_area,
174 #endif
175 };
176
177 static struct vm_operations_struct shm_vm_ops = {
178         .open   = shm_open,     /* callback for a new vm-area open */
179         .close  = shm_close,    /* callback for when the vm-area is released */
180         .nopage = shmem_nopage,
181 #if defined(CONFIG_NUMA) && defined(CONFIG_SHMEM)
182         .set_policy = shmem_set_policy,
183         .get_policy = shmem_get_policy,
184 #endif
185 };
186
187 static int newseg (key_t key, int shmflg, size_t size)
188 {
189         int error;
190         struct shmid_kernel *shp;
191         int numpages = (size + PAGE_SIZE -1) >> PAGE_SHIFT;
192         struct file * file;
193         char name[13];
194         int id;
195
196         if (size < SHMMIN || size > shm_ctlmax)
197                 return -EINVAL;
198
199         if (shm_tot + numpages >= shm_ctlall)
200                 return -ENOSPC;
201
202         shp = ipc_rcu_alloc(sizeof(*shp));
203         if (!shp)
204                 return -ENOMEM;
205
206         shp->shm_perm.key = key;
207         shp->shm_perm.mode = (shmflg & S_IRWXUGO);
208         shp->mlock_user = NULL;
209
210         shp->shm_perm.security = NULL;
211         error = security_shm_alloc(shp);
212         if (error) {
213                 ipc_rcu_putref(shp);
214                 return error;
215         }
216
217         if (shmflg & SHM_HUGETLB) {
218                 /* hugetlb_zero_setup takes care of mlock user accounting */
219                 file = hugetlb_zero_setup(size);
220                 shp->mlock_user = current->user;
221         } else {
222                 int acctflag = VM_ACCOUNT;
223                 /*
224                  * Do not allow no accounting for OVERCOMMIT_NEVER, even
225                  * if it's asked for.
226                  */
227                 if  ((shmflg & SHM_NORESERVE) &&
228                                 sysctl_overcommit_memory != OVERCOMMIT_NEVER)
229                         acctflag = 0;
230                 sprintf (name, "SYSV%08x", key);
231                 file = shmem_file_setup(name, size, acctflag);
232         }
233         error = PTR_ERR(file);
234         if (IS_ERR(file))
235                 goto no_file;
236
237         error = -ENOSPC;
238         id = shm_addid(shp);
239         if(id == -1) 
240                 goto no_id;
241
242         shp->shm_cprid = current->tgid;
243         shp->shm_lprid = 0;
244         shp->shm_atim = shp->shm_dtim = 0;
245         shp->shm_ctim = get_seconds();
246         shp->shm_segsz = size;
247         shp->shm_nattch = 0;
248         shp->id = shm_buildid(id,shp->shm_perm.seq);
249         shp->shm_file = file;
250         file->f_dentry->d_inode->i_ino = shp->id;
251
252         /* Hugetlb ops would have already been assigned. */
253         if (!(shmflg & SHM_HUGETLB))
254                 file->f_op = &shm_file_operations;
255
256         shm_tot += numpages;
257         shm_unlock(shp);
258         return shp->id;
259
260 no_id:
261         fput(file);
262 no_file:
263         security_shm_free(shp);
264         ipc_rcu_putref(shp);
265         return error;
266 }
267
268 asmlinkage long sys_shmget (key_t key, size_t size, int shmflg)
269 {
270         struct shmid_kernel *shp;
271         int err, id = 0;
272
273         down(&shm_ids.sem);
274         if (key == IPC_PRIVATE) {
275                 err = newseg(key, shmflg, size);
276         } else if ((id = ipc_findkey(&shm_ids, key)) == -1) {
277                 if (!(shmflg & IPC_CREAT))
278                         err = -ENOENT;
279                 else
280                         err = newseg(key, shmflg, size);
281         } else if ((shmflg & IPC_CREAT) && (shmflg & IPC_EXCL)) {
282                 err = -EEXIST;
283         } else {
284                 shp = shm_lock(id);
285                 if(shp==NULL)
286                         BUG();
287                 if (shp->shm_segsz < size)
288                         err = -EINVAL;
289                 else if (ipcperms(&shp->shm_perm, shmflg))
290                         err = -EACCES;
291                 else {
292                         int shmid = shm_buildid(id, shp->shm_perm.seq);
293                         err = security_shm_associate(shp, shmflg);
294                         if (!err)
295                                 err = shmid;
296                 }
297                 shm_unlock(shp);
298         }
299         up(&shm_ids.sem);
300
301         return err;
302 }
303
304 static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version)
305 {
306         switch(version) {
307         case IPC_64:
308                 return copy_to_user(buf, in, sizeof(*in));
309         case IPC_OLD:
310             {
311                 struct shmid_ds out;
312
313                 ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
314                 out.shm_segsz   = in->shm_segsz;
315                 out.shm_atime   = in->shm_atime;
316                 out.shm_dtime   = in->shm_dtime;
317                 out.shm_ctime   = in->shm_ctime;
318                 out.shm_cpid    = in->shm_cpid;
319                 out.shm_lpid    = in->shm_lpid;
320                 out.shm_nattch  = in->shm_nattch;
321
322                 return copy_to_user(buf, &out, sizeof(out));
323             }
324         default:
325                 return -EINVAL;
326         }
327 }
328
329 struct shm_setbuf {
330         uid_t   uid;
331         gid_t   gid;
332         mode_t  mode;
333 };      
334
335 static inline unsigned long copy_shmid_from_user(struct shm_setbuf *out, void __user *buf, int version)
336 {
337         switch(version) {
338         case IPC_64:
339             {
340                 struct shmid64_ds tbuf;
341
342                 if (copy_from_user(&tbuf, buf, sizeof(tbuf)))
343                         return -EFAULT;
344
345                 out->uid        = tbuf.shm_perm.uid;
346                 out->gid        = tbuf.shm_perm.gid;
347                 out->mode       = tbuf.shm_perm.mode;
348
349                 return 0;
350             }
351         case IPC_OLD:
352             {
353                 struct shmid_ds tbuf_old;
354
355                 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
356                         return -EFAULT;
357
358                 out->uid        = tbuf_old.shm_perm.uid;
359                 out->gid        = tbuf_old.shm_perm.gid;
360                 out->mode       = tbuf_old.shm_perm.mode;
361
362                 return 0;
363             }
364         default:
365                 return -EINVAL;
366         }
367 }
368
369 static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminfo64 *in, int version)
370 {
371         switch(version) {
372         case IPC_64:
373                 return copy_to_user(buf, in, sizeof(*in));
374         case IPC_OLD:
375             {
376                 struct shminfo out;
377
378                 if(in->shmmax > INT_MAX)
379                         out.shmmax = INT_MAX;
380                 else
381                         out.shmmax = (int)in->shmmax;
382
383                 out.shmmin      = in->shmmin;
384                 out.shmmni      = in->shmmni;
385                 out.shmseg      = in->shmseg;
386                 out.shmall      = in->shmall; 
387
388                 return copy_to_user(buf, &out, sizeof(out));
389             }
390         default:
391                 return -EINVAL;
392         }
393 }
394
395 static void shm_get_stat(unsigned long *rss, unsigned long *swp) 
396 {
397         int i;
398
399         *rss = 0;
400         *swp = 0;
401
402         for (i = 0; i <= shm_ids.max_id; i++) {
403                 struct shmid_kernel *shp;
404                 struct inode *inode;
405
406                 shp = shm_get(i);
407                 if(!shp)
408                         continue;
409
410                 inode = shp->shm_file->f_dentry->d_inode;
411
412                 if (is_file_hugepages(shp->shm_file)) {
413                         struct address_space *mapping = inode->i_mapping;
414                         *rss += (HPAGE_SIZE/PAGE_SIZE)*mapping->nrpages;
415                 } else {
416                         struct shmem_inode_info *info = SHMEM_I(inode);
417                         spin_lock(&info->lock);
418                         *rss += inode->i_mapping->nrpages;
419                         *swp += info->swapped;
420                         spin_unlock(&info->lock);
421                 }
422         }
423 }
424
425 asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds __user *buf)
426 {
427         struct shm_setbuf setbuf;
428         struct shmid_kernel *shp;
429         int err, version;
430
431         if (cmd < 0 || shmid < 0) {
432                 err = -EINVAL;
433                 goto out;
434         }
435
436         version = ipc_parse_version(&cmd);
437
438         switch (cmd) { /* replace with proc interface ? */
439         case IPC_INFO:
440         {
441                 struct shminfo64 shminfo;
442
443                 err = security_shm_shmctl(NULL, cmd);
444                 if (err)
445                         return err;
446
447                 memset(&shminfo,0,sizeof(shminfo));
448                 shminfo.shmmni = shminfo.shmseg = shm_ctlmni;
449                 shminfo.shmmax = shm_ctlmax;
450                 shminfo.shmall = shm_ctlall;
451
452                 shminfo.shmmin = SHMMIN;
453                 if(copy_shminfo_to_user (buf, &shminfo, version))
454                         return -EFAULT;
455                 /* reading a integer is always atomic */
456                 err= shm_ids.max_id;
457                 if(err<0)
458                         err = 0;
459                 goto out;
460         }
461         case SHM_INFO:
462         {
463                 struct shm_info shm_info;
464
465                 err = security_shm_shmctl(NULL, cmd);
466                 if (err)
467                         return err;
468
469                 memset(&shm_info,0,sizeof(shm_info));
470                 down(&shm_ids.sem);
471                 shm_info.used_ids = shm_ids.in_use;
472                 shm_get_stat (&shm_info.shm_rss, &shm_info.shm_swp);
473                 shm_info.shm_tot = shm_tot;
474                 shm_info.swap_attempts = 0;
475                 shm_info.swap_successes = 0;
476                 err = shm_ids.max_id;
477                 up(&shm_ids.sem);
478                 if(copy_to_user (buf, &shm_info, sizeof(shm_info))) {
479                         err = -EFAULT;
480                         goto out;
481                 }
482
483                 err = err < 0 ? 0 : err;
484                 goto out;
485         }
486         case SHM_STAT:
487         case IPC_STAT:
488         {
489                 struct shmid64_ds tbuf;
490                 int result;
491                 memset(&tbuf, 0, sizeof(tbuf));
492                 shp = shm_lock(shmid);
493                 if(shp==NULL) {
494                         err = -EINVAL;
495                         goto out;
496                 } else if(cmd==SHM_STAT) {
497                         err = -EINVAL;
498                         if (shmid > shm_ids.max_id)
499                                 goto out_unlock;
500                         result = shm_buildid(shmid, shp->shm_perm.seq);
501                 } else {
502                         err = shm_checkid(shp,shmid);
503                         if(err)
504                                 goto out_unlock;
505                         result = 0;
506                 }
507                 err=-EACCES;
508                 if (ipcperms (&shp->shm_perm, S_IRUGO))
509                         goto out_unlock;
510                 err = security_shm_shmctl(shp, cmd);
511                 if (err)
512                         goto out_unlock;
513                 kernel_to_ipc64_perm(&shp->shm_perm, &tbuf.shm_perm);
514                 tbuf.shm_segsz  = shp->shm_segsz;
515                 tbuf.shm_atime  = shp->shm_atim;
516                 tbuf.shm_dtime  = shp->shm_dtim;
517                 tbuf.shm_ctime  = shp->shm_ctim;
518                 tbuf.shm_cpid   = shp->shm_cprid;
519                 tbuf.shm_lpid   = shp->shm_lprid;
520                 if (!is_file_hugepages(shp->shm_file))
521                         tbuf.shm_nattch = shp->shm_nattch;
522                 else
523                         tbuf.shm_nattch = file_count(shp->shm_file) - 1;
524                 shm_unlock(shp);
525                 if(copy_shmid_to_user (buf, &tbuf, version))
526                         err = -EFAULT;
527                 else
528                         err = result;
529                 goto out;
530         }
531         case SHM_LOCK:
532         case SHM_UNLOCK:
533         {
534                 shp = shm_lock(shmid);
535                 if(shp==NULL) {
536                         err = -EINVAL;
537                         goto out;
538                 }
539                 err = shm_checkid(shp,shmid);
540                 if(err)
541                         goto out_unlock;
542
543                 if (!capable(CAP_IPC_LOCK)) {
544                         err = -EPERM;
545                         if (current->euid != shp->shm_perm.uid &&
546                             current->euid != shp->shm_perm.cuid)
547                                 goto out_unlock;
548                         if (cmd == SHM_LOCK &&
549                             !current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur)
550                                 goto out_unlock;
551                 }
552
553                 err = security_shm_shmctl(shp, cmd);
554                 if (err)
555                         goto out_unlock;
556                 
557                 if(cmd==SHM_LOCK) {
558                         struct user_struct * user = current->user;
559                         if (!is_file_hugepages(shp->shm_file)) {
560                                 err = shmem_lock(shp->shm_file, 1, user);
561                                 if (!err) {
562                                         shp->shm_perm.mode |= SHM_LOCKED;
563                                         shp->mlock_user = user;
564                                 }
565                         }
566                 } else if (!is_file_hugepages(shp->shm_file)) {
567                         shmem_lock(shp->shm_file, 0, shp->mlock_user);
568                         shp->shm_perm.mode &= ~SHM_LOCKED;
569                         shp->mlock_user = NULL;
570                 }
571                 shm_unlock(shp);
572                 goto out;
573         }
574         case IPC_RMID:
575         {
576                 /*
577                  *      We cannot simply remove the file. The SVID states
578                  *      that the block remains until the last person
579                  *      detaches from it, then is deleted. A shmat() on
580                  *      an RMID segment is legal in older Linux and if 
581                  *      we change it apps break...
582                  *
583                  *      Instead we set a destroyed flag, and then blow
584                  *      the name away when the usage hits zero.
585                  */
586                 down(&shm_ids.sem);
587                 shp = shm_lock(shmid);
588                 err = -EINVAL;
589                 if (shp == NULL) 
590                         goto out_up;
591                 err = shm_checkid(shp, shmid);
592                 if(err)
593                         goto out_unlock_up;
594
595                 if (current->euid != shp->shm_perm.uid &&
596                     current->euid != shp->shm_perm.cuid && 
597                     !capable(CAP_SYS_ADMIN)) {
598                         err=-EPERM;
599                         goto out_unlock_up;
600                 }
601
602                 err = security_shm_shmctl(shp, cmd);
603                 if (err)
604                         goto out_unlock_up;
605
606                 if (shp->shm_nattch){
607                         shp->shm_perm.mode |= SHM_DEST;
608                         /* Do not find it any more */
609                         shp->shm_perm.key = IPC_PRIVATE;
610                         shm_unlock(shp);
611                 } else
612                         shm_destroy (shp);
613                 up(&shm_ids.sem);
614                 goto out;
615         }
616
617         case IPC_SET:
618         {
619                 if (copy_shmid_from_user (&setbuf, buf, version)) {
620                         err = -EFAULT;
621                         goto out;
622                 }
623                 down(&shm_ids.sem);
624                 shp = shm_lock(shmid);
625                 err=-EINVAL;
626                 if(shp==NULL)
627                         goto out_up;
628                 if ((err = audit_ipc_perms(0, setbuf.uid, setbuf.gid, setbuf.mode, &(shp->shm_perm))))
629                         goto out_unlock_up;
630                 err = shm_checkid(shp,shmid);
631                 if(err)
632                         goto out_unlock_up;
633                 err=-EPERM;
634                 if (current->euid != shp->shm_perm.uid &&
635                     current->euid != shp->shm_perm.cuid && 
636                     !capable(CAP_SYS_ADMIN)) {
637                         goto out_unlock_up;
638                 }
639
640                 err = security_shm_shmctl(shp, cmd);
641                 if (err)
642                         goto out_unlock_up;
643                 
644                 shp->shm_perm.uid = setbuf.uid;
645                 shp->shm_perm.gid = setbuf.gid;
646                 shp->shm_perm.mode = (shp->shm_perm.mode & ~S_IRWXUGO)
647                         | (setbuf.mode & S_IRWXUGO);
648                 shp->shm_ctim = get_seconds();
649                 break;
650         }
651
652         default:
653                 err = -EINVAL;
654                 goto out;
655         }
656
657         err = 0;
658 out_unlock_up:
659         shm_unlock(shp);
660 out_up:
661         up(&shm_ids.sem);
662         goto out;
663 out_unlock:
664         shm_unlock(shp);
665 out:
666         return err;
667 }
668
669 /*
670  * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
671  *
672  * NOTE! Despite the name, this is NOT a direct system call entrypoint. The
673  * "raddr" thing points to kernel space, and there has to be a wrapper around
674  * this.
675  */
676 long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr)
677 {
678         struct shmid_kernel *shp;
679         unsigned long addr;
680         unsigned long size;
681         struct file * file;
682         int    err;
683         unsigned long flags;
684         unsigned long prot;
685         unsigned long o_flags;
686         int acc_mode;
687         void *user_addr;
688
689         if (shmid < 0) {
690                 err = -EINVAL;
691                 goto out;
692         } else if ((addr = (ulong)shmaddr)) {
693                 if (addr & (SHMLBA-1)) {
694                         if (shmflg & SHM_RND)
695                                 addr &= ~(SHMLBA-1);       /* round down */
696                         else
697 #ifndef __ARCH_FORCE_SHMLBA
698                                 if (addr & ~PAGE_MASK)
699 #endif
700                                         return -EINVAL;
701                 }
702                 flags = MAP_SHARED | MAP_FIXED;
703         } else {
704                 if ((shmflg & SHM_REMAP))
705                         return -EINVAL;
706
707                 flags = MAP_SHARED;
708         }
709
710         if (shmflg & SHM_RDONLY) {
711                 prot = PROT_READ;
712                 o_flags = O_RDONLY;
713                 acc_mode = S_IRUGO;
714         } else {
715                 prot = PROT_READ | PROT_WRITE;
716                 o_flags = O_RDWR;
717                 acc_mode = S_IRUGO | S_IWUGO;
718         }
719         if (shmflg & SHM_EXEC) {
720                 prot |= PROT_EXEC;
721                 acc_mode |= S_IXUGO;
722         }
723
724         /*
725          * We cannot rely on the fs check since SYSV IPC does have an
726          * additional creator id...
727          */
728         shp = shm_lock(shmid);
729         if(shp == NULL) {
730                 err = -EINVAL;
731                 goto out;
732         }
733         err = shm_checkid(shp,shmid);
734         if (err) {
735                 shm_unlock(shp);
736                 goto out;
737         }
738         if (ipcperms(&shp->shm_perm, acc_mode)) {
739                 shm_unlock(shp);
740                 err = -EACCES;
741                 goto out;
742         }
743
744         err = security_shm_shmat(shp, shmaddr, shmflg);
745         if (err) {
746                 shm_unlock(shp);
747                 return err;
748         }
749                 
750         file = shp->shm_file;
751         size = i_size_read(file->f_dentry->d_inode);
752         shp->shm_nattch++;
753         shm_unlock(shp);
754
755         down_write(&current->mm->mmap_sem);
756         if (addr && !(shmflg & SHM_REMAP)) {
757                 user_addr = ERR_PTR(-EINVAL);
758                 if (find_vma_intersection(current->mm, addr, addr + size))
759                         goto invalid;
760                 /*
761                  * If shm segment goes below stack, make sure there is some
762                  * space left for the stack to grow (at least 4 pages).
763                  */
764                 if (addr < current->mm->start_stack &&
765                     addr > current->mm->start_stack - size - PAGE_SIZE * 5)
766                         goto invalid;
767         }
768                 
769         user_addr = (void*) do_mmap (file, addr, size, prot, flags, 0);
770
771 invalid:
772         up_write(&current->mm->mmap_sem);
773
774         down (&shm_ids.sem);
775         if(!(shp = shm_lock(shmid)))
776                 BUG();
777         shp->shm_nattch--;
778         if(shp->shm_nattch == 0 &&
779            shp->shm_perm.mode & SHM_DEST)
780                 shm_destroy (shp);
781         else
782                 shm_unlock(shp);
783         up (&shm_ids.sem);
784
785         *raddr = (unsigned long) user_addr;
786         err = 0;
787         if (IS_ERR(user_addr))
788                 err = PTR_ERR(user_addr);
789 out:
790         return err;
791 }
792
793 asmlinkage long sys_shmat(int shmid, char __user *shmaddr, int shmflg)
794 {
795         unsigned long ret;
796         long err;
797
798         err = do_shmat(shmid, shmaddr, shmflg, &ret);
799         if (err)
800                 return err;
801         force_successful_syscall_return();
802         return (long)ret;
803 }
804
805 /*
806  * detach and kill segment if marked destroyed.
807  * The work is done in shm_close.
808  */
809 asmlinkage long sys_shmdt(char __user *shmaddr)
810 {
811         struct mm_struct *mm = current->mm;
812         struct vm_area_struct *vma, *next;
813         unsigned long addr = (unsigned long)shmaddr;
814         loff_t size = 0;
815         int retval = -EINVAL;
816
817         down_write(&mm->mmap_sem);
818
819         /*
820          * This function tries to be smart and unmap shm segments that
821          * were modified by partial mlock or munmap calls:
822          * - It first determines the size of the shm segment that should be
823          *   unmapped: It searches for a vma that is backed by shm and that
824          *   started at address shmaddr. It records it's size and then unmaps
825          *   it.
826          * - Then it unmaps all shm vmas that started at shmaddr and that
827          *   are within the initially determined size.
828          * Errors from do_munmap are ignored: the function only fails if
829          * it's called with invalid parameters or if it's called to unmap
830          * a part of a vma. Both calls in this function are for full vmas,
831          * the parameters are directly copied from the vma itself and always
832          * valid - therefore do_munmap cannot fail. (famous last words?)
833          */
834         /*
835          * If it had been mremap()'d, the starting address would not
836          * match the usual checks anyway. So assume all vma's are
837          * above the starting address given.
838          */
839         vma = find_vma(mm, addr);
840
841         while (vma) {
842                 next = vma->vm_next;
843
844                 /*
845                  * Check if the starting address would match, i.e. it's
846                  * a fragment created by mprotect() and/or munmap(), or it
847                  * otherwise it starts at this address with no hassles.
848                  */
849                 if ((vma->vm_ops == &shm_vm_ops || is_vm_hugetlb_page(vma)) &&
850                         (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) {
851
852
853                         size = vma->vm_file->f_dentry->d_inode->i_size;
854                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
855                         /*
856                          * We discovered the size of the shm segment, so
857                          * break out of here and fall through to the next
858                          * loop that uses the size information to stop
859                          * searching for matching vma's.
860                          */
861                         retval = 0;
862                         vma = next;
863                         break;
864                 }
865                 vma = next;
866         }
867
868         /*
869          * We need look no further than the maximum address a fragment
870          * could possibly have landed at. Also cast things to loff_t to
871          * prevent overflows and make comparisions vs. equal-width types.
872          */
873         size = PAGE_ALIGN(size);
874         while (vma && (loff_t)(vma->vm_end - addr) <= size) {
875                 next = vma->vm_next;
876
877                 /* finding a matching vma now does not alter retval */
878                 if ((vma->vm_ops == &shm_vm_ops || is_vm_hugetlb_page(vma)) &&
879                         (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff)
880
881                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
882                 vma = next;
883         }
884
885         up_write(&mm->mmap_sem);
886         return retval;
887 }
888
889 #ifdef CONFIG_PROC_FS
890 static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
891 {
892         struct shmid_kernel *shp = it;
893         char *format;
894
895 #define SMALL_STRING "%10d %10d  %4o %10u %5u %5u  %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
896 #define BIG_STRING   "%10d %10d  %4o %21u %5u %5u  %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
897
898         if (sizeof(size_t) <= sizeof(int))
899                 format = SMALL_STRING;
900         else
901                 format = BIG_STRING;
902         return seq_printf(s, format,
903                           shp->shm_perm.key,
904                           shp->id,
905                           shp->shm_perm.mode,
906                           shp->shm_segsz,
907                           shp->shm_cprid,
908                           shp->shm_lprid,
909                           is_file_hugepages(shp->shm_file) ? (file_count(shp->shm_file) - 1) : shp->shm_nattch,
910                           shp->shm_perm.uid,
911                           shp->shm_perm.gid,
912                           shp->shm_perm.cuid,
913                           shp->shm_perm.cgid,
914                           shp->shm_atim,
915                           shp->shm_dtim,
916                           shp->shm_ctim);
917 }
918 #endif