ipc: introduce shm_rmid_forced sysctl
[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  * support for audit of ipc object properties and permission changes
17  * Dustin Kirkland <dustin.kirkland@us.ibm.com>
18  *
19  * namespaces support
20  * OpenVZ, SWsoft Inc.
21  * Pavel Emelianov <xemul@openvz.org>
22  */
23
24 #include <linux/slab.h>
25 #include <linux/mm.h>
26 #include <linux/hugetlb.h>
27 #include <linux/shm.h>
28 #include <linux/init.h>
29 #include <linux/file.h>
30 #include <linux/mman.h>
31 #include <linux/shmem_fs.h>
32 #include <linux/security.h>
33 #include <linux/syscalls.h>
34 #include <linux/audit.h>
35 #include <linux/capability.h>
36 #include <linux/ptrace.h>
37 #include <linux/seq_file.h>
38 #include <linux/rwsem.h>
39 #include <linux/nsproxy.h>
40 #include <linux/mount.h>
41 #include <linux/ipc_namespace.h>
42
43 #include <asm/uaccess.h>
44
45 #include "util.h"
46
47 struct shm_file_data {
48         int id;
49         struct ipc_namespace *ns;
50         struct file *file;
51         const struct vm_operations_struct *vm_ops;
52 };
53
54 #define shm_file_data(file) (*((struct shm_file_data **)&(file)->private_data))
55
56 static const struct file_operations shm_file_operations;
57 static const struct vm_operations_struct shm_vm_ops;
58
59 #define shm_ids(ns)     ((ns)->ids[IPC_SHM_IDS])
60
61 #define shm_unlock(shp)                 \
62         ipc_unlock(&(shp)->shm_perm)
63
64 static int newseg(struct ipc_namespace *, struct ipc_params *);
65 static void shm_open(struct vm_area_struct *vma);
66 static void shm_close(struct vm_area_struct *vma);
67 static void shm_destroy (struct ipc_namespace *ns, struct shmid_kernel *shp);
68 #ifdef CONFIG_PROC_FS
69 static int sysvipc_shm_proc_show(struct seq_file *s, void *it);
70 #endif
71
72 void shm_init_ns(struct ipc_namespace *ns)
73 {
74         ns->shm_ctlmax = SHMMAX;
75         ns->shm_ctlall = SHMALL;
76         ns->shm_ctlmni = SHMMNI;
77         ns->shm_rmid_forced = 0;
78         ns->shm_tot = 0;
79         ipc_init_ids(&shm_ids(ns));
80 }
81
82 /*
83  * Called with shm_ids.rw_mutex (writer) and the shp structure locked.
84  * Only shm_ids.rw_mutex remains locked on exit.
85  */
86 static void do_shm_rmid(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
87 {
88         struct shmid_kernel *shp;
89         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
90
91         if (shp->shm_nattch){
92                 shp->shm_perm.mode |= SHM_DEST;
93                 /* Do not find it any more */
94                 shp->shm_perm.key = IPC_PRIVATE;
95                 shm_unlock(shp);
96         } else
97                 shm_destroy(ns, shp);
98 }
99
100 #ifdef CONFIG_IPC_NS
101 void shm_exit_ns(struct ipc_namespace *ns)
102 {
103         free_ipcs(ns, &shm_ids(ns), do_shm_rmid);
104         idr_destroy(&ns->ids[IPC_SHM_IDS].ipcs_idr);
105 }
106 #endif
107
108 void __init shm_init (void)
109 {
110         shm_init_ns(&init_ipc_ns);
111         ipc_init_proc_interface("sysvipc/shm",
112 #if BITS_PER_LONG <= 32
113                                 "       key      shmid perms       size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime        rss       swap\n",
114 #else
115                                 "       key      shmid perms                  size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime                   rss                  swap\n",
116 #endif
117                                 IPC_SHM_IDS, sysvipc_shm_proc_show);
118 }
119
120 /*
121  * shm_lock_(check_) routines are called in the paths where the rw_mutex
122  * is not necessarily held.
123  */
124 static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id)
125 {
126         struct kern_ipc_perm *ipcp = ipc_lock(&shm_ids(ns), id);
127
128         if (IS_ERR(ipcp))
129                 return (struct shmid_kernel *)ipcp;
130
131         return container_of(ipcp, struct shmid_kernel, shm_perm);
132 }
133
134 static inline struct shmid_kernel *shm_lock_check(struct ipc_namespace *ns,
135                                                 int id)
136 {
137         struct kern_ipc_perm *ipcp = ipc_lock_check(&shm_ids(ns), id);
138
139         if (IS_ERR(ipcp))
140                 return (struct shmid_kernel *)ipcp;
141
142         return container_of(ipcp, struct shmid_kernel, shm_perm);
143 }
144
145 static inline void shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *s)
146 {
147         ipc_rmid(&shm_ids(ns), &s->shm_perm);
148 }
149
150
151 /* This is called by fork, once for every shm attach. */
152 static void shm_open(struct vm_area_struct *vma)
153 {
154         struct file *file = vma->vm_file;
155         struct shm_file_data *sfd = shm_file_data(file);
156         struct shmid_kernel *shp;
157
158         shp = shm_lock(sfd->ns, sfd->id);
159         BUG_ON(IS_ERR(shp));
160         shp->shm_atim = get_seconds();
161         shp->shm_lprid = task_tgid_vnr(current);
162         shp->shm_nattch++;
163         shm_unlock(shp);
164 }
165
166 /*
167  * shm_destroy - free the struct shmid_kernel
168  *
169  * @ns: namespace
170  * @shp: struct to free
171  *
172  * It has to be called with shp and shm_ids.rw_mutex (writer) locked,
173  * but returns with shp unlocked and freed.
174  */
175 static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
176 {
177         ns->shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT;
178         shm_rmid(ns, shp);
179         shm_unlock(shp);
180         if (!is_file_hugepages(shp->shm_file))
181                 shmem_lock(shp->shm_file, 0, shp->mlock_user);
182         else if (shp->mlock_user)
183                 user_shm_unlock(shp->shm_file->f_path.dentry->d_inode->i_size,
184                                                 shp->mlock_user);
185         fput (shp->shm_file);
186         security_shm_free(shp);
187         ipc_rcu_putref(shp);
188 }
189
190 /*
191  * shm_may_destroy - identifies whether shm segment should be destroyed now
192  *
193  * Returns true if and only if there are no active users of the segment and
194  * one of the following is true:
195  *
196  * 1) shmctl(id, IPC_RMID, NULL) was called for this shp
197  *
198  * 2) sysctl kernel.shm_rmid_forced is set to 1.
199  */
200 static bool shm_may_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
201 {
202         return (shp->shm_nattch == 0) &&
203                (ns->shm_rmid_forced ||
204                 (shp->shm_perm.mode & SHM_DEST));
205 }
206
207 /*
208  * remove the attach descriptor vma.
209  * free memory for segment if it is marked destroyed.
210  * The descriptor has already been removed from the current->mm->mmap list
211  * and will later be kfree()d.
212  */
213 static void shm_close(struct vm_area_struct *vma)
214 {
215         struct file * file = vma->vm_file;
216         struct shm_file_data *sfd = shm_file_data(file);
217         struct shmid_kernel *shp;
218         struct ipc_namespace *ns = sfd->ns;
219
220         down_write(&shm_ids(ns).rw_mutex);
221         /* remove from the list of attaches of the shm segment */
222         shp = shm_lock(ns, sfd->id);
223         BUG_ON(IS_ERR(shp));
224         shp->shm_lprid = task_tgid_vnr(current);
225         shp->shm_dtim = get_seconds();
226         shp->shm_nattch--;
227         if (shm_may_destroy(ns, shp))
228                 shm_destroy(ns, shp);
229         else
230                 shm_unlock(shp);
231         up_write(&shm_ids(ns).rw_mutex);
232 }
233
234 static int shm_try_destroy_current(int id, void *p, void *data)
235 {
236         struct ipc_namespace *ns = data;
237         struct shmid_kernel *shp = shm_lock(ns, id);
238
239         if (IS_ERR(shp))
240                 return 0;
241
242         if (shp->shm_cprid != task_tgid_vnr(current)) {
243                 shm_unlock(shp);
244                 return 0;
245         }
246
247         if (shm_may_destroy(ns, shp))
248                 shm_destroy(ns, shp);
249         else
250                 shm_unlock(shp);
251         return 0;
252 }
253
254 static int shm_try_destroy_orphaned(int id, void *p, void *data)
255 {
256         struct ipc_namespace *ns = data;
257         struct shmid_kernel *shp = shm_lock(ns, id);
258         struct task_struct *task;
259
260         if (IS_ERR(shp))
261                 return 0;
262
263         /*
264          * We want to destroy segments without users and with already
265          * exit'ed originating process.
266          *
267          * XXX: the originating process may exist in another pid namespace.
268          */
269         task = find_task_by_vpid(shp->shm_cprid);
270         if (task != NULL) {
271                 shm_unlock(shp);
272                 return 0;
273         }
274
275         if (shm_may_destroy(ns, shp))
276                 shm_destroy(ns, shp);
277         else
278                 shm_unlock(shp);
279         return 0;
280 }
281
282 void shm_destroy_orphaned(struct ipc_namespace *ns)
283 {
284         down_write(&shm_ids(ns).rw_mutex);
285         idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_orphaned, ns);
286         up_write(&shm_ids(ns).rw_mutex);
287 }
288
289
290 void exit_shm(struct task_struct *task)
291 {
292         struct nsproxy *nsp = task->nsproxy;
293         struct ipc_namespace *ns;
294
295         if (!nsp)
296                 return;
297         ns = nsp->ipc_ns;
298         if (!ns || !ns->shm_rmid_forced)
299                 return;
300
301         /* Destroy all already created segments, but not mapped yet */
302         down_write(&shm_ids(ns).rw_mutex);
303         idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_current, ns);
304         up_write(&shm_ids(ns).rw_mutex);
305 }
306
307 static int shm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
308 {
309         struct file *file = vma->vm_file;
310         struct shm_file_data *sfd = shm_file_data(file);
311
312         return sfd->vm_ops->fault(vma, vmf);
313 }
314
315 #ifdef CONFIG_NUMA
316 static int shm_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
317 {
318         struct file *file = vma->vm_file;
319         struct shm_file_data *sfd = shm_file_data(file);
320         int err = 0;
321         if (sfd->vm_ops->set_policy)
322                 err = sfd->vm_ops->set_policy(vma, new);
323         return err;
324 }
325
326 static struct mempolicy *shm_get_policy(struct vm_area_struct *vma,
327                                         unsigned long addr)
328 {
329         struct file *file = vma->vm_file;
330         struct shm_file_data *sfd = shm_file_data(file);
331         struct mempolicy *pol = NULL;
332
333         if (sfd->vm_ops->get_policy)
334                 pol = sfd->vm_ops->get_policy(vma, addr);
335         else if (vma->vm_policy)
336                 pol = vma->vm_policy;
337
338         return pol;
339 }
340 #endif
341
342 static int shm_mmap(struct file * file, struct vm_area_struct * vma)
343 {
344         struct shm_file_data *sfd = shm_file_data(file);
345         int ret;
346
347         ret = sfd->file->f_op->mmap(sfd->file, vma);
348         if (ret != 0)
349                 return ret;
350         sfd->vm_ops = vma->vm_ops;
351 #ifdef CONFIG_MMU
352         BUG_ON(!sfd->vm_ops->fault);
353 #endif
354         vma->vm_ops = &shm_vm_ops;
355         shm_open(vma);
356
357         return ret;
358 }
359
360 static int shm_release(struct inode *ino, struct file *file)
361 {
362         struct shm_file_data *sfd = shm_file_data(file);
363
364         put_ipc_ns(sfd->ns);
365         shm_file_data(file) = NULL;
366         kfree(sfd);
367         return 0;
368 }
369
370 static int shm_fsync(struct file *file, loff_t start, loff_t end, int datasync)
371 {
372         struct shm_file_data *sfd = shm_file_data(file);
373
374         if (!sfd->file->f_op->fsync)
375                 return -EINVAL;
376         return sfd->file->f_op->fsync(sfd->file, start, end, datasync);
377 }
378
379 static unsigned long shm_get_unmapped_area(struct file *file,
380         unsigned long addr, unsigned long len, unsigned long pgoff,
381         unsigned long flags)
382 {
383         struct shm_file_data *sfd = shm_file_data(file);
384         return sfd->file->f_op->get_unmapped_area(sfd->file, addr, len,
385                                                 pgoff, flags);
386 }
387
388 static const struct file_operations shm_file_operations = {
389         .mmap           = shm_mmap,
390         .fsync          = shm_fsync,
391         .release        = shm_release,
392 #ifndef CONFIG_MMU
393         .get_unmapped_area      = shm_get_unmapped_area,
394 #endif
395         .llseek         = noop_llseek,
396 };
397
398 static const struct file_operations shm_file_operations_huge = {
399         .mmap           = shm_mmap,
400         .fsync          = shm_fsync,
401         .release        = shm_release,
402         .get_unmapped_area      = shm_get_unmapped_area,
403         .llseek         = noop_llseek,
404 };
405
406 int is_file_shm_hugepages(struct file *file)
407 {
408         return file->f_op == &shm_file_operations_huge;
409 }
410
411 static const struct vm_operations_struct shm_vm_ops = {
412         .open   = shm_open,     /* callback for a new vm-area open */
413         .close  = shm_close,    /* callback for when the vm-area is released */
414         .fault  = shm_fault,
415 #if defined(CONFIG_NUMA)
416         .set_policy = shm_set_policy,
417         .get_policy = shm_get_policy,
418 #endif
419 };
420
421 /**
422  * newseg - Create a new shared memory segment
423  * @ns: namespace
424  * @params: ptr to the structure that contains key, size and shmflg
425  *
426  * Called with shm_ids.rw_mutex held as a writer.
427  */
428
429 static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
430 {
431         key_t key = params->key;
432         int shmflg = params->flg;
433         size_t size = params->u.size;
434         int error;
435         struct shmid_kernel *shp;
436         int numpages = (size + PAGE_SIZE -1) >> PAGE_SHIFT;
437         struct file * file;
438         char name[13];
439         int id;
440         vm_flags_t acctflag = 0;
441
442         if (size < SHMMIN || size > ns->shm_ctlmax)
443                 return -EINVAL;
444
445         if (ns->shm_tot + numpages > ns->shm_ctlall)
446                 return -ENOSPC;
447
448         shp = ipc_rcu_alloc(sizeof(*shp));
449         if (!shp)
450                 return -ENOMEM;
451
452         shp->shm_perm.key = key;
453         shp->shm_perm.mode = (shmflg & S_IRWXUGO);
454         shp->mlock_user = NULL;
455
456         shp->shm_perm.security = NULL;
457         error = security_shm_alloc(shp);
458         if (error) {
459                 ipc_rcu_putref(shp);
460                 return error;
461         }
462
463         sprintf (name, "SYSV%08x", key);
464         if (shmflg & SHM_HUGETLB) {
465                 /* hugetlb_file_setup applies strict accounting */
466                 if (shmflg & SHM_NORESERVE)
467                         acctflag = VM_NORESERVE;
468                 file = hugetlb_file_setup(name, size, acctflag,
469                                         &shp->mlock_user, HUGETLB_SHMFS_INODE);
470         } else {
471                 /*
472                  * Do not allow no accounting for OVERCOMMIT_NEVER, even
473                  * if it's asked for.
474                  */
475                 if  ((shmflg & SHM_NORESERVE) &&
476                                 sysctl_overcommit_memory != OVERCOMMIT_NEVER)
477                         acctflag = VM_NORESERVE;
478                 file = shmem_file_setup(name, size, acctflag);
479         }
480         error = PTR_ERR(file);
481         if (IS_ERR(file))
482                 goto no_file;
483
484         id = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni);
485         if (id < 0) {
486                 error = id;
487                 goto no_id;
488         }
489
490         shp->shm_cprid = task_tgid_vnr(current);
491         shp->shm_lprid = 0;
492         shp->shm_atim = shp->shm_dtim = 0;
493         shp->shm_ctim = get_seconds();
494         shp->shm_segsz = size;
495         shp->shm_nattch = 0;
496         shp->shm_file = file;
497         /*
498          * shmid gets reported as "inode#" in /proc/pid/maps.
499          * proc-ps tools use this. Changing this will break them.
500          */
501         file->f_dentry->d_inode->i_ino = shp->shm_perm.id;
502
503         ns->shm_tot += numpages;
504         error = shp->shm_perm.id;
505         shm_unlock(shp);
506         return error;
507
508 no_id:
509         if (is_file_hugepages(file) && shp->mlock_user)
510                 user_shm_unlock(size, shp->mlock_user);
511         fput(file);
512 no_file:
513         security_shm_free(shp);
514         ipc_rcu_putref(shp);
515         return error;
516 }
517
518 /*
519  * Called with shm_ids.rw_mutex and ipcp locked.
520  */
521 static inline int shm_security(struct kern_ipc_perm *ipcp, int shmflg)
522 {
523         struct shmid_kernel *shp;
524
525         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
526         return security_shm_associate(shp, shmflg);
527 }
528
529 /*
530  * Called with shm_ids.rw_mutex and ipcp locked.
531  */
532 static inline int shm_more_checks(struct kern_ipc_perm *ipcp,
533                                 struct ipc_params *params)
534 {
535         struct shmid_kernel *shp;
536
537         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
538         if (shp->shm_segsz < params->u.size)
539                 return -EINVAL;
540
541         return 0;
542 }
543
544 SYSCALL_DEFINE3(shmget, key_t, key, size_t, size, int, shmflg)
545 {
546         struct ipc_namespace *ns;
547         struct ipc_ops shm_ops;
548         struct ipc_params shm_params;
549
550         ns = current->nsproxy->ipc_ns;
551
552         shm_ops.getnew = newseg;
553         shm_ops.associate = shm_security;
554         shm_ops.more_checks = shm_more_checks;
555
556         shm_params.key = key;
557         shm_params.flg = shmflg;
558         shm_params.u.size = size;
559
560         return ipcget(ns, &shm_ids(ns), &shm_ops, &shm_params);
561 }
562
563 static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version)
564 {
565         switch(version) {
566         case IPC_64:
567                 return copy_to_user(buf, in, sizeof(*in));
568         case IPC_OLD:
569             {
570                 struct shmid_ds out;
571
572                 memset(&out, 0, sizeof(out));
573                 ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
574                 out.shm_segsz   = in->shm_segsz;
575                 out.shm_atime   = in->shm_atime;
576                 out.shm_dtime   = in->shm_dtime;
577                 out.shm_ctime   = in->shm_ctime;
578                 out.shm_cpid    = in->shm_cpid;
579                 out.shm_lpid    = in->shm_lpid;
580                 out.shm_nattch  = in->shm_nattch;
581
582                 return copy_to_user(buf, &out, sizeof(out));
583             }
584         default:
585                 return -EINVAL;
586         }
587 }
588
589 static inline unsigned long
590 copy_shmid_from_user(struct shmid64_ds *out, void __user *buf, int version)
591 {
592         switch(version) {
593         case IPC_64:
594                 if (copy_from_user(out, buf, sizeof(*out)))
595                         return -EFAULT;
596                 return 0;
597         case IPC_OLD:
598             {
599                 struct shmid_ds tbuf_old;
600
601                 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
602                         return -EFAULT;
603
604                 out->shm_perm.uid       = tbuf_old.shm_perm.uid;
605                 out->shm_perm.gid       = tbuf_old.shm_perm.gid;
606                 out->shm_perm.mode      = tbuf_old.shm_perm.mode;
607
608                 return 0;
609             }
610         default:
611                 return -EINVAL;
612         }
613 }
614
615 static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminfo64 *in, int version)
616 {
617         switch(version) {
618         case IPC_64:
619                 return copy_to_user(buf, in, sizeof(*in));
620         case IPC_OLD:
621             {
622                 struct shminfo out;
623
624                 if(in->shmmax > INT_MAX)
625                         out.shmmax = INT_MAX;
626                 else
627                         out.shmmax = (int)in->shmmax;
628
629                 out.shmmin      = in->shmmin;
630                 out.shmmni      = in->shmmni;
631                 out.shmseg      = in->shmseg;
632                 out.shmall      = in->shmall; 
633
634                 return copy_to_user(buf, &out, sizeof(out));
635             }
636         default:
637                 return -EINVAL;
638         }
639 }
640
641 /*
642  * Calculate and add used RSS and swap pages of a shm.
643  * Called with shm_ids.rw_mutex held as a reader
644  */
645 static void shm_add_rss_swap(struct shmid_kernel *shp,
646         unsigned long *rss_add, unsigned long *swp_add)
647 {
648         struct inode *inode;
649
650         inode = shp->shm_file->f_path.dentry->d_inode;
651
652         if (is_file_hugepages(shp->shm_file)) {
653                 struct address_space *mapping = inode->i_mapping;
654                 struct hstate *h = hstate_file(shp->shm_file);
655                 *rss_add += pages_per_huge_page(h) * mapping->nrpages;
656         } else {
657 #ifdef CONFIG_SHMEM
658                 struct shmem_inode_info *info = SHMEM_I(inode);
659                 spin_lock(&info->lock);
660                 *rss_add += inode->i_mapping->nrpages;
661                 *swp_add += info->swapped;
662                 spin_unlock(&info->lock);
663 #else
664                 *rss_add += inode->i_mapping->nrpages;
665 #endif
666         }
667 }
668
669 /*
670  * Called with shm_ids.rw_mutex held as a reader
671  */
672 static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
673                 unsigned long *swp)
674 {
675         int next_id;
676         int total, in_use;
677
678         *rss = 0;
679         *swp = 0;
680
681         in_use = shm_ids(ns).in_use;
682
683         for (total = 0, next_id = 0; total < in_use; next_id++) {
684                 struct kern_ipc_perm *ipc;
685                 struct shmid_kernel *shp;
686
687                 ipc = idr_find(&shm_ids(ns).ipcs_idr, next_id);
688                 if (ipc == NULL)
689                         continue;
690                 shp = container_of(ipc, struct shmid_kernel, shm_perm);
691
692                 shm_add_rss_swap(shp, rss, swp);
693
694                 total++;
695         }
696 }
697
698 /*
699  * This function handles some shmctl commands which require the rw_mutex
700  * to be held in write mode.
701  * NOTE: no locks must be held, the rw_mutex is taken inside this function.
702  */
703 static int shmctl_down(struct ipc_namespace *ns, int shmid, int cmd,
704                        struct shmid_ds __user *buf, int version)
705 {
706         struct kern_ipc_perm *ipcp;
707         struct shmid64_ds shmid64;
708         struct shmid_kernel *shp;
709         int err;
710
711         if (cmd == IPC_SET) {
712                 if (copy_shmid_from_user(&shmid64, buf, version))
713                         return -EFAULT;
714         }
715
716         ipcp = ipcctl_pre_down(ns, &shm_ids(ns), shmid, cmd,
717                                &shmid64.shm_perm, 0);
718         if (IS_ERR(ipcp))
719                 return PTR_ERR(ipcp);
720
721         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
722
723         err = security_shm_shmctl(shp, cmd);
724         if (err)
725                 goto out_unlock;
726         switch (cmd) {
727         case IPC_RMID:
728                 do_shm_rmid(ns, ipcp);
729                 goto out_up;
730         case IPC_SET:
731                 ipc_update_perm(&shmid64.shm_perm, ipcp);
732                 shp->shm_ctim = get_seconds();
733                 break;
734         default:
735                 err = -EINVAL;
736         }
737 out_unlock:
738         shm_unlock(shp);
739 out_up:
740         up_write(&shm_ids(ns).rw_mutex);
741         return err;
742 }
743
744 SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
745 {
746         struct shmid_kernel *shp;
747         int err, version;
748         struct ipc_namespace *ns;
749
750         if (cmd < 0 || shmid < 0) {
751                 err = -EINVAL;
752                 goto out;
753         }
754
755         version = ipc_parse_version(&cmd);
756         ns = current->nsproxy->ipc_ns;
757
758         switch (cmd) { /* replace with proc interface ? */
759         case IPC_INFO:
760         {
761                 struct shminfo64 shminfo;
762
763                 err = security_shm_shmctl(NULL, cmd);
764                 if (err)
765                         return err;
766
767                 memset(&shminfo, 0, sizeof(shminfo));
768                 shminfo.shmmni = shminfo.shmseg = ns->shm_ctlmni;
769                 shminfo.shmmax = ns->shm_ctlmax;
770                 shminfo.shmall = ns->shm_ctlall;
771
772                 shminfo.shmmin = SHMMIN;
773                 if(copy_shminfo_to_user (buf, &shminfo, version))
774                         return -EFAULT;
775
776                 down_read(&shm_ids(ns).rw_mutex);
777                 err = ipc_get_maxid(&shm_ids(ns));
778                 up_read(&shm_ids(ns).rw_mutex);
779
780                 if(err<0)
781                         err = 0;
782                 goto out;
783         }
784         case SHM_INFO:
785         {
786                 struct shm_info shm_info;
787
788                 err = security_shm_shmctl(NULL, cmd);
789                 if (err)
790                         return err;
791
792                 memset(&shm_info, 0, sizeof(shm_info));
793                 down_read(&shm_ids(ns).rw_mutex);
794                 shm_info.used_ids = shm_ids(ns).in_use;
795                 shm_get_stat (ns, &shm_info.shm_rss, &shm_info.shm_swp);
796                 shm_info.shm_tot = ns->shm_tot;
797                 shm_info.swap_attempts = 0;
798                 shm_info.swap_successes = 0;
799                 err = ipc_get_maxid(&shm_ids(ns));
800                 up_read(&shm_ids(ns).rw_mutex);
801                 if (copy_to_user(buf, &shm_info, sizeof(shm_info))) {
802                         err = -EFAULT;
803                         goto out;
804                 }
805
806                 err = err < 0 ? 0 : err;
807                 goto out;
808         }
809         case SHM_STAT:
810         case IPC_STAT:
811         {
812                 struct shmid64_ds tbuf;
813                 int result;
814
815                 if (cmd == SHM_STAT) {
816                         shp = shm_lock(ns, shmid);
817                         if (IS_ERR(shp)) {
818                                 err = PTR_ERR(shp);
819                                 goto out;
820                         }
821                         result = shp->shm_perm.id;
822                 } else {
823                         shp = shm_lock_check(ns, shmid);
824                         if (IS_ERR(shp)) {
825                                 err = PTR_ERR(shp);
826                                 goto out;
827                         }
828                         result = 0;
829                 }
830                 err = -EACCES;
831                 if (ipcperms(ns, &shp->shm_perm, S_IRUGO))
832                         goto out_unlock;
833                 err = security_shm_shmctl(shp, cmd);
834                 if (err)
835                         goto out_unlock;
836                 memset(&tbuf, 0, sizeof(tbuf));
837                 kernel_to_ipc64_perm(&shp->shm_perm, &tbuf.shm_perm);
838                 tbuf.shm_segsz  = shp->shm_segsz;
839                 tbuf.shm_atime  = shp->shm_atim;
840                 tbuf.shm_dtime  = shp->shm_dtim;
841                 tbuf.shm_ctime  = shp->shm_ctim;
842                 tbuf.shm_cpid   = shp->shm_cprid;
843                 tbuf.shm_lpid   = shp->shm_lprid;
844                 tbuf.shm_nattch = shp->shm_nattch;
845                 shm_unlock(shp);
846                 if(copy_shmid_to_user (buf, &tbuf, version))
847                         err = -EFAULT;
848                 else
849                         err = result;
850                 goto out;
851         }
852         case SHM_LOCK:
853         case SHM_UNLOCK:
854         {
855                 struct file *uninitialized_var(shm_file);
856
857                 lru_add_drain_all();  /* drain pagevecs to lru lists */
858
859                 shp = shm_lock_check(ns, shmid);
860                 if (IS_ERR(shp)) {
861                         err = PTR_ERR(shp);
862                         goto out;
863                 }
864
865                 audit_ipc_obj(&(shp->shm_perm));
866
867                 if (!ns_capable(ns->user_ns, CAP_IPC_LOCK)) {
868                         uid_t euid = current_euid();
869                         err = -EPERM;
870                         if (euid != shp->shm_perm.uid &&
871                             euid != shp->shm_perm.cuid)
872                                 goto out_unlock;
873                         if (cmd == SHM_LOCK && !rlimit(RLIMIT_MEMLOCK))
874                                 goto out_unlock;
875                 }
876
877                 err = security_shm_shmctl(shp, cmd);
878                 if (err)
879                         goto out_unlock;
880                 
881                 if(cmd==SHM_LOCK) {
882                         struct user_struct *user = current_user();
883                         if (!is_file_hugepages(shp->shm_file)) {
884                                 err = shmem_lock(shp->shm_file, 1, user);
885                                 if (!err && !(shp->shm_perm.mode & SHM_LOCKED)){
886                                         shp->shm_perm.mode |= SHM_LOCKED;
887                                         shp->mlock_user = user;
888                                 }
889                         }
890                 } else if (!is_file_hugepages(shp->shm_file)) {
891                         shmem_lock(shp->shm_file, 0, shp->mlock_user);
892                         shp->shm_perm.mode &= ~SHM_LOCKED;
893                         shp->mlock_user = NULL;
894                 }
895                 shm_unlock(shp);
896                 goto out;
897         }
898         case IPC_RMID:
899         case IPC_SET:
900                 err = shmctl_down(ns, shmid, cmd, buf, version);
901                 return err;
902         default:
903                 return -EINVAL;
904         }
905
906 out_unlock:
907         shm_unlock(shp);
908 out:
909         return err;
910 }
911
912 /*
913  * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
914  *
915  * NOTE! Despite the name, this is NOT a direct system call entrypoint. The
916  * "raddr" thing points to kernel space, and there has to be a wrapper around
917  * this.
918  */
919 long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr)
920 {
921         struct shmid_kernel *shp;
922         unsigned long addr;
923         unsigned long size;
924         struct file * file;
925         int    err;
926         unsigned long flags;
927         unsigned long prot;
928         int acc_mode;
929         unsigned long user_addr;
930         struct ipc_namespace *ns;
931         struct shm_file_data *sfd;
932         struct path path;
933         fmode_t f_mode;
934
935         err = -EINVAL;
936         if (shmid < 0)
937                 goto out;
938         else if ((addr = (ulong)shmaddr)) {
939                 if (addr & (SHMLBA-1)) {
940                         if (shmflg & SHM_RND)
941                                 addr &= ~(SHMLBA-1);       /* round down */
942                         else
943 #ifndef __ARCH_FORCE_SHMLBA
944                                 if (addr & ~PAGE_MASK)
945 #endif
946                                         goto out;
947                 }
948                 flags = MAP_SHARED | MAP_FIXED;
949         } else {
950                 if ((shmflg & SHM_REMAP))
951                         goto out;
952
953                 flags = MAP_SHARED;
954         }
955
956         if (shmflg & SHM_RDONLY) {
957                 prot = PROT_READ;
958                 acc_mode = S_IRUGO;
959                 f_mode = FMODE_READ;
960         } else {
961                 prot = PROT_READ | PROT_WRITE;
962                 acc_mode = S_IRUGO | S_IWUGO;
963                 f_mode = FMODE_READ | FMODE_WRITE;
964         }
965         if (shmflg & SHM_EXEC) {
966                 prot |= PROT_EXEC;
967                 acc_mode |= S_IXUGO;
968         }
969
970         /*
971          * We cannot rely on the fs check since SYSV IPC does have an
972          * additional creator id...
973          */
974         ns = current->nsproxy->ipc_ns;
975         shp = shm_lock_check(ns, shmid);
976         if (IS_ERR(shp)) {
977                 err = PTR_ERR(shp);
978                 goto out;
979         }
980
981         err = -EACCES;
982         if (ipcperms(ns, &shp->shm_perm, acc_mode))
983                 goto out_unlock;
984
985         err = security_shm_shmat(shp, shmaddr, shmflg);
986         if (err)
987                 goto out_unlock;
988
989         path = shp->shm_file->f_path;
990         path_get(&path);
991         shp->shm_nattch++;
992         size = i_size_read(path.dentry->d_inode);
993         shm_unlock(shp);
994
995         err = -ENOMEM;
996         sfd = kzalloc(sizeof(*sfd), GFP_KERNEL);
997         if (!sfd)
998                 goto out_put_dentry;
999
1000         file = alloc_file(&path, f_mode,
1001                           is_file_hugepages(shp->shm_file) ?
1002                                 &shm_file_operations_huge :
1003                                 &shm_file_operations);
1004         if (!file)
1005                 goto out_free;
1006
1007         file->private_data = sfd;
1008         file->f_mapping = shp->shm_file->f_mapping;
1009         sfd->id = shp->shm_perm.id;
1010         sfd->ns = get_ipc_ns(ns);
1011         sfd->file = shp->shm_file;
1012         sfd->vm_ops = NULL;
1013
1014         down_write(&current->mm->mmap_sem);
1015         if (addr && !(shmflg & SHM_REMAP)) {
1016                 err = -EINVAL;
1017                 if (find_vma_intersection(current->mm, addr, addr + size))
1018                         goto invalid;
1019                 /*
1020                  * If shm segment goes below stack, make sure there is some
1021                  * space left for the stack to grow (at least 4 pages).
1022                  */
1023                 if (addr < current->mm->start_stack &&
1024                     addr > current->mm->start_stack - size - PAGE_SIZE * 5)
1025                         goto invalid;
1026         }
1027                 
1028         user_addr = do_mmap (file, addr, size, prot, flags, 0);
1029         *raddr = user_addr;
1030         err = 0;
1031         if (IS_ERR_VALUE(user_addr))
1032                 err = (long)user_addr;
1033 invalid:
1034         up_write(&current->mm->mmap_sem);
1035
1036         fput(file);
1037
1038 out_nattch:
1039         down_write(&shm_ids(ns).rw_mutex);
1040         shp = shm_lock(ns, shmid);
1041         BUG_ON(IS_ERR(shp));
1042         shp->shm_nattch--;
1043         if (shm_may_destroy(ns, shp))
1044                 shm_destroy(ns, shp);
1045         else
1046                 shm_unlock(shp);
1047         up_write(&shm_ids(ns).rw_mutex);
1048
1049 out:
1050         return err;
1051
1052 out_unlock:
1053         shm_unlock(shp);
1054         goto out;
1055
1056 out_free:
1057         kfree(sfd);
1058 out_put_dentry:
1059         path_put(&path);
1060         goto out_nattch;
1061 }
1062
1063 SYSCALL_DEFINE3(shmat, int, shmid, char __user *, shmaddr, int, shmflg)
1064 {
1065         unsigned long ret;
1066         long err;
1067
1068         err = do_shmat(shmid, shmaddr, shmflg, &ret);
1069         if (err)
1070                 return err;
1071         force_successful_syscall_return();
1072         return (long)ret;
1073 }
1074
1075 /*
1076  * detach and kill segment if marked destroyed.
1077  * The work is done in shm_close.
1078  */
1079 SYSCALL_DEFINE1(shmdt, char __user *, shmaddr)
1080 {
1081         struct mm_struct *mm = current->mm;
1082         struct vm_area_struct *vma;
1083         unsigned long addr = (unsigned long)shmaddr;
1084         int retval = -EINVAL;
1085 #ifdef CONFIG_MMU
1086         loff_t size = 0;
1087         struct vm_area_struct *next;
1088 #endif
1089
1090         if (addr & ~PAGE_MASK)
1091                 return retval;
1092
1093         down_write(&mm->mmap_sem);
1094
1095         /*
1096          * This function tries to be smart and unmap shm segments that
1097          * were modified by partial mlock or munmap calls:
1098          * - It first determines the size of the shm segment that should be
1099          *   unmapped: It searches for a vma that is backed by shm and that
1100          *   started at address shmaddr. It records it's size and then unmaps
1101          *   it.
1102          * - Then it unmaps all shm vmas that started at shmaddr and that
1103          *   are within the initially determined size.
1104          * Errors from do_munmap are ignored: the function only fails if
1105          * it's called with invalid parameters or if it's called to unmap
1106          * a part of a vma. Both calls in this function are for full vmas,
1107          * the parameters are directly copied from the vma itself and always
1108          * valid - therefore do_munmap cannot fail. (famous last words?)
1109          */
1110         /*
1111          * If it had been mremap()'d, the starting address would not
1112          * match the usual checks anyway. So assume all vma's are
1113          * above the starting address given.
1114          */
1115         vma = find_vma(mm, addr);
1116
1117 #ifdef CONFIG_MMU
1118         while (vma) {
1119                 next = vma->vm_next;
1120
1121                 /*
1122                  * Check if the starting address would match, i.e. it's
1123                  * a fragment created by mprotect() and/or munmap(), or it
1124                  * otherwise it starts at this address with no hassles.
1125                  */
1126                 if ((vma->vm_ops == &shm_vm_ops) &&
1127                         (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) {
1128
1129
1130                         size = vma->vm_file->f_path.dentry->d_inode->i_size;
1131                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
1132                         /*
1133                          * We discovered the size of the shm segment, so
1134                          * break out of here and fall through to the next
1135                          * loop that uses the size information to stop
1136                          * searching for matching vma's.
1137                          */
1138                         retval = 0;
1139                         vma = next;
1140                         break;
1141                 }
1142                 vma = next;
1143         }
1144
1145         /*
1146          * We need look no further than the maximum address a fragment
1147          * could possibly have landed at. Also cast things to loff_t to
1148          * prevent overflows and make comparisons vs. equal-width types.
1149          */
1150         size = PAGE_ALIGN(size);
1151         while (vma && (loff_t)(vma->vm_end - addr) <= size) {
1152                 next = vma->vm_next;
1153
1154                 /* finding a matching vma now does not alter retval */
1155                 if ((vma->vm_ops == &shm_vm_ops) &&
1156                         (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff)
1157
1158                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
1159                 vma = next;
1160         }
1161
1162 #else /* CONFIG_MMU */
1163         /* under NOMMU conditions, the exact address to be destroyed must be
1164          * given */
1165         retval = -EINVAL;
1166         if (vma->vm_start == addr && vma->vm_ops == &shm_vm_ops) {
1167                 do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
1168                 retval = 0;
1169         }
1170
1171 #endif
1172
1173         up_write(&mm->mmap_sem);
1174         return retval;
1175 }
1176
1177 #ifdef CONFIG_PROC_FS
1178 static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
1179 {
1180         struct shmid_kernel *shp = it;
1181         unsigned long rss = 0, swp = 0;
1182
1183         shm_add_rss_swap(shp, &rss, &swp);
1184
1185 #if BITS_PER_LONG <= 32
1186 #define SIZE_SPEC "%10lu"
1187 #else
1188 #define SIZE_SPEC "%21lu"
1189 #endif
1190
1191         return seq_printf(s,
1192                           "%10d %10d  %4o " SIZE_SPEC " %5u %5u  "
1193                           "%5lu %5u %5u %5u %5u %10lu %10lu %10lu "
1194                           SIZE_SPEC " " SIZE_SPEC "\n",
1195                           shp->shm_perm.key,
1196                           shp->shm_perm.id,
1197                           shp->shm_perm.mode,
1198                           shp->shm_segsz,
1199                           shp->shm_cprid,
1200                           shp->shm_lprid,
1201                           shp->shm_nattch,
1202                           shp->shm_perm.uid,
1203                           shp->shm_perm.gid,
1204                           shp->shm_perm.cuid,
1205                           shp->shm_perm.cgid,
1206                           shp->shm_atim,
1207                           shp->shm_dtim,
1208                           shp->shm_ctim,
1209                           rss * PAGE_SIZE,
1210                           swp * PAGE_SIZE);
1211 }
1212 #endif