Simplify semaphore implementation
[linux-2.6/mini2440.git] / ipc / shm.c
blobcc63fae02f064d298689279a46599a8159b01df1
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.
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>
16 * support for audit of ipc object properties and permission changes
17 * Dustin Kirkland <dustin.kirkland@us.ibm.com>
19 * namespaces support
20 * OpenVZ, SWsoft Inc.
21 * Pavel Emelianov <xemul@openvz.org>
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>
43 #include <asm/uaccess.h>
45 #include "util.h"
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;
54 #define shm_file_data(file) (*((struct shm_file_data **)&(file)->private_data))
56 static const struct file_operations shm_file_operations;
57 static struct vm_operations_struct shm_vm_ops;
59 #define shm_ids(ns) ((ns)->ids[IPC_SHM_IDS])
61 #define shm_unlock(shp) \
62 ipc_unlock(&(shp)->shm_perm)
63 #define shm_buildid(id, seq) ipc_buildid(id, seq)
65 static int newseg(struct ipc_namespace *, struct ipc_params *);
66 static void shm_open(struct vm_area_struct *vma);
67 static void shm_close(struct vm_area_struct *vma);
68 static void shm_destroy (struct ipc_namespace *ns, struct shmid_kernel *shp);
69 #ifdef CONFIG_PROC_FS
70 static int sysvipc_shm_proc_show(struct seq_file *s, void *it);
71 #endif
73 void shm_init_ns(struct ipc_namespace *ns)
75 ns->shm_ctlmax = SHMMAX;
76 ns->shm_ctlall = SHMALL;
77 ns->shm_ctlmni = SHMMNI;
78 ns->shm_tot = 0;
79 ipc_init_ids(&ns->ids[IPC_SHM_IDS]);
83 * Called with shm_ids.rw_mutex (writer) and the shp structure locked.
84 * Only shm_ids.rw_mutex remains locked on exit.
86 static void do_shm_rmid(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
88 struct shmid_kernel *shp;
89 shp = container_of(ipcp, struct shmid_kernel, shm_perm);
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);
100 #ifdef CONFIG_IPC_NS
101 void shm_exit_ns(struct ipc_namespace *ns)
103 free_ipcs(ns, &shm_ids(ns), do_shm_rmid);
105 #endif
107 void __init shm_init (void)
109 shm_init_ns(&init_ipc_ns);
110 ipc_init_proc_interface("sysvipc/shm",
111 " key shmid perms size cpid lpid nattch uid gid cuid cgid atime dtime ctime\n",
112 IPC_SHM_IDS, sysvipc_shm_proc_show);
116 * shm_lock_(check_)down routines are called in the paths where the rw_mutex
117 * is held to protect access to the idr tree.
119 static inline struct shmid_kernel *shm_lock_down(struct ipc_namespace *ns,
120 int id)
122 struct kern_ipc_perm *ipcp = ipc_lock_down(&shm_ids(ns), id);
124 if (IS_ERR(ipcp))
125 return (struct shmid_kernel *)ipcp;
127 return container_of(ipcp, struct shmid_kernel, shm_perm);
130 static inline struct shmid_kernel *shm_lock_check_down(
131 struct ipc_namespace *ns,
132 int id)
134 struct kern_ipc_perm *ipcp = ipc_lock_check_down(&shm_ids(ns), id);
136 if (IS_ERR(ipcp))
137 return (struct shmid_kernel *)ipcp;
139 return container_of(ipcp, struct shmid_kernel, shm_perm);
143 * shm_lock_(check_) routines are called in the paths where the rw_mutex
144 * is not held.
146 static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id)
148 struct kern_ipc_perm *ipcp = ipc_lock(&shm_ids(ns), id);
150 if (IS_ERR(ipcp))
151 return (struct shmid_kernel *)ipcp;
153 return container_of(ipcp, struct shmid_kernel, shm_perm);
156 static inline struct shmid_kernel *shm_lock_check(struct ipc_namespace *ns,
157 int id)
159 struct kern_ipc_perm *ipcp = ipc_lock_check(&shm_ids(ns), id);
161 if (IS_ERR(ipcp))
162 return (struct shmid_kernel *)ipcp;
164 return container_of(ipcp, struct shmid_kernel, shm_perm);
167 static inline void shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *s)
169 ipc_rmid(&shm_ids(ns), &s->shm_perm);
172 static inline int shm_addid(struct ipc_namespace *ns, struct shmid_kernel *shp)
174 return ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni);
179 /* This is called by fork, once for every shm attach. */
180 static void shm_open(struct vm_area_struct *vma)
182 struct file *file = vma->vm_file;
183 struct shm_file_data *sfd = shm_file_data(file);
184 struct shmid_kernel *shp;
186 shp = shm_lock(sfd->ns, sfd->id);
187 BUG_ON(IS_ERR(shp));
188 shp->shm_atim = get_seconds();
189 shp->shm_lprid = task_tgid_vnr(current);
190 shp->shm_nattch++;
191 shm_unlock(shp);
195 * shm_destroy - free the struct shmid_kernel
197 * @ns: namespace
198 * @shp: struct to free
200 * It has to be called with shp and shm_ids.rw_mutex (writer) locked,
201 * but returns with shp unlocked and freed.
203 static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
205 ns->shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT;
206 shm_rmid(ns, shp);
207 shm_unlock(shp);
208 if (!is_file_hugepages(shp->shm_file))
209 shmem_lock(shp->shm_file, 0, shp->mlock_user);
210 else
211 user_shm_unlock(shp->shm_file->f_path.dentry->d_inode->i_size,
212 shp->mlock_user);
213 fput (shp->shm_file);
214 security_shm_free(shp);
215 ipc_rcu_putref(shp);
219 * remove the attach descriptor vma.
220 * free memory for segment if it is marked destroyed.
221 * The descriptor has already been removed from the current->mm->mmap list
222 * and will later be kfree()d.
224 static void shm_close(struct vm_area_struct *vma)
226 struct file * file = vma->vm_file;
227 struct shm_file_data *sfd = shm_file_data(file);
228 struct shmid_kernel *shp;
229 struct ipc_namespace *ns = sfd->ns;
231 down_write(&shm_ids(ns).rw_mutex);
232 /* remove from the list of attaches of the shm segment */
233 shp = shm_lock_down(ns, sfd->id);
234 BUG_ON(IS_ERR(shp));
235 shp->shm_lprid = task_tgid_vnr(current);
236 shp->shm_dtim = get_seconds();
237 shp->shm_nattch--;
238 if(shp->shm_nattch == 0 &&
239 shp->shm_perm.mode & SHM_DEST)
240 shm_destroy(ns, shp);
241 else
242 shm_unlock(shp);
243 up_write(&shm_ids(ns).rw_mutex);
246 static int shm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
248 struct file *file = vma->vm_file;
249 struct shm_file_data *sfd = shm_file_data(file);
251 return sfd->vm_ops->fault(vma, vmf);
254 #ifdef CONFIG_NUMA
255 static int shm_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
257 struct file *file = vma->vm_file;
258 struct shm_file_data *sfd = shm_file_data(file);
259 int err = 0;
260 if (sfd->vm_ops->set_policy)
261 err = sfd->vm_ops->set_policy(vma, new);
262 return err;
265 static struct mempolicy *shm_get_policy(struct vm_area_struct *vma,
266 unsigned long addr)
268 struct file *file = vma->vm_file;
269 struct shm_file_data *sfd = shm_file_data(file);
270 struct mempolicy *pol = NULL;
272 if (sfd->vm_ops->get_policy)
273 pol = sfd->vm_ops->get_policy(vma, addr);
274 else if (vma->vm_policy) {
275 pol = vma->vm_policy;
276 mpol_get(pol); /* get_vma_policy() expects this */
277 } else
278 pol = current->mempolicy;
279 return pol;
281 #endif
283 static int shm_mmap(struct file * file, struct vm_area_struct * vma)
285 struct shm_file_data *sfd = shm_file_data(file);
286 int ret;
288 ret = sfd->file->f_op->mmap(sfd->file, vma);
289 if (ret != 0)
290 return ret;
291 sfd->vm_ops = vma->vm_ops;
292 #ifdef CONFIG_MMU
293 BUG_ON(!sfd->vm_ops->fault);
294 #endif
295 vma->vm_ops = &shm_vm_ops;
296 shm_open(vma);
298 return ret;
301 static int shm_release(struct inode *ino, struct file *file)
303 struct shm_file_data *sfd = shm_file_data(file);
305 put_ipc_ns(sfd->ns);
306 shm_file_data(file) = NULL;
307 kfree(sfd);
308 return 0;
311 static int shm_fsync(struct file *file, struct dentry *dentry, int datasync)
313 int (*fsync) (struct file *, struct dentry *, int datasync);
314 struct shm_file_data *sfd = shm_file_data(file);
315 int ret = -EINVAL;
317 fsync = sfd->file->f_op->fsync;
318 if (fsync)
319 ret = fsync(sfd->file, sfd->file->f_path.dentry, datasync);
320 return ret;
323 static unsigned long shm_get_unmapped_area(struct file *file,
324 unsigned long addr, unsigned long len, unsigned long pgoff,
325 unsigned long flags)
327 struct shm_file_data *sfd = shm_file_data(file);
328 return get_unmapped_area(sfd->file, addr, len, pgoff, flags);
331 int is_file_shm_hugepages(struct file *file)
333 int ret = 0;
335 if (file->f_op == &shm_file_operations) {
336 struct shm_file_data *sfd;
337 sfd = shm_file_data(file);
338 ret = is_file_hugepages(sfd->file);
340 return ret;
343 static const struct file_operations shm_file_operations = {
344 .mmap = shm_mmap,
345 .fsync = shm_fsync,
346 .release = shm_release,
347 .get_unmapped_area = shm_get_unmapped_area,
350 static struct vm_operations_struct shm_vm_ops = {
351 .open = shm_open, /* callback for a new vm-area open */
352 .close = shm_close, /* callback for when the vm-area is released */
353 .fault = shm_fault,
354 #if defined(CONFIG_NUMA)
355 .set_policy = shm_set_policy,
356 .get_policy = shm_get_policy,
357 #endif
361 * newseg - Create a new shared memory segment
362 * @ns: namespace
363 * @params: ptr to the structure that contains key, size and shmflg
365 * Called with shm_ids.rw_mutex held as a writer.
368 static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
370 key_t key = params->key;
371 int shmflg = params->flg;
372 size_t size = params->u.size;
373 int error;
374 struct shmid_kernel *shp;
375 int numpages = (size + PAGE_SIZE -1) >> PAGE_SHIFT;
376 struct file * file;
377 char name[13];
378 int id;
380 if (size < SHMMIN || size > ns->shm_ctlmax)
381 return -EINVAL;
383 if (ns->shm_tot + numpages > ns->shm_ctlall)
384 return -ENOSPC;
386 shp = ipc_rcu_alloc(sizeof(*shp));
387 if (!shp)
388 return -ENOMEM;
390 shp->shm_perm.key = key;
391 shp->shm_perm.mode = (shmflg & S_IRWXUGO);
392 shp->mlock_user = NULL;
394 shp->shm_perm.security = NULL;
395 error = security_shm_alloc(shp);
396 if (error) {
397 ipc_rcu_putref(shp);
398 return error;
401 sprintf (name, "SYSV%08x", key);
402 if (shmflg & SHM_HUGETLB) {
403 /* hugetlb_file_setup takes care of mlock user accounting */
404 file = hugetlb_file_setup(name, size);
405 shp->mlock_user = current->user;
406 } else {
407 int acctflag = VM_ACCOUNT;
409 * Do not allow no accounting for OVERCOMMIT_NEVER, even
410 * if it's asked for.
412 if ((shmflg & SHM_NORESERVE) &&
413 sysctl_overcommit_memory != OVERCOMMIT_NEVER)
414 acctflag = 0;
415 file = shmem_file_setup(name, size, acctflag);
417 error = PTR_ERR(file);
418 if (IS_ERR(file))
419 goto no_file;
421 id = shm_addid(ns, shp);
422 if (id < 0) {
423 error = id;
424 goto no_id;
427 shp->shm_cprid = task_tgid_vnr(current);
428 shp->shm_lprid = 0;
429 shp->shm_atim = shp->shm_dtim = 0;
430 shp->shm_ctim = get_seconds();
431 shp->shm_segsz = size;
432 shp->shm_nattch = 0;
433 shp->shm_perm.id = shm_buildid(id, shp->shm_perm.seq);
434 shp->shm_file = file;
436 * shmid gets reported as "inode#" in /proc/pid/maps.
437 * proc-ps tools use this. Changing this will break them.
439 file->f_dentry->d_inode->i_ino = shp->shm_perm.id;
441 ns->shm_tot += numpages;
442 error = shp->shm_perm.id;
443 shm_unlock(shp);
444 return error;
446 no_id:
447 fput(file);
448 no_file:
449 security_shm_free(shp);
450 ipc_rcu_putref(shp);
451 return error;
455 * Called with shm_ids.rw_mutex and ipcp locked.
457 static inline int shm_security(struct kern_ipc_perm *ipcp, int shmflg)
459 struct shmid_kernel *shp;
461 shp = container_of(ipcp, struct shmid_kernel, shm_perm);
462 return security_shm_associate(shp, shmflg);
466 * Called with shm_ids.rw_mutex and ipcp locked.
468 static inline int shm_more_checks(struct kern_ipc_perm *ipcp,
469 struct ipc_params *params)
471 struct shmid_kernel *shp;
473 shp = container_of(ipcp, struct shmid_kernel, shm_perm);
474 if (shp->shm_segsz < params->u.size)
475 return -EINVAL;
477 return 0;
480 asmlinkage long sys_shmget (key_t key, size_t size, int shmflg)
482 struct ipc_namespace *ns;
483 struct ipc_ops shm_ops;
484 struct ipc_params shm_params;
486 ns = current->nsproxy->ipc_ns;
488 shm_ops.getnew = newseg;
489 shm_ops.associate = shm_security;
490 shm_ops.more_checks = shm_more_checks;
492 shm_params.key = key;
493 shm_params.flg = shmflg;
494 shm_params.u.size = size;
496 return ipcget(ns, &shm_ids(ns), &shm_ops, &shm_params);
499 static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version)
501 switch(version) {
502 case IPC_64:
503 return copy_to_user(buf, in, sizeof(*in));
504 case IPC_OLD:
506 struct shmid_ds out;
508 ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
509 out.shm_segsz = in->shm_segsz;
510 out.shm_atime = in->shm_atime;
511 out.shm_dtime = in->shm_dtime;
512 out.shm_ctime = in->shm_ctime;
513 out.shm_cpid = in->shm_cpid;
514 out.shm_lpid = in->shm_lpid;
515 out.shm_nattch = in->shm_nattch;
517 return copy_to_user(buf, &out, sizeof(out));
519 default:
520 return -EINVAL;
524 struct shm_setbuf {
525 uid_t uid;
526 gid_t gid;
527 mode_t mode;
530 static inline unsigned long copy_shmid_from_user(struct shm_setbuf *out, void __user *buf, int version)
532 switch(version) {
533 case IPC_64:
535 struct shmid64_ds tbuf;
537 if (copy_from_user(&tbuf, buf, sizeof(tbuf)))
538 return -EFAULT;
540 out->uid = tbuf.shm_perm.uid;
541 out->gid = tbuf.shm_perm.gid;
542 out->mode = tbuf.shm_perm.mode;
544 return 0;
546 case IPC_OLD:
548 struct shmid_ds tbuf_old;
550 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
551 return -EFAULT;
553 out->uid = tbuf_old.shm_perm.uid;
554 out->gid = tbuf_old.shm_perm.gid;
555 out->mode = tbuf_old.shm_perm.mode;
557 return 0;
559 default:
560 return -EINVAL;
564 static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminfo64 *in, int version)
566 switch(version) {
567 case IPC_64:
568 return copy_to_user(buf, in, sizeof(*in));
569 case IPC_OLD:
571 struct shminfo out;
573 if(in->shmmax > INT_MAX)
574 out.shmmax = INT_MAX;
575 else
576 out.shmmax = (int)in->shmmax;
578 out.shmmin = in->shmmin;
579 out.shmmni = in->shmmni;
580 out.shmseg = in->shmseg;
581 out.shmall = in->shmall;
583 return copy_to_user(buf, &out, sizeof(out));
585 default:
586 return -EINVAL;
591 * Called with shm_ids.rw_mutex held as a reader
593 static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
594 unsigned long *swp)
596 int next_id;
597 int total, in_use;
599 *rss = 0;
600 *swp = 0;
602 in_use = shm_ids(ns).in_use;
604 for (total = 0, next_id = 0; total < in_use; next_id++) {
605 struct shmid_kernel *shp;
606 struct inode *inode;
608 shp = idr_find(&shm_ids(ns).ipcs_idr, next_id);
609 if (shp == NULL)
610 continue;
612 inode = shp->shm_file->f_path.dentry->d_inode;
614 if (is_file_hugepages(shp->shm_file)) {
615 struct address_space *mapping = inode->i_mapping;
616 *rss += (HPAGE_SIZE/PAGE_SIZE)*mapping->nrpages;
617 } else {
618 struct shmem_inode_info *info = SHMEM_I(inode);
619 spin_lock(&info->lock);
620 *rss += inode->i_mapping->nrpages;
621 *swp += info->swapped;
622 spin_unlock(&info->lock);
625 total++;
629 asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds __user *buf)
631 struct shm_setbuf setbuf;
632 struct shmid_kernel *shp;
633 int err, version;
634 struct ipc_namespace *ns;
636 if (cmd < 0 || shmid < 0) {
637 err = -EINVAL;
638 goto out;
641 version = ipc_parse_version(&cmd);
642 ns = current->nsproxy->ipc_ns;
644 switch (cmd) { /* replace with proc interface ? */
645 case IPC_INFO:
647 struct shminfo64 shminfo;
649 err = security_shm_shmctl(NULL, cmd);
650 if (err)
651 return err;
653 memset(&shminfo,0,sizeof(shminfo));
654 shminfo.shmmni = shminfo.shmseg = ns->shm_ctlmni;
655 shminfo.shmmax = ns->shm_ctlmax;
656 shminfo.shmall = ns->shm_ctlall;
658 shminfo.shmmin = SHMMIN;
659 if(copy_shminfo_to_user (buf, &shminfo, version))
660 return -EFAULT;
662 down_read(&shm_ids(ns).rw_mutex);
663 err = ipc_get_maxid(&shm_ids(ns));
664 up_read(&shm_ids(ns).rw_mutex);
666 if(err<0)
667 err = 0;
668 goto out;
670 case SHM_INFO:
672 struct shm_info shm_info;
674 err = security_shm_shmctl(NULL, cmd);
675 if (err)
676 return err;
678 memset(&shm_info,0,sizeof(shm_info));
679 down_read(&shm_ids(ns).rw_mutex);
680 shm_info.used_ids = shm_ids(ns).in_use;
681 shm_get_stat (ns, &shm_info.shm_rss, &shm_info.shm_swp);
682 shm_info.shm_tot = ns->shm_tot;
683 shm_info.swap_attempts = 0;
684 shm_info.swap_successes = 0;
685 err = ipc_get_maxid(&shm_ids(ns));
686 up_read(&shm_ids(ns).rw_mutex);
687 if(copy_to_user (buf, &shm_info, sizeof(shm_info))) {
688 err = -EFAULT;
689 goto out;
692 err = err < 0 ? 0 : err;
693 goto out;
695 case SHM_STAT:
696 case IPC_STAT:
698 struct shmid64_ds tbuf;
699 int result;
701 if (!buf) {
702 err = -EFAULT;
703 goto out;
706 if (cmd == SHM_STAT) {
707 shp = shm_lock(ns, shmid);
708 if (IS_ERR(shp)) {
709 err = PTR_ERR(shp);
710 goto out;
712 result = shp->shm_perm.id;
713 } else {
714 shp = shm_lock_check(ns, shmid);
715 if (IS_ERR(shp)) {
716 err = PTR_ERR(shp);
717 goto out;
719 result = 0;
721 err=-EACCES;
722 if (ipcperms (&shp->shm_perm, S_IRUGO))
723 goto out_unlock;
724 err = security_shm_shmctl(shp, cmd);
725 if (err)
726 goto out_unlock;
727 memset(&tbuf, 0, sizeof(tbuf));
728 kernel_to_ipc64_perm(&shp->shm_perm, &tbuf.shm_perm);
729 tbuf.shm_segsz = shp->shm_segsz;
730 tbuf.shm_atime = shp->shm_atim;
731 tbuf.shm_dtime = shp->shm_dtim;
732 tbuf.shm_ctime = shp->shm_ctim;
733 tbuf.shm_cpid = shp->shm_cprid;
734 tbuf.shm_lpid = shp->shm_lprid;
735 tbuf.shm_nattch = shp->shm_nattch;
736 shm_unlock(shp);
737 if(copy_shmid_to_user (buf, &tbuf, version))
738 err = -EFAULT;
739 else
740 err = result;
741 goto out;
743 case SHM_LOCK:
744 case SHM_UNLOCK:
746 shp = shm_lock_check(ns, shmid);
747 if (IS_ERR(shp)) {
748 err = PTR_ERR(shp);
749 goto out;
752 err = audit_ipc_obj(&(shp->shm_perm));
753 if (err)
754 goto out_unlock;
756 if (!capable(CAP_IPC_LOCK)) {
757 err = -EPERM;
758 if (current->euid != shp->shm_perm.uid &&
759 current->euid != shp->shm_perm.cuid)
760 goto out_unlock;
761 if (cmd == SHM_LOCK &&
762 !current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur)
763 goto out_unlock;
766 err = security_shm_shmctl(shp, cmd);
767 if (err)
768 goto out_unlock;
770 if(cmd==SHM_LOCK) {
771 struct user_struct * user = current->user;
772 if (!is_file_hugepages(shp->shm_file)) {
773 err = shmem_lock(shp->shm_file, 1, user);
774 if (!err && !(shp->shm_perm.mode & SHM_LOCKED)){
775 shp->shm_perm.mode |= SHM_LOCKED;
776 shp->mlock_user = user;
779 } else if (!is_file_hugepages(shp->shm_file)) {
780 shmem_lock(shp->shm_file, 0, shp->mlock_user);
781 shp->shm_perm.mode &= ~SHM_LOCKED;
782 shp->mlock_user = NULL;
784 shm_unlock(shp);
785 goto out;
787 case IPC_RMID:
790 * We cannot simply remove the file. The SVID states
791 * that the block remains until the last person
792 * detaches from it, then is deleted. A shmat() on
793 * an RMID segment is legal in older Linux and if
794 * we change it apps break...
796 * Instead we set a destroyed flag, and then blow
797 * the name away when the usage hits zero.
799 down_write(&shm_ids(ns).rw_mutex);
800 shp = shm_lock_check_down(ns, shmid);
801 if (IS_ERR(shp)) {
802 err = PTR_ERR(shp);
803 goto out_up;
806 err = audit_ipc_obj(&(shp->shm_perm));
807 if (err)
808 goto out_unlock_up;
810 if (current->euid != shp->shm_perm.uid &&
811 current->euid != shp->shm_perm.cuid &&
812 !capable(CAP_SYS_ADMIN)) {
813 err=-EPERM;
814 goto out_unlock_up;
817 err = security_shm_shmctl(shp, cmd);
818 if (err)
819 goto out_unlock_up;
821 do_shm_rmid(ns, &shp->shm_perm);
822 up_write(&shm_ids(ns).rw_mutex);
823 goto out;
826 case IPC_SET:
828 if (!buf) {
829 err = -EFAULT;
830 goto out;
833 if (copy_shmid_from_user (&setbuf, buf, version)) {
834 err = -EFAULT;
835 goto out;
837 down_write(&shm_ids(ns).rw_mutex);
838 shp = shm_lock_check_down(ns, shmid);
839 if (IS_ERR(shp)) {
840 err = PTR_ERR(shp);
841 goto out_up;
843 err = audit_ipc_obj(&(shp->shm_perm));
844 if (err)
845 goto out_unlock_up;
846 err = audit_ipc_set_perm(0, setbuf.uid, setbuf.gid, setbuf.mode);
847 if (err)
848 goto out_unlock_up;
849 err=-EPERM;
850 if (current->euid != shp->shm_perm.uid &&
851 current->euid != shp->shm_perm.cuid &&
852 !capable(CAP_SYS_ADMIN)) {
853 goto out_unlock_up;
856 err = security_shm_shmctl(shp, cmd);
857 if (err)
858 goto out_unlock_up;
860 shp->shm_perm.uid = setbuf.uid;
861 shp->shm_perm.gid = setbuf.gid;
862 shp->shm_perm.mode = (shp->shm_perm.mode & ~S_IRWXUGO)
863 | (setbuf.mode & S_IRWXUGO);
864 shp->shm_ctim = get_seconds();
865 break;
868 default:
869 err = -EINVAL;
870 goto out;
873 err = 0;
874 out_unlock_up:
875 shm_unlock(shp);
876 out_up:
877 up_write(&shm_ids(ns).rw_mutex);
878 goto out;
879 out_unlock:
880 shm_unlock(shp);
881 out:
882 return err;
886 * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
888 * NOTE! Despite the name, this is NOT a direct system call entrypoint. The
889 * "raddr" thing points to kernel space, and there has to be a wrapper around
890 * this.
892 long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr)
894 struct shmid_kernel *shp;
895 unsigned long addr;
896 unsigned long size;
897 struct file * file;
898 int err;
899 unsigned long flags;
900 unsigned long prot;
901 int acc_mode;
902 unsigned long user_addr;
903 struct ipc_namespace *ns;
904 struct shm_file_data *sfd;
905 struct path path;
906 mode_t f_mode;
908 err = -EINVAL;
909 if (shmid < 0)
910 goto out;
911 else if ((addr = (ulong)shmaddr)) {
912 if (addr & (SHMLBA-1)) {
913 if (shmflg & SHM_RND)
914 addr &= ~(SHMLBA-1); /* round down */
915 else
916 #ifndef __ARCH_FORCE_SHMLBA
917 if (addr & ~PAGE_MASK)
918 #endif
919 goto out;
921 flags = MAP_SHARED | MAP_FIXED;
922 } else {
923 if ((shmflg & SHM_REMAP))
924 goto out;
926 flags = MAP_SHARED;
929 if (shmflg & SHM_RDONLY) {
930 prot = PROT_READ;
931 acc_mode = S_IRUGO;
932 f_mode = FMODE_READ;
933 } else {
934 prot = PROT_READ | PROT_WRITE;
935 acc_mode = S_IRUGO | S_IWUGO;
936 f_mode = FMODE_READ | FMODE_WRITE;
938 if (shmflg & SHM_EXEC) {
939 prot |= PROT_EXEC;
940 acc_mode |= S_IXUGO;
944 * We cannot rely on the fs check since SYSV IPC does have an
945 * additional creator id...
947 ns = current->nsproxy->ipc_ns;
948 shp = shm_lock_check(ns, shmid);
949 if (IS_ERR(shp)) {
950 err = PTR_ERR(shp);
951 goto out;
954 err = -EACCES;
955 if (ipcperms(&shp->shm_perm, acc_mode))
956 goto out_unlock;
958 err = security_shm_shmat(shp, shmaddr, shmflg);
959 if (err)
960 goto out_unlock;
962 path.dentry = dget(shp->shm_file->f_path.dentry);
963 path.mnt = shp->shm_file->f_path.mnt;
964 shp->shm_nattch++;
965 size = i_size_read(path.dentry->d_inode);
966 shm_unlock(shp);
968 err = -ENOMEM;
969 sfd = kzalloc(sizeof(*sfd), GFP_KERNEL);
970 if (!sfd)
971 goto out_put_dentry;
973 err = -ENOMEM;
975 file = alloc_file(path.mnt, path.dentry, f_mode, &shm_file_operations);
976 if (!file)
977 goto out_free;
979 file->private_data = sfd;
980 file->f_mapping = shp->shm_file->f_mapping;
981 sfd->id = shp->shm_perm.id;
982 sfd->ns = get_ipc_ns(ns);
983 sfd->file = shp->shm_file;
984 sfd->vm_ops = NULL;
986 down_write(&current->mm->mmap_sem);
987 if (addr && !(shmflg & SHM_REMAP)) {
988 err = -EINVAL;
989 if (find_vma_intersection(current->mm, addr, addr + size))
990 goto invalid;
992 * If shm segment goes below stack, make sure there is some
993 * space left for the stack to grow (at least 4 pages).
995 if (addr < current->mm->start_stack &&
996 addr > current->mm->start_stack - size - PAGE_SIZE * 5)
997 goto invalid;
1000 user_addr = do_mmap (file, addr, size, prot, flags, 0);
1001 *raddr = user_addr;
1002 err = 0;
1003 if (IS_ERR_VALUE(user_addr))
1004 err = (long)user_addr;
1005 invalid:
1006 up_write(&current->mm->mmap_sem);
1008 fput(file);
1010 out_nattch:
1011 down_write(&shm_ids(ns).rw_mutex);
1012 shp = shm_lock_down(ns, shmid);
1013 BUG_ON(IS_ERR(shp));
1014 shp->shm_nattch--;
1015 if(shp->shm_nattch == 0 &&
1016 shp->shm_perm.mode & SHM_DEST)
1017 shm_destroy(ns, shp);
1018 else
1019 shm_unlock(shp);
1020 up_write(&shm_ids(ns).rw_mutex);
1022 out:
1023 return err;
1025 out_unlock:
1026 shm_unlock(shp);
1027 goto out;
1029 out_free:
1030 kfree(sfd);
1031 out_put_dentry:
1032 dput(path.dentry);
1033 goto out_nattch;
1036 asmlinkage long sys_shmat(int shmid, char __user *shmaddr, int shmflg)
1038 unsigned long ret;
1039 long err;
1041 err = do_shmat(shmid, shmaddr, shmflg, &ret);
1042 if (err)
1043 return err;
1044 force_successful_syscall_return();
1045 return (long)ret;
1049 * detach and kill segment if marked destroyed.
1050 * The work is done in shm_close.
1052 asmlinkage long sys_shmdt(char __user *shmaddr)
1054 struct mm_struct *mm = current->mm;
1055 struct vm_area_struct *vma, *next;
1056 unsigned long addr = (unsigned long)shmaddr;
1057 loff_t size = 0;
1058 int retval = -EINVAL;
1060 if (addr & ~PAGE_MASK)
1061 return retval;
1063 down_write(&mm->mmap_sem);
1066 * This function tries to be smart and unmap shm segments that
1067 * were modified by partial mlock or munmap calls:
1068 * - It first determines the size of the shm segment that should be
1069 * unmapped: It searches for a vma that is backed by shm and that
1070 * started at address shmaddr. It records it's size and then unmaps
1071 * it.
1072 * - Then it unmaps all shm vmas that started at shmaddr and that
1073 * are within the initially determined size.
1074 * Errors from do_munmap are ignored: the function only fails if
1075 * it's called with invalid parameters or if it's called to unmap
1076 * a part of a vma. Both calls in this function are for full vmas,
1077 * the parameters are directly copied from the vma itself and always
1078 * valid - therefore do_munmap cannot fail. (famous last words?)
1081 * If it had been mremap()'d, the starting address would not
1082 * match the usual checks anyway. So assume all vma's are
1083 * above the starting address given.
1085 vma = find_vma(mm, addr);
1087 while (vma) {
1088 next = vma->vm_next;
1091 * Check if the starting address would match, i.e. it's
1092 * a fragment created by mprotect() and/or munmap(), or it
1093 * otherwise it starts at this address with no hassles.
1095 if ((vma->vm_ops == &shm_vm_ops) &&
1096 (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) {
1099 size = vma->vm_file->f_path.dentry->d_inode->i_size;
1100 do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
1102 * We discovered the size of the shm segment, so
1103 * break out of here and fall through to the next
1104 * loop that uses the size information to stop
1105 * searching for matching vma's.
1107 retval = 0;
1108 vma = next;
1109 break;
1111 vma = next;
1115 * We need look no further than the maximum address a fragment
1116 * could possibly have landed at. Also cast things to loff_t to
1117 * prevent overflows and make comparisions vs. equal-width types.
1119 size = PAGE_ALIGN(size);
1120 while (vma && (loff_t)(vma->vm_end - addr) <= size) {
1121 next = vma->vm_next;
1123 /* finding a matching vma now does not alter retval */
1124 if ((vma->vm_ops == &shm_vm_ops) &&
1125 (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff)
1127 do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
1128 vma = next;
1131 up_write(&mm->mmap_sem);
1132 return retval;
1135 #ifdef CONFIG_PROC_FS
1136 static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
1138 struct shmid_kernel *shp = it;
1139 char *format;
1141 #define SMALL_STRING "%10d %10d %4o %10u %5u %5u %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
1142 #define BIG_STRING "%10d %10d %4o %21u %5u %5u %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
1144 if (sizeof(size_t) <= sizeof(int))
1145 format = SMALL_STRING;
1146 else
1147 format = BIG_STRING;
1148 return seq_printf(s, format,
1149 shp->shm_perm.key,
1150 shp->shm_perm.id,
1151 shp->shm_perm.mode,
1152 shp->shm_segsz,
1153 shp->shm_cprid,
1154 shp->shm_lprid,
1155 shp->shm_nattch,
1156 shp->shm_perm.uid,
1157 shp->shm_perm.gid,
1158 shp->shm_perm.cuid,
1159 shp->shm_perm.cgid,
1160 shp->shm_atim,
1161 shp->shm_dtim,
1162 shp->shm_ctim);
1164 #endif