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>
21 * Pavel Emelianov <xemul@openvz.org>
24 #include <linux/slab.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>
47 struct shm_file_data {
49 struct ipc_namespace *ns;
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 const 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)
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);
69 static int sysvipc_shm_proc_show(struct seq_file *s, void *it);
72 void shm_init_ns(struct ipc_namespace *ns)
74 ns->shm_ctlmax = SHMMAX;
75 ns->shm_ctlall = SHMALL;
76 ns->shm_ctlmni = SHMMNI;
77 ns->shm_rmid_forced = 0;
79 ipc_init_ids(&shm_ids(ns));
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);
92 shp->shm_perm.mode |= SHM_DEST;
93 /* Do not find it any more */
94 shp->shm_perm.key = IPC_PRIVATE;
101 void shm_exit_ns(struct ipc_namespace *ns)
103 free_ipcs(ns, &shm_ids(ns), do_shm_rmid);
104 idr_destroy(&ns->ids[IPC_SHM_IDS].ipcs_idr);
108 void __init shm_init (void)
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",
115 " key shmid perms size cpid lpid nattch uid gid cuid cgid atime dtime ctime rss swap\n",
117 IPC_SHM_IDS, sysvipc_shm_proc_show);
121 * shm_lock_(check_) routines are called in the paths where the rw_mutex
122 * is not necessarily held.
124 static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id)
126 struct kern_ipc_perm *ipcp = ipc_lock(&shm_ids(ns), id);
129 return (struct shmid_kernel *)ipcp;
131 return container_of(ipcp, struct shmid_kernel, shm_perm);
134 static inline void shm_lock_by_ptr(struct shmid_kernel *ipcp)
137 spin_lock(&ipcp->shm_perm.lock);
140 static inline struct shmid_kernel *shm_lock_check(struct ipc_namespace *ns,
143 struct kern_ipc_perm *ipcp = ipc_lock_check(&shm_ids(ns), id);
146 return (struct shmid_kernel *)ipcp;
148 return container_of(ipcp, struct shmid_kernel, shm_perm);
151 static inline void shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *s)
153 ipc_rmid(&shm_ids(ns), &s->shm_perm);
157 /* This is called by fork, once for every shm attach. */
158 static void shm_open(struct vm_area_struct *vma)
160 struct file *file = vma->vm_file;
161 struct shm_file_data *sfd = shm_file_data(file);
162 struct shmid_kernel *shp;
164 shp = shm_lock(sfd->ns, sfd->id);
166 shp->shm_atim = get_seconds();
167 shp->shm_lprid = task_tgid_vnr(current);
173 * shm_destroy - free the struct shmid_kernel
176 * @shp: struct to free
178 * It has to be called with shp and shm_ids.rw_mutex (writer) locked,
179 * but returns with shp unlocked and freed.
181 static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
183 ns->shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT;
186 if (!is_file_hugepages(shp->shm_file))
187 shmem_lock(shp->shm_file, 0, shp->mlock_user);
188 else if (shp->mlock_user)
189 user_shm_unlock(shp->shm_file->f_path.dentry->d_inode->i_size,
191 fput (shp->shm_file);
192 security_shm_free(shp);
197 * shm_may_destroy - identifies whether shm segment should be destroyed now
199 * Returns true if and only if there are no active users of the segment and
200 * one of the following is true:
202 * 1) shmctl(id, IPC_RMID, NULL) was called for this shp
204 * 2) sysctl kernel.shm_rmid_forced is set to 1.
206 static bool shm_may_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
208 return (shp->shm_nattch == 0) &&
209 (ns->shm_rmid_forced ||
210 (shp->shm_perm.mode & SHM_DEST));
214 * remove the attach descriptor vma.
215 * free memory for segment if it is marked destroyed.
216 * The descriptor has already been removed from the current->mm->mmap list
217 * and will later be kfree()d.
219 static void shm_close(struct vm_area_struct *vma)
221 struct file * file = vma->vm_file;
222 struct shm_file_data *sfd = shm_file_data(file);
223 struct shmid_kernel *shp;
224 struct ipc_namespace *ns = sfd->ns;
226 down_write(&shm_ids(ns).rw_mutex);
227 /* remove from the list of attaches of the shm segment */
228 shp = shm_lock(ns, sfd->id);
230 shp->shm_lprid = task_tgid_vnr(current);
231 shp->shm_dtim = get_seconds();
233 if (shm_may_destroy(ns, shp))
234 shm_destroy(ns, shp);
237 up_write(&shm_ids(ns).rw_mutex);
240 /* Called with ns->shm_ids(ns).rw_mutex locked */
241 static int shm_try_destroy_current(int id, void *p, void *data)
243 struct ipc_namespace *ns = data;
244 struct kern_ipc_perm *ipcp = p;
245 struct shmid_kernel *shp = container_of(ipcp, struct shmid_kernel, shm_perm);
247 if (shp->shm_creator != current)
251 * Mark it as orphaned to destroy the segment when
252 * kernel.shm_rmid_forced is changed.
253 * It is noop if the following shm_may_destroy() returns true.
255 shp->shm_creator = NULL;
258 * Don't even try to destroy it. If shm_rmid_forced=0 and IPC_RMID
259 * is not set, it shouldn't be deleted here.
261 if (!ns->shm_rmid_forced)
264 if (shm_may_destroy(ns, shp)) {
265 shm_lock_by_ptr(shp);
266 shm_destroy(ns, shp);
271 /* Called with ns->shm_ids(ns).rw_mutex locked */
272 static int shm_try_destroy_orphaned(int id, void *p, void *data)
274 struct ipc_namespace *ns = data;
275 struct kern_ipc_perm *ipcp = p;
276 struct shmid_kernel *shp = container_of(ipcp, struct shmid_kernel, shm_perm);
279 * We want to destroy segments without users and with already
280 * exit'ed originating process.
282 * As shp->* are changed under rw_mutex, it's safe to skip shp locking.
284 if (shp->shm_creator != NULL)
287 if (shm_may_destroy(ns, shp)) {
288 shm_lock_by_ptr(shp);
289 shm_destroy(ns, shp);
294 void shm_destroy_orphaned(struct ipc_namespace *ns)
296 down_write(&shm_ids(ns).rw_mutex);
297 if (&shm_ids(ns).in_use)
298 idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_orphaned, ns);
299 up_write(&shm_ids(ns).rw_mutex);
303 void exit_shm(struct task_struct *task)
305 struct ipc_namespace *ns = task->nsproxy->ipc_ns;
307 /* Destroy all already created segments, but not mapped yet */
308 down_write(&shm_ids(ns).rw_mutex);
309 if (&shm_ids(ns).in_use)
310 idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_current, ns);
311 up_write(&shm_ids(ns).rw_mutex);
314 static int shm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
316 struct file *file = vma->vm_file;
317 struct shm_file_data *sfd = shm_file_data(file);
319 return sfd->vm_ops->fault(vma, vmf);
323 static int shm_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
325 struct file *file = vma->vm_file;
326 struct shm_file_data *sfd = shm_file_data(file);
328 if (sfd->vm_ops->set_policy)
329 err = sfd->vm_ops->set_policy(vma, new);
333 static struct mempolicy *shm_get_policy(struct vm_area_struct *vma,
336 struct file *file = vma->vm_file;
337 struct shm_file_data *sfd = shm_file_data(file);
338 struct mempolicy *pol = NULL;
340 if (sfd->vm_ops->get_policy)
341 pol = sfd->vm_ops->get_policy(vma, addr);
342 else if (vma->vm_policy)
343 pol = vma->vm_policy;
349 static int shm_mmap(struct file * file, struct vm_area_struct * vma)
351 struct shm_file_data *sfd = shm_file_data(file);
354 ret = sfd->file->f_op->mmap(sfd->file, vma);
357 sfd->vm_ops = vma->vm_ops;
359 BUG_ON(!sfd->vm_ops->fault);
361 vma->vm_ops = &shm_vm_ops;
367 static int shm_release(struct inode *ino, struct file *file)
369 struct shm_file_data *sfd = shm_file_data(file);
372 shm_file_data(file) = NULL;
377 static int shm_fsync(struct file *file, loff_t start, loff_t end, int datasync)
379 struct shm_file_data *sfd = shm_file_data(file);
381 if (!sfd->file->f_op->fsync)
383 return sfd->file->f_op->fsync(sfd->file, start, end, datasync);
386 static unsigned long shm_get_unmapped_area(struct file *file,
387 unsigned long addr, unsigned long len, unsigned long pgoff,
390 struct shm_file_data *sfd = shm_file_data(file);
391 return sfd->file->f_op->get_unmapped_area(sfd->file, addr, len,
395 static const struct file_operations shm_file_operations = {
398 .release = shm_release,
400 .get_unmapped_area = shm_get_unmapped_area,
402 .llseek = noop_llseek,
405 static const struct file_operations shm_file_operations_huge = {
408 .release = shm_release,
409 .get_unmapped_area = shm_get_unmapped_area,
410 .llseek = noop_llseek,
413 int is_file_shm_hugepages(struct file *file)
415 return file->f_op == &shm_file_operations_huge;
418 static const struct vm_operations_struct shm_vm_ops = {
419 .open = shm_open, /* callback for a new vm-area open */
420 .close = shm_close, /* callback for when the vm-area is released */
422 #if defined(CONFIG_NUMA)
423 .set_policy = shm_set_policy,
424 .get_policy = shm_get_policy,
429 * newseg - Create a new shared memory segment
431 * @params: ptr to the structure that contains key, size and shmflg
433 * Called with shm_ids.rw_mutex held as a writer.
436 static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
438 key_t key = params->key;
439 int shmflg = params->flg;
440 size_t size = params->u.size;
442 struct shmid_kernel *shp;
443 int numpages = (size + PAGE_SIZE -1) >> PAGE_SHIFT;
447 vm_flags_t acctflag = 0;
449 if (size < SHMMIN || size > ns->shm_ctlmax)
452 if (ns->shm_tot + numpages > ns->shm_ctlall)
455 shp = ipc_rcu_alloc(sizeof(*shp));
459 shp->shm_perm.key = key;
460 shp->shm_perm.mode = (shmflg & S_IRWXUGO);
461 shp->mlock_user = NULL;
463 shp->shm_perm.security = NULL;
464 error = security_shm_alloc(shp);
470 sprintf (name, "SYSV%08x", key);
471 if (shmflg & SHM_HUGETLB) {
472 /* hugetlb_file_setup applies strict accounting */
473 if (shmflg & SHM_NORESERVE)
474 acctflag = VM_NORESERVE;
475 file = hugetlb_file_setup(name, size, acctflag,
476 &shp->mlock_user, HUGETLB_SHMFS_INODE);
479 * Do not allow no accounting for OVERCOMMIT_NEVER, even
482 if ((shmflg & SHM_NORESERVE) &&
483 sysctl_overcommit_memory != OVERCOMMIT_NEVER)
484 acctflag = VM_NORESERVE;
485 file = shmem_file_setup(name, size, acctflag);
487 error = PTR_ERR(file);
491 id = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni);
497 shp->shm_cprid = task_tgid_vnr(current);
499 shp->shm_atim = shp->shm_dtim = 0;
500 shp->shm_ctim = get_seconds();
501 shp->shm_segsz = size;
503 shp->shm_file = file;
504 shp->shm_creator = current;
506 * shmid gets reported as "inode#" in /proc/pid/maps.
507 * proc-ps tools use this. Changing this will break them.
509 file->f_dentry->d_inode->i_ino = shp->shm_perm.id;
511 ns->shm_tot += numpages;
512 error = shp->shm_perm.id;
517 if (is_file_hugepages(file) && shp->mlock_user)
518 user_shm_unlock(size, shp->mlock_user);
521 security_shm_free(shp);
527 * Called with shm_ids.rw_mutex and ipcp locked.
529 static inline int shm_security(struct kern_ipc_perm *ipcp, int shmflg)
531 struct shmid_kernel *shp;
533 shp = container_of(ipcp, struct shmid_kernel, shm_perm);
534 return security_shm_associate(shp, shmflg);
538 * Called with shm_ids.rw_mutex and ipcp locked.
540 static inline int shm_more_checks(struct kern_ipc_perm *ipcp,
541 struct ipc_params *params)
543 struct shmid_kernel *shp;
545 shp = container_of(ipcp, struct shmid_kernel, shm_perm);
546 if (shp->shm_segsz < params->u.size)
552 SYSCALL_DEFINE3(shmget, key_t, key, size_t, size, int, shmflg)
554 struct ipc_namespace *ns;
555 struct ipc_ops shm_ops;
556 struct ipc_params shm_params;
558 ns = current->nsproxy->ipc_ns;
560 shm_ops.getnew = newseg;
561 shm_ops.associate = shm_security;
562 shm_ops.more_checks = shm_more_checks;
564 shm_params.key = key;
565 shm_params.flg = shmflg;
566 shm_params.u.size = size;
568 return ipcget(ns, &shm_ids(ns), &shm_ops, &shm_params);
571 static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version)
575 return copy_to_user(buf, in, sizeof(*in));
580 memset(&out, 0, sizeof(out));
581 ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
582 out.shm_segsz = in->shm_segsz;
583 out.shm_atime = in->shm_atime;
584 out.shm_dtime = in->shm_dtime;
585 out.shm_ctime = in->shm_ctime;
586 out.shm_cpid = in->shm_cpid;
587 out.shm_lpid = in->shm_lpid;
588 out.shm_nattch = in->shm_nattch;
590 return copy_to_user(buf, &out, sizeof(out));
597 static inline unsigned long
598 copy_shmid_from_user(struct shmid64_ds *out, void __user *buf, int version)
602 if (copy_from_user(out, buf, sizeof(*out)))
607 struct shmid_ds tbuf_old;
609 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
612 out->shm_perm.uid = tbuf_old.shm_perm.uid;
613 out->shm_perm.gid = tbuf_old.shm_perm.gid;
614 out->shm_perm.mode = tbuf_old.shm_perm.mode;
623 static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminfo64 *in, int version)
627 return copy_to_user(buf, in, sizeof(*in));
632 if(in->shmmax > INT_MAX)
633 out.shmmax = INT_MAX;
635 out.shmmax = (int)in->shmmax;
637 out.shmmin = in->shmmin;
638 out.shmmni = in->shmmni;
639 out.shmseg = in->shmseg;
640 out.shmall = in->shmall;
642 return copy_to_user(buf, &out, sizeof(out));
650 * Calculate and add used RSS and swap pages of a shm.
651 * Called with shm_ids.rw_mutex held as a reader
653 static void shm_add_rss_swap(struct shmid_kernel *shp,
654 unsigned long *rss_add, unsigned long *swp_add)
658 inode = shp->shm_file->f_path.dentry->d_inode;
660 if (is_file_hugepages(shp->shm_file)) {
661 struct address_space *mapping = inode->i_mapping;
662 struct hstate *h = hstate_file(shp->shm_file);
663 *rss_add += pages_per_huge_page(h) * mapping->nrpages;
666 struct shmem_inode_info *info = SHMEM_I(inode);
667 spin_lock(&info->lock);
668 *rss_add += inode->i_mapping->nrpages;
669 *swp_add += info->swapped;
670 spin_unlock(&info->lock);
672 *rss_add += inode->i_mapping->nrpages;
678 * Called with shm_ids.rw_mutex held as a reader
680 static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
689 in_use = shm_ids(ns).in_use;
691 for (total = 0, next_id = 0; total < in_use; next_id++) {
692 struct kern_ipc_perm *ipc;
693 struct shmid_kernel *shp;
695 ipc = idr_find(&shm_ids(ns).ipcs_idr, next_id);
698 shp = container_of(ipc, struct shmid_kernel, shm_perm);
700 shm_add_rss_swap(shp, rss, swp);
707 * This function handles some shmctl commands which require the rw_mutex
708 * to be held in write mode.
709 * NOTE: no locks must be held, the rw_mutex is taken inside this function.
711 static int shmctl_down(struct ipc_namespace *ns, int shmid, int cmd,
712 struct shmid_ds __user *buf, int version)
714 struct kern_ipc_perm *ipcp;
715 struct shmid64_ds shmid64;
716 struct shmid_kernel *shp;
719 if (cmd == IPC_SET) {
720 if (copy_shmid_from_user(&shmid64, buf, version))
724 ipcp = ipcctl_pre_down(ns, &shm_ids(ns), shmid, cmd,
725 &shmid64.shm_perm, 0);
727 return PTR_ERR(ipcp);
729 shp = container_of(ipcp, struct shmid_kernel, shm_perm);
731 err = security_shm_shmctl(shp, cmd);
736 do_shm_rmid(ns, ipcp);
739 ipc_update_perm(&shmid64.shm_perm, ipcp);
740 shp->shm_ctim = get_seconds();
748 up_write(&shm_ids(ns).rw_mutex);
752 SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
754 struct shmid_kernel *shp;
756 struct ipc_namespace *ns;
758 if (cmd < 0 || shmid < 0) {
763 version = ipc_parse_version(&cmd);
764 ns = current->nsproxy->ipc_ns;
766 switch (cmd) { /* replace with proc interface ? */
769 struct shminfo64 shminfo;
771 err = security_shm_shmctl(NULL, cmd);
775 memset(&shminfo, 0, sizeof(shminfo));
776 shminfo.shmmni = shminfo.shmseg = ns->shm_ctlmni;
777 shminfo.shmmax = ns->shm_ctlmax;
778 shminfo.shmall = ns->shm_ctlall;
780 shminfo.shmmin = SHMMIN;
781 if(copy_shminfo_to_user (buf, &shminfo, version))
784 down_read(&shm_ids(ns).rw_mutex);
785 err = ipc_get_maxid(&shm_ids(ns));
786 up_read(&shm_ids(ns).rw_mutex);
794 struct shm_info shm_info;
796 err = security_shm_shmctl(NULL, cmd);
800 memset(&shm_info, 0, sizeof(shm_info));
801 down_read(&shm_ids(ns).rw_mutex);
802 shm_info.used_ids = shm_ids(ns).in_use;
803 shm_get_stat (ns, &shm_info.shm_rss, &shm_info.shm_swp);
804 shm_info.shm_tot = ns->shm_tot;
805 shm_info.swap_attempts = 0;
806 shm_info.swap_successes = 0;
807 err = ipc_get_maxid(&shm_ids(ns));
808 up_read(&shm_ids(ns).rw_mutex);
809 if (copy_to_user(buf, &shm_info, sizeof(shm_info))) {
814 err = err < 0 ? 0 : err;
820 struct shmid64_ds tbuf;
823 if (cmd == SHM_STAT) {
824 shp = shm_lock(ns, shmid);
829 result = shp->shm_perm.id;
831 shp = shm_lock_check(ns, shmid);
839 if (ipcperms(ns, &shp->shm_perm, S_IRUGO))
841 err = security_shm_shmctl(shp, cmd);
844 memset(&tbuf, 0, sizeof(tbuf));
845 kernel_to_ipc64_perm(&shp->shm_perm, &tbuf.shm_perm);
846 tbuf.shm_segsz = shp->shm_segsz;
847 tbuf.shm_atime = shp->shm_atim;
848 tbuf.shm_dtime = shp->shm_dtim;
849 tbuf.shm_ctime = shp->shm_ctim;
850 tbuf.shm_cpid = shp->shm_cprid;
851 tbuf.shm_lpid = shp->shm_lprid;
852 tbuf.shm_nattch = shp->shm_nattch;
854 if(copy_shmid_to_user (buf, &tbuf, version))
863 struct file *uninitialized_var(shm_file);
865 lru_add_drain_all(); /* drain pagevecs to lru lists */
867 shp = shm_lock_check(ns, shmid);
873 audit_ipc_obj(&(shp->shm_perm));
875 if (!ns_capable(ns->user_ns, CAP_IPC_LOCK)) {
876 uid_t euid = current_euid();
878 if (euid != shp->shm_perm.uid &&
879 euid != shp->shm_perm.cuid)
881 if (cmd == SHM_LOCK && !rlimit(RLIMIT_MEMLOCK))
885 err = security_shm_shmctl(shp, cmd);
890 struct user_struct *user = current_user();
891 if (!is_file_hugepages(shp->shm_file)) {
892 err = shmem_lock(shp->shm_file, 1, user);
893 if (!err && !(shp->shm_perm.mode & SHM_LOCKED)){
894 shp->shm_perm.mode |= SHM_LOCKED;
895 shp->mlock_user = user;
898 } else if (!is_file_hugepages(shp->shm_file)) {
899 shmem_lock(shp->shm_file, 0, shp->mlock_user);
900 shp->shm_perm.mode &= ~SHM_LOCKED;
901 shp->mlock_user = NULL;
908 err = shmctl_down(ns, shmid, cmd, buf, version);
921 * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
923 * NOTE! Despite the name, this is NOT a direct system call entrypoint. The
924 * "raddr" thing points to kernel space, and there has to be a wrapper around
927 long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr)
929 struct shmid_kernel *shp;
937 unsigned long user_addr;
938 struct ipc_namespace *ns;
939 struct shm_file_data *sfd;
946 else if ((addr = (ulong)shmaddr)) {
947 if (addr & (SHMLBA-1)) {
948 if (shmflg & SHM_RND)
949 addr &= ~(SHMLBA-1); /* round down */
951 #ifndef __ARCH_FORCE_SHMLBA
952 if (addr & ~PAGE_MASK)
956 flags = MAP_SHARED | MAP_FIXED;
958 if ((shmflg & SHM_REMAP))
964 if (shmflg & SHM_RDONLY) {
969 prot = PROT_READ | PROT_WRITE;
970 acc_mode = S_IRUGO | S_IWUGO;
971 f_mode = FMODE_READ | FMODE_WRITE;
973 if (shmflg & SHM_EXEC) {
979 * We cannot rely on the fs check since SYSV IPC does have an
980 * additional creator id...
982 ns = current->nsproxy->ipc_ns;
983 shp = shm_lock_check(ns, shmid);
990 if (ipcperms(ns, &shp->shm_perm, acc_mode))
993 err = security_shm_shmat(shp, shmaddr, shmflg);
997 path = shp->shm_file->f_path;
1000 size = i_size_read(path.dentry->d_inode);
1004 sfd = kzalloc(sizeof(*sfd), GFP_KERNEL);
1006 goto out_put_dentry;
1008 file = alloc_file(&path, f_mode,
1009 is_file_hugepages(shp->shm_file) ?
1010 &shm_file_operations_huge :
1011 &shm_file_operations);
1015 file->private_data = sfd;
1016 file->f_mapping = shp->shm_file->f_mapping;
1017 sfd->id = shp->shm_perm.id;
1018 sfd->ns = get_ipc_ns(ns);
1019 sfd->file = shp->shm_file;
1022 down_write(¤t->mm->mmap_sem);
1023 if (addr && !(shmflg & SHM_REMAP)) {
1025 if (find_vma_intersection(current->mm, addr, addr + size))
1028 * If shm segment goes below stack, make sure there is some
1029 * space left for the stack to grow (at least 4 pages).
1031 if (addr < current->mm->start_stack &&
1032 addr > current->mm->start_stack - size - PAGE_SIZE * 5)
1036 user_addr = do_mmap (file, addr, size, prot, flags, 0);
1039 if (IS_ERR_VALUE(user_addr))
1040 err = (long)user_addr;
1042 up_write(¤t->mm->mmap_sem);
1047 down_write(&shm_ids(ns).rw_mutex);
1048 shp = shm_lock(ns, shmid);
1049 BUG_ON(IS_ERR(shp));
1051 if (shm_may_destroy(ns, shp))
1052 shm_destroy(ns, shp);
1055 up_write(&shm_ids(ns).rw_mutex);
1071 SYSCALL_DEFINE3(shmat, int, shmid, char __user *, shmaddr, int, shmflg)
1076 err = do_shmat(shmid, shmaddr, shmflg, &ret);
1079 force_successful_syscall_return();
1084 * detach and kill segment if marked destroyed.
1085 * The work is done in shm_close.
1087 SYSCALL_DEFINE1(shmdt, char __user *, shmaddr)
1089 struct mm_struct *mm = current->mm;
1090 struct vm_area_struct *vma;
1091 unsigned long addr = (unsigned long)shmaddr;
1092 int retval = -EINVAL;
1095 struct vm_area_struct *next;
1098 if (addr & ~PAGE_MASK)
1101 down_write(&mm->mmap_sem);
1104 * This function tries to be smart and unmap shm segments that
1105 * were modified by partial mlock or munmap calls:
1106 * - It first determines the size of the shm segment that should be
1107 * unmapped: It searches for a vma that is backed by shm and that
1108 * started at address shmaddr. It records it's size and then unmaps
1110 * - Then it unmaps all shm vmas that started at shmaddr and that
1111 * are within the initially determined size.
1112 * Errors from do_munmap are ignored: the function only fails if
1113 * it's called with invalid parameters or if it's called to unmap
1114 * a part of a vma. Both calls in this function are for full vmas,
1115 * the parameters are directly copied from the vma itself and always
1116 * valid - therefore do_munmap cannot fail. (famous last words?)
1119 * If it had been mremap()'d, the starting address would not
1120 * match the usual checks anyway. So assume all vma's are
1121 * above the starting address given.
1123 vma = find_vma(mm, addr);
1127 next = vma->vm_next;
1130 * Check if the starting address would match, i.e. it's
1131 * a fragment created by mprotect() and/or munmap(), or it
1132 * otherwise it starts at this address with no hassles.
1134 if ((vma->vm_ops == &shm_vm_ops) &&
1135 (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) {
1138 size = vma->vm_file->f_path.dentry->d_inode->i_size;
1139 do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
1141 * We discovered the size of the shm segment, so
1142 * break out of here and fall through to the next
1143 * loop that uses the size information to stop
1144 * searching for matching vma's.
1154 * We need look no further than the maximum address a fragment
1155 * could possibly have landed at. Also cast things to loff_t to
1156 * prevent overflows and make comparisons vs. equal-width types.
1158 size = PAGE_ALIGN(size);
1159 while (vma && (loff_t)(vma->vm_end - addr) <= size) {
1160 next = vma->vm_next;
1162 /* finding a matching vma now does not alter retval */
1163 if ((vma->vm_ops == &shm_vm_ops) &&
1164 (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff)
1166 do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
1170 #else /* CONFIG_MMU */
1171 /* under NOMMU conditions, the exact address to be destroyed must be
1174 if (vma->vm_start == addr && vma->vm_ops == &shm_vm_ops) {
1175 do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
1181 up_write(&mm->mmap_sem);
1185 #ifdef CONFIG_PROC_FS
1186 static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
1188 struct shmid_kernel *shp = it;
1189 unsigned long rss = 0, swp = 0;
1191 shm_add_rss_swap(shp, &rss, &swp);
1193 #if BITS_PER_LONG <= 32
1194 #define SIZE_SPEC "%10lu"
1196 #define SIZE_SPEC "%21lu"
1199 return seq_printf(s,
1200 "%10d %10d %4o " SIZE_SPEC " %5u %5u "
1201 "%5lu %5u %5u %5u %5u %10lu %10lu %10lu "
1202 SIZE_SPEC " " SIZE_SPEC "\n",