3 * Copyright (C) 1992 Krishna Balasubramanian
5 * Sep 1997 - Call suser() last after "normal" permission checks so we
6 * get BSD style process accounting right.
7 * Occurs in several places in the IPC code.
8 * Chris Evans, <chris@ferret.lmh.ox.ac.uk>
9 * Nov 1999 - ipc helper functions, unified SMP locking
10 * Manfred Spraul <manfred@colorfullife.com>
11 * Oct 2002 - One lock per IPC id. RCU ipc_free for lock-free grow_ary().
12 * Mingming Cao <cmm@us.ibm.com>
13 * Mar 2006 - support for audit of ipc object properties
14 * Dustin Kirkland <dustin.kirkland@us.ibm.com>
15 * Jun 2006 - namespaces ssupport
17 * Pavel Emelianov <xemul@openvz.org>
21 #include <linux/shm.h>
22 #include <linux/init.h>
23 #include <linux/msg.h>
24 #include <linux/vmalloc.h>
25 #include <linux/slab.h>
26 #include <linux/capability.h>
27 #include <linux/highuid.h>
28 #include <linux/security.h>
29 #include <linux/rcupdate.h>
30 #include <linux/workqueue.h>
31 #include <linux/seq_file.h>
32 #include <linux/proc_fs.h>
33 #include <linux/audit.h>
34 #include <linux/nsproxy.h>
36 #include <asm/unistd.h>
40 struct ipc_proc_iface {
44 int (*show)(struct seq_file *, void *);
47 struct ipc_namespace init_ipc_ns = {
49 .refcount = ATOMIC_INIT(2),
53 static struct ipc_namespace *clone_ipc_ns(struct ipc_namespace *old_ns)
56 struct ipc_namespace *ns;
59 ns = kmalloc(sizeof(struct ipc_namespace), GFP_KERNEL);
63 err = sem_init_ns(ns);
66 err = msg_init_ns(ns);
69 err = shm_init_ns(ns);
86 struct ipc_namespace *copy_ipcs(unsigned long flags, struct ipc_namespace *ns)
88 struct ipc_namespace *new_ns;
93 if (!(flags & CLONE_NEWIPC))
96 new_ns = clone_ipc_ns(ns);
102 void free_ipc_ns(struct kref *kref)
104 struct ipc_namespace *ns;
106 ns = container_of(kref, struct ipc_namespace, kref);
114 * ipc_init - initialise IPC subsystem
116 * The various system5 IPC resources (semaphores, messages and shared
117 * memory) are initialised
120 static int __init ipc_init(void)
127 __initcall(ipc_init);
130 * ipc_init_ids - initialise IPC identifiers
131 * @ids: Identifier set
133 * Set up the sequence range to use for the ipc identifier range (limited
134 * below IPCMNI) then initialise the ids idr.
137 void ipc_init_ids(struct ipc_ids *ids)
139 mutex_init(&ids->mutex);
144 int seq_limit = INT_MAX/SEQ_MULTIPLIER;
145 if(seq_limit > USHRT_MAX)
146 ids->seq_max = USHRT_MAX;
148 ids->seq_max = seq_limit;
151 idr_init(&ids->ipcs_idr);
154 #ifdef CONFIG_PROC_FS
155 static const struct file_operations sysvipc_proc_fops;
157 * ipc_init_proc_interface - Create a proc interface for sysipc types using a seq_file interface.
158 * @path: Path in procfs
159 * @header: Banner to be printed at the beginning of the file.
160 * @ids: ipc id table to iterate.
161 * @show: show routine.
163 void __init ipc_init_proc_interface(const char *path, const char *header,
164 int ids, int (*show)(struct seq_file *, void *))
166 struct proc_dir_entry *pde;
167 struct ipc_proc_iface *iface;
169 iface = kmalloc(sizeof(*iface), GFP_KERNEL);
173 iface->header = header;
177 pde = create_proc_entry(path,
178 S_IRUGO, /* world readable */
179 NULL /* parent dir */);
182 pde->proc_fops = &sysvipc_proc_fops;
190 * ipc_findkey - find a key in an ipc identifier set
191 * @ids: Identifier set
192 * @key: The key to find
194 * Requires ipc_ids.mutex locked.
195 * Returns the LOCKED pointer to the ipc structure if found or NULL
197 * If key is found ipc points to the owning ipc structure
200 static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key)
202 struct kern_ipc_perm *ipc;
206 for (total = 0, next_id = 0; total < ids->in_use; next_id++) {
207 ipc = idr_find(&ids->ipcs_idr, next_id);
212 if (ipc->key != key) {
217 ipc_lock_by_ptr(ipc);
225 * ipc_get_maxid - get the last assigned id
226 * @ids: IPC identifier set
228 * Called with ipc_ids.mutex held.
231 int ipc_get_maxid(struct ipc_ids *ids)
233 struct kern_ipc_perm *ipc;
237 if (ids->in_use == 0)
240 if (ids->in_use == IPCMNI)
243 /* Look for the last assigned id */
245 for (id = 0; id < IPCMNI && total < ids->in_use; id++) {
246 ipc = idr_find(&ids->ipcs_idr, id);
256 * ipc_addid - add an IPC identifier
257 * @ids: IPC identifier set
258 * @new: new IPC permission set
259 * @size: limit for the number of used ids
261 * Add an entry 'new' to the IPC ids idr. The permissions object is
262 * initialised and the first free entry is set up and the id assigned
263 * is returned. The 'new' entry is returned in a locked state on success.
264 * On failure the entry is not locked and -1 is returned.
266 * Called with ipc_ids.mutex held.
269 int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
276 if (ids->in_use >= size)
279 err = idr_get_new(&ids->ipcs_idr, new, &id);
285 new->cuid = new->uid = current->euid;
286 new->gid = new->cgid = current->egid;
288 new->seq = ids->seq++;
289 if(ids->seq > ids->seq_max)
292 spin_lock_init(&new->lock);
295 spin_lock(&new->lock);
300 * ipcget_new - create a new ipc object
302 * @ids: IPC identifer set
303 * @ops: the actual creation routine to call
304 * @params: its parameters
306 * This routine is called by sys_msgget, sys_semget() and sys_shmget()
307 * when the key is IPC_PRIVATE.
309 int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
310 struct ipc_ops *ops, struct ipc_params *params)
314 err = idr_pre_get(&ids->ipcs_idr, GFP_KERNEL);
319 mutex_lock(&ids->mutex);
320 err = ops->getnew(ns, params);
321 mutex_unlock(&ids->mutex);
327 * ipc_check_perms - check security and permissions for an IPC
328 * @ipcp: ipc permission set
329 * @ops: the actual security routine to call
330 * @params: its parameters
332 * This routine is called by sys_msgget(), sys_semget() and sys_shmget()
333 * when the key is not IPC_PRIVATE and that key already exists in the
336 * On success, the IPC id is returned.
338 * It is called with ipc_ids.mutex and ipcp->lock held.
340 static int ipc_check_perms(struct kern_ipc_perm *ipcp, struct ipc_ops *ops,
341 struct ipc_params *params)
345 if (ipcperms(ipcp, params->flg))
348 err = ops->associate(ipcp, params->flg);
357 * ipcget_public - get an ipc object or create a new one
359 * @ids: IPC identifer set
360 * @ops: the actual creation routine to call
361 * @params: its parameters
363 * This routine is called by sys_msgget, sys_semget() and sys_shmget()
364 * when the key is not IPC_PRIVATE.
365 * It adds a new entry if the key is not found and does some permission
366 * / security checkings if the key is found.
368 * On success, the ipc id is returned.
370 int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
371 struct ipc_ops *ops, struct ipc_params *params)
373 struct kern_ipc_perm *ipcp;
374 int flg = params->flg;
377 err = idr_pre_get(&ids->ipcs_idr, GFP_KERNEL);
379 mutex_lock(&ids->mutex);
380 ipcp = ipc_findkey(ids, params->key);
383 if (!(flg & IPC_CREAT))
388 err = ops->getnew(ns, params);
390 /* ipc object has been locked by ipc_findkey() */
392 if (flg & IPC_CREAT && flg & IPC_EXCL)
396 if (ops->more_checks)
397 err = ops->more_checks(ipcp, params);
400 * ipc_check_perms returns the IPC id on
403 err = ipc_check_perms(ipcp, ops, params);
407 mutex_unlock(&ids->mutex);
414 * ipc_rmid - remove an IPC identifier
415 * @ids: IPC identifier set
416 * @ipcp: ipc perm structure containing the identifier to remove
418 * ipc_ids.mutex and the spinlock for this ID are held before this
419 * function is called, and remain locked on the exit.
422 void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
424 int lid = ipcid_to_idx(ipcp->id);
426 idr_remove(&ids->ipcs_idr, lid);
436 * ipc_alloc - allocate ipc space
437 * @size: size desired
439 * Allocate memory from the appropriate pools and return a pointer to it.
440 * NULL is returned if the allocation fails
443 void* ipc_alloc(int size)
449 out = kmalloc(size, GFP_KERNEL);
454 * ipc_free - free ipc space
455 * @ptr: pointer returned by ipc_alloc
456 * @size: size of block
458 * Free a block created with ipc_alloc(). The caller must know the size
459 * used in the allocation call.
462 void ipc_free(void* ptr, int size)
472 * There are three headers that are prepended to the actual allocation:
473 * - during use: ipc_rcu_hdr.
474 * - during the rcu grace period: ipc_rcu_grace.
475 * - [only if vmalloc]: ipc_rcu_sched.
476 * Their lifetime doesn't overlap, thus the headers share the same memory.
477 * Unlike a normal union, they are right-aligned, thus some container_of
478 * forward/backward casting is necessary:
491 /* "void *" makes sure alignment of following data is sane. */
497 struct work_struct work;
498 /* "void *" makes sure alignment of following data is sane. */
502 #define HDRLEN_KMALLOC (sizeof(struct ipc_rcu_grace) > sizeof(struct ipc_rcu_hdr) ? \
503 sizeof(struct ipc_rcu_grace) : sizeof(struct ipc_rcu_hdr))
504 #define HDRLEN_VMALLOC (sizeof(struct ipc_rcu_sched) > HDRLEN_KMALLOC ? \
505 sizeof(struct ipc_rcu_sched) : HDRLEN_KMALLOC)
507 static inline int rcu_use_vmalloc(int size)
509 /* Too big for a single page? */
510 if (HDRLEN_KMALLOC + size > PAGE_SIZE)
516 * ipc_rcu_alloc - allocate ipc and rcu space
517 * @size: size desired
519 * Allocate memory for the rcu header structure + the object.
520 * Returns the pointer to the object.
521 * NULL is returned if the allocation fails.
524 void* ipc_rcu_alloc(int size)
528 * We prepend the allocation with the rcu struct, and
529 * workqueue if necessary (for vmalloc).
531 if (rcu_use_vmalloc(size)) {
532 out = vmalloc(HDRLEN_VMALLOC + size);
534 out += HDRLEN_VMALLOC;
535 container_of(out, struct ipc_rcu_hdr, data)->is_vmalloc = 1;
536 container_of(out, struct ipc_rcu_hdr, data)->refcount = 1;
539 out = kmalloc(HDRLEN_KMALLOC + size, GFP_KERNEL);
541 out += HDRLEN_KMALLOC;
542 container_of(out, struct ipc_rcu_hdr, data)->is_vmalloc = 0;
543 container_of(out, struct ipc_rcu_hdr, data)->refcount = 1;
550 void ipc_rcu_getref(void *ptr)
552 container_of(ptr, struct ipc_rcu_hdr, data)->refcount++;
555 static void ipc_do_vfree(struct work_struct *work)
557 vfree(container_of(work, struct ipc_rcu_sched, work));
561 * ipc_schedule_free - free ipc + rcu space
562 * @head: RCU callback structure for queued work
564 * Since RCU callback function is called in bh,
565 * we need to defer the vfree to schedule_work().
567 static void ipc_schedule_free(struct rcu_head *head)
569 struct ipc_rcu_grace *grace;
570 struct ipc_rcu_sched *sched;
572 grace = container_of(head, struct ipc_rcu_grace, rcu);
573 sched = container_of(&(grace->data[0]), struct ipc_rcu_sched,
576 INIT_WORK(&sched->work, ipc_do_vfree);
577 schedule_work(&sched->work);
581 * ipc_immediate_free - free ipc + rcu space
582 * @head: RCU callback structure that contains pointer to be freed
584 * Free from the RCU callback context.
586 static void ipc_immediate_free(struct rcu_head *head)
588 struct ipc_rcu_grace *free =
589 container_of(head, struct ipc_rcu_grace, rcu);
593 void ipc_rcu_putref(void *ptr)
595 if (--container_of(ptr, struct ipc_rcu_hdr, data)->refcount > 0)
598 if (container_of(ptr, struct ipc_rcu_hdr, data)->is_vmalloc) {
599 call_rcu(&container_of(ptr, struct ipc_rcu_grace, data)->rcu,
602 call_rcu(&container_of(ptr, struct ipc_rcu_grace, data)->rcu,
608 * ipcperms - check IPC permissions
609 * @ipcp: IPC permission set
610 * @flag: desired permission set.
612 * Check user, group, other permissions for access
613 * to ipc resources. return 0 if allowed
616 int ipcperms (struct kern_ipc_perm *ipcp, short flag)
617 { /* flag will most probably be 0 or S_...UGO from <linux/stat.h> */
618 int requested_mode, granted_mode, err;
620 if (unlikely((err = audit_ipc_obj(ipcp))))
622 requested_mode = (flag >> 6) | (flag >> 3) | flag;
623 granted_mode = ipcp->mode;
624 if (current->euid == ipcp->cuid || current->euid == ipcp->uid)
626 else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid))
628 /* is there some bit set in requested_mode but not in granted_mode? */
629 if ((requested_mode & ~granted_mode & 0007) &&
630 !capable(CAP_IPC_OWNER))
633 return security_ipc_permission(ipcp, flag);
637 * Functions to convert between the kern_ipc_perm structure and the
638 * old/new ipc_perm structures
642 * kernel_to_ipc64_perm - convert kernel ipc permissions to user
643 * @in: kernel permissions
644 * @out: new style IPC permissions
646 * Turn the kernel object @in into a set of permissions descriptions
647 * for returning to userspace (@out).
651 void kernel_to_ipc64_perm (struct kern_ipc_perm *in, struct ipc64_perm *out)
656 out->cuid = in->cuid;
657 out->cgid = in->cgid;
658 out->mode = in->mode;
663 * ipc64_perm_to_ipc_perm - convert new ipc permissions to old
664 * @in: new style IPC permissions
665 * @out: old style IPC permissions
667 * Turn the new style permissions object @in into a compatibility
668 * object and store it into the @out pointer.
671 void ipc64_perm_to_ipc_perm (struct ipc64_perm *in, struct ipc_perm *out)
674 SET_UID(out->uid, in->uid);
675 SET_GID(out->gid, in->gid);
676 SET_UID(out->cuid, in->cuid);
677 SET_GID(out->cgid, in->cgid);
678 out->mode = in->mode;
683 * ipc_lock - Lock an ipc structure
684 * @ids: IPC identifier set
685 * @id: ipc id to look for
687 * Look for an id in the ipc ids idr and lock the associated ipc object.
689 * ipc_ids.mutex is not necessarily held before this function is called,
690 * that's why we enter a RCU read section.
691 * The ipc object is locked on exit.
694 struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
696 struct kern_ipc_perm *out;
697 int lid = ipcid_to_idx(id);
700 out = idr_find(&ids->ipcs_idr, lid);
703 return ERR_PTR(-EINVAL);
706 spin_lock(&out->lock);
708 /* ipc_rmid() may have already freed the ID while ipc_lock
709 * was spinning: here verify that the structure is still valid
712 spin_unlock(&out->lock);
714 return ERR_PTR(-EINVAL);
720 #ifdef __ARCH_WANT_IPC_PARSE_VERSION
724 * ipc_parse_version - IPC call version
725 * @cmd: pointer to command
727 * Return IPC_64 for new style IPC and IPC_OLD for old style IPC.
728 * The @cmd value is turned from an encoding command and version into
729 * just the command code.
732 int ipc_parse_version (int *cmd)
742 #endif /* __ARCH_WANT_IPC_PARSE_VERSION */
744 #ifdef CONFIG_PROC_FS
745 struct ipc_proc_iter {
746 struct ipc_namespace *ns;
747 struct ipc_proc_iface *iface;
751 * This routine locks the ipc structure found at least at position pos.
753 struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos,
756 struct kern_ipc_perm *ipc;
760 for (id = 0; id < pos && total < ids->in_use; id++) {
761 ipc = idr_find(&ids->ipcs_idr, id);
766 if (total >= ids->in_use)
769 for ( ; pos < IPCMNI; pos++) {
770 ipc = idr_find(&ids->ipcs_idr, pos);
773 ipc_lock_by_ptr(ipc);
778 /* Out of range - return NULL to terminate iteration */
782 static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
784 struct ipc_proc_iter *iter = s->private;
785 struct ipc_proc_iface *iface = iter->iface;
786 struct kern_ipc_perm *ipc = it;
788 /* If we had an ipc id locked before, unlock it */
789 if (ipc && ipc != SEQ_START_TOKEN)
792 return sysvipc_find_ipc(iter->ns->ids[iface->ids], *pos, pos);
796 * File positions: pos 0 -> header, pos n -> ipc id = n - 1.
797 * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START.
799 static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
801 struct ipc_proc_iter *iter = s->private;
802 struct ipc_proc_iface *iface = iter->iface;
805 ids = iter->ns->ids[iface->ids];
808 * Take the lock - this will be released by the corresponding
811 mutex_lock(&ids->mutex);
813 /* pos < 0 is invalid */
817 /* pos == 0 means header */
819 return SEQ_START_TOKEN;
821 /* Find the (pos-1)th ipc */
822 return sysvipc_find_ipc(ids, *pos - 1, pos);
825 static void sysvipc_proc_stop(struct seq_file *s, void *it)
827 struct kern_ipc_perm *ipc = it;
828 struct ipc_proc_iter *iter = s->private;
829 struct ipc_proc_iface *iface = iter->iface;
832 /* If we had a locked structure, release it */
833 if (ipc && ipc != SEQ_START_TOKEN)
836 ids = iter->ns->ids[iface->ids];
837 /* Release the lock we took in start() */
838 mutex_unlock(&ids->mutex);
841 static int sysvipc_proc_show(struct seq_file *s, void *it)
843 struct ipc_proc_iter *iter = s->private;
844 struct ipc_proc_iface *iface = iter->iface;
846 if (it == SEQ_START_TOKEN)
847 return seq_puts(s, iface->header);
849 return iface->show(s, it);
852 static struct seq_operations sysvipc_proc_seqops = {
853 .start = sysvipc_proc_start,
854 .stop = sysvipc_proc_stop,
855 .next = sysvipc_proc_next,
856 .show = sysvipc_proc_show,
859 static int sysvipc_proc_open(struct inode *inode, struct file *file)
862 struct seq_file *seq;
863 struct ipc_proc_iter *iter;
866 iter = kmalloc(sizeof(*iter), GFP_KERNEL);
870 ret = seq_open(file, &sysvipc_proc_seqops);
874 seq = file->private_data;
877 iter->iface = PDE(inode)->data;
878 iter->ns = get_ipc_ns(current->nsproxy->ipc_ns);
886 static int sysvipc_proc_release(struct inode *inode, struct file *file)
888 struct seq_file *seq = file->private_data;
889 struct ipc_proc_iter *iter = seq->private;
890 put_ipc_ns(iter->ns);
891 return seq_release_private(inode, file);
894 static const struct file_operations sysvipc_proc_fops = {
895 .open = sysvipc_proc_open,
898 .release = sysvipc_proc_release,
900 #endif /* CONFIG_PROC_FS */