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>
35 #include <linux/rwsem.h>
36 #include <linux/memory.h>
37 #include <linux/ipc_namespace.h>
39 #include <asm/unistd.h>
43 struct ipc_proc_iface {
47 int (*show)(struct seq_file *, void *);
50 #ifdef CONFIG_MEMORY_HOTPLUG
52 static void ipc_memory_notifier(struct work_struct *work)
54 ipcns_notify(IPCNS_MEMCHANGED);
57 static DECLARE_WORK(ipc_memory_wq, ipc_memory_notifier);
60 static int ipc_memory_callback(struct notifier_block *self,
61 unsigned long action, void *arg)
64 case MEM_ONLINE: /* memory successfully brought online */
65 case MEM_OFFLINE: /* or offline: it's time to recompute msgmni */
67 * This is done by invoking the ipcns notifier chain with the
68 * IPC_MEMCHANGED event.
69 * In order not to keep the lock on the hotplug memory chain
70 * for too long, queue a work item that will, when waken up,
71 * activate the ipcns notification chain.
72 * No need to keep several ipc work items on the queue.
74 if (!work_pending(&ipc_memory_wq))
75 schedule_work(&ipc_memory_wq);
77 case MEM_GOING_ONLINE:
78 case MEM_GOING_OFFLINE:
79 case MEM_CANCEL_ONLINE:
80 case MEM_CANCEL_OFFLINE:
88 #endif /* CONFIG_MEMORY_HOTPLUG */
91 * ipc_init - initialise IPC subsystem
93 * The various system5 IPC resources (semaphores, messages and shared
94 * memory) are initialised
95 * A callback routine is registered into the memory hotplug notifier
96 * chain: since msgmni scales to lowmem this callback routine will be
97 * called upon successful memory add / remove to recompute msmgni.
100 static int __init ipc_init(void)
105 hotplug_memory_notifier(ipc_memory_callback, IPC_CALLBACK_PRI);
106 register_ipcns_notifier(&init_ipc_ns);
109 __initcall(ipc_init);
111 void __ipc_init_ids(struct ipc_ids *ids)
116 int seq_limit = INT_MAX/SEQ_MULTIPLIER;
117 if (seq_limit > USHRT_MAX)
118 ids->seq_max = USHRT_MAX;
120 ids->seq_max = seq_limit;
123 idr_init(&ids->ipcs_idr);
127 * ipc_init_ids - initialise IPC identifiers
128 * @ids: Identifier set
130 * Set up the sequence range to use for the ipc identifier range (limited
131 * below IPCMNI) then initialise the ids idr.
134 void ipc_init_ids(struct ipc_ids *ids)
136 init_rwsem(&ids->rw_mutex);
140 #ifdef CONFIG_PROC_FS
141 static const struct file_operations sysvipc_proc_fops;
143 * ipc_init_proc_interface - Create a proc interface for sysipc types using a seq_file interface.
144 * @path: Path in procfs
145 * @header: Banner to be printed at the beginning of the file.
146 * @ids: ipc id table to iterate.
147 * @show: show routine.
149 void __init ipc_init_proc_interface(const char *path, const char *header,
150 int ids, int (*show)(struct seq_file *, void *))
152 struct proc_dir_entry *pde;
153 struct ipc_proc_iface *iface;
155 iface = kmalloc(sizeof(*iface), GFP_KERNEL);
159 iface->header = header;
163 pde = proc_create_data(path,
164 S_IRUGO, /* world readable */
165 NULL, /* parent dir */
175 * ipc_findkey - find a key in an ipc identifier set
176 * @ids: Identifier set
177 * @key: The key to find
179 * Requires ipc_ids.rw_mutex locked.
180 * Returns the LOCKED pointer to the ipc structure if found or NULL
182 * If key is found ipc points to the owning ipc structure
185 static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key)
187 struct kern_ipc_perm *ipc;
191 for (total = 0, next_id = 0; total < ids->in_use; next_id++) {
192 ipc = idr_find(&ids->ipcs_idr, next_id);
197 if (ipc->key != key) {
202 ipc_lock_by_ptr(ipc);
210 * ipc_get_maxid - get the last assigned id
211 * @ids: IPC identifier set
213 * Called with ipc_ids.rw_mutex held.
216 int ipc_get_maxid(struct ipc_ids *ids)
218 struct kern_ipc_perm *ipc;
222 if (ids->in_use == 0)
225 if (ids->in_use == IPCMNI)
228 /* Look for the last assigned id */
230 for (id = 0; id < IPCMNI && total < ids->in_use; id++) {
231 ipc = idr_find(&ids->ipcs_idr, id);
241 * ipc_addid - add an IPC identifier
242 * @ids: IPC identifier set
243 * @new: new IPC permission set
244 * @size: limit for the number of used ids
246 * Add an entry 'new' to the IPC ids idr. The permissions object is
247 * initialised and the first free entry is set up and the id assigned
248 * is returned. The 'new' entry is returned in a locked state on success.
249 * On failure the entry is not locked and a negative err-code is returned.
251 * Called with ipc_ids.rw_mutex held as a writer.
254 int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
263 if (ids->in_use >= size)
266 spin_lock_init(&new->lock);
269 spin_lock(&new->lock);
271 err = idr_get_new(&ids->ipcs_idr, new, &id);
273 spin_unlock(&new->lock);
280 current_euid_egid(&euid, &egid);
281 new->cuid = new->uid = euid;
282 new->gid = new->cgid = egid;
284 new->seq = ids->seq++;
285 if(ids->seq > ids->seq_max)
288 new->id = ipc_buildid(id, new->seq);
293 * ipcget_new - create a new ipc object
295 * @ids: IPC identifer set
296 * @ops: the actual creation routine to call
297 * @params: its parameters
299 * This routine is called by sys_msgget, sys_semget() and sys_shmget()
300 * when the key is IPC_PRIVATE.
302 static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
303 struct ipc_ops *ops, struct ipc_params *params)
307 err = idr_pre_get(&ids->ipcs_idr, GFP_KERNEL);
312 down_write(&ids->rw_mutex);
313 err = ops->getnew(ns, params);
314 up_write(&ids->rw_mutex);
323 * ipc_check_perms - check security and permissions for an IPC
325 * @ipcp: ipc permission set
326 * @ops: the actual security routine to call
327 * @params: its parameters
329 * This routine is called by sys_msgget(), sys_semget() and sys_shmget()
330 * when the key is not IPC_PRIVATE and that key already exists in the
333 * On success, the IPC id is returned.
335 * It is called with ipc_ids.rw_mutex and ipcp->lock held.
337 static int ipc_check_perms(struct ipc_namespace *ns,
338 struct kern_ipc_perm *ipcp,
340 struct ipc_params *params)
344 if (ipcperms(ns, ipcp, params->flg))
347 err = ops->associate(ipcp, params->flg);
356 * ipcget_public - get an ipc object or create a new one
358 * @ids: IPC identifer set
359 * @ops: the actual creation routine to call
360 * @params: its parameters
362 * This routine is called by sys_msgget, sys_semget() and sys_shmget()
363 * when the key is not IPC_PRIVATE.
364 * It adds a new entry if the key is not found and does some permission
365 * / security checkings if the key is found.
367 * On success, the ipc id is returned.
369 static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
370 struct ipc_ops *ops, struct ipc_params *params)
372 struct kern_ipc_perm *ipcp;
373 int flg = params->flg;
376 err = idr_pre_get(&ids->ipcs_idr, GFP_KERNEL);
379 * Take the lock as a writer since we are potentially going to add
380 * a new entry + read locks are not "upgradable"
382 down_write(&ids->rw_mutex);
383 ipcp = ipc_findkey(ids, params->key);
386 if (!(flg & IPC_CREAT))
391 err = ops->getnew(ns, params);
393 /* ipc object has been locked by ipc_findkey() */
395 if (flg & IPC_CREAT && flg & IPC_EXCL)
399 if (ops->more_checks)
400 err = ops->more_checks(ipcp, params);
403 * ipc_check_perms returns the IPC id on
406 err = ipc_check_perms(ns, ipcp, ops, params);
410 up_write(&ids->rw_mutex);
420 * ipc_rmid - remove an IPC identifier
421 * @ids: IPC identifier set
422 * @ipcp: ipc perm structure containing the identifier to remove
424 * ipc_ids.rw_mutex (as a writer) and the spinlock for this ID are held
425 * before this function is called, and remain locked on the exit.
428 void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
430 int lid = ipcid_to_idx(ipcp->id);
432 idr_remove(&ids->ipcs_idr, lid);
442 * ipc_alloc - allocate ipc space
443 * @size: size desired
445 * Allocate memory from the appropriate pools and return a pointer to it.
446 * NULL is returned if the allocation fails
449 void* ipc_alloc(int size)
455 out = kmalloc(size, GFP_KERNEL);
460 * ipc_free - free ipc space
461 * @ptr: pointer returned by ipc_alloc
462 * @size: size of block
464 * Free a block created with ipc_alloc(). The caller must know the size
465 * used in the allocation call.
468 void ipc_free(void* ptr, int size)
478 * There are three headers that are prepended to the actual allocation:
479 * - during use: ipc_rcu_hdr.
480 * - during the rcu grace period: ipc_rcu_grace.
481 * - [only if vmalloc]: ipc_rcu_sched.
482 * Their lifetime doesn't overlap, thus the headers share the same memory.
483 * Unlike a normal union, they are right-aligned, thus some container_of
484 * forward/backward casting is necessary:
497 /* "void *" makes sure alignment of following data is sane. */
503 struct work_struct work;
504 /* "void *" makes sure alignment of following data is sane. */
508 #define HDRLEN_KMALLOC (sizeof(struct ipc_rcu_grace) > sizeof(struct ipc_rcu_hdr) ? \
509 sizeof(struct ipc_rcu_grace) : sizeof(struct ipc_rcu_hdr))
510 #define HDRLEN_VMALLOC (sizeof(struct ipc_rcu_sched) > HDRLEN_KMALLOC ? \
511 sizeof(struct ipc_rcu_sched) : HDRLEN_KMALLOC)
513 static inline int rcu_use_vmalloc(int size)
515 /* Too big for a single page? */
516 if (HDRLEN_KMALLOC + size > PAGE_SIZE)
522 * ipc_rcu_alloc - allocate ipc and rcu space
523 * @size: size desired
525 * Allocate memory for the rcu header structure + the object.
526 * Returns the pointer to the object.
527 * NULL is returned if the allocation fails.
530 void* ipc_rcu_alloc(int size)
534 * We prepend the allocation with the rcu struct, and
535 * workqueue if necessary (for vmalloc).
537 if (rcu_use_vmalloc(size)) {
538 out = vmalloc(HDRLEN_VMALLOC + size);
540 out += HDRLEN_VMALLOC;
541 container_of(out, struct ipc_rcu_hdr, data)->is_vmalloc = 1;
542 container_of(out, struct ipc_rcu_hdr, data)->refcount = 1;
545 out = kmalloc(HDRLEN_KMALLOC + size, GFP_KERNEL);
547 out += HDRLEN_KMALLOC;
548 container_of(out, struct ipc_rcu_hdr, data)->is_vmalloc = 0;
549 container_of(out, struct ipc_rcu_hdr, data)->refcount = 1;
556 void ipc_rcu_getref(void *ptr)
558 container_of(ptr, struct ipc_rcu_hdr, data)->refcount++;
561 static void ipc_do_vfree(struct work_struct *work)
563 vfree(container_of(work, struct ipc_rcu_sched, work));
567 * ipc_schedule_free - free ipc + rcu space
568 * @head: RCU callback structure for queued work
570 * Since RCU callback function is called in bh,
571 * we need to defer the vfree to schedule_work().
573 static void ipc_schedule_free(struct rcu_head *head)
575 struct ipc_rcu_grace *grace;
576 struct ipc_rcu_sched *sched;
578 grace = container_of(head, struct ipc_rcu_grace, rcu);
579 sched = container_of(&(grace->data[0]), struct ipc_rcu_sched,
582 INIT_WORK(&sched->work, ipc_do_vfree);
583 schedule_work(&sched->work);
586 void ipc_rcu_putref(void *ptr)
588 if (--container_of(ptr, struct ipc_rcu_hdr, data)->refcount > 0)
591 if (container_of(ptr, struct ipc_rcu_hdr, data)->is_vmalloc) {
592 call_rcu(&container_of(ptr, struct ipc_rcu_grace, data)->rcu,
595 kfree_rcu(container_of(ptr, struct ipc_rcu_grace, data), rcu);
600 * ipcperms - check IPC permissions
602 * @ipcp: IPC permission set
603 * @flag: desired permission set.
605 * Check user, group, other permissions for access
606 * to ipc resources. return 0 if allowed
608 * @flag will most probably be 0 or S_...UGO from <linux/stat.h>
611 int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flag)
613 uid_t euid = current_euid();
614 int requested_mode, granted_mode;
617 requested_mode = (flag >> 6) | (flag >> 3) | flag;
618 granted_mode = ipcp->mode;
619 if (euid == ipcp->cuid ||
622 else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid))
624 /* is there some bit set in requested_mode but not in granted_mode? */
625 if ((requested_mode & ~granted_mode & 0007) &&
626 !ns_capable(ns->user_ns, CAP_IPC_OWNER))
629 return security_ipc_permission(ipcp, flag);
633 * Functions to convert between the kern_ipc_perm structure and the
634 * old/new ipc_perm structures
638 * kernel_to_ipc64_perm - convert kernel ipc permissions to user
639 * @in: kernel permissions
640 * @out: new style IPC permissions
642 * Turn the kernel object @in into a set of permissions descriptions
643 * for returning to userspace (@out).
647 void kernel_to_ipc64_perm (struct kern_ipc_perm *in, struct ipc64_perm *out)
652 out->cuid = in->cuid;
653 out->cgid = in->cgid;
654 out->mode = in->mode;
659 * ipc64_perm_to_ipc_perm - convert new ipc permissions to old
660 * @in: new style IPC permissions
661 * @out: old style IPC permissions
663 * Turn the new style permissions object @in into a compatibility
664 * object and store it into the @out pointer.
667 void ipc64_perm_to_ipc_perm (struct ipc64_perm *in, struct ipc_perm *out)
670 SET_UID(out->uid, in->uid);
671 SET_GID(out->gid, in->gid);
672 SET_UID(out->cuid, in->cuid);
673 SET_GID(out->cgid, in->cgid);
674 out->mode = in->mode;
679 * ipc_lock - Lock an ipc structure without rw_mutex held
680 * @ids: IPC identifier set
681 * @id: ipc id to look for
683 * Look for an id in the ipc ids idr and lock the associated ipc object.
685 * The ipc object is locked on exit.
688 struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
690 struct kern_ipc_perm *out;
691 int lid = ipcid_to_idx(id);
694 out = idr_find(&ids->ipcs_idr, lid);
697 return ERR_PTR(-EINVAL);
700 spin_lock(&out->lock);
702 /* ipc_rmid() may have already freed the ID while ipc_lock
703 * was spinning: here verify that the structure is still valid
706 spin_unlock(&out->lock);
708 return ERR_PTR(-EINVAL);
714 struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids, int id)
716 struct kern_ipc_perm *out;
718 out = ipc_lock(ids, id);
722 if (ipc_checkid(out, id)) {
724 return ERR_PTR(-EIDRM);
731 * ipcget - Common sys_*get() code
733 * @ids : IPC identifier set
734 * @ops : operations to be called on ipc object creation, permission checks
736 * @params : the parameters needed by the previous operations.
738 * Common routine called by sys_msgget(), sys_semget() and sys_shmget().
740 int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
741 struct ipc_ops *ops, struct ipc_params *params)
743 if (params->key == IPC_PRIVATE)
744 return ipcget_new(ns, ids, ops, params);
746 return ipcget_public(ns, ids, ops, params);
750 * ipc_update_perm - update the permissions of an IPC.
751 * @in: the permission given as input.
752 * @out: the permission of the ipc to set.
754 void ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out)
758 out->mode = (out->mode & ~S_IRWXUGO)
759 | (in->mode & S_IRWXUGO);
763 * ipcctl_pre_down - retrieve an ipc and check permissions for some IPC_XXX cmd
764 * @ns: the ipc namespace
765 * @ids: the table of ids where to look for the ipc
766 * @id: the id of the ipc to retrieve
767 * @cmd: the cmd to check
768 * @perm: the permission to set
769 * @extra_perm: one extra permission parameter used by msq
771 * This function does some common audit and permissions check for some IPC_XXX
772 * cmd and is called from semctl_down, shmctl_down and msgctl_down.
773 * It must be called without any lock held and
774 * - retrieves the ipc with the given id in the given table.
775 * - performs some audit and permission check, depending on the given cmd
776 * - returns the ipc with both ipc and rw_mutex locks held in case of success
777 * or an err-code without any lock held otherwise.
779 struct kern_ipc_perm *ipcctl_pre_down(struct ipc_namespace *ns,
780 struct ipc_ids *ids, int id, int cmd,
781 struct ipc64_perm *perm, int extra_perm)
783 struct kern_ipc_perm *ipcp;
787 down_write(&ids->rw_mutex);
788 ipcp = ipc_lock_check(ids, id);
796 audit_ipc_set_perm(extra_perm, perm->uid,
797 perm->gid, perm->mode);
799 euid = current_euid();
800 if (euid == ipcp->cuid || euid == ipcp->uid ||
801 ns_capable(ns->user_ns, CAP_SYS_ADMIN))
807 up_write(&ids->rw_mutex);
811 #ifdef __ARCH_WANT_IPC_PARSE_VERSION
815 * ipc_parse_version - IPC call version
816 * @cmd: pointer to command
818 * Return IPC_64 for new style IPC and IPC_OLD for old style IPC.
819 * The @cmd value is turned from an encoding command and version into
820 * just the command code.
823 int ipc_parse_version (int *cmd)
833 #endif /* __ARCH_WANT_IPC_PARSE_VERSION */
835 #ifdef CONFIG_PROC_FS
836 struct ipc_proc_iter {
837 struct ipc_namespace *ns;
838 struct ipc_proc_iface *iface;
842 * This routine locks the ipc structure found at least at position pos.
844 static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos,
847 struct kern_ipc_perm *ipc;
851 for (id = 0; id < pos && total < ids->in_use; id++) {
852 ipc = idr_find(&ids->ipcs_idr, id);
857 if (total >= ids->in_use)
860 for ( ; pos < IPCMNI; pos++) {
861 ipc = idr_find(&ids->ipcs_idr, pos);
864 ipc_lock_by_ptr(ipc);
869 /* Out of range - return NULL to terminate iteration */
873 static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
875 struct ipc_proc_iter *iter = s->private;
876 struct ipc_proc_iface *iface = iter->iface;
877 struct kern_ipc_perm *ipc = it;
879 /* If we had an ipc id locked before, unlock it */
880 if (ipc && ipc != SEQ_START_TOKEN)
883 return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos);
887 * File positions: pos 0 -> header, pos n -> ipc id = n - 1.
888 * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START.
890 static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
892 struct ipc_proc_iter *iter = s->private;
893 struct ipc_proc_iface *iface = iter->iface;
896 ids = &iter->ns->ids[iface->ids];
899 * Take the lock - this will be released by the corresponding
902 down_read(&ids->rw_mutex);
904 /* pos < 0 is invalid */
908 /* pos == 0 means header */
910 return SEQ_START_TOKEN;
912 /* Find the (pos-1)th ipc */
913 return sysvipc_find_ipc(ids, *pos - 1, pos);
916 static void sysvipc_proc_stop(struct seq_file *s, void *it)
918 struct kern_ipc_perm *ipc = it;
919 struct ipc_proc_iter *iter = s->private;
920 struct ipc_proc_iface *iface = iter->iface;
923 /* If we had a locked structure, release it */
924 if (ipc && ipc != SEQ_START_TOKEN)
927 ids = &iter->ns->ids[iface->ids];
928 /* Release the lock we took in start() */
929 up_read(&ids->rw_mutex);
932 static int sysvipc_proc_show(struct seq_file *s, void *it)
934 struct ipc_proc_iter *iter = s->private;
935 struct ipc_proc_iface *iface = iter->iface;
937 if (it == SEQ_START_TOKEN)
938 return seq_puts(s, iface->header);
940 return iface->show(s, it);
943 static const struct seq_operations sysvipc_proc_seqops = {
944 .start = sysvipc_proc_start,
945 .stop = sysvipc_proc_stop,
946 .next = sysvipc_proc_next,
947 .show = sysvipc_proc_show,
950 static int sysvipc_proc_open(struct inode *inode, struct file *file)
953 struct seq_file *seq;
954 struct ipc_proc_iter *iter;
957 iter = kmalloc(sizeof(*iter), GFP_KERNEL);
961 ret = seq_open(file, &sysvipc_proc_seqops);
965 seq = file->private_data;
968 iter->iface = PDE(inode)->data;
969 iter->ns = get_ipc_ns(current->nsproxy->ipc_ns);
977 static int sysvipc_proc_release(struct inode *inode, struct file *file)
979 struct seq_file *seq = file->private_data;
980 struct ipc_proc_iter *iter = seq->private;
981 put_ipc_ns(iter->ns);
982 return seq_release_private(inode, file);
985 static const struct file_operations sysvipc_proc_fops = {
986 .open = sysvipc_proc_open,
989 .release = sysvipc_proc_release,
991 #endif /* CONFIG_PROC_FS */