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![Rafael Aquini](/assets/img/avatar_default.png)
sysvipc_find_ipc() was left with a costly way to check if the offset
position fed to it is bigger than the total number of IPC IDs in use. So
much so that the time it takes to iterate over /proc/sysvipc/* files grows
exponentially for a custom benchmark that creates "N" SYSV shm segments
and then times the read of /proc/sysvipc/shm (milliseconds):
12 msecs to read 1024 segs from /proc/sysvipc/shm
18 msecs to read 2048 segs from /proc/sysvipc/shm
65 msecs to read 4096 segs from /proc/sysvipc/shm
325 msecs to read 8192 segs from /proc/sysvipc/shm
1303 msecs to read 16384 segs from /proc/sysvipc/shm
5182 msecs to read 32768 segs from /proc/sysvipc/shm
The root problem lies with the loop that computes the total amount of ids
in use to check if the "pos" feeded to sysvipc_find_ipc() grew bigger than
"ids->in_use". That is a quite inneficient way to get to the maximum
index in the id lookup table, specially when that value is already
provided by struct ipc_ids.max_idx.
This patch follows up on the optimization introduced via commit
15df03c879
("sysvipc: make get_maxid O(1) again") and gets rid of the
aforementioned costly loop replacing it by a simpler checkpoint based on
ipc_get_maxidx() returned value, which allows for a smooth linear increase
in time complexity for the same custom benchmark:
2 msecs to read 1024 segs from /proc/sysvipc/shm
2 msecs to read 2048 segs from /proc/sysvipc/shm
4 msecs to read 4096 segs from /proc/sysvipc/shm
9 msecs to read 8192 segs from /proc/sysvipc/shm
19 msecs to read 16384 segs from /proc/sysvipc/shm
39 msecs to read 32768 segs from /proc/sysvipc/shm
Link: https://lkml.kernel.org/r/20210809203554.1562989-1-aquini@redhat.com
Signed-off-by: Rafael Aquini <aquini@redhat.com>
Acked-by: Davidlohr Bueso <dbueso@suse.de>
Acked-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Waiman Long <llong@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
920 lines
24 KiB
C
920 lines
24 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* linux/ipc/util.c
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* Copyright (C) 1992 Krishna Balasubramanian
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*
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* Sep 1997 - Call suser() last after "normal" permission checks so we
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* get BSD style process accounting right.
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* Occurs in several places in the IPC code.
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* Chris Evans, <chris@ferret.lmh.ox.ac.uk>
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* Nov 1999 - ipc helper functions, unified SMP locking
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* Manfred Spraul <manfred@colorfullife.com>
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* Oct 2002 - One lock per IPC id. RCU ipc_free for lock-free grow_ary().
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* Mingming Cao <cmm@us.ibm.com>
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* Mar 2006 - support for audit of ipc object properties
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* Dustin Kirkland <dustin.kirkland@us.ibm.com>
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* Jun 2006 - namespaces ssupport
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* OpenVZ, SWsoft Inc.
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* Pavel Emelianov <xemul@openvz.org>
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*
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* General sysv ipc locking scheme:
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* rcu_read_lock()
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* obtain the ipc object (kern_ipc_perm) by looking up the id in an idr
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* tree.
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* - perform initial checks (capabilities, auditing and permission,
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* etc).
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* - perform read-only operations, such as INFO command, that
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* do not demand atomicity
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* acquire the ipc lock (kern_ipc_perm.lock) through
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* ipc_lock_object()
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* - perform read-only operations that demand atomicity,
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* such as STAT command.
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* - perform data updates, such as SET, RMID commands and
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* mechanism-specific operations (semop/semtimedop,
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* msgsnd/msgrcv, shmat/shmdt).
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* drop the ipc lock, through ipc_unlock_object().
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* rcu_read_unlock()
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*
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* The ids->rwsem must be taken when:
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* - creating, removing and iterating the existing entries in ipc
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* identifier sets.
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* - iterating through files under /proc/sysvipc/
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*
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* Note that sems have a special fast path that avoids kern_ipc_perm.lock -
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* see sem_lock().
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*/
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#include <linux/mm.h>
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#include <linux/shm.h>
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#include <linux/init.h>
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#include <linux/msg.h>
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#include <linux/vmalloc.h>
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#include <linux/slab.h>
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#include <linux/notifier.h>
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#include <linux/capability.h>
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#include <linux/highuid.h>
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#include <linux/security.h>
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#include <linux/rcupdate.h>
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#include <linux/workqueue.h>
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#include <linux/seq_file.h>
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#include <linux/proc_fs.h>
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#include <linux/audit.h>
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#include <linux/nsproxy.h>
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#include <linux/rwsem.h>
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#include <linux/memory.h>
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#include <linux/ipc_namespace.h>
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#include <linux/rhashtable.h>
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#include <linux/log2.h>
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#include <asm/unistd.h>
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#include "util.h"
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struct ipc_proc_iface {
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const char *path;
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const char *header;
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int ids;
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int (*show)(struct seq_file *, void *);
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};
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/**
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* ipc_init - initialise ipc subsystem
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*
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* The various sysv ipc resources (semaphores, messages and shared
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* memory) are initialised.
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*
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* A callback routine is registered into the memory hotplug notifier
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* chain: since msgmni scales to lowmem this callback routine will be
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* called upon successful memory add / remove to recompute msmgni.
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*/
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static int __init ipc_init(void)
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{
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proc_mkdir("sysvipc", NULL);
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sem_init();
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msg_init();
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shm_init();
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return 0;
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}
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device_initcall(ipc_init);
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static const struct rhashtable_params ipc_kht_params = {
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.head_offset = offsetof(struct kern_ipc_perm, khtnode),
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.key_offset = offsetof(struct kern_ipc_perm, key),
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.key_len = sizeof_field(struct kern_ipc_perm, key),
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.automatic_shrinking = true,
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};
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/**
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* ipc_init_ids - initialise ipc identifiers
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* @ids: ipc identifier set
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*
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* Set up the sequence range to use for the ipc identifier range (limited
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* below ipc_mni) then initialise the keys hashtable and ids idr.
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*/
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void ipc_init_ids(struct ipc_ids *ids)
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{
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ids->in_use = 0;
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ids->seq = 0;
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init_rwsem(&ids->rwsem);
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rhashtable_init(&ids->key_ht, &ipc_kht_params);
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idr_init(&ids->ipcs_idr);
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ids->max_idx = -1;
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ids->last_idx = -1;
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#ifdef CONFIG_CHECKPOINT_RESTORE
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ids->next_id = -1;
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#endif
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}
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#ifdef CONFIG_PROC_FS
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static const struct proc_ops sysvipc_proc_ops;
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/**
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* ipc_init_proc_interface - create a proc interface for sysipc types using a seq_file interface.
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* @path: Path in procfs
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* @header: Banner to be printed at the beginning of the file.
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* @ids: ipc id table to iterate.
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* @show: show routine.
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*/
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void __init ipc_init_proc_interface(const char *path, const char *header,
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int ids, int (*show)(struct seq_file *, void *))
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{
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struct proc_dir_entry *pde;
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struct ipc_proc_iface *iface;
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iface = kmalloc(sizeof(*iface), GFP_KERNEL);
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if (!iface)
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return;
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iface->path = path;
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iface->header = header;
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iface->ids = ids;
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iface->show = show;
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pde = proc_create_data(path,
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S_IRUGO, /* world readable */
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NULL, /* parent dir */
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&sysvipc_proc_ops,
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iface);
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if (!pde)
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kfree(iface);
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}
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#endif
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/**
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* ipc_findkey - find a key in an ipc identifier set
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* @ids: ipc identifier set
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* @key: key to find
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*
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* Returns the locked pointer to the ipc structure if found or NULL
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* otherwise. If key is found ipc points to the owning ipc structure
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*
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* Called with writer ipc_ids.rwsem held.
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*/
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static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key)
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{
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struct kern_ipc_perm *ipcp;
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ipcp = rhashtable_lookup_fast(&ids->key_ht, &key,
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ipc_kht_params);
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if (!ipcp)
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return NULL;
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rcu_read_lock();
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ipc_lock_object(ipcp);
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return ipcp;
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}
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/*
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* Insert new IPC object into idr tree, and set sequence number and id
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* in the correct order.
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* Especially:
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* - the sequence number must be set before inserting the object into the idr,
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* because the sequence number is accessed without a lock.
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* - the id can/must be set after inserting the object into the idr.
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* All accesses must be done after getting kern_ipc_perm.lock.
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*
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* The caller must own kern_ipc_perm.lock.of the new object.
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* On error, the function returns a (negative) error code.
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*
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* To conserve sequence number space, especially with extended ipc_mni,
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* the sequence number is incremented only when the returned ID is less than
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* the last one.
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*/
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static inline int ipc_idr_alloc(struct ipc_ids *ids, struct kern_ipc_perm *new)
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{
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int idx, next_id = -1;
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#ifdef CONFIG_CHECKPOINT_RESTORE
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next_id = ids->next_id;
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ids->next_id = -1;
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#endif
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/*
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* As soon as a new object is inserted into the idr,
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* ipc_obtain_object_idr() or ipc_obtain_object_check() can find it,
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* and the lockless preparations for ipc operations can start.
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* This means especially: permission checks, audit calls, allocation
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* of undo structures, ...
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*
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* Thus the object must be fully initialized, and if something fails,
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* then the full tear-down sequence must be followed.
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* (i.e.: set new->deleted, reduce refcount, call_rcu())
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*/
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if (next_id < 0) { /* !CHECKPOINT_RESTORE or next_id is unset */
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int max_idx;
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max_idx = max(ids->in_use*3/2, ipc_min_cycle);
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max_idx = min(max_idx, ipc_mni);
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/* allocate the idx, with a NULL struct kern_ipc_perm */
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idx = idr_alloc_cyclic(&ids->ipcs_idr, NULL, 0, max_idx,
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GFP_NOWAIT);
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if (idx >= 0) {
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/*
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* idx got allocated successfully.
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* Now calculate the sequence number and set the
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* pointer for real.
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*/
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if (idx <= ids->last_idx) {
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ids->seq++;
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if (ids->seq >= ipcid_seq_max())
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ids->seq = 0;
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}
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ids->last_idx = idx;
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new->seq = ids->seq;
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/* no need for smp_wmb(), this is done
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* inside idr_replace, as part of
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* rcu_assign_pointer
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*/
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idr_replace(&ids->ipcs_idr, new, idx);
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}
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} else {
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new->seq = ipcid_to_seqx(next_id);
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idx = idr_alloc(&ids->ipcs_idr, new, ipcid_to_idx(next_id),
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0, GFP_NOWAIT);
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}
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if (idx >= 0)
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new->id = (new->seq << ipcmni_seq_shift()) + idx;
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return idx;
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}
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/**
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* ipc_addid - add an ipc identifier
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* @ids: ipc identifier set
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* @new: new ipc permission set
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* @limit: limit for the number of used ids
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*
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* Add an entry 'new' to the ipc ids idr. The permissions object is
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* initialised and the first free entry is set up and the index assigned
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* is returned. The 'new' entry is returned in a locked state on success.
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*
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* On failure the entry is not locked and a negative err-code is returned.
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* The caller must use ipc_rcu_putref() to free the identifier.
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*
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* Called with writer ipc_ids.rwsem held.
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*/
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int ipc_addid(struct ipc_ids *ids, struct kern_ipc_perm *new, int limit)
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{
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kuid_t euid;
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kgid_t egid;
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int idx, err;
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/* 1) Initialize the refcount so that ipc_rcu_putref works */
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refcount_set(&new->refcount, 1);
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if (limit > ipc_mni)
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limit = ipc_mni;
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if (ids->in_use >= limit)
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return -ENOSPC;
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idr_preload(GFP_KERNEL);
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spin_lock_init(&new->lock);
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rcu_read_lock();
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spin_lock(&new->lock);
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current_euid_egid(&euid, &egid);
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new->cuid = new->uid = euid;
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new->gid = new->cgid = egid;
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new->deleted = false;
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idx = ipc_idr_alloc(ids, new);
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idr_preload_end();
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if (idx >= 0 && new->key != IPC_PRIVATE) {
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err = rhashtable_insert_fast(&ids->key_ht, &new->khtnode,
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ipc_kht_params);
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if (err < 0) {
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idr_remove(&ids->ipcs_idr, idx);
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idx = err;
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}
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}
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if (idx < 0) {
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new->deleted = true;
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spin_unlock(&new->lock);
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rcu_read_unlock();
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return idx;
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}
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ids->in_use++;
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if (idx > ids->max_idx)
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ids->max_idx = idx;
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return idx;
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}
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/**
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* ipcget_new - create a new ipc object
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* @ns: ipc namespace
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* @ids: ipc identifier set
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* @ops: the actual creation routine to call
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* @params: its parameters
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*
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* This routine is called by sys_msgget, sys_semget() and sys_shmget()
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* when the key is IPC_PRIVATE.
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*/
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static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
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const struct ipc_ops *ops, struct ipc_params *params)
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{
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int err;
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down_write(&ids->rwsem);
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err = ops->getnew(ns, params);
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up_write(&ids->rwsem);
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return err;
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}
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/**
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* ipc_check_perms - check security and permissions for an ipc object
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* @ns: ipc namespace
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* @ipcp: ipc permission set
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* @ops: the actual security routine to call
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* @params: its parameters
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*
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* This routine is called by sys_msgget(), sys_semget() and sys_shmget()
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* when the key is not IPC_PRIVATE and that key already exists in the
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* ds IDR.
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*
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* On success, the ipc id is returned.
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*
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* It is called with ipc_ids.rwsem and ipcp->lock held.
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*/
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static int ipc_check_perms(struct ipc_namespace *ns,
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struct kern_ipc_perm *ipcp,
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const struct ipc_ops *ops,
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struct ipc_params *params)
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{
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int err;
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if (ipcperms(ns, ipcp, params->flg))
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err = -EACCES;
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else {
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err = ops->associate(ipcp, params->flg);
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if (!err)
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err = ipcp->id;
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}
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return err;
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}
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/**
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* ipcget_public - get an ipc object or create a new one
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* @ns: ipc namespace
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* @ids: ipc identifier set
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* @ops: the actual creation routine to call
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* @params: its parameters
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*
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* This routine is called by sys_msgget, sys_semget() and sys_shmget()
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* when the key is not IPC_PRIVATE.
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* It adds a new entry if the key is not found and does some permission
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* / security checkings if the key is found.
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*
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* On success, the ipc id is returned.
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*/
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static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
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const struct ipc_ops *ops, struct ipc_params *params)
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{
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struct kern_ipc_perm *ipcp;
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int flg = params->flg;
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int err;
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/*
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* Take the lock as a writer since we are potentially going to add
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* a new entry + read locks are not "upgradable"
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*/
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down_write(&ids->rwsem);
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ipcp = ipc_findkey(ids, params->key);
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if (ipcp == NULL) {
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/* key not used */
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if (!(flg & IPC_CREAT))
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err = -ENOENT;
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else
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err = ops->getnew(ns, params);
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} else {
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/* ipc object has been locked by ipc_findkey() */
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if (flg & IPC_CREAT && flg & IPC_EXCL)
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err = -EEXIST;
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else {
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err = 0;
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if (ops->more_checks)
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err = ops->more_checks(ipcp, params);
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if (!err)
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/*
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* ipc_check_perms returns the IPC id on
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* success
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*/
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err = ipc_check_perms(ns, ipcp, ops, params);
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}
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ipc_unlock(ipcp);
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}
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up_write(&ids->rwsem);
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return err;
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}
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/**
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* ipc_kht_remove - remove an ipc from the key hashtable
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* @ids: ipc identifier set
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* @ipcp: ipc perm structure containing the key to remove
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*
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* ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
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* before this function is called, and remain locked on the exit.
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*/
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static void ipc_kht_remove(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
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{
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if (ipcp->key != IPC_PRIVATE)
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rhashtable_remove_fast(&ids->key_ht, &ipcp->khtnode,
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ipc_kht_params);
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}
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/**
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* ipc_search_maxidx - search for the highest assigned index
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* @ids: ipc identifier set
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* @limit: known upper limit for highest assigned index
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*
|
|
* The function determines the highest assigned index in @ids. It is intended
|
|
* to be called when ids->max_idx needs to be updated.
|
|
* Updating ids->max_idx is necessary when the current highest index ipc
|
|
* object is deleted.
|
|
* If no ipc object is allocated, then -1 is returned.
|
|
*
|
|
* ipc_ids.rwsem needs to be held by the caller.
|
|
*/
|
|
static int ipc_search_maxidx(struct ipc_ids *ids, int limit)
|
|
{
|
|
int tmpidx;
|
|
int i;
|
|
int retval;
|
|
|
|
i = ilog2(limit+1);
|
|
|
|
retval = 0;
|
|
for (; i >= 0; i--) {
|
|
tmpidx = retval | (1<<i);
|
|
/*
|
|
* "0" is a possible index value, thus search using
|
|
* e.g. 15,7,3,1,0 instead of 16,8,4,2,1.
|
|
*/
|
|
tmpidx = tmpidx-1;
|
|
if (idr_get_next(&ids->ipcs_idr, &tmpidx))
|
|
retval |= (1<<i);
|
|
}
|
|
return retval - 1;
|
|
}
|
|
|
|
/**
|
|
* ipc_rmid - remove an ipc identifier
|
|
* @ids: ipc identifier set
|
|
* @ipcp: ipc perm structure containing the identifier to remove
|
|
*
|
|
* ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
|
|
* before this function is called, and remain locked on the exit.
|
|
*/
|
|
void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
|
|
{
|
|
int idx = ipcid_to_idx(ipcp->id);
|
|
|
|
idr_remove(&ids->ipcs_idr, idx);
|
|
ipc_kht_remove(ids, ipcp);
|
|
ids->in_use--;
|
|
ipcp->deleted = true;
|
|
|
|
if (unlikely(idx == ids->max_idx)) {
|
|
idx = ids->max_idx-1;
|
|
if (idx >= 0)
|
|
idx = ipc_search_maxidx(ids, idx);
|
|
ids->max_idx = idx;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* ipc_set_key_private - switch the key of an existing ipc to IPC_PRIVATE
|
|
* @ids: ipc identifier set
|
|
* @ipcp: ipc perm structure containing the key to modify
|
|
*
|
|
* ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
|
|
* before this function is called, and remain locked on the exit.
|
|
*/
|
|
void ipc_set_key_private(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
|
|
{
|
|
ipc_kht_remove(ids, ipcp);
|
|
ipcp->key = IPC_PRIVATE;
|
|
}
|
|
|
|
bool ipc_rcu_getref(struct kern_ipc_perm *ptr)
|
|
{
|
|
return refcount_inc_not_zero(&ptr->refcount);
|
|
}
|
|
|
|
void ipc_rcu_putref(struct kern_ipc_perm *ptr,
|
|
void (*func)(struct rcu_head *head))
|
|
{
|
|
if (!refcount_dec_and_test(&ptr->refcount))
|
|
return;
|
|
|
|
call_rcu(&ptr->rcu, func);
|
|
}
|
|
|
|
/**
|
|
* ipcperms - check ipc permissions
|
|
* @ns: ipc namespace
|
|
* @ipcp: ipc permission set
|
|
* @flag: desired permission set
|
|
*
|
|
* Check user, group, other permissions for access
|
|
* to ipc resources. return 0 if allowed
|
|
*
|
|
* @flag will most probably be 0 or ``S_...UGO`` from <linux/stat.h>
|
|
*/
|
|
int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flag)
|
|
{
|
|
kuid_t euid = current_euid();
|
|
int requested_mode, granted_mode;
|
|
|
|
audit_ipc_obj(ipcp);
|
|
requested_mode = (flag >> 6) | (flag >> 3) | flag;
|
|
granted_mode = ipcp->mode;
|
|
if (uid_eq(euid, ipcp->cuid) ||
|
|
uid_eq(euid, ipcp->uid))
|
|
granted_mode >>= 6;
|
|
else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid))
|
|
granted_mode >>= 3;
|
|
/* is there some bit set in requested_mode but not in granted_mode? */
|
|
if ((requested_mode & ~granted_mode & 0007) &&
|
|
!ns_capable(ns->user_ns, CAP_IPC_OWNER))
|
|
return -1;
|
|
|
|
return security_ipc_permission(ipcp, flag);
|
|
}
|
|
|
|
/*
|
|
* Functions to convert between the kern_ipc_perm structure and the
|
|
* old/new ipc_perm structures
|
|
*/
|
|
|
|
/**
|
|
* kernel_to_ipc64_perm - convert kernel ipc permissions to user
|
|
* @in: kernel permissions
|
|
* @out: new style ipc permissions
|
|
*
|
|
* Turn the kernel object @in into a set of permissions descriptions
|
|
* for returning to userspace (@out).
|
|
*/
|
|
void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out)
|
|
{
|
|
out->key = in->key;
|
|
out->uid = from_kuid_munged(current_user_ns(), in->uid);
|
|
out->gid = from_kgid_munged(current_user_ns(), in->gid);
|
|
out->cuid = from_kuid_munged(current_user_ns(), in->cuid);
|
|
out->cgid = from_kgid_munged(current_user_ns(), in->cgid);
|
|
out->mode = in->mode;
|
|
out->seq = in->seq;
|
|
}
|
|
|
|
/**
|
|
* ipc64_perm_to_ipc_perm - convert new ipc permissions to old
|
|
* @in: new style ipc permissions
|
|
* @out: old style ipc permissions
|
|
*
|
|
* Turn the new style permissions object @in into a compatibility
|
|
* object and store it into the @out pointer.
|
|
*/
|
|
void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out)
|
|
{
|
|
out->key = in->key;
|
|
SET_UID(out->uid, in->uid);
|
|
SET_GID(out->gid, in->gid);
|
|
SET_UID(out->cuid, in->cuid);
|
|
SET_GID(out->cgid, in->cgid);
|
|
out->mode = in->mode;
|
|
out->seq = in->seq;
|
|
}
|
|
|
|
/**
|
|
* ipc_obtain_object_idr
|
|
* @ids: ipc identifier set
|
|
* @id: ipc id to look for
|
|
*
|
|
* Look for an id in the ipc ids idr and return associated ipc object.
|
|
*
|
|
* Call inside the RCU critical section.
|
|
* The ipc object is *not* locked on exit.
|
|
*/
|
|
struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id)
|
|
{
|
|
struct kern_ipc_perm *out;
|
|
int idx = ipcid_to_idx(id);
|
|
|
|
out = idr_find(&ids->ipcs_idr, idx);
|
|
if (!out)
|
|
return ERR_PTR(-EINVAL);
|
|
|
|
return out;
|
|
}
|
|
|
|
/**
|
|
* ipc_obtain_object_check
|
|
* @ids: ipc identifier set
|
|
* @id: ipc id to look for
|
|
*
|
|
* Similar to ipc_obtain_object_idr() but also checks the ipc object
|
|
* sequence number.
|
|
*
|
|
* Call inside the RCU critical section.
|
|
* The ipc object is *not* locked on exit.
|
|
*/
|
|
struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id)
|
|
{
|
|
struct kern_ipc_perm *out = ipc_obtain_object_idr(ids, id);
|
|
|
|
if (IS_ERR(out))
|
|
goto out;
|
|
|
|
if (ipc_checkid(out, id))
|
|
return ERR_PTR(-EINVAL);
|
|
out:
|
|
return out;
|
|
}
|
|
|
|
/**
|
|
* ipcget - Common sys_*get() code
|
|
* @ns: namespace
|
|
* @ids: ipc identifier set
|
|
* @ops: operations to be called on ipc object creation, permission checks
|
|
* and further checks
|
|
* @params: the parameters needed by the previous operations.
|
|
*
|
|
* Common routine called by sys_msgget(), sys_semget() and sys_shmget().
|
|
*/
|
|
int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
|
|
const struct ipc_ops *ops, struct ipc_params *params)
|
|
{
|
|
if (params->key == IPC_PRIVATE)
|
|
return ipcget_new(ns, ids, ops, params);
|
|
else
|
|
return ipcget_public(ns, ids, ops, params);
|
|
}
|
|
|
|
/**
|
|
* ipc_update_perm - update the permissions of an ipc object
|
|
* @in: the permission given as input.
|
|
* @out: the permission of the ipc to set.
|
|
*/
|
|
int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out)
|
|
{
|
|
kuid_t uid = make_kuid(current_user_ns(), in->uid);
|
|
kgid_t gid = make_kgid(current_user_ns(), in->gid);
|
|
if (!uid_valid(uid) || !gid_valid(gid))
|
|
return -EINVAL;
|
|
|
|
out->uid = uid;
|
|
out->gid = gid;
|
|
out->mode = (out->mode & ~S_IRWXUGO)
|
|
| (in->mode & S_IRWXUGO);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* ipcctl_obtain_check - retrieve an ipc object and check permissions
|
|
* @ns: ipc namespace
|
|
* @ids: the table of ids where to look for the ipc
|
|
* @id: the id of the ipc to retrieve
|
|
* @cmd: the cmd to check
|
|
* @perm: the permission to set
|
|
* @extra_perm: one extra permission parameter used by msq
|
|
*
|
|
* This function does some common audit and permissions check for some IPC_XXX
|
|
* cmd and is called from semctl_down, shmctl_down and msgctl_down.
|
|
*
|
|
* It:
|
|
* - retrieves the ipc object with the given id in the given table.
|
|
* - performs some audit and permission check, depending on the given cmd
|
|
* - returns a pointer to the ipc object or otherwise, the corresponding
|
|
* error.
|
|
*
|
|
* Call holding the both the rwsem and the rcu read lock.
|
|
*/
|
|
struct kern_ipc_perm *ipcctl_obtain_check(struct ipc_namespace *ns,
|
|
struct ipc_ids *ids, int id, int cmd,
|
|
struct ipc64_perm *perm, int extra_perm)
|
|
{
|
|
kuid_t euid;
|
|
int err = -EPERM;
|
|
struct kern_ipc_perm *ipcp;
|
|
|
|
ipcp = ipc_obtain_object_check(ids, id);
|
|
if (IS_ERR(ipcp)) {
|
|
err = PTR_ERR(ipcp);
|
|
goto err;
|
|
}
|
|
|
|
audit_ipc_obj(ipcp);
|
|
if (cmd == IPC_SET)
|
|
audit_ipc_set_perm(extra_perm, perm->uid,
|
|
perm->gid, perm->mode);
|
|
|
|
euid = current_euid();
|
|
if (uid_eq(euid, ipcp->cuid) || uid_eq(euid, ipcp->uid) ||
|
|
ns_capable(ns->user_ns, CAP_SYS_ADMIN))
|
|
return ipcp; /* successful lookup */
|
|
err:
|
|
return ERR_PTR(err);
|
|
}
|
|
|
|
#ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
|
|
|
|
|
|
/**
|
|
* ipc_parse_version - ipc call version
|
|
* @cmd: pointer to command
|
|
*
|
|
* Return IPC_64 for new style IPC and IPC_OLD for old style IPC.
|
|
* The @cmd value is turned from an encoding command and version into
|
|
* just the command code.
|
|
*/
|
|
int ipc_parse_version(int *cmd)
|
|
{
|
|
if (*cmd & IPC_64) {
|
|
*cmd ^= IPC_64;
|
|
return IPC_64;
|
|
} else {
|
|
return IPC_OLD;
|
|
}
|
|
}
|
|
|
|
#endif /* CONFIG_ARCH_WANT_IPC_PARSE_VERSION */
|
|
|
|
#ifdef CONFIG_PROC_FS
|
|
struct ipc_proc_iter {
|
|
struct ipc_namespace *ns;
|
|
struct pid_namespace *pid_ns;
|
|
struct ipc_proc_iface *iface;
|
|
};
|
|
|
|
struct pid_namespace *ipc_seq_pid_ns(struct seq_file *s)
|
|
{
|
|
struct ipc_proc_iter *iter = s->private;
|
|
return iter->pid_ns;
|
|
}
|
|
|
|
/*
|
|
* This routine locks the ipc structure found at least at position pos.
|
|
*/
|
|
static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos,
|
|
loff_t *new_pos)
|
|
{
|
|
struct kern_ipc_perm *ipc = NULL;
|
|
int max_idx = ipc_get_maxidx(ids);
|
|
|
|
if (max_idx == -1 || pos > max_idx)
|
|
goto out;
|
|
|
|
for (; pos <= max_idx; pos++) {
|
|
ipc = idr_find(&ids->ipcs_idr, pos);
|
|
if (ipc != NULL) {
|
|
rcu_read_lock();
|
|
ipc_lock_object(ipc);
|
|
break;
|
|
}
|
|
}
|
|
out:
|
|
*new_pos = pos + 1;
|
|
return ipc;
|
|
}
|
|
|
|
static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
|
|
{
|
|
struct ipc_proc_iter *iter = s->private;
|
|
struct ipc_proc_iface *iface = iter->iface;
|
|
struct kern_ipc_perm *ipc = it;
|
|
|
|
/* If we had an ipc id locked before, unlock it */
|
|
if (ipc && ipc != SEQ_START_TOKEN)
|
|
ipc_unlock(ipc);
|
|
|
|
return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos);
|
|
}
|
|
|
|
/*
|
|
* File positions: pos 0 -> header, pos n -> ipc id = n - 1.
|
|
* SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START.
|
|
*/
|
|
static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
|
|
{
|
|
struct ipc_proc_iter *iter = s->private;
|
|
struct ipc_proc_iface *iface = iter->iface;
|
|
struct ipc_ids *ids;
|
|
|
|
ids = &iter->ns->ids[iface->ids];
|
|
|
|
/*
|
|
* Take the lock - this will be released by the corresponding
|
|
* call to stop().
|
|
*/
|
|
down_read(&ids->rwsem);
|
|
|
|
/* pos < 0 is invalid */
|
|
if (*pos < 0)
|
|
return NULL;
|
|
|
|
/* pos == 0 means header */
|
|
if (*pos == 0)
|
|
return SEQ_START_TOKEN;
|
|
|
|
/* Find the (pos-1)th ipc */
|
|
return sysvipc_find_ipc(ids, *pos - 1, pos);
|
|
}
|
|
|
|
static void sysvipc_proc_stop(struct seq_file *s, void *it)
|
|
{
|
|
struct kern_ipc_perm *ipc = it;
|
|
struct ipc_proc_iter *iter = s->private;
|
|
struct ipc_proc_iface *iface = iter->iface;
|
|
struct ipc_ids *ids;
|
|
|
|
/* If we had a locked structure, release it */
|
|
if (ipc && ipc != SEQ_START_TOKEN)
|
|
ipc_unlock(ipc);
|
|
|
|
ids = &iter->ns->ids[iface->ids];
|
|
/* Release the lock we took in start() */
|
|
up_read(&ids->rwsem);
|
|
}
|
|
|
|
static int sysvipc_proc_show(struct seq_file *s, void *it)
|
|
{
|
|
struct ipc_proc_iter *iter = s->private;
|
|
struct ipc_proc_iface *iface = iter->iface;
|
|
|
|
if (it == SEQ_START_TOKEN) {
|
|
seq_puts(s, iface->header);
|
|
return 0;
|
|
}
|
|
|
|
return iface->show(s, it);
|
|
}
|
|
|
|
static const struct seq_operations sysvipc_proc_seqops = {
|
|
.start = sysvipc_proc_start,
|
|
.stop = sysvipc_proc_stop,
|
|
.next = sysvipc_proc_next,
|
|
.show = sysvipc_proc_show,
|
|
};
|
|
|
|
static int sysvipc_proc_open(struct inode *inode, struct file *file)
|
|
{
|
|
struct ipc_proc_iter *iter;
|
|
|
|
iter = __seq_open_private(file, &sysvipc_proc_seqops, sizeof(*iter));
|
|
if (!iter)
|
|
return -ENOMEM;
|
|
|
|
iter->iface = PDE_DATA(inode);
|
|
iter->ns = get_ipc_ns(current->nsproxy->ipc_ns);
|
|
iter->pid_ns = get_pid_ns(task_active_pid_ns(current));
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int sysvipc_proc_release(struct inode *inode, struct file *file)
|
|
{
|
|
struct seq_file *seq = file->private_data;
|
|
struct ipc_proc_iter *iter = seq->private;
|
|
put_ipc_ns(iter->ns);
|
|
put_pid_ns(iter->pid_ns);
|
|
return seq_release_private(inode, file);
|
|
}
|
|
|
|
static const struct proc_ops sysvipc_proc_ops = {
|
|
.proc_flags = PROC_ENTRY_PERMANENT,
|
|
.proc_open = sysvipc_proc_open,
|
|
.proc_read = seq_read,
|
|
.proc_lseek = seq_lseek,
|
|
.proc_release = sysvipc_proc_release,
|
|
};
|
|
#endif /* CONFIG_PROC_FS */
|