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![Manfred Spraul](/assets/img/avatar_default.png)
sysvipc_find_ipc() can be simplified further: - It uses a for() loop to locate the next entry in the idr. This can be replaced with idr_get_next(). - It receives two parameters (pos - which is actually an idr index and not a position, and new_pos, which is really a position). One parameter is sufficient. Link: https://lore.kernel.org/all/20210903052020.3265-3-manfred@colorfullife.com/ Link: https://lkml.kernel.org/r/20220805115733.104763-1-manfred@colorfullife.com Signed-off-by: Manfred Spraul <manfred@colorfullife.com> Acked-by: Davidlohr Bueso <dave@stgolabs.net> Acked-by: Waiman Long <longman@redhat.com> Cc: "Eric W . Biederman" <ebiederm@xmission.com> Cc: <1vier1@web.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
931 lines
24 KiB
C
931 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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WARN_ON_ONCE(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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*
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* The function determines the highest assigned index in @ids. It is intended
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* to be called when ids->max_idx needs to be updated.
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* Updating ids->max_idx is necessary when the current highest index ipc
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* object is deleted.
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* If no ipc object is allocated, then -1 is returned.
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*
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* ipc_ids.rwsem needs to be held by the caller.
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*/
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static int ipc_search_maxidx(struct ipc_ids *ids, int limit)
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{
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int tmpidx;
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int i;
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int retval;
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i = ilog2(limit+1);
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retval = 0;
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for (; i >= 0; i--) {
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tmpidx = retval | (1<<i);
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/*
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* "0" is a possible index value, thus search using
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* e.g. 15,7,3,1,0 instead of 16,8,4,2,1.
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*/
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tmpidx = tmpidx-1;
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if (idr_get_next(&ids->ipcs_idr, &tmpidx))
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retval |= (1<<i);
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}
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return retval - 1;
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}
|
|
|
|
/**
|
|
* 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);
|
|
|
|
WARN_ON_ONCE(idr_remove(&ids->ipcs_idr, idx) != ipcp);
|
|
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;
|
|
}
|
|
|
|
/**
|
|
* sysvipc_find_ipc - Find and lock the ipc structure based on seq pos
|
|
* @ids: ipc identifier set
|
|
* @pos: expected position
|
|
*
|
|
* The function finds an ipc structure, based on the sequence file
|
|
* position @pos. If there is no ipc structure at position @pos, then
|
|
* the successor is selected.
|
|
* If a structure is found, then it is locked (both rcu_read_lock() and
|
|
* ipc_lock_object()) and @pos is set to the position needed to locate
|
|
* the found ipc structure.
|
|
* If nothing is found (i.e. EOF), @pos is not modified.
|
|
*
|
|
* The function returns the found ipc structure, or NULL at EOF.
|
|
*/
|
|
static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t *pos)
|
|
{
|
|
int tmpidx;
|
|
struct kern_ipc_perm *ipc;
|
|
|
|
/* convert from position to idr index -> "-1" */
|
|
tmpidx = *pos - 1;
|
|
|
|
ipc = idr_get_next(&ids->ipcs_idr, &tmpidx);
|
|
if (ipc != NULL) {
|
|
rcu_read_lock();
|
|
ipc_lock_object(ipc);
|
|
|
|
/* convert from idr index to position -> "+1" */
|
|
*pos = tmpidx + 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);
|
|
|
|
/* Next -> search for *pos+1 */
|
|
(*pos)++;
|
|
return sysvipc_find_ipc(&iter->ns->ids[iface->ids], pos);
|
|
}
|
|
|
|
/*
|
|
* File positions: pos 0 -> header, pos n -> ipc idx = 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;
|
|
|
|
/* Otherwise return the correct ipc structure */
|
|
return sysvipc_find_ipc(ids, 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 */
|