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![Christian Kujau](/assets/img/avatar_default.png)
I tried to send the forcedeth maintainer an email, but it came back with: "The mail address manfreds@colorfullife.com is not read anymore. Please resent your mail to manfred@ instead of manfreds@." This patch fixes this. Signed-off-by: Adrian Bunk <bunk@stusta.de>
738 lines
17 KiB
C
738 lines
17 KiB
C
/*
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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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*/
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#include <linux/config.h>
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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/smp_lock.h>
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#include <linux/vmalloc.h>
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#include <linux/slab.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 <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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struct ipc_ids *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 system5 IPC resources (semaphores, messages and shared
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* memory are initialised
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*/
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static int __init ipc_init(void)
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{
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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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__initcall(ipc_init);
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/**
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* ipc_init_ids - initialise IPC identifiers
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* @ids: Identifier set
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* @size: Number of identifiers
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*
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* Given a size for the ipc identifier range (limited below IPCMNI)
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* set up the sequence range to use then allocate and initialise the
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* array itself.
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*/
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void __init ipc_init_ids(struct ipc_ids* ids, int size)
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{
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int i;
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sema_init(&ids->sem,1);
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if(size > IPCMNI)
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size = IPCMNI;
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ids->in_use = 0;
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ids->max_id = -1;
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ids->seq = 0;
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{
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int seq_limit = INT_MAX/SEQ_MULTIPLIER;
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if(seq_limit > USHRT_MAX)
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ids->seq_max = USHRT_MAX;
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else
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ids->seq_max = seq_limit;
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}
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ids->entries = ipc_rcu_alloc(sizeof(struct kern_ipc_perm *)*size +
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sizeof(struct ipc_id_ary));
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if(ids->entries == NULL) {
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printk(KERN_ERR "ipc_init_ids() failed, ipc service disabled.\n");
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size = 0;
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ids->entries = &ids->nullentry;
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}
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ids->entries->size = size;
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for(i=0;i<size;i++)
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ids->entries->p[i] = NULL;
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}
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#ifdef CONFIG_PROC_FS
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static struct file_operations sysvipc_proc_fops;
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/**
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* ipc_init_proc_interface - Create a proc interface for sysipc types
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* 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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struct ipc_ids *ids,
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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 = create_proc_entry(path,
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S_IRUGO, /* world readable */
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NULL /* parent dir */);
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if (pde) {
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pde->data = iface;
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pde->proc_fops = &sysvipc_proc_fops;
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} else {
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kfree(iface);
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}
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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: Identifier set
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* @key: The key to find
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*
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* Requires ipc_ids.sem locked.
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* Returns the identifier if found or -1 if not.
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*/
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int ipc_findkey(struct ipc_ids* ids, key_t key)
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{
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int id;
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struct kern_ipc_perm* p;
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int max_id = ids->max_id;
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/*
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* rcu_dereference() is not needed here
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* since ipc_ids.sem is held
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*/
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for (id = 0; id <= max_id; id++) {
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p = ids->entries->p[id];
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if(p==NULL)
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continue;
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if (key == p->key)
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return id;
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}
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return -1;
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}
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/*
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* Requires ipc_ids.sem locked
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*/
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static int grow_ary(struct ipc_ids* ids, int newsize)
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{
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struct ipc_id_ary* new;
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struct ipc_id_ary* old;
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int i;
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int size = ids->entries->size;
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if(newsize > IPCMNI)
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newsize = IPCMNI;
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if(newsize <= size)
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return newsize;
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new = ipc_rcu_alloc(sizeof(struct kern_ipc_perm *)*newsize +
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sizeof(struct ipc_id_ary));
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if(new == NULL)
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return size;
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new->size = newsize;
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memcpy(new->p, ids->entries->p, sizeof(struct kern_ipc_perm *)*size +
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sizeof(struct ipc_id_ary));
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for(i=size;i<newsize;i++) {
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new->p[i] = NULL;
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}
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old = ids->entries;
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/*
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* Use rcu_assign_pointer() to make sure the memcpyed contents
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* of the new array are visible before the new array becomes visible.
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*/
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rcu_assign_pointer(ids->entries, new);
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ipc_rcu_putref(old);
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return newsize;
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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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* @size: new size limit for the id array
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*
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* Add an entry 'new' to the IPC arrays. The permissions object is
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* initialised and the first free entry is set up and the id assigned
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* is returned. The list is returned in a locked state on success.
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* On failure the list is not locked and -1 is returned.
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*
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* Called with ipc_ids.sem held.
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*/
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int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
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{
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int id;
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size = grow_ary(ids,size);
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/*
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* rcu_dereference()() is not needed here since
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* ipc_ids.sem is held
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*/
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for (id = 0; id < size; id++) {
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if(ids->entries->p[id] == NULL)
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goto found;
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}
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return -1;
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found:
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ids->in_use++;
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if (id > ids->max_id)
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ids->max_id = id;
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new->cuid = new->uid = current->euid;
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new->gid = new->cgid = current->egid;
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new->seq = ids->seq++;
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if(ids->seq > ids->seq_max)
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ids->seq = 0;
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spin_lock_init(&new->lock);
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new->deleted = 0;
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rcu_read_lock();
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spin_lock(&new->lock);
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ids->entries->p[id] = new;
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return id;
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}
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/**
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* ipc_rmid - remove an IPC identifier
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* @ids: identifier set
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* @id: Identifier to remove
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*
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* The identifier must be valid, and in use. The kernel will panic if
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* fed an invalid identifier. The entry is removed and internal
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* variables recomputed. The object associated with the identifier
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* is returned.
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* ipc_ids.sem and the spinlock for this ID is hold before this function
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* is called, and remain locked on the exit.
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*/
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struct kern_ipc_perm* ipc_rmid(struct ipc_ids* ids, int id)
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{
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struct kern_ipc_perm* p;
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int lid = id % SEQ_MULTIPLIER;
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if(lid >= ids->entries->size)
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BUG();
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/*
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* do not need a rcu_dereference()() here to force ordering
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* on Alpha, since the ipc_ids.sem is held.
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*/
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p = ids->entries->p[lid];
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ids->entries->p[lid] = NULL;
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if(p==NULL)
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BUG();
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ids->in_use--;
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if (lid == ids->max_id) {
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do {
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lid--;
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if(lid == -1)
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break;
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} while (ids->entries->p[lid] == NULL);
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ids->max_id = lid;
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}
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p->deleted = 1;
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return p;
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}
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/**
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* ipc_alloc - allocate ipc space
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* @size: size desired
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*
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* Allocate memory from the appropriate pools and return a pointer to it.
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* NULL is returned if the allocation fails
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*/
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void* ipc_alloc(int size)
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{
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void* out;
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if(size > PAGE_SIZE)
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out = vmalloc(size);
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else
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out = kmalloc(size, GFP_KERNEL);
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return out;
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}
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/**
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* ipc_free - free ipc space
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* @ptr: pointer returned by ipc_alloc
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* @size: size of block
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*
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* Free a block created with ipc_alloc. The caller must know the size
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* used in the allocation call.
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*/
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void ipc_free(void* ptr, int size)
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{
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if(size > PAGE_SIZE)
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vfree(ptr);
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else
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kfree(ptr);
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}
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/*
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* rcu allocations:
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* There are three headers that are prepended to the actual allocation:
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* - during use: ipc_rcu_hdr.
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* - during the rcu grace period: ipc_rcu_grace.
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* - [only if vmalloc]: ipc_rcu_sched.
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* Their lifetime doesn't overlap, thus the headers share the same memory.
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* Unlike a normal union, they are right-aligned, thus some container_of
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* forward/backward casting is necessary:
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*/
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struct ipc_rcu_hdr
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{
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int refcount;
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int is_vmalloc;
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void *data[0];
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};
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struct ipc_rcu_grace
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{
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struct rcu_head rcu;
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/* "void *" makes sure alignment of following data is sane. */
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void *data[0];
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};
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struct ipc_rcu_sched
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{
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struct work_struct work;
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/* "void *" makes sure alignment of following data is sane. */
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void *data[0];
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};
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#define HDRLEN_KMALLOC (sizeof(struct ipc_rcu_grace) > sizeof(struct ipc_rcu_hdr) ? \
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sizeof(struct ipc_rcu_grace) : sizeof(struct ipc_rcu_hdr))
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#define HDRLEN_VMALLOC (sizeof(struct ipc_rcu_sched) > HDRLEN_KMALLOC ? \
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sizeof(struct ipc_rcu_sched) : HDRLEN_KMALLOC)
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static inline int rcu_use_vmalloc(int size)
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{
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/* Too big for a single page? */
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if (HDRLEN_KMALLOC + size > PAGE_SIZE)
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return 1;
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return 0;
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}
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/**
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* ipc_rcu_alloc - allocate ipc and rcu space
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* @size: size desired
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*
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* Allocate memory for the rcu header structure + the object.
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* Returns the pointer to the object.
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* NULL is returned if the allocation fails.
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*/
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void* ipc_rcu_alloc(int size)
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{
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void* out;
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/*
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* We prepend the allocation with the rcu struct, and
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* workqueue if necessary (for vmalloc).
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*/
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if (rcu_use_vmalloc(size)) {
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out = vmalloc(HDRLEN_VMALLOC + size);
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if (out) {
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out += HDRLEN_VMALLOC;
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container_of(out, struct ipc_rcu_hdr, data)->is_vmalloc = 1;
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container_of(out, struct ipc_rcu_hdr, data)->refcount = 1;
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}
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} else {
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out = kmalloc(HDRLEN_KMALLOC + size, GFP_KERNEL);
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if (out) {
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out += HDRLEN_KMALLOC;
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container_of(out, struct ipc_rcu_hdr, data)->is_vmalloc = 0;
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container_of(out, struct ipc_rcu_hdr, data)->refcount = 1;
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}
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}
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return out;
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}
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void ipc_rcu_getref(void *ptr)
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{
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container_of(ptr, struct ipc_rcu_hdr, data)->refcount++;
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}
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/**
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* ipc_schedule_free - free ipc + rcu space
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* @head: RCU callback structure for queued work
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*
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* Since RCU callback function is called in bh,
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* we need to defer the vfree to schedule_work
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*/
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static void ipc_schedule_free(struct rcu_head *head)
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{
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struct ipc_rcu_grace *grace =
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container_of(head, struct ipc_rcu_grace, rcu);
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struct ipc_rcu_sched *sched =
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container_of(&(grace->data[0]), struct ipc_rcu_sched, data[0]);
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INIT_WORK(&sched->work, vfree, sched);
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schedule_work(&sched->work);
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}
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/**
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* ipc_immediate_free - free ipc + rcu space
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* @head: RCU callback structure that contains pointer to be freed
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*
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* Free from the RCU callback context
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*/
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static void ipc_immediate_free(struct rcu_head *head)
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{
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struct ipc_rcu_grace *free =
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container_of(head, struct ipc_rcu_grace, rcu);
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kfree(free);
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}
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void ipc_rcu_putref(void *ptr)
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{
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if (--container_of(ptr, struct ipc_rcu_hdr, data)->refcount > 0)
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return;
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if (container_of(ptr, struct ipc_rcu_hdr, data)->is_vmalloc) {
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call_rcu(&container_of(ptr, struct ipc_rcu_grace, data)->rcu,
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ipc_schedule_free);
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} else {
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call_rcu(&container_of(ptr, struct ipc_rcu_grace, data)->rcu,
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ipc_immediate_free);
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}
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}
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|
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/**
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* ipcperms - check IPC permissions
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* @ipcp: IPC permission set
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* @flag: desired permission set.
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*
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* Check user, group, other permissions for access
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* to ipc resources. return 0 if allowed
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*/
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int ipcperms (struct kern_ipc_perm *ipcp, short flag)
|
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{ /* flag will most probably be 0 or S_...UGO from <linux/stat.h> */
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int requested_mode, granted_mode;
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requested_mode = (flag >> 6) | (flag >> 3) | flag;
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granted_mode = ipcp->mode;
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if (current->euid == ipcp->cuid || current->euid == ipcp->uid)
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granted_mode >>= 6;
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else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid))
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granted_mode >>= 3;
|
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/* is there some bit set in requested_mode but not in granted_mode? */
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if ((requested_mode & ~granted_mode & 0007) &&
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!capable(CAP_IPC_OWNER))
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return -1;
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|
|
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return security_ipc_permission(ipcp, flag);
|
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}
|
|
|
|
/*
|
|
* Functions to convert between the kern_ipc_perm structure and the
|
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* old/new ipc_perm structures
|
|
*/
|
|
|
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/**
|
|
* kernel_to_ipc64_perm - convert kernel ipc permissions to user
|
|
* @in: kernel permissions
|
|
* @out: new style IPC permissions
|
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*
|
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* Turn the kernel object 'in' into a set of permissions descriptions
|
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* for returning to userspace (out).
|
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*/
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|
|
|
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void kernel_to_ipc64_perm (struct kern_ipc_perm *in, struct ipc64_perm *out)
|
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{
|
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out->key = in->key;
|
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out->uid = in->uid;
|
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out->gid = in->gid;
|
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out->cuid = in->cuid;
|
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out->cgid = in->cgid;
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out->mode = in->mode;
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out->seq = in->seq;
|
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}
|
|
|
|
/**
|
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* ipc64_perm_to_ipc_perm - convert old ipc permissions to new
|
|
* @in: new style IPC permissions
|
|
* @out: old style IPC permissions
|
|
*
|
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* 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;
|
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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;
|
|
}
|
|
|
|
/*
|
|
* So far only shm_get_stat() calls ipc_get() via shm_get(), so ipc_get()
|
|
* is called with shm_ids.sem locked. Since grow_ary() is also called with
|
|
* shm_ids.sem down(for Shared Memory), there is no need to add read
|
|
* barriers here to gurantee the writes in grow_ary() are seen in order
|
|
* here (for Alpha).
|
|
*
|
|
* However ipc_get() itself does not necessary require ipc_ids.sem down. So
|
|
* if in the future ipc_get() is used by other places without ipc_ids.sem
|
|
* down, then ipc_get() needs read memery barriers as ipc_lock() does.
|
|
*/
|
|
struct kern_ipc_perm* ipc_get(struct ipc_ids* ids, int id)
|
|
{
|
|
struct kern_ipc_perm* out;
|
|
int lid = id % SEQ_MULTIPLIER;
|
|
if(lid >= ids->entries->size)
|
|
return NULL;
|
|
out = ids->entries->p[lid];
|
|
return out;
|
|
}
|
|
|
|
struct kern_ipc_perm* ipc_lock(struct ipc_ids* ids, int id)
|
|
{
|
|
struct kern_ipc_perm* out;
|
|
int lid = id % SEQ_MULTIPLIER;
|
|
struct ipc_id_ary* entries;
|
|
|
|
rcu_read_lock();
|
|
entries = rcu_dereference(ids->entries);
|
|
if(lid >= entries->size) {
|
|
rcu_read_unlock();
|
|
return NULL;
|
|
}
|
|
out = entries->p[lid];
|
|
if(out == NULL) {
|
|
rcu_read_unlock();
|
|
return NULL;
|
|
}
|
|
spin_lock(&out->lock);
|
|
|
|
/* ipc_rmid() may have already freed the ID while ipc_lock
|
|
* was spinning: here verify that the structure is still valid
|
|
*/
|
|
if (out->deleted) {
|
|
spin_unlock(&out->lock);
|
|
rcu_read_unlock();
|
|
return NULL;
|
|
}
|
|
return out;
|
|
}
|
|
|
|
void ipc_lock_by_ptr(struct kern_ipc_perm *perm)
|
|
{
|
|
rcu_read_lock();
|
|
spin_lock(&perm->lock);
|
|
}
|
|
|
|
void ipc_unlock(struct kern_ipc_perm* perm)
|
|
{
|
|
spin_unlock(&perm->lock);
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
int ipc_buildid(struct ipc_ids* ids, int id, int seq)
|
|
{
|
|
return SEQ_MULTIPLIER*seq + id;
|
|
}
|
|
|
|
int ipc_checkid(struct ipc_ids* ids, struct kern_ipc_perm* ipcp, int uid)
|
|
{
|
|
if(uid/SEQ_MULTIPLIER != ipcp->seq)
|
|
return 1;
|
|
return 0;
|
|
}
|
|
|
|
#ifdef __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 /* __ARCH_WANT_IPC_PARSE_VERSION */
|
|
|
|
#ifdef CONFIG_PROC_FS
|
|
static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
|
|
{
|
|
struct ipc_proc_iface *iface = s->private;
|
|
struct kern_ipc_perm *ipc = it;
|
|
loff_t p;
|
|
|
|
/* If we had an ipc id locked before, unlock it */
|
|
if (ipc && ipc != SEQ_START_TOKEN)
|
|
ipc_unlock(ipc);
|
|
|
|
/*
|
|
* p = *pos - 1 (because id 0 starts at position 1)
|
|
* + 1 (because we increment the position by one)
|
|
*/
|
|
for (p = *pos; p <= iface->ids->max_id; p++) {
|
|
if ((ipc = ipc_lock(iface->ids, p)) != NULL) {
|
|
*pos = p + 1;
|
|
return ipc;
|
|
}
|
|
}
|
|
|
|
/* Out of range - return NULL to terminate iteration */
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* File positions: pos 0 -> header, pos n -> ipc id + 1.
|
|
* SeqFile iterator: iterator value locked shp or SEQ_TOKEN_START.
|
|
*/
|
|
static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
|
|
{
|
|
struct ipc_proc_iface *iface = s->private;
|
|
struct kern_ipc_perm *ipc;
|
|
loff_t p;
|
|
|
|
/*
|
|
* Take the lock - this will be released by the corresponding
|
|
* call to stop().
|
|
*/
|
|
down(&iface->ids->sem);
|
|
|
|
/* 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 */
|
|
for (p = *pos - 1; p <= iface->ids->max_id; p++) {
|
|
if ((ipc = ipc_lock(iface->ids, p)) != NULL) {
|
|
*pos = p + 1;
|
|
return ipc;
|
|
}
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
static void sysvipc_proc_stop(struct seq_file *s, void *it)
|
|
{
|
|
struct kern_ipc_perm *ipc = it;
|
|
struct ipc_proc_iface *iface = s->private;
|
|
|
|
/* If we had a locked segment, release it */
|
|
if (ipc && ipc != SEQ_START_TOKEN)
|
|
ipc_unlock(ipc);
|
|
|
|
/* Release the lock we took in start() */
|
|
up(&iface->ids->sem);
|
|
}
|
|
|
|
static int sysvipc_proc_show(struct seq_file *s, void *it)
|
|
{
|
|
struct ipc_proc_iface *iface = s->private;
|
|
|
|
if (it == SEQ_START_TOKEN)
|
|
return seq_puts(s, iface->header);
|
|
|
|
return iface->show(s, it);
|
|
}
|
|
|
|
static 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) {
|
|
int ret;
|
|
struct seq_file *seq;
|
|
|
|
ret = seq_open(file, &sysvipc_proc_seqops);
|
|
if (!ret) {
|
|
seq = file->private_data;
|
|
seq->private = PDE(inode)->data;
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
static struct file_operations sysvipc_proc_fops = {
|
|
.open = sysvipc_proc_open,
|
|
.read = seq_read,
|
|
.llseek = seq_lseek,
|
|
.release = seq_release,
|
|
};
|
|
#endif /* CONFIG_PROC_FS */
|