| 1 | |
| 2 | |
| 3 | * linux/ipc/util.c
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| 4 | * Copyright (C) 1992 Krishna Balasubramanian
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| 5 | *
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| 6 | * Sep 1997 - Call suser() last after "normal" permission checks so we
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| 7 | * get BSD style process accounting right.
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| 8 | * Occurs in several places in the IPC code.
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| 9 | * Chris Evans, <[email protected]>
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| 10 | * Nov 1999 - ipc helper functions, unified SMP locking
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| 11 | * Manfred Spraul <[email protected]>
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| 12 | * Oct 2002 - One lock per IPC id. RCU ipc_free for lock-free grow_ary().
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| 13 | * Mingming Cao <[email protected]>
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| 14 | * Mar 2006 - support for audit of ipc object properties
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| 15 | * Dustin Kirkland <[email protected]>
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| 16 | * Jun 2006 - namespaces ssupport
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| 17 | * OpenVZ, SWsoft Inc.
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| 18 | * Pavel Emelianov <[email protected]>
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| 19 | *
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| 20 | * General sysv ipc locking scheme:
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| 21 | * rcu_read_lock()
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| 22 | * obtain the ipc object (kern_ipc_perm) by looking up the id in an idr
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| 23 | * tree.
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| 24 | * - perform initial checks (capabilities, auditing and permission,
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| 25 | * etc).
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| 26 | * - perform read-only operations, such as INFO command, that
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| 27 | * do not demand atomicity
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| 28 | * acquire the ipc lock (kern_ipc_perm.lock) through
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| 29 | * ipc_lock_object()
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| 30 | * - perform read-only operations that demand atomicity,
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| 31 | * such as STAT command.
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| 32 | * - perform data updates, such as SET, RMID commands and
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| 33 | * mechanism-specific operations (semop/semtimedop,
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| 34 | * msgsnd/msgrcv, shmat/shmdt).
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| 35 | * drop the ipc lock, through ipc_unlock_object().
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| 36 | * rcu_read_unlock()
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| 37 | *
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| 38 | * The ids->rwsem must be taken when:
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| 39 | * - creating, removing and iterating the existing entries in ipc
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| 40 | * identifier sets.
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| 41 | * - iterating through files under /proc/sysvipc/
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| 42 | *
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| 43 | * Note that sems have a special fast path that avoids kern_ipc_perm.lock -
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| 44 | * see sem_lock().
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| 45 |
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| 46 |
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| 47 | #include <linux/mm.h>
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| 48 | #include <linux/shm.h>
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| 49 | #include <linux/init.h>
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| 50 | #include <linux/msg.h>
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| 51 | #include <linux/vmalloc.h>
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| 52 | #include <linux/slab.h>
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| 53 | #include <linux/notifier.h>
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| 54 | #include <linux/capability.h>
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| 55 | #include <linux/highuid.h>
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| 56 | #include <linux/security.h>
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| 57 | #include <linux/rcupdate.h>
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| 58 | #include <linux/workqueue.h>
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| 59 | #include <linux/seq_file.h>
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| 60 | #include <linux/proc_fs.h>
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| 61 | #include <linux/audit.h>
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| 62 | #include <linux/nsproxy.h>
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| 63 | #include <linux/rwsem.h>
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| 64 | #include <linux/memory.h>
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| 65 | #include <linux/ipc_namespace.h>
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| 66 | #include <linux/rhashtable.h>
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| 67 |
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| 68 | #include <asm/unistd.h>
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| 69 |
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| 70 | #include "util.h"
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| 71 |
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| 72 | struct ipc_proc_iface {
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| 73 | const char *path;
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| 74 | const char *header;
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| 75 | int ids;
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| 76 | int (*show)(struct seq_file *, void *);
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| 77 | };
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| 78 |
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| 79 | |
| 80 | * ipc_init - initialise ipc subsystem
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| 81 | *
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| 82 | * The various sysv ipc resources (semaphores, messages and shared
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| 83 | * memory) are initialised.
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| 84 | *
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| 85 | * A callback routine is registered into the memory hotplug notifier
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| 86 | * chain: since msgmni scales to lowmem this callback routine will be
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| 87 | * called upon successful memory add / remove to recompute msmgni.
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| 88 |
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| 89 | static int __init ipc_init(void)
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| 90 | {
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| 91 | proc_mkdir("sysvipc", NULL);
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| 92 | sem_init();
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| 93 | msg_init();
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| 94 | shm_init();
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| 95 |
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| 96 | return 0;
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| 97 | }
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| 98 | device_initcall(ipc_init);
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| 99 |
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| 100 | static const struct rhashtable_params ipc_kht_params = {
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| 101 | .head_offset = offsetof(struct kern_ipc_perm, khtnode),
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| 102 | .key_offset = offsetof(struct kern_ipc_perm, key),
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| 103 | .key_len = sizeof_field(struct kern_ipc_perm, key),
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| 104 | .automatic_shrinking = true,
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| 105 | };
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| 106 |
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| 107 | |
| 108 | * ipc_init_ids - initialise ipc identifiers
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| 109 | * @ids: ipc identifier set
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| 110 | *
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| 111 | * Set up the sequence range to use for the ipc identifier range (limited
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| 112 | * below ipc_mni) then initialise the keys hashtable and ids idr.
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| 113 |
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| 114 | void ipc_init_ids(struct ipc_ids *ids)
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| 115 | {
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| 116 | ids->in_use = 0;
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| 117 | ids->seq = 0;
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| 118 | init_rwsem(&ids->rwsem);
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| 119 | rhashtable_init(&ids->key_ht, &ipc_kht_params);
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| 120 | idr_init(&ids->ipcs_idr);
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| 121 | ids->max_idx = -1;
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| 122 | ids->last_idx = -1;
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| 123 | #ifdef CONFIG_CHECKPOINT_RESTORE
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| 124 | ids->next_id = -1;
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| 125 | #endif
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| 126 | }
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| 127 |
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| 128 | #ifdef CONFIG_PROC_FS
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| 129 | static const struct proc_ops sysvipc_proc_ops;
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| 130 | |
| 131 | * ipc_init_proc_interface - create a proc interface for sysipc types using a seq_file interface.
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| 132 | * @path: Path in procfs
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| 133 | * @header: Banner to be printed at the beginning of the file.
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| 134 | * @ids: ipc id table to iterate.
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| 135 | * @show: show routine.
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| 136 |
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| 137 | void __init ipc_init_proc_interface(const char *path, const char *header,
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| 138 | int ids, int (*show)(struct seq_file *, void *))
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| 139 | {
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| 140 | struct proc_dir_entry *pde;
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| 141 | struct ipc_proc_iface *iface;
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| 142 |
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| 143 | iface = kmalloc(sizeof(*iface), GFP_KERNEL);
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| 144 | if (!iface)
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| 145 | return;
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| 146 | iface->path = path;
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| 147 | iface->header = header;
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| 148 | iface->ids = ids;
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| 149 | iface->show = show;
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| 150 |
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| 151 | pde = proc_create_data(path,
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| 152 | S_IRUGO,
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| 153 | NULL,
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| 154 | &sysvipc_proc_ops,
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| 155 | iface);
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| 156 | if (!pde)
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| 157 | kfree(iface);
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| 158 | }
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| 159 | #endif
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| 160 |
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| 161 | |
| 162 | * ipc_findkey - find a key in an ipc identifier set
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| 163 | * @ids: ipc identifier set
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| 164 | * @key: key to find
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| 165 | *
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| 166 | * Returns the locked pointer to the ipc structure if found or NULL
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| 167 | * otherwise. If key is found ipc points to the owning ipc structure
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| 168 | *
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| 169 | * Called with writer ipc_ids.rwsem held.
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| 170 |
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| 171 | static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key)
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| 172 | {
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| 173 | struct kern_ipc_perm *ipcp;
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| 174 |
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| 175 | ipcp = rhashtable_lookup_fast(&ids->key_ht, &key,
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| 176 | ipc_kht_params);
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| 177 | if (!ipcp)
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| 178 | return NULL;
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| 179 |
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| 180 | rcu_read_lock();
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| 181 | ipc_lock_object(ipcp);
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| 182 | return ipcp;
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| 183 | }
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| 184 |
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| 185 | |
| 186 | * Insert new IPC object into idr tree, and set sequence number and id
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| 187 | * in the correct order.
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| 188 | * Especially:
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| 189 | * - the sequence number must be set before inserting the object into the idr,
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| 190 | * because the sequence number is accessed without a lock.
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| 191 | * - the id can/must be set after inserting the object into the idr.
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| 192 | * All accesses must be done after getting kern_ipc_perm.lock.
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| 193 | *
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| 194 | * The caller must own kern_ipc_perm.lock.of the new object.
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| 195 | * On error, the function returns a (negative) error code.
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| 196 | *
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| 197 | * To conserve sequence number space, especially with extended ipc_mni,
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| 198 | * the sequence number is incremented only when the returned ID is less than
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| 199 | * the last one.
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| 200 |
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| 201 | static inline int ipc_idr_alloc(struct ipc_ids *ids, struct kern_ipc_perm *new)
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| 202 | {
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| 203 | int idx, next_id = -1;
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| 204 |
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| 205 | #ifdef CONFIG_CHECKPOINT_RESTORE
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| 206 | next_id = ids->next_id;
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| 207 | ids->next_id = -1;
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| 208 | #endif
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| 209 |
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| 210 | |
| 211 | * As soon as a new object is inserted into the idr,
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| 212 | * ipc_obtain_object_idr() or ipc_obtain_object_check() can find it,
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| 213 | * and the lockless preparations for ipc operations can start.
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| 214 | * This means especially: permission checks, audit calls, allocation
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| 215 | * of undo structures, ...
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| 216 | *
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| 217 | * Thus the object must be fully initialized, and if something fails,
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| 218 | * then the full tear-down sequence must be followed.
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| 219 | * (i.e.: set new->deleted, reduce refcount, call_rcu())
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| 220 |
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| 221 |
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| 222 | if (next_id < 0) {
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| 223 | int max_idx;
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| 224 |
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| 225 | max_idx = max(ids->in_use*3/2, ipc_min_cycle);
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| 226 | max_idx = min(max_idx, ipc_mni);
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| 227 |
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| 228 |
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| 229 | idx = idr_alloc_cyclic(&ids->ipcs_idr, NULL, 0, max_idx,
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| 230 | GFP_NOWAIT);
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| 231 |
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| 232 | if (idx >= 0) {
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| 233 | |
| 234 | * idx got allocated successfully.
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| 235 | * Now calculate the sequence number and set the
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| 236 | * pointer for real.
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| 237 |
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| 238 | if (idx <= ids->last_idx) {
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| 239 | ids->seq++;
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| 240 | if (ids->seq >= ipcid_seq_max())
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| 241 | ids->seq = 0;
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| 242 | }
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| 243 | ids->last_idx = idx;
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| 244 |
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| 245 | new->seq = ids->seq;
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| 246 | |
| 247 | * inside idr_replace, as part of
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| 248 | * rcu_assign_pointer
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| 249 |
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| 250 | idr_replace(&ids->ipcs_idr, new, idx);
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| 251 | }
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| 252 | } else {
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| 253 | new->seq = ipcid_to_seqx(next_id);
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| 254 | idx = idr_alloc(&ids->ipcs_idr, new, ipcid_to_idx(next_id),
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| 255 | 0, GFP_NOWAIT);
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| 256 | }
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| 257 | if (idx >= 0)
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| 258 | new->id = (new->seq << ipcmni_seq_shift()) + idx;
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| 259 | return idx;
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| 260 | }
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| 261 |
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| 262 | |
| 263 | * ipc_addid - add an ipc identifier
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| 264 | * @ids: ipc identifier set
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| 265 | * @new: new ipc permission set
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| 266 | * @limit: limit for the number of used ids
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| 267 | *
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| 268 | * Add an entry 'new' to the ipc ids idr. The permissions object is
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| 269 | * initialised and the first free entry is set up and the index assigned
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| 270 | * is returned. The 'new' entry is returned in a locked state on success.
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| 271 | *
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| 272 | * On failure the entry is not locked and a negative err-code is returned.
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| 273 | * The caller must use ipc_rcu_putref() to free the identifier.
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| 274 | *
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| 275 | * Called with writer ipc_ids.rwsem held.
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| 276 |
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| 277 | int ipc_addid(struct ipc_ids *ids, struct kern_ipc_perm *new, int limit)
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| 278 | {
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| 279 | kuid_t euid;
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| 280 | kgid_t egid;
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| 281 | int idx, err;
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| 282 |
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| 283 |
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| 284 | refcount_set(&new->refcount, 1);
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| 285 |
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| 286 | if (limit > ipc_mni)
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| 287 | limit = ipc_mni;
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| 288 |
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| 289 | if (ids->in_use >= limit)
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| 290 | return -ENOSPC;
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| 291 |
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| 292 | idr_preload(GFP_KERNEL);
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| 293 |
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| 294 | spin_lock_init(&new->lock);
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| 295 | rcu_read_lock();
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| 296 | spin_lock(&new->lock);
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| 297 |
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| 298 | current_euid_egid(&euid, &egid);
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| 299 | new->cuid = new->uid = euid;
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| 300 | new->gid = new->cgid = egid;
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| 301 |
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| 302 | new->deleted = false;
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| 303 |
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| 304 | idx = ipc_idr_alloc(ids, new);
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| 305 | idr_preload_end();
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| 306 |
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| 307 | if (idx >= 0 && new->key != IPC_PRIVATE) {
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| 308 | err = rhashtable_insert_fast(&ids->key_ht, &new->khtnode,
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| 309 | ipc_kht_params);
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| 310 | if (err < 0) {
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| 311 | idr_remove(&ids->ipcs_idr, idx);
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| 312 | idx = err;
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| 313 | }
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| 314 | }
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| 315 | if (idx < 0) {
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| 316 | new->deleted = true;
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| 317 | spin_unlock(&new->lock);
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| 318 | rcu_read_unlock();
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| 319 | return idx;
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| 320 | }
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| 321 |
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| 322 | ids->in_use++;
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| 323 | if (idx > ids->max_idx)
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| 324 | ids->max_idx = idx;
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| 325 | return idx;
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| 326 | }
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| 327 |
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| 328 | |
| 329 | * ipcget_new - create a new ipc object
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| 330 | * @ns: ipc namespace
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| 331 | * @ids: ipc identifier set
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| 332 | * @ops: the actual creation routine to call
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| 333 | * @params: its parameters
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| 334 | *
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| 335 | * This routine is called by sys_msgget, sys_semget() and sys_shmget()
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| 336 | * when the key is IPC_PRIVATE.
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| 337 |
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| 338 | static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
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| 339 | const struct ipc_ops *ops, struct ipc_params *params)
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| 340 | {
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| 341 | int err;
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| 342 |
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| 343 | down_write(&ids->rwsem);
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| 344 | err = ops->getnew(ns, params);
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| 345 | up_write(&ids->rwsem);
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| 346 | return err;
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| 347 | }
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| 348 |
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| 349 | |
| 350 | * ipc_check_perms - check security and permissions for an ipc object
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| 351 | * @ns: ipc namespace
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| 352 | * @ipcp: ipc permission set
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| 353 | * @ops: the actual security routine to call
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| 354 | * @params: its parameters
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| 355 | *
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| 356 | * This routine is called by sys_msgget(), sys_semget() and sys_shmget()
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| 357 | * when the key is not IPC_PRIVATE and that key already exists in the
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| 358 | * ds IDR.
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| 359 | *
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| 360 | * On success, the ipc id is returned.
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| 361 | *
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| 362 | * It is called with ipc_ids.rwsem and ipcp->lock held.
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| 363 |
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| 364 | static int ipc_check_perms(struct ipc_namespace *ns,
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| 365 | struct kern_ipc_perm *ipcp,
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| 366 | const struct ipc_ops *ops,
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| 367 | struct ipc_params *params)
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| 368 | {
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| 369 | int err;
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| 370 |
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| 371 | if (ipcperms(ns, ipcp, params->flg))
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| 372 | err = -EACCES;
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| 373 | else {
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| 374 | err = ops->associate(ipcp, params->flg);
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| 375 | if (!err)
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| 376 | err = ipcp->id;
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| 377 | }
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| 378 |
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| 379 | return err;
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| 380 | }
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| 381 |
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| 382 | |
| 383 | * ipcget_public - get an ipc object or create a new one
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| 384 | * @ns: ipc namespace
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| 385 | * @ids: ipc identifier set
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| 386 | * @ops: the actual creation routine to call
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| 387 | * @params: its parameters
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| 388 | *
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| 389 | * This routine is called by sys_msgget, sys_semget() and sys_shmget()
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| 390 | * when the key is not IPC_PRIVATE.
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| 391 | * It adds a new entry if the key is not found and does some permission
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| 392 | * / security checkings if the key is found.
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| 393 | *
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| 394 | * On success, the ipc id is returned.
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| 395 |
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| 396 | static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
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| 397 | const struct ipc_ops *ops, struct ipc_params *params)
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| 398 | {
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| 399 | struct kern_ipc_perm *ipcp;
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| 400 | int flg = params->flg;
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| 401 | int err;
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| 402 |
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| 403 | |
| 404 | * Take the lock as a writer since we are potentially going to add
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| 405 | * a new entry + read locks are not "upgradable"
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| 406 |
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| 407 | down_write(&ids->rwsem);
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| 408 | ipcp = ipc_findkey(ids, params->key);
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| 409 | if (ipcp == NULL) {
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| 410 |
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| 411 | if (!(flg & IPC_CREAT))
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| 412 | err = -ENOENT;
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| 413 | else
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| 414 | err = ops->getnew(ns, params);
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| 415 | } else {
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| 416 |
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| 417 |
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| 418 | if (flg & IPC_CREAT && flg & IPC_EXCL)
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| 419 | err = -EEXIST;
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| 420 | else {
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| 421 | err = 0;
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| 422 | if (ops->more_checks)
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| 423 | err = ops->more_checks(ipcp, params);
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| 424 | if (!err)
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| 425 | |
| 426 | * ipc_check_perms returns the IPC id on
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| 427 | * success
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| 428 |
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| 429 | err = ipc_check_perms(ns, ipcp, ops, params);
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| 430 | }
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| 431 | ipc_unlock(ipcp);
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| 432 | }
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| 433 | up_write(&ids->rwsem);
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| 434 |
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| 435 | return err;
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| 436 | }
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| 437 |
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| 438 | |
| 439 | * ipc_kht_remove - remove an ipc from the key hashtable
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| 440 | * @ids: ipc identifier set
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| 441 | * @ipcp: ipc perm structure containing the key to remove
|
| 442 | *
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| 443 | * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
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| 444 | * before this function is called, and remain locked on the exit.
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| 445 |
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| 446 | static void ipc_kht_remove(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
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| 447 | {
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| 448 | if (ipcp->key != IPC_PRIVATE)
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| 449 | rhashtable_remove_fast(&ids->key_ht, &ipcp->khtnode,
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| 450 | ipc_kht_params);
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| 451 | }
|
| 452 |
|
| 453 | |
| 454 | * ipc_rmid - remove an ipc identifier
|
| 455 | * @ids: ipc identifier set
|
| 456 | * @ipcp: ipc perm structure containing the identifier to remove
|
| 457 | *
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| 458 | * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
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| 459 | * before this function is called, and remain locked on the exit.
|
| 460 |
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| 461 | void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
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| 462 | {
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| 463 | int idx = ipcid_to_idx(ipcp->id);
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| 464 |
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| 465 | idr_remove(&ids->ipcs_idr, idx);
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| 466 | ipc_kht_remove(ids, ipcp);
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| 467 | ids->in_use--;
|
| 468 | ipcp->deleted = true;
|
| 469 |
|
| 470 | if (unlikely(idx == ids->max_idx)) {
|
| 471 | do {
|
| 472 | idx--;
|
| 473 | if (idx == -1)
|
| 474 | break;
|
| 475 | } while (!idr_find(&ids->ipcs_idr, idx));
|
| 476 | ids->max_idx = idx;
|
| 477 | }
|
| 478 | }
|
| 479 |
|
| 480 | |
| 481 | * ipc_set_key_private - switch the key of an existing ipc to IPC_PRIVATE
|
| 482 | * @ids: ipc identifier set
|
| 483 | * @ipcp: ipc perm structure containing the key to modify
|
| 484 | *
|
| 485 | * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
|
| 486 | * before this function is called, and remain locked on the exit.
|
| 487 |
|
| 488 | void ipc_set_key_private(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
|
| 489 | {
|
| 490 | ipc_kht_remove(ids, ipcp);
|
| 491 | ipcp->key = IPC_PRIVATE;
|
| 492 | }
|
| 493 |
|
| 494 | bool ipc_rcu_getref(struct kern_ipc_perm *ptr)
|
| 495 | {
|
| 496 | return refcount_inc_not_zero(&ptr->refcount);
|
| 497 | }
|
| 498 |
|
| 499 | void ipc_rcu_putref(struct kern_ipc_perm *ptr,
|
| 500 | void (*func)(struct rcu_head *head))
|
| 501 | {
|
| 502 | if (!refcount_dec_and_test(&ptr->refcount))
|
| 503 | return;
|
| 504 |
|
| 505 | call_rcu(&ptr->rcu, func);
|
| 506 | }
|
| 507 |
|
| 508 | |
| 509 | * ipcperms - check ipc permissions
|
| 510 | * @ns: ipc namespace
|
| 511 | * @ipcp: ipc permission set
|
| 512 | * @flag: desired permission set
|
| 513 | *
|
| 514 | * Check user, group, other permissions for access
|
| 515 | * to ipc resources. return 0 if allowed
|
| 516 | *
|
| 517 | * @flag will most probably be 0 or ``S_...UGO`` from <linux/stat.h>
|
| 518 |
|
| 519 | int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flag)
|
| 520 | {
|
| 521 | kuid_t euid = current_euid();
|
| 522 | int requested_mode, granted_mode;
|
| 523 |
|
| 524 | audit_ipc_obj(ipcp);
|
| 525 | requested_mode = (flag >> 6) | (flag >> 3) | flag;
|
| 526 | granted_mode = ipcp->mode;
|
| 527 | if (uid_eq(euid, ipcp->cuid) ||
|
| 528 | uid_eq(euid, ipcp->uid))
|
| 529 | granted_mode >>= 6;
|
| 530 | else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid))
|
| 531 | granted_mode >>= 3;
|
| 532 |
|
| 533 | if ((requested_mode & ~granted_mode & 0007) &&
|
| 534 | !ns_capable(ns->user_ns, CAP_IPC_OWNER))
|
| 535 | return -1;
|
| 536 |
|
| 537 | return security_ipc_permission(ipcp, flag);
|
| 538 | }
|
| 539 |
|
| 540 | |
| 541 | * Functions to convert between the kern_ipc_perm structure and the
|
| 542 | * old/new ipc_perm structures
|
| 543 |
|
| 544 |
|
| 545 | |
| 546 | * kernel_to_ipc64_perm - convert kernel ipc permissions to user
|
| 547 | * @in: kernel permissions
|
| 548 | * @out: new style ipc permissions
|
| 549 | *
|
| 550 | * Turn the kernel object @in into a set of permissions descriptions
|
| 551 | * for returning to userspace (@out).
|
| 552 |
|
| 553 | void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out)
|
| 554 | {
|
| 555 | out->key = in->key;
|
| 556 | out->uid = from_kuid_munged(current_user_ns(), in->uid);
|
| 557 | out->gid = from_kgid_munged(current_user_ns(), in->gid);
|
| 558 | out->cuid = from_kuid_munged(current_user_ns(), in->cuid);
|
| 559 | out->cgid = from_kgid_munged(current_user_ns(), in->cgid);
|
| 560 | out->mode = in->mode;
|
| 561 | out->seq = in->seq;
|
| 562 | }
|
| 563 |
|
| 564 | |
| 565 | * ipc64_perm_to_ipc_perm - convert new ipc permissions to old
|
| 566 | * @in: new style ipc permissions
|
| 567 | * @out: old style ipc permissions
|
| 568 | *
|
| 569 | * Turn the new style permissions object @in into a compatibility
|
| 570 | * object and store it into the @out pointer.
|
| 571 |
|
| 572 | void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out)
|
| 573 | {
|
| 574 | out->key = in->key;
|
| 575 | SET_UID(out->uid, in->uid);
|
| 576 | SET_GID(out->gid, in->gid);
|
| 577 | SET_UID(out->cuid, in->cuid);
|
| 578 | SET_GID(out->cgid, in->cgid);
|
| 579 | out->mode = in->mode;
|
| 580 | out->seq = in->seq;
|
| 581 | }
|
| 582 |
|
| 583 | |
| 584 | * ipc_obtain_object_idr
|
| 585 | * @ids: ipc identifier set
|
| 586 | * @id: ipc id to look for
|
| 587 | *
|
| 588 | * Look for an id in the ipc ids idr and return associated ipc object.
|
| 589 | *
|
| 590 | * Call inside the RCU critical section.
|
| 591 | * The ipc object is *not* locked on exit.
|
| 592 |
|
| 593 | struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id)
|
| 594 | {
|
| 595 | struct kern_ipc_perm *out;
|
| 596 | int idx = ipcid_to_idx(id);
|
| 597 |
|
| 598 | out = idr_find(&ids->ipcs_idr, idx);
|
| 599 | if (!out)
|
| 600 | return ERR_PTR(-EINVAL);
|
| 601 |
|
| 602 | return out;
|
| 603 | }
|
| 604 |
|
| 605 | |
| 606 | * ipc_obtain_object_check
|
| 607 | * @ids: ipc identifier set
|
| 608 | * @id: ipc id to look for
|
| 609 | *
|
| 610 | * Similar to ipc_obtain_object_idr() but also checks the ipc object
|
| 611 | * sequence number.
|
| 612 | *
|
| 613 | * Call inside the RCU critical section.
|
| 614 | * The ipc object is *not* locked on exit.
|
| 615 |
|
| 616 | struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id)
|
| 617 | {
|
| 618 | struct kern_ipc_perm *out = ipc_obtain_object_idr(ids, id);
|
| 619 |
|
| 620 | if (IS_ERR(out))
|
| 621 | goto out;
|
| 622 |
|
| 623 | if (ipc_checkid(out, id))
|
| 624 | return ERR_PTR(-EINVAL);
|
| 625 | out:
|
| 626 | return out;
|
| 627 | }
|
| 628 |
|
| 629 | |
| 630 | * ipcget - Common sys_*get() code
|
| 631 | * @ns: namespace
|
| 632 | * @ids: ipc identifier set
|
| 633 | * @ops: operations to be called on ipc object creation, permission checks
|
| 634 | * and further checks
|
| 635 | * @params: the parameters needed by the previous operations.
|
| 636 | *
|
| 637 | * Common routine called by sys_msgget(), sys_semget() and sys_shmget().
|
| 638 |
|
| 639 | int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
|
| 640 | const struct ipc_ops *ops, struct ipc_params *params)
|
| 641 | {
|
| 642 | if (params->key == IPC_PRIVATE)
|
| 643 | return ipcget_new(ns, ids, ops, params);
|
| 644 | else
|
| 645 | return ipcget_public(ns, ids, ops, params);
|
| 646 | }
|
| 647 |
|
| 648 | |
| 649 | * ipc_update_perm - update the permissions of an ipc object
|
| 650 | * @in: the permission given as input.
|
| 651 | * @out: the permission of the ipc to set.
|
| 652 |
|
| 653 | int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out)
|
| 654 | {
|
| 655 | kuid_t uid = make_kuid(current_user_ns(), in->uid);
|
| 656 | kgid_t gid = make_kgid(current_user_ns(), in->gid);
|
| 657 | if (!uid_valid(uid) || !gid_valid(gid))
|
| 658 | return -EINVAL;
|
| 659 |
|
| 660 | out->uid = uid;
|
| 661 | out->gid = gid;
|
| 662 | out->mode = (out->mode & ~S_IRWXUGO)
|
| 663 | | (in->mode & S_IRWXUGO);
|
| 664 |
|
| 665 | return 0;
|
| 666 | }
|
| 667 |
|
| 668 | |
| 669 | * ipcctl_obtain_check - retrieve an ipc object and check permissions
|
| 670 | * @ns: ipc namespace
|
| 671 | * @ids: the table of ids where to look for the ipc
|
| 672 | * @id: the id of the ipc to retrieve
|
| 673 | * @cmd: the cmd to check
|
| 674 | * @perm: the permission to set
|
| 675 | * @extra_perm: one extra permission parameter used by msq
|
| 676 | *
|
| 677 | * This function does some common audit and permissions check for some IPC_XXX
|
| 678 | * cmd and is called from semctl_down, shmctl_down and msgctl_down.
|
| 679 | *
|
| 680 | * It:
|
| 681 | * - retrieves the ipc object with the given id in the given table.
|
| 682 | * - performs some audit and permission check, depending on the given cmd
|
| 683 | * - returns a pointer to the ipc object or otherwise, the corresponding
|
| 684 | * error.
|
| 685 | *
|
| 686 | * Call holding the both the rwsem and the rcu read lock.
|
| 687 |
|
| 688 | struct kern_ipc_perm *ipcctl_obtain_check(struct ipc_namespace *ns,
|
| 689 | struct ipc_ids *ids, int id, int cmd,
|
| 690 | struct ipc64_perm *perm, int extra_perm)
|
| 691 | {
|
| 692 | kuid_t euid;
|
| 693 | int err = -EPERM;
|
| 694 | struct kern_ipc_perm *ipcp;
|
| 695 |
|
| 696 | ipcp = ipc_obtain_object_check(ids, id);
|
| 697 | if (IS_ERR(ipcp)) {
|
| 698 | err = PTR_ERR(ipcp);
|
| 699 | goto err;
|
| 700 | }
|
| 701 |
|
| 702 | audit_ipc_obj(ipcp);
|
| 703 | if (cmd == IPC_SET)
|
| 704 | audit_ipc_set_perm(extra_perm, perm->uid,
|
| 705 | perm->gid, perm->mode);
|
| 706 |
|
| 707 | euid = current_euid();
|
| 708 | if (uid_eq(euid, ipcp->cuid) || uid_eq(euid, ipcp->uid) ||
|
| 709 | ns_capable(ns->user_ns, CAP_SYS_ADMIN))
|
| 710 | return ipcp;
|
| 711 | err:
|
| 712 | return ERR_PTR(err);
|
| 713 | }
|
| 714 |
|
| 715 | #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
|
| 716 |
|
| 717 |
|
| 718 | |
| 719 | * ipc_parse_version - ipc call version
|
| 720 | * @cmd: pointer to command
|
| 721 | *
|
| 722 | * Return IPC_64 for new style IPC and IPC_OLD for old style IPC.
|
| 723 | * The @cmd value is turned from an encoding command and version into
|
| 724 | * just the command code.
|
| 725 |
|
| 726 | int ipc_parse_version(int *cmd)
|
| 727 | {
|
| 728 | if (*cmd & IPC_64) {
|
| 729 | *cmd ^= IPC_64;
|
| 730 | return IPC_64;
|
| 731 | } else {
|
| 732 | return IPC_OLD;
|
| 733 | }
|
| 734 | }
|
| 735 |
|
| 736 | #endif
|
| 737 |
|
| 738 | #ifdef CONFIG_PROC_FS
|
| 739 | struct ipc_proc_iter {
|
| 740 | struct ipc_namespace *ns;
|
| 741 | struct pid_namespace *pid_ns;
|
| 742 | struct ipc_proc_iface *iface;
|
| 743 | };
|
| 744 |
|
| 745 | struct pid_namespace *ipc_seq_pid_ns(struct seq_file *s)
|
| 746 | {
|
| 747 | struct ipc_proc_iter *iter = s->private;
|
| 748 | return iter->pid_ns;
|
| 749 | }
|
| 750 |
|
| 751 | |
| 752 | * This routine locks the ipc structure found at least at position pos.
|
| 753 |
|
| 754 | static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos,
|
| 755 | loff_t *new_pos)
|
| 756 | {
|
| 757 | struct kern_ipc_perm *ipc;
|
| 758 | int total, id;
|
| 759 |
|
| 760 | total = 0;
|
| 761 | for (id = 0; id < pos && total < ids->in_use; id++) {
|
| 762 | ipc = idr_find(&ids->ipcs_idr, id);
|
| 763 | if (ipc != NULL)
|
| 764 | total++;
|
| 765 | }
|
| 766 |
|
| 767 | ipc = NULL;
|
| 768 | if (total >= ids->in_use)
|
| 769 | goto out;
|
| 770 |
|
| 771 | for (; pos < ipc_mni; pos++) {
|
| 772 | ipc = idr_find(&ids->ipcs_idr, pos);
|
| 773 | if (ipc != NULL) {
|
| 774 | rcu_read_lock();
|
| 775 | ipc_lock_object(ipc);
|
| 776 | break;
|
| 777 | }
|
| 778 | }
|
| 779 | out:
|
| 780 | *new_pos = pos + 1;
|
| 781 | return ipc;
|
| 782 | }
|
| 783 |
|
| 784 | static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
|
| 785 | {
|
| 786 | struct ipc_proc_iter *iter = s->private;
|
| 787 | struct ipc_proc_iface *iface = iter->iface;
|
| 788 | struct kern_ipc_perm *ipc = it;
|
| 789 |
|
| 790 |
|
| 791 | if (ipc && ipc != SEQ_START_TOKEN)
|
| 792 | ipc_unlock(ipc);
|
| 793 |
|
| 794 | return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos);
|
| 795 | }
|
| 796 |
|
| 797 | |
| 798 | * File positions: pos 0 -> header, pos n -> ipc id = n - 1.
|
| 799 | * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START.
|
| 800 |
|
| 801 | static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
|
| 802 | {
|
| 803 | struct ipc_proc_iter *iter = s->private;
|
| 804 | struct ipc_proc_iface *iface = iter->iface;
|
| 805 | struct ipc_ids *ids;
|
| 806 |
|
| 807 | ids = &iter->ns->ids[iface->ids];
|
| 808 |
|
| 809 | |
| 810 | * Take the lock - this will be released by the corresponding
|
| 811 | * call to stop().
|
| 812 |
|
| 813 | down_read(&ids->rwsem);
|
| 814 |
|
| 815 |
|
| 816 | if (*pos < 0)
|
| 817 | return NULL;
|
| 818 |
|
| 819 |
|
| 820 | if (*pos == 0)
|
| 821 | return SEQ_START_TOKEN;
|
| 822 |
|
| 823 |
|
| 824 | return sysvipc_find_ipc(ids, *pos - 1, pos);
|
| 825 | }
|
| 826 |
|
| 827 | static void sysvipc_proc_stop(struct seq_file *s, void *it)
|
| 828 | {
|
| 829 | struct kern_ipc_perm *ipc = it;
|
| 830 | struct ipc_proc_iter *iter = s->private;
|
| 831 | struct ipc_proc_iface *iface = iter->iface;
|
| 832 | struct ipc_ids *ids;
|
| 833 |
|
| 834 |
|
| 835 | if (ipc && ipc != SEQ_START_TOKEN)
|
| 836 | ipc_unlock(ipc);
|
| 837 |
|
| 838 | ids = &iter->ns->ids[iface->ids];
|
| 839 |
|
| 840 | up_read(&ids->rwsem);
|
| 841 | }
|
| 842 |
|
| 843 | static int sysvipc_proc_show(struct seq_file *s, void *it)
|
| 844 | {
|
| 845 | struct ipc_proc_iter *iter = s->private;
|
| 846 | struct ipc_proc_iface *iface = iter->iface;
|
| 847 |
|
| 848 | if (it == SEQ_START_TOKEN) {
|
| 849 | seq_puts(s, iface->header);
|
| 850 | return 0;
|
| 851 | }
|
| 852 |
|
| 853 | return iface->show(s, it);
|
| 854 | }
|
| 855 |
|
| 856 | static const struct seq_operations sysvipc_proc_seqops = {
|
| 857 | .start = sysvipc_proc_start,
|
| 858 | .stop = sysvipc_proc_stop,
|
| 859 | .next = sysvipc_proc_next,
|
| 860 | .show = sysvipc_proc_show,
|
| 861 | };
|
| 862 |
|
| 863 | static int sysvipc_proc_open(struct inode *inode, struct file *file)
|
| 864 | {
|
| 865 | struct ipc_proc_iter *iter;
|
| 866 |
|
| 867 | iter = __seq_open_private(file, &sysvipc_proc_seqops, sizeof(*iter));
|
| 868 | if (!iter)
|
| 869 | return -ENOMEM;
|
| 870 |
|
| 871 | iter->iface = PDE_DATA(inode);
|
| 872 | iter->ns = get_ipc_ns(current->nsproxy->ipc_ns);
|
| 873 | iter->pid_ns = get_pid_ns(task_active_pid_ns(current));
|
| 874 |
|
| 875 | return 0;
|
| 876 | }
|
| 877 |
|
| 878 | static int sysvipc_proc_release(struct inode *inode, struct file *file)
|
| 879 | {
|
| 880 | struct seq_file *seq = file->private_data;
|
| 881 | struct ipc_proc_iter *iter = seq->private;
|
| 882 | put_ipc_ns(iter->ns);
|
| 883 | put_pid_ns(iter->pid_ns);
|
| 884 | return seq_release_private(inode, file);
|
| 885 | }
|
| 886 |
|
| 887 | static const struct proc_ops sysvipc_proc_ops = {
|
| 888 | .proc_flags = PROC_ENTRY_PERMANENT,
|
| 889 | .proc_open = sysvipc_proc_open,
|
| 890 | .proc_read = seq_read,
|
| 891 | .proc_lseek = seq_lseek,
|
| 892 | .proc_release = sysvipc_proc_release,
|
| 893 | };
|
| 894 | #endif
|