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