ipc: add sysctl to specify desired next object id
[linux-3.10.git] / ipc / ipc_sysctl.c
1 /*
2  *  Copyright (C) 2007
3  *
4  *  Author: Eric Biederman <ebiederm@xmision.com>
5  *
6  *  This program is free software; you can redistribute it and/or
7  *  modify it under the terms of the GNU General Public License as
8  *  published by the Free Software Foundation, version 2 of the
9  *  License.
10  */
11
12 #include <linux/module.h>
13 #include <linux/ipc.h>
14 #include <linux/nsproxy.h>
15 #include <linux/sysctl.h>
16 #include <linux/uaccess.h>
17 #include <linux/ipc_namespace.h>
18 #include <linux/msg.h>
19 #include "util.h"
20
21 static void *get_ipc(ctl_table *table)
22 {
23         char *which = table->data;
24         struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
25         which = (which - (char *)&init_ipc_ns) + (char *)ipc_ns;
26         return which;
27 }
28
29 #ifdef CONFIG_PROC_SYSCTL
30 static int proc_ipc_dointvec(ctl_table *table, int write,
31         void __user *buffer, size_t *lenp, loff_t *ppos)
32 {
33         struct ctl_table ipc_table;
34
35         memcpy(&ipc_table, table, sizeof(ipc_table));
36         ipc_table.data = get_ipc(table);
37
38         return proc_dointvec(&ipc_table, write, buffer, lenp, ppos);
39 }
40
41 static int proc_ipc_dointvec_minmax(ctl_table *table, int write,
42         void __user *buffer, size_t *lenp, loff_t *ppos)
43 {
44         struct ctl_table ipc_table;
45
46         memcpy(&ipc_table, table, sizeof(ipc_table));
47         ipc_table.data = get_ipc(table);
48
49         return proc_dointvec_minmax(&ipc_table, write, buffer, lenp, ppos);
50 }
51
52 static int proc_ipc_dointvec_minmax_orphans(ctl_table *table, int write,
53         void __user *buffer, size_t *lenp, loff_t *ppos)
54 {
55         struct ipc_namespace *ns = current->nsproxy->ipc_ns;
56         int err = proc_ipc_dointvec_minmax(table, write, buffer, lenp, ppos);
57
58         if (err < 0)
59                 return err;
60         if (ns->shm_rmid_forced)
61                 shm_destroy_orphaned(ns);
62         return err;
63 }
64
65 static int proc_ipc_callback_dointvec(ctl_table *table, int write,
66         void __user *buffer, size_t *lenp, loff_t *ppos)
67 {
68         struct ctl_table ipc_table;
69         size_t lenp_bef = *lenp;
70         int rc;
71
72         memcpy(&ipc_table, table, sizeof(ipc_table));
73         ipc_table.data = get_ipc(table);
74
75         rc = proc_dointvec(&ipc_table, write, buffer, lenp, ppos);
76
77         if (write && !rc && lenp_bef == *lenp)
78                 /*
79                  * Tunable has successfully been changed by hand. Disable its
80                  * automatic adjustment. This simply requires unregistering
81                  * the notifiers that trigger recalculation.
82                  */
83                 unregister_ipcns_notifier(current->nsproxy->ipc_ns);
84
85         return rc;
86 }
87
88 static int proc_ipc_doulongvec_minmax(ctl_table *table, int write,
89         void __user *buffer, size_t *lenp, loff_t *ppos)
90 {
91         struct ctl_table ipc_table;
92         memcpy(&ipc_table, table, sizeof(ipc_table));
93         ipc_table.data = get_ipc(table);
94
95         return proc_doulongvec_minmax(&ipc_table, write, buffer,
96                                         lenp, ppos);
97 }
98
99 /*
100  * Routine that is called when the file "auto_msgmni" has successfully been
101  * written.
102  * Two values are allowed:
103  * 0: unregister msgmni's callback routine from the ipc namespace notifier
104  *    chain. This means that msgmni won't be recomputed anymore upon memory
105  *    add/remove or ipc namespace creation/removal.
106  * 1: register back the callback routine.
107  */
108 static void ipc_auto_callback(int val)
109 {
110         if (!val)
111                 unregister_ipcns_notifier(current->nsproxy->ipc_ns);
112         else {
113                 /*
114                  * Re-enable automatic recomputing only if not already
115                  * enabled.
116                  */
117                 recompute_msgmni(current->nsproxy->ipc_ns);
118                 cond_register_ipcns_notifier(current->nsproxy->ipc_ns);
119         }
120 }
121
122 static int proc_ipcauto_dointvec_minmax(ctl_table *table, int write,
123         void __user *buffer, size_t *lenp, loff_t *ppos)
124 {
125         struct ctl_table ipc_table;
126         size_t lenp_bef = *lenp;
127         int oldval;
128         int rc;
129
130         memcpy(&ipc_table, table, sizeof(ipc_table));
131         ipc_table.data = get_ipc(table);
132         oldval = *((int *)(ipc_table.data));
133
134         rc = proc_dointvec_minmax(&ipc_table, write, buffer, lenp, ppos);
135
136         if (write && !rc && lenp_bef == *lenp) {
137                 int newval = *((int *)(ipc_table.data));
138                 /*
139                  * The file "auto_msgmni" has correctly been set.
140                  * React by (un)registering the corresponding tunable, if the
141                  * value has changed.
142                  */
143                 if (newval != oldval)
144                         ipc_auto_callback(newval);
145         }
146
147         return rc;
148 }
149
150 #else
151 #define proc_ipc_doulongvec_minmax NULL
152 #define proc_ipc_dointvec          NULL
153 #define proc_ipc_dointvec_minmax   NULL
154 #define proc_ipc_dointvec_minmax_orphans   NULL
155 #define proc_ipc_callback_dointvec NULL
156 #define proc_ipcauto_dointvec_minmax NULL
157 #endif
158
159 static int zero;
160 static int one = 1;
161 #ifdef CONFIG_CHECKPOINT_RESTORE
162 static int int_max = INT_MAX;
163 #endif
164
165 static struct ctl_table ipc_kern_table[] = {
166         {
167                 .procname       = "shmmax",
168                 .data           = &init_ipc_ns.shm_ctlmax,
169                 .maxlen         = sizeof (init_ipc_ns.shm_ctlmax),
170                 .mode           = 0644,
171                 .proc_handler   = proc_ipc_doulongvec_minmax,
172         },
173         {
174                 .procname       = "shmall",
175                 .data           = &init_ipc_ns.shm_ctlall,
176                 .maxlen         = sizeof (init_ipc_ns.shm_ctlall),
177                 .mode           = 0644,
178                 .proc_handler   = proc_ipc_doulongvec_minmax,
179         },
180         {
181                 .procname       = "shmmni",
182                 .data           = &init_ipc_ns.shm_ctlmni,
183                 .maxlen         = sizeof (init_ipc_ns.shm_ctlmni),
184                 .mode           = 0644,
185                 .proc_handler   = proc_ipc_dointvec,
186         },
187         {
188                 .procname       = "shm_rmid_forced",
189                 .data           = &init_ipc_ns.shm_rmid_forced,
190                 .maxlen         = sizeof(init_ipc_ns.shm_rmid_forced),
191                 .mode           = 0644,
192                 .proc_handler   = proc_ipc_dointvec_minmax_orphans,
193                 .extra1         = &zero,
194                 .extra2         = &one,
195         },
196         {
197                 .procname       = "msgmax",
198                 .data           = &init_ipc_ns.msg_ctlmax,
199                 .maxlen         = sizeof (init_ipc_ns.msg_ctlmax),
200                 .mode           = 0644,
201                 .proc_handler   = proc_ipc_dointvec,
202         },
203         {
204                 .procname       = "msgmni",
205                 .data           = &init_ipc_ns.msg_ctlmni,
206                 .maxlen         = sizeof (init_ipc_ns.msg_ctlmni),
207                 .mode           = 0644,
208                 .proc_handler   = proc_ipc_callback_dointvec,
209         },
210         {
211                 .procname       =  "msgmnb",
212                 .data           = &init_ipc_ns.msg_ctlmnb,
213                 .maxlen         = sizeof (init_ipc_ns.msg_ctlmnb),
214                 .mode           = 0644,
215                 .proc_handler   = proc_ipc_dointvec,
216         },
217         {
218                 .procname       = "sem",
219                 .data           = &init_ipc_ns.sem_ctls,
220                 .maxlen         = 4*sizeof (int),
221                 .mode           = 0644,
222                 .proc_handler   = proc_ipc_dointvec,
223         },
224         {
225                 .procname       = "auto_msgmni",
226                 .data           = &init_ipc_ns.auto_msgmni,
227                 .maxlen         = sizeof(int),
228                 .mode           = 0644,
229                 .proc_handler   = proc_ipcauto_dointvec_minmax,
230                 .extra1         = &zero,
231                 .extra2         = &one,
232         },
233 #ifdef CONFIG_CHECKPOINT_RESTORE
234         {
235                 .procname       = "sem_next_id",
236                 .data           = &init_ipc_ns.ids[IPC_SEM_IDS].next_id,
237                 .maxlen         = sizeof(init_ipc_ns.ids[IPC_SEM_IDS].next_id),
238                 .mode           = 0644,
239                 .proc_handler   = proc_ipc_dointvec_minmax,
240                 .extra1         = &zero,
241                 .extra2         = &int_max,
242         },
243         {
244                 .procname       = "msg_next_id",
245                 .data           = &init_ipc_ns.ids[IPC_MSG_IDS].next_id,
246                 .maxlen         = sizeof(init_ipc_ns.ids[IPC_MSG_IDS].next_id),
247                 .mode           = 0644,
248                 .proc_handler   = proc_ipc_dointvec_minmax,
249                 .extra1         = &zero,
250                 .extra2         = &int_max,
251         },
252         {
253                 .procname       = "shm_next_id",
254                 .data           = &init_ipc_ns.ids[IPC_SHM_IDS].next_id,
255                 .maxlen         = sizeof(init_ipc_ns.ids[IPC_SHM_IDS].next_id),
256                 .mode           = 0644,
257                 .proc_handler   = proc_ipc_dointvec_minmax,
258                 .extra1         = &zero,
259                 .extra2         = &int_max,
260         },
261 #endif
262         {}
263 };
264
265 static struct ctl_table ipc_root_table[] = {
266         {
267                 .procname       = "kernel",
268                 .mode           = 0555,
269                 .child          = ipc_kern_table,
270         },
271         {}
272 };
273
274 static int __init ipc_sysctl_init(void)
275 {
276         register_sysctl_table(ipc_root_table);
277         return 0;
278 }
279
280 __initcall(ipc_sysctl_init);