ipc/sem.c: rewrite undo list locking
[linux-2.6.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 /*
30  * Routine that is called when a tunable has successfully been changed by
31  * hand and it has a callback routine registered on the ipc namespace notifier
32  * chain: we don't want such tunables to be recomputed anymore upon memory
33  * add/remove or ipc namespace creation/removal.
34  * They can come back to a recomputable state by being set to a <0 value.
35  */
36 static void tunable_set_callback(int val)
37 {
38         if (val >= 0)
39                 unregister_ipcns_notifier(current->nsproxy->ipc_ns);
40         else {
41                 /*
42                  * Re-enable automatic recomputing only if not already
43                  * enabled.
44                  */
45                 recompute_msgmni(current->nsproxy->ipc_ns);
46                 cond_register_ipcns_notifier(current->nsproxy->ipc_ns);
47         }
48 }
49
50 #ifdef CONFIG_PROC_FS
51 static int proc_ipc_dointvec(ctl_table *table, int write, struct file *filp,
52         void __user *buffer, size_t *lenp, loff_t *ppos)
53 {
54         struct ctl_table ipc_table;
55         memcpy(&ipc_table, table, sizeof(ipc_table));
56         ipc_table.data = get_ipc(table);
57
58         return proc_dointvec(&ipc_table, write, filp, buffer, lenp, ppos);
59 }
60
61 static int proc_ipc_callback_dointvec(ctl_table *table, int write,
62         struct file *filp, void __user *buffer, size_t *lenp, loff_t *ppos)
63 {
64         struct ctl_table ipc_table;
65         size_t lenp_bef = *lenp;
66         int rc;
67
68         memcpy(&ipc_table, table, sizeof(ipc_table));
69         ipc_table.data = get_ipc(table);
70
71         rc = proc_dointvec(&ipc_table, write, filp, buffer, lenp, ppos);
72
73         if (write && !rc && lenp_bef == *lenp)
74                 tunable_set_callback(*((int *)(ipc_table.data)));
75
76         return rc;
77 }
78
79 static int proc_ipc_doulongvec_minmax(ctl_table *table, int write,
80         struct file *filp, void __user *buffer, size_t *lenp, loff_t *ppos)
81 {
82         struct ctl_table ipc_table;
83         memcpy(&ipc_table, table, sizeof(ipc_table));
84         ipc_table.data = get_ipc(table);
85
86         return proc_doulongvec_minmax(&ipc_table, write, filp, buffer,
87                                         lenp, ppos);
88 }
89
90 #else
91 #define proc_ipc_doulongvec_minmax NULL
92 #define proc_ipc_dointvec          NULL
93 #define proc_ipc_callback_dointvec NULL
94 #endif
95
96 #ifdef CONFIG_SYSCTL_SYSCALL
97 /* The generic sysctl ipc data routine. */
98 static int sysctl_ipc_data(ctl_table *table, int __user *name, int nlen,
99                 void __user *oldval, size_t __user *oldlenp,
100                 void __user *newval, size_t newlen)
101 {
102         size_t len;
103         void *data;
104
105         /* Get out of I don't have a variable */
106         if (!table->data || !table->maxlen)
107                 return -ENOTDIR;
108
109         data = get_ipc(table);
110         if (!data)
111                 return -ENOTDIR;
112
113         if (oldval && oldlenp) {
114                 if (get_user(len, oldlenp))
115                         return -EFAULT;
116                 if (len) {
117                         if (len > table->maxlen)
118                                 len = table->maxlen;
119                         if (copy_to_user(oldval, data, len))
120                                 return -EFAULT;
121                         if (put_user(len, oldlenp))
122                                 return -EFAULT;
123                 }
124         }
125
126         if (newval && newlen) {
127                 if (newlen > table->maxlen)
128                         newlen = table->maxlen;
129
130                 if (copy_from_user(data, newval, newlen))
131                         return -EFAULT;
132         }
133         return 1;
134 }
135
136 static int sysctl_ipc_registered_data(ctl_table *table, int __user *name,
137                 int nlen, void __user *oldval, size_t __user *oldlenp,
138                 void __user *newval, size_t newlen)
139 {
140         int rc;
141
142         rc = sysctl_ipc_data(table, name, nlen, oldval, oldlenp, newval,
143                 newlen);
144
145         if (newval && newlen && rc > 0) {
146                 /*
147                  * Tunable has successfully been changed from userland
148                  */
149                 int *data = get_ipc(table);
150
151                 tunable_set_callback(*data);
152         }
153
154         return rc;
155 }
156 #else
157 #define sysctl_ipc_data NULL
158 #define sysctl_ipc_registered_data NULL
159 #endif
160
161 static struct ctl_table ipc_kern_table[] = {
162         {
163                 .ctl_name       = KERN_SHMMAX,
164                 .procname       = "shmmax",
165                 .data           = &init_ipc_ns.shm_ctlmax,
166                 .maxlen         = sizeof (init_ipc_ns.shm_ctlmax),
167                 .mode           = 0644,
168                 .proc_handler   = proc_ipc_doulongvec_minmax,
169                 .strategy       = sysctl_ipc_data,
170         },
171         {
172                 .ctl_name       = KERN_SHMALL,
173                 .procname       = "shmall",
174                 .data           = &init_ipc_ns.shm_ctlall,
175                 .maxlen         = sizeof (init_ipc_ns.shm_ctlall),
176                 .mode           = 0644,
177                 .proc_handler   = proc_ipc_doulongvec_minmax,
178                 .strategy       = sysctl_ipc_data,
179         },
180         {
181                 .ctl_name       = KERN_SHMMNI,
182                 .procname       = "shmmni",
183                 .data           = &init_ipc_ns.shm_ctlmni,
184                 .maxlen         = sizeof (init_ipc_ns.shm_ctlmni),
185                 .mode           = 0644,
186                 .proc_handler   = proc_ipc_dointvec,
187                 .strategy       = sysctl_ipc_data,
188         },
189         {
190                 .ctl_name       = KERN_MSGMAX,
191                 .procname       = "msgmax",
192                 .data           = &init_ipc_ns.msg_ctlmax,
193                 .maxlen         = sizeof (init_ipc_ns.msg_ctlmax),
194                 .mode           = 0644,
195                 .proc_handler   = proc_ipc_dointvec,
196                 .strategy       = sysctl_ipc_data,
197         },
198         {
199                 .ctl_name       = KERN_MSGMNI,
200                 .procname       = "msgmni",
201                 .data           = &init_ipc_ns.msg_ctlmni,
202                 .maxlen         = sizeof (init_ipc_ns.msg_ctlmni),
203                 .mode           = 0644,
204                 .proc_handler   = proc_ipc_callback_dointvec,
205                 .strategy       = sysctl_ipc_registered_data,
206         },
207         {
208                 .ctl_name       = KERN_MSGMNB,
209                 .procname       =  "msgmnb",
210                 .data           = &init_ipc_ns.msg_ctlmnb,
211                 .maxlen         = sizeof (init_ipc_ns.msg_ctlmnb),
212                 .mode           = 0644,
213                 .proc_handler   = proc_ipc_dointvec,
214                 .strategy       = sysctl_ipc_data,
215         },
216         {
217                 .ctl_name       = KERN_SEM,
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                 .strategy       = sysctl_ipc_data,
224         },
225         {}
226 };
227
228 static struct ctl_table ipc_root_table[] = {
229         {
230                 .ctl_name       = CTL_KERN,
231                 .procname       = "kernel",
232                 .mode           = 0555,
233                 .child          = ipc_kern_table,
234         },
235         {}
236 };
237
238 static int __init ipc_sysctl_init(void)
239 {
240         register_sysctl_table(ipc_root_table);
241         return 0;
242 }
243
244 __initcall(ipc_sysctl_init);