Root/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
21static 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
30static 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
41static 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
52static 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
65static 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
88static 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 */
108static 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
122static 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
159static int zero;
160static int one = 1;
161
162static struct ctl_table ipc_kern_table[] = {
163    {
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    },
170    {
171        .procname = "shmall",
172        .data = &init_ipc_ns.shm_ctlall,
173        .maxlen = sizeof (init_ipc_ns.shm_ctlall),
174        .mode = 0644,
175        .proc_handler = proc_ipc_doulongvec_minmax,
176    },
177    {
178        .procname = "shmmni",
179        .data = &init_ipc_ns.shm_ctlmni,
180        .maxlen = sizeof (init_ipc_ns.shm_ctlmni),
181        .mode = 0644,
182        .proc_handler = proc_ipc_dointvec,
183    },
184    {
185        .procname = "shm_rmid_forced",
186        .data = &init_ipc_ns.shm_rmid_forced,
187        .maxlen = sizeof(init_ipc_ns.shm_rmid_forced),
188        .mode = 0644,
189        .proc_handler = proc_ipc_dointvec_minmax_orphans,
190        .extra1 = &zero,
191        .extra2 = &one,
192    },
193    {
194        .procname = "msgmax",
195        .data = &init_ipc_ns.msg_ctlmax,
196        .maxlen = sizeof (init_ipc_ns.msg_ctlmax),
197        .mode = 0644,
198        .proc_handler = proc_ipc_dointvec,
199    },
200    {
201        .procname = "msgmni",
202        .data = &init_ipc_ns.msg_ctlmni,
203        .maxlen = sizeof (init_ipc_ns.msg_ctlmni),
204        .mode = 0644,
205        .proc_handler = proc_ipc_callback_dointvec,
206    },
207    {
208        .procname = "msgmnb",
209        .data = &init_ipc_ns.msg_ctlmnb,
210        .maxlen = sizeof (init_ipc_ns.msg_ctlmnb),
211        .mode = 0644,
212        .proc_handler = proc_ipc_dointvec,
213    },
214    {
215        .procname = "sem",
216        .data = &init_ipc_ns.sem_ctls,
217        .maxlen = 4*sizeof (int),
218        .mode = 0644,
219        .proc_handler = proc_ipc_dointvec,
220    },
221    {
222        .procname = "auto_msgmni",
223        .data = &init_ipc_ns.auto_msgmni,
224        .maxlen = sizeof(int),
225        .mode = 0644,
226        .proc_handler = proc_ipcauto_dointvec_minmax,
227        .extra1 = &zero,
228        .extra2 = &one,
229    },
230    {}
231};
232
233static struct ctl_table ipc_root_table[] = {
234    {
235        .procname = "kernel",
236        .mode = 0555,
237        .child = ipc_kern_table,
238    },
239    {}
240};
241
242static int __init ipc_sysctl_init(void)
243{
244    register_sysctl_table(ipc_root_table);
245    return 0;
246}
247
248__initcall(ipc_sysctl_init);
249

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