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);