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 the file "auto_msgmni" has successfully been
  31  * written.
  32  * Two values are allowed:
  33  * 0: unregister msgmni's callback routine from the ipc namespace notifier
  34  *    chain. This means that msgmni won't be recomputed anymore upon memory
  35  *    add/remove or ipc namespace creation/removal.
  36  * 1: register back the callback routine.
  37  */
  38 static void ipc_auto_callback(int val)
  39 {
  40         if (!val)
  41                 unregister_ipcns_notifier(current->nsproxy->ipc_ns);
  42         else {
  43                 /*
  44                  * Re-enable automatic recomputing only if not already
  45                  * enabled.
  46                  */
  47                 recompute_msgmni(current->nsproxy->ipc_ns);
  48                 cond_register_ipcns_notifier(current->nsproxy->ipc_ns);
  49         }
  50 }
  51
  52 #ifdef CONFIG_PROC_FS
  53 static int proc_ipc_dointvec(ctl_table *table, int write, struct file *filp,
  54         void __user *buffer, size_t *lenp, loff_t *ppos)
  55 {
  56         struct ctl_table ipc_table;
  57         memcpy(&ipc_table, table, sizeof(ipc_table));
  58         ipc_table.data = get_ipc(table);
  59
  60         return proc_dointvec(&ipc_table, write, filp, buffer, lenp, ppos);
  61 }
  62
  63 static int proc_ipc_callback_dointvec(ctl_table *table, int write,
  64         struct file *filp, void __user *buffer, size_t *lenp, loff_t *ppos)
  65 {
  66         struct ctl_table ipc_table;
  67         size_t lenp_bef = *lenp;
  68         int rc;
  69
  70         memcpy(&ipc_table, table, sizeof(ipc_table));
  71         ipc_table.data = get_ipc(table);
  72
  73         rc = proc_dointvec(&ipc_table, write, filp, buffer, lenp, ppos);
  74
  75         if (write && !rc && lenp_bef == *lenp)
  76                 /*
  77                  * Tunable has successfully been changed by hand. Disable its
  78                  * automatic adjustment. This simply requires unregistering
  79                  * the notifiers that trigger recalculation.
  80                  */
  81                 unregister_ipcns_notifier(current->nsproxy->ipc_ns);
  82
  83         return rc;
  84 }
  85
  86 static int proc_ipc_doulongvec_minmax(ctl_table *table, int write,
  87         struct file *filp, void __user *buffer, size_t *lenp, loff_t *ppos)
  88 {
  89         struct ctl_table ipc_table;
  90         memcpy(&ipc_table, table, sizeof(ipc_table));
  91         ipc_table.data = get_ipc(table);
  92
  93         return proc_doulongvec_minmax(&ipc_table, write, filp, buffer,
  94                                         lenp, ppos);
  95 }
  96
  97 static int proc_ipcauto_dointvec_minmax(ctl_table *table, int write,
  98         struct file *filp, void __user *buffer, size_t *lenp, loff_t *ppos)
  99 {
 100         struct ctl_table ipc_table;
 101         size_t lenp_bef = *lenp;
 102         int oldval;
 103         int rc;
 104
 105         memcpy(&ipc_table, table, sizeof(ipc_table));
 106         ipc_table.data = get_ipc(table);
 107         oldval = *((int *)(ipc_table.data));
 108
 109         rc = proc_dointvec_minmax(&ipc_table, write, filp, buffer, lenp, ppos);
 110
 111         if (write && !rc && lenp_bef == *lenp) {
 112                 int newval = *((int *)(ipc_table.data));
 113                 /*
 114                  * The file "auto_msgmni" has correctly been set.
 115                  * React by (un)registering the corresponding tunable, if the
 116                  * value has changed.
 117                  */
 118                 if (newval != oldval)
 119                         ipc_auto_callback(newval);
 120         }
 121
 122         return rc;
 123 }
 124
 125 #else
 126 #define proc_ipc_doulongvec_minmax NULL
 127 #define proc_ipc_dointvec          NULL
 128 #define proc_ipc_callback_dointvec NULL
 129 #define proc_ipcauto_dointvec_minmax NULL
 130 #endif
 131
 132 #ifdef CONFIG_SYSCTL_SYSCALL
 133 /* The generic sysctl ipc data routine. */
 134 static int sysctl_ipc_data(ctl_table *table,
 135                 void __user *oldval, size_t __user *oldlenp,
 136                 void __user *newval, size_t newlen)
 137 {
 138         size_t len;
 139         void *data;
 140
 141         /* Get out of I don't have a variable */
 142         if (!table->data || !table->maxlen)
 143                 return -ENOTDIR;
 144
 145         data = get_ipc(table);
 146         if (!data)
 147                 return -ENOTDIR;
 148
 149         if (oldval && oldlenp) {
 150                 if (get_user(len, oldlenp))
 151                         return -EFAULT;
 152                 if (len) {
 153                         if (len > table->maxlen)
 154                                 len = table->maxlen;
 155                         if (copy_to_user(oldval, data, len))
 156                                 return -EFAULT;
 157                         if (put_user(len, oldlenp))
 158                                 return -EFAULT;
 159                 }
 160         }
 161
 162         if (newval && newlen) {
 163                 if (newlen > table->maxlen)
 164                         newlen = table->maxlen;
 165
 166                 if (copy_from_user(data, newval, newlen))
 167                         return -EFAULT;
 168         }
 169         return 1;
 170 }
 171
 172 static int sysctl_ipc_registered_data(ctl_table *table,
 173                 void __user *oldval, size_t __user *oldlenp,
 174                 void __user *newval, size_t newlen)
 175 {
 176         int rc;
 177
 178         rc = sysctl_ipc_data(table, oldval, oldlenp, newval, newlen);
 179
 180         if (newval && newlen && rc > 0)
 181                 /*
 182                  * Tunable has successfully been changed from userland
 183                  */
 184                 unregister_ipcns_notifier(current->nsproxy->ipc_ns);
 185
 186         return rc;
 187 }
 188 #else
 189 #define sysctl_ipc_data NULL
 190 #define sysctl_ipc_registered_data NULL
 191 #endif
 192
 193 static int zero;
 194 static int one = 1;
 195
 196 static struct ctl_table ipc_kern_table[] = {
 197         {
 198                 .ctl_name       = KERN_SHMMAX,
 199                 .procname       = "shmmax",
 200                 .data           = &init_ipc_ns.shm_ctlmax,
 201                 .maxlen         = sizeof (init_ipc_ns.shm_ctlmax),
 202                 .mode           = 0644,
 203                 .proc_handler   = proc_ipc_doulongvec_minmax,
 204                 .strategy       = sysctl_ipc_data,
 205         },
 206         {
 207                 .ctl_name       = KERN_SHMALL,
 208                 .procname       = "shmall",
 209                 .data           = &init_ipc_ns.shm_ctlall,
 210                 .maxlen         = sizeof (init_ipc_ns.shm_ctlall),
 211                 .mode           = 0644,
 212                 .proc_handler   = proc_ipc_doulongvec_minmax,
 213                 .strategy       = sysctl_ipc_data,
 214         },
 215         {
 216                 .ctl_name       = KERN_SHMMNI,
 217                 .procname       = "shmmni",
 218                 .data           = &init_ipc_ns.shm_ctlmni,
 219                 .maxlen         = sizeof (init_ipc_ns.shm_ctlmni),
 220                 .mode           = 0644,
 221                 .proc_handler   = proc_ipc_dointvec,
 222                 .strategy       = sysctl_ipc_data,
 223         },
 224         {
 225                 .ctl_name       = KERN_MSGMAX,
 226                 .procname       = "msgmax",
 227                 .data           = &init_ipc_ns.msg_ctlmax,
 228                 .maxlen         = sizeof (init_ipc_ns.msg_ctlmax),
 229                 .mode           = 0644,
 230                 .proc_handler   = proc_ipc_dointvec,
 231                 .strategy       = sysctl_ipc_data,
 232         },
 233         {
 234                 .ctl_name       = KERN_MSGMNI,
 235                 .procname       = "msgmni",
 236                 .data           = &init_ipc_ns.msg_ctlmni,
 237                 .maxlen         = sizeof (init_ipc_ns.msg_ctlmni),
 238                 .mode           = 0644,
 239                 .proc_handler   = proc_ipc_callback_dointvec,
 240                 .strategy       = sysctl_ipc_registered_data,
 241         },
 242         {
 243                 .ctl_name       = KERN_MSGMNB,
 244                 .procname       =  "msgmnb",
 245                 .data           = &init_ipc_ns.msg_ctlmnb,
 246                 .maxlen         = sizeof (init_ipc_ns.msg_ctlmnb),
 247                 .mode           = 0644,
 248                 .proc_handler   = proc_ipc_dointvec,
 249                 .strategy       = sysctl_ipc_data,
 250         },
 251         {
 252                 .ctl_name       = KERN_SEM,
 253                 .procname       = "sem",
 254                 .data           = &init_ipc_ns.sem_ctls,
 255                 .maxlen         = 4*sizeof (int),
 256                 .mode           = 0644,
 257                 .proc_handler   = proc_ipc_dointvec,
 258                 .strategy       = sysctl_ipc_data,
 259         },
 260         {
 261                 .ctl_name       = CTL_UNNUMBERED,
 262                 .procname       = "auto_msgmni",
 263                 .data           = &init_ipc_ns.auto_msgmni,
 264                 .maxlen         = sizeof(int),
 265                 .mode           = 0644,
 266                 .proc_handler   = proc_ipcauto_dointvec_minmax,
 267                 .extra1         = &zero,
 268                 .extra2         = &one,
 269         },
 270         {}
 271 };
 272
 273 static struct ctl_table ipc_root_table[] = {
 274         {
 275                 .ctl_name       = CTL_KERN,
 276                 .procname       = "kernel",
 277                 .mode           = 0555,
 278                 .child          = ipc_kern_table,
 279         },
 280         {}
 281 };
 282
 283 static int __init ipc_sysctl_init(void)
 284 {
 285         register_sysctl_table(ipc_root_table);
 286         return 0;
 287 }
 288
 289 __initcall(ipc_sysctl_init);