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(struct 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(struct 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(struct 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(struct 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_minmax(struct 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_minmax(&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(struct 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(struct ctl_table *table, int write,
 123         void __user *buffer, size_t *lenp, loff_t *ppos)
 124 {
 125         struct ctl_table ipc_table;
 126         int oldval;
 127         int rc;
 128
 129         memcpy(&ipc_table, table, sizeof(ipc_table));
 130         ipc_table.data = get_ipc(table);
 131         oldval = *((int *)(ipc_table.data));
 132
 133         rc = proc_dointvec_minmax(&ipc_table, write, buffer, lenp, ppos);
 134
 135         if (write && !rc) {
 136                 int newval = *((int *)(ipc_table.data));
 137                 /*
 138                  * The file "auto_msgmni" has correctly been set.
 139                  * React by (un)registering the corresponding tunable, if the
 140                  * value has changed.
 141                  */
 142                 if (newval != oldval)
 143                         ipc_auto_callback(newval);
 144         }
 145
 146         return rc;
 147 }
 148
 149 #else
 150 #define proc_ipc_doulongvec_minmax NULL
 151 #define proc_ipc_dointvec          NULL
 152 #define proc_ipc_dointvec_minmax   NULL
 153 #define proc_ipc_dointvec_minmax_orphans   NULL
 154 #define proc_ipc_callback_dointvec_minmax  NULL
 155 #define proc_ipcauto_dointvec_minmax NULL
 156 #endif
 157
 158 static int zero;
 159 static int one = 1;
 160 static int int_max = INT_MAX;
 161
 162 static 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_minmax,
 199                 .extra1         = &zero,
 200                 .extra2         = &int_max,
 201         },
 202         {
 203                 .procname       = "msgmni",
 204                 .data           = &init_ipc_ns.msg_ctlmni,
 205                 .maxlen         = sizeof(init_ipc_ns.msg_ctlmni),
 206                 .mode           = 0644,
 207                 .proc_handler   = proc_ipc_callback_dointvec_minmax,
 208                 .extra1         = &zero,
 209                 .extra2         = &int_max,
 210         },
 211         {
 212                 .procname       =  "msgmnb",
 213                 .data           = &init_ipc_ns.msg_ctlmnb,
 214                 .maxlen         = sizeof(init_ipc_ns.msg_ctlmnb),
 215                 .mode           = 0644,
 216                 .proc_handler   = proc_ipc_dointvec_minmax,
 217                 .extra1         = &zero,
 218                 .extra2         = &int_max,
 219         },
 220         {
 221                 .procname       = "sem",
 222                 .data           = &init_ipc_ns.sem_ctls,
 223                 .maxlen         = 4*sizeof(int),
 224                 .mode           = 0644,
 225                 .proc_handler   = proc_ipc_dointvec,
 226         },
 227         {
 228                 .procname       = "auto_msgmni",
 229                 .data           = &init_ipc_ns.auto_msgmni,
 230                 .maxlen         = sizeof(int),
 231                 .mode           = 0644,
 232                 .proc_handler   = proc_ipcauto_dointvec_minmax,
 233                 .extra1         = &zero,
 234                 .extra2         = &one,
 235         },
 236 #ifdef CONFIG_CHECKPOINT_RESTORE
 237         {
 238                 .procname       = "sem_next_id",
 239                 .data           = &init_ipc_ns.ids[IPC_SEM_IDS].next_id,
 240                 .maxlen         = sizeof(init_ipc_ns.ids[IPC_SEM_IDS].next_id),
 241                 .mode           = 0644,
 242                 .proc_handler   = proc_ipc_dointvec_minmax,
 243                 .extra1         = &zero,
 244                 .extra2         = &int_max,
 245         },
 246         {
 247                 .procname       = "msg_next_id",
 248                 .data           = &init_ipc_ns.ids[IPC_MSG_IDS].next_id,
 249                 .maxlen         = sizeof(init_ipc_ns.ids[IPC_MSG_IDS].next_id),
 250                 .mode           = 0644,
 251                 .proc_handler   = proc_ipc_dointvec_minmax,
 252                 .extra1         = &zero,
 253                 .extra2         = &int_max,
 254         },
 255         {
 256                 .procname       = "shm_next_id",
 257                 .data           = &init_ipc_ns.ids[IPC_SHM_IDS].next_id,
 258                 .maxlen         = sizeof(init_ipc_ns.ids[IPC_SHM_IDS].next_id),
 259                 .mode           = 0644,
 260                 .proc_handler   = proc_ipc_dointvec_minmax,
 261                 .extra1         = &zero,
 262                 .extra2         = &int_max,
 263         },
 264 #endif
 265         {}
 266 };
 267
 268 static struct ctl_table ipc_root_table[] = {
 269         {
 270                 .procname       = "kernel",
 271                 .mode           = 0555,
 272                 .child          = ipc_kern_table,
 273         },
 274         {}
 275 };
 276
 277 static int __init ipc_sysctl_init(void)
 278 {
 279         register_sysctl_table(ipc_root_table);
 280         return 0;
 281 }
 282
 283 device_initcall(ipc_sysctl_init);