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 #ifdef CONFIG_PROC_SYSCTL
  30 static 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
  41 static 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
  52 static 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
  65 static 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
  88 static 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  */
 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(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
 159 static int zero;
 160 static int one = 1;
 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,
 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
 233 static struct ctl_table ipc_root_table[] = {
 234         {
 235                 .procname       = "kernel",
 236                 .mode           = 0555,
 237                 .child          = ipc_kern_table,
 238         },
 239         {}
 240 };
 241
 242 static int __init ipc_sysctl_init(void)
 243 {
 244         register_sysctl_table(ipc_root_table);
 245         return 0;
 246 }
 247
 248 __initcall(ipc_sysctl_init);