ipc/mq_sysctl.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  Copyright (C) 2007 IBM Corporation
   4  *
   5  *  Author: Cedric Le Goater <clg@fr.ibm.com>
   6  */
   7
   8 #include <linux/nsproxy.h>
   9 #include <linux/ipc_namespace.h>
  10 #include <linux/sysctl.h>
  11
  12 #include <linux/stat.h>
  13 #include <linux/capability.h>
  14 #include <linux/slab.h>
  15 #include <linux/cred.h>
  16
  17 static int msg_max_limit_min = MIN_MSGMAX;
  18 static int msg_max_limit_max = HARD_MSGMAX;
  19
  20 static int msg_maxsize_limit_min = MIN_MSGSIZEMAX;
  21 static int msg_maxsize_limit_max = HARD_MSGSIZEMAX;
  22
  23 static struct ctl_table mq_sysctls[] = {
  24         {
  25                 .procname       = "queues_max",
  26                 .data           = &init_ipc_ns.mq_queues_max,
  27                 .maxlen         = sizeof(int),
  28                 .mode           = 0644,
  29                 .proc_handler   = proc_dointvec,
  30         },
  31         {
  32                 .procname       = "msg_max",
  33                 .data           = &init_ipc_ns.mq_msg_max,
  34                 .maxlen         = sizeof(int),
  35                 .mode           = 0644,
  36                 .proc_handler   = proc_dointvec_minmax,
  37                 .extra1         = &msg_max_limit_min,
  38                 .extra2         = &msg_max_limit_max,
  39         },
  40         {
  41                 .procname       = "msgsize_max",
  42                 .data           = &init_ipc_ns.mq_msgsize_max,
  43                 .maxlen         = sizeof(int),
  44                 .mode           = 0644,
  45                 .proc_handler   = proc_dointvec_minmax,
  46                 .extra1         = &msg_maxsize_limit_min,
  47                 .extra2         = &msg_maxsize_limit_max,
  48         },
  49         {
  50                 .procname       = "msg_default",
  51                 .data           = &init_ipc_ns.mq_msg_default,
  52                 .maxlen         = sizeof(int),
  53                 .mode           = 0644,
  54                 .proc_handler   = proc_dointvec_minmax,
  55                 .extra1         = &msg_max_limit_min,
  56                 .extra2         = &msg_max_limit_max,
  57         },
  58         {
  59                 .procname       = "msgsize_default",
  60                 .data           = &init_ipc_ns.mq_msgsize_default,
  61                 .maxlen         = sizeof(int),
  62                 .mode           = 0644,
  63                 .proc_handler   = proc_dointvec_minmax,
  64                 .extra1         = &msg_maxsize_limit_min,
  65                 .extra2         = &msg_maxsize_limit_max,
  66         },
  67         {}
  68 };
  69
  70 static struct ctl_table_set *set_lookup(struct ctl_table_root *root)
  71 {
  72         return &current->nsproxy->ipc_ns->mq_set;
  73 }
  74
  75 static int set_is_seen(struct ctl_table_set *set)
  76 {
  77         return &current->nsproxy->ipc_ns->mq_set == set;
  78 }
  79
  80 static void mq_set_ownership(struct ctl_table_header *head,
  81                              struct ctl_table *table,
  82                              kuid_t *uid, kgid_t *gid)
  83 {
  84         struct ipc_namespace *ns =
  85                 container_of(head->set, struct ipc_namespace, mq_set);
  86
  87         kuid_t ns_root_uid = make_kuid(ns->user_ns, 0);
  88         kgid_t ns_root_gid = make_kgid(ns->user_ns, 0);
  89
  90         *uid = uid_valid(ns_root_uid) ? ns_root_uid : GLOBAL_ROOT_UID;
  91         *gid = gid_valid(ns_root_gid) ? ns_root_gid : GLOBAL_ROOT_GID;
  92 }
  93
  94 static int mq_permissions(struct ctl_table_header *head, struct ctl_table *table)
  95 {
  96         int mode = table->mode;
  97         kuid_t ns_root_uid;
  98         kgid_t ns_root_gid;
  99
 100         mq_set_ownership(head, table, &ns_root_uid, &ns_root_gid);
 101
 102         if (uid_eq(current_euid(), ns_root_uid))
 103                 mode >>= 6;
 104
 105         else if (in_egroup_p(ns_root_gid))
 106                 mode >>= 3;
 107
 108         mode &= 7;
 109
 110         return (mode << 6) | (mode << 3) | mode;
 111 }
 112
 113 static struct ctl_table_root set_root = {
 114         .lookup = set_lookup,
 115         .permissions = mq_permissions,
 116         .set_ownership = mq_set_ownership,
 117 };
 118
 119 bool setup_mq_sysctls(struct ipc_namespace *ns)
 120 {
 121         struct ctl_table *tbl;
 122
 123         setup_sysctl_set(&ns->mq_set, &set_root, set_is_seen);
 124
 125         tbl = kmemdup(mq_sysctls, sizeof(mq_sysctls), GFP_KERNEL);
 126         if (tbl) {
 127                 int i;
 128
 129                 for (i = 0; i < ARRAY_SIZE(mq_sysctls); i++) {
 130                         if (tbl[i].data == &init_ipc_ns.mq_queues_max)
 131                                 tbl[i].data = &ns->mq_queues_max;
 132
 133                         else if (tbl[i].data == &init_ipc_ns.mq_msg_max)
 134                                 tbl[i].data = &ns->mq_msg_max;
 135
 136                         else if (tbl[i].data == &init_ipc_ns.mq_msgsize_max)
 137                                 tbl[i].data = &ns->mq_msgsize_max;
 138
 139                         else if (tbl[i].data == &init_ipc_ns.mq_msg_default)
 140                                 tbl[i].data = &ns->mq_msg_default;
 141
 142                         else if (tbl[i].data == &init_ipc_ns.mq_msgsize_default)
 143                                 tbl[i].data = &ns->mq_msgsize_default;
 144                         else
 145                                 tbl[i].data = NULL;
 146                 }
 147
 148                 ns->mq_sysctls = __register_sysctl_table(&ns->mq_set,
 149                                                          "fs/mqueue", tbl,
 150                                                          ARRAY_SIZE(mq_sysctls));
 151         }
 152         if (!ns->mq_sysctls) {
 153                 kfree(tbl);
 154                 retire_sysctl_set(&ns->mq_set);
 155                 return false;
 156         }
 157
 158         return true;
 159 }
 160
 161 void retire_mq_sysctls(struct ipc_namespace *ns)
 162 {
 163         struct ctl_table *tbl;
 164
 165         tbl = ns->mq_sysctls->ctl_table_arg;
 166         unregister_sysctl_table(ns->mq_sysctls);
 167         retire_sysctl_set(&ns->mq_set);
 168         kfree(tbl);
 169 }