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 static struct ctl_table_set *set_lookup(struct ctl_table_root *root)
  70 {
  71         return &current->nsproxy->ipc_ns->mq_set;
  72 }
  73
  74 static int set_is_seen(struct ctl_table_set *set)
  75 {
  76         return &current->nsproxy->ipc_ns->mq_set == set;
  77 }
  78
  79 static void mq_set_ownership(struct ctl_table_header *head,
  80                              kuid_t *uid, kgid_t *gid)
  81 {
  82         struct ipc_namespace *ns =
  83                 container_of(head->set, struct ipc_namespace, mq_set);
  84
  85         kuid_t ns_root_uid = make_kuid(ns->user_ns, 0);
  86         kgid_t ns_root_gid = make_kgid(ns->user_ns, 0);
  87
  88         *uid = uid_valid(ns_root_uid) ? ns_root_uid : GLOBAL_ROOT_UID;
  89         *gid = gid_valid(ns_root_gid) ? ns_root_gid : GLOBAL_ROOT_GID;
  90 }
  91
  92 static int mq_permissions(struct ctl_table_header *head, const struct ctl_table *table)
  93 {
  94         int mode = table->mode;
  95         kuid_t ns_root_uid;
  96         kgid_t ns_root_gid;
  97
  98         mq_set_ownership(head, &ns_root_uid, &ns_root_gid);
  99
 100         if (uid_eq(current_euid(), ns_root_uid))
 101                 mode >>= 6;
 102
 103         else if (in_egroup_p(ns_root_gid))
 104                 mode >>= 3;
 105
 106         mode &= 7;
 107
 108         return (mode << 6) | (mode << 3) | mode;
 109 }
 110
 111 static struct ctl_table_root set_root = {
 112         .lookup = set_lookup,
 113         .permissions = mq_permissions,
 114         .set_ownership = mq_set_ownership,
 115 };
 116
 117 bool setup_mq_sysctls(struct ipc_namespace *ns)
 118 {
 119         struct ctl_table *tbl;
 120
 121         setup_sysctl_set(&ns->mq_set, &set_root, set_is_seen);
 122
 123         tbl = kmemdup(mq_sysctls, sizeof(mq_sysctls), GFP_KERNEL);
 124         if (tbl) {
 125                 int i;
 126
 127                 for (i = 0; i < ARRAY_SIZE(mq_sysctls); i++) {
 128                         if (tbl[i].data == &init_ipc_ns.mq_queues_max)
 129                                 tbl[i].data = &ns->mq_queues_max;
 130
 131                         else if (tbl[i].data == &init_ipc_ns.mq_msg_max)
 132                                 tbl[i].data = &ns->mq_msg_max;
 133
 134                         else if (tbl[i].data == &init_ipc_ns.mq_msgsize_max)
 135                                 tbl[i].data = &ns->mq_msgsize_max;
 136
 137                         else if (tbl[i].data == &init_ipc_ns.mq_msg_default)
 138                                 tbl[i].data = &ns->mq_msg_default;
 139
 140                         else if (tbl[i].data == &init_ipc_ns.mq_msgsize_default)
 141                                 tbl[i].data = &ns->mq_msgsize_default;
 142                         else
 143                                 tbl[i].data = NULL;
 144                 }
 145
 146                 ns->mq_sysctls = __register_sysctl_table(&ns->mq_set,
 147                                                          "fs/mqueue", tbl,
 148                                                          ARRAY_SIZE(mq_sysctls));
 149         }
 150         if (!ns->mq_sysctls) {
 151                 kfree(tbl);
 152                 retire_sysctl_set(&ns->mq_set);
 153                 return false;
 154         }
 155
 156         return true;
 157 }
 158
 159 void retire_mq_sysctls(struct ipc_namespace *ns)
 160 {
 161         const struct ctl_table *tbl;
 162
 163         tbl = ns->mq_sysctls->ctl_table_arg;
 164         unregister_sysctl_table(ns->mq_sysctls);
 165         retire_sysctl_set(&ns->mq_set);
 166         kfree(tbl);
 167 }