Quellverzeichnis mq_sysctl.c Sprache: C

// SPDX-License-Identifier: GPL-2.0-only
/*
*  Copyright (C) 2007 IBM Corporation
*
*  Author: Cedric Le Goater <clg@fr.ibm.com>
*/

#include <linux/nsproxy.h>
#include <linux/ipc_namespace.h>
#include <linux/sysctl.h>

#include <linux/stat.h>
#include <linux/capability.h>
#include <linux/slab.h>
#include <linux/cred.h>

static int msg_max_limit_min = MIN_MSGMAX;
static int msg_max_limit_max = HARD_MSGMAX;

static int msg_maxsize_limit_min = MIN_MSGSIZEMAX;
static int msg_maxsize_limit_max = HARD_MSGSIZEMAX;

static const struct ctl_table mq_sysctls[] = {
{
  .procname = "queues_max",
  .data  = &init_ipc_ns.mq_queues_max,
  .maxlen  = sizeof(int),
  .mode  = 0644,
  .proc_handler = proc_dointvec,
},
{
  .procname = "msg_max",
  .data  = &init_ipc_ns.mq_msg_max,
  .maxlen  = sizeof(int),
  .mode  = 0644,
  .proc_handler = proc_dointvec_minmax,
  .extra1  = &msg_max_limit_min,
  .extra2  = &msg_max_limit_max,
},
{
  .procname = "msgsize_max",
  .data  = &init_ipc_ns.mq_msgsize_max,
  .maxlen  = sizeof(int),
  .mode  = 0644,
  .proc_handler = proc_dointvec_minmax,
  .extra1  = &msg_maxsize_limit_min,
  .extra2  = &msg_maxsize_limit_max,
},
{
  .procname = "msg_default",
  .data  = &init_ipc_ns.mq_msg_default,
  .maxlen  = sizeof(int),
  .mode  = 0644,
  .proc_handler = proc_dointvec_minmax,
  .extra1  = &msg_max_limit_min,
  .extra2  = &msg_max_limit_max,
},
{
  .procname = "msgsize_default",
  .data  = &init_ipc_ns.mq_msgsize_default,
  .maxlen  = sizeof(int),
  .mode  = 0644,
  .proc_handler = proc_dointvec_minmax,
  .extra1  = &msg_maxsize_limit_min,
  .extra2  = &msg_maxsize_limit_max,
},
};

static struct ctl_table_set *set_lookup(struct ctl_table_root *root)
{
return ¤t->nsproxy->ipc_ns->mq_set;
}

static int set_is_seen(struct ctl_table_set *set)
{
return ¤t->nsproxy->ipc_ns->mq_set == set;
}

static void mq_set_ownership(struct ctl_table_header *head,
        kuid_t *uid, kgid_t *gid)
{
struct ipc_namespace *ns =
  container_of(head->set, struct ipc_namespace, mq_set);

kuid_t ns_root_uid = make_kuid(ns->user_ns, 0);
kgid_t ns_root_gid = make_kgid(ns->user_ns, 0);

*uid = uid_valid(ns_root_uid) ? ns_root_uid : GLOBAL_ROOT_UID;
*gid = gid_valid(ns_root_gid) ? ns_root_gid : GLOBAL_ROOT_GID;
}

static int mq_permissions(struct ctl_table_header *head, const struct ctl_table *table)
{
int mode = table->mode;
kuid_t ns_root_uid;
kgid_t ns_root_gid;

mq_set_ownership(head, &ns_root_uid, &ns_root_gid);

if (uid_eq(current_euid(), ns_root_uid))
  mode >>= 6;

else if (in_egroup_p(ns_root_gid))
  mode >>= 3;

mode &= 7;

return (mode << 6) | (mode << 3) | mode;
}

static struct ctl_table_root set_root = {
.lookup = set_lookup,
.permissions = mq_permissions,
.set_ownership = mq_set_ownership,
};

bool setup_mq_sysctls(struct ipc_namespace *ns)
{
struct ctl_table *tbl;

setup_sysctl_set(&ns->mq_set, &set_root, set_is_seen);

tbl = kmemdup(mq_sysctls, sizeof(mq_sysctls), GFP_KERNEL);
if (tbl) {
  int i;

  for (i = 0; i < ARRAY_SIZE(mq_sysctls); i++) {
   if (tbl[i].data == &init_ipc_ns.mq_queues_max)
    tbl[i].data = &ns->mq_queues_max;

   else if (tbl[i].data == &init_ipc_ns.mq_msg_max)
    tbl[i].data = &ns->mq_msg_max;

   else if (tbl[i].data == &init_ipc_ns.mq_msgsize_max)
    tbl[i].data = &ns->mq_msgsize_max;

   else if (tbl[i].data == &init_ipc_ns.mq_msg_default)
    tbl[i].data = &ns->mq_msg_default;

   else if (tbl[i].data == &init_ipc_ns.mq_msgsize_default)
    tbl[i].data = &ns->mq_msgsize_default;
   else
    tbl[i].data = NULL;
  }

  ns->mq_sysctls = __register_sysctl_table(&ns->mq_set,
        "fs/mqueue", tbl,
        ARRAY_SIZE(mq_sysctls));
}
if (!ns->mq_sysctls) {
  kfree(tbl);
  retire_sysctl_set(&ns->mq_set);
  return false;
}

return true;
}

void retire_mq_sysctls(struct ipc_namespace *ns)
{
const struct ctl_table *tbl;

tbl = ns->mq_sysctls->ctl_table_arg;
unregister_sysctl_table(ns->mq_sysctls);
retire_sysctl_set(&ns->mq_set);
kfree(tbl);
}

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