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mq_sysctl.c
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mq_sysctl.c
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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2007 IBM Corporation
*
* Author: Cedric Le Goater <[email protected]>
*/
#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 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,
struct ctl_table *table,
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, struct ctl_table *table)
{
int mode = table->mode;
kuid_t ns_root_uid;
kgid_t ns_root_gid;
mq_set_ownership(head, table, &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)
{
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);
}