linux/ipc/mq_sysctl.c
Alexey Gladkov dc55e35f9e ipc: Store mqueue sysctls in the ipc namespace
Right now, the mqueue sysctls take ipc namespaces into account in a
rather hacky way. This works in most cases, but does not respect the
user namespace.

Within the user namespace, the user cannot change the /proc/sys/fs/mqueue/*
parametres. This poses a problem in the rootless containers.

To solve this I changed the implementation of the mqueue sysctls just
like some other sysctls.

So far, the changes do not provide additional access to files. This will
be done in a future patch.

v3:
* Don't implemenet set_permissions to keep the current behavior.

v2:
* Fixed compilation problem if CONFIG_POSIX_MQUEUE_SYSCTL is not
  specified.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Alexey Gladkov <legion@kernel.org>
Link: https://lkml.kernel.org/r/b0ccbb2489119f1f20c737cf1930c3a9c4e4243a.1644862280.git.legion@kernel.org
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2022-03-08 13:39:40 -06:00

132 lines
3.0 KiB
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>
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 &current->nsproxy->ipc_ns->mq_set;
}
static int set_is_seen(struct ctl_table_set *set)
{
return &current->nsproxy->ipc_ns->mq_set == set;
}
static struct ctl_table_root set_root = {
.lookup = set_lookup,
};
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);
}
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);
}