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
 17static int msg_max_limit_min = MIN_MSGMAX;
 18static int msg_max_limit_max = HARD_MSGMAX;
 19
 20static int msg_maxsize_limit_min = MIN_MSGSIZEMAX;
 21static int msg_maxsize_limit_max = HARD_MSGSIZEMAX;
 22
 23static const 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
 69static struct ctl_table_set *set_lookup(struct ctl_table_root *root)
 70{
 71	return &current->nsproxy->ipc_ns->mq_set;
 72}
 73
 74static int set_is_seen(struct ctl_table_set *set)
 75{
 76	return &current->nsproxy->ipc_ns->mq_set == set;
 77}
 78
 79static 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
 92static 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
111static struct ctl_table_root set_root = {
112	.lookup = set_lookup,
113	.permissions = mq_permissions,
114	.set_ownership = mq_set_ownership,
115};
116
117bool 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
159void 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}