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 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
70static struct ctl_table_set *set_lookup(struct ctl_table_root *root)
71{
72	return &current->nsproxy->ipc_ns->mq_set;
73}
74
75static int set_is_seen(struct ctl_table_set *set)
76{
77	return &current->nsproxy->ipc_ns->mq_set == set;
78}
79
80static void mq_set_ownership(struct ctl_table_header *head,
81			     struct ctl_table *table,
82			     kuid_t *uid, kgid_t *gid)
83{
84	struct ipc_namespace *ns =
85		container_of(head->set, struct ipc_namespace, mq_set);
86
87	kuid_t ns_root_uid = make_kuid(ns->user_ns, 0);
88	kgid_t ns_root_gid = make_kgid(ns->user_ns, 0);
89
90	*uid = uid_valid(ns_root_uid) ? ns_root_uid : GLOBAL_ROOT_UID;
91	*gid = gid_valid(ns_root_gid) ? ns_root_gid : GLOBAL_ROOT_GID;
92}
93
94static int mq_permissions(struct ctl_table_header *head, struct ctl_table *table)
95{
96	int mode = table->mode;
97	kuid_t ns_root_uid;
98	kgid_t ns_root_gid;
99
100	mq_set_ownership(head, table, &ns_root_uid, &ns_root_gid);
101
102	if (uid_eq(current_euid(), ns_root_uid))
103		mode >>= 6;
104
105	else if (in_egroup_p(ns_root_gid))
106		mode >>= 3;
107
108	mode &= 7;
109
110	return (mode << 6) | (mode << 3) | mode;
111}
112
113static struct ctl_table_root set_root = {
114	.lookup = set_lookup,
115	.permissions = mq_permissions,
116	.set_ownership = mq_set_ownership,
117};
118
119bool setup_mq_sysctls(struct ipc_namespace *ns)
120{
121	struct ctl_table *tbl;
122
123	setup_sysctl_set(&ns->mq_set, &set_root, set_is_seen);
124
125	tbl = kmemdup(mq_sysctls, sizeof(mq_sysctls), GFP_KERNEL);
126	if (tbl) {
127		int i;
128
129		for (i = 0; i < ARRAY_SIZE(mq_sysctls); i++) {
130			if (tbl[i].data == &init_ipc_ns.mq_queues_max)
131				tbl[i].data = &ns->mq_queues_max;
132
133			else if (tbl[i].data == &init_ipc_ns.mq_msg_max)
134				tbl[i].data = &ns->mq_msg_max;
135
136			else if (tbl[i].data == &init_ipc_ns.mq_msgsize_max)
137				tbl[i].data = &ns->mq_msgsize_max;
138
139			else if (tbl[i].data == &init_ipc_ns.mq_msg_default)
140				tbl[i].data = &ns->mq_msg_default;
141
142			else if (tbl[i].data == &init_ipc_ns.mq_msgsize_default)
143				tbl[i].data = &ns->mq_msgsize_default;
144			else
145				tbl[i].data = NULL;
146		}
147
148		ns->mq_sysctls = __register_sysctl_table(&ns->mq_set,
149							 "fs/mqueue", tbl,
150							 ARRAY_SIZE(mq_sysctls));
151	}
152	if (!ns->mq_sysctls) {
153		kfree(tbl);
154		retire_sysctl_set(&ns->mq_set);
155		return false;
156	}
157
158	return true;
159}
160
161void retire_mq_sysctls(struct ipc_namespace *ns)
162{
163	struct ctl_table *tbl;
164
165	tbl = ns->mq_sysctls->ctl_table_arg;
166	unregister_sysctl_table(ns->mq_sysctls);
167	retire_sysctl_set(&ns->mq_set);
168	kfree(tbl);
169}
170