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167 lines · 3.9 KiB

1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2007 IBM Corporation
4 *
5 * Author: Cedric Le Goater <[email protected]>
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}