1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
|
// SPDX-License-Identifier: GPL-2.0-only
/*
* Landlock - Network management and hooks
*
* Copyright © 2022-2023 Huawei Tech. Co., Ltd.
* Copyright © 2022-2025 Microsoft Corporation
*/
#include <linux/in.h>
#include <linux/lsm_audit.h>
#include <linux/net.h>
#include <linux/socket.h>
#include <net/ipv6.h>
#include "audit.h"
#include "common.h"
#include "cred.h"
#include "limits.h"
#include "net.h"
#include "ruleset.h"
int landlock_append_net_rule(struct landlock_ruleset *const ruleset,
const u16 port, access_mask_t access_rights)
{
int err;
const struct landlock_id id = {
.key.data = (__force uintptr_t)htons(port),
.type = LANDLOCK_KEY_NET_PORT,
};
BUILD_BUG_ON(sizeof(port) > sizeof(id.key.data));
/* Transforms relative access rights to absolute ones. */
access_rights |= LANDLOCK_MASK_ACCESS_NET &
~landlock_get_net_access_mask(ruleset, 0);
mutex_lock(&ruleset->lock);
err = landlock_insert_rule(ruleset, id, access_rights);
mutex_unlock(&ruleset->lock);
return err;
}
static int current_check_access_socket(struct socket *const sock,
struct sockaddr *const address,
const int addrlen,
access_mask_t access_request)
{
__be16 port;
layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_NET] = {};
const struct landlock_rule *rule;
struct landlock_id id = {
.type = LANDLOCK_KEY_NET_PORT,
};
const struct access_masks masks = {
.net = access_request,
};
const struct landlock_cred_security *const subject =
landlock_get_applicable_subject(current_cred(), masks, NULL);
struct lsm_network_audit audit_net = {};
if (!subject)
return 0;
if (!sk_is_tcp(sock->sk))
return 0;
/* Checks for minimal header length to safely read sa_family. */
if (addrlen < offsetofend(typeof(*address), sa_family))
return -EINVAL;
switch (address->sa_family) {
case AF_UNSPEC:
case AF_INET: {
const struct sockaddr_in *addr4;
if (addrlen < sizeof(struct sockaddr_in))
return -EINVAL;
addr4 = (struct sockaddr_in *)address;
port = addr4->sin_port;
if (access_request == LANDLOCK_ACCESS_NET_CONNECT_TCP) {
audit_net.dport = port;
audit_net.v4info.daddr = addr4->sin_addr.s_addr;
} else if (access_request == LANDLOCK_ACCESS_NET_BIND_TCP) {
audit_net.sport = port;
audit_net.v4info.saddr = addr4->sin_addr.s_addr;
} else {
WARN_ON_ONCE(1);
}
break;
}
#if IS_ENABLED(CONFIG_IPV6)
case AF_INET6: {
const struct sockaddr_in6 *addr6;
if (addrlen < SIN6_LEN_RFC2133)
return -EINVAL;
addr6 = (struct sockaddr_in6 *)address;
port = addr6->sin6_port;
if (access_request == LANDLOCK_ACCESS_NET_CONNECT_TCP) {
audit_net.dport = port;
audit_net.v6info.daddr = addr6->sin6_addr;
} else if (access_request == LANDLOCK_ACCESS_NET_BIND_TCP) {
audit_net.sport = port;
audit_net.v6info.saddr = addr6->sin6_addr;
} else {
WARN_ON_ONCE(1);
}
break;
}
#endif /* IS_ENABLED(CONFIG_IPV6) */
default:
return 0;
}
/* Specific AF_UNSPEC handling. */
if (address->sa_family == AF_UNSPEC) {
/*
* Connecting to an address with AF_UNSPEC dissolves the TCP
* association, which have the same effect as closing the
* connection while retaining the socket object (i.e., the file
* descriptor). As for dropping privileges, closing
* connections is always allowed.
*
* For a TCP access control system, this request is legitimate.
* Let the network stack handle potential inconsistencies and
* return -EINVAL if needed.
*/
if (access_request == LANDLOCK_ACCESS_NET_CONNECT_TCP)
return 0;
/*
* For compatibility reason, accept AF_UNSPEC for bind
* accesses (mapped to AF_INET) only if the address is
* INADDR_ANY (cf. __inet_bind). Checking the address is
* required to not wrongfully return -EACCES instead of
* -EAFNOSUPPORT.
*
* We could return 0 and let the network stack handle these
* checks, but it is safer to return a proper error and test
* consistency thanks to kselftest.
*/
if (access_request == LANDLOCK_ACCESS_NET_BIND_TCP) {
/* addrlen has already been checked for AF_UNSPEC. */
const struct sockaddr_in *const sockaddr =
(struct sockaddr_in *)address;
if (sock->sk->__sk_common.skc_family != AF_INET)
return -EINVAL;
if (sockaddr->sin_addr.s_addr != htonl(INADDR_ANY))
return -EAFNOSUPPORT;
}
} else {
/*
* Checks sa_family consistency to not wrongfully return
* -EACCES instead of -EINVAL. Valid sa_family changes are
* only (from AF_INET or AF_INET6) to AF_UNSPEC.
*
* We could return 0 and let the network stack handle this
* check, but it is safer to return a proper error and test
* consistency thanks to kselftest.
*/
if (address->sa_family != sock->sk->__sk_common.skc_family)
return -EINVAL;
}
id.key.data = (__force uintptr_t)port;
BUILD_BUG_ON(sizeof(port) > sizeof(id.key.data));
rule = landlock_find_rule(subject->domain, id);
access_request = landlock_init_layer_masks(subject->domain,
access_request, &layer_masks,
LANDLOCK_KEY_NET_PORT);
if (landlock_unmask_layers(rule, access_request, &layer_masks,
ARRAY_SIZE(layer_masks)))
return 0;
audit_net.family = address->sa_family;
landlock_log_denial(subject,
&(struct landlock_request){
.type = LANDLOCK_REQUEST_NET_ACCESS,
.audit.type = LSM_AUDIT_DATA_NET,
.audit.u.net = &audit_net,
.access = access_request,
.layer_masks = &layer_masks,
.layer_masks_size = ARRAY_SIZE(layer_masks),
});
return -EACCES;
}
static int hook_socket_bind(struct socket *const sock,
struct sockaddr *const address, const int addrlen)
{
return current_check_access_socket(sock, address, addrlen,
LANDLOCK_ACCESS_NET_BIND_TCP);
}
static int hook_socket_connect(struct socket *const sock,
struct sockaddr *const address,
const int addrlen)
{
return current_check_access_socket(sock, address, addrlen,
LANDLOCK_ACCESS_NET_CONNECT_TCP);
}
static struct security_hook_list landlock_hooks[] __ro_after_init = {
LSM_HOOK_INIT(socket_bind, hook_socket_bind),
LSM_HOOK_INIT(socket_connect, hook_socket_connect),
};
__init void landlock_add_net_hooks(void)
{
security_add_hooks(landlock_hooks, ARRAY_SIZE(landlock_hooks),
&landlock_lsmid);
}
|
