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
|
/*
* Copyright (C) 2016 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#define LOG_TAG "keystore"
#include "permissions.h"
#include <cutils/sockets.h>
#include <log/log.h>
#include <private/android_filesystem_config.h>
#include <selinux/android.h>
#include "keystore_utils.h"
/* perm_labels associcated with keystore_key SELinux class verbs. */
const char* perm_labels[] = {
"get_state",
"get",
"insert",
"delete",
"exist",
"list",
"reset",
"password",
"lock",
"unlock",
"is_empty",
"sign",
"verify",
"grant",
"duplicate",
"clear_uid",
"add_auth",
"user_changed",
"gen_unique_id",
};
struct user_euid {
uid_t uid;
uid_t euid;
};
user_euid user_euids[] = {{AID_VPN, AID_SYSTEM},
{AID_WIFI, AID_SYSTEM},
{AID_ROOT, AID_SYSTEM},
{AID_FSVERITY_CERT, AID_ROOT},
{AID_FSVERITY_CERT, AID_SYSTEM},
#ifdef GRANT_ROOT_ALL_PERMISSIONS
// Allow VTS tests to act on behalf of the wifi user
{AID_WIFI, AID_ROOT}
#endif
};
struct user_perm {
uid_t uid;
perm_t perms;
};
static user_perm user_perms[] = {
{AID_SYSTEM, static_cast<perm_t>((uint32_t)(~0))},
{AID_VPN, static_cast<perm_t>(P_GET | P_SIGN | P_VERIFY)},
{AID_WIFI, static_cast<perm_t>(P_GET | P_SIGN | P_VERIFY)},
{AID_BLUETOOTH, static_cast<perm_t>(P_GET | P_INSERT | P_DELETE | P_EXIST | P_SIGN | P_VERIFY)},
#ifdef GRANT_ROOT_ALL_PERMISSIONS
// Allow VTS tests running as root to perform all operations
{AID_ROOT, static_cast<perm_t>((uint32_t)(~0))},
#else
{AID_ROOT, static_cast<perm_t>(P_GET)},
#endif
};
static const perm_t DEFAULT_PERMS = static_cast<perm_t>(
P_GET_STATE | P_GET | P_INSERT | P_DELETE | P_EXIST | P_LIST | P_SIGN | P_VERIFY |
P_GEN_UNIQUE_ID /* Only privileged apps can do this, but enforcement is done by SELinux */);
struct audit_data {
pid_t pid;
uid_t uid;
const char* sid;
};
const char* get_perm_label(perm_t perm) {
unsigned int index = ffs(perm);
if (index > 0 && index <= (sizeof(perm_labels) / sizeof(perm_labels[0]))) {
return perm_labels[index - 1];
} else {
ALOGE("Keystore: Failed to retrieve permission label.\n");
abort();
}
}
static int audit_callback(void* data, security_class_t /* cls */, char* buf, size_t len) {
struct audit_data* ad = reinterpret_cast<struct audit_data*>(data);
if (!ad) {
ALOGE("No keystore audit data");
return 0;
}
const char* sid = ad->sid ? ad->sid : "N/A";
snprintf(buf, len, "pid=%d uid=%d sid=%s", ad->pid, ad->uid, sid);
return 0;
}
static char* tctx;
int configure_selinux() {
union selinux_callback cb;
cb.func_audit = audit_callback;
selinux_set_callback(SELINUX_CB_AUDIT, cb);
cb.func_log = selinux_log_callback;
selinux_set_callback(SELINUX_CB_LOG, cb);
if (getcon(&tctx) != 0) {
ALOGE("SELinux: Could not acquire target context. Aborting keystore.\n");
return -1;
}
return 0;
}
static bool keystore_selinux_check_access(uid_t uid, perm_t perm, pid_t spid, const char* ssid) {
audit_data ad;
char* sctx = nullptr;
const char* selinux_class = "keystore_key";
const char* str_perm = get_perm_label(perm);
if (!str_perm) {
return false;
}
if (ssid == nullptr && getpidcon(spid, &sctx) != 0) {
ALOGE("SELinux: Failed to get source pid context.\n");
return false;
}
const char* use_sid = ssid ? ssid : sctx;
ad.pid = spid;
ad.uid = uid;
ad.sid = use_sid;
bool allowed = selinux_check_access(use_sid, tctx, selinux_class, str_perm,
reinterpret_cast<void*>(&ad)) == 0;
freecon(sctx);
return allowed;
}
/**
* Returns the UID that the callingUid should act as. This is here for
* legacy support of the WiFi and VPN systems and should be removed
* when WiFi can operate in its own namespace.
*/
uid_t get_keystore_euid(uid_t uid) {
for (size_t i = 0; i < sizeof(user_euids) / sizeof(user_euids[0]); i++) {
struct user_euid user = user_euids[i];
if (user.uid == uid) {
return user.euid;
}
}
return uid;
}
bool has_permission(uid_t uid, perm_t perm, pid_t spid, const char* sid) {
// All system users are equivalent for multi-user support.
if (get_app_id(uid) == AID_SYSTEM) {
uid = AID_SYSTEM;
}
if (sid == nullptr) {
android_errorWriteLog(0x534e4554, "121035042");
}
for (size_t i = 0; i < sizeof(user_perms) / sizeof(user_perms[0]); i++) {
struct user_perm user = user_perms[i];
if (user.uid == uid) {
return (user.perms & perm) && keystore_selinux_check_access(uid, perm, spid, sid);
}
}
return (DEFAULT_PERMS & perm) && keystore_selinux_check_access(uid, perm, spid, sid);
}
/**
* Returns true if the callingUid is allowed to interact in the targetUid's
* namespace.
*/
bool is_granted_to(uid_t callingUid, uid_t targetUid) {
if (callingUid == targetUid) {
return true;
}
for (size_t i = 0; i < sizeof(user_euids) / sizeof(user_euids[0]); i++) {
struct user_euid user = user_euids[i];
if (user.euid == callingUid && user.uid == targetUid) {
return true;
}
}
return false;
}
|
