Shawn Willden | c1d1fee | 2016-01-26 22:44:56 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2016 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | #define LOG_TAG "keystore" |
| 18 | |
| 19 | #include "permissions.h" |
| 20 | |
Shawn Willden | c1d1fee | 2016-01-26 22:44:56 -0700 | [diff] [blame] | 21 | #include <cutils/sockets.h> |
Logan Chien | cdc813f | 2018-04-23 13:52:28 +0800 | [diff] [blame] | 22 | #include <log/log.h> |
Shawn Willden | c1d1fee | 2016-01-26 22:44:56 -0700 | [diff] [blame] | 23 | #include <private/android_filesystem_config.h> |
| 24 | |
| 25 | #include <selinux/android.h> |
| 26 | |
| 27 | #include "keystore_utils.h" |
| 28 | |
| 29 | /* perm_labels associcated with keystore_key SELinux class verbs. */ |
| 30 | const char* perm_labels[] = { |
Shawn Willden | e2a7b52 | 2017-04-11 09:27:40 -0600 | [diff] [blame] | 31 | "get_state", |
| 32 | "get", |
| 33 | "insert", |
| 34 | "delete", |
| 35 | "exist", |
| 36 | "list", |
| 37 | "reset", |
| 38 | "password", |
| 39 | "lock", |
| 40 | "unlock", |
| 41 | "is_empty", |
| 42 | "sign", |
| 43 | "verify", |
| 44 | "grant", |
| 45 | "duplicate", |
| 46 | "clear_uid", |
| 47 | "add_auth", |
| 48 | "user_changed", |
| 49 | "gen_unique_id", |
Shawn Willden | c1d1fee | 2016-01-26 22:44:56 -0700 | [diff] [blame] | 50 | }; |
| 51 | |
| 52 | struct user_euid { |
| 53 | uid_t uid; |
| 54 | uid_t euid; |
| 55 | }; |
| 56 | |
Branden Archer | 84e7231 | 2019-01-04 10:33:16 -0800 | [diff] [blame] | 57 | user_euid user_euids[] = {{AID_VPN, AID_SYSTEM}, |
| 58 | {AID_WIFI, AID_SYSTEM}, |
| 59 | {AID_ROOT, AID_SYSTEM}, |
| 60 | {AID_WIFI, AID_KEYSTORE}, |
| 61 | {AID_KEYSTORE, AID_WIFI}, |
Victor Hsieh | 58c10ac | 2019-09-05 14:25:54 -0700 | [diff] [blame] | 62 | {AID_FSVERITY_CERT, AID_ROOT}, |
| 63 | {AID_FSVERITY_CERT, AID_SYSTEM}, |
Branden Archer | 84e7231 | 2019-01-04 10:33:16 -0800 | [diff] [blame] | 64 | |
| 65 | #ifdef GRANT_ROOT_ALL_PERMISSIONS |
| 66 | // Allow VTS tests to act on behalf of the wifi user |
| 67 | {AID_WIFI, AID_ROOT} |
| 68 | #endif |
Shawn Willden | c1d1fee | 2016-01-26 22:44:56 -0700 | [diff] [blame] | 69 | }; |
| 70 | |
| 71 | struct user_perm { |
| 72 | uid_t uid; |
| 73 | perm_t perms; |
| 74 | }; |
| 75 | |
| 76 | static user_perm user_perms[] = { |
| 77 | {AID_SYSTEM, static_cast<perm_t>((uint32_t)(~0))}, |
| 78 | {AID_VPN, static_cast<perm_t>(P_GET | P_SIGN | P_VERIFY)}, |
| 79 | {AID_WIFI, static_cast<perm_t>(P_GET | P_SIGN | P_VERIFY)}, |
Branden Archer | a930c14 | 2019-02-21 14:42:30 -0800 | [diff] [blame] | 80 | {AID_BLUETOOTH, static_cast<perm_t>(P_GET | P_INSERT | P_DELETE | P_EXIST | P_SIGN | P_VERIFY)}, |
Branden Archer | 84e7231 | 2019-01-04 10:33:16 -0800 | [diff] [blame] | 81 | |
| 82 | #ifdef GRANT_ROOT_ALL_PERMISSIONS |
| 83 | // Allow VTS tests running as root to perform all operations |
| 84 | {AID_ROOT, static_cast<perm_t>((uint32_t)(~0))}, |
| 85 | #else |
Shawn Willden | c1d1fee | 2016-01-26 22:44:56 -0700 | [diff] [blame] | 86 | {AID_ROOT, static_cast<perm_t>(P_GET)}, |
Branden Archer | 84e7231 | 2019-01-04 10:33:16 -0800 | [diff] [blame] | 87 | #endif |
Shawn Willden | c1d1fee | 2016-01-26 22:44:56 -0700 | [diff] [blame] | 88 | }; |
| 89 | |
Shawn Willden | e2a7b52 | 2017-04-11 09:27:40 -0600 | [diff] [blame] | 90 | static const perm_t DEFAULT_PERMS = static_cast<perm_t>( |
| 91 | P_GET_STATE | P_GET | P_INSERT | P_DELETE | P_EXIST | P_LIST | P_SIGN | P_VERIFY | |
| 92 | P_GEN_UNIQUE_ID /* Only privileged apps can do this, but enforcement is done by SELinux */); |
Shawn Willden | c1d1fee | 2016-01-26 22:44:56 -0700 | [diff] [blame] | 93 | |
| 94 | struct audit_data { |
| 95 | pid_t pid; |
| 96 | uid_t uid; |
Steven Moreland | 23115b0 | 2019-01-10 16:20:20 -0800 | [diff] [blame] | 97 | const char* sid; |
Shawn Willden | c1d1fee | 2016-01-26 22:44:56 -0700 | [diff] [blame] | 98 | }; |
| 99 | |
| 100 | const char* get_perm_label(perm_t perm) { |
| 101 | unsigned int index = ffs(perm); |
| 102 | if (index > 0 && index <= (sizeof(perm_labels) / sizeof(perm_labels[0]))) { |
| 103 | return perm_labels[index - 1]; |
| 104 | } else { |
| 105 | ALOGE("Keystore: Failed to retrieve permission label.\n"); |
| 106 | abort(); |
| 107 | } |
| 108 | } |
| 109 | |
| 110 | static int audit_callback(void* data, security_class_t /* cls */, char* buf, size_t len) { |
| 111 | struct audit_data* ad = reinterpret_cast<struct audit_data*>(data); |
| 112 | if (!ad) { |
| 113 | ALOGE("No keystore audit data"); |
| 114 | return 0; |
| 115 | } |
| 116 | |
Steven Moreland | 23115b0 | 2019-01-10 16:20:20 -0800 | [diff] [blame] | 117 | const char* sid = ad->sid ? ad->sid : "N/A"; |
| 118 | snprintf(buf, len, "pid=%d uid=%d sid=%s", ad->pid, ad->uid, sid); |
Shawn Willden | c1d1fee | 2016-01-26 22:44:56 -0700 | [diff] [blame] | 119 | return 0; |
| 120 | } |
| 121 | |
| 122 | static char* tctx; |
Shawn Willden | c1d1fee | 2016-01-26 22:44:56 -0700 | [diff] [blame] | 123 | |
| 124 | int configure_selinux() { |
Nick Kralevich | d13eef0 | 2016-12-09 17:11:22 -0800 | [diff] [blame] | 125 | union selinux_callback cb; |
| 126 | cb.func_audit = audit_callback; |
| 127 | selinux_set_callback(SELINUX_CB_AUDIT, cb); |
| 128 | cb.func_log = selinux_log_callback; |
| 129 | selinux_set_callback(SELINUX_CB_LOG, cb); |
| 130 | if (getcon(&tctx) != 0) { |
| 131 | ALOGE("SELinux: Could not acquire target context. Aborting keystore.\n"); |
| 132 | return -1; |
Shawn Willden | c1d1fee | 2016-01-26 22:44:56 -0700 | [diff] [blame] | 133 | } |
| 134 | |
| 135 | return 0; |
| 136 | } |
| 137 | |
Steven Moreland | 23115b0 | 2019-01-10 16:20:20 -0800 | [diff] [blame] | 138 | static bool keystore_selinux_check_access(uid_t uid, perm_t perm, pid_t spid, const char* ssid) { |
Shawn Willden | c1d1fee | 2016-01-26 22:44:56 -0700 | [diff] [blame] | 139 | audit_data ad; |
Yi Kong | d291675 | 2018-07-26 17:44:27 -0700 | [diff] [blame] | 140 | char* sctx = nullptr; |
Shawn Willden | c1d1fee | 2016-01-26 22:44:56 -0700 | [diff] [blame] | 141 | const char* selinux_class = "keystore_key"; |
| 142 | const char* str_perm = get_perm_label(perm); |
| 143 | |
| 144 | if (!str_perm) { |
| 145 | return false; |
| 146 | } |
| 147 | |
Steven Moreland | 23115b0 | 2019-01-10 16:20:20 -0800 | [diff] [blame] | 148 | if (ssid == nullptr && getpidcon(spid, &sctx) != 0) { |
Shawn Willden | c1d1fee | 2016-01-26 22:44:56 -0700 | [diff] [blame] | 149 | ALOGE("SELinux: Failed to get source pid context.\n"); |
| 150 | return false; |
| 151 | } |
| 152 | |
Steven Moreland | 23115b0 | 2019-01-10 16:20:20 -0800 | [diff] [blame] | 153 | const char* use_sid = ssid ? ssid : sctx; |
| 154 | |
Shawn Willden | c1d1fee | 2016-01-26 22:44:56 -0700 | [diff] [blame] | 155 | ad.pid = spid; |
| 156 | ad.uid = uid; |
Steven Moreland | 23115b0 | 2019-01-10 16:20:20 -0800 | [diff] [blame] | 157 | ad.sid = use_sid; |
Shawn Willden | c1d1fee | 2016-01-26 22:44:56 -0700 | [diff] [blame] | 158 | |
Steven Moreland | 23115b0 | 2019-01-10 16:20:20 -0800 | [diff] [blame] | 159 | bool allowed = selinux_check_access(use_sid, tctx, selinux_class, str_perm, |
Shawn Willden | c1d1fee | 2016-01-26 22:44:56 -0700 | [diff] [blame] | 160 | reinterpret_cast<void*>(&ad)) == 0; |
| 161 | freecon(sctx); |
| 162 | return allowed; |
| 163 | } |
| 164 | |
| 165 | /** |
| 166 | * Returns the UID that the callingUid should act as. This is here for |
| 167 | * legacy support of the WiFi and VPN systems and should be removed |
| 168 | * when WiFi can operate in its own namespace. |
| 169 | */ |
| 170 | uid_t get_keystore_euid(uid_t uid) { |
| 171 | for (size_t i = 0; i < sizeof(user_euids) / sizeof(user_euids[0]); i++) { |
| 172 | struct user_euid user = user_euids[i]; |
| 173 | if (user.uid == uid) { |
| 174 | return user.euid; |
| 175 | } |
| 176 | } |
| 177 | |
| 178 | return uid; |
| 179 | } |
| 180 | |
Steven Moreland | 23115b0 | 2019-01-10 16:20:20 -0800 | [diff] [blame] | 181 | bool has_permission(uid_t uid, perm_t perm, pid_t spid, const char* sid) { |
Shawn Willden | c1d1fee | 2016-01-26 22:44:56 -0700 | [diff] [blame] | 182 | // All system users are equivalent for multi-user support. |
| 183 | if (get_app_id(uid) == AID_SYSTEM) { |
| 184 | uid = AID_SYSTEM; |
| 185 | } |
| 186 | |
Steven Moreland | 23115b0 | 2019-01-10 16:20:20 -0800 | [diff] [blame] | 187 | if (sid == nullptr) { |
| 188 | android_errorWriteLog(0x534e4554, "121035042"); |
| 189 | } |
| 190 | |
Shawn Willden | c1d1fee | 2016-01-26 22:44:56 -0700 | [diff] [blame] | 191 | for (size_t i = 0; i < sizeof(user_perms) / sizeof(user_perms[0]); i++) { |
| 192 | struct user_perm user = user_perms[i]; |
| 193 | if (user.uid == uid) { |
Steven Moreland | 23115b0 | 2019-01-10 16:20:20 -0800 | [diff] [blame] | 194 | return (user.perms & perm) && keystore_selinux_check_access(uid, perm, spid, sid); |
Shawn Willden | c1d1fee | 2016-01-26 22:44:56 -0700 | [diff] [blame] | 195 | } |
| 196 | } |
| 197 | |
Steven Moreland | 23115b0 | 2019-01-10 16:20:20 -0800 | [diff] [blame] | 198 | return (DEFAULT_PERMS & perm) && keystore_selinux_check_access(uid, perm, spid, sid); |
Shawn Willden | c1d1fee | 2016-01-26 22:44:56 -0700 | [diff] [blame] | 199 | } |
| 200 | |
| 201 | /** |
| 202 | * Returns true if the callingUid is allowed to interact in the targetUid's |
| 203 | * namespace. |
| 204 | */ |
| 205 | bool is_granted_to(uid_t callingUid, uid_t targetUid) { |
| 206 | if (callingUid == targetUid) { |
| 207 | return true; |
| 208 | } |
| 209 | for (size_t i = 0; i < sizeof(user_euids) / sizeof(user_euids[0]); i++) { |
| 210 | struct user_euid user = user_euids[i]; |
| 211 | if (user.euid == callingUid && user.uid == targetUid) { |
| 212 | return true; |
| 213 | } |
| 214 | } |
| 215 | |
| 216 | return false; |
| 217 | } |