| 1 | /* |
| 2 | * SPDX-License-Identifier: GPL-2.0-or-later |
| 3 | * |
| 4 | * uefi vars device - AuthVariableLib |
| 5 | */ |
| 6 | |
| 7 | #include "qemu/osdep.h" |
| 8 | #include "qemu/error-report.h" |
| 9 | #include "system/dma.h" |
| 10 | |
| 11 | #include "hw/uefi/var-service.h" |
| 12 | |
| 13 | static const uint16_t name_pk[] = u"PK"; |
| 14 | static const uint16_t name_kek[] = u"KEK"; |
| 15 | static const uint16_t name_db[] = u"db"; |
| 16 | static const uint16_t name_dbx[] = u"dbx"; |
| 17 | static const uint16_t name_setup_mode[] = u"SetupMode"; |
| 18 | static const uint16_t name_sigs_support[] = u"SignatureSupport"; |
| 19 | static const uint16_t name_sb[] = u"SecureBoot"; |
| 20 | static const uint16_t name_sb_enable[] = u"SecureBootEnable"; |
| 21 | static const uint16_t name_custom_mode[] = u"CustomMode"; |
| 22 | static const uint16_t name_vk[] = u"VendorKeys"; |
| 23 | static const uint16_t name_vk_nv[] = u"VendorKeysNv"; |
| 24 | |
| 25 | static const uint32_t sigdb_attrs = |
| 26 | EFI_VARIABLE_NON_VOLATILE | |
| 27 | EFI_VARIABLE_BOOTSERVICE_ACCESS | |
| 28 | EFI_VARIABLE_RUNTIME_ACCESS | |
| 29 | EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS; |
| 30 | |
| 31 | static void set_secure_boot(uefi_vars_state *uv, uint8_t sb) |
| 32 | { |
| 33 | uefi_vars_set_variable(uv, EfiGlobalVariable, |
| 34 | name_sb, sizeof(name_sb), |
| 35 | EFI_VARIABLE_BOOTSERVICE_ACCESS | |
| 36 | EFI_VARIABLE_RUNTIME_ACCESS, |
| 37 | &sb, sizeof(sb)); |
| 38 | } |
| 39 | |
| 40 | static void set_secure_boot_enable(uefi_vars_state *uv, uint8_t sbe) |
| 41 | { |
| 42 | uefi_vars_set_variable(uv, EfiSecureBootEnableDisable, |
| 43 | name_sb_enable, sizeof(name_sb_enable), |
| 44 | EFI_VARIABLE_NON_VOLATILE | |
| 45 | EFI_VARIABLE_BOOTSERVICE_ACCESS, |
| 46 | &sbe, sizeof(sbe)); |
| 47 | } |
| 48 | |
| 49 | static void set_setup_mode(uefi_vars_state *uv, uint8_t sm) |
| 50 | { |
| 51 | uefi_vars_set_variable(uv, EfiGlobalVariable, |
| 52 | name_setup_mode, sizeof(name_setup_mode), |
| 53 | EFI_VARIABLE_BOOTSERVICE_ACCESS | |
| 54 | EFI_VARIABLE_RUNTIME_ACCESS, |
| 55 | &sm, sizeof(sm)); |
| 56 | } |
| 57 | |
| 58 | static void set_custom_mode(uefi_vars_state *uv, uint8_t cm) |
| 59 | { |
| 60 | uefi_vars_set_variable(uv, EfiCustomModeEnable, |
| 61 | name_custom_mode, sizeof(name_custom_mode), |
| 62 | EFI_VARIABLE_NON_VOLATILE | |
| 63 | EFI_VARIABLE_BOOTSERVICE_ACCESS, |
| 64 | &cm, sizeof(cm)); |
| 65 | } |
| 66 | |
| 67 | static void set_signature_support(uefi_vars_state *uv) |
| 68 | { |
| 69 | QemuUUID sigs_support[5]; |
| 70 | |
| 71 | sigs_support[0] = EfiCertSha256Guid; |
| 72 | sigs_support[1] = EfiCertSha384Guid; |
| 73 | sigs_support[2] = EfiCertSha512Guid; |
| 74 | sigs_support[3] = EfiCertRsa2048Guid; |
| 75 | sigs_support[4] = EfiCertX509Guid; |
| 76 | |
| 77 | uefi_vars_set_variable(uv, EfiGlobalVariable, |
| 78 | name_sigs_support, sizeof(name_sigs_support), |
| 79 | EFI_VARIABLE_BOOTSERVICE_ACCESS | |
| 80 | EFI_VARIABLE_RUNTIME_ACCESS, |
| 81 | sigs_support, sizeof(sigs_support)); |
| 82 | } |
| 83 | |
| 84 | static bool setup_mode_is_active(uefi_vars_state *uv) |
| 85 | { |
| 86 | uefi_variable *var; |
| 87 | uint8_t *value; |
| 88 | |
| 89 | var = uefi_vars_find_variable(uv, EfiGlobalVariable, |
| 90 | name_setup_mode, sizeof(name_setup_mode)); |
| 91 | if (var) { |
| 92 | value = var->data; |
| 93 | if (value[0] == SETUP_MODE) { |
| 94 | return true; |
| 95 | } |
| 96 | } |
| 97 | return false; |
| 98 | } |
| 99 | |
| 100 | static bool custom_mode_is_active(uefi_vars_state *uv) |
| 101 | { |
| 102 | uefi_variable *var; |
| 103 | uint8_t *value; |
| 104 | |
| 105 | var = uefi_vars_find_variable(uv, EfiCustomModeEnable, |
| 106 | name_custom_mode, sizeof(name_custom_mode)); |
| 107 | if (var) { |
| 108 | value = var->data; |
| 109 | if (value[0] == CUSTOM_SECURE_BOOT_MODE) { |
| 110 | return true; |
| 111 | } |
| 112 | } |
| 113 | return false; |
| 114 | } |
| 115 | |
| 116 | bool uefi_vars_is_sb_pk(uefi_variable *var) |
| 117 | { |
| 118 | if (qemu_uuid_is_equal(&var->guid, &EfiGlobalVariable) && |
| 119 | uefi_str_equal(var->name, var->name_size, name_pk, sizeof(name_pk))) { |
| 120 | return true; |
| 121 | } |
| 122 | return false; |
| 123 | } |
| 124 | |
| 125 | static bool uefi_vars_is_sb_kek(uefi_variable *var) |
| 126 | { |
| 127 | if (qemu_uuid_is_equal(&var->guid, &EfiGlobalVariable) && |
| 128 | uefi_str_equal(var->name, var->name_size, name_kek, sizeof(name_kek))) { |
| 129 | return true; |
| 130 | } |
| 131 | return false; |
| 132 | } |
| 133 | |
| 134 | static bool uefi_vars_is_sb_db(uefi_variable *var) |
| 135 | { |
| 136 | if (!qemu_uuid_is_equal(&var->guid, &EfiImageSecurityDatabase)) { |
| 137 | return false; |
| 138 | } |
| 139 | if (uefi_str_equal(var->name, var->name_size, name_db, sizeof(name_db))) { |
| 140 | return true; |
| 141 | } |
| 142 | if (uefi_str_equal(var->name, var->name_size, name_dbx, sizeof(name_dbx))) { |
| 143 | return true; |
| 144 | } |
| 145 | return false; |
| 146 | } |
| 147 | |
| 148 | bool uefi_vars_is_sb_any(uefi_variable *var) |
| 149 | { |
| 150 | if (uefi_vars_is_sb_pk(var) || |
| 151 | uefi_vars_is_sb_kek(var) || |
| 152 | uefi_vars_is_sb_db(var)) { |
| 153 | return true; |
| 154 | } |
| 155 | return false; |
| 156 | } |
| 157 | |
| 158 | static uefi_variable *uefi_vars_find_siglist(uefi_vars_state *uv, |
| 159 | uefi_variable *var) |
| 160 | { |
| 161 | if (uefi_vars_is_sb_pk(var)) { |
| 162 | return uefi_vars_find_variable(uv, EfiGlobalVariable, |
| 163 | name_pk, sizeof(name_pk)); |
| 164 | } |
| 165 | if (uefi_vars_is_sb_kek(var)) { |
| 166 | return uefi_vars_find_variable(uv, EfiGlobalVariable, |
| 167 | name_pk, sizeof(name_pk)); |
| 168 | } |
| 169 | if (uefi_vars_is_sb_db(var)) { |
| 170 | return uefi_vars_find_variable(uv, EfiGlobalVariable, |
| 171 | name_kek, sizeof(name_kek)); |
| 172 | } |
| 173 | |
| 174 | return NULL; |
| 175 | } |
| 176 | |
| 177 | static efi_status uefi_vars_check_auth_2_sb(uefi_vars_state *uv, |
| 178 | uefi_variable *var, |
| 179 | mm_variable_access *va, |
| 180 | void *data, |
| 181 | uint64_t data_offset) |
| 182 | { |
| 183 | variable_auth_2 auth; |
| 184 | uefi_variable *siglist; |
| 185 | |
| 186 | memcpy(&auth, data, sizeof(auth)); |
| 187 | if (custom_mode_is_active(uv)) { |
| 188 | /* no authentication in custom mode */ |
| 189 | return EFI_SUCCESS; |
| 190 | } |
| 191 | |
| 192 | if (setup_mode_is_active(uv) && !uefi_vars_is_sb_pk(var)) { |
| 193 | /* no authentication in setup mode (except PK) */ |
| 194 | return EFI_SUCCESS; |
| 195 | } |
| 196 | |
| 197 | if (auth.hdr_length == (sizeof(auth) - sizeof(auth.timestamp))) { |
| 198 | /* no signature (auth->cert_data is empty) */ |
| 199 | return EFI_SECURITY_VIOLATION; |
| 200 | } |
| 201 | |
| 202 | siglist = uefi_vars_find_siglist(uv, var); |
| 203 | if (!siglist && setup_mode_is_active(uv) && uefi_vars_is_sb_pk(var)) { |
| 204 | /* check PK is self-signed */ |
| 205 | uefi_variable tmp = { |
| 206 | .guid = EfiGlobalVariable, |
| 207 | .name = (uint16_t *)name_pk, |
| 208 | .name_size = sizeof(name_pk), |
| 209 | .attributes = sigdb_attrs, |
| 210 | .data = data + data_offset, |
| 211 | .data_size = va->data_size - data_offset, |
| 212 | }; |
| 213 | return uefi_vars_check_pkcs7_2(&tmp, NULL, NULL, va, data); |
| 214 | } |
| 215 | |
| 216 | return uefi_vars_check_pkcs7_2(siglist, NULL, NULL, va, data); |
| 217 | } |
| 218 | |
| 219 | efi_status uefi_vars_check_auth_2(uefi_vars_state *uv, uefi_variable *var, |
| 220 | mm_variable_access *va, void *data) |
| 221 | { |
| 222 | variable_auth_2 auth; |
| 223 | uint64_t data_offset; |
| 224 | efi_status status; |
| 225 | |
| 226 | if (va->data_size < sizeof(auth)) { |
| 227 | return EFI_SECURITY_VIOLATION; |
| 228 | } |
| 229 | memcpy(&auth, data, sizeof(auth)); |
| 230 | |
| 231 | if (auth.hdr_length < (sizeof(auth) - sizeof(auth.timestamp))) { |
| 232 | return EFI_SECURITY_VIOLATION; |
| 233 | } |
| 234 | if (uadd64_overflow(sizeof(efi_time), auth.hdr_length, &data_offset)) { |
| 235 | return EFI_SECURITY_VIOLATION; |
| 236 | } |
| 237 | if (va->data_size < data_offset) { |
| 238 | return EFI_SECURITY_VIOLATION; |
| 239 | } |
| 240 | |
| 241 | if (auth.hdr_revision != 0x0200 || |
| 242 | auth.hdr_cert_type != WIN_CERT_TYPE_EFI_GUID || |
| 243 | !qemu_uuid_is_equal(&auth.guid_cert_type, &EfiCertTypePkcs7Guid)) { |
| 244 | return EFI_UNSUPPORTED; |
| 245 | } |
| 246 | |
| 247 | if (uefi_vars_is_sb_any(var)) { |
| 248 | /* secure boot variables */ |
| 249 | status = uefi_vars_check_auth_2_sb(uv, var, va, data, data_offset); |
| 250 | if (status != EFI_SUCCESS) { |
| 251 | return status; |
| 252 | } |
| 253 | } else { |
| 254 | /* other authenticated variables */ |
| 255 | status = uefi_vars_check_pkcs7_2(NULL, |
| 256 | &var->digest, &var->digest_size, |
| 257 | va, data); |
| 258 | if (status != EFI_SUCCESS) { |
| 259 | return status; |
| 260 | } |
| 261 | } |
| 262 | |
| 263 | /* checks passed, set variable data */ |
| 264 | var->time = auth.timestamp; |
| 265 | if (va->data_size - data_offset > 0) { |
| 266 | var->data = g_malloc(va->data_size - data_offset); |
| 267 | memcpy(var->data, data + data_offset, va->data_size - data_offset); |
| 268 | var->data_size = va->data_size - data_offset; |
| 269 | } |
| 270 | |
| 271 | return EFI_SUCCESS; |
| 272 | } |
| 273 | |
| 274 | efi_status uefi_vars_check_secure_boot(uefi_vars_state *uv, uefi_variable *var) |
| 275 | { |
| 276 | uint8_t *value = var->data; |
| 277 | |
| 278 | if (uefi_vars_is_sb_any(var)) { |
| 279 | if (var->attributes != sigdb_attrs) { |
| 280 | return EFI_INVALID_PARAMETER; |
| 281 | } |
| 282 | } |
| 283 | |
| 284 | /* reject SecureBootEnable updates if force_secure_boot is set */ |
| 285 | if (qemu_uuid_is_equal(&var->guid, &EfiSecureBootEnableDisable) && |
| 286 | uefi_str_equal(var->name, var->name_size, |
| 287 | name_sb_enable, sizeof(name_sb_enable)) && |
| 288 | uv->force_secure_boot && |
| 289 | value[0] != SECURE_BOOT_ENABLE) { |
| 290 | return EFI_WRITE_PROTECTED; |
| 291 | } |
| 292 | |
| 293 | /* reject CustomMode updates if disable_custom_mode is set */ |
| 294 | if (qemu_uuid_is_equal(&var->guid, &EfiCustomModeEnable) && |
| 295 | uefi_str_equal(var->name, var->name_size, |
| 296 | name_custom_mode, sizeof(name_custom_mode)) && |
| 297 | uv->disable_custom_mode) { |
| 298 | return EFI_WRITE_PROTECTED; |
| 299 | } |
| 300 | |
| 301 | /* reject SetupMode updates */ |
| 302 | if (qemu_uuid_is_equal(&var->guid, &EfiGlobalVariable) && |
| 303 | uefi_str_equal(var->name, var->name_size, |
| 304 | name_setup_mode, sizeof(name_setup_mode))) { |
| 305 | return EFI_WRITE_PROTECTED; |
| 306 | } |
| 307 | |
| 308 | return EFI_SUCCESS; |
| 309 | } |
| 310 | |
| 311 | /* AuthVariableLibInitialize */ |
| 312 | void uefi_vars_auth_init(uefi_vars_state *uv) |
| 313 | { |
| 314 | uefi_variable *pk_var, *sbe_var; |
| 315 | uint8_t platform_mode, sb, sbe, vk; |
| 316 | |
| 317 | /* SetupMode */ |
| 318 | pk_var = uefi_vars_find_variable(uv, EfiGlobalVariable, |
| 319 | name_pk, sizeof(name_pk)); |
| 320 | if (!pk_var) { |
| 321 | platform_mode = SETUP_MODE; |
| 322 | } else { |
| 323 | platform_mode = USER_MODE; |
| 324 | } |
| 325 | set_setup_mode(uv, platform_mode); |
| 326 | |
| 327 | /* SignatureSupport */ |
| 328 | set_signature_support(uv); |
| 329 | |
| 330 | /* SecureBootEnable */ |
| 331 | sbe = SECURE_BOOT_DISABLE; |
| 332 | sbe_var = uefi_vars_find_variable(uv, EfiSecureBootEnableDisable, |
| 333 | name_sb_enable, sizeof(name_sb_enable)); |
| 334 | if (sbe_var) { |
| 335 | if (platform_mode == USER_MODE) { |
| 336 | sbe = ((uint8_t *)sbe_var->data)[0]; |
| 337 | } |
| 338 | } else if (platform_mode == USER_MODE) { |
| 339 | sbe = SECURE_BOOT_ENABLE; |
| 340 | set_secure_boot_enable(uv, sbe); |
| 341 | } |
| 342 | |
| 343 | if (uv->force_secure_boot && sbe != SECURE_BOOT_ENABLE) { |
| 344 | sbe = SECURE_BOOT_ENABLE; |
| 345 | set_secure_boot_enable(uv, sbe); |
| 346 | } |
| 347 | |
| 348 | /* SecureBoot */ |
| 349 | if ((sbe == SECURE_BOOT_ENABLE) && (platform_mode == USER_MODE)) { |
| 350 | sb = SECURE_BOOT_MODE_ENABLE; |
| 351 | } else { |
| 352 | sb = SECURE_BOOT_MODE_DISABLE; |
| 353 | } |
| 354 | set_secure_boot(uv, sb); |
| 355 | |
| 356 | /* CustomMode */ |
| 357 | set_custom_mode(uv, STANDARD_SECURE_BOOT_MODE); |
| 358 | |
| 359 | vk = 0; |
| 360 | uefi_vars_set_variable(uv, EfiGlobalVariable, |
| 361 | name_vk_nv, sizeof(name_vk_nv), |
| 362 | EFI_VARIABLE_NON_VOLATILE | |
| 363 | EFI_VARIABLE_BOOTSERVICE_ACCESS | |
| 364 | EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS, |
| 365 | &vk, sizeof(vk)); |
| 366 | uefi_vars_set_variable(uv, EfiGlobalVariable, |
| 367 | name_vk, sizeof(name_vk), |
| 368 | EFI_VARIABLE_BOOTSERVICE_ACCESS | |
| 369 | EFI_VARIABLE_RUNTIME_ACCESS, |
| 370 | &vk, sizeof(vk)); |
| 371 | |
| 372 | /* flush to disk */ |
| 373 | uefi_vars_json_save(uv); |
| 374 | } |