diff options
Diffstat (limited to 'hw/uefi/var-service-auth.c')
| -rw-r--r-- | hw/uefi/var-service-auth.c | 361 |
1 files changed, 361 insertions, 0 deletions
diff --git a/hw/uefi/var-service-auth.c b/hw/uefi/var-service-auth.c new file mode 100644 index 0000000..fba5a09 --- /dev/null +++ b/hw/uefi/var-service-auth.c @@ -0,0 +1,361 @@ +/* + * SPDX-License-Identifier: GPL-2.0-or-later + * + * uefi vars device - AuthVariableLib + */ + +#include "qemu/osdep.h" +#include "qemu/error-report.h" +#include "system/dma.h" + +#include "hw/uefi/var-service.h" + +static const uint16_t name_pk[] = u"PK"; +static const uint16_t name_kek[] = u"KEK"; +static const uint16_t name_db[] = u"db"; +static const uint16_t name_dbx[] = u"dbx"; +static const uint16_t name_setup_mode[] = u"SetupMode"; +static const uint16_t name_sigs_support[] = u"SignatureSupport"; +static const uint16_t name_sb[] = u"SecureBoot"; +static const uint16_t name_sb_enable[] = u"SecureBootEnable"; +static const uint16_t name_custom_mode[] = u"CustomMode"; +static const uint16_t name_vk[] = u"VendorKeys"; +static const uint16_t name_vk_nv[] = u"VendorKeysNv"; + +static const uint32_t sigdb_attrs = + EFI_VARIABLE_NON_VOLATILE | + EFI_VARIABLE_BOOTSERVICE_ACCESS | + EFI_VARIABLE_RUNTIME_ACCESS | + EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS; + +static void set_secure_boot(uefi_vars_state *uv, uint8_t sb) +{ + uefi_vars_set_variable(uv, EfiGlobalVariable, + name_sb, sizeof(name_sb), + EFI_VARIABLE_BOOTSERVICE_ACCESS | + EFI_VARIABLE_RUNTIME_ACCESS, + &sb, sizeof(sb)); +} + +static void set_secure_boot_enable(uefi_vars_state *uv, uint8_t sbe) +{ + uefi_vars_set_variable(uv, EfiSecureBootEnableDisable, + name_sb_enable, sizeof(name_sb_enable), + EFI_VARIABLE_NON_VOLATILE | + EFI_VARIABLE_BOOTSERVICE_ACCESS, + &sbe, sizeof(sbe)); +} + +static void set_setup_mode(uefi_vars_state *uv, uint8_t sm) +{ + uefi_vars_set_variable(uv, EfiGlobalVariable, + name_setup_mode, sizeof(name_setup_mode), + EFI_VARIABLE_BOOTSERVICE_ACCESS | + EFI_VARIABLE_RUNTIME_ACCESS, + &sm, sizeof(sm)); +} + +static void set_custom_mode(uefi_vars_state *uv, uint8_t cm) +{ + uefi_vars_set_variable(uv, EfiCustomModeEnable, + name_custom_mode, sizeof(name_custom_mode), + EFI_VARIABLE_NON_VOLATILE | + EFI_VARIABLE_BOOTSERVICE_ACCESS, + &cm, sizeof(cm)); +} + +static void set_signature_support(uefi_vars_state *uv) +{ + QemuUUID sigs_support[5]; + + sigs_support[0] = EfiCertSha256Guid; + sigs_support[1] = EfiCertSha384Guid; + sigs_support[2] = EfiCertSha512Guid; + sigs_support[3] = EfiCertRsa2048Guid; + sigs_support[4] = EfiCertX509Guid; + + uefi_vars_set_variable(uv, EfiGlobalVariable, + name_sigs_support, sizeof(name_sigs_support), + EFI_VARIABLE_BOOTSERVICE_ACCESS | + EFI_VARIABLE_RUNTIME_ACCESS, + sigs_support, sizeof(sigs_support)); +} + +static bool setup_mode_is_active(uefi_vars_state *uv) +{ + uefi_variable *var; + uint8_t *value; + + var = uefi_vars_find_variable(uv, EfiGlobalVariable, + name_setup_mode, sizeof(name_setup_mode)); + if (var) { + value = var->data; + if (value[0] == SETUP_MODE) { + return true; + } + } + return false; +} + +static bool custom_mode_is_active(uefi_vars_state *uv) +{ + uefi_variable *var; + uint8_t *value; + + var = uefi_vars_find_variable(uv, EfiCustomModeEnable, + name_custom_mode, sizeof(name_custom_mode)); + if (var) { + value = var->data; + if (value[0] == CUSTOM_SECURE_BOOT_MODE) { + return true; + } + } + return false; +} + +bool uefi_vars_is_sb_pk(uefi_variable *var) +{ + if (qemu_uuid_is_equal(&var->guid, &EfiGlobalVariable) && + uefi_str_equal(var->name, var->name_size, name_pk, sizeof(name_pk))) { + return true; + } + return false; +} + +static bool uefi_vars_is_sb_kek(uefi_variable *var) +{ + if (qemu_uuid_is_equal(&var->guid, &EfiGlobalVariable) && + uefi_str_equal(var->name, var->name_size, name_kek, sizeof(name_kek))) { + return true; + } + return false; +} + +static bool uefi_vars_is_sb_db(uefi_variable *var) +{ + if (!qemu_uuid_is_equal(&var->guid, &EfiImageSecurityDatabase)) { + return false; + } + if (uefi_str_equal(var->name, var->name_size, name_db, sizeof(name_db))) { + return true; + } + if (uefi_str_equal(var->name, var->name_size, name_dbx, sizeof(name_dbx))) { + return true; + } + return false; +} + +bool uefi_vars_is_sb_any(uefi_variable *var) +{ + if (uefi_vars_is_sb_pk(var) || + uefi_vars_is_sb_kek(var) || + uefi_vars_is_sb_db(var)) { + return true; + } + return false; +} + +static uefi_variable *uefi_vars_find_siglist(uefi_vars_state *uv, + uefi_variable *var) +{ + if (uefi_vars_is_sb_pk(var)) { + return uefi_vars_find_variable(uv, EfiGlobalVariable, + name_pk, sizeof(name_pk)); + } + if (uefi_vars_is_sb_kek(var)) { + return uefi_vars_find_variable(uv, EfiGlobalVariable, + name_pk, sizeof(name_pk)); + } + if (uefi_vars_is_sb_db(var)) { + return uefi_vars_find_variable(uv, EfiGlobalVariable, + name_kek, sizeof(name_kek)); + } + + return NULL; +} + +static efi_status uefi_vars_check_auth_2_sb(uefi_vars_state *uv, + uefi_variable *var, + mm_variable_access *va, + void *data, + uint64_t data_offset) +{ + variable_auth_2 *auth = data; + uefi_variable *siglist; + + if (custom_mode_is_active(uv)) { + /* no authentication in custom mode */ + return EFI_SUCCESS; + } + + if (setup_mode_is_active(uv) && !uefi_vars_is_sb_pk(var)) { + /* no authentication in setup mode (except PK) */ + return EFI_SUCCESS; + } + + if (auth->hdr_length == 24) { + /* no signature (auth->cert_data is empty) */ + return EFI_SECURITY_VIOLATION; + } + + siglist = uefi_vars_find_siglist(uv, var); + if (!siglist && setup_mode_is_active(uv) && uefi_vars_is_sb_pk(var)) { + /* check PK is self-signed */ + uefi_variable tmp = { + .guid = EfiGlobalVariable, + .name = (uint16_t *)name_pk, + .name_size = sizeof(name_pk), + .attributes = sigdb_attrs, + .data = data + data_offset, + .data_size = va->data_size - data_offset, + }; + return uefi_vars_check_pkcs7_2(&tmp, NULL, NULL, va, data); + } + + return uefi_vars_check_pkcs7_2(siglist, NULL, NULL, va, data); +} + +efi_status uefi_vars_check_auth_2(uefi_vars_state *uv, uefi_variable *var, + mm_variable_access *va, void *data) +{ + variable_auth_2 *auth = data; + uint64_t data_offset; + efi_status status; + + if (va->data_size < sizeof(*auth)) { + return EFI_SECURITY_VIOLATION; + } + if (uadd64_overflow(sizeof(efi_time), auth->hdr_length, &data_offset)) { + return EFI_SECURITY_VIOLATION; + } + if (va->data_size < data_offset) { + return EFI_SECURITY_VIOLATION; + } + + if (auth->hdr_revision != 0x0200 || + auth->hdr_cert_type != WIN_CERT_TYPE_EFI_GUID || + !qemu_uuid_is_equal(&auth->guid_cert_type, &EfiCertTypePkcs7Guid)) { + return EFI_UNSUPPORTED; + } + + if (uefi_vars_is_sb_any(var)) { + /* secure boot variables */ + status = uefi_vars_check_auth_2_sb(uv, var, va, data, data_offset); + if (status != EFI_SUCCESS) { + return status; + } + } else { + /* other authenticated variables */ + status = uefi_vars_check_pkcs7_2(NULL, + &var->digest, &var->digest_size, + va, data); + if (status != EFI_SUCCESS) { + return status; + } + } + + /* checks passed, set variable data */ + var->time = auth->timestamp; + if (va->data_size - data_offset > 0) { + var->data = g_malloc(va->data_size - data_offset); + memcpy(var->data, data + data_offset, va->data_size - data_offset); + var->data_size = va->data_size - data_offset; + } + + return EFI_SUCCESS; +} + +efi_status uefi_vars_check_secure_boot(uefi_vars_state *uv, uefi_variable *var) +{ + uint8_t *value = var->data; + + if (uefi_vars_is_sb_any(var)) { + if (var->attributes != sigdb_attrs) { + return EFI_INVALID_PARAMETER; + } + } + + /* reject SecureBootEnable updates if force_secure_boot is set */ + if (qemu_uuid_is_equal(&var->guid, &EfiSecureBootEnableDisable) && + uefi_str_equal(var->name, var->name_size, + name_sb_enable, sizeof(name_sb_enable)) && + uv->force_secure_boot && + value[0] != SECURE_BOOT_ENABLE) { + return EFI_WRITE_PROTECTED; + } + + /* reject CustomMode updates if disable_custom_mode is set */ + if (qemu_uuid_is_equal(&var->guid, &EfiCustomModeEnable) && + uefi_str_equal(var->name, var->name_size, + name_custom_mode, sizeof(name_custom_mode)) && + uv->disable_custom_mode) { + return EFI_WRITE_PROTECTED; + } + + return EFI_SUCCESS; +} + +/* AuthVariableLibInitialize */ +void uefi_vars_auth_init(uefi_vars_state *uv) +{ + uefi_variable *pk_var, *sbe_var; + uint8_t platform_mode, sb, sbe, vk; + + /* SetupMode */ + pk_var = uefi_vars_find_variable(uv, EfiGlobalVariable, + name_pk, sizeof(name_pk)); + if (!pk_var) { + platform_mode = SETUP_MODE; + } else { + platform_mode = USER_MODE; + } + set_setup_mode(uv, platform_mode); + + /* SignatureSupport */ + set_signature_support(uv); + + /* SecureBootEnable */ + sbe = SECURE_BOOT_DISABLE; + sbe_var = uefi_vars_find_variable(uv, EfiSecureBootEnableDisable, + name_sb_enable, sizeof(name_sb_enable)); + if (sbe_var) { + if (platform_mode == USER_MODE) { + sbe = ((uint8_t *)sbe_var->data)[0]; + } + } else if (platform_mode == USER_MODE) { + sbe = SECURE_BOOT_ENABLE; + set_secure_boot_enable(uv, sbe); + } + + if (uv->force_secure_boot && sbe != SECURE_BOOT_ENABLE) { + sbe = SECURE_BOOT_ENABLE; + set_secure_boot_enable(uv, sbe); + } + + /* SecureBoot */ + if ((sbe == SECURE_BOOT_ENABLE) && (platform_mode == USER_MODE)) { + sb = SECURE_BOOT_MODE_ENABLE; + } else { + sb = SECURE_BOOT_MODE_DISABLE; + } + set_secure_boot(uv, sb); + + /* CustomMode */ + set_custom_mode(uv, STANDARD_SECURE_BOOT_MODE); + + vk = 0; + uefi_vars_set_variable(uv, EfiGlobalVariable, + name_vk_nv, sizeof(name_vk_nv), + EFI_VARIABLE_NON_VOLATILE | + EFI_VARIABLE_BOOTSERVICE_ACCESS | + EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS, + &vk, sizeof(vk)); + uefi_vars_set_variable(uv, EfiGlobalVariable, + name_vk, sizeof(name_vk), + EFI_VARIABLE_BOOTSERVICE_ACCESS | + EFI_VARIABLE_RUNTIME_ACCESS, + &vk, sizeof(vk)); + + /* flush to disk */ + uefi_vars_json_save(uv); +} |