From 2c3c1048746a4622d8c89a29670120dc8fab93c4 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 20:49:45 +0200 Subject: Adding upstream version 6.1.76. Signed-off-by: Daniel Baumann --- security/integrity/platform_certs/load_uefi.c | 238 ++++++++++++++++++++++++++ 1 file changed, 238 insertions(+) create mode 100644 security/integrity/platform_certs/load_uefi.c (limited to 'security/integrity/platform_certs/load_uefi.c') diff --git a/security/integrity/platform_certs/load_uefi.c b/security/integrity/platform_certs/load_uefi.c new file mode 100644 index 000000000..d1fdd1134 --- /dev/null +++ b/security/integrity/platform_certs/load_uefi.c @@ -0,0 +1,238 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include "../integrity.h" +#include "keyring_handler.h" + +/* + * On T2 Macs reading the db and dbx efi variables to load UEFI Secure Boot + * certificates causes occurrence of a page fault in Apple's firmware and + * a crash disabling EFI runtime services. The following quirk skips reading + * these variables. + */ +static const struct dmi_system_id uefi_skip_cert[] = { + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro15,1") }, + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro15,2") }, + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro15,3") }, + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro15,4") }, + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro16,1") }, + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro16,2") }, + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro16,3") }, + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro16,4") }, + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookAir8,1") }, + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookAir8,2") }, + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookAir9,1") }, + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "Macmini8,1") }, + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacPro7,1") }, + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "iMac20,1") }, + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "iMac20,2") }, + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "iMacPro1,1") }, + { } +}; + +/* + * Look to see if a UEFI variable called MokIgnoreDB exists and return true if + * it does. + * + * This UEFI variable is set by the shim if a user tells the shim to not use + * the certs/hashes in the UEFI db variable for verification purposes. If it + * is set, we should ignore the db variable also and the true return indicates + * this. + */ +static __init bool uefi_check_ignore_db(void) +{ + efi_status_t status; + unsigned int db = 0; + unsigned long size = sizeof(db); + efi_guid_t guid = EFI_SHIM_LOCK_GUID; + + status = efi.get_variable(L"MokIgnoreDB", &guid, NULL, &size, &db); + return status == EFI_SUCCESS; +} + +/* + * Get a certificate list blob from the named EFI variable. + */ +static __init void *get_cert_list(efi_char16_t *name, efi_guid_t *guid, + unsigned long *size, efi_status_t *status) +{ + unsigned long lsize = 4; + unsigned long tmpdb[4]; + void *db; + + *status = efi.get_variable(name, guid, NULL, &lsize, &tmpdb); + if (*status == EFI_NOT_FOUND) + return NULL; + + if (*status != EFI_BUFFER_TOO_SMALL) { + pr_err("Couldn't get size: 0x%lx\n", *status); + return NULL; + } + + db = kmalloc(lsize, GFP_KERNEL); + if (!db) + return NULL; + + *status = efi.get_variable(name, guid, NULL, &lsize, db); + if (*status != EFI_SUCCESS) { + kfree(db); + pr_err("Error reading db var: 0x%lx\n", *status); + return NULL; + } + + *size = lsize; + return db; +} + +/* + * load_moklist_certs() - Load MokList certs + * + * Load the certs contained in the UEFI MokListRT database into the + * platform trusted keyring. + * + * This routine checks the EFI MOK config table first. If and only if + * that fails, this routine uses the MokListRT ordinary UEFI variable. + * + * Return: Status + */ +static int __init load_moklist_certs(void) +{ + struct efi_mokvar_table_entry *mokvar_entry; + efi_guid_t mok_var = EFI_SHIM_LOCK_GUID; + void *mok; + unsigned long moksize; + efi_status_t status; + int rc; + + /* First try to load certs from the EFI MOKvar config table. + * It's not an error if the MOKvar config table doesn't exist + * or the MokListRT entry is not found in it. + */ + mokvar_entry = efi_mokvar_entry_find("MokListRT"); + if (mokvar_entry) { + rc = parse_efi_signature_list("UEFI:MokListRT (MOKvar table)", + mokvar_entry->data, + mokvar_entry->data_size, + get_handler_for_mok); + /* All done if that worked. */ + if (!rc) + return rc; + + pr_err("Couldn't parse MokListRT signatures from EFI MOKvar config table: %d\n", + rc); + } + + /* Get MokListRT. It might not exist, so it isn't an error + * if we can't get it. + */ + mok = get_cert_list(L"MokListRT", &mok_var, &moksize, &status); + if (mok) { + rc = parse_efi_signature_list("UEFI:MokListRT", + mok, moksize, get_handler_for_mok); + kfree(mok); + if (rc) + pr_err("Couldn't parse MokListRT signatures: %d\n", rc); + return rc; + } + if (status == EFI_NOT_FOUND) + pr_debug("MokListRT variable wasn't found\n"); + else + pr_info("Couldn't get UEFI MokListRT\n"); + return 0; +} + +/* + * load_uefi_certs() - Load certs from UEFI sources + * + * Load the certs contained in the UEFI databases into the platform trusted + * keyring and the UEFI blacklisted X.509 cert SHA256 hashes into the blacklist + * keyring. + */ +static int __init load_uefi_certs(void) +{ + efi_guid_t secure_var = EFI_IMAGE_SECURITY_DATABASE_GUID; + efi_guid_t mok_var = EFI_SHIM_LOCK_GUID; + void *db = NULL, *dbx = NULL, *mokx = NULL; + unsigned long dbsize = 0, dbxsize = 0, mokxsize = 0; + efi_status_t status; + int rc = 0; + const struct dmi_system_id *dmi_id; + + dmi_id = dmi_first_match(uefi_skip_cert); + if (dmi_id) { + pr_err("Reading UEFI Secure Boot Certs is not supported on T2 Macs.\n"); + return false; + } + + if (!efi_rt_services_supported(EFI_RT_SUPPORTED_GET_VARIABLE)) + return false; + + /* Get db and dbx. They might not exist, so it isn't an error + * if we can't get them. + */ + if (!uefi_check_ignore_db()) { + db = get_cert_list(L"db", &secure_var, &dbsize, &status); + if (!db) { + if (status == EFI_NOT_FOUND) + pr_debug("MODSIGN: db variable wasn't found\n"); + else + pr_err("MODSIGN: Couldn't get UEFI db list\n"); + } else { + rc = parse_efi_signature_list("UEFI:db", + db, dbsize, get_handler_for_db); + if (rc) + pr_err("Couldn't parse db signatures: %d\n", + rc); + kfree(db); + } + } + + dbx = get_cert_list(L"dbx", &secure_var, &dbxsize, &status); + if (!dbx) { + if (status == EFI_NOT_FOUND) + pr_debug("dbx variable wasn't found\n"); + else + pr_info("Couldn't get UEFI dbx list\n"); + } else { + rc = parse_efi_signature_list("UEFI:dbx", + dbx, dbxsize, + get_handler_for_dbx); + if (rc) + pr_err("Couldn't parse dbx signatures: %d\n", rc); + kfree(dbx); + } + + /* the MOK/MOKx can not be trusted when secure boot is disabled */ + if (!arch_ima_get_secureboot()) + return 0; + + mokx = get_cert_list(L"MokListXRT", &mok_var, &mokxsize, &status); + if (!mokx) { + if (status == EFI_NOT_FOUND) + pr_debug("mokx variable wasn't found\n"); + else + pr_info("Couldn't get mokx list\n"); + } else { + rc = parse_efi_signature_list("UEFI:MokListXRT", + mokx, mokxsize, + get_handler_for_dbx); + if (rc) + pr_err("Couldn't parse mokx signatures %d\n", rc); + kfree(mokx); + } + + /* Load the MokListRT certs */ + rc = load_moklist_certs(); + + return rc; +} +late_initcall(load_uefi_certs); -- cgit v1.2.3