From: Josh Boyer jwboyer@fedoraproject.org
If a user tells shim to not use the certs/hashes in the UEFI db variable for verification purposes, shim will set a UEFI variable called MokIgnoreDB. Have the uefi import code look for this and ignore the db variable if it is found.
[zohar@linux.ibm.com: removed reference to "secondary" keyring comment] Signed-off-by: Josh Boyer jwboyer@fedoraproject.org Signed-off-by: David Howells dhowells@redhat.com Acked-by: Nayna Jain nayna@linux.ibm.com Acked-by: Serge Hallyn serge@hallyn.com Reviewed-by: James Morris james.morris@microsoft.com Signed-off-by: Mimi Zohar zohar@linux.ibm.com Signed-off-by: Zhang Tianxing zhangtianxing3@huawei.com --- security/integrity/platform_certs/load_uefi.c | 45 ++++++++++++++----- 1 file changed, 35 insertions(+), 10 deletions(-)
diff --git a/security/integrity/platform_certs/load_uefi.c b/security/integrity/platform_certs/load_uefi.c index 8ceafa58d98c..81b19c52832b 100644 --- a/security/integrity/platform_certs/load_uefi.c +++ b/security/integrity/platform_certs/load_uefi.c @@ -15,6 +15,26 @@ static efi_guid_t efi_cert_x509_sha256_guid __initdata = EFI_CERT_X509_SHA256_GUID; static efi_guid_t efi_cert_sha256_guid __initdata = EFI_CERT_SHA256_GUID;
+/* + * 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. */ @@ -114,7 +134,9 @@ static __init efi_element_handler_t get_handler_for_dbx(const efi_guid_t * }
/* - * Load the certs contained in the UEFI databases + * 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) { @@ -130,15 +152,18 @@ static int __init load_uefi_certs(void) /* Get db, MokListRT, and dbx. They might not exist, so it isn't * an error if we can't get them. */ - db = get_cert_list(L"db", &secure_var, &dbsize); - if (!db) { - pr_err("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); + if (!uefi_check_ignore_db()) { + db = get_cert_list(L"db", &secure_var, &dbsize); + if (!db) { + 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); + } }
mok = get_cert_list(L"MokListRT", &mok_var, &moksize);