From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nayna Jain Date: Sun, 25 Nov 2018 15:26:59 +0000 Subject: [PATCH 6/7] efi: Allow the "db" UEFI variable to be suppressed Message-Id: <20181125151500.8298-7-nayna@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit List-Id: References: <20181125151500.8298-1-nayna@linux.ibm.com> In-Reply-To: <20181125151500.8298-1-nayna@linux.ibm.com> To: linux-integrity@vger.kernel.org Cc: linux-security-module@vger.kernel.org, linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, zohar@linux.ibm.com, dhowells@redhat.com, jforbes@redhat.com, seth.forshee@canonical.com, kexec@lists.infradead.org, keyrings@vger.kernel.org, vgoyal@redhat.com, ebiederm@xmission.com, mpe@ellerman.id.au, Josh Boyer From: Josh Boyer 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. Signed-off-by: Josh Boyer Signed-off-by: David Howells Acked-by: Nayna Jain --- Changelog: v0: - No changes security/integrity/platform_certs/load_uefi.c | 44 +++++++++++++++++++++------ 1 file changed, 34 insertions(+), 10 deletions(-) diff --git a/security/integrity/platform_certs/load_uefi.c b/security/integrity/platform_certs/load_uefi.c index dbccb45147ef..978c8d0dc151 100644 --- a/security/integrity/platform_certs/load_uefi.c +++ b/security/integrity/platform_certs/load_uefi.c @@ -13,6 +13,26 @@ static __initdata efi_guid_t efi_cert_x509_sha256_guid = EFI_CERT_X509_SHA256_GU static __initdata efi_guid_t efi_cert_sha256_guid = 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. */ static __init void *get_cert_list(efi_char16_t *name, efi_guid_t *guid, @@ -113,7 +133,9 @@ static __init efi_element_handler_t get_handler_for_dbx(const efi_guid_t *sig_ty } /* - * Load the certs contained in the UEFI databases + * Load the certs contained in the UEFI databases into the secondary trusted + * keyring and the UEFI blacklisted X.509 cert SHA256 hashes into the blacklist + * keyring. */ static int __init load_uefi_certs(void) { @@ -129,15 +151,17 @@ 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); -- 2.13.6