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authorJosh Boyer <jwboyer@fedoraproject.org>2018-12-09 01:57:04 +0530
committerMimi Zohar <zohar@linux.ibm.com>2018-12-12 22:09:10 -0500
commit386b49f51dc24d1f9139eb11f49aa075eeb35363 (patch)
treea9c07a6c594719a8faab034bbb4f8e9d129defb5 /security
parent15ea0e1e3e185040bed6119f815096f2e4326242 (diff)
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efi: Allow the "db" UEFI variable to be suppressed
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>
Diffstat (limited to 'security')
-rw-r--r--security/integrity/platform_certs/load_uefi.c45
1 files 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
@@ -16,6 +16,26 @@ static efi_guid_t efi_cert_x509_sha256_guid __initdata =
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.
*/
static __init void *get_cert_list(efi_char16_t *name, efi_guid_t *guid,
@@ -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);