efi_loader: image_loader: add a check against certificate type of authenticode

UEFI specification requires that we shall support three type of
certificates of authenticode in PE image:
  WIN_CERT_TYPE_EFI_GUID with the guid, EFI_CERT_TYPE_PCKS7_GUID
  WIN_CERT_TYPE_PKCS_SIGNED_DATA
  WIN_CERT_TYPE_EFI_PKCS1_15

As EDK2 does, we will support the first two that are pkcs7 SignedData.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>

diff --git a/lib/efi_loader/efi_image_loader.c b/lib/efi_loader/efi_image_loader.c
index 06a2ebd..9b01e1e 100644 (file)
--- a/lib/efi_loader/efi_image_loader.c
+++ b/lib/efi_loader/efi_image_loader.c
@@ -483,7 +483,8 @@ static bool efi_image_authenticate(void *efi, size_t efi_size)
        struct efi_signature_store *db = NULL, *dbx = NULL;
        struct x509_certificate *cert = NULL;
        void *new_efi = NULL;
-       size_t new_efi_size;
+       u8 *auth, *wincerts_end;
+       size_t new_efi_size, auth_size;
        bool ret = false;
 
        if (!efi_secure_boot_enabled())
@@ -532,21 +533,52 @@ static bool efi_image_authenticate(void *efi, size_t efi_size)
        }
 
        /* go through WIN_CERTIFICATE list */
-       for (wincert = wincerts;
-            (void *)wincert < (void *)wincerts + wincerts_len;
-            wincert = (void *)wincert + ALIGN(wincert->dwLength, 8)) {
-               if (wincert->dwLength < sizeof(*wincert)) {
-                       EFI_PRINT("%s: dwLength too small: %u < %zu\n",
-                                 __func__, wincert->dwLength,
-                                 sizeof(*wincert));
-                       goto err;
+       for (wincert = wincerts, wincerts_end = (u8 *)wincerts + wincerts_len;
+            (u8 *)wincert < wincerts_end;
+            wincert = (WIN_CERTIFICATE *)
+                       ((u8 *)wincert + ALIGN(wincert->dwLength, 8))) {
+               if ((u8 *)wincert + sizeof(*wincert) >= wincerts_end)
+                       break;
+
+               if (wincert->dwLength <= sizeof(*wincert)) {
+                       EFI_PRINT("dwLength too small: %u < %zu\n",
+                                 wincert->dwLength, sizeof(*wincert));
+                       continue;
+               }
+
+               EFI_PRINT("WIN_CERTIFICATE_TYPE: 0x%x\n",
+                         wincert->wCertificateType);
+
+               auth = (u8 *)wincert + sizeof(*wincert);
+               auth_size = wincert->dwLength - sizeof(*wincert);
+               if (wincert->wCertificateType == WIN_CERT_TYPE_EFI_GUID) {
+                       if (auth + sizeof(efi_guid_t) >= wincerts_end)
+                               break;
+
+                       if (auth_size <= sizeof(efi_guid_t)) {
+                               EFI_PRINT("dwLength too small: %u < %zu\n",
+                                         wincert->dwLength, sizeof(*wincert));
+                               continue;
+                       }
+                       if (guidcmp(auth, &efi_guid_cert_type_pkcs7)) {
+                               EFI_PRINT("Certificate type not supported: %pUl\n",
+                                         auth);
+                               continue;
+                       }
+
+                       auth += sizeof(efi_guid_t);
+                       auth_size -= sizeof(efi_guid_t);
+               } else if (wincert->wCertificateType
+                               != WIN_CERT_TYPE_PKCS_SIGNED_DATA) {
+                       EFI_PRINT("Certificate type not supported\n");
+                       continue;
                }
-               msg = pkcs7_parse_message((void *)wincert + sizeof(*wincert),
-                                         wincert->dwLength - sizeof(*wincert));
+
+               msg = pkcs7_parse_message(auth, auth_size);
                if (IS_ERR(msg)) {
                        EFI_PRINT("Parsing image's signature failed\n");
                        msg = NULL;
-                       goto err;
+                       continue;
                }
 
                /* try black-list first */