efi_loader: efi_tcg2_register returns appropriate error

This commit modify efi_tcg2_register() to return the
appropriate error.
With this fix, sandbox will not boot because efi_tcg2_register()
fails due to some missing feature in GetCapabilities.
So disable sandbox if EFI_TCG2_PROTOCOL is enabled.

UEFI secure boot variable measurement is not directly related
to TCG2 protocol installation, tcg2_measure_secure_boot_variable()
is moved to the separate function.

Signed-off-by: Masahisa Kojima <masahisa.kojima@linaro.org>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>

diff --git a/include/efi_loader.h b/include/efi_loader.h
index 67c40ca..f4860e8 100644 (file)
--- a/include/efi_loader.h
+++ b/include/efi_loader.h
@@ -525,6 +525,8 @@ efi_status_t efi_disk_register(void);
 efi_status_t efi_rng_register(void);
 /* Called by efi_init_obj_list() to install EFI_TCG2_PROTOCOL */
 efi_status_t efi_tcg2_register(void);
+/* Called by efi_init_obj_list() to do initial measurement */
+efi_status_t efi_tcg2_do_initial_measurement(void);
 /* measure the pe-coff image, extend PCR and add Event Log */
 efi_status_t tcg2_measure_pe_image(void *efi, u64 efi_size,
                                   struct efi_loaded_image_obj *handle,

diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig
index 700dc83..24f9a2b 100644 (file)
--- a/lib/efi_loader/Kconfig
+++ b/lib/efi_loader/Kconfig
@@ -308,6 +308,8 @@ config EFI_TCG2_PROTOCOL
        bool "EFI_TCG2_PROTOCOL support"
        default y
        depends on TPM_V2
+       # Sandbox TPM currently fails on GetCapabilities needed for TCG2
+       depends on !SANDBOX
        select SHA1
        select SHA256
        select SHA384

diff --git a/lib/efi_loader/efi_setup.c b/lib/efi_loader/efi_setup.c
index 1aba71c..49172e3 100644 (file)
--- a/lib/efi_loader/efi_setup.c
+++ b/lib/efi_loader/efi_setup.c
@@ -241,6 +241,10 @@ efi_status_t efi_init_obj_list(void)
                ret = efi_tcg2_register();
                if (ret != EFI_SUCCESS)
                        goto out;
+
+               ret = efi_tcg2_do_initial_measurement();
+               if (ret == EFI_SECURITY_VIOLATION)
+                       goto out;
        }
 
        /* Secure boot */

diff --git a/lib/efi_loader/efi_tcg2.c b/lib/efi_loader/efi_tcg2.c
index 5f71b18..bdfd9a3 100644 (file)
--- a/lib/efi_loader/efi_tcg2.c
+++ b/lib/efi_loader/efi_tcg2.c
@@ -153,6 +153,15 @@ static u16 alg_to_len(u16 hash_alg)
        return 0;
 }
 
+static bool is_tcg2_protocol_installed(void)
+{
+       struct efi_handler *handler;
+       efi_status_t ret;
+
+       ret = efi_search_protocol(efi_root, &efi_guid_tcg2_protocol, &handler);
+       return ret == EFI_SUCCESS;
+}
+
 static u32 tcg_event_final_size(struct tpml_digest_values *digest_list)
 {
        u32 len;
@@ -1664,6 +1673,14 @@ void tcg2_uninit(void)
        event_log.buffer = NULL;
        efi_free_pool(event_log.final_buffer);
        event_log.final_buffer = NULL;
+
+       if (!is_tcg2_protocol_installed())
+               return;
+
+       ret = efi_remove_protocol(efi_root, &efi_guid_tcg2_protocol,
+                                 (void *)&efi_tcg2_protocol);
+       if (ret != EFI_SUCCESS)
+               log_err("Failed to remove EFI TCG2 protocol\n");
 }
 
 /**
@@ -2346,11 +2363,36 @@ error:
 }
 
 /**
+ * efi_tcg2_do_initial_measurement() - do initial measurement
+ *
+ * Return:     status code
+ */
+efi_status_t efi_tcg2_do_initial_measurement(void)
+{
+       efi_status_t ret;
+       struct udevice *dev;
+
+       if (!is_tcg2_protocol_installed())
+               return EFI_SUCCESS;
+
+       ret = platform_get_tpm2_device(&dev);
+       if (ret != EFI_SUCCESS)
+               return EFI_SECURITY_VIOLATION;
+
+       ret = tcg2_measure_secure_boot_variable(dev);
+       if (ret != EFI_SUCCESS)
+               goto out;
+
+out:
+       return ret;
+}
+
+/**
  * efi_tcg2_register() - register EFI_TCG2_PROTOCOL
  *
  * If a TPM2 device is available, the TPM TCG2 Protocol is registered
  *
- * Return:     An error status is only returned if adding the protocol fails.
+ * Return:     status code
  */
 efi_status_t efi_tcg2_register(void)
 {
@@ -2373,8 +2415,10 @@ efi_status_t efi_tcg2_register(void)
        }
 
        ret = efi_init_event_log();
-       if (ret != EFI_SUCCESS)
+       if (ret != EFI_SUCCESS) {
+               tcg2_uninit();
                goto fail;
+       }
 
        ret = efi_add_protocol(efi_root, &efi_guid_tcg2_protocol,
                               (void *)&efi_tcg2_protocol);
@@ -2391,24 +2435,9 @@ efi_status_t efi_tcg2_register(void)
                goto fail;
        }
 
-       ret = tcg2_measure_secure_boot_variable(dev);
-       if (ret != EFI_SUCCESS) {
-               tcg2_uninit();
-               goto fail;
-       }
-
        return ret;
 
 fail:
        log_err("Cannot install EFI_TCG2_PROTOCOL\n");
-       /*
-        * Return EFI_SUCCESS and don't stop the EFI subsystem.
-        * That's done for 2 reasons
-        * - If the protocol is not installed the PCRs won't be extended.  So
-        *   someone later in the boot flow will notice that and take the
-        *   necessary actions.
-        * - The TPM sandbox is limited and we won't be able to run any efi
-        *   related tests with TCG2 enabled
-        */
-       return EFI_SUCCESS;
+       return ret;
 }