efi_loader: display RO attribute with TEE-backed variables

A previous commit adds support for displaying variables RO flag.
Let's add it on the TEE backed variable storage as well.

Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

diff --git a/include/mm_communication.h b/include/mm_communication.h
index 193c4d1..f9c05bb 100644 (file)
--- a/include/mm_communication.h
+++ b/include/mm_communication.h
@@ -205,4 +205,47 @@ struct smm_variable_query_info {
        u32 attr;
 };
 
+#define VAR_CHECK_VARIABLE_PROPERTY_REVISION 0x0001
+#define VAR_CHECK_VARIABLE_PROPERTY_READ_ONLY BIT(0)
+/**
+ * struct var_check_property - Used to store variable properties in StMM
+ *
+ * @revision:   magic revision number for variable property checking
+ * @property:   properties mask for the variable used in StMM.
+ *              Currently RO flag is supported
+ * @attributes: variable attributes used in StMM checking when properties
+ *              for a variable are enabled
+ * @minsize:    minimum allowed size for variable payload checked against
+ *              smm_variable_access->datasize in StMM
+ * @maxsize:    maximum allowed size for variable payload checked against
+ *              smm_variable_access->datasize in StMM
+ *
+ * Defined in EDK2 as VAR_CHECK_VARIABLE_PROPERTY.
+ */
+struct var_check_property {
+       u16         revision;
+       u16         property;
+       u32         attributes;
+       efi_uintn_t minsize;
+       efi_uintn_t maxsize;
+};
+
+/**
+ * struct smm_variable_var_check_property - Used to communicate variable
+ *                                          properties with StMM
+ *
+ * @guid:       vendor GUID
+ * @name_size:  size of EFI name
+ * @property:   variable properties struct
+ * @name:       variable name
+ *
+ * Defined in EDK2 as SMM_VARIABLE_COMMUNICATE_VAR_CHECK_VARIABLE_PROPERTY.
+ */
+struct smm_variable_var_check_property {
+       efi_guid_t                guid;
+       efi_uintn_t               name_size;
+       struct var_check_property property;
+       u16                       name[];
+};
+
 #endif /* _MM_COMMUNICATION_H_ */

diff --git a/lib/efi_loader/efi_variable_tee.c b/lib/efi_loader/efi_variable_tee.c
index ff90aa8..24e0663 100644 (file)
--- a/lib/efi_loader/efi_variable_tee.c
+++ b/lib/efi_loader/efi_variable_tee.c
@@ -244,10 +244,92 @@ out:
        return ret;
 }
 
+/*
+ * StMM can store internal attributes and properties for variables, i.e enabling
+ * R/O variables
+ */
+static efi_status_t set_property_int(u16 *variable_name, efi_uintn_t name_size,
+                                    const efi_guid_t *vendor,
+                                    struct var_check_property *var_property)
+{
+       struct smm_variable_var_check_property *smm_property;
+       efi_uintn_t payload_size;
+       u8 *comm_buf = NULL;
+       efi_status_t ret;
+
+       payload_size = sizeof(*smm_property) + name_size;
+       if (payload_size > max_payload_size) {
+               ret = EFI_INVALID_PARAMETER;
+               goto out;
+       }
+       comm_buf = setup_mm_hdr((void **)&smm_property, payload_size,
+                               SMM_VARIABLE_FUNCTION_VAR_CHECK_VARIABLE_PROPERTY_SET,
+                               &ret);
+       if (!comm_buf)
+               goto out;
+
+       guidcpy(&smm_property->guid, vendor);
+       smm_property->name_size = name_size;
+       memcpy(&smm_property->property, var_property,
+              sizeof(smm_property->property));
+       memcpy(smm_property->name, variable_name, name_size);
+
+       ret = mm_communicate(comm_buf, payload_size);
+
+out:
+       free(comm_buf);
+       return ret;
+}
+
+static efi_status_t get_property_int(u16 *variable_name, efi_uintn_t name_size,
+                                    const efi_guid_t *vendor,
+                                    struct var_check_property *var_property)
+{
+       struct smm_variable_var_check_property *smm_property;
+       efi_uintn_t payload_size;
+       u8 *comm_buf = NULL;
+       efi_status_t ret;
+
+       memset(var_property, 0, sizeof(*var_property));
+       payload_size = sizeof(*smm_property) + name_size;
+       if (payload_size > max_payload_size) {
+               ret = EFI_INVALID_PARAMETER;
+               goto out;
+       }
+       comm_buf = setup_mm_hdr((void **)&smm_property, payload_size,
+                               SMM_VARIABLE_FUNCTION_VAR_CHECK_VARIABLE_PROPERTY_GET,
+                               &ret);
+       if (!comm_buf)
+               goto out;
+
+       guidcpy(&smm_property->guid, vendor);
+       smm_property->name_size = name_size;
+       memcpy(smm_property->name, variable_name, name_size);
+
+       ret = mm_communicate(comm_buf, payload_size);
+       /*
+        * Currently only R/O property is supported in StMM.
+        * Variables that are not set to R/O will not set the property in StMM
+        * and the call will return EFI_NOT_FOUND. We are setting the
+        * properties to 0x0 so checking against that is enough for the
+        * EFI_NOT_FOUND case.
+        */
+       if (ret == EFI_NOT_FOUND)
+               ret = EFI_SUCCESS;
+       if (ret != EFI_SUCCESS)
+               goto out;
+       memcpy(var_property, &smm_property->property, sizeof(*var_property));
+
+out:
+       free(comm_buf);
+       return ret;
+}
+
 efi_status_t efi_get_variable_int(u16 *variable_name, const efi_guid_t *vendor,
                                  u32 *attributes, efi_uintn_t *data_size,
                                  void *data, u64 *timep)
 {
+       struct var_check_property var_property;
        struct smm_variable_access *var_acc;
        efi_uintn_t payload_size;
        efi_uintn_t name_size;
@@ -299,8 +381,16 @@ efi_status_t efi_get_variable_int(u16 *variable_name, const efi_guid_t *vendor,
        if (ret != EFI_SUCCESS)
                goto out;
 
-       if (attributes)
+       ret = get_property_int(variable_name, name_size, vendor, &var_property);
+       if (ret != EFI_SUCCESS)
+               goto out;
+
+       if (attributes) {
                *attributes = var_acc->attr;
+               if (var_property.property & VAR_CHECK_VARIABLE_PROPERTY_READ_ONLY)
+                       *attributes |= EFI_VARIABLE_READ_ONLY;
+       }
+
        if (data)
                memcpy(data, (u8 *)var_acc->name + var_acc->name_size,
                       var_acc->data_size);
@@ -387,11 +477,13 @@ efi_status_t efi_set_variable_int(u16 *variable_name, const efi_guid_t *vendor,
                                  u32 attributes, efi_uintn_t data_size,
                                  const void *data, bool ro_check)
 {
+       efi_status_t ret, alt_ret = EFI_SUCCESS;
+       struct var_check_property var_property;
        struct smm_variable_access *var_acc;
        efi_uintn_t payload_size;
        efi_uintn_t name_size;
        u8 *comm_buf = NULL;
-       efi_status_t ret;
+       bool ro;
 
        if (!variable_name || variable_name[0] == 0 || !vendor) {
                ret = EFI_INVALID_PARAMETER;
@@ -401,7 +493,6 @@ efi_status_t efi_set_variable_int(u16 *variable_name, const efi_guid_t *vendor,
                ret = EFI_INVALID_PARAMETER;
                goto out;
        }
-
        /* Check payload size */
        name_size = u16_strsize(variable_name);
        payload_size = MM_VARIABLE_ACCESS_HEADER_SIZE + name_size + data_size;
@@ -410,12 +501,41 @@ efi_status_t efi_set_variable_int(u16 *variable_name, const efi_guid_t *vendor,
                goto out;
        }
 
-       /* Get communication buffer and initialize header */
+       /*
+        * Allocate the buffer early, before switching to RW (if needed)
+        * so we won't need to account for any failures in reading/setting
+        * the properties, if the allocation fails
+        */
        comm_buf = setup_mm_hdr((void **)&var_acc, payload_size,
                                SMM_VARIABLE_FUNCTION_SET_VARIABLE, &ret);
        if (!comm_buf)
                goto out;
 
+       ro = !!(attributes & EFI_VARIABLE_READ_ONLY);
+       attributes &= EFI_VARIABLE_MASK;
+
+       /*
+        * The API has the ability to override RO flags. If no RO check was
+        * requested switch the variable to RW for the duration of this call
+        */
+       ret = get_property_int(variable_name, name_size, vendor,
+                              &var_property);
+       if (ret != EFI_SUCCESS)
+               goto out;
+
+       if (var_property.property & VAR_CHECK_VARIABLE_PROPERTY_READ_ONLY) {
+               /* Bypass r/o check */
+               if (!ro_check) {
+                       var_property.property &= ~VAR_CHECK_VARIABLE_PROPERTY_READ_ONLY;
+                       ret = set_property_int(variable_name, name_size, vendor, &var_property);
+                       if (ret != EFI_SUCCESS)
+                               goto out;
+               } else {
+                       ret = EFI_WRITE_PROTECTED;
+                       goto out;
+               }
+       }
+
        /* Fill in contents */
        guidcpy(&var_acc->guid, vendor);
        var_acc->data_size = data_size;
@@ -426,10 +546,20 @@ efi_status_t efi_set_variable_int(u16 *variable_name, const efi_guid_t *vendor,
 
        /* Communicate */
        ret = mm_communicate(comm_buf, payload_size);
-
+       if (ret != EFI_SUCCESS)
+               alt_ret = ret;
+
+       if (ro && !(var_property.property & VAR_CHECK_VARIABLE_PROPERTY_READ_ONLY)) {
+               var_property.revision = VAR_CHECK_VARIABLE_PROPERTY_REVISION;
+               var_property.property |= VAR_CHECK_VARIABLE_PROPERTY_READ_ONLY;
+               var_property.attributes = attributes;
+               var_property.minsize = 1;
+               var_property.maxsize = var_acc->data_size;
+               ret = set_property_int(variable_name, name_size, vendor, &var_property);
+       }
 out:
        free(comm_buf);
-       return ret;
+       return alt_ret == EFI_SUCCESS ? ret : alt_ret;
 }
 
 efi_status_t efi_query_variable_info_int(u32 attributes,