Merge changes from topic "tbbr/fw_enc" into integration

* changes:
  docs: qemu: Add instructions to boot using FIP image
  docs: Update docs with firmware encryption feature
  qemu: Support optional encryption of BL31 and BL32 images
  qemu: Update flash address map to keep FIP in secure FLASH0
  Makefile: Add support to optionally encrypt BL31 and BL32
  tools: Add firmware authenticated encryption tool
  TBB: Add an IO abstraction layer to load encrypted firmwares
  drivers: crypto: Add authenticated decryption framework

Makefile

@@ -159,6 +159,14 @@ else
 endif
 endif
 
+ifneq (${DECRYPTION_SUPPORT},none)
+ENC_ARGS += -f ${FW_ENC_STATUS}
+ENC_ARGS += -k ${ENC_KEY}
+ENC_ARGS += -n ${ENC_NONCE}
+FIP_DEPS += enctool
+FWU_FIP_DEPS += enctool
+endif
+
 ################################################################################
 # Toolchain
 ################################################################################
@@ -623,7 +631,7 @@ endif
 
 ifeq ($(MEASURED_BOOT),1)
     ifneq (${TRUSTED_BOARD_BOOT},1)
-        $(error MEASURED_BOOT requires TRUSTED_BOARD_BOOT=1")
+        $(error MEASURED_BOOT requires TRUSTED_BOARD_BOOT=1)
     else
         $(info MEASURED_BOOT is an experimental feature)
     endif
@@ -635,6 +643,14 @@ ifeq (${ARM_XLAT_TABLES_LIB_V1}, 1)
     endif
 endif
 
+ifneq (${DECRYPTION_SUPPORT},none)
+    ifeq (${TRUSTED_BOARD_BOOT}, 0)
+        $(error TRUSTED_BOARD_BOOT must be enabled for DECRYPTION_SUPPORT to be set)
+    else
+        $(info DECRYPTION_SUPPORT is an experimental feature)
+    endif
+endif
+
 ################################################################################
 # Process platform overrideable behaviour
 ################################################################################
@@ -708,6 +724,10 @@ include lib/stack_protector/stack_protector.mk
 CRTTOOLPATH		?=	tools/cert_create
 CRTTOOL			?=	${CRTTOOLPATH}/cert_create${BIN_EXT}
 
+# Variables for use with Firmware Encryption Tool
+ENCTOOLPATH		?=	tools/encrypt_fw
+ENCTOOL			?=	${ENCTOOLPATH}/encrypt_fw${BIN_EXT}
+
 # Variables for use with Firmware Image Package
 FIPTOOLPATH		?=	tools/fiptool
 FIPTOOL			?=	${FIPTOOLPATH}/fiptool${BIN_EXT}
@@ -814,10 +834,13 @@ $(eval $(call assert_boolean,BL2_AT_EL3))
 $(eval $(call assert_boolean,BL2_IN_XIP_MEM))
 $(eval $(call assert_boolean,BL2_INV_DCACHE))
 $(eval $(call assert_boolean,USE_SPINLOCK_CAS))
+$(eval $(call assert_boolean,ENCRYPT_BL31))
+$(eval $(call assert_boolean,ENCRYPT_BL32))
 
 $(eval $(call assert_numeric,ARM_ARCH_MAJOR))
 $(eval $(call assert_numeric,ARM_ARCH_MINOR))
 $(eval $(call assert_numeric,BRANCH_PROTECTION))
+$(eval $(call assert_numeric,FW_ENC_STATUS))
 
 ifdef KEY_SIZE
         $(eval $(call assert_numeric,KEY_SIZE))
@@ -843,6 +866,7 @@ $(eval $(call add_define,CTX_INCLUDE_PAUTH_REGS))
 $(eval $(call add_define,EL3_EXCEPTION_HANDLING))
 $(eval $(call add_define,CTX_INCLUDE_MTE_REGS))
 $(eval $(call add_define,CTX_INCLUDE_EL2_REGS))
+$(eval $(call add_define,DECRYPTION_SUPPORT_${DECRYPTION_SUPPORT}))
 $(eval $(call add_define,ENABLE_AMU))
 $(eval $(call add_define,ENABLE_ASSERTIONS))
 $(eval $(call add_define,ENABLE_BTI))
@@ -854,6 +878,8 @@ $(eval $(call add_define,ENABLE_PSCI_STAT))
 $(eval $(call add_define,ENABLE_RUNTIME_INSTRUMENTATION))
 $(eval $(call add_define,ENABLE_SPE_FOR_LOWER_ELS))
 $(eval $(call add_define,ENABLE_SVE_FOR_NS))
+$(eval $(call add_define,ENCRYPT_BL31))
+$(eval $(call add_define,ENCRYPT_BL32))
 $(eval $(call add_define,ERROR_DEPRECATED))
 $(eval $(call add_define,FAULT_INJECTION_SUPPORT))
 $(eval $(call add_define,GICV2_G0_FOR_EL3))
@@ -926,7 +952,7 @@ endif
 # Build targets
 ################################################################################
 
-.PHONY:	all msg_start clean realclean distclean cscope locate-checkpatch checkcodebase checkpatch fiptool sptool fip sp fwu_fip certtool dtbs memmap doc
+.PHONY:	all msg_start clean realclean distclean cscope locate-checkpatch checkcodebase checkpatch fiptool sptool fip sp fwu_fip certtool dtbs memmap doc enctool
 .SUFFIXES:
 
 all: msg_start
@@ -974,9 +1000,14 @@ endif
 
 ifeq (${NEED_BL31},yes)
 BL31_SOURCES += ${SPD_SOURCES}
+ifneq (${DECRYPTION_SUPPORT},none)
+$(if ${BL31}, $(eval $(call TOOL_ADD_IMG,bl31,--soc-fw,,$(ENCRYPT_BL31))),\
+	$(eval $(call MAKE_BL,31,soc-fw,,$(ENCRYPT_BL31))))
+else
 $(if ${BL31}, $(eval $(call TOOL_ADD_IMG,bl31,--soc-fw)),\
 	$(eval $(call MAKE_BL,31,soc-fw)))
 endif
+endif
 
 # If a BL32 image is needed but neither BL32 nor BL32_SOURCES is defined, the
 # build system will call TOOL_ADD_IMG to print a warning message and abort the
@@ -985,9 +1016,14 @@ ifeq (${NEED_BL32},yes)
 
 BUILD_BL32 := $(if $(BL32),,$(if $(BL32_SOURCES),1))
 
+ifneq (${DECRYPTION_SUPPORT},none)
+$(if ${BUILD_BL32}, $(eval $(call MAKE_BL,32,tos-fw,,$(ENCRYPT_BL32))),\
+	$(eval $(call TOOL_ADD_IMG,bl32,--tos-fw,,$(ENCRYPT_BL32))))
+else
 $(if ${BUILD_BL32}, $(eval $(call MAKE_BL,32,tos-fw)),\
 	$(eval $(call TOOL_ADD_IMG,bl32,--tos-fw)))
 endif
+endif
 
 # Add the BL33 image if required by the platform
 ifeq (${NEED_BL33},yes)
@@ -1029,6 +1065,7 @@ clean:
 	$(call SHELL_REMOVE_DIR,${BUILD_PLAT})
 	${Q}${MAKE} --no-print-directory -C ${FIPTOOLPATH} clean
 	${Q}${MAKE} PLAT=${PLAT} --no-print-directory -C ${CRTTOOLPATH} clean
+	${Q}${MAKE} PLAT=${PLAT} --no-print-directory -C ${ENCTOOLPATH} clean
 	${Q}${MAKE} --no-print-directory -C ${ROMLIBPATH} clean
 
 realclean distclean:
@@ -1038,6 +1075,7 @@ realclean distclean:
 	${Q}${MAKE} --no-print-directory -C ${FIPTOOLPATH} clean
 	${Q}${MAKE} --no-print-directory -C ${SPTOOLPATH} clean
 	${Q}${MAKE} PLAT=${PLAT} --no-print-directory -C ${CRTTOOLPATH} clean
+	${Q}${MAKE} PLAT=${PLAT} --no-print-directory -C ${ENCTOOLPATH} realclean
 	${Q}${MAKE} --no-print-directory -C ${ROMLIBPATH} clean
 
 checkcodebase:		locate-checkpatch
@@ -1139,6 +1177,15 @@ doc:
 	@echo "  BUILD DOCUMENTATION"
 	${Q}${MAKE} --no-print-directory -C ${DOCS_PATH} html
 
+enctool: ${ENCTOOL}
+
+.PHONY: ${ENCTOOL}
+${ENCTOOL}:
+	${Q}${MAKE} PLAT=${PLAT} BUILD_INFO=0 --no-print-directory -C ${ENCTOOLPATH}
+	@${ECHO_BLANK_LINE}
+	@echo "Built $@ successfully"
+	@${ECHO_BLANK_LINE}
+
 cscope:
 	@echo "  CSCOPE"
 	${Q}find ${CURDIR} -name "*.[chsS]" > cscope.files
@@ -1175,6 +1222,7 @@ help:
 	@echo "  cscope         Generate cscope index"
 	@echo "  distclean      Remove all build artifacts for all platforms"
 	@echo "  certtool       Build the Certificate generation tool"
+	@echo "  enctool        Build the Firmware encryption tool"
 	@echo "  fiptool        Build the Firmware Image Package (FIP) creation tool"
 	@echo "  sp             Build the Secure Partition Packages"
 	@echo "  sptool         Build the Secure Partition Package creation tool"

docs/change-log-upcoming.rst

@@ -46,6 +46,7 @@ New Features
 
 - Security
    - Example: "UBSAN support and handlers"
+   - Add support for optional firmware encryption feature (experimental).
 
 - Tools
    - Example: "fiptool: Add support to build fiptool on Windows."

docs/design/auth-framework.rst

@@ -934,7 +934,7 @@ i.e. verify a hash or a digital signature. Arm platforms will use a library
 based on mbed TLS, which can be found in
 ``drivers/auth/mbedtls/mbedtls_crypto.c``. This library is registered in the
 authentication framework using the macro ``REGISTER_CRYPTO_LIB()`` and exports
-three functions:
+four functions:
 
 .. code:: c
 
@@ -945,6 +945,11 @@ three functions:
                          void *pk_ptr, unsigned int pk_len);
     int verify_hash(void *data_ptr, unsigned int data_len,
                     void *digest_info_ptr, unsigned int digest_info_len);
+    int auth_decrypt(enum crypto_dec_algo dec_algo, void *data_ptr,
+                     size_t len, const void *key, unsigned int key_len,
+                     unsigned int key_flags, const void *iv,
+                     unsigned int iv_len, const void *tag,
+                     unsigned int tag_len)
 
 The mbedTLS library algorithm support is configured by both the
 ``TF_MBEDTLS_KEY_ALG`` and ``TF_MBEDTLS_KEY_SIZE`` variables.
@@ -957,6 +962,9 @@ The mbedTLS library algorithm support is configured by both the
 -  ``TF_MBEDTLS_KEY_SIZE`` sets the supported RSA key size for TFA. Valid values
    include 1024, 2048, 3072 and 4096.
 
+-  ``TF_MBEDTLS_USE_AES_GCM`` enables the authenticated decryption support based
+   on AES-GCM algorithm. Valid values are 0 and 1.
+
 .. note::
    If code size is a concern, the build option ``MBEDTLS_SHA256_SMALLER`` can
    be defined in the platform Makefile. It will make mbed TLS use an

docs/design/trusted-board-boot.rst

@@ -229,6 +229,34 @@ library that is required is given in the :ref:`Prerequisites` document.
 Instructions for building and using the tool can be found at
 :ref:`tools_build_cert_create`.
 
+Authenticated Encryption Framework
+----------------------------------
+
+The authenticated encryption framework included in TF-A provides support to
+implement the optional firmware encryption feature. This feature can be
+optionally enabled on platforms to implement the optional requirement:
+R060_TBBR_FUNCTION as specified in the `Trusted Board Boot Requirements (TBBR)`_
+document.
+
+Note that due to security considerations and complexity of this feature, it is
+marked as experimental.
+
+Firmware Encryption Tool
+------------------------
+
+The ``encrypt_fw`` tool is built and runs on the host machine as part of the
+TF-A build process when ``DECRYPTION_SUPPORT != none``. It takes the plain
+firmware image as input and generates the encrypted firmware image which can
+then be passed as input to the ``fiptool`` utility for creating the FIP.
+
+The encrypted firmwares are also stored individually in the output build
+directory.
+
+The tool resides in the ``tools/encrypt_fw`` directory. It uses OpenSSL SSL
+library version 1.0.1 or later to do authenticated encryption operation.
+Instructions for building and using the tool can be found in the
+:ref:`tools_build_enctool`.
+
 --------------
 
 *Copyright (c) 2015-2019, Arm Limited and Contributors. All rights reserved.*

docs/getting_started/build-options.rst

@@ -160,6 +160,12 @@ Common build options
 -  ``DEBUG``: Chooses between a debug and release build. It can take either 0
    (release) or 1 (debug) as values. 0 is the default.
 
+-  ``DECRYPTION_SUPPORT``: This build flag enables the user to select the
+   authenticated decryption algorithm to be used to decrypt firmware/s during
+   boot. It accepts 2 values: ``aes_gcm`` and ``none``. The default value of
+   this flag is ``none`` to disable firmware decryption which is an optional
+   feature as per TBBR. Also, it is an experimental feature.
+
 -  ``DISABLE_BIN_GENERATION``: Boolean option to disable the generation
    of the binary image. If set to 1, then only the ELF image is built.
    0 is the default.
@@ -257,6 +263,22 @@ Common build options
    platform hook needs to be implemented. The value is passed as the last
    component of the option ``-fstack-protector-$ENABLE_STACK_PROTECTOR``.
 
+-  ``ENCRYPT_BL31``: Binary flag to enable encryption of BL31 firmware. This
+   flag depends on ``DECRYPTION_SUPPORT`` build flag which is marked as
+   experimental.
+
+-  ``ENCRYPT_BL32``: Binary flag to enable encryption of Secure BL32 payload.
+   This flag depends on ``DECRYPTION_SUPPORT`` build flag which is marked as
+   experimental.
+
+-  ``ENC_KEY``: A 32-byte (256-bit) symmetric key in hex string format. It could
+   either be SSK or BSSK depending on ``FW_ENC_STATUS`` flag. This value depends
+   on ``DECRYPTION_SUPPORT`` build flag which is marked as experimental.
+
+-  ``ENC_NONCE``: A 12-byte (96-bit) encryption nonce or Initialization Vector
+   (IV) in hex string format. This value depends on ``DECRYPTION_SUPPORT``
+   build flag which is marked as experimental.
+
 -  ``ERROR_DEPRECATED``: This option decides whether to treat the usage of
    deprecated platform APIs, helper functions or drivers within Trusted
    Firmware as error. It can take the value 1 (flag the use of deprecated
@@ -281,6 +303,18 @@ Common build options
 -  ``FWU_FIP_NAME``: This is an optional build option which specifies the FWU
    FIP filename for the ``fwu_fip`` target. Default is ``fwu_fip.bin``.
 
+-  ``FW_ENC_STATUS``: Top level firmware's encryption numeric flag, values:
+
+   ::
+
+     0: Encryption is done with Secret Symmetric Key (SSK) which is common
+        for a class of devices.
+     1: Encryption is done with Binding Secret Symmetric Key (BSSK) which is
+        unique per device.
+
+   This flag depends on ``DECRYPTION_SUPPORT`` build flag which is marked as
+   experimental.
+
 -  ``GENERATE_COT``: Boolean flag used to build and execute the ``cert_create``
    tool to create certificates as per the Chain of Trust described in
    :ref:`Trusted Board Boot`. The build system then calls ``fiptool`` to

docs/getting_started/porting-guide.rst

@@ -872,6 +872,35 @@ twice.
 
 On success the function should return 0 and a negative error code otherwise.
 
+Function : plat_get_enc_key_info() [when FW_ENC_STATUS == 0 or 1]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+    Arguments : enum fw_enc_status_t fw_enc_status, uint8_t *key,
+                size_t *key_len, unsigned int *flags, const uint8_t *img_id,
+                size_t img_id_len
+    Return    : int
+
+This function provides a symmetric key (either SSK or BSSK depending on
+fw_enc_status) which is invoked during runtime decryption of encrypted
+firmware images. `plat/common/plat_bl_common.c` provides a dummy weak
+implementation for testing purposes which must be overridden by the platform
+trying to implement a real world firmware encryption use-case.
+
+It also allows the platform to pass symmetric key identifier rather than
+actual symmetric key which is useful in cases where the crypto backend provides
+secure storage for the symmetric key. So in this case ``ENC_KEY_IS_IDENTIFIER``
+flag must be set in ``flags``.
+
+In addition to above a platform may also choose to provide an image specific
+symmetric key/identifier using img_id.
+
+On success the function should return 0 and a negative error code otherwise.
+
+Note that this API depends on ``DECRYPTION_SUPPORT`` build flag which is
+marked as experimental.
+
 Common optional modifications
 -----------------------------
 

docs/getting_started/tools-build.rst

@@ -135,6 +135,33 @@ verbose. The following command should be used to obtain help about the tool:
 
     ./tools/cert_create/cert_create -h
 
+.. _tools_build_enctool:
+
+Building the Firmware Encryption Tool
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The ``encrypt_fw`` tool is built as part of the TF-A build process when the
+``fip`` make target is specified, DECRYPTION_SUPPORT and TBB are enabled, but
+it can also be built separately with the following command:
+
+.. code:: shell
+
+    make PLAT=<platform> [DEBUG=1] [V=1] enctool
+
+``DEBUG=1`` builds the tool in debug mode. ``V=1`` makes the build process more
+verbose. The following command should be used to obtain help about the tool:
+
+.. code:: shell
+
+    ./tools/encrypt_fw/encrypt_fw -h
+
+Note that the enctool in its current implementation only supports encryption
+key to be provided in plain format. A typical implementation can very well
+extend this tool to support custom techniques to protect encryption key.
+
+Also, a user may choose to provide encryption key or nonce as an input file
+via using ``cat <filename>`` instead of a hex string.
+
 --------------
 
 *Copyright (c) 2019, Arm Limited. All rights reserved.*

docs/plat/qemu.rst

@@ -21,11 +21,13 @@ Current limitations:
 
 -  Only cold boot is supported
 -  No build instructions for QEMU\_EFI.fd and rootfs-arm64.cpio.gz
--  No instructions for how to load a BL32 (Secure Payload)
 
 ``QEMU_EFI.fd`` can be dowloaded from
 http://snapshots.linaro.org/components/kernel/leg-virt-tianocore-edk2-upstream/latest/QEMU-KERNEL-AARCH64/RELEASE_GCC5/QEMU_EFI.fd
 
+Booting via semi-hosting option
+-------------------------------
+
 Boot binaries, except BL1, are primarily loaded via semi-hosting so all
 binaries has to reside in the same directory as QEMU is started from. This
 is conveniently achieved with symlinks the local names as:
@@ -50,3 +52,52 @@ To start (QEMU v4.1.0):
         -append "console=ttyAMA0,38400 keep_bootcon root=/dev/vda2"   \
         -initrd rootfs-arm64.cpio.gz -smp 2 -m 1024 -bios bl1.bin   \
         -d unimp -semihosting-config enable,target=native
+
+Booting via flash based firmwares
+---------------------------------
+
+Boot firmwares are loaded via secure FLASH0 device so ``bl1.bin`` and
+``fip.bin`` should be concatenated to create a ``flash.bin`` that is flashed
+onto secure FLASH0.
+
+-  ``bl32.bin`` -> BL32 (``tee-header_v2.bin``)
+-  ``bl32_extra1.bin`` -> BL32 Extra1 (``tee-pager_v2.bin``)
+-  ``bl32_extra2.bin`` -> BL32 Extra2 (``tee-pageable_v2.bin``)
+-  ``bl33.bin`` -> BL33 (``QEMU_EFI.fd``)
+-  ``Image`` -> linux/arch/arm64/boot/Image
+
+To build:
+
+.. code:: shell
+
+    make CROSS_COMPILE=aarch64-linux-gnu- PLAT=qemu BL32=bl32.bin \
+        BL32_EXTRA1=bl32_extra1.bin BL32_EXTRA2=bl32_extra2.bin \
+        BL33=bl33.bin BL32_RAM_LOCATION=tdram SPD=opteed all fip
+
+To build with TBBR enabled, BL31 and BL32 encrypted with test key:
+
+.. code:: shell
+
+    make CROSS_COMPILE=aarch64-linux-gnu- PLAT=qemu BL32=bl32.bin \
+        BL32_EXTRA1=bl32_extra1.bin BL32_EXTRA2=bl32_extra2.bin \
+        BL33=bl33.bin BL32_RAM_LOCATION=tdram SPD=opteed all fip \
+        MBEDTLS_DIR=<path-to-mbedtls-repo> TRUSTED_BOARD_BOOT=1 \
+        GENERATE_COT=1 DECRYPTION_SUPPORT=aes_gcm FW_ENC_STATUS=0 \
+        ENCRYPT_BL31=1 ENCRYPT_BL32=1
+
+To build flash.bin:
+
+.. code:: shell
+
+    dd if=build/qemu/release/bl1.bin of=flash.bin bs=4096 conv=notrunc
+    dd if=build/qemu/release/fip.bin of=flash.bin seek=64 bs=4096 conv=notrunc
+
+To start (QEMU v2.6.0):
+
+.. code:: shell
+
+    qemu-system-aarch64 -nographic -machine virt,secure=on -cpu cortex-a57  \
+        -kernel Image -no-acpi                     \
+        -append 'console=ttyAMA0,38400 keep_bootcon root=/dev/vda2'  \
+        -initrd rootfs-arm64.cpio.gz -smp 2 -m 1024 -bios flash.bin   \
+        -d unimp

drivers/auth/crypto_mod.c

@@ -124,3 +124,35 @@ int crypto_mod_calc_hash(unsigned int alg, void *data_ptr,
 	return crypto_lib_desc.calc_hash(alg, data_ptr, data_len, output);
 }
 #endif	/* MEASURED_BOOT */
+
+/*
+ * Authenticated decryption of data
+ *
+ * Parameters:
+ *
+ *   dec_algo: authenticated decryption algorithm
+ *   data_ptr, len: data to be decrypted (inout param)
+ *   key, key_len, key_flags: symmetric decryption key
+ *   iv, iv_len: initialization vector
+ *   tag, tag_len: authentication tag
+ */
+int crypto_mod_auth_decrypt(enum crypto_dec_algo dec_algo, void *data_ptr,
+			    size_t len, const void *key, unsigned int key_len,
+			    unsigned int key_flags, const void *iv,
+			    unsigned int iv_len, const void *tag,
+			    unsigned int tag_len)
+{
+	assert(crypto_lib_desc.auth_decrypt != NULL);
+	assert(data_ptr != NULL);
+	assert(len != 0U);
+	assert(key != NULL);
+	assert(key_len != 0U);
+	assert(iv != NULL);
+	assert((iv_len != 0U) && (iv_len <= CRYPTO_MAX_IV_SIZE));
+	assert(tag != NULL);
+	assert((tag_len != 0U) && (tag_len <= CRYPTO_MAX_TAG_SIZE));
+
+	return crypto_lib_desc.auth_decrypt(dec_algo, data_ptr, len, key,
+					    key_len, key_flags, iv, iv_len, tag,
+					    tag_len);
+}

drivers/auth/cryptocell/712/cryptocell_crypto.c

@@ -301,5 +301,5 @@ static int verify_hash(void *data_ptr, unsigned int data_len,
 /*
  * Register crypto library descriptor
  */
-REGISTER_CRYPTO_LIB(LIB_NAME, init, verify_signature, verify_hash);
+REGISTER_CRYPTO_LIB(LIB_NAME, init, verify_signature, verify_hash, NULL);
 

drivers/auth/mbedtls/mbedtls_common.mk

@@ -23,13 +23,17 @@ MBEDTLS_SOURCES	+=		drivers/auth/mbedtls/mbedtls_common.c
 
 
 LIBMBEDTLS_SRCS		:= $(addprefix ${MBEDTLS_DIR}/library/,	\
+					aes.c 					\
 					asn1parse.c 				\
 					asn1write.c 				\
+					cipher.c 				\
+					cipher_wrap.c 				\
 					memory_buffer_alloc.c			\
 					oid.c 					\
 					platform.c 				\
 					platform_util.c				\
 					bignum.c				\
+					gcm.c 					\
 					md.c					\
 					md_wrap.c				\
 					pk.c 					\
@@ -87,11 +91,17 @@ else
     $(error "TF_MBEDTLS_KEY_ALG=${TF_MBEDTLS_KEY_ALG} not supported on mbed TLS")
 endif
 
+ifeq (${DECRYPTION_SUPPORT}, aes_gcm)
+    TF_MBEDTLS_USE_AES_GCM	:=	1
+else
+    TF_MBEDTLS_USE_AES_GCM	:=	0
+endif
+
 # Needs to be set to drive mbed TLS configuration correctly
 $(eval $(call add_define,TF_MBEDTLS_KEY_ALG_ID))
 $(eval $(call add_define,TF_MBEDTLS_KEY_SIZE))
 $(eval $(call add_define,TF_MBEDTLS_HASH_ALG_ID))
-
+$(eval $(call add_define,TF_MBEDTLS_USE_AES_GCM))
 
 $(eval $(call MAKE_LIB,mbedtls))
 

drivers/auth/mbedtls/mbedtls_crypto.c

@@ -4,10 +4,12 @@
  * SPDX-License-Identifier: BSD-3-Clause
  */
 
+#include <assert.h>
 #include <stddef.h>
 #include <string.h>
 
 /* mbed TLS headers */
+#include <mbedtls/gcm.h>
 #include <mbedtls/md.h>
 #include <mbedtls/memory_buffer_alloc.h>
 #include <mbedtls/oid.h>
@@ -17,6 +19,7 @@
 #include <drivers/auth/crypto_mod.h>
 #include <drivers/auth/mbedtls/mbedtls_common.h>
 #include <drivers/auth/mbedtls/mbedtls_config.h>
+#include <plat/common/platform.h>
 
 #define LIB_NAME		"mbed TLS"
 
@@ -226,11 +229,121 @@ int calc_hash(unsigned int alg, void *data_ptr,
 }
 #endif /* MEASURED_BOOT */
 
+#if TF_MBEDTLS_USE_AES_GCM
+/*
+ * Stack based buffer allocation for decryption operation. It could
+ * be configured to balance stack usage vs execution speed.
+ */
+#define DEC_OP_BUF_SIZE		128
+
+static int aes_gcm_decrypt(void *data_ptr, size_t len, const void *key,
+			   unsigned int key_len, const void *iv,
+			   unsigned int iv_len, const void *tag,
+			   unsigned int tag_len)
+{
+	mbedtls_gcm_context ctx;
+	mbedtls_cipher_id_t cipher = MBEDTLS_CIPHER_ID_AES;
+	unsigned char buf[DEC_OP_BUF_SIZE];
+	unsigned char tag_buf[CRYPTO_MAX_TAG_SIZE];
+	unsigned char *pt = data_ptr;
+	size_t dec_len;
+	int diff, i, rc;
+
+	mbedtls_gcm_init(&ctx);
+
+	rc = mbedtls_gcm_setkey(&ctx, cipher, key, key_len * 8);
+	if (rc != 0) {
+		rc = CRYPTO_ERR_DECRYPTION;
+		goto exit_gcm;
+	}
+
+	rc = mbedtls_gcm_starts(&ctx, MBEDTLS_GCM_DECRYPT, iv, iv_len, NULL, 0);
+	if (rc != 0) {
+		rc = CRYPTO_ERR_DECRYPTION;
+		goto exit_gcm;
+	}
+
+	while (len > 0) {
+		dec_len = MIN(sizeof(buf), len);
+
+		rc = mbedtls_gcm_update(&ctx, dec_len, pt, buf);
+		if (rc != 0) {
+			rc = CRYPTO_ERR_DECRYPTION;
+			goto exit_gcm;
+		}
+
+		memcpy(pt, buf, dec_len);
+		pt += dec_len;
+		len -= dec_len;
+	}
+
+	rc = mbedtls_gcm_finish(&ctx, tag_buf, sizeof(tag_buf));
+	if (rc != 0) {
+		rc = CRYPTO_ERR_DECRYPTION;
+		goto exit_gcm;
+	}
+
+	/* Check tag in "constant-time" */
+	for (diff = 0, i = 0; i < tag_len; i++)
+		diff |= ((const unsigned char *)tag)[i] ^ tag_buf[i];
+
+	if (diff != 0) {
+		rc = CRYPTO_ERR_DECRYPTION;
+		goto exit_gcm;
+	}
+
+	/* GCM decryption success */
+	rc = CRYPTO_SUCCESS;
+
+exit_gcm:
+	mbedtls_gcm_free(&ctx);
+	return rc;
+}
+
+/*
+ * Authenticated decryption of an image
+ */
+static int auth_decrypt(enum crypto_dec_algo dec_algo, void *data_ptr,
+			size_t len, const void *key, unsigned int key_len,
+			unsigned int key_flags, const void *iv,
+			unsigned int iv_len, const void *tag,
+			unsigned int tag_len)
+{
+	int rc;
+
+	assert((key_flags & ENC_KEY_IS_IDENTIFIER) == 0);
+
+	switch (dec_algo) {
+	case CRYPTO_GCM_DECRYPT:
+		rc = aes_gcm_decrypt(data_ptr, len, key, key_len, iv, iv_len,
+				     tag, tag_len);
+		if (rc != 0)
+			return rc;
+		break;
+	default:
+		return CRYPTO_ERR_DECRYPTION;
+	}
+
+	return CRYPTO_SUCCESS;
+}
+#endif /* TF_MBEDTLS_USE_AES_GCM */
+
 /*
  * Register crypto library descriptor
  */
 #if MEASURED_BOOT
-REGISTER_CRYPTO_LIB(LIB_NAME, init, verify_signature, verify_hash, calc_hash);
+#if TF_MBEDTLS_USE_AES_GCM
+REGISTER_CRYPTO_LIB(LIB_NAME, init, verify_signature, verify_hash, calc_hash,
+		    auth_decrypt);
+#else
+REGISTER_CRYPTO_LIB(LIB_NAME, init, verify_signature, verify_hash, calc_hash,
+		    NULL);
+#endif
+#else /* MEASURED_BOOT */
+#if TF_MBEDTLS_USE_AES_GCM
+REGISTER_CRYPTO_LIB(LIB_NAME, init, verify_signature, verify_hash,
+		    auth_decrypt);
 #else
-REGISTER_CRYPTO_LIB(LIB_NAME, init, verify_signature, verify_hash);
+REGISTER_CRYPTO_LIB(LIB_NAME, init, verify_signature, verify_hash, NULL);
+#endif
 #endif /* MEASURED_BOOT */

drivers/io/io_encrypted.c

+/*
+ * Copyright (c) 2020, Linaro Limited. All rights reserved.
+ * Author: Sumit Garg <sumit.garg@linaro.org>
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <assert.h>
+#include <errno.h>
+#include <stdint.h>
+#include <string.h>
+
+#include <platform_def.h>
+
+#include <common/bl_common.h>
+#include <common/debug.h>
+#include <drivers/auth/crypto_mod.h>
+#include <drivers/io/io_driver.h>
+#include <drivers/io/io_encrypted.h>
+#include <drivers/io/io_storage.h>
+#include <lib/utils.h>
+#include <plat/common/platform.h>
+#include <tools_share/firmware_encrypted.h>
+#include <tools_share/uuid.h>
+
+static uintptr_t backend_dev_handle;
+static uintptr_t backend_dev_spec;
+static uintptr_t backend_handle;
+static uintptr_t backend_image_spec;
+
+static io_dev_info_t enc_dev_info;
+
+/* Encrypted firmware driver functions */
+static int enc_dev_open(const uintptr_t dev_spec, io_dev_info_t **dev_info);
+static int enc_file_open(io_dev_info_t *dev_info, const uintptr_t spec,
+			  io_entity_t *entity);
+static int enc_file_len(io_entity_t *entity, size_t *length);
+static int enc_file_read(io_entity_t *entity, uintptr_t buffer, size_t length,
+			  size_t *length_read);
+static int enc_file_close(io_entity_t *entity);
+static int enc_dev_init(io_dev_info_t *dev_info, const uintptr_t init_params);
+static int enc_dev_close(io_dev_info_t *dev_info);
+
+static inline int is_valid_header(struct fw_enc_hdr *header)
+{
+	if (header->magic == ENC_HEADER_MAGIC)
+		return 1;
+	else
+		return 0;
+}
+
+static io_type_t device_type_enc(void)
+{
+	return IO_TYPE_ENCRYPTED;
+}
+
+static const io_dev_connector_t enc_dev_connector = {
+	.dev_open = enc_dev_open
+};
+
+static const io_dev_funcs_t enc_dev_funcs = {
+	.type = device_type_enc,
+	.open = enc_file_open,
+	.seek = NULL,
+	.size = enc_file_len,
+	.read = enc_file_read,
+	.write = NULL,
+	.close = enc_file_close,
+	.dev_init = enc_dev_init,
+	.dev_close = enc_dev_close,
+};
+
+static int enc_dev_open(const uintptr_t dev_spec, io_dev_info_t **dev_info)
+{
+	assert(dev_info != NULL);
+
+	enc_dev_info.funcs = &enc_dev_funcs;
+	*dev_info = &enc_dev_info;
+
+	return 0;
+}
+
+static int enc_dev_init(io_dev_info_t *dev_info, const uintptr_t init_params)
+{
+	int result;
+	unsigned int image_id = (unsigned int)init_params;
+
+	/* Obtain a reference to the image by querying the platform layer */
+	result = plat_get_image_source(image_id, &backend_dev_handle,
+				       &backend_dev_spec);
+	if (result != 0) {
+		WARN("Failed to obtain reference to image id=%u (%i)\n",
+			image_id, result);
+		return -ENOENT;
+	}
+
+	return result;
+}
+
+static int enc_dev_close(io_dev_info_t *dev_info)
+{
+	backend_dev_handle = (uintptr_t)NULL;
+	backend_dev_spec = (uintptr_t)NULL;
+
+	return 0;
+}
+
+static int enc_file_open(io_dev_info_t *dev_info, const uintptr_t spec,
+			 io_entity_t *entity)
+{
+	int result;
+
+	assert(spec != 0);
+	assert(entity != NULL);
+
+	backend_image_spec = spec;
+
+	result = io_open(backend_dev_handle, backend_image_spec,
+			 &backend_handle);
+	if (result != 0) {
+		WARN("Failed to open backend device (%i)\n", result);
+		result = -ENOENT;
+	}
+
+	return result;
+}
+
+static int enc_file_len(io_entity_t *entity, size_t *length)
+{
+	int result;
+
+	assert(entity != NULL);
+	assert(length != NULL);
+
+	result = io_size(backend_handle, length);
+	if (result != 0) {
+		WARN("Failed to read blob length (%i)\n", result);
+		return -ENOENT;
+	}
+
+	/*
+	 * Encryption header is attached at the beginning of the encrypted file
+	 * and is not considered a part of the payload.
+	 */
+	if (*length < sizeof(struct fw_enc_hdr))
+		return -EIO;
+
+	*length -= sizeof(struct fw_enc_hdr);
+
+	return result;
+}
+
+static int enc_file_read(io_entity_t *entity, uintptr_t buffer, size_t length,
+			 size_t *length_read)
+{
+	int result;
+	struct fw_enc_hdr header;
+	enum fw_enc_status_t fw_enc_status;
+	size_t bytes_read;
+	uint8_t key[ENC_MAX_KEY_SIZE];
+	size_t key_len = sizeof(key);
+	unsigned int key_flags = 0;
+	const io_uuid_spec_t *uuid_spec = (io_uuid_spec_t *)backend_image_spec;
+
+	assert(entity != NULL);
+	assert(length_read != NULL);
+
+	result = io_read(backend_handle, (uintptr_t)&header, sizeof(header),
+			 &bytes_read);
+	if (result != 0) {
+		WARN("Failed to read encryption header (%i)\n", result);
+		return -ENOENT;
+	}
+
+	if (!is_valid_header(&header)) {
+		WARN("Encryption header check failed.\n");
+		return -ENOENT;
+	}
+
+	VERBOSE("Encryption header looks OK.\n");
+	fw_enc_status = header.flags & FW_ENC_STATUS_FLAG_MASK;
+
+	if ((header.iv_len > ENC_MAX_IV_SIZE) ||
+	    (header.tag_len > ENC_MAX_TAG_SIZE)) {
+		WARN("Incorrect IV or tag length\n");
+		return -ENOENT;
+	}
+
+	result = io_read(backend_handle, buffer, length, &bytes_read);
+	if (result != 0) {
+		WARN("Failed to read encrypted payload (%i)\n", result);
+		return -ENOENT;
+	}
+
+	*length_read = bytes_read;
+
+	result = plat_get_enc_key_info(fw_enc_status, key, &key_len, &key_flags,
+				       (uint8_t *)&uuid_spec->uuid,
+				       sizeof(uuid_t));
+	if (result != 0) {
+		WARN("Failed to obtain encryption key (%i)\n", result);
+		return -ENOENT;
+	}
+
+	result = crypto_mod_auth_decrypt(header.dec_algo,
+					 (void *)buffer, *length_read, key,
+					 key_len, key_flags, header.iv,
+					 header.iv_len, header.tag,
+					 header.tag_len);
+	memset(key, 0, key_len);
+
+	if (result != 0) {
+		ERROR("File decryption failed (%i)\n", result);
+		return -ENOENT;
+	}
+
+	return result;
+}
+
+static int enc_file_close(io_entity_t *entity)
+{
+	io_close(backend_handle);
+
+	backend_image_spec = (uintptr_t)NULL;
+	entity->info = 0;
+
+	return 0;
+}
+
+/* Exported functions */
+
+/* Register the Encrypted Firmware driver with the IO abstraction */
+int register_io_dev_enc(const io_dev_connector_t **dev_con)
+{
+	int result;
+
+	assert(dev_con != NULL);
+
+	result = io_register_device(&enc_dev_info);
+	if (result == 0)
+		*dev_con = &enc_dev_connector;
+
+	return result;
+}

include/drivers/auth/crypto_mod.h

@@ -13,9 +13,18 @@ enum crypto_ret_value {
 	CRYPTO_ERR_INIT,
 	CRYPTO_ERR_HASH,
 	CRYPTO_ERR_SIGNATURE,
+	CRYPTO_ERR_DECRYPTION,
 	CRYPTO_ERR_UNKNOWN
 };
 
+#define CRYPTO_MAX_IV_SIZE		16U
+#define CRYPTO_MAX_TAG_SIZE		16U
+
+/* Decryption algorithm */
+enum crypto_dec_algo {
+	CRYPTO_GCM_DECRYPT = 0
+};
+
 /*
  * Cryptographic library descriptor
  */
@@ -44,6 +53,15 @@ typedef struct crypto_lib_desc_s {
 			 unsigned int data_len, unsigned char *output);
 #endif /* MEASURED_BOOT */
 
+	/*
+	 * Authenticated decryption. Return one of the
+	 * 'enum crypto_ret_value' options.
+	 */
+	int (*auth_decrypt)(enum crypto_dec_algo dec_algo, void *data_ptr,
+			    size_t len, const void *key, unsigned int key_len,
+			    unsigned int key_flags, const void *iv,
+			    unsigned int iv_len, const void *tag,
+			    unsigned int tag_len);
 } crypto_lib_desc_t;
 
 /* Public functions */
@@ -54,6 +72,11 @@ int crypto_mod_verify_signature(void *data_ptr, unsigned int data_len,
 				void *pk_ptr, unsigned int pk_len);
 int crypto_mod_verify_hash(void *data_ptr, unsigned int data_len,
 			   void *digest_info_ptr, unsigned int digest_info_len);
+int crypto_mod_auth_decrypt(enum crypto_dec_algo dec_algo, void *data_ptr,
+			    size_t len, const void *key, unsigned int key_len,
+			    unsigned int key_flags, const void *iv,
+			    unsigned int iv_len, const void *tag,
+			    unsigned int tag_len);
 
 #if MEASURED_BOOT
 int crypto_mod_calc_hash(unsigned int alg, void *data_ptr,
@@ -61,21 +84,24 @@ int crypto_mod_calc_hash(unsigned int alg, void *data_ptr,
 
 /* Macro to register a cryptographic library */
 #define REGISTER_CRYPTO_LIB(_name, _init, _verify_signature, _verify_hash, \
-							     _calc_hash) \
+			    _calc_hash, _auth_decrypt) \
 	const crypto_lib_desc_t crypto_lib_desc = { \
 		.name = _name, \
 		.init = _init, \
 		.verify_signature = _verify_signature, \
 		.verify_hash = _verify_hash, \
-		.calc_hash = _calc_hash \
+		.calc_hash = _calc_hash, \
+		.auth_decrypt = _auth_decrypt \
 	}
 #else
-#define REGISTER_CRYPTO_LIB(_name, _init, _verify_signature, _verify_hash) \
+#define REGISTER_CRYPTO_LIB(_name, _init, _verify_signature, _verify_hash, \
+			    _auth_decrypt) \
 	const crypto_lib_desc_t crypto_lib_desc = { \
 		.name = _name, \
 		.init = _init, \
 		.verify_signature = _verify_signature, \
-		.verify_hash = _verify_hash \
+		.verify_hash = _verify_hash, \
+		.auth_decrypt = _auth_decrypt \
 	}
 #endif	/* MEASURED_BOOT */
 

include/drivers/auth/mbedtls/mbedtls_config.h

@@ -79,6 +79,12 @@
 #define MBEDTLS_X509_USE_C
 #define MBEDTLS_X509_CRT_PARSE_C
 
+#if TF_MBEDTLS_USE_AES_GCM
+#define MBEDTLS_AES_C
+#define MBEDTLS_CIPHER_C
+#define MBEDTLS_GCM_C
+#endif
+
 /* MPI / BIGNUM options */
 #define MBEDTLS_MPI_WINDOW_SIZE			2
 

include/drivers/io/io_encrypted.h

+/*
+ * Copyright (c) 2020, Linaro Limited. All rights reserved.
+ * Author: Sumit Garg <sumit.garg@linaro.org>
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef IO_ENCRYPTED_H
+#define IO_ENCRYPTED_H
+
+struct io_dev_connector;
+
+int register_io_dev_enc(const struct io_dev_connector **dev_con);
+
+#endif /* IO_ENCRYPTED_H */

include/drivers/io/io_storage.h

@@ -25,6 +25,7 @@ typedef enum {
 	IO_TYPE_MTD,
 	IO_TYPE_MMC,
 	IO_TYPE_STM32IMAGE,
+	IO_TYPE_ENCRYPTED,
 	IO_TYPE_MAX
 } io_type_t;
 

include/export/common/tbbr/tbbr_img_def_exp.h

@@ -85,12 +85,15 @@
 /* Binary with STM32 header */
 #define STM32_IMAGE_ID			U(29)
 
+/* Encrypted image identifier */
+#define ENC_IMAGE_ID			U(30)
+
 /* Define size of the array */
 #if defined(SPD_spmd)
 #define MAX_SP_IDS			U(8)
-#define MAX_NUMBER_IDS			MAX_SP_IDS + U(30)
+#define MAX_NUMBER_IDS			MAX_SP_IDS + U(31)
 #else
-#define MAX_NUMBER_IDS			U(30)
+#define MAX_NUMBER_IDS			U(31)
 #endif
 
 #endif /* ARM_TRUSTED_FIRMWARE_EXPORT_COMMON_TBBR_TBBR_IMG_DEF_EXP_H */

include/plat/common/platform.h

@@ -27,6 +27,7 @@ struct bl_params;
 struct mmap_region;
 struct spm_mm_boot_info;
 struct sp_res_desc;
+enum fw_enc_status_t;
 
 /*******************************************************************************
  * plat_get_rotpk_info() flags
@@ -36,6 +37,15 @@ struct sp_res_desc;
    ROTPK is not deployed */
 #define ROTPK_NOT_DEPLOYED		(1 << 1)
 
+/*******************************************************************************
+ * plat_get_enc_key_info() flags
+ ******************************************************************************/
+/*
+ * Flag used to notify caller that information provided in key buffer is an
+ * identifier rather than an actual key.
+ */
+#define ENC_KEY_IS_IDENTIFIER		(1 << 0)
+
 /*******************************************************************************
  * Function declarations
  ******************************************************************************/
@@ -265,6 +275,9 @@ int plat_set_nv_ctr(void *cookie, unsigned int nv_ctr);
 int plat_set_nv_ctr2(void *cookie, const struct auth_img_desc_s *img_desc,
 		unsigned int nv_ctr);
 int get_mbedtls_heap_helper(void **heap_addr, size_t *heap_size);
+int plat_get_enc_key_info(enum fw_enc_status_t fw_enc_status, uint8_t *key,
+			  size_t *key_len, unsigned int *flags,
+			  const uint8_t *img_id, size_t img_id_len);
 
 /*******************************************************************************
  * Secure Partitions functions

include/tools_share/firmware_encrypted.h

+/*
+ * Copyright (c) 2020, Linaro Limited. All rights reserved.
+ * Author: Sumit Garg <sumit.garg@linaro.org>
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef FIRMWARE_ENCRYPTED_H
+#define FIRMWARE_ENCRYPTED_H
+
+#include <stdint.h>
+
+/* This is used as a signature to validate the encryption header */
+#define ENC_HEADER_MAGIC		0xAA640001U
+
+/* Firmware encryption status flag mask */
+#define FW_ENC_STATUS_FLAG_MASK		0x1
+
+/*
+ * SSK: Secret Symmetric Key
+ * BSSK: Binding Secret Symmetric Key
+ */
+enum fw_enc_status_t {
+	FW_ENC_WITH_SSK = 0,
+	FW_ENC_WITH_BSSK = 1,
+};
+
+#define ENC_MAX_IV_SIZE			16U
+#define ENC_MAX_TAG_SIZE		16U
+#define ENC_MAX_KEY_SIZE		32U
+
+struct fw_enc_hdr {
+	uint32_t magic;
+	uint16_t dec_algo;
+	uint16_t flags;
+	uint16_t iv_len;
+	uint16_t tag_len;
+	uint8_t iv[ENC_MAX_IV_SIZE];
+	uint8_t tag[ENC_MAX_TAG_SIZE];
+};
+
+#endif /* FIRMWARE_ENCRYPTED_H */