binman: add CST backend selection for i.MX8M signing

Add support for setting the CST backend, both via DT property and
CST_BACKEND environment variable. The CST currently supports two
backends, 'ssl' and 'pkcs11', with 'ssl' being the default when
CST tool is invoked without any -b parameter. Keep 'ssl' backend
as the default, but explicitly pass it via the '-b' parameter,
unless the user selects 'pkcs11' via either method.

Signed-off-by: Marek Vasut <marex@nabladev.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

doc/imx/habv4/guides/mx8m_spl_secure_boot.txt

@@ -167,17 +167,25 @@ The nxp-imx8mcst etype is configurable using either DT properties or environment
 variables. The following DT properties and environment variables are supported.
 Note that environment variables override DT properties.
 
-+--------------------+-----------+------------------------------------------------------------------+
-| DT property        | Variable  | Description                                                      |
-+====================+===========+==================================================================+
-| nxp,loader-address |           | SPL base address                                                 |
-+--------------------+-----------+------------------------------------------------------------------+
-| nxp,srk-table      | SRK_TABLE | full path to SRK_1_2_3_4_table.bin                               |
-+--------------------+-----------+------------------------------------------------------------------+
-| nxp,csf-crt        | CSF_KEY   | full path to the CSF Key CSF1_1_sha256_4096_65537_v3_usr_crt.pem |
-+--------------------+-----------+------------------------------------------------------------------+
-| nxp,img-crt        | IMG_KEY   | full path to the IMG Key IMG1_1_sha256_4096_65537_v3_usr_crt.pem |
-+--------------------+-----------+------------------------------------------------------------------+
++--------------------+-------------+------------------------------------------------------------------+
+| DT property        | Variable    | Description                                                      |
++====================+=============+==================================================================+
+| nxp,loader-address |             | SPL base address                                                 |
++--------------------+-------------+------------------------------------------------------------------+
+| nxp,srk-table      | SRK_TABLE   | full path to SRK_1_2_3_4_table.bin                               |
++--------------------+-------------+------------------------------------------------------------------+
+| nxp,csf-crt        | CSF_KEY     | full path to the CSF Key CSF1_1_sha256_4096_65537_v3_usr_crt.pem |
++--------------------+-------------+------------------------------------------------------------------+
+| nxp,img-crt        | IMG_KEY     | full path to the IMG Key IMG1_1_sha256_4096_65537_v3_usr_crt.pem |
++--------------------+-------------+------------------------------------------------------------------+
+| nxp,fast-auth      |             | enable fast authentication method                                |
++--------------------+-------------+------------------------------------------------------------------+
+| nxp,srk-crt        | SRK_KEY     | full path to the SRK Key SRK1_sha256_4096_65537_v3_ca_crt.pem    |
++--------------------+-------------+------------------------------------------------------------------+
+| nxp,unlock         |             | unlock CAAM in SPL                                               |
++--------------------+-------------+------------------------------------------------------------------+
+| nxp,cst-backend    | CST_BACKEND | CST tool backend, default is 'ssl', or selectable 'pkcs11'       |
++--------------------+-------------+------------------------------------------------------------------+
 
 Environment variables can be set as follows to point the build process
 to external key material:

tools/binman/etype/nxp_imx8mcst.py

@@ -65,6 +65,13 @@ class Entry_nxp_imx8mcst(Entry_mkimage):
 
     Properties / Entry arguments:
         - nxp,loader-address - loader address (SPL text base)
+        - nxp,srk-table - full path to SRK_1_2_3_4_table.bin
+        - nxp,csf-crt - full path to the CSF Key CSF1_1_sha256_4096_65537_v3_usr_crt.pem
+        - nxp,img-crt - full path to the IMG Key IMG1_1_sha256_4096_65537_v3_usr_crt.pem
+        - nxp,fast-auth - enable fast authentication method
+        - nxp,srk-crt - full path to the SRK Key SRK1_sha256_4096_65537_v3_ca_crt.pem
+        - nxp,unlock - unlock CAAM in SPL
+        - nxp,cst-backend - CST tool backend, default is 'ssl', or selectable 'pkcs11'
     """
 
     def __init__(self, section, etype, node):
@@ -90,6 +97,10 @@ class Entry_nxp_imx8mcst(Entry_mkimage):
                 'SRK_KEY', fdt_util.GetString(self._node, 'nxp,srk-crt',
                                               f'SRK1_{KEY_NAME}.pem'))
 
+        self.backend = os.getenv(
+            'CST_BACKEND', fdt_util.GetString(self._node, 'nxp,cst-backend',
+                                              'ssl'))
+
         self.unlock = fdt_util.GetBool(self._node, 'nxp,unlock')
         self.ReadEntries()
 
@@ -161,8 +172,14 @@ class Entry_nxp_imx8mcst(Entry_mkimage):
         with open(cfg_fname, 'w') as cfgf:
             config.write(cfgf)
 
+        # SSL is the default backend, PKCS11 backend is optional
+        if self.backend == "pkcs11":
+            cst_backend = "pkcs11"
+        else:
+            cst_backend = "ssl"
+
         output_fname = tools.get_output_filename(f'nxp.csf-output-blob.{uniq}')
-        args = ['-i', cfg_fname, '-o', output_fname]
+        args = ['-i', cfg_fname, '-o', output_fname, '-b', cst_backend]
         if self.cst.run_cmd(*args) is not None:
             outdata = tools.read_file(output_fname)
             # fixme: 0x2000 should be CONFIG_CSF_SIZE

tools/binman/ftest.py

@@ -8029,6 +8029,21 @@ fdt         fdtmap                Extract the devicetree blob from the fdtmap
         err = stderr.getvalue()
         self.assertRegex(err, "Image 'image'.*missing bintools.*: cst")
 
+    def testNxpImx8mCSTPKCS11(self):
+        """Test CST signing with IVT-format input (pkcs11 auth, no unlock)"""
+        # Create fake IVT blob: magic(4) + padding(20) + signsize_addr(4)
+        # + padding(36) = 64 bytes
+        ivt_data = struct.pack('<I', 0x412000d1)
+        ivt_data += b'\x00' * 20
+        ivt_data += struct.pack('<I', 0)
+        ivt_data += b'\x00' * 36
+        self._MakeInputFile('imx8m-ivt.bin', ivt_data)
+        with terminal.capture() as (_, stderr):
+            self._DoTestFile('vendor/nxp_imx8_csf_pkcs11.dts',
+                             force_missing_bintools='cst')
+        err = stderr.getvalue()
+        self.assertRegex(err, "Image 'image'.*missing bintools.*: cst")
+
     def testNxpImx8mCSTFastAuth(self):
         """Test CST signing with fast-auth mode, unlock, and FIT format"""
         # FIT magic covers the FIT-signing path; fast-auth/unlock cover the

tools/binman/test/vendor/nxp_imx8_csf_pkcs11.dts

@@ -0,0 +1,27 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+/dts-v1/;
+
+/ {
+	#address-cells = <1>;
+	#size-cells = <1>;
+
+	binman {
+		nxp-imx8mcst {
+			args;
+			nxp,loader-address = <0x10>;
+			nxp,cst-backend = "pkcs11";
+
+			blob {
+				filename = "imx8m-ivt.bin";
+			};
+
+			imagename {
+				type = "section";
+
+				u-boot {
+				};
+			};
+		};
+	};
+};