Add support for secure upgrade (#2698)

- What I did
Added support for secure upgrade

- How I did it
It includes image signing during build (in sonic buildimage repo) and verification during image install (in sonic-utilities).
HLD can be found in the following PR: sonic-net/SONiC#1024

- How to verify it
Feature is used to allow image was not modified since built from vendor. During installation, image can be verified with a signature attached to it.
In order for image verification - image must be signed - need to provide signing key and certificate (paths in SECURE_UPGRADE_DEV_SIGNING_KEY and SECURE_UPGRADE_DEV_SIGNING_CERT in rules/config) during build , and during image install, need to enable secure boot flag in bios, and signing_certificate should be available in bios.

- Feature dependencies
In order for this feature to work smoothly, need to have secure boot feature implemented as well.
The Secure boot feature will be merged in the near future.

Author: ycoheNvidia

scripts/verify_image_sign.sh

@@ -0,0 +1,60 @@
+#!/bin/sh
+image_file="${1}"
+cms_sig_file="sig.cms"
+lines_for_lookup=50
+DIR="$(dirname "$0")"
+
+. /usr/local/bin/verify_image_sign_common.sh
+
+clean_up ()
+{
+    if  [ -d ${EFI_CERTS_DIR} ]; then rm -rf ${EFI_CERTS_DIR}; fi
+    if  [ -d "${TMP_DIR}" ]; then rm -rf ${TMP_DIR}; fi
+    exit $1
+}
+
+TMP_DIR=$(mktemp -d)
+DATA_FILE="${TMP_DIR}/data.bin"
+CMS_SIG_FILE="${TMP_DIR}/${cms_sig_file}"
+TAR_SIZE=$(head -n $lines_for_lookup $image_file | grep "payload_image_size=" | cut -d"=" -f2- )
+SHARCH_SIZE=$(sed '/^exit_marker$/q' $image_file | wc -c)
+SIG_PAYLOAD_SIZE=$(($TAR_SIZE + $SHARCH_SIZE ))
+# Extract cms signature from signed file
+# Add extra byte for payload
+sed -e '1,/^exit_marker$/d' $image_file | tail -c +$(( $TAR_SIZE + 1 )) > $CMS_SIG_FILE
+# Extract image from signed file
+head -c $SIG_PAYLOAD_SIZE $image_file > $DATA_FILE
+# verify signature with certificate fetched with efi tools
+EFI_CERTS_DIR=/tmp/efi_certs
+[ -d $EFI_CERTS_DIR ] && rm  -rf $EFI_CERTS_DIR
+mkdir $EFI_CERTS_DIR
+efi-readvar -v db -o $EFI_CERTS_DIR/db_efi >/dev/null || 
+{
+    echo "Error: unable to read certs from efi db: $?"
+    clean_up 1
+}
+# Convert one file to der certificates
+sig-list-to-certs $EFI_CERTS_DIR/db_efi $EFI_CERTS_DIR/db >/dev/null||
+{
+    echo "Error: convert sig list to certs: $?"
+    clean_up 1
+}
+for file in $(ls $EFI_CERTS_DIR | grep "db-"); do
+    LOG=$(openssl  x509 -in $EFI_CERTS_DIR/$file -inform der -out $EFI_CERTS_DIR/cert.pem 2>&1)
+    if [ $? -ne 0 ]; then
+        logger "cms_validation: $LOG"
+    fi
+    # Verify detached signature
+    LOG=$(verify_image_sign_common $image_file $DATA_FILE $CMS_SIG_FILE)
+    VALIDATION_RES=$?
+    if [ $VALIDATION_RES -eq 0 ]; then
+        RESULT="CMS Verified OK using efi keys"
+        echo "verification ok:$RESULT"
+        # No need to continue.
+        # Exit without error if any success signature verification.
+        clean_up 0
+    fi
+done
+echo "Failure: CMS signature Verification Failed: $LOG"
+
+clean_up 1

scripts/verify_image_sign_common.sh

@@ -0,0 +1,34 @@
+#!/bin/bash
+verify_image_sign_common() {
+    image_file="${1}"
+    cms_sig_file="sig.cms"
+    TMP_DIR=$(mktemp -d)
+    DATA_FILE="${2}"
+    CMS_SIG_FILE="${3}"
+    
+    openssl version | awk '$2 ~ /(^0\.)|(^1\.(0\.|1\.0))/ { exit 1 }'
+    if [ $? -eq 0 ]; then
+        # for version 1.1.1 and later
+        no_check_time="-no_check_time"
+    else
+        # for version older than 1.1.1 use noattr
+        no_check_time="-noattr"
+    fi
+    
+    # making sure image verification is supported
+    EFI_CERTS_DIR=/tmp/efi_certs
+    RESULT="CMS Verification Failure"
+    LOG=$(openssl cms -verify $no_check_time -noout -CAfile $EFI_CERTS_DIR/cert.pem -binary -in ${CMS_SIG_FILE} -content ${DATA_FILE} -inform pem 2>&1 > /dev/null )
+    VALIDATION_RES=$?
+    if [ $VALIDATION_RES -eq 0 ]; then
+        RESULT="CMS Verified OK"
+        if  [ -d "${TMP_DIR}" ]; then rm -rf ${TMP_DIR}; fi
+        echo "verification ok:$RESULT"
+        # No need to continue.
+        # Exit without error if any success signature verification.
+        return 0
+    fi
+    
+    if  [ -d "${TMP_DIR}" ]; then rm -rf ${TMP_DIR}; fi
+    return 1
+}

setup.py

@@ -156,6 +156,8 @@
         'scripts/memory_threshold_check_handler.py',
         'scripts/techsupport_cleanup.py',
         'scripts/storm_control.py',
+        'scripts/verify_image_sign.sh',
+        'scripts/verify_image_sign_common.sh',
         'scripts/check_db_integrity.py',
         'scripts/sysreadyshow'
     ],

sonic_installer/bootloader/bootloader.py

@@ -75,6 +75,13 @@ def supports_package_migration(self, image):
         """tells if the image supports package migration"""
         return True
 
+    def verify_image_sign(self, image_path):
+        """verify image signature is valid"""
+        raise NotImplementedError
+
+    def is_secure_upgrade_image_verification_supported(self):
+        return False
+
     @classmethod
     def detect(cls):
         """returns True if the bootloader is in use"""

sonic_installer/bootloader/grub.py

@@ -153,6 +153,41 @@ def verify_image_platform(self, image_path):
         # Check if platform is inside image's target platforms
         return self.platform_in_platforms_asic(platform, image_path)
 
+    def is_secure_upgrade_image_verification_supported(self):
+
+        check_if_verification_is_enabled_and_supported_code = '''
+        SECURE_UPGRADE_ENABLED=0
+        if [ -d "/sys/firmware/efi/efivars" ]; then
+            if ! [ -n "$(ls -A /sys/firmware/efi/efivars 2>/dev/null)" ]; then
+                mount -t efivarfs none /sys/firmware/efi/efivars 2>/dev/null
+            fi
+            SECURE_UPGRADE_ENABLED=$(bootctl status 2>/dev/null | grep -c "Secure Boot: enabled")
+        else
+            echo "efi not supported - exiting without verification"
+            exit 1
+        fi
+
+        if [ ${SECURE_UPGRADE_ENABLED} -eq 0 ]; then
+            echo "secure boot not enabled - exiting without image verification"
+            exit 1
+        fi
+        exit 0
+        '''
+        verification_result = subprocess.run(['bash', '-c', check_if_verification_is_enabled_and_supported_code], capture_output=True)
+        click.echo(verification_result.stdout.decode())
+        return verification_result.returncode == 0
+
+    def verify_image_sign(self, image_path):
+        click.echo('Verifying image signature')
+        verification_script_name = 'verify_image_sign.sh'
+        script_path = os.path.join('/usr', 'local', 'bin', verification_script_name)
+        if not os.path.exists(script_path):
+            click.echo("Unable to find verification script in path " + script_path)
+            return False
+        verification_result = subprocess.run([script_path, image_path], capture_output=True)
+        click.echo(verification_result.stdout.decode())
+        return verification_result.returncode == 0
+
     @classmethod
     def detect(cls):
         return os.path.isfile(os.path.join(HOST_PATH, 'grub/grub.cfg'))

sonic_installer/main.py

@@ -511,7 +511,8 @@ def sonic_installer():
 @click.option('-y', '--yes', is_flag=True, callback=abort_if_false,
               expose_value=False, prompt='New image will be installed, continue?')
 @click.option('-f', '--force', '--skip-secure-check', is_flag=True,
-              help="Force installation of an image of a non-secure type than secure running image")
+              help="Force installation of an image of a non-secure type than secure running " +
+              " image, this flag does not affect secure upgrade image verification")
 @click.option('--skip-platform-check', is_flag=True,
               help="Force installation of an image of a type which is not of the same platform")
 @click.option('--skip_migration', is_flag=True,
@@ -576,6 +577,14 @@ def install(url, force, skip_platform_check=False, skip_migration=False, skip_pa
                 "Aborting...", LOG_ERR)
             raise click.Abort()
 
+        if bootloader.is_secure_upgrade_image_verification_supported():
+            echo_and_log("Verifing image {} signature...".format(binary_image_version))
+            if not bootloader.verify_image_sign(image_path):
+                echo_and_log('Error: Failed verify image signature', LOG_ERR)
+                raise click.Abort()
+            else:
+                echo_and_log('Verification successful')
+
         echo_and_log("Installing image {} and setting it as default...".format(binary_image_version))
         with SWAPAllocator(not skip_setup_swap, swap_mem_size, total_mem_threshold, available_mem_threshold):
             bootloader.install_image(image_path)

tests/installer_bootloader_aboot_test.py

@@ -73,3 +73,14 @@ def test_set_fips_aboot():
 
     # Cleanup
     shutil.rmtree(dirpath)
+
+def test_verify_image_sign():
+    bootloader = aboot.AbootBootloader()
+    return_value = None
+    is_supported = bootloader.is_secure_upgrade_image_verification_supported()
+    try:
+        return_value = bootloader.verify_image_sign(exp_image)
+    except NotImplementedError:
+        assert not is_supported
+    else:
+        assert False, "Wrong return value from verify_image_sign, returned" + str(return_value)

tests/installer_bootloader_grub_test.py

@@ -53,3 +53,11 @@ def test_set_fips_grub():
 
     # Cleanup the _tmp_host folder
     shutil.rmtree(tmp_host_path)
+
+def test_verify_image():
+
+    bootloader = grub.GrubBootloader()
+    image = f'{grub.IMAGE_PREFIX}expeliarmus-{grub.IMAGE_PREFIX}abcde'
+    assert not bootloader.is_secure_upgrade_image_verification_supported()
+    # command should fail
+    assert not bootloader.verify_image_sign(image)

tests/installer_bootloader_onie_test.py

@@ -15,3 +15,14 @@ def test_get_current_image(re_search):
     # Test image dir conversion
     onie.re.search().group = Mock(return_value=image)
     assert bootloader.get_current_image() == exp_image
+
+def test_verify_image_sign():
+    bootloader = onie.OnieInstallerBootloader()
+    return_value = None
+    is_supported = bootloader.is_secure_upgrade_image_verification_supported()
+    try:
+        return_value = bootloader.verify_image_sign('some_path.path')
+    except NotImplementedError:
+        assert not is_supported
+    else:
+        assert False, "Wrong return value from verify_image_sign, returned" + str(return_value)

tests/installer_bootloader_uboot_test.py

@@ -94,3 +94,15 @@ def mock_run_command(cmd):
     # Test fips disabled
     bootloader.set_fips(image, False)
     assert not bootloader.get_fips(image)
+
+def test_verify_image_sign():
+    bootloader = uboot.UbootBootloader()
+    image = 'test-image'
+    return_value = None
+    is_supported = bootloader.is_secure_upgrade_image_verification_supported()
+    try:
+        return_value = bootloader.verify_image_sign(image)
+    except NotImplementedError:
+        assert not is_supported
+    else:
+        assert False, "Wrong return value from verify_image_sign, returned" + str(return_value)