[202211_SPC4] Secure upgrade v2 sonic-net#2698

Author: DavidZagury

scripts/verify_image_sign.sh

@@ -0,0 +1,75 @@
+#!/bin/sh
+image_file="${1}"
+cms_sig_file="sig.cms"
+lines_for_lookup=50
+SECURE_UPGRADE_ENABLED=0
+DIR="$(dirname "$0")"
+if [ -d "/sys/firmware/efi/efivars" ]; then
+    if ! [ -n "$(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 0
+fi
+
+. /usr/local/bin/verify_image_sign_common.sh
+
+if [ ${SECURE_UPGRADE_ENABLED} -eq 0 ]; then
+    echo "secure boot not enabled - exiting without image verification"
+    exit 0
+fi
+
+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 +75,10 @@ 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"""
+        return True
+
     @classmethod
     def detect(cls):
         """returns True if the bootloader is in use"""

sonic_installer/bootloader/grub.py

@@ -153,6 +153,17 @@ 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 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(str(verification_result.stdout) + " " + str(verification_result.stderr))
+        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()
 
+        # Calling verification script by default - signature will be checked if enabled in bios
+        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)
@@ -958,5 +967,6 @@ def verify_next_image():
         sys.exit(1)
     click.echo('Image successfully verified')
 
+
 if __name__ == '__main__':
     sonic_installer()

tests/installer_bootloader_aboot_test.py

@@ -73,3 +73,8 @@ def test_set_fips_aboot():
 
     # Cleanup
     shutil.rmtree(dirpath)
+
+def test_verify_image_sign():
+    bootloader = aboot.AbootBootloader()
+
+    assert bootloader.verify_image_sign(exp_image) == True

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'
+
+    # command should fail
+    assert not bootloader.verify_image_sign(image)

tests/installer_bootloader_onie_test.py

@@ -15,3 +15,7 @@ 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()
+    assert bootloader.verify_image_sign('some_path.path') == True

tests/installer_bootloader_uboot_test.py

@@ -94,3 +94,9 @@ 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'
+    # Test convertion image dir to image name
+    assert bootloader.verify_image_sign(image) == True