op-mode: T861: add "show secure-boot detail" command

"show secure-boot" only reported whether Secure Boot is enabled, not who
signed the running Linux Kernel. An image signed by the VyOS CA could not be
told apart from one signed with a custom Machine Owner Key.

"show secure-boot detail" now lists issuer and subject of the Kernel image
signature certificates. The same information is added to the raw
"show version" data as "secure_boot_detail", issuer and subject delimited by
",". The key is only present when Secure Boot is enabled and a signature
could be read.

2 files changed, 32 insertions, 0 deletions

diff --git a/src/op_mode/secure_boot.py b/src/op_mode/secure_boot.py
index a2d4c9e72..70c4371e6 100755
--- a/src/op_mode/secure_boot.py
+++ b/src/op_mode/secure_boot.py
@@ -18,6 +18,7 @@ import sys
 import vyos.opmode
 
 from vyos.utils.boot import is_uefi_system
+from vyos.utils.system import get_secure_boot_certificates
 from vyos.utils.system import get_secure_boot_state
 
 def _get_raw_data(name=None):
@@ -40,6 +41,26 @@ def show(raw: bool):
     else:
         return _get_formatted_output(sb_data)
 
+def _get_formatted_detail(certificates):
+    out = []
+    for certificate in certificates:
+        out.append(f'Issuer:  {certificate["issuer"]}')
+        out.append(f'Subject: {certificate["subject"]}')
+    return '\n'.join(out)
+
+def show_detail(raw: bool):
+    if not get_secure_boot_state():
+        raise vyos.opmode.UnsupportedOperation('SecureBoot disabled')
+
+    certificates = get_secure_boot_certificates()
+    if not certificates:
+        raise vyos.opmode.DataUnavailable('No Linux Kernel signature certificate found')
+
+    if raw:
+        return certificates
+    else:
+        return _get_formatted_detail(certificates)
+
 if __name__ == "__main__":
     try:
         res = vyos.opmode.run(sys.modules[__name__])
diff --git a/src/op_mode/version.py b/src/op_mode/version.py
index bc74f83fc..09ca62984 100755
--- a/src/op_mode/version.py
+++ b/src/op_mode/version.py
@@ -27,6 +27,7 @@ import vyos.limericks
 
 from vyos.utils.boot import is_uefi_system
 from vyos.system.image import is_running_as_container
+from vyos.utils.system import get_secure_boot_certificates
 from vyos.utils.system import get_secure_boot_state
 
 from jinja2 import Template
@@ -62,6 +63,13 @@ Copyright:        VyOS maintainers and contributors
 {% endif -%}
 """
 
+def _get_secure_boot_detail():
+    """ Return issuer and subject of the running Kernel image signature
+    certificates as "issuer, subject" - multiple signatures are delimited by
+    "; ". Returns None if no signature could be read. """
+    certificates = get_secure_boot_certificates()
+    return '; '.join(f'{c["issuer"]}, {c["subject"]}' for c in certificates) or None
+
 def _get_raw_data(funny=False):
     version_data = vyos.version.get_full_version_data()
     # A container has no firmware of its own - it is not booted at all, thus
@@ -74,6 +82,9 @@ def _get_raw_data(funny=False):
             version_data["secure_boot"] = "disabled"
             if get_secure_boot_state():
                 version_data["secure_boot"] = "enabled"
+                detail = _get_secure_boot_detail()
+                if detail:
+                    version_data["secure_boot_detail"] = detail
 
     if funny:
         version_data["limerick"] = vyos.limericks.get_random()