When downgrading the postrm deb script is run as an upgrade.

This works fine with newer versions of Wazuh that follow the same paths structure.

Older versions (ones with ossec group and user) require that we restore that expected
paths and ownership.

debs/SPECS/wazuh-agent/debian/postrm

@@ -51,6 +51,37 @@ case "$1" in
     ;;
 
     upgrade)
+        # If the upgrade downgrades to earlier versions, restore ownership
+        if command -v ${DIR}/bin/ossec-control > /dev/null 2>&1; then
+
+            OSMYSHELL="/sbin/nologin"
+
+            if [ -f ${DIR}/queue/sockets/.agent_info ]; then
+                mv ${DIR}/queue/sockets/.agent_info ${DIR}/queue/ossec/
+            fi
+
+            if ! getent group ossec > /dev/null 2>&1; then
+                addgroup --system ossec > /dev/null 2>&1
+            fi
+
+            if ! getent passwd ossec > /dev/null 2>&1; then
+                adduser --system --home /var/ossec --shell ${OSMYSHELL} --ingroup ossec ossec > /dev/null 2>&1
+            fi
+
+            find ${DIR} ! -group root -exec chgrp ossec {} \; > /dev/null 2>&1
+            find ${DIR} ! -user root -exec chown ossec {} \; > /dev/null 2>&1
+
+            # delete wazuh user and group
+            if getent passwd wazuh > /dev/null 2>&1; then
+                deluser wazuh
+            fi
+
+            if getent group wazuh > /dev/null 2>&1; then
+                delgroup wazuh
+            fi
+        fi
+
+        exit 0
 
     ;;