SWW_APPS: an app's Core Rule Set fixes apply only to the hostnames that serve it (closes #220)

Each app's fixes are one .conf file, whose first rule skips the rest
unless Inspect sets tx.app_<name>, and one entry in apps. SWW_APPS names
each hostname's apps. A hostname gets only its apps' fixes; while
SWW_APPS is unset, every hostname gets every app's fixes.

A hostname in SWW_APPS that is not a DNS name, such as *.example.com,
stops the start. Unset, SWW_APPS is logged at start as null; set
empty, as "".

Model: opus-5-5

internal/coreruleset/mediawiki.conf

@@ -1,4 +1,4 @@
-# The eleventh change: on MediaWiki's paths, some fields skip the rules that
+# MediaWiki's fixes: on MediaWiki's paths, some fields skip the rules that
 # refused ordinary MediaWiki requests there. They are the fields where MediaWiki
 # sends a search, a title, a name, a file name, an address, a summary or a
 # reason, and the fields that hold wikitext. Each exclusion runs with the
@@ -21,6 +21,13 @@
 #   932250: ls -la
 #   932260: python3
 
+# Unless SWW_APPS lists mediawiki for the request's hostname, every rule below
+# is skipped. Inspect sets tx.app_mediawiki when it does.
+# The skip reaches only phase 1, so a rule of a later phase must check
+# tx.app_mediawiki itself.
+SecRule &TX:app_mediawiki "@eq 0" \
+    "id:900890,phase:1,pass,nolog,skipAfter:END_MEDIAWIKI"
+
 # The pages and their titles, the searches, and the special pages' fields
 # for a page, a user, a file or an address:
 #   title: /index.php?title=Python3_notes&action=history
@@ -198,10 +205,12 @@ SecRule REQUEST_FILENAME "@rx ^/(?:w/)?index\.php(?:$|/.)|^/wiki/" \
 # This rule is in phase 2, because a phase 1 rule runs before the body is read
 # and cannot see what wpTitles holds. It checks that the body sends wpTitles
 # once, since it would otherwise skip these rules for a second wpTitles
-# holding a command.
+# holding a command. It checks tx.app_mediawiki, since the skip above does not
+# reach phase 2.
 SecRule REQUEST_FILENAME "@rx ^/(?:w/)?index\.php(?:$|/.)|^/wiki/" \
     "id:900916,phase:2,pass,nolog,chain"
     SecRule REQUEST_FILENAME|ARGS_GET_NAMES "@rx ^/(?:w/)?index\.php/.|^/wiki/|^title$" "chain"
+    SecRule &TX:app_mediawiki "@eq 1" "chain"
     SecRule &ARGS_GET:wpTitles "@eq 0" "chain"
     SecRule &ARGS_POST:wpTitles "@eq 1" "chain"
     SecRule ARGS_POST:wpTitles "!@rx [;|&`{]" \
@@ -210,3 +219,5 @@ SecRule REQUEST_FILENAME "@rx ^/(?:w/)?index\.php(?:$|/.)|^/wiki/" \
         ctl:ruleRemoveTargetById=932235;ARGS:wpTitles,\
         ctl:ruleRemoveTargetById=932260;ARGS:wpTitles,\
         ctl:ruleRemoveTargetById=932380;ARGS:wpTitles"
+
+SecMarker END_MEDIAWIKI