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 and one entry in apps. They apply
only while Inspect has set the app's transaction variable, such as
tx.app_gitea. 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

README.md

@@ -280,6 +280,7 @@ Every setting the code reads, with its default:
 | `SWW_WAF_EXEMPT_PATHS`                   | empty                                                                                    | Path prefixes the Core Rule Set does not inspect.                                                                                                                                                                                                               |
 | `SWW_WAF_BODY_LIMIT`                     | `off`                                                                                    | How much of a request body the Core Rule Set reads, a size up to `64K`; `off` reads none.                                                                                                                                                                       |
 | `SWW_CORE_RULE_SET_EXCLUSIONS_FILE`      | unset                                                                                    | A file of Core Rule Set exclusions, as Coraza directives, that switch rules off for some fields or paths only.                                                                                                                                                  |
+| `SWW_APPS`                               | unset                                                                                    | The apps each hostname serves, `drupal`, `gitea`, `mediawiki` or `wordpress`, such as `git.example.com:gitea;blog.example.com:wordpress`; only those apps' fixes apply there. Unset, every app's fixes apply to every hostname.                                 |
 | `SWW_BLOCKLIST_URLS`                     | empty                                                                                    | Blocklists to fetch, text files of addresses and netblocks one to a line, such as `https://www.spamhaus.org/drop/drop.txt`.                                                                                                                                     |
 | `SWW_BLOCKLIST_REFRESH`                  | `24h`                                                                                    | How long after a list was last tried it is fetched again, `1h` or more.                                                                                                                                                                                         |
 | `SWW_BLOCKLIST_ACTION`                   | `deny`                                                                                   | What a client on a blocklist gets: `deny`, `limit:<percent>` of every limit, or `log`.                                                                                                                                                                          |
@@ -581,22 +582,24 @@ client's limits by tag. See "Request tags" in [`SPEC.md`](SPEC.md).
   headers of every request, and no body unless `SWW_WAF_BODY_LIMIT` is set. In
   front of a code forge, bodies carry what people write and publish, which the
   rules take for attacks.
-- `smallwebwaf` changes the Core Rule Set in eleven ways so that ordinary
+- `smallwebwaf` changes the Core Rule Set in six ways so that it lets ordinary
-  requests get through to a code forge, to WordPress, to Drupal and to
+  requests to a code forge through, such as git over HTTP and sign-in through
-  MediaWiki. They include git over HTTP and sign-in through Git Credential
+  Git Credential Manager. No setting undoes the changes; "Attack detection" in
-  Manager on a code forge, and saving a post from the block editor on WordPress.
-  On gitea's own paths, its searches, file names and branch names get through
-  too. On WordPress's own paths, its searches, names and file names do. On
-  Drupal's own paths, the page to return to, its searches and its names get
-  through too. On MediaWiki's own paths, its searches, page titles, names and
-  wikitext do. No setting undoes the changes; "Attack detection" in
   [`SPEC.md`](SPEC.md) lists them.
-- These apps work out of the box at the default settings, and their recorded
+- Each supported app also has its own fixes, which let its ordinary requests
-  ordinary requests pass the Core Rule Set:
+  through. Its recorded ordinary requests pass the Core Rule Set at the default
-    - gitea;
+  settings. The supported apps, by their names in `SWW_APPS`, are:
-    - WordPress;
+    - `gitea`, whose fixes let its searches, file names and branch names
-    - Drupal;
+      through;
-    - MediaWiki.
+    - `wordpress`, whose fixes let through its searches, its names, its file
+      names and a post saved from the block editor;
+    - `drupal`, whose fixes let through the page to return to, its searches and
+      its names;
+    - `mediawiki`, whose fixes let through its searches, its page titles, its
+      names and its wikitext.
+- `SWW_APPS` names the apps each hostname serves. A hostname gets only its own
+  apps' fixes, and a hostname it does not list gets none. Unset, every app's
+  fixes apply to every hostname.
 - `SWW_CORE_RULE_SET_EXCLUSIONS_FILE` switches single rules off for an app's own
   fields or paths.
 - Rule files are plain text, one rule to a line, edited by hand and read again

SPEC.md

@@ -81,8 +81,8 @@ to them.
       of bans is full.
     - `internal/rules`: reads the rule files at start and again when they
       change, and tells which rules a request matches.
-    - `internal/coreruleset`: the Core Rule Set, with the eleven changes listed
+    - `internal/coreruleset`: the Core Rule Set, with the six changes and the
-      under "Attack detection", as Coraza directives.
+      apps' fixes listed under "Attack detection", as Coraza directives.
     - `internal/lookup`: looks clients up through GeoJS or in the lookup
       database.
     - `internal/reputation`: fetches the lists, asks the DNS blocklists and
@@ -676,8 +676,8 @@ files, the limits and the bans still apply to the client that sends it.
 - `SWW_CORE_RULE_SET_EXCLUSIONS_FILE` names a file of exclusions, written as
   Coraza directives. An exclusion switches one rule off for some fields or paths
   only, where `SWW_WAF_DISABLED_RULES` switches it off everywhere. The file
-  holds an app's own exclusions; the eighth to eleventh changes below hold
+  holds an app's own exclusions; the apps' fixes below hold gitea's,
-  gitea's, WordPress's, Drupal's and MediaWiki's.
+  WordPress's, Drupal's and MediaWiki's.
     - `discriminator` loads the file after `smallwebwaf`'s own setup rules and
       before the Core Rule Set's rules. The Core Rule Set loads its own
       `REQUEST-900-EXCLUSION-RULES-BEFORE-CRS.conf` at the same point.
@@ -723,9 +723,9 @@ files, the limits and the bans still apply to the client that sends it.
     scanner from an ordinary client. In front of a code forge, registry and git
     clients get `404` and `401` by design, hundreds of times a minute.
 
-`smallwebwaf` changes the Core Rule Set 4.25.0 in eleven ways, since in front of
+`smallwebwaf` changes the Core Rule Set 4.25.0 in six ways, since in front of
-gitea, WordPress, Drupal and MediaWiki it would otherwise refuse ordinary
+gitea it would otherwise refuse ordinary requests. The changes hold in front of
-requests. The changes hold in front of every app, and no setting undoes them:
+every app, and no setting undoes them:
 
 1. `PUT`, `PATCH` and `DELETE` are allowed methods besides `GET`, `HEAD`, `POST`
    and `OPTIONS`. APIs, container image pushes and package uploads use them.
@@ -742,8 +742,52 @@ requests. The changes hold in front of every app, and no setting undoes them:
    and tea, which gitea registers for OAuth sign-in, ask to be sent back to
    `http://127.0.0.1` on the user's own machine. The server never fetches that
    address.
-4. Ten query parameters are not checked against the Core Rule Set's lists of
+4. `Referer` is not checked for a Unix command given without arguments (932340),
-   system files (930120), shell paths (932160) and command names (932260):
+   for Java starting a process (944110) or for a Java class name (944130).
+   `Referer` names the page a request comes from, on everything that page loads
+   and on every link followed from it. The Core Rule Set takes some page
+   addresses for attacks:
+    - a search for `env`;
+    - OpenJDK's `Runtime.java`, whose path holds both `runtime` and `java.`;
+    - a file named `java.lang.String.md`.
+
+    Every request from such a page would be refused. `Referer` keeps the other
+    rules, except after some gitea searches (gitea's fixes). An app that passes
+    `Referer` to a shell must check it itself.
+
+5. Responses are not inspected. A raw file from a repository, such as a shell
+   script, looks to the response rules like source code leaking from the server.
+6. The `from` parameter of a container registry's upload path,
+   `/v2/<image>/blobs/uploads/`, is not checked for command names (932260). When
+   a push reuses a layer, `from` names the image the layer comes from. An image
+   such as `owner/python3-app` would have that push refused.
+
+Each supported app also has its own fixes, which let its ordinary requests
+through. `SWW_APPS` says which hostnames get which app's fixes:
+
+- `SWW_APPS` holds entries separated by semicolons. Each is a hostname, a colon,
+  then one or more apps separated by commas, for example
+  `git.example.com:gitea;blog.example.com:wordpress`.
+- The request's `Host` is matched by exact name, without its port and without
+  regard to case. There are no wildcards.
+- A hostname not listed gets no app's fixes, so every rule checks it in full.
+  Set empty, `SWW_APPS` lists no hostname.
+- Unset, every app's fixes hold for every hostname. An app's fixes then weaken
+  the check of any other app that serves the same paths or fields.
+- Any of these mistakes stops the start:
+    - an unknown app;
+    - a hostname that is not a DNS name, such as `*.example.com`;
+    - a hostname listed twice;
+    - an app listed twice for one hostname;
+    - an entry without a colon.
+
+The apps supported are `drupal`, `gitea`, `mediawiki` and `wordpress`. Each
+app's fixes are in one file, such as `internal/coreruleset/gitea.conf`, and one
+entry of `apps` in `internal/coreruleset/coreruleset.go`. gitea's fixes are:
+
+1. Ten query parameters are not checked against the Core Rule Set's lists of
+   system files (930120), shell paths (932160) and command names (932260), on
+   any path:
     - `path`, `files`, `skip-to` and `sub_path`;
     - `ref`, `sha`, `branch` and `workflow`;
     - `artifactName` and `redirect_to`.
@@ -756,42 +800,19 @@ requests. The changes hold in front of every app, and no setting undoes them:
     catch reaches the app, such as the command `|cat /etc/passwd`. Path
     traversal, SQL and script injection, and PHP, Java and Node.js code are
     still refused there. Other parameters keep all three rules, except on the
-    gitea, WordPress, Drupal and MediaWiki paths the eighth to eleventh changes
+    paths named in gitea's third fix, in WordPress's fixes, in Drupal's fixes
-    name. An app that uses one of these parameters as a file on the server, or
+    and in MediaWiki's fixes.
-    passes it to a shell, must check the value itself. A rule file can refuse it
-    instead.
 
-5. Two cookies are left out, and `Referer` keeps fewer rules:
+2. The Core Rule Set reads the request without the `gitea_flash` and
-    - The Core Rule Set reads the request without the `gitea_flash` and
    `redirect_to` cookies. gitea puts a message naming what was just done into
-      `gitea_flash`. It puts into `redirect_to` the page to return to after
+   `gitea_flash`. It puts into `redirect_to` the page to return to after signing
-      signing in. The Core Rule Set takes file names in them, such as
+   in. The Core Rule Set takes file names in them, such as `package.json`, for
-      `package.json`, for attacks. A browser sends such a cookie with every
+   attacks. A browser sends such a cookie with every request until gitea
-      request until gitea replaces it. gitea cannot replace it while those
+   replaces it. gitea cannot replace it while those requests are refused, so one
-      requests are refused, so one refusal would keep the browser out of the
+   refusal would keep the browser out of the whole site. gitea shows the message
-      whole site. gitea shows the message with any script removed and returns
+   with any script removed and returns only to its own pages. Every other cookie
-      only to its own pages. Every other cookie is read in full. An app that
+   is read in full.
-      reads a cookie of either name must check it itself.
+3. On gitea's paths, some fields skip the rules that refused ordinary gitea
-    - `Referer` is not checked for a Unix command given without arguments
-      (932340), for Java starting a process (944110) or for a Java class name
-      (944130). `Referer` names the page a request comes from, on everything
-      that page loads and on every link followed from it. The Core Rule Set
-      takes some page addresses for attacks:
-        - a search for `env`;
-        - OpenJDK's `Runtime.java`, whose path holds both `runtime` and `java.`;
-        - a file named `java.lang.String.md`.
-
-        Every request from such a page would be refused. `Referer` keeps the
-        other rules, except after some gitea searches (the eighth change). An
-        app that passes `Referer` to a shell must check it itself.
-
-6. Responses are not inspected. A raw file from a repository, such as a shell
-   script, looks to the response rules like source code leaking from the server.
-7. The `from` parameter of a container registry's upload path,
-   `/v2/<image>/blobs/uploads/`, is not checked for command names (932260). When
-   a push reuses a layer, `from` names the image the layer comes from. An image
-   such as `owner/python3-app` would have that push refused.
-8. On gitea's paths, some fields skip the rules that refused ordinary gitea
    requests there. They are the fields where gitea sends a search, a file name
    or a branch name. `internal/coreruleset/gitea.conf` lists each rule and the
    request it refused. The fields are:
@@ -809,8 +830,7 @@ requests. The changes hold in front of every app, and no setting undoes them:
         - packages.
 
         A user's or an organisation's page is any path of one segment, so on
-        every such path, on any app, `q` skips these three rules, for example on
+        every such path `q` skips these three rules, for example on `/search`.
-        `/search`.
 
         Some of these searches also skip the rule for Java class names (944130),
         which refused `org.apache.commons.logging`.
@@ -848,43 +868,41 @@ requests. The changes hold in front of every app, and no setting undoes them:
       `actions/upload-artifact@v3` (920450).
 
     Elsewhere these fields keep every rule. The paths are those of gitea at the
-    site root. An app other than gitea that serves one of them must check these
+    site root.
-    fields itself.
+
+WordPress's fixes: on WordPress's paths, some fields skip the rules that refused
+ordinary WordPress requests there. `internal/coreruleset/wordpress.conf` lists
+each rule and the request it refused. The REST API has four addresses:
 
-9. On WordPress's paths, some fields skip the rules that refused ordinary
-   WordPress requests there. `internal/coreruleset/wordpress.conf` lists each
-   rule and the request it refused. The REST API has four addresses:
 - `/wp-json/...`
 - `/index.php/wp-json/...`
 - `/index.php?rest_route=/...`
 - `/?rest_route=/...`
 
 The fields are:
-    - The header `X-HTTP-Method-Override` on any address of the REST API
+
-      (920450). The block editor saves a post with `POST` and names `PUT` in
+- The header `X-HTTP-Method-Override` on any address of the REST API (920450).
-      this header.
+  The block editor saves a post with `POST` and names `PUT` in this header.
-    - Three groups of fields skip the rules on system files and commands
+- Three groups of fields skip the rules on system files and commands (930120,
-      (930120, 932120, 932250, 932260). The fields hold searches, names and
+  932120, 932250, 932260). The fields hold searches, names and addresses of
-      addresses of WordPress's own pages, and any of them can hold any word. The
+  WordPress's own pages, and any of them can hold any word. The groups are:
-      groups are:
     - On all of `/wp-admin/` and on `/wp-login.php`:
         - the searches `s`, `search`, `q` and `term`;
-            - the names `tag`, `category_name`, `plugin`, `checked[]`, `theme`
+        - the names `tag`, `category_name`, `plugin`, `checked[]`, `theme` and
-              and `stylesheet`;
+          `stylesheet`;
         - the name of a plugin's settings page in `page`;
-            - the addresses `url`, `return`, `redirect_to`, `wp_http_referer`
+        - the addresses `url`, `return`, `redirect_to`, `wp_http_referer` and
-              and `_wp_http_referer`.
+          `_wp_http_referer`.
     - On every REST API route under `/wp/v2/` and on the route
       `/oembed/1.0/embed`: `search`, `term`, `slug` and `url`.
-        - On `/`, `/index.php`, `/page/N/` and `/index.php/page/N/`: `s` and
+    - On `/`, `/index.php`, `/page/N/` and `/index.php/page/N/`: `s` and `tag`.
-          `tag`.
 
     The addresses of the first group also skip the rule on Unix commands
     (932235), because an address repeats the search it came from. The other
     fields of the groups keep that rule.
 
-    - On all of `/wp-admin/` and on `/wp-login.php`, these names skip the lists
+- On all of `/wp-admin/` and on `/wp-login.php`, these names skip the lists of
-      of PowerShell commands and command names (932120, 932260):
+  PowerShell commands and command names (932120, 932260):
     - the name of a template in `p` and `postId` of the site editor;
     - the name of a plugin to install in `slug`.
 
@@ -892,42 +910,40 @@ requests. The changes hold in front of every app, and no setting undoes them:
 
 - `url` on the REST API routes `/wp-block-editor/v1/url-details` and
   `/oembed/1.0/proxy`, for the lists of system files and PowerShell commands
-      (930120, 932120). The block editor's link previews and embeds send an
+  (930120, 932120). The block editor's link previews and embeds send an address
-      address in this field.
+  in this field.
 
-    - `_wp_http_referer` on `/wp-admin/upload.php`, for a Unix command given
+- `_wp_http_referer` on `/wp-admin/upload.php`, for a Unix command given without
-      without arguments (932340). The media list's own address ends in `&ps`.
+  arguments (932340). The media list's own address ends in `&ps`.
-    - `file` on `/wp-admin/plugin-editor.php` and `/wp-admin/theme-editor.php`,
+- `file` on `/wp-admin/plugin-editor.php` and `/wp-admin/theme-editor.php`, for
-      for the lists of system files, shell paths, command names and JavaScript
+  the lists of system files, shell paths, command names and JavaScript names
-      names (930120, 932120, 932160, 932260, 941180).
+  (930120, 932120, 932160, 932260, 941180).
-    - These fields of a body. Each applies only when the query has no parameter
+- These fields of a body. Each applies only when the query has no parameter of
-      of that name, so it matters only while `SWW_WAF_BODY_LIMIT` is set:
+  that name, so it matters only while `SWW_WAF_BODY_LIMIT` is set:
-        - `content` of a post, a page, a template or a template part saved
+    - `content` of a post, a page, a template or a template part saved through
-          through the REST API. It holds HTML and any code it shows.
+      the REST API. It holds HTML and any code it shows.
     - `content` of a reply to a comment sent to `admin-ajax.php`.
-        - `newcontent` of a plugin's or a theme's file saved from its editor,
+    - `newcontent` of a plugin's or a theme's file saved from its editor, which
-          which is PHP.
+      is PHP.
     - `pwd` when signing in, for the list of system files (930120).
-        - `title`, `excerpt` and `name` in a JSON body sent to any REST API
+    - `title`, `excerpt` and `name` in a JSON body sent to any REST API route
-          route under `/wp/v2/`, for the rules on system files and commands
+      under `/wp/v2/`, for the rules on system files and commands (930120,
-          (930120, 932120, 932250, 932260).
+      932120, 932250, 932260).
-        - `slug` in a JSON body sent to any REST API route under `/wp/v2/`, for
+    - `slug` in a JSON body sent to any REST API route under `/wp/v2/`, for the
-          the lists of PowerShell commands and command names (932120, 932260).
+      lists of PowerShell commands and command names (932120, 932260).
-        - `url` on `/wp-comments-post.php`, the address of a commenter's site,
+    - `url` on `/wp-comments-post.php`, the address of a commenter's site, for
-          for the lists of system files and PowerShell commands (930120,
+      the lists of system files and PowerShell commands (930120, 932120).
-          932120).
 
-    Elsewhere this change does not apply. The paths are those of WordPress at
+Elsewhere WordPress's fixes do not apply. The paths are those of WordPress at
-    the site root. An app other than WordPress that serves one of them must
+the site root.
-    check these fields itself.
 
-10. On Drupal's paths, some fields skip the rules that refused ordinary Drupal
+Drupal's fixes: on Drupal's paths, some fields skip the rules that refused
-    requests there. `internal/coreruleset/drupal.conf` lists each rule and the
+ordinary Drupal requests there. `internal/coreruleset/drupal.conf` lists each
-    request it refused. These query fields skip the lists of system files and
+rule and the request it refused. These query fields skip the lists of system
-    command names (930120, 932120, 932250, 932260):
+files and command names (930120, 932120, 932250, 932260):
-    - On every page under `/admin`: `title`, `name`, `user`, `filename`,
+
-      `filemime`, `info`, `subject`, `author_name`, `search`, `q` and
+- On every page under `/admin`: `title`, `name`, `user`, `filename`, `filemime`,
-      `destination`.
+  `info`, `subject`, `author_name`, `search`, `q` and `destination`.
 - `destination` on the pages Drupal links to with one, such as these:
     - `/node/1/edit`;
     - `/user/login`;
@@ -940,16 +956,16 @@ requests. The changes hold in front of every app, and no setting undoes them:
     - `/ckeditor5/{editor}/entity-link-suggestions`;
     - `/block-category/autocomplete`.
 - Every `filter[...]` field on `/jsonapi/`.
-    - `name` on `/user/password`, `/media-library` and `/views/ajax`, in the
+- `name` on `/user/password`, `/media-library` and `/views/ajax`, in the query
-      query or a body.
+  or a body.
 
-    `destination` also skips 932230 and 932235, because it holds the address of
+`destination` also skips 932230 and 932235, because it holds the address of a
-    a page of results. `url` on `/media/oembed`, the address of a video, skips
+page of results. `url` on `/media/oembed`, the address of a video, skips only
-    only 930120 and 932120.
+930120 and 932120.
 
 These fields of a body skip the rules that refused them:
-    - On the node, comment and media forms, for 930120, 932120, 932250 and
+
-      932260:
+- On the node, comment and media forms, for 930120, 932120, 932250 and 932260:
     - the title;
     - the summary;
     - the tags;
@@ -972,32 +988,32 @@ requests. The changes hold in front of every app, and no setting undoes them:
     - `description.value`.
 - The title saved through Drupal's JSON format on `/node/{id}`, for the same
   four rules.
-    - The body and comment body on the node and comment forms and through
+- The body and comment body on the node and comment forms and through JSON:API,
-      JSON:API, which hold HTML and any code it shows.
+  which hold HTML and any code it shows.
 - `name` and `pass` when signing in (930120, 932120, 932250, 932260).
 - `name` when resetting a password through Drupal's JSON format on
   `/user/password`, for the same four rules.
 - `mail` in that same reset, for 932120 and 932260 only.
-    - `name` when signing up, editing an account and commenting without an
+- `name` when signing up, editing an account and commenting without an account,
-      account, for the same four rules.
+  for the same four rules.
 - `mail` on those forms, for 930120, 932120 and 932260 only.
 
 These exclusions matter only while `SWW_WAF_BODY_LIMIT` is set. None applies
 when the query has a parameter of the same name.
 
 Elsewhere these fields keep every rule. The paths are those of Drupal at the
-    site root, with or without a language prefix such as `/fr`. Such a prefix is
+site root, with or without a language prefix such as `/fr`. Such a prefix is any
-    any first path segment of two or three lowercase letters, optionally
+first path segment of two or three lowercase letters, optionally followed by a
-    followed by a hyphen and more letters, so `/api` counts too. An app other
+hyphen and more letters, so `/api` counts too.
-    than Drupal that serves one of them must check these fields itself.
 
-11. On MediaWiki's paths, some fields skip the rules that refused ordinary
+MediaWiki's fixes: on MediaWiki's paths, some fields skip the rules that refused
-    MediaWiki requests there. `internal/coreruleset/mediawiki.conf` lists each
+ordinary MediaWiki requests there. `internal/coreruleset/mediawiki.conf` lists
-    rule and the request it refused. These fields skip the lists of system files
+each rule and the request it refused. These fields skip the lists of system
-    and command names (930120, 932120, 932250, 932260), in the query or the
+files and command names (930120, 932120, 932250, 932260), in the query or the
 body:
-    - On MediaWiki's pages, which are `/index.php` and the paths under
+
-      `/index.php/` and `/wiki/`:
+- On MediaWiki's pages, which are `/index.php` and the paths under `/index.php/`
+  and `/wiki/`:
     - the searches `search` and `ilsearch`;
     - the titles `title`, `page` and `target`;
     - `from`, `to` and `prefix`, which limit a list of pages;
@@ -1009,12 +1025,12 @@ requests. The changes hold in front of every app, and no setting undoes them:
     - the searches `search`, `srsearch` and `pssearch`;
     - the titles `titles`, `title`, `page` and `bltitle`;
     - `from` and `to`, the titles of a page being moved;
-        - the starts of lists `apfrom`, `apto`, `apprefix`, `aifrom`,
+    - the starts of lists `apfrom`, `apto`, `apprefix`, `aifrom`, `aiprefix`,
-          `aiprefix`, `aufrom` and `auprefix`;
+      `aufrom` and `auprefix`;
     - `letitle`, the page whose log is listed;
     - `euquery`, an address;
-        - the fields a generator sends in place of the fields above, each with a
+    - the fields a generator sends in place of the fields above, each with a `g`
-          `g` in front:
+      in front:
         - `gsrsearch` and `gpssearch`;
         - `gapfrom`, `gapto` and `gapprefix`;
         - `gaifrom` and `gaiprefix`;
@@ -1025,32 +1041,32 @@ requests. The changes hold in front of every app, and no setting undoes them:
     - `lgname`, `lgpassword`, `username` and `password`, for signing in.
 - `q` on `/rest.php/` and the paths under it.
 
-    `modules` on `/load.php` skips 930120 alone, because it lists the scripts
+`modules` on `/load.php` skips 930120 alone, because it lists the scripts and
-    and styles a page loads.
+styles a page loads.
 
 These fields of a body skip the rules that refused them:
+
 - On MediaWiki's pages, for the same four rules:
     - `wpSummary`, the summary of an edit;
     - `wpUploadDescription`, the description of an uploaded file;
     - `wpName` and `wpPassword`, for signing in;
     - `wpOldTitle`, `wpNewTitleMain` and `wpReason`, for moving a page.
 - `comment` in the JSON body of `/rest.php/`, for the same four rules.
-    - On MediaWiki's pages, for 930120 and 932120 alone, the reasons on the
+- On MediaWiki's pages, for 930120 and 932120 alone, the reasons on the admin
-      admin pages:
+  pages:
     - `wpReason-other`, for blocking a user;
     - `user-reason`, for changing a user's groups;
     - `mwProtect-reason`, for protecting a page.
 - On MediaWiki's pages, `wpTitles`, the list of watched pages that
-      `Special:EditWatchlist/raw` sends, one title per line. It always skips
+  `Special:EditWatchlist/raw` sends, one title per line. It always skips 930120,
-      930120, 932120 and 932250. It skips 932125, 932230, 932235, 932260 and
+  932120 and 932250. It skips 932125, 932230, 932235, 932260 and 932380 only
-      932380 only when it holds no `;`, `|`, `&`, backtick or `{`. A title
+  when it holds no `;`, `|`, `&`, backtick or `{`. A title starting with a
-      starting with a command name, such as `Python3 notes`, passes. So does a
+  command name, such as `Python3 notes`, passes. So does a command alone on a
-      command alone on a line, such as `wget http://example.com/x.sh`. A command
+  line, such as `wget http://example.com/x.sh`. A command such as
-      such as `; wget http://example.com/x.sh` is still refused. So is a list
+  `; wget http://example.com/x.sh` is still refused. So is a list that mixes a
-      that mixes a title holding one of these characters with a title starting
+  title holding one of these characters with a title starting with a command
-      with a command name.
+  name.
-    - The wikitext of a page, which holds templates, tables and any code it
+- The wikitext of a page, which holds templates, tables and any code it shows:
-      shows:
     - `wpTextbox1` on MediaWiki's pages;
     - `text`, `appendtext` and `prependtext` on `/api.php`;
     - `source` in the JSON body of `/rest.php/`.
@@ -1058,21 +1074,24 @@ requests. The changes hold in front of every app, and no setting undoes them:
 These body exclusions matter only while `SWW_WAF_BODY_LIMIT` is set. None
 applies when the query has a parameter of the same name.
 
-    The names of uploaded files skip 932180 on MediaWiki's pages and on
+The names of uploaded files skip 932180 on MediaWiki's pages and on `/api.php`,
-    `/api.php`, so a picture named `Notes on .htaccess.png` can be uploaded.
+so a picture named `Notes on .htaccess.png` can be uploaded. MediaWiki refuses a
-    MediaWiki refuses a file whose extension it does not allow.
+file whose extension it does not allow.
 
-    `/index.php` itself counts as MediaWiki's only when its query has a `title`,
+`/index.php` itself counts as MediaWiki's only when its query has a `title`, as
-    as in `/index.php?title=Main_Page`. WordPress serves `/index.php` too. A
+in `/index.php?title=Main_Page`. WordPress serves `/index.php` too. A wiki
-    wiki without short URLs serves its pages under `/index.php/`, as in
+without short URLs serves its pages under `/index.php/`, as in
 `/index.php/Main_Page`, and its sign-in and upload forms post there.
 
-    Elsewhere these fields keep every rule. The paths are those of MediaWiki at
+Elsewhere these fields keep every rule. The paths are those of MediaWiki at the
-    the site root or under `/w/`. An app other than MediaWiki that serves one of
+site root or under `/w/`.
-    them must check these fields itself.
 
-The parameter and cookie names in these changes are matched without regard to
+Each app's fixes switch rules off for some of its fields and cookies. Any other
-case, as Coraza matches them.
+app on a hostname that gets those fixes must check those fields and cookies
+itself.
+
+The parameter names in these changes and fixes are matched without regard to
+case, and the cookie names exactly.
 
 ### Ban lengths, response and scope
 

docs/settings.md

@@ -255,6 +255,24 @@ the request first.
   a range. So does a directive that removes or changes rules as the file loads,
   such as `SecRuleRemoveById`, since none of the Core Rule Set's rules is loaded
   yet. It has no `_FILE` form.
+- `SWW_APPS` (default unset): the apps each hostname serves. A request gets the
+  fixes of its hostname's apps only (see "Attack detection" in
+  [`SPEC.md`](../SPEC.md)).
+    - Entries are separated by semicolons. Each is a hostname, a colon, then one
+      or more apps separated by commas, for example
+      `git.example.com:gitea;blog.example.com:wordpress`.
+    - The apps supported are `drupal`, `gitea`, `mediawiki` and `wordpress`.
+    - The request's `Host` is matched by exact name, without its port and
+      without regard to case. There are no wildcards.
+    - A hostname not listed gets no app's fixes, so every rule checks it in
+      full. Set empty, `SWW_APPS` lists no hostname.
+    - Unset, every app's fixes apply to every hostname.
+    - Any of these mistakes stops the start:
+        - an unknown app;
+        - a hostname that is not a DNS name, such as `*.example.com`;
+        - a hostname listed twice;
+        - an app listed twice for one hostname;
+        - an entry without a colon.
 - `SWW_ERROR_BURST_THRESHOLD` (default `30`): the most refusals a client may get
   in a minute from a rule file, a trap path or the Core Rule Set, a count or
   `off`. The next one bans the client (see "Attack detection" in `SPEC.md`).

internal/config/config.go

@@ -29,6 +29,7 @@ import (
 
 	"sneak.berlin/go/smallwebwaf/internal/alerts"
 	"sneak.berlin/go/smallwebwaf/internal/anomaly"
+	"sneak.berlin/go/smallwebwaf/internal/coreruleset"
 	"sneak.berlin/go/smallwebwaf/internal/remotelog"
 )
 
@@ -235,6 +236,11 @@ type Config struct {
 	WAFExemptPaths            []string
 	WAFBodyLimit              int64
 	CoreRuleSetExclusionsFile string
+	// Apps are the names of the apps each hostname serves, by hostname in
+	// lowercase (SWW_APPS): a request gets only its hostname's apps' fixes
+	// to the Core Rule Set. Apps is nil while SWW_APPS is unset, and every
+	// request gets every app's fixes.
+	Apps map[string][]string
 	// TrapPaths are the paths a request for which is a clear sign of
 	// attack (SWW_TRAP_PATHS), each starting with / and without a ?.
 	TrapPaths []string
@@ -404,6 +410,11 @@ var (
 	errNotTrapPath = errors.New(
 		"is not a path starting with / and without a ?, such as /wp-login.php",
 	)
+	errNotAppsEntry = errors.New(
+		"is not a hostname, : and a list of apps, such as git.example.com:gitea",
+	)
+	errNotHostname      = errors.New("is not a DNS name such as git.example.com")
+	errNotApp           = errors.New("is not an app sww has fixes for; the apps are")
 	errNotWAFMode       = errors.New("is not off, detect or block")
 	errNotParanoiaLevel = errors.New("is not a paranoia level, from 1 to 4")
 	errNotRuleID        = errors.New(
@@ -577,6 +588,7 @@ func FromEnvironment(
 		WAFBodyLimit:   env.wafBodyLimit("SWW_WAF_BODY_LIMIT", off),
 		CoreRuleSetExclusionsFile: env.filePath(
 			"SWW_CORE_RULE_SET_EXCLUSIONS_FILE"),
+		Apps:                 env.apps("SWW_APPS"),
 		TrapPaths:            env.trapPaths("SWW_TRAP_PATHS"),
 		ErrorBurstThreshold:  env.count("SWW_ERROR_BURST_THRESHOLD", "30"),
 		LogRemoteURL:         env.logRemoteURL("SWW_LOG_REMOTE_URL"),
@@ -832,6 +844,25 @@ func (e *environment) pathPrefixes(name, defaultValue string) []string {
 	return prefixes
 }
 
+// apps reads the setting that is the apps each hostname serves. It is nil
+// while the setting is unset, and logged as null, unlike a setting set
+// empty.
+func (e *environment) apps(name string) map[string][]string {
+	value, set := e.lookup(name)
+	if !set {
+		e.settings = append(e.settings, slog.Any(name, nil))
+
+		return nil
+	}
+
+	e.settings = append(e.settings, slog.String(name, value))
+
+	apps, err := parseApps(value)
+	e.check(name, err)
+
+	return apps
+}
+
 // trapPaths reads the setting that is the list of trap paths. It is empty
 // by default.
 func (e *environment) trapPaths(name string) []string {
@@ -1849,6 +1880,65 @@ func parseTrapPaths(value string) ([]string, error) {
 	return paths, nil
 }
 
+// parseApps reads the apps each hostname serves: entries separated by
+// semicolons, each a hostname, a colon, and a comma-separated list of the
+// names coreruleset.AppNames returns, such as
+// git.example.com:gitea;cloud.example.com:nextcloud,wordpress. Each
+// hostname is a DNS name, without a wildcard. It returns them by hostname
+// in lowercase, since a hostname is matched without regard to case. An
+// empty value lists no hostname.
+func parseApps(value string) (map[string][]string, error) {
+	apps := map[string][]string{}
+
+	if strings.TrimSpace(value) == "" {
+		return apps, nil
+	}
+
+	for entry := range strings.SplitSeq(value, ";") {
+		hostname, list, found := strings.Cut(entry, ":")
+		if !found {
+			return nil, fmt.Errorf("%q %w", entry, errNotAppsEntry)
+		}
+
+		hostname = strings.ToLower(strings.TrimSpace(hostname))
+		if hostname == "" {
+			return nil, fmt.Errorf("%q %w", entry, errNotAppsEntry)
+		}
+
+		if !isZone(hostname) {
+			return nil, fmt.Errorf("%q %w", hostname, errNotHostname)
+		}
+
+		if _, listed := apps[hostname]; listed {
+			return nil, fmt.Errorf("%q %w", hostname, errListedTwice)
+		}
+
+		names, err := parseList(list)
+		if err != nil {
+			return nil, err
+		}
+
+		if len(names) == 0 {
+			return nil, fmt.Errorf("%q %w", entry, errNotAppsEntry)
+		}
+
+		for i, name := range names {
+			if !slices.Contains(coreruleset.AppNames(), name) {
+				return nil, fmt.Errorf("%q %w %s", name, errNotApp,
+					strings.Join(coreruleset.AppNames(), ", "))
+			}
+
+			if slices.Contains(names[:i], name) {
+				return nil, fmt.Errorf("%q %w", name, errListedTwice)
+			}
+		}
+
+		apps[hostname] = names
+	}
+
+	return apps, nil
+}
+
 // parseRuleIDs reads a comma-separated list of the ids of Core Rule Set
 // rules, each a whole number above zero and outside firstSetupRuleID to
 // lastSetupRuleID.
@@ -2455,7 +2545,8 @@ func MaskZoneKey(zone string) string {
 	return masked + "." + rest
 }
 
-// isZone reports whether each label of zone is as parseZones takes it.
+// isZone reports whether each label of zone is as parseZones takes it. It
+// also checks the hostnames of SWW_APPS, which are DNS names too.
 func isZone(zone string) bool {
 	for label := range strings.SplitSeq(zone, ".") {
 		badChar := strings.ContainsFunc(label, func(char rune) bool {

internal/config/config_test.go

@@ -89,6 +89,7 @@ const (
 	wafExemptPaths       = "SWW_WAF_EXEMPT_PATHS"
 	wafBodyLimit         = "SWW_WAF_BODY_LIMIT"
 	exclusionsFile       = "SWW_CORE_RULE_SET_EXCLUSIONS_FILE"
+	apps                 = "SWW_APPS"
 	trapPaths            = "SWW_TRAP_PATHS"
 	errorBurstThreshold  = "SWW_ERROR_BURST_THRESHOLD"
 	logRemoteURL         = "SWW_LOG_REMOTE_URL"
@@ -582,6 +583,100 @@ func TestCoreRuleSetSettings(t *testing.T) {
 	}
 }
 
+// gitea is gitea's name in SWW_APPS.
+const gitea = "gitea"
+
+func TestApps(t *testing.T) {
+	t.Parallel()
+
+	for _, tc := range []struct {
+		env  environment
+		want map[string][]string
+	}{
+		{environment{}, nil},
+		{environment{apps: ""}, map[string][]string{}},
+		{
+			environment{apps: "Git.Example.com:gitea; cloud.example.com : gitea "},
+			map[string][]string{
+				"git.example.com": {gitea}, "cloud.example.com": {gitea},
+			},
+		},
+		{
+			environment{apps: "cloud.example.com:gitea,wordpress"},
+			map[string][]string{"cloud.example.com": {gitea, "wordpress"}},
+		},
+	} {
+		cfg := fromEnvironment(t, tc.env)
+		if !reflect.DeepEqual(cfg.Apps, tc.want) {
+			t.Errorf("%v gave %#v, want %#v", tc.env, cfg.Apps, tc.want)
+		}
+	}
+}
+
+// Unset and set empty, SWW_APPS has opposite effects, so it logs differently.
+func TestUnsetAndEmptyAppsAreLoggedDifferently(t *testing.T) {
+	t.Parallel()
+
+	for _, tc := range []struct {
+		env  environment
+		want string
+	}{
+		{environment{}, `"` + apps + `":null`},
+		{environment{apps: ""}, `"` + apps + `":""`},
+	} {
+		var out bytes.Buffer
+
+		slog.New(slog.NewJSONHandler(&out, nil)).
+			Info("starting", "settings", fromEnvironment(t, tc.env))
+
+		if !strings.Contains(out.String(), tc.want) {
+			t.Errorf("%v logged %s, want %s in it", tc.env, out.String(), tc.want)
+		}
+	}
+}
+
+func TestInvalidAppsStopsTheStart(t *testing.T) {
+	t.Parallel()
+
+	const (
+		notEntry = " is not a hostname, : and a list of apps, " +
+			"such as git.example.com:gitea"
+		notHostname = " is not a DNS name such as git.example.com"
+	)
+
+	for _, tc := range []struct{ value, want string }{
+		{"git.example.com:gitea;blog.example.com", `"blog.example.com"` + notEntry},
+		{"git.example.com:gitea;", `""` + notEntry},
+		{":gitea", `":gitea"` + notEntry},
+		{"git.example.com:", `"git.example.com:"` + notEntry},
+		{"*.example.com:gitea", `"*.example.com"` + notHostname},
+		{"git.example.com/:gitea", `"git.example.com/"` + notHostname},
+		{"git example.com:gitea", `"git example.com"` + notHostname},
+		{
+			"git.example.com:gitea,nextcloud",
+			`"nextcloud" is not an app sww has fixes for; ` +
+				`the apps are drupal, gitea, mediawiki, wordpress`,
+		},
+		{
+			"git.example.com:gitea;GIT.example.com:gitea",
+			`"git.example.com" is listed twice`,
+		},
+		{"git.example.com:gitea,gitea", `"gitea" is listed twice`},
+		{"git.example.com:gitea,", `"gitea," has an empty item in its list`},
+	} {
+		t.Run(tc.value, func(t *testing.T) {
+			t.Parallel()
+
+			_, err := config.FromEnvironment(environment{apps: tc.value}.lookupEnv)
+
+			want := apps + ": " + tc.want
+			if err == nil || err.Error() != want {
+				t.Errorf("error %v, want %s", err, want)
+			}
+		})
+	}
+}
+
 func TestWAFBodyLimitOf64K(t *testing.T) {
 	t.Parallel()
 
@@ -2589,6 +2684,7 @@ func TestLogsEachSettingWithItsValue(t *testing.T) {
 		wafExemptPaths:       "",
 		wafBodyLimit:         off,
 		exclusionsFile:       "",
+		apps:                 "", // logged as null, which decodes as ""
 		trapPaths:            "",
 		errorBurstThreshold:  "30",
 		logRemoteURL:         "",

internal/coreruleset/coreruleset.go

@@ -1,9 +1,9 @@
 // Package coreruleset runs the OWASP Core Rule Set 4.25.0, through Coraza, on the
 // method, the URL with its query and the headers of a request, and on its
-// body while SWW_WAF_BODY_LIMIT is set, with the eleven changes sww
+// body while SWW_WAF_BODY_LIMIT is set, with the six changes sww
-// makes to it and the exclusions in SWW_CORE_RULE_SET_EXCLUSIONS_FILE, as
+// makes to it, the fixes for the apps SWW_APPS names, and the exclusions in
-// "Attack detection" under "Settings" in SPEC.md describes them. It reads no
+// SWW_CORE_RULE_SET_EXCLUSIONS_FILE, as "Attack detection" under "Settings"
-// response.
+// in SPEC.md describes them. It reads no response.
 //
 // sww writes only to its state directory, so Coraza is built with
 // its no_fs_access tag, as the Dockerfile and script/build build it: of a
@@ -16,6 +16,8 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"maps"
+	"net"
 	"net/http"
 	"net/netip"
 	"os"
@@ -32,9 +34,8 @@ import (
 
 // directives are the Core Rule Set as sww runs it, with the
 // paranoia level for %d, bodyDirectives for the first %s while
-// SWW_WAF_BODY_LIMIT is set, the exclusions file for the second,
+// SWW_WAF_BODY_LIMIT is set, the exclusions file for the second, and the
-// giteaExclusions for the third, wordpressExclusions for the fourth,
+// directives of every app in apps for the third.
-// drupalExclusions for the fifth, and mediawikiExclusions for the sixth.
 // Each rule sww adds has an id from 900000 to 900999, the ids the
 // Core Rule Set keeps for the rules that set it up, which
 // SWW_WAF_DISABLED_RULES and the exclusions file refuse, so that no
@@ -82,53 +83,28 @@ SecRule ARGUMENTS_LIMIT_REACHED "@eq 1" "id:900300,phase:2,pass,\
 # before the rules of phase 1 too.
 %s
 
-# The eighth change comes before the rules for the same reason.
+# The apps' fixes come before the rules for the same reason.
 %s
 
-# The ninth change comes before the rules for the same reason.
+# The fifth: only the rules for requests are loaded, and no response is
-%s
-
-# So does the tenth.
-%s
-
-# And the eleventh.
-%s
-
-# The sixth: only the rules for requests are loaded, and no response is
 # inspected.
 Include @owasp_crs/REQUEST-*.conf
 
 # The third: redirect_uri is not checked for a URL naming an IP address or
-# localhost. Coraza matches a parameter name here, and in the fourth,
+# localhost. Coraza matches a parameter name here without regard to case.
-# without regard to case. ARGS holds the fields of a form data or multipart
+# ARGS holds the fields of a form data or multipart body Coraza reads as
-# body Coraza reads as well as the query parameters, so a field of one of
+# well as the query parameters, so a field of this name is left out too.
-# these names is left out too.
 SecRuleUpdateTargetById 931100 "!ARGS:redirect_uri"
 SecRuleUpdateTargetById 934110 "!ARGS:redirect_uri"
 
-# The fourth: the query parameters in which gitea sends names within a
+# The fourth: Referer is not checked for a Unix command without arguments,
-# repository or its own records, or a page of its own site, are not
+# for Java starting a process, or for a Java class name. 944130 refused
-# checked against the lists of system files, shell paths and command
+# every page opened from the page of java.lang.String.md.
-# names. Coraza takes one rule id per directive.
-SecRuleUpdateTargetById 930120 "!ARGS:path|!ARGS:files|!ARGS:skip-to|\
-    !ARGS:sub_path|!ARGS:ref|!ARGS:sha|!ARGS:branch|!ARGS:workflow|\
-    !ARGS:artifactName|!ARGS:redirect_to"
-SecRuleUpdateTargetById 932160 "!ARGS:path|!ARGS:files|!ARGS:skip-to|\
-    !ARGS:sub_path|!ARGS:ref|!ARGS:sha|!ARGS:branch|!ARGS:workflow|\
-    !ARGS:artifactName|!ARGS:redirect_to"
-SecRuleUpdateTargetById 932260 "!ARGS:path|!ARGS:files|!ARGS:skip-to|\
-    !ARGS:sub_path|!ARGS:ref|!ARGS:sha|!ARGS:branch|!ARGS:workflow|\
-    !ARGS:artifactName|!ARGS:redirect_to"
-
-# The fifth, for Referer: it is not checked for a Unix command without
-# arguments, for Java starting a process, or for a Java class name. 944130
-# refused every page opened from the page of java.lang.String.md. The
-# cookies are left out in Inspect.
 SecRuleUpdateTargetById 932340 "!REQUEST_HEADERS:Referer"
 SecRuleUpdateTargetById 944110 "!REQUEST_HEADERS:Referer"
 SecRuleUpdateTargetById 944130 "!REQUEST_HEADERS:Referer"
 
-# The seventh: a container image push that reuses a layer names the image
+# The sixth: a container image push that reuses a layer names the image
 # it takes the layer from in the query parameter from, which is not
 # checked for command names. 932260 refused the push of a layer from
 # owner/python3-app.
@@ -178,39 +154,49 @@ SecRule MULTIPART_STRICT_ERROR "!@eq 0" "id:900450,phase:2,pass,\
     severity:'CRITICAL',setvar:'tx.inbound_anomaly_score_pl1=+5'"
 `
 
-// giteaExclusions are the eighth change: the fields of gitea's own
+// app is an app whose ordinary requests the Core Rule Set would refuse,
-// requests that skip the rules that refused them there, as Coraza
+// with the fixes that let them pass.
-// directives.
+type app struct {
-//
+	// directives are Coraza exclusions, loaded before the Core Rule Set's
+	// rules. Their first rule skips to the marker they end with, unless
+	// Inspect sets the transaction variable named for the app, such as
+	// app_gitea. The skip reaches only phase 1, so a rule of a later phase
+	// must check that variable itself.
+	directives string
+	// cookies are the cookies the Core Rule Set reads a request without.
+	cookies []string
+}
+
 //go:embed gitea.conf
-var giteaExclusions string
+var giteaDirectives string
 
-// wordpressExclusions are the ninth change: the fields of WordPress's own
-// requests that skip the rules that refused them there, as Coraza
-// directives.
-//
 //go:embed wordpress.conf
-var wordpressExclusions string
+var wordpressDirectives string
 
-// drupalExclusions are the tenth change: the fields of Drupal's own
-// requests that skip the rules that refused them there, as Coraza
-// directives.
-//
 //go:embed drupal.conf
-var drupalExclusions string
+var drupalDirectives string
 
-// mediawikiExclusions are the eleventh change: the fields of MediaWiki's
-// own requests that skip the rules that refused them there, as Coraza
-// directives.
-//
 //go:embed mediawiki.conf
-var mediawikiExclusions string
+var mediawikiDirectives string
 
-// cookiesNotRead are the cookies the Core Rule Set reads a request
+// apps are the apps whose fixes sww has, by the name SWW_APPS gives each.
-// without, the rest of the fifth change.
 //
-//nolint:gochecknoglobals // a constant cannot be a list
+//nolint:gochecknoglobals // a constant cannot be a map
-var cookiesNotRead = []string{"gitea_flash", "redirect_to"}
+var apps = map[string]app{
+	"drupal": {directives: drupalDirectives},
+	"gitea": {
+		directives: giteaDirectives,
+		cookies:    []string{"gitea_flash", "redirect_to"},
+	},
+	"mediawiki": {directives: mediawikiDirectives},
+	"wordpress": {directives: wordpressDirectives},
+}
+
+// AppNames returns the names of the apps whose fixes sww has, in
+// alphabetical order.
+func AppNames() []string {
+	return slices.Sorted(maps.Keys(apps))
+}
 
 // Params are what New needs.
 type Params struct {
@@ -226,6 +212,10 @@ type Params struct {
 	// Core Rule Set's rules (SWW_CORE_RULE_SET_EXCLUSIONS_FILE), "" while
 	// there is none.
 	ExclusionsFile string
+	// Apps are the names of the apps each hostname serves, by hostname in
+	// lowercase (SWW_APPS). A request gets the fixes of its hostname's
+	// apps only, or of every app while Apps is nil.
+	Apps map[string][]string
 }
 
 // The ids of sww's own rules, which an exclusions file may not
@@ -317,13 +307,15 @@ func checkExclusions(exclusions string) error {
 type CoreRuleSet struct {
 	engine    coraza.WAF
 	bodyLimit int64
+	apps      map[string][]string
 }
 
-// New returns the Core Rule Set with the eleven changes, at params'
+// New returns the Core Rule Set with the six changes and the apps' fixes,
-// paranoia level, without the rules it switches off, reading request
+// at params' paranoia level, without the rules it switches off, reading
-// bodies up to params' limit, and with params' exclusions file loaded
+// request bodies up to params' limit, and with params' exclusions file
-// before the Core Rule Set's rules. An exclusions file is an error if it
+// loaded before the Core Rule Set's rules. An exclusions file is an error
-// cannot be read or does not parse, or if checkExclusions refuses it.
+// if it cannot be read or does not parse, or if checkExclusions refuses
+// it.
 func New(params Params) (*CoreRuleSet, error) {
 	body := ""
 	if params.BodyLimit > 0 {
@@ -346,9 +338,13 @@ func New(params Params) (*CoreRuleSet, error) {
 		}
 	}
 
+	var fixes strings.Builder
+	for _, name := range AppNames() {
+		fixes.WriteString(apps[name].directives + "\n")
+	}
+
 	text := fmt.Sprintf(directives, params.ParanoiaLevel, body, exclusions,
-		giteaExclusions, wordpressExclusions, drupalExclusions,
+		fixes.String())
-		mediawikiExclusions)
 
 	if len(params.DisabledRules) > 0 {
 		ids := make([]string, len(params.DisabledRules))
@@ -366,7 +362,9 @@ func New(params Params) (*CoreRuleSet, error) {
 		return nil, fmt.Errorf("load the Core Rule Set: %w", err)
 	}
 
-	return &CoreRuleSet{engine: engine, bodyLimit: params.BodyLimit}, nil
+	return &CoreRuleSet{
+		engine: engine, bodyLimit: params.BodyLimit, apps: params.Apps,
+	}, nil
 }
 
 // Result is what the Core Rule Set found in a request.
@@ -378,11 +376,12 @@ type Result struct {
 	Score int
 }
 
-// Inspect runs the Core Rule Set on r, a request from client: on its
+// Inspect runs the Core Rule Set on r, a request from client, with the
-// method, its URL with the query, and its headers, the Cookie header
+// fixes of the apps appsFor names for r's hostname: on its method, its URL
-// without the cookies in cookiesNotRead, and on body, r's body as the
+// with the query, and its headers, the Cookie header without those apps'
-// caller has it, as readBody reads it. It returns what it found, what it
+// cookies, and on body, r's body as the caller has it, as readBody reads
-// read of body, and the error that ended the reading early, if one did.
+// it. It returns what it found, what it read of body, and the error that
+// ended the reading early, if one did.
 func (c *CoreRuleSet) Inspect(
 	r *http.Request, client netip.Addr, body io.Reader,
 ) (Result, []byte, error) {
@@ -390,13 +389,24 @@ func (c *CoreRuleSet) Inspect(
 	// Closing would remove the files Coraza wrote, and it writes none.
 	defer func() { _ = tx.Close() }()
 
+	// The transaction's variables are set only through Coraza's interface
+	// for plugins.
+	state := tx.(plugintypes.TransactionState) //nolint:forcetypeassert // every one is
+
+	var cookiesNotRead []string
+
+	for _, name := range c.appsFor(r.Host) {
+		state.Variables().TX().Set("app_"+name, []string{"1"})
+		cookiesNotRead = append(cookiesNotRead, apps[name].cookies...)
+	}
+
 	tx.ProcessConnection(client.String(), 0, "", 0)
 	tx.ProcessURI(r.URL.String(), r.Method, r.Proto)
 
 	for name, values := range r.Header {
 		for _, value := range values {
 			if name == "Cookie" {
-				value = withoutCookiesNotRead(value)
+				value = withoutCookies(value, cookiesNotRead)
 				if value == "" {
 					continue // it held those cookies alone
 				}
@@ -489,9 +499,26 @@ func score(tx types.Transaction) int {
 	return n
 }
 
-// withoutCookiesNotRead returns value, a Cookie header's, without the
+// appsFor returns the names of the apps whose fixes a request for host,
-// cookies in cookiesNotRead.
+// its Host header, gets: every app while SWW_APPS is unset, and otherwise
-func withoutCookiesNotRead(value string) string {
+// those SWW_APPS lists for host's name, without the port and in
+// lowercase.
+func (c *CoreRuleSet) appsFor(host string) []string {
+	if c.apps == nil {
+		return AppNames()
+	}
+
+	hostname, _, err := net.SplitHostPort(host)
+	if err != nil {
+		hostname = host // it has no port
+	}
+
+	return c.apps[strings.ToLower(hostname)]
+}
+
+// withoutCookies returns value, a Cookie header's, without the cookies
+// named in cookiesNotRead.
+func withoutCookies(value string, cookiesNotRead []string) string {
 	var kept []string
 
 	for cookie := range strings.SplitSeq(value, ";") {

internal/coreruleset/coreruleset_test.go

@@ -36,12 +36,14 @@ var loaded = struct {
 }{loaders: map[string]func() (*coreruleset.CoreRuleSet, error){}}
 
 // loaderFor returns the function that loads the Core Rule Set with params
-// once, making it the first time params are asked for.
+// once, making it the first time params are asked for. %#v writes a nil
+// Apps, which gives every app's fixes, apart from an empty one, which
+// gives none.
 func loaderFor(params coreruleset.Params) func() (*coreruleset.CoreRuleSet, error) {
 	loaded.Lock()
 	defer loaded.Unlock()
 
-	settings := fmt.Sprintf("%+v", params)
+	settings := fmt.Sprintf("%#v", params)
 
 	load, found := loaded.loaders[settings]
 	if !found {
@@ -202,8 +204,8 @@ func atDefaults(t *testing.T) *coreruleset.CoreRuleSet {
 }
 
 // wantChange checks that crs lets through passes, a request one of the
-// eleven changes is for, and still finds result in refused, a request like
+// six changes or an app's fixes are for, and still finds result in
-// it that the change is not for.
+// refused, a request like it that they are not for.
 func wantChange(
 	t *testing.T, crs *coreruleset.CoreRuleSet, passes, refused request,
 	result coreruleset.Result,
@@ -464,6 +466,123 @@ func TestImagePushThatReusesALayerIsNotCheckedForCommandNames(t *testing.T) {
 		matched(930120, 932160))
 }
 
+// giteaFixed are gitea requests that only gitea's fixes let through, one
+// for each kind of fix, each with what the Core Rule Set finds in it
+// without them.
+//
+//nolint:gochecknoglobals // a constant cannot be a list
+var giteaFixed = []struct {
+	request request
+	result  coreruleset.Result
+}{
+	// A search of code, on the path of gitea's search.
+	{get("/explore/code?q=SELECT%20*%20FROM%20users%20WHERE"), matched(942100)},
+	// A file name, in a parameter gitea sends names in, on any path.
+	{get("/?path=.gitignore"), matched(930120)},
+	// A file name, in a cookie of gitea's.
+	{
+		get("/owner/repo", "Cookie: gitea_flash=success%3DFile%2Bpackage.json%2Bdeleted"),
+		matched(930120),
+	},
+}
+
+// The hostnames of the tests of SWW_APPS: the one that serves gitea, and
+// one that serves another app.
+const (
+	giteaHost = "git.example"
+	otherHost = "blog.example"
+)
+
+// gitea is gitea's name in SWW_APPS.
+const gitea = "gitea"
+
+// wordpress is WordPress's name in SWW_APPS.
+const wordpress = "wordpress"
+
+// withHost returns r sent to host.
+func withHost(r request, host string) request {
+	return request{r.method, r.target, append([]string{"Host: " + host}, r.headers...)}
+}
+
+// servingApps returns the Core Rule Set at the defaults, with SWW_APPS
+// giving apps.
+func servingApps(t *testing.T, apps map[string][]string) *coreruleset.CoreRuleSet {
+	t.Helper()
+
+	return shared(t, coreruleset.Params{
+		ParanoiaLevel: 1, DisabledRules: defaultDisabledRules, Apps: apps,
+	})
+}
+
+func TestAppsUnsetGivesEveryHostnameEveryAppsFixes(t *testing.T) {
+	t.Parallel()
+
+	crs := servingApps(t, nil)
+
+	for _, fixed := range giteaFixed {
+		for _, host := range []string{giteaHost, otherHost} {
+			wantResult(t, crs, withHost(fixed.request, host), coreruleset.Result{})
+		}
+	}
+}
+
+func TestListedHostnameGetsItsAppsFixes(t *testing.T) {
+	t.Parallel()
+
+	crs := servingApps(t, map[string][]string{giteaHost: {gitea}})
+
+	// The hostname is matched without the port and without regard to case.
+	for _, host := range []string{giteaHost, "GIT.Example:8443"} {
+		for _, fixed := range giteaFixed {
+			wantResult(t, crs, withHost(fixed.request, host), coreruleset.Result{})
+		}
+	}
+}
+
+func TestUnlistedHostnameGetsTheFullCheck(t *testing.T) {
+	t.Parallel()
+
+	for _, apps := range []map[string][]string{
+		{giteaHost: {gitea}},
+		// SWW_APPS set empty lists no hostname.
+		{},
+	} {
+		crs := servingApps(t, apps)
+
+		for _, host := range []string{otherHost, otherHost + ":8443", "git.example.org"} {
+			for _, fixed := range giteaFixed {
+				wantResult(t, crs, withHost(fixed.request, host), fixed.result)
+			}
+		}
+	}
+}
+
+func TestWordPressFixesApplyOnlyToAHostnameThatServesWordPress(t *testing.T) {
+	t.Parallel()
+
+	crs := servingApps(t, map[string][]string{
+		giteaHost: {gitea}, otherHost: {wordpress},
+	})
+
+	// A search, which only WordPress's fixes let through.
+	search := get("/?s=python3")
+
+	wantResult(t, crs, withHost(search, otherHost), coreruleset.Result{})
+	wantResult(t, crs, withHost(search, giteaHost), matched(932260))
+}
+
+func TestHostnameListingTwoAppsGetsTheFixesOfBoth(t *testing.T) {
+	t.Parallel()
+
+	crs := servingApps(t, map[string][]string{giteaHost: {gitea, wordpress}})
+
+	// A file name that only gitea's fixes let through, and a search that only
+	// WordPress's fixes let through.
+	for _, target := range []string{"/?path=.gitignore", "/?s=python3"} {
+		wantResult(t, crs, withHost(get(target), giteaHost), coreruleset.Result{})
+	}
+}
+
 // withExclusions returns the Core Rule Set at the defaults, with the
 // exclusions file at path.
 func withExclusions(path string) (*coreruleset.CoreRuleSet, error) {
@@ -619,15 +738,16 @@ const (
 var hardValues = []string{"python3", "powershell", "ls%20-la", ".htaccess"}
 
 // wantRecordedRequestsPass checks that none of the recorded ordinary
-// requests in the file name in testdata is refused, at the defaults and
+// requests in the file name in testdata is refused by defaults, which
-// while bodies are read. Each request runs as its own parallel subtest.
+// reads no body, or by bodies, which reads it. Each request runs as its
-func wantRecordedRequestsPass(t *testing.T, name string) {
+// own parallel subtest.
+func wantRecordedRequestsPass(
+	t *testing.T, name string, defaults, bodies *coreruleset.CoreRuleSet,
+) {
 	t.Helper()
 
 	const threshold = 5 // SWW_WAF_ANOMALY_THRESHOLD's default
 
-	defaults, bodies := atDefaults(t), readingBodies(t)
-
 	for _, recorded := range recordedRequests(t, name) {
 		t.Run(recorded.Method+" "+recorded.Target, func(t *testing.T) {
 			t.Parallel()
@@ -810,13 +930,16 @@ func wordpressAttackTargets(attack string) []string {
 	}
 }
 
-func TestOrdinaryWordPressRequestsPassAndAttacksAreRefused(t *testing.T) {
+// wantWordPressRequestsPass checks that the recorded ordinary WordPress
-	t.Parallel()
+// requests pass defaults, which reads no body, and that those with a body
+// pass bodies, which reads it.
+func wantWordPressRequestsPass(
+	t *testing.T, defaults, bodies *coreruleset.CoreRuleSet,
+) {
+	t.Helper()
 
 	const threshold = 5 // SWW_WAF_ANOMALY_THRESHOLD's default
 
-	defaults, bodies := atDefaults(t), readingBodiesUpTo64K(t)
-
 	for _, recorded := range recordedRequests(t, "wordpress-requests.txt") {
 		t.Run(recorded.Method+" "+recorded.Target, func(t *testing.T) {
 			t.Parallel()
@@ -836,6 +959,16 @@ func TestOrdinaryWordPressRequestsPassAndAttacksAreRefused(t *testing.T) {
 			}
 		})
 	}
+}
+
+func TestOrdinaryWordPressRequestsPassAndAttacksAreRefused(t *testing.T) {
+	t.Parallel()
+
+	const threshold = 5 // SWW_WAF_ANOMALY_THRESHOLD's default
+
+	defaults, bodies := atDefaults(t), readingBodiesUpTo64K(t)
+
+	wantWordPressRequestsPass(t, defaults, bodies)
 
 	for _, attack := range []string{
 		sqlInjection,
@@ -912,6 +1045,20 @@ func wordpressWords() []struct {
 	}
 }
 
+func TestHostnameListingWordPressLetsItsRecordedRequestsThrough(t *testing.T) {
+	t.Parallel()
+
+	// The requests were recorded on otherHost.
+	apps := map[string][]string{otherHost: {wordpress}}
+
+	bodies := shared(t, coreruleset.Params{
+		ParanoiaLevel: 1, DisabledRules: defaultDisabledRules, BodyLimit: 64<<10 - 1,
+		Apps: apps,
+	})
+
+	wantWordPressRequestsPass(t, servingApps(t, apps), bodies)
+}
+
 // wordpressBlock is the comment that starts every block of WordPress's
 // HTML, which rule 941180 matches.
 const wordpressBlock = "<!-- wp:paragraph -->"

internal/coreruleset/drupal.conf

@@ -1,4 +1,4 @@
-# The tenth change: on Drupal's paths, some fields skip the rules that refused
+# Drupal's fixes: on Drupal's paths, some fields skip the rules that refused
 # ordinary Drupal requests there. They are the fields where Drupal sends a
 # search, a name, a file name or an address. Each exclusion runs with the
 # request, before the rules it switches off, so this file is loaded before the
@@ -25,6 +25,13 @@
 #   932230: ls -la
 #   932235: python3
 
+# Unless SWW_APPS lists drupal for the request's hostname, every rule below is
+# skipped. Inspect sets tx.app_drupal when it does.
+# The skip reaches only phase 1, so a rule of a later phase must check
+# tx.app_drupal itself.
+SecRule &TX:app_drupal "@eq 0" \
+    "id:900790,phase:1,pass,nolog,skipAfter:END_DRUPAL"
+
 # Every admin page's filters and autocompletes, and the page to return to:
 #   title: /admin/content?title=python3
 #   name: /admin/content/media?name=python3
@@ -237,3 +244,5 @@ SecRule REQUEST_FILENAME "@rx ^(?:/[a-z]{2,3}(?:-[a-z]+)?)?/user/password$" \
     SecRule &ARGS_GET:json.mail "@eq 0" \
         "ctl:ruleRemoveTargetById=932120;ARGS:json.mail,\
         ctl:ruleRemoveTargetById=932260;ARGS:json.mail"
+
+SecMarker END_DRUPAL

internal/coreruleset/drupal_test.go

@@ -5,6 +5,8 @@ import (
 	"net/url"
 	"slices"
 	"testing"
+
+	"sneak.berlin/go/smallwebwaf/internal/coreruleset"
 )
 
 // drupalThreshold is SWW_WAF_ANOMALY_THRESHOLD's default.
@@ -34,7 +36,35 @@ const drupalName = "name="
 func TestOrdinaryDrupalRequestsPass(t *testing.T) {
 	t.Parallel()
 
-	wantRecordedRequestsPass(t, "drupal-requests.txt")
+	wantRecordedRequestsPass(t, "drupal-requests.txt", atDefaults(t), readingBodies(t))
+}
+
+func TestDrupalFixesApplyOnlyToAHostnameThatServesDrupal(t *testing.T) {
+	t.Parallel()
+
+	crs := servingApps(t, map[string][]string{
+		giteaHost: {gitea}, otherHost: {"drupal"},
+	})
+
+	// A search, which only Drupal's fixes let through.
+	search := get("/search?keys=python3")
+
+	wantResult(t, crs, withHost(search, otherHost), coreruleset.Result{})
+	wantResult(t, crs, withHost(search, giteaHost), matched(932260))
+}
+
+func TestHostnameListingDrupalLetsItsRecordedRequestsThrough(t *testing.T) {
+	t.Parallel()
+
+	// The requests were recorded on example.com.
+	apps := map[string][]string{"example.com": {"drupal"}}
+
+	bodies := shared(t, coreruleset.Params{
+		ParanoiaLevel: 1, DisabledRules: defaultDisabledRules, BodyLimit: bodyLimit,
+		Apps: apps,
+	})
+
+	wantRecordedRequestsPass(t, "drupal-requests.txt", servingApps(t, apps), bodies)
 }
 
 // drupalAttacks are an SQL injection, a path traversal and a script

internal/coreruleset/gitea.conf

@@ -1,8 +1,53 @@
-# The eighth change: on gitea's paths, some fields skip the rules that refused
+# gitea's fixes: some fields skip the rules that refused ordinary gitea requests.
-# ordinary gitea requests there. They are the fields where gitea sends a search,
+# They are the fields where gitea sends a search, a file name or a branch name.
-# a file name or a branch name. Each exclusion runs with the request, before the
+# Each exclusion runs with the request, before the rules it switches off, those
-# rules it switches off, those of phase 1 included, so this file is loaded before
+# of phase 1 included, so this file is loaded before the Core Rule Set's rules.
-# the Core Rule Set's rules. Each comment names a request the rule refused.
+# Each comment names a request the rule refused.
+
+# Unless SWW_APPS lists gitea for the request's hostname, every rule below is
+# skipped. Inspect sets tx.app_gitea when it does.
+# The skip reaches only phase 1, so a rule of a later phase must check
+# tx.app_gitea itself.
+SecRule &TX:app_gitea "@eq 0" \
+    "id:900590,phase:1,pass,nolog,skipAfter:END_GITEA"
+
+# The query parameters in which gitea sends names within a repository or its
+# own records, or a page of its own site, are not checked against the lists of
+# system files, shell paths and command names, on any path:
+#   930120: .gitignore
+#   932160: bin/docker-entrypoint
+#   932260: docker-build
+SecAction "id:900591,phase:1,pass,nolog,\
+    ctl:ruleRemoveTargetById=930120;ARGS:path,\
+    ctl:ruleRemoveTargetById=930120;ARGS:files,\
+    ctl:ruleRemoveTargetById=930120;ARGS:skip-to,\
+    ctl:ruleRemoveTargetById=930120;ARGS:sub_path,\
+    ctl:ruleRemoveTargetById=930120;ARGS:ref,\
+    ctl:ruleRemoveTargetById=930120;ARGS:sha,\
+    ctl:ruleRemoveTargetById=930120;ARGS:branch,\
+    ctl:ruleRemoveTargetById=930120;ARGS:workflow,\
+    ctl:ruleRemoveTargetById=930120;ARGS:artifactName,\
+    ctl:ruleRemoveTargetById=930120;ARGS:redirect_to,\
+    ctl:ruleRemoveTargetById=932160;ARGS:path,\
+    ctl:ruleRemoveTargetById=932160;ARGS:files,\
+    ctl:ruleRemoveTargetById=932160;ARGS:skip-to,\
+    ctl:ruleRemoveTargetById=932160;ARGS:sub_path,\
+    ctl:ruleRemoveTargetById=932160;ARGS:ref,\
+    ctl:ruleRemoveTargetById=932160;ARGS:sha,\
+    ctl:ruleRemoveTargetById=932160;ARGS:branch,\
+    ctl:ruleRemoveTargetById=932160;ARGS:workflow,\
+    ctl:ruleRemoveTargetById=932160;ARGS:artifactName,\
+    ctl:ruleRemoveTargetById=932160;ARGS:redirect_to,\
+    ctl:ruleRemoveTargetById=932260;ARGS:path,\
+    ctl:ruleRemoveTargetById=932260;ARGS:files,\
+    ctl:ruleRemoveTargetById=932260;ARGS:skip-to,\
+    ctl:ruleRemoveTargetById=932260;ARGS:sub_path,\
+    ctl:ruleRemoveTargetById=932260;ARGS:ref,\
+    ctl:ruleRemoveTargetById=932260;ARGS:sha,\
+    ctl:ruleRemoveTargetById=932260;ARGS:branch,\
+    ctl:ruleRemoveTargetById=932260;ARGS:workflow,\
+    ctl:ruleRemoveTargetById=932260;ARGS:artifactName,\
+    ctl:ruleRemoveTargetById=932260;ARGS:redirect_to"
 
 # gitea's searches of code, of issues and pull requests, and of commits send the
 # text searched for in q, which skips these rules there:
@@ -160,8 +205,8 @@ SecRule REQUEST_FILENAME \
 #   942140: information_schema.sql
 #   944110: java/lang/Runtime.java
 #   944130: java.lang.String.md
-# Each request skips the rules that refused it. The fourth change already has
+# Each request skips the rules that refused it. Rule 900591 already has path and
-# path and redirect_to skip 930120, 932160 and 932260 on every path.
+# redirect_to skip 930120, 932160 and 932260 on every path.
 
 # A file's commit graph, in file.
 SecRule REQUEST_FILENAME "@rx ^/[^/]+/[^/]+/graph$" \
@@ -286,3 +331,5 @@ SecRule REQUEST_FILENAME \
     "@rx ^/api/actions_pipeline/_apis/pipelines/workflows/[0-9]+/artifacts/[^/]+/upload$" \
     "id:900640,phase:1,pass,nolog,\
     ctl:ruleRemoveTargetById=920450;REQUEST_HEADERS_NAMES:Content-Range"
+
+SecMarker END_GITEA

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

internal/coreruleset/mediawiki_test.go

@@ -4,11 +4,16 @@ import (
 	"net/http"
 	"slices"
 	"testing"
+
+	"sneak.berlin/go/smallwebwaf/internal/coreruleset"
 )
 
 // mediawikiThreshold is SWW_WAF_ANOMALY_THRESHOLD's default.
 const mediawikiThreshold = 5
 
+// mediawiki is MediaWiki's name in SWW_APPS.
+const mediawiki = "mediawiki"
+
 // mediawikiEdit is the address MediaWiki's edit form posts to.
 const mediawikiEdit = "/index.php?title=Example&action=submit"
 
@@ -45,7 +50,58 @@ const (
 func TestOrdinaryMediaWikiRequestsPass(t *testing.T) {
 	t.Parallel()
 
-	wantRecordedRequestsPass(t, "mediawiki-requests.txt")
+	wantRecordedRequestsPass(t, "mediawiki-requests.txt", atDefaults(t), readingBodies(t))
+}
+
+func TestMediaWikiFixesApplyOnlyToAHostnameThatServesMediaWiki(t *testing.T) {
+	t.Parallel()
+
+	crs := servingApps(t, map[string][]string{
+		giteaHost: {gitea}, otherHost: {mediawiki},
+	})
+
+	// A search, which only MediaWiki's fixes let through.
+	search := get("/index.php?title=Special:Search&search=python3")
+
+	wantResult(t, crs, withHost(search, otherHost), coreruleset.Result{})
+	wantResult(t, crs, withHost(search, giteaHost), matched(932260))
+}
+
+func TestMediaWikiWatchlistFixAppliesOnlyToAHostnameThatServesMediaWiki(t *testing.T) {
+	t.Parallel()
+
+	crs := shared(t, coreruleset.Params{
+		ParanoiaLevel: 1, DisabledRules: defaultDisabledRules, BodyLimit: bodyLimit,
+		Apps: map[string][]string{giteaHost: {gitea}, otherHost: {mediawiki}},
+	})
+
+	// A watchlist that only the phase 2 rule 900916 lets through.
+	r := request{http.MethodPost, mediawikiWatchlist.target, []string{formData}}
+	body := mediawikiWatchlist.field + "Lighthouse%20notes%0D%0APython3%20notes"
+
+	got, _ := inspectBody(t, crs, withHost(r, otherHost), body)
+	if got.Score >= mediawikiThreshold {
+		t.Errorf("POST %s %s on %s refused: %+v", r.target, body, otherHost, got)
+	}
+
+	got, _ = inspectBody(t, crs, withHost(r, giteaHost), body)
+	if got.Score < mediawikiThreshold {
+		t.Errorf("POST %s %s on %s let through: %+v", r.target, body, giteaHost, got)
+	}
+}
+
+func TestHostnameListingMediaWikiLetsItsRecordedRequestsThrough(t *testing.T) {
+	t.Parallel()
+
+	// The requests were recorded on example.com.
+	apps := map[string][]string{"example.com": {mediawiki}}
+
+	bodies := shared(t, coreruleset.Params{
+		ParanoiaLevel: 1, DisabledRules: defaultDisabledRules, BodyLimit: bodyLimit,
+		Apps: apps,
+	})
+
+	wantRecordedRequestsPass(t, "mediawiki-requests.txt", servingApps(t, apps), bodies)
 }
 
 // mediawikiQueryFields and mediawikiBodyFields together hold every field that

internal/coreruleset/wordpress.conf

@@ -1,10 +1,17 @@
-# The ninth change: on WordPress's paths, some fields skip the rules that refused
+# WordPress's fixes: on WordPress's paths, some fields skip the rules that refused
 # ordinary WordPress requests there. Each exclusion runs with the request, before
 # the rules it switches off, so this file is loaded before the Core Rule Set's
 # rules. Each comment names a request the rule refused. An exclusion on a field
 # of a body applies only when the query has no parameter of that name, so it
 # matters only while SWW_WAF_BODY_LIMIT is set.
 
+# Unless SWW_APPS lists wordpress for the request's hostname, every rule below is
+# skipped. Inspect sets tx.app_wordpress when it does.
+# The skip reaches only phase 1, so a rule of a later phase must check
+# tx.app_wordpress itself.
+SecRule &TX:app_wordpress "@eq 0" \
+    "id:900690,phase:1,pass,nolog,skipAfter:END_WORDPRESS"
+
 # WordPress takes a call to its REST API at any of four addresses:
 #   /wp-json/wp/v2/posts/1
 #   /index.php/wp-json/wp/v2/posts/1
@@ -195,3 +202,5 @@ SecRule REQUEST_FILENAME "@rx ^/(?:(?:index\.php/)?page/[0-9]+/?|index\.php)?$"
 # so skips 932340 there.
 SecRule REQUEST_FILENAME "@streq /wp-admin/upload.php" \
     "id:900711,phase:1,pass,nolog,ctl:ruleRemoveTargetById=932340;ARGS:_wp_http_referer"
+
+SecMarker END_WORDPRESS

internal/discriminator/coreruleset_test.go

@@ -10,6 +10,7 @@ import (
 	"testing"
 
 	"sneak.berlin/go/smallwebwaf/internal/alerts"
+	"sneak.berlin/go/smallwebwaf/internal/discriminator"
 	"sneak.berlin/go/smallwebwaf/internal/ratelimit"
 	"sneak.berlin/go/smallwebwaf/internal/requestlog"
 )
@@ -21,6 +22,7 @@ const (
 	wafDisabledRules    = "SWW_WAF_DISABLED_RULES"
 	wafExemptPaths      = "SWW_WAF_EXEMPT_PATHS"
 	wafBodyLimit        = "SWW_WAF_BODY_LIMIT"
+	apps                = "SWW_APPS"
 	block               = "block"
 	detect              = "detect"
 )
@@ -290,6 +292,27 @@ func TestDisabledRulesSwitchOffWhatGiteaWouldBeRefused(t *testing.T) {
 	}
 }
 
+func TestGiteasFixesApplyOnlyToAHostnameThatServesGitea(t *testing.T) {
+	t.Parallel()
+
+	// Only gitea's fixes let a file name through in path, a parameter
+	// gitea sends file names in.
+	const fileName = "/?path=.gitignore"
+
+	s := startDiscriminator(t, "", map[string]string{
+		wafMode: block, apps: siteA + ":gitea",
+	})
+
+	wantDisposition(t, do(t, s.question(siteA, client, fileName)),
+		http.StatusOK, discriminator.DispositionAllow)
+	wantDisposition(t, do(t, s.question(siteB, client, fileName)),
+		http.StatusForbidden, discriminator.DispositionDeny)
+
+	lines := s.out.requestLines(t, 2)
+	wantLine(t, lines[0], http.StatusOK, requestlog.ActionForward)
+	wantLine(t, lines[1], http.StatusForbidden, requestlog.ActionBlockedByCoreRuleSet)
+}
+
 func TestAttackInAFormBodyIsRefusedOnlyWhileBodiesAreRead(t *testing.T) {
 	t.Parallel()
 

internal/discriminator/proxy.go

@@ -221,7 +221,8 @@ func newReputation(
 // NewCoreRuleSet returns the Core Rule Set at SWW_WAF_PARANOIA_LEVEL,
 // without the rules SWW_WAF_DISABLED_RULES switches off, reading bodies
 // up to SWW_WAF_BODY_LIMIT, with the exclusions in
-// SWW_CORE_RULE_SET_EXCLUSIONS_FILE, or nil while SWW_WAF_MODE is off. It
+// SWW_CORE_RULE_SET_EXCLUSIONS_FILE and the fixes of the apps in SWW_APPS,
+// or nil while SWW_WAF_MODE is off. It
 // reads at most QuestionBodyMaxBytes less one byte: a question's body of
 // QuestionBodyMaxBytes may be cut short, and the Core Rule Set does not read a
 // JSON or XML body over its limit. An exclusions file that coreruleset.New refuses is
@@ -236,6 +237,7 @@ func NewCoreRuleSet(cfg *config.Config) (*coreruleset.CoreRuleSet, error) {
 		ParanoiaLevel: cfg.WAFParanoiaLevel, DisabledRules: cfg.WAFDisabledRules,
 		BodyLimit:      min(cfg.WAFBodyLimit, QuestionBodyMaxBytes-1),
 		ExclusionsFile: cfg.CoreRuleSetExclusionsFile,
+		Apps:           cfg.Apps,
 	})
 	if err != nil {
 		return nil, fmt.Errorf("SWW_CORE_RULE_SET_EXCLUSIONS_FILE: %w", err)