nixos/nextcloud: fixup openssl compat change

Upon testing the change itself I realized that it doesn't build properly
because

* the `pname` of a php extension is `php-<name>`, not `<name>`.
* calling the extension `openssl-legacy` resulted in PHP trying to compile
`ext/openssl-legacy` which broke since it doesn't exist:

source root is php-8.1.12
setting SOURCE_DATE_EPOCH to timestamp 1666719000 of file php-8.1.12/win32/wsyslog.c
patching sources
cdToExtensionRootPhase
/nix/store/48mnkga4kh84xyiqwzx8v7iv090i7z66-stdenv-linux/setup: line 1399: cd: ext/openssl-legacy: No such file or directory

I didn't encounter that one before because I was mostly interested in
having a sane behavior for everyone not using this "feature" and the
documentation around this. My findings about the behavior with turning
openssl1.1 on/off are still valid because I tested this on `master` with
manually replacing `openssl` by `openssl_1_1` in `php-packages.nix`.

To work around the issue I had to slightly modify the extension
build-system for PHP:

* The attribute `extensionName` is now relevant to determine the output
paths (e.g. `lib/openssl.so`). This is not a behavioral change for
existing extensions because then `extensionName==name`.

However when specifying `extName` in `php-packages.nix` this value is
overridden and it is made sure that the extension called `extName` NOT
`name` (i.e. `openssl` vs `openssl-legacy`) is built and installed.

The `name` still has to be kept to keep the legacy openssl available
as `php.extensions.openssl-legacy`.

Additionally I implemented a small VM test to check the behavior with
server-side encryption:

* For `stateVersion` below 22.11, OpenSSL 1.1 is used (in `basic.nix`
it's checked that OpenSSL 3 is used). With that the "default"
behavior of the module is checked.

* It is ensured that the PHP interpreter for Nextcloud's php-fpm
actually loads the correct openssl extension.

* It is tested that (encrypted) files remain usable when (temporarily)
installing OpenSSL3 (of course then they're not decryptable, but on a
rollback that should still be possible).

Finally, a few more documentation changes:

* I also mentioned the issue in `nextcloud.xml` to make sure the issue
is at least mentioned in the manual section about Nextcloud. Not too
much detail here, but the relevant option `enableBrokenCiphersForSSE`
is referenced.

* I fixed a few minor wording issues to also give the full context
(we're talking about Nextcloud; we're talking about the PHP extension
**only**; please check if you really need this even though it's
enabled by default).

This is because I felt that sometimes it might be hard to understand
what's going on when e.g. an eval-warning appears without telling where
exactly it comes from.

nixos/doc/manual/from_md/release-notes/rl-2211.section.xml

···
       <listitem>
         <para>
           The <literal>openssl</literal>-extension for the PHP
-          interpreter used by <literal>services.nextcloud</literal> is
-          built against OpenSSL 1.1 if
+          interpreter used by Nextcloud is built against OpenSSL 1.1 if
           <xref linkend="opt-system.stateVersion" /> is below
           <literal>22.11</literal>. This is to make sure that people
           using

nixos/doc/manual/release-notes/rl-2211.section.md

···
 
 - The `p4` package now only includes the open-source Perforce Helix Core command-line client and APIs. It no longer installs the unfree Helix Core Server binaries `p4d`, `p4broker`, and `p4p`. To install the Helix Core Server binaries, use the `p4d` package instead.
 
-- The `openssl`-extension for the PHP interpreter used by `services.nextcloud` is built against OpenSSL 1.1 if
+- The `openssl`-extension for the PHP interpreter used by Nextcloud is built against OpenSSL 1.1 if
   [](#opt-system.stateVersion) is below `22.11`. This is to make sure that people using [server-side encryption](https://docs.nextcloud.com/server/latest/admin_manual/configuration_files/encryption_configuration.html)
   don't loose access to their files.
 

nixos/modules/services/web-apps/nextcloud.nix

···
     extensions = { enabled, all }:
       (with all;
         # disable default openssl extension
-        (lib.filter (e: e.pname != "openssl") enabled)
+        (lib.filter (e: e.pname != "php-openssl") enabled)
         # use OpenSSL 1.1 for RC4 Nextcloud encryption if user
         # has acknowledged the brokeness of the ciphers (RC4).
         # TODO: remove when https://github.com/nextcloud/server/issues/32003 is fixed.
···
       default = versionOlder stateVersion "22.11";
       defaultText = literalExpression "versionOlder system.stateVersion \"22.11\"";
       description = lib.mdDoc ''
-        This option uses OpenSSL PHP extension linked against OpenSSL 1.1 rather
-        than latest OpenSSL (≥ 3), this is not recommended except if you need
-        it.
-
-        Server-side encryption in Nextcloud uses RC4 ciphers, a broken cipher
-        since ~2004.
+        This option enables using the OpenSSL PHP extension linked against OpenSSL 1.1
+        rather than latest OpenSSL (≥ 3), this is not recommended unless you need
+        it for server-side encryption (SSE). SSE uses the legacy RC4 cipher which is
+        considered broken for several years now. See also [RFC7465](https://datatracker.ietf.org/doc/html/rfc7465).
 
         This cipher has been disabled in OpenSSL ≥ 3 and requires
         a specific legacy profile to re-enable it.
 
-        If you upgrade to a Nextcloud using OpenSSL ≥ 3 and have
+        If you deploy Nextcloud using OpenSSL ≥ 3 for PHP and have
         server-side encryption configured, you will not be able to access
         your files anymore. Enabling this option can restore access to your files.
         Upon testing we didn't encounter any data corruption when turning
         this on and off again, but this cannot be guaranteed for
         each Nextcloud installation.
 
-        Unless you are using external storage,
-        it is advised to [disable server-side encryption](https://docs.nextcloud.com/server/latest/admin_manual/configuration_files/encryption_configuration.html#disabling-encryption) as it is unclear
-        it provides any amount of security beyond encryption for external storage.
+        It is `true` by default for systems with a [](#opt-system.stateVersion) below
+        `22.11` to make sure that existing installations won't break on update. On newer
+        NixOS systems you have to explicitly enable it on your own.
+
+        Please note that this only provides additional value when using
+        external storage such as S3 since it's not an end-to-end encryption.
+        If this is not the case,
+        it is advised to [disable server-side encryption](https://docs.nextcloud.com/server/latest/admin_manual/configuration_files/encryption_configuration.html#disabling-encryption) and set this to `false`.
 
         In the future, Nextcloud may move to AES-256-GCM, by then,
         this option will be removed.
···
           This is only necessary if you're using Nextcloud's server-side encryption.
           Please keep in mind that it's using the broken RC4 cipher.
 
-          If you don't use that feature, you can switch to OpenSSL 3 by declaring
+          If you don't use that feature, you can switch to OpenSSL 3 and get
+          rid of this warning by declaring
 
             services.nextcloud.enableBrokenCiphersForSSE = false;
 
+          If you need to use server-side encryption you can ignore this waring.
           Otherwise you'd have to disable server-side encryption first in order
-          to be able to safely disable this option and get rid of that warning.
+          to be able to safely disable this option and get rid of this warning.
           See <https://docs.nextcloud.com/server/latest/admin_manual/configuration_files/encryption_configuration.html#disabling-encryption> on how to achieve this.
 
           For more context, here is the implementing pull request: https://github.com/NixOS/nixpkgs/pull/198470

nixos/modules/services/web-apps/nextcloud.xml

···
      </listitem>
     </itemizedlist>
    </listitem>
+   <listitem>
+    <formalpara>
+     <title>Server-side encryption</title>
+     <para>
+      Nextcloud supports <link xlink:href="https://docs.nextcloud.com/server/latest/admin_manual/configuration_files/encryption_configuration.html">server-side encryption (SSE)</link>.
+      This is not an end-to-end encryption, but can be used to encrypt files that will be persisted
+      to external storage such as S3. Please note that this won't work anymore when using OpenSSL 3
+      for PHP's openssl extension because this is implemented using the legacy cipher RC4.
+      If <xref linkend="opt-system.stateVersion" /> is <emphasis>above</emphasis> <literal>22.05</literal>,
+      this is disabled by default. To turn it on again and for further information please refer to
+      <xref linkend="opt-services.nextcloud.enableBrokenCiphersForSSE" />.
+     </para>
+    </formalpara>
+   </listitem>
   </itemizedlist>
  </section>
 

nixos/tests/nextcloud/basic.nix

···
         "d /var/lib/nextcloud-data 0750 nextcloud nginx - -"
       ];
 
-      system.stateVersion = "22.11";
+      system.stateVersion = "22.11"; # stateVersion >=21.11 to make sure that we use OpenSSL3
 
       services.nextcloud = {
         enable = true;
         datadir = "/var/lib/nextcloud-data";
         hostName = "nextcloud";
-        enableBrokenCiphersForSSE = args.enableBrokenCiphersForSSE or false;
         config = {
           # Don't inherit adminuser since "root" is supposed to be the default
           adminpassFile = "${pkgs.writeText "adminpass" adminpass}"; # Don't try this at home!
···
     # This is just to ensure the nextcloud-occ program is working
     nextcloud.succeed("nextcloud-occ status")
     nextcloud.succeed("curl -sSf http://nextcloud/login")
+    # Ensure that no OpenSSL 1.1 is used.
+    nextcloud.succeed(
+        "${nodes.nextcloud.services.phpfpm.pools.nextcloud.phpPackage}/bin/php -i | grep 'OpenSSL Library Version' | awk -F'=>' '{ print $2 }' | awk '{ print $2 }' | grep -v 1.1"
+    )
     nextcloud.succeed(
         "${withRcloneEnv} ${copySharedFile}"
     )
···
         "${withRcloneEnv} ${diffSharedFile}"
     )
     assert "hi" in client.succeed("cat /mnt/dav/test-shared-file")
+    nextcloud.succeed("grep -vE '^HBEGIN:oc_encryption_module' /var/lib/nextcloud-data/data/root/files/test-shared-file")
   '';
 })) args

nixos/tests/nextcloud/default.nix

···
 foldl
   (matrix: ver: matrix // {
     "basic${toString ver}" = import ./basic.nix { inherit system pkgs; nextcloudVersion = ver; };
-    "with-legacy-openssl${toString ver}" = import ./basic.nix {
+    "openssl-sse${toString ver}" = import ./openssl-sse.nix {
       inherit system pkgs;
       nextcloudVersion = ver;
-      enableBrokenCiphersForSSE = true;
     };
     "with-postgresql-and-redis${toString ver}" = import ./with-postgresql-and-redis.nix {
       inherit system pkgs;

nixos/tests/nextcloud/openssl-sse.nix

···
+args@{ pkgs, nextcloudVersion ? 25, ... }:
+
+(import ../make-test-python.nix ({ pkgs, ...}: let
+  adminuser = "root";
+  adminpass = "notproduction";
+  nextcloudBase = {
+    networking.firewall.allowedTCPPorts = [ 80 ];
+    system.stateVersion = "22.05"; # stateVersions <22.11 use openssl 1.1 by default
+    services.nextcloud = {
+      enable = true;
+      config.adminpassFile = "${pkgs.writeText "adminpass" adminpass}";
+      package = pkgs.${"nextcloud" + (toString nextcloudVersion)};
+    };
+  };
+in {
+  name = "nextcloud-openssl";
+  meta = with pkgs.lib.maintainers; {
+    maintainers = [ ma27 ];
+  };
+  nodes.nextcloudwithopenssl1 = {
+    imports = [ nextcloudBase ];
+    services.nextcloud.hostName = "nextcloudwithopenssl1";
+  };
+  nodes.nextcloudwithopenssl3 = {
+    imports = [ nextcloudBase ];
+    services.nextcloud = {
+      hostName = "nextcloudwithopenssl3";
+      enableBrokenCiphersForSSE = false;
+    };
+  };
+  testScript = { nodes, ... }: let
+    withRcloneEnv = host: pkgs.writeScript "with-rclone-env" ''
+      #!${pkgs.runtimeShell}
+      export RCLONE_CONFIG_NEXTCLOUD_TYPE=webdav
+      export RCLONE_CONFIG_NEXTCLOUD_URL="http://${host}/remote.php/webdav/"
+      export RCLONE_CONFIG_NEXTCLOUD_VENDOR="nextcloud"
+      export RCLONE_CONFIG_NEXTCLOUD_USER="${adminuser}"
+      export RCLONE_CONFIG_NEXTCLOUD_PASS="$(${pkgs.rclone}/bin/rclone obscure ${adminpass})"
+      "''${@}"
+    '';
+    withRcloneEnv1 = withRcloneEnv "nextcloudwithopenssl1";
+    withRcloneEnv3 = withRcloneEnv "nextcloudwithopenssl3";
+    copySharedFile1 = pkgs.writeScript "copy-shared-file" ''
+      #!${pkgs.runtimeShell}
+      echo 'hi' | ${withRcloneEnv1} ${pkgs.rclone}/bin/rclone rcat nextcloud:test-shared-file
+    '';
+    copySharedFile3 = pkgs.writeScript "copy-shared-file" ''
+      #!${pkgs.runtimeShell}
+      echo 'bye' | ${withRcloneEnv3} ${pkgs.rclone}/bin/rclone rcat nextcloud:test-shared-file2
+    '';
+    openssl1-node = nodes.nextcloudwithopenssl1.config.system.build.toplevel;
+    openssl3-node = nodes.nextcloudwithopenssl3.config.system.build.toplevel;
+  in ''
+    nextcloudwithopenssl1.start()
+    nextcloudwithopenssl1.wait_for_unit("multi-user.target")
+    nextcloudwithopenssl1.succeed("nextcloud-occ status")
+    nextcloudwithopenssl1.succeed("curl -sSf http://nextcloudwithopenssl1/login")
+
+    with subtest("With OpenSSL 1 SSE can be enabled and used"):
+        nextcloudwithopenssl1.succeed("nextcloud-occ app:enable encryption")
+        nextcloudwithopenssl1.succeed("nextcloud-occ encryption:enable")
+
+    with subtest("Upload file and ensure it's encrypted"):
+        nextcloudwithopenssl1.succeed("${copySharedFile1}")
+        nextcloudwithopenssl1.succeed("grep -E '^HBEGIN:oc_encryption_module' /var/lib/nextcloud/data/root/files/test-shared-file")
+        nextcloudwithopenssl1.succeed("${withRcloneEnv1} ${pkgs.rclone}/bin/rclone cat nextcloud:test-shared-file | grep hi")
+
+    with subtest("Switch to OpenSSL 3"):
+        nextcloudwithopenssl1.succeed("${openssl3-node}/bin/switch-to-configuration test")
+        nextcloudwithopenssl1.wait_for_open_port(80)
+        nextcloudwithopenssl1.succeed("nextcloud-occ status")
+
+    with subtest("Existing encrypted files cannot be read, but new files can be added"):
+        nextcloudwithopenssl1.fail("${withRcloneEnv3} ${pkgs.rclone}/bin/rclone cat nextcloud:test-shared-file >&2")
+        nextcloudwithopenssl1.succeed("nextcloud-occ encryption:disable")
+        nextcloudwithopenssl1.succeed("${copySharedFile3}")
+        nextcloudwithopenssl1.succeed("grep bye /var/lib/nextcloud/data/root/files/test-shared-file2")
+        nextcloudwithopenssl1.succeed("${withRcloneEnv3} ${pkgs.rclone}/bin/rclone cat nextcloud:test-shared-file2 | grep bye")
+
+    with subtest("Switch back to OpenSSL 1.1 and ensure that encrypted files are readable again"):
+        nextcloudwithopenssl1.succeed("${openssl1-node}/bin/switch-to-configuration test")
+        nextcloudwithopenssl1.wait_for_open_port(80)
+        nextcloudwithopenssl1.succeed("nextcloud-occ status")
+        nextcloudwithopenssl1.succeed("nextcloud-occ encryption:enable")
+        nextcloudwithopenssl1.succeed("${withRcloneEnv1} ${pkgs.rclone}/bin/rclone cat nextcloud:test-shared-file2 | grep bye")
+        nextcloudwithopenssl1.succeed("${withRcloneEnv1} ${pkgs.rclone}/bin/rclone cat nextcloud:test-shared-file | grep hi")
+        nextcloudwithopenssl1.succeed("grep -E '^HBEGIN:oc_encryption_module' /var/lib/nextcloud/data/root/files/test-shared-file")
+        nextcloudwithopenssl1.succeed("grep bye /var/lib/nextcloud/data/root/files/test-shared-file2")
+
+    with subtest("Ensure that everything can be decrypted"):
+        nextcloudwithopenssl1.succeed("echo y | nextcloud-occ encryption:decrypt-all >&2")
+        nextcloudwithopenssl1.succeed("${withRcloneEnv1} ${pkgs.rclone}/bin/rclone cat nextcloud:test-shared-file2 | grep bye")
+        nextcloudwithopenssl1.succeed("${withRcloneEnv1} ${pkgs.rclone}/bin/rclone cat nextcloud:test-shared-file | grep hi")
+        nextcloudwithopenssl1.succeed("grep -vE '^HBEGIN:oc_encryption_module' /var/lib/nextcloud/data/root/files/test-shared-file")
+
+    with subtest("Switch to OpenSSL 3 ensure that all files are usable now"):
+        nextcloudwithopenssl1.succeed("${openssl3-node}/bin/switch-to-configuration test")
+        nextcloudwithopenssl1.wait_for_open_port(80)
+        nextcloudwithopenssl1.succeed("nextcloud-occ status")
+        nextcloudwithopenssl1.succeed("${withRcloneEnv3} ${pkgs.rclone}/bin/rclone cat nextcloud:test-shared-file2 | grep bye")
+        nextcloudwithopenssl1.succeed("${withRcloneEnv3} ${pkgs.rclone}/bin/rclone cat nextcloud:test-shared-file | grep hi")
+
+    nextcloudwithopenssl1.shutdown()
+  '';
+})) args

pkgs/development/interpreters/php/generic.nix

···
               [ ]
               allExtensionFunctions;
 
-          getExtName = ext: lib.removePrefix "php-" (builtins.parseDrvName ext.name).name;
+          getExtName = ext: ext.extensionName;
 
           # Recursively get a list of all internal dependencies
           # for a list of extensions.

pkgs/top-level/php-packages.nix

···
   # will mark the extension as a zend extension or not.
   mkExtension = lib.makeOverridable
     ({ name
-    , configureFlags ? [ "--enable-${name}" ]
+    , configureFlags ? [ "--enable-${extName}" ]
     , internalDeps ? [ ]
     , postPhpize ? ""
     , buildInputs ? [ ]
     , zendExtension ? false
     , doCheck ? true
+    , extName ? name
     , ...
     }@args: stdenv.mkDerivation ((builtins.removeAttrs args [ "name" ]) // {
       pname = "php-${name}";
-      extensionName = name;
+      extensionName = extName;
 
       outputs = [ "out" "dev" ];
 
···
 
       cdToExtensionRootPhase = ''
         # Go to extension source root.
-        cd "ext/${name}"
+        cd "ext/${extName}"
       '';
 
       preConfigure = ''
···
         runHook preInstall
 
         mkdir -p $out/lib/php/extensions
-        cp modules/${name}.so $out/lib/php/extensions/${name}.so
+        cp modules/${extName}.so $out/lib/php/extensions/${extName}.so
         mkdir -p $dev/include
         ${rsync}/bin/rsync -r --filter="+ */" \
                               --filter="+ *.h" \
···
         # without a specific openssl.cnf file
         {
           name = "openssl-legacy";
+          extName = "openssl";
           buildInputs = [ openssl_1_1 ];
           configureFlags = [ "--with-openssl" ];
           doCheck = false;