one-time passwords (e.g. for public file shares)

[theCalcaholic]

• Requires: Refactor: Centralize logic for checking if a share is password protected #61946
• Partially solves: Extendible anonymous sharing authentication options #38906
• Related: Allow temporary email passwords to be one-time use only #32353
• Related: External verification of Share (via Link) #44406

Summary

This PR adds one-time password management to Nextcloud server and integrates them with the files_sharing app.

(the actual form in the screenshot is part of #61733)

Notes

• This PR only changes <60 files. The huge amount of changes comes from rebuilding the frontend (make build-js-production).
• There is a second otp provider available as a Nextcloud app over at otp_provider_debug, which basically just logs OTPs to the Nextcloud logs. This could be helpful for testing/debugging and I would suggest moving it to the nextcloud namespace once this is merged (unless you don't consider it necessary). The main advantage is that you can test OTPs without setting up SMTP. However, I will not keep maintaining it, because that would require tracking changes to the OTP API and testing every new Nextcloud version.
• This PR should be merged after the refactoring of IShare->isPasswordProtected() (Refactor: Centralize logic for checking if a share is password protected #61946)

TODO

• (core) Implement OTP core functionality
• (core) Implement OTP integration into shares
• (files_sharing) Implement creation of OTP protected shares via OCS
• (files_sharing) Implement retrieval of public OTP protected shares via OCS
• Harden bruteforce settings for endpoints
• Tests
• Linting
• Regenerate openapi definitions for files_sharing
• Contribute documentation for the feature

Architecture and Rationale

General concepts

OTPs (one-time password) are short-lived, single use credentials sent to users via an (according to a given threat model) trusted channel (e.g. a specific email address).

OTP Providers define a method of sending OTPs to users.

OTP Recipients are valid address definitions within the scope of an OTP provider that can be sent OTPs.

Core/Server Changes

Generic

One-time passwords are implemented with generic interfaces so that they can be used by other parts of Nextcloud than sharing.

The core functionality for one-time passwords is implemented within the \OCP and \OC namespaces. OTPs are stored within a new database table one_time_password and have a providerID, a recipient string, an expiration date and a password. The idea here is, that the OTP configuration (i.e. provider+recipient) can be long lived, while the credentials (password+expiration date) are (re-)generated per use.
Management of OTPs is implemented in \OC\OneTimePassword\Manager (implementing the injectable interface at \OCP\OneTimePassword\IManager).

\OCP\Security\PasswordContext has been extended by an OTP case to allow the creation of password policies specifically for OTPs.

Events are used to allow apps to register OTP providers. They need to hook into the GetOneTimePasswordProviders and the SendOneTimePassword events to provider their functionality. Providers also need to implement the interface \OCP\OneTimePassword\IOneTimePasswordProvider, which defines methods that allow the Manager to select providers and provide information about them.

Sharing specific

Shares (see \OCP\Share\IShare) have been extended with an one_time_password field.

The \OC\Share20\Manager has been adjusted to prioritize OTPs when checking the authentication for a share.

The template publicshareauth.php has been adjusted to receive and display OTP related information (used in #61733 to show the OTP specific password form).

files_sharing Changes

The ShareAPIController has been extended to allow creating and updating OTP protected shares and returning the otp configuration when fetching shares. OTPs and passwords are mutually exclusive and an error will be returned when attempting to create a share with both.

The ShareController has been extended to supply template responses for public shares with otp related information.

A new ShareOTPController has been implemented that allows users to request OTPs for a share.

OTP Providers

An OTP provider, which allows sending OTPs via email has been implemented as (core) app: otp_provider_email. It can be disabled or restricted by administrators to disallow this functionality.

UI changes

The authentication page for public shares has been updated to accommodate OTPs (see screenshot).
When an OTP is required for a share, the authentication form will change to present a button for requesting an OTP in addition to the normal password field. It will also display a different title above the password field.

Password authentication page for OTP protected shares

The email template for sending OTPs to users is located in apps/otp_provider_email/lib/listener/SendOneTimePasswordEventListener.php and uses Nextclouds usual Mailer interface for templating emails.

Example OTP email sent to users

The logo is not displayed, because I'm testing with a local Nextcloud instance at a non-public URL.

The custom permissions in the sidebar sharing tab (files->sidebar->sharing->custom permissions) has been adjusted to allow choosing between no password protection, setting a normal password and configuring an OTP. The descriptions of the OTP are defined and localized by the OTP provider.

New UI for selecting an authentication method during share creation

Previous UI for selecting an auth method for comparison

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)
• Labels added where applicable (ex: bug/enhancement, 3. to review, feature component)
• Milestone added for target branch/version (ex: 32.x for stable32)

AI (if applicable)

• The content of this PR was partly or fully generated using AI

[theCalcaholic]

I am now done with the backend portion, so from my side, this PR is ready for review. :)

The only thing missing, is documentation, but I would want to wait for feedback before working on that.

Let me know if there is anything you require from me.

For manual testing, I recommend to use the frontend branch instead, which is based offf of this branch (see #61733).

Here are curl commands to create an OTP protected share on a Nextcloud instance running at http://nextcloud.local with user=admin and password=admin (requires the otp_provider_debug and otp_provider_email apps to be enabled):

For email:

curl http://nextcloud.local/ocs/v2.php/apps/files_sharing/api/v1/shares -u 'admin:admin' -H 'Content-Type: application/json' -H "Accept: application/json" -H "OCS-APIRequest: true" --data '{"path": "/Nextcloud_Server_Administration_Manual.pdf", "attributes": "[]", "shareType": 3, "otpProvider": "email", "otpRecipient": "your@email.address"}'

For debug (OTPs will be written to Nextcloud logs):

curl http://nextcloud.local/ocs/v2.php/apps/files_sharing/api/v1/shares -u 'admin:admin' -H 'Content-Type: application/json' -H "Accept: application/json" -H "OCS-APIRequest: true" --data '{"path": "/Nextcloud_Server_Administration_Manual.pdf", "attributes": "[]", "shareType": 3, "otpProvider": "debug", "otpRecipient": "foobar"}'

If the file /Nextcloud_Server_Administration_Manual.pdf doesn't exist for your user, you will need to use a different path.

[theCalcaholic]

@susnux I hope it's ok to tag you (I wasn't sure if the update messages above would reach you otherwise).