Clicking the confirmation link multiple times currently leads to entering
account settings, which can be confusing. This commit changes that so that
it redirects to the root path, so it behaves the same way as clicking only
once in most cases.
* Update devise-two-factor to unreleased fork for Rails 6 support
Update tests to match new `rotp` version.
* Update nsa gem to unreleased fork for Rails 6 support
* Update rails to 6.1.3 and rails-i18n to 6.0
* Update to unreleased fork of pluck_each for Ruby 6 support
* Run "rails app:update"
* Add missing ActiveStorage config file
* Use config.ssl_options instead of removed ApplicationController#force_ssl
Disabled force_ssl-related tests as they do not seem to be easily testable
anymore.
* Fix nonce directives by removing Rails 5 specific monkey-patching
* Fix fixture_file_upload deprecation warning
* Fix yield-based test failing with Rails 6
* Use Rails 6's index_with when possible
* Use ActiveRecord::Cache::Store#delete_multi from Rails 6
This will yield better performances when deleting an account
* Disable Rails 6.1's automatic preload link headers
Since Rails 6.1, ActionView adds preload links for javascript files
in the Links header per default.
In our case, that will bloat headers too much and potentially cause
issues with reverse proxies. Furhermore, we don't need those links,
as we already output them as HTML link tags.
* Switch to Rails 6.0 default config
* Switch to Rails 6.1 default config
* Do not include autoload paths in the load path
* Use ActiveRecord::Result#to_ary instead of deprecated to_hash
They do the same thing, and to_hash has been removed from Rails 6.1
* Explicitly name polymorphic indexes to workaround a bug in Rails 6.1
cf. https://github.com/rails/rails/issues/41693
* Fix incorrect usage of “foreign_key” in migration script
* Use `ActiveModel::Errors#delete` instead of deprecated clear method
* Fix link headers tests on Rails 6.1
Rails 6.1 adds values to the Link header by default, thus it is not a
LinkHeader object anymore. Fix the test to parse the Link header instead
of assuming it is a LinkHeader.
* Fix crash on receiving requests with missing Digest header
Return an error pointing out that Digest is missing, instead of crashing.
Fixes#15743
* Fix from review feedback
An uncommon but somewhat difficult to digagnose issue is dealing with
improperly-seeded databases. In such cases, instance-signed fetches will
fail with a ActiveRecord::RecordNotFound error, usually caught and handled
as generic 404, leading people to think the remote resource itself has not
been found, while it's the local instance actor that does not exist.
This commit changes the code so that failure to find the instance actor
automatically creates a new one, so that improperly-seeded databases do
not cause any issue.
This also skips fetching the actor completely.
This will be useful if we end up distributing Update activities linked to
account suspensions more widely (they are currently only delivered to
the suspended account's followers), as currently, instances not knowing
about the suspended account would fetch it to then process the suspension.
Co-authored-by: Claire <claire.github-309c@sitedethib.com>
* Add honeypot fields to limit non-specialized spam
Add two honeypot fields: a fake website input and a fake password confirmation
one. The label/placeholder/aria-label tells not to fill them, and they are
hidden in CSS, so legitimate users should not fall into these.
This should cut down on some non-Mastodon-specific spambots.
* Require a 3 seconds delay before submitting the registration form
* Fix tests
* Move registration form time check to model validation
* Give people a chance to clear the honeypot fields
* Refactor honeypot translation strings
Co-authored-by: Claire <claire.github-309c@sitedethib.com>
If someone tries logging in to an account and is prompted for a 2FA
code or sign-in token, even if the account's password or e-mail is
updated in the meantime, the session will show the prompt and allow
the login process to complete with a valid 2FA code or sign-in token
* Add more specific error message when request body digest is invalid
This may help other implementors debug their implementation.
* Relax Host parameter requirement to GET requests
The only POST requests processed by Mastodon need objects/actors (including
their host) to be explicitly mentioned in the request's body, so replaying
a legitimate request to another host should not be a security issue.
* Support Digest headers using multiple algorithms or lowercase alogirthm names
* Add support for followers synchronization on the receiving end
Check the `collectionSynchronization` attribute on `Create` and `Announce`
activities and synchronize followers from provided collection if possible.
* Add tests for followers synchronization on the receiving end
* Add support for follower synchronization on the sender's end
* Add tests for the sending end
* Switch from AS attributes to HTTP header
Replace the custom `collectionSynchronization` ActivityStreams attribute by
an HTTP header (`X-AS-Collection-Synchronization`) with the same syntax as
the `Signature` header and the following fields:
- `collectionId` to specify which collection to synchronize
- `digest` for the SHA256 hex-digest of the list of followers known on the
receiving instance (where “receiving instance” is determined by accounts
sharing the same host name for their ActivityPub actor `id`)
- `url` of a collection that should be fetched by the instance actor
Internally, move away from the webfinger-based `domain` attribute and use
account `uri` prefix to group accounts.
* Add environment variable to disable followers synchronization
Since the whole mechanism relies on some new preconditions that, in some
extremely rare cases, might not be met, add an environment variable
(DISABLE_FOLLOWERS_SYNCHRONIZATION) to disable the mechanism altogether and
avoid followers being incorrectly removed.
The current conditions are:
1. all managed accounts' actor `id` and inbox URL have the same URI scheme and
netloc.
2. all accounts whose actor `id` or inbox URL share the same URI scheme and
netloc as a managed account must be managed by the same Mastodon instance
as well.
As far as Mastodon is concerned, breaking those preconditions require extensive
configuration changes in the reverse proxy and might also cause other issues.
Therefore, this environment variable provides a way out for people with highly
unusual configurations, and can be safely ignored for the overwhelming majority
of Mastodon administrators.
* Only set follower synchronization header on non-public statuses
This is to avoid unnecessary computations and allow Follow-related
activities to be handled by the usual codepath instead of going through
the synchronization mechanism (otherwise, any Follow/Undo/Accept activity
would trigger the synchronization mechanism even if processing the activity
itself would be enough to re-introduce synchronization)
* Change how ActivityPub::SynchronizeFollowersService handles follow requests
If the remote lists a local follower which we only know has sent a follow
request, consider the follow request as accepted instead of sending an Undo.
* Integrate review feeback
- rename X-AS-Collection-Synchronization to Collection-Synchronization
- various minor refactoring and code style changes
* Only select required fields when computing followers_hash
* Use actor URI rather than webfinger domain in synchronization endpoint
* Change hash computation to be a XOR of individual hashes
Makes it much easier to be memory-efficient, and avoid sorting discrepancy issues.
* Marginally improve followers_hash computation speed
* Further improve hash computation performances by using pluck_each
* Add bell button
Fix#4890
* Remove duplicate type from post-deployment migration
* Fix legacy class type mappings
* Improve query performance with better index
* Fix validation
* Remove redundant index from notifications
* Do not serve account actors at all in limited federation mode
When an account is fetched without a signature from an allowed instance,
return an error.
This isn't really an improvement in security, as the only information that was
previously returned was required protocol-level info, and the only personal bit
was the existence of the account. The existence of the account can still be
checked by issuing a webfinger query, as those are accepted without signatures.
However, this change makes it so that unallowed instances won't create account
records on their end when they find a reference to an unknown account.
The previous behavior of rendering a limited list of fields, instead of not
rendering the actor at all, was in order to prevent situations in which two
instances in Authorized Fetch mode or Limited Federation mode would fail to
reach each other because resolving an account would require a signed query…
from an account which can only be fetched with a signed query itself. However,
this should now be fine as fetching accounts is done by signing on behalf of
the special instance actor, which does not require any kind of valid signature
to be fetched.
* Fix tests
* Add database support for list show-reply preferences
* Add backend support to read and update list-specific show_replies settings
* Add basic UI to set list replies setting
* Add specs for list replies policy
* Switch "cycling" reply policy link to a set of radio inputs
* Capitalize replies_policy strings
* Change radio button design to be consistent with that of the directory explorer
* Make Array-creation behavior of Paginable more predictable
Paginable.paginate_by_id usually returns ActiveRecord::Relation, but it
returns an Array if min_id option is present. The behavior caused problems
fixed with the following commits:
- 552e886b64
- b63ede5005
- 64ef37b89d
To prevent from recurring similar problems, this commit introduces two
changes:
- The scope now always returns an Array whether min_id option is present
or not.
- The scope is renamed to to_a_paginated_by_id to clarify it returns an
Array.
* Transform Paginable.to_a_paginated_by_id from a scope to a class method
https://api.rubyonrails.org/classes/ActiveRecord/Scoping/Named/ClassMethods.html#method-i-scope
> The method is intended to return an ActiveRecord::Relation object, which
> is composable with other scopes.
Paginable.to_a_paginated_by_id returns an Array and is not appropriate
as a scope.
* Replace incorrect use of distinct with group
Some uses of ActiveRecord::QueryMethods#distinct pass field names but they
are incorrect for the current version of Rails.
ActiveRecord::QueryMethods#group provides the expected behavior and
benefits performance. See commit 6da24aad4cafdef8d8a2c92bac2002a5fc2fe9c8.
* Introduce ApplicationController#cache_collection_paginated_by_id
ApplicationController#cache_collection_paginated_by_id fuses
ApplicationController#cache_collection and Paginable.paginate_by_id.
An advantage of this method is that it prevents from modifying scope which
Paginable.paginate_by_id may provide.
ApplicationController#cache_collection always return an array and there
is no possibility of the scope modification. It is also clear for a
programmer, considering the implication of "cache".
This method can also emit more efficient queries by using
Cacheable.cache_ids before calling Paginable.paginate_by_id.
Some uses of ActiveRecord::QueryMethods#distinct pass field names but they
are incorrect for the current version of Rails.
ActiveRecord::QueryMethods#group provides the expected behavior and
benefits performance. See commit 6da24aad4cafdef8d8a2c92bac2002a5fc2fe9c8.
The old implementation had two queries:
1. The query constructed in Api::V1::FavouritesController#results
2. The query constructed in #cached_favourites, which is merged with 1.
Both of them are issued againt PostgreSQL. The combination of the two
queries caused the following problems:
- The small window between the two queries involves race conditions.
- Minor performance inefficiency.
Moreover, the construction of query 2, which involves merging with query
1 has a bug. Query 1 is finalized with paginate_by_id, but paginate_by_id
returns an array when min_id parameter is specified. The behavior prevents
from merging the query, and in the real world, ActiveRecord simply ignores
the merge (!), which results in querying the entire scan of statuses and
favourites table.
This change fixes these issues by simply letting query 1 get all the works
done.
DISTINCT clause removes duplicated records according to all the selected
attributes. In reality, it can remove duplicated records only looking at
statuses.id, but the clause confuses the query planner and yields
insufficient performance.
The behavior is also problematic if the scope produced by HashQueryService
is used to query columns without id (using pluck method, for example). The
scope is expected to contain unique statuses, but the uniquness will be
evaluated with some arbitrary columns other than id.
GROUP BY clause resolves those problem by explicitly specifying the
column to take into account for the record distinction.
A workaround for the problem of DISTINCT clause in
Api::V1::Timelines::TagController is no longer necessary and removed.
* Add support for latest HTTP Signatures spec draft
https://www.ietf.org/id/draft-ietf-httpbis-message-signatures-00.html
- add support for the “hs2019” signature algorithm (assumed to be equivalent
to RSA-SHA256, since we do not have a mechanism to specify the algorithm
within the key metadata yet)
- add support for (created) and (expires) pseudo-headers and related
signature parameters, when using the hs2019 signature algorithm
- adjust default “headers” parameter while being backwards-compatible with
previous implementation
- change the acceptable time window logic from 12 hours surrounding the “date”
header to accepting signatures created up to 1 hour in the future and
expiring up to 1 hour in the past (but only allowing expiration dates up to
12 hours after the creation date)
This doesn't conform with the current draft, as it doesn't permit accounting
for clock skew.
This, however, should be addressed in a next version of the draft:
https://github.com/httpwg/http-extensions/pull/1235
* Add additional signature requirements
* Rewrite signature params parsing using Parslet
* Make apparent which signature algorithm Mastodon on verification failure
Mastodon uses RSASSA-PKCS1-v1_5, which is not recommended for new applications,
and new implementers may thus unknowingly use RSASSA-PSS.
* Add workaround for PeerTube's invalid signature header
The previous parser allowed incorrect Signature headers, such as
those produced by old versions of the `http-signature` node.js package,
and seemingly used by PeerTube.
This commit adds a workaround for that.
* Fix `signature_key_id` raising an exception
Previously, parsing failures would result in `signature_key_id` being nil,
but the parser changes made that result in an exception.
This commit changes the `signature_key_id` method to return `nil` in case
of parsing failures.
* Move extra HTTP signature helper methods to private methods
* Relax (request-target) requirement to (request-target) || digest
This lets requests from Plume work without lowering security significantly.
* feat: add possibility of adding WebAuthn security keys to use as 2FA
This adds a basic UI for enabling WebAuthn 2FA. We did a little refactor
to the Settings page for editing the 2FA methods – now it will list the
methods that are available to the user (TOTP and WebAuthn) and from
there they'll be able to add or remove any of them.
Also, it's worth mentioning that for enabling WebAuthn it's required to
have TOTP enabled, so the first time that you go to the 2FA Settings
page, you'll be asked to set it up.
This work was inspired by the one donde by Github in their platform, and
despite it could be approached in different ways, we decided to go with
this one given that we feel that this gives a great UX.
Co-authored-by: Facundo Padula <facundo.padula@cedarcode.com>
* feat: add request for WebAuthn as second factor at login if enabled
This commits adds the feature for using WebAuthn as a second factor for
login when enabled.
If users have WebAuthn enabled, now a page requesting for the use of a
WebAuthn credential for log in will appear, although a link redirecting
to the old page for logging in using a two-factor code will also be
present.
Co-authored-by: Facundo Padula <facundo.padula@cedarcode.com>
* feat: add possibility of deleting WebAuthn Credentials
Co-authored-by: Facundo Padula <facundo.padula@cedarcode.com>
* feat: disable WebAuthn when an Admin disables 2FA for a user
Co-authored-by: Facundo Padula <facundo.padula@cedarcode.com>
* feat: remove ability to disable TOTP leaving only WebAuthn as 2FA
Following examples form other platforms like Github, we decided to make
Webauthn 2FA secondary to 2FA with TOTP, so that we removed the
possibility of removing TOTP authentication only, leaving users with
just WEbAuthn as 2FA. Instead, users will have to click on 'Disable 2FA'
in order to remove second factor auth.
The reason for WebAuthn being secondary to TOPT is that in that way,
users will still be able to log in using their code from their phone's
application if they don't have their security keys with them – or maybe
even lost them.
* We had to change a little the flow for setting up TOTP, given that now
it's possible to setting up again if you already had TOTP, in order to
let users modify their authenticator app – given that now it's not
possible for them to disable TOTP and set it up again with another
authenticator app.
So, basically, now instead of storing the new `otp_secret` in the
user, we store it in the session until the process of set up is
finished.
This was because, as it was before, when users clicked on 'Edit' in
the new two-factor methods lists page, but then went back without
finishing the flow, their `otp_secret` had been changed therefore
invalidating their previous authenticator app, making them unable to
log in again using TOTP.
Co-authored-by: Facundo Padula <facundo.padula@cedarcode.com>
* refactor: fix eslint errors
The PR build was failing given that linting returning some errors.
This commit attempts to fix them.
* refactor: normalize i18n translations
The build was failing given that i18n translations files were not
normalized.
This commits fixes that.
* refactor: avoid having the webauthn gem locked to a specific version
* refactor: use symbols for routes without '/'
* refactor: avoid sending webauthn disabled email when 2FA is disabled
When an admins disable 2FA for users, we were sending two mails
to them, one notifying that 2FA was disabled and the other to notify
that WebAuthn was disabled.
As the second one is redundant since the first email includes it, we can
remove it and send just one email to users.
* refactor: avoid creating new env variable for webauthn_origin config
* refactor: improve flash error messages for webauthn pages
Co-authored-by: Facundo Padula <facundo.padula@cedarcode.com>
* Increase DNS timeout from 1 second to 5 seconds for MX check
1 seconds is rather short when using a recursive DNS resolver which
hasn't got a cached result already available. Use 5 seconds instead,
which is the timeout value we use for outgoing HTTP queries.
* Add more precise error messages for invalid e-mail addresses
* Add tests for some cachable responses
This only covers responses that we should have managed to make cachable
so far. It's not the case of all responses that should be cachable in
the end.
* Fix RSS feeds not being cachable
* Add toot send by current user at local state after send a new toot
Related to #14021
* Decrement toot counter at profile when remove a toot
Related to #14021
* Remove semicolon at end of line
While OAuth tokens were immediately revoked, accessing the home
controller immediately generated new OAuth tokens and "revived"
the session due to a combination of using remember_me tokens and
overwriting the `authenticate_user!` method
* Add UserNote model
* Add UI for user notes
* Put comment in relationships entity
* Add API to create user notes
* Copy user notes to new account when receiving a Move activity
* Address some of the review remarks
* Replace modal by inline edition
* Please CodeClimate
* Button design changes
* Change design again
* Cancel note edition when pressing Escape
* Fixes
* Tweak design again
* Move “Add note” item, and allow users to add notes to themselves
* Rename UserNote into AccountNote, rename “comment” Relationship attribute to “note”
- Change audio files to not be stripped of metadata
- Automatically extract cover art from audio if it exists
- Add `thumbnail` parameter to `POST /api/v1/media`, `POST /api/v2/media` and `PUT /api/v1/media/:id`
- Add `icon` to represent it in attachments in ActivityPub
- Fix `preview_url` containing URL of missing missing image when there is no thumbnail instead of null
- Fix duration of audio not being displayed on public pages until the file is loaded
* Display appropriate error when performing unpermitted operation on custom emoji
Fixes#13897
* Remove links to custom emoji actions not performable by moderators
When attempting to access the log-in page while already logged in,
Devise's `require_no_authentication` kicks in and sets a flash
message “You are already signed in.”
In almost all cases, this also causes a redirect to /web, which
does not display or clear flash messages, thus leaving the message
to a potentially much later date, like for instance, accessing
/preferences several minutes after being redirected to /web.
This is achieved by sending a DELETE request to
/settings/profile/pictures/{avatar,header} via a link that is part of
the upload form's hint of the respective picture.
* Fix 404 and 410 API errors being silently discarded in WebUI
Fixes#13278
* Return more appropriate error when user replies to a deleted toot
* Please CodeClimate
* Fix 404/410 errors on fetching account timelines & identity proofs
* Refactor error handling
* Move error message string to statuses.errors
* Change ActivityPub follower/following collections to not link first page
* Add support for hiding followers and following of remote users
* Switch to using a single `hide_collections` column
* Address code style remarks
`request.format` is not a symbol but a `Mime::Type`, so the condition actually
never matched, and a session was created even for those requests, preventing
caching.
Instead of returning a signature verification error, pretend there
was no signature (i.e., this does not allow access to resources that
need a valid signature), so public resources can still be fetched
Fix#13011
* Change meaning of /api/v1/announcements/:id/dismiss to mark an announcement as read
* Change how unread announcements are counted in UI
* Add unread marker to announcements and mark announcements as unread as they are displayed
* Fixups
Change `all_day` to be a visual client-side cue only
Publish immediately if `scheduled_at` is in the past
Add `published_at` and `updated_at` to announcements JSON
While making browser requests in the other sessions after a password
change or reset does not allow you to be logged in and correctly
invalidates the session making the request, sessions have API tokens
associated with them, which can still be used until that session
is invalidated.
This is a security issue for accounts that were already compromised
some other way because it makes it harder to throw out the hijacker.
* Add announcements
Fix#11006
* Add reactions to announcements
* Add admin UI for announcements
* Add unit tests
* Fix issues
- Add `with_dismissed` param to announcements API
- Fix end date not being formatted when time range is given
- Fix announcement delete causing reactions to send streaming updates
- Fix announcements container growing too wide and mascot too small
- Fix `all_day` being settable when no time range is given
- Change text "Update" to "Announcement"
* Fix scheduler unpublishing announcements before they are due
* Fix filter params not being passed to announcements filter
Allow browsing and filtering all relationships instead of just
followers, unify the codebase with the user-facing relationship
manager, add ability to see who the user invited
* Fix unused role routes being generated
* Remove unused JavaScript code
* Refactor filters code to be DRYer
* Fix `.count == 0` comparisons to `.empty?` in views
* Fix filters in views
* Hide blocked, muted, and blocked-by users from toot favourite lists
* Hide blocked, muted, and blocked-by users from toot reblog lists
* Hide blocked, muted, and blocked-by users from followers/following (API)
* Fix tests
* Hide blocked, muted, and blocked-by users from followers/following on public pages
* Add follow_request notification type
The notification type already existed in the backend but was never pushed
to the front-end. This also means translation strings were also available
for the backend, from the notification mailer.
Unlike other notification types, these are off by default, to match what
I remember of Gargron's view on the topic: that follow requests should not
clutter notifications and should instead be reviewed at the user's own
leisure in the dedicated column.
Since follow requests have their own column, I've deemed it unnecessary to
add a specific tab for them in the notification quick filter.
* Show follow request link in single-column if there are pending requests, even if account isn't locked
* Push follow requests from notifications to the follow_requests list
* Offer to accept or reject follow request from the notification
* Redesign follow request notification
* make it not return http 400 when passing and empty source argument
* create a spec for the empty source hash bug
* compact checks for nil, empty? parameters
* use nil.blank? instead checking for nil
* Add backend support for bookmarks
Bookmarks behave like favourites, except they aren't shared with other
users and do not have an associated counter.
* Add spec for bookmark endpoints
* Add front-end support for bookmarks
* Introduce OAuth scopes for bookmarks
* Add bookmarks to archive takeout
* Fix migration
* Coding style fixes
* Fix rebase issue
* Update bookmarked_statuses to latest UI changes
* Update bookmark actions to properly reflect status changes in state
* Add bookmarks item to single-column layout
* Make active bookmarks red
Change the behaviour of remotable concern. Previously, it would skip
downloading an attachment if the stored remote URL is identical to
the new one. Now it would not be skipped if the attachment is not
actually currently stored by Paperclip.
Fetching statuses from all followed accounts at once takes too long
within Postgres. Fetching them one by one and merging in Ruby
could be a lot less resource-intensive
Because the query for dynamically fetching the home timeline is so
heavy, we can no longer offer it when the home timeline is missing
* Add nodeinfo endpoint
* dont commit stuff from my local dev
* consistant naming since we implimented 2.1 schema
* Add some additional node info stuff
* Add nodeinfo endpoint
* dont commit stuff from my local dev
* consistant naming since we implimented 2.1 schema
* expanding this to include federation info
* codeclimate feedback
* CC feedback
* using activeserializers seems like a good idea...
* get rid of draft 2.1 version
* Reimplement 2.1, also fix metaData -> metadata
* Fix metaData -> metadata here too
* Fix nodeinfo 2.1 tests
* Implement cache for monthly user aggregate
* Useless
* Remove ostatus from the list of supported protocols
* Fix nodeinfo's open_registration reading obsolete setting variable
* Only serialize domain blocks with user-facing limitations
* Do not needlessly list noop severity in nodeinfo
* Only serialize domain blocks info in nodeinfo when they are set to be displayed to everyone
* Enable caching for nodeinfo endpoints
* Fix rendering nodeinfo
* CodeClimate fixes
* Please CodeClimate
* Change InstancePresenter#active_user_count_months for clarity
* Refactor NodeInfoSerializer#metadata
* Remove nodeinfo 2.1 support as the schema doesn't exist
* Clean-up
* Change silenced accounts to require approval on follow
* Also require approval for follows by people explicitly muted by target accounts
* Do not auto-accept silenced or muted accounts when switching from locked to unlocked
* Add `follow_requests_count` to verify_credentials
* Show “Follow requests” menu item if needed even if account is locked
* Add tests
* Correctly reflect that follow requests weren't auto-accepted when local account is silenced
* Accept follow requests from user-muted accounts to avoid leaking mutes
* Addition of update activity distribution by alias, minor correction
* Distribute Update activity after adding alias
* Add uniqueness verification to alias uri
* accept acct starting with @
* fix double-quoted to single-quoted
* Add search and sort functions to hashtag admin UI
* Move scope processing from tags_controller to tag_filter
* Fix based on method naming conventions
* Fixed not to get 500 errors for invalid requests
* Add soft delete for statuses to allow them to appear instant
* Allow reporting soft-deleted statuses and show them in the admin UI
* Change index for getting an account's statuses
The reason for unattaching media instead of removing it is to support
delete & redraft functionality, but remote or staff-removed statuses
will never be redrafted, so the media should be deleted immediately
* Add automatic blocklist display in /about/blocks
Inspired by https://github.com/Gargron/mastodon.social-misc
* Add admin option to set who can see instance blocks
* Normalize locales files
* Rename “Sandbox” to “Silence” for consistency
* Disable /about/blocks when in whitelist mode
* Optionally display rationale for domain blocks
* Only display domain blocks that have user-facing limitations, and order them
* Redesign table of blocked domains to better handle long domain names and rationales
* Change domain blocks ordering now that rationales aren't displayed right away
* Only show explanation for block severities actually in use
* Reword instance block explanations and add disclaimer for public fetch mode
