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Improve error reporting and logging when processing remote accounts (#15605)

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* Add a more descriptive PrivateNetworkAddressError exception class

* Remove unnecessary exception class to rescue clause

* Remove unnecessary include to JsonLdHelper

* Give more neutral error message when too many webfinger redirects

* Remove unnecessary guard condition

* Rework how “ActivityPub::FetchRemoteAccountService” handles errors

Add “suppress_errors” keyword argument to avoid raising errors in
ActivityPub::FetchRemoteAccountService#call (default/previous behavior).

* Rework how “ActivityPub::FetchRemoteKeyService” handles errors

Add “suppress_errors” keyword argument to avoid raising errors in
ActivityPub::FetchRemoteKeyService#call (default/previous behavior).

* Fix Webfinger::RedirectError not being a subclass of Webfinger::Error

* Add suppress_errors option to ResolveAccountService

Defaults to true (to preserve previous behavior). If set to false,
errors will be raised instead of caught, allowing the caller to be
informed of what went wrong.

* Return more precise error when failing to fetch account signing AP payloads

* Add tests

* Fixes

* Refactor error handling a bit

* Fix various issues

* Add specific error when provided Digest is not 256 bits of base64-encoded data

* Please CodeClimate

* Improve webfinger error reporting
This commit is contained in:
Claire 2022-09-20 23:30:26 +02:00 • committed by GitHub
parent 14c7c9e40e
commit 1145dbd327
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10 changed files with 158 additions and 47 deletions
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46
app/controllers/concerns/signature_verification.rb
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@ -93,11 +93,15 @@ module SignatureVerification
return account unless verify_signature(account, signature, compare_signed_string).nil?
@signature_verification_failure_reason = "Verification failed for #{account.username}@#{account.domain} #{account.uri} using rsa-sha256 (RSASSA-PKCS1-v1_5 with SHA-256)"
@signed_request_account = nil
fail_with! "Verification failed for #{account.username}@#{account.domain} #{account.uri} using rsa-sha256 (RSASSA-PKCS1-v1_5 with SHA-256)"
rescue SignatureVerificationError => e
@signature_verification_failure_reason = e.message
@signed_request_account = nil
fail_with! e.message
rescue HTTP::Error, OpenSSL::SSL::SSLError => e
fail_with! "Failed to fetch remote data: #{e.message}"
rescue Mastodon::UnexptectedResponseError
fail_with! 'Failed to fetch remote data (got unexpected reply from server)'
rescue Stoplight::Error::RedLight
fail_with! 'Fetching attempt skipped because of recent connection failure'
end
def request_body
@ -106,6 +110,11 @@ module SignatureVerification
private
def fail_with!(message)
@signature_verification_failure_reason = message
@signed_request_account = nil
end
def signature_params
@signature_params ||= begin
raw_signature = request.headers['Signature']
@ -138,7 +147,17 @@ module SignatureVerification
digests = request.headers['Digest'].split(',').map { |digest| digest.split('=', 2) }.map { |key, value| [key.downcase, value] }
sha256 = digests.assoc('sha-256')
raise SignatureVerificationError, "Mastodon only supports SHA-256 in Digest header. Offered algorithms: #{digests.map(&:first).join(', ')}" if sha256.nil?
raise SignatureVerificationError, "Invalid Digest value. Computed SHA-256 digest: #{body_digest}; given: #{sha256[1]}" if body_digest != sha256[1]
return if body_digest == sha256[1]
digest_size = begin
Base64.strict_decode64(sha256[1].strip).length
rescue ArgumentError
raise SignatureVerificationError, "Invalid Digest value. The provided Digest value is not a valid base64 string. Given digest: #{sha256[1]}"
end
raise SignatureVerificationError, "Invalid Digest value. The provided Digest value is not a SHA-256 digest. Given digest: #{sha256[1]}" if digest_size != 32
raise SignatureVerificationError, "Invalid Digest value. Computed SHA-256 digest: #{body_digest}; given: #{sha256[1]}"
end
def verify_signature(account, signature, compare_signed_string)
@ -216,19 +235,20 @@ module SignatureVerification
end
if key_id.start_with?('acct:')
stoplight_wrap_request { ResolveAccountService.new.call(key_id.gsub(/\Aacct:/, '')) }
stoplight_wrap_request { ResolveAccountService.new.call(key_id.gsub(/\Aacct:/, ''), suppress_errors: false) }
elsif !ActivityPub::TagManager.instance.local_uri?(key_id)
account = ActivityPub::TagManager.instance.uri_to_resource(key_id, Account)
account ||= stoplight_wrap_request { ActivityPub::FetchRemoteKeyService.new.call(key_id, id: false) }
account ||= stoplight_wrap_request { ActivityPub::FetchRemoteKeyService.new.call(key_id, id: false, suppress_errors: false) }
account
end
rescue Mastodon::HostValidationError
nil
rescue Mastodon::PrivateNetworkAddressError => e
raise SignatureVerificationError, "Requests to private network addresses are disallowed (tried to query #{e.host})"
rescue Mastodon::HostValidationError, ActivityPub::FetchRemoteAccountService::Error, ActivityPub::FetchRemoteKeyService::Error, Webfinger::Error => e
raise SignatureVerificationError, e.message
end
def stoplight_wrap_request(&block)
Stoplight("source:#{request.remote_ip}", &block)
.with_fallback { nil }
.with_threshold(1)
.with_cool_off_time(5.minutes.seconds)
.with_error_handler { |error, handle| error.is_a?(HTTP::Error) || error.is_a?(OpenSSL::SSL::SSLError) ? handle.call(error) : raise(error) }
@ -237,6 +257,10 @@ module SignatureVerification
def account_refresh_key(account)
return if account.local? || !account.activitypub?
ActivityPub::FetchRemoteAccountService.new.call(account.uri, only_key: true)
ActivityPub::FetchRemoteAccountService.new.call(account.uri, only_key: true, suppress_errors: false)
rescue Mastodon::PrivateNetworkAddressError => e
raise SignatureVerificationError, "Requests to private network addresses are disallowed (tried to query #{e.host})"
rescue Mastodon::HostValidationError, ActivityPub::FetchRemoteAccountService::Error, Webfinger::Error => e
raise SignatureVerificationError, e.message
end
end