mastodon/app/lib/formatter.rb
Eugen Rochko 1787704e1c Improve signature verification safeguards (#8959)
* Downcase signed_headers string before building the signed string

The HTTP Signatures draft does not mandate the “headers” field to be downcased,
but mandates the header field names to be downcased in the signed string, which
means that prior to this patch, Mastodon could fail to process signatures from
some compliant clients. It also means that it would not actually check the
Digest of non-compliant clients that wouldn't use a lowercased Digest field
name.

Thankfully, I don't know of any such client.

* Revert "Remove dead code (#8919)"

This reverts commit a00ce8c92c.

* Restore time window checking, change it to 12 hours

By checking the Date header, we can prevent replaying old vulnerable
signatures. The focus is to prevent replaying old vulnerable requests
from software that has been fixed in the meantime, so a somewhat long
window should be fine and accounts for timezone misconfiguration.

* Escape users' URLs when formatting them

Fixes possible HTML injection

* Escape all string interpolations in Formatter class

Slightly improve performance by reducing class allocations
from repeated Formatter#encode calls

* Fix code style issues
2018-10-12 00:17:36 +02:00

253 lines
7.6 KiB
Ruby

# frozen_string_literal: true
require 'singleton'
require_relative './sanitize_config'
class Formatter
include Singleton
include RoutingHelper
include ActionView::Helpers::TextHelper
def format(status, **options)
if status.reblog?
prepend_reblog = status.reblog.account.acct
status = status.proper
else
prepend_reblog = false
end
raw_content = status.text
return '' if raw_content.blank?
unless status.local?
html = reformat(raw_content)
html = encode_custom_emojis(html, status.emojis, options[:autoplay]) if options[:custom_emojify]
return html.html_safe # rubocop:disable Rails/OutputSafety
end
linkable_accounts = status.mentions.map(&:account)
linkable_accounts << status.account
html = raw_content
html = "RT @#{prepend_reblog} #{html}" if prepend_reblog
html = encode_and_link_urls(html, linkable_accounts)
html = encode_custom_emojis(html, status.emojis, options[:autoplay]) if options[:custom_emojify]
html = simple_format(html, {}, sanitize: false)
html = html.delete("\n")
html.html_safe # rubocop:disable Rails/OutputSafety
end
def reformat(html)
sanitize(html, Sanitize::Config::MASTODON_STRICT)
end
def plaintext(status)
return status.text if status.local?
text = status.text.gsub(/(<br \/>|<br>|<\/p>)+/) { |match| "#{match}\n" }
strip_tags(text)
end
def simplified_format(account, **options)
html = account.local? ? linkify(account.note) : reformat(account.note)
html = encode_custom_emojis(html, account.emojis, options[:autoplay]) if options[:custom_emojify]
html.html_safe # rubocop:disable Rails/OutputSafety
end
def sanitize(html, config)
Sanitize.fragment(html, config)
end
def format_spoiler(status, **options)
html = encode(status.spoiler_text)
html = encode_custom_emojis(html, status.emojis, options[:autoplay])
html.html_safe # rubocop:disable Rails/OutputSafety
end
def format_display_name(account, **options)
html = encode(account.display_name.presence || account.username)
html = encode_custom_emojis(html, account.emojis, options[:autoplay]) if options[:custom_emojify]
html.html_safe # rubocop:disable Rails/OutputSafety
end
def format_field(account, str, **options)
return reformat(str).html_safe unless account.local? # rubocop:disable Rails/OutputSafety
html = encode_and_link_urls(str, me: true)
html = encode_custom_emojis(html, account.emojis, options[:autoplay]) if options[:custom_emojify]
html.html_safe # rubocop:disable Rails/OutputSafety
end
def linkify(text)
html = encode_and_link_urls(text)
html = simple_format(html, {}, sanitize: false)
html = html.delete("\n")
html.html_safe # rubocop:disable Rails/OutputSafety
end
private
def html_entities
@html_entities ||= HTMLEntities.new
end
def encode(html)
html_entities.encode(html)
end
def encode_and_link_urls(html, accounts = nil, options = {})
entities = Extractor.extract_entities_with_indices(html, extract_url_without_protocol: false)
if accounts.is_a?(Hash)
options = accounts
accounts = nil
end
rewrite(html.dup, entities) do |entity|
if entity[:url]
link_to_url(entity, options)
elsif entity[:hashtag]
link_to_hashtag(entity)
elsif entity[:screen_name]
link_to_mention(entity, accounts)
end
end
end
def count_tag_nesting(tag)
if tag[1] == '/' then -1
elsif tag[-2] == '/' then 0
else 1
end
end
def encode_custom_emojis(html, emojis, animate = false)
return html if emojis.empty?
emoji_map = if animate
emojis.map { |e| [e.shortcode, full_asset_url(e.image.url)] }.to_h
else
emojis.map { |e| [e.shortcode, full_asset_url(e.image.url(:static))] }.to_h
end
i = -1
tag_open_index = nil
inside_shortname = false
shortname_start_index = -1
invisible_depth = 0
while i + 1 < html.size
i += 1
if invisible_depth.zero? && inside_shortname && html[i] == ':'
shortcode = html[shortname_start_index + 1..i - 1]
emoji = emoji_map[shortcode]
if emoji
replacement = "<img draggable=\"false\" class=\"emojione\" alt=\":#{encode(shortcode)}:\" title=\":#{encode(shortcode)}:\" src=\"#{encode(emoji)}\" />"
before_html = shortname_start_index.positive? ? html[0..shortname_start_index - 1] : ''
html = before_html + replacement + html[i + 1..-1]
i += replacement.size - (shortcode.size + 2) - 1
else
i -= 1
end
inside_shortname = false
elsif tag_open_index && html[i] == '>'
tag = html[tag_open_index..i]
tag_open_index = nil
if invisible_depth.positive?
invisible_depth += count_tag_nesting(tag)
elsif tag == '<span class="invisible">'
invisible_depth = 1
end
elsif html[i] == '<'
tag_open_index = i
inside_shortname = false
elsif !tag_open_index && html[i] == ':'
inside_shortname = true
shortname_start_index = i
end
end
html
end
def rewrite(text, entities)
chars = text.to_s.to_char_a
# Sort by start index
entities = entities.sort_by do |entity|
indices = entity.respond_to?(:indices) ? entity.indices : entity[:indices]
indices.first
end
result = []
last_index = entities.reduce(0) do |index, entity|
indices = entity.respond_to?(:indices) ? entity.indices : entity[:indices]
result << encode(chars[index...indices.first].join)
result << yield(entity)
indices.last
end
result << encode(chars[last_index..-1].join)
result.flatten.join
end
def link_to_url(entity, options = {})
url = Addressable::URI.parse(entity[:url])
html_attrs = { target: '_blank', rel: 'nofollow noopener' }
html_attrs[:rel] = "me #{html_attrs[:rel]}" if options[:me]
Twitter::Autolink.send(:link_to_text, entity, link_html(entity[:url]), url, html_attrs)
rescue Addressable::URI::InvalidURIError, IDN::Idna::IdnaError
encode(entity[:url])
end
def link_to_mention(entity, linkable_accounts)
acct = entity[:screen_name]
return link_to_account(acct) unless linkable_accounts
account = linkable_accounts.find { |item| TagManager.instance.same_acct?(item.acct, acct) }
account ? mention_html(account) : "@#{encode(acct)}"
end
def link_to_account(acct)
username, domain = acct.split('@')
domain = nil if TagManager.instance.local_domain?(domain)
account = EntityCache.instance.mention(username, domain)
account ? mention_html(account) : "@#{encode(acct)}"
end
def link_to_hashtag(entity)
hashtag_html(entity[:hashtag])
end
def link_html(url)
url = Addressable::URI.parse(url).to_s
prefix = url.match(/\Ahttps?:\/\/(www\.)?/).to_s
text = url[prefix.length, 30]
suffix = url[prefix.length + 30..-1]
cutoff = url[prefix.length..-1].length > 30
"<span class=\"invisible\">#{encode(prefix)}</span><span class=\"#{cutoff ? 'ellipsis' : ''}\">#{encode(text)}</span><span class=\"invisible\">#{encode(suffix)}</span>"
end
def hashtag_html(tag)
"<a href=\"#{encode(tag_url(tag.downcase))}\" class=\"mention hashtag\" rel=\"tag\">#<span>#{encode(tag)}</span></a>"
end
def mention_html(account)
"<span class=\"h-card\"><a href=\"#{encode(TagManager.instance.url_for(account))}\" class=\"u-url mention\">@<span>#{encode(account.username)}</span></a></span>"
end
end