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fix source dedup breaking with port wildcards #490

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fix source dedup breaking with port wildcards #490

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12 changes: 10 additions & 2 deletions lib/secure_headers/headers/content_security_policy.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -154,10 +154,10 @@ def reject_all_values_if_none(source_list)
# e.g. *.fd.fxlcf.dpdns.org asdf.github.com becomes *.fd.fxlcf.dpdns.org
def dedup_source_list(sources)
sources = sources.uniq
wild_sources = sources.select { |source| source =~ STAR_REGEXP }
wild_sources = sources.select { |source| source =~ DOMAIN_WILDCARD_REGEX || source =~ PORT_WILDCARD_REGEX }

if wild_sources.any?
schemes = sources.map { |source| [source, URI(source).scheme] }.to_h
schemes = sources.map { |source| [source, source_scheme(source)] }.to_h
sources.reject do |source|
!wild_sources.include?(source) &&
wild_sources.any? { |pattern| schemes[pattern] == schemes[source] && File.fnmatch(pattern, source) }
Expand Down Expand Up @@ -212,5 +212,13 @@ def strip_source_schemes(source_list)
def symbol_to_hyphen_case(sym)
sym.to_s.tr("_", "-")
end

def source_scheme(source)
uri = URI(source.sub(PORT_WILDCARD_REGEX, ""))
# If host is nil the given source doesn't contain a scheme
# e.g. for `example.org:443` it would return `example.org` as the scheme
# which is of course incorrect
uri.scheme if uri.host
Comment on lines +217 to +221
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@lgarron lgarron Aug 16, 2022 •
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It turns out that this also fails for URLs like https://*.example.org:*

What do you think of hardcoding just HTTP and HTTPS to avoid further wildcard issues?

Suggested change
uri = URI(source.sub(PORT_WILDCARD_REGEX, ""))
# If host is nil the given source doesn't contain a scheme
# e.g. for `example.org:443` it would return `example.org` as the scheme
# which is of course incorrect
uri.scheme if uri.host
return "https" if source.start_with?("https://")
return "http" if source.start_with?("http://")
nil

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@lgarron lgarron Aug 16, 2022 •
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Actually, that will result in incorrect deduplication because of the code higher up. So I'd lean more towards just matching ^([A-Za-z0-9\-\+.]+):\/\/, which should return the correct scheme if a valid URL pattern is passed in.

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@machisuji machisuji Aug 16, 2022

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Yeah I agree. I'll add a test case for that today and change it to the regex you suggested.

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@machisuji machisuji Aug 17, 2022 •
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Actually having looked into it again I don't quite get what the issue is. Parsing https://*.example.org:* would indeed fail but this is why in line 217 uri = URI(source.sub(PORT_WILDCARD_REGEX, "")) it removes the port wildcard.

irb(main):003:0> PORT_WILDCARD_REGEX = /:\*/
=> /:\*/
irb(main):004:0> source = "https://*.example.org:*"
=> "https://*.example.org:*"
irb(main):005:0> URI(source.sub(PORT_WILDCARD_REGEX, ""))
=> #<URI::HTTPS https://*.example.org>
irb(main):006:0> _.scheme
=> "https"

So the source_scheme method does return the correct result for "https://*.example.org:*".

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@lgarron lgarron Aug 17, 2022 •
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FYI, I've tried to give this whole code a refactor at #498

end
end
end
3 changes: 2 additions & 1 deletion lib/secure_headers/headers/policy_management.rb
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Expand Up @@ -152,7 +152,8 @@ def self.included(base)

FETCH_SOURCES = ALL_DIRECTIVES - NON_FETCH_SOURCES - NON_SOURCE_LIST_SOURCES

STAR_REGEXP = Regexp.new(Regexp.escape(STAR))
DOMAIN_WILDCARD_REGEX = /(?<=\A|[^:])\*/
PORT_WILDCARD_REGEX = /:\*/
HTTP_SCHEME_REGEX = %r{\Ahttps?://}

WILDCARD_SOURCES = [
Expand Down
13 changes: 12 additions & 1 deletion spec/lib/secure_headers/headers/content_security_policy_spec.rb
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Expand Up @@ -56,6 +56,16 @@ module SecureHeaders
expect(csp.value).to eq("default-src *.example.org")
end

it "minifies overlapping port wildcards" do
csp = ContentSecurityPolicy.new(default_src: %w(example.org example.org:* example.org:443 https://example.org:80))
expect(csp.value).to eq("default-src example.org example.org:*")
end

it "allows for port wildcards" do
csp = ContentSecurityPolicy.new(connect_src: %w(ws://localhost:*))
expect(csp.value).to eq("connect-src ws://localhost:*")
end

it "removes http/s schemes from hosts" do
csp = ContentSecurityPolicy.new(default_src: %w(https://example.org))
expect(csp.value).to eq("default-src example.org")
Expand Down Expand Up @@ -102,7 +112,8 @@ module SecureHeaders
end

it "deduplicates any source expressions" do
csp = ContentSecurityPolicy.new(default_src: %w(example.org example.org example.org))
src = %w(example.org example.org http://example.org https://example.org)
csp = ContentSecurityPolicy.new(default_src: src)
expect(csp.value).to eq("default-src example.org")
end

Expand Down