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Merge pull request 'MRF: match domain rules literally' (#8046) from lambadalambda/pleroma:fix/mrf-domain-regex-escape into develop

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Reviewed-on: https://git.pleroma.social/pleroma/pleroma/pulls/8046
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lain 2026-10-31 16:18:35 +00:00
commit 0157ade4d3
3 changed files with 27 additions and 20 deletions
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1
changelog.d/mrf-domain-regex-escape.security Normal file
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@ -0,0 +1 @@
MRF domain rules now match dots literally, so a rule for `good.example` no longer also matches `goodxexample`, and wildcard rules no longer backtrack on hostile host names

15
lib/pleroma/web/activity_pub/mrf.ex
View file

@ -148,14 +148,13 @@ defmodule Pleroma.Web.ActivityPub.MRF do
@spec subdomains_regex([String.t()]) :: [Regex.t()]
def subdomains_regex(domains) when is_list(domains) do
for domain <- domains do
try do
target = String.replace(domain, "*.", "(.*\\.)*")
~r<^#{target}$>i
rescue
e ->
Logger.error("MRF: Invalid subdomain Regex: #{domain}")
reraise e, __STACKTRACE__
end
{prefix, rest} =
case domain do
"*." <> rest -> {"(.*\\.)?", rest}
_ -> {"", domain}
end
~r<^#{prefix}#{Regex.escape(rest)}$>i
end
end

31
test/pleroma/web/activity_pub/mrf_test.exs
View file

@ -6,8 +6,6 @@ defmodule Pleroma.Web.ActivityPub.MRFTest do
use ExUnit.Case
use Pleroma.Tests.Helpers
import ExUnit.CaptureLog
alias Pleroma.Web.ActivityPub.MRF
defp regexes_match!([], []), do: true
@ -21,14 +19,14 @@ defmodule Pleroma.Web.ActivityPub.MRFTest do
test "subdomains_regex/1" do
regexes = MRF.subdomains_regex(["unsafe.tld", "*.unsafe.tld"])
assert regexes_match!(regexes, [~r/^unsafe.tld$/i, ~r/^(.*\.)*unsafe.tld$/i])
assert regexes_match!(regexes, [~r/^unsafe\.tld$/i, ~r/^(.*\.)?unsafe\.tld$/i])
end
describe "subdomain_match/2" do
test "common domains" do
regexes = MRF.subdomains_regex(["unsafe.tld", "unsafe2.tld"])
assert regexes_match!(regexes, [~r/^unsafe.tld$/i, ~r/^unsafe2.tld$/i])
assert regexes_match!(regexes, [~r/^unsafe\.tld$/i, ~r/^unsafe2\.tld$/i])
assert MRF.subdomain_match?(regexes, "unsafe.tld")
assert MRF.subdomain_match?(regexes, "unsafe2.tld")
@ -39,7 +37,7 @@ defmodule Pleroma.Web.ActivityPub.MRFTest do
test "wildcard domains with one subdomain" do
regexes = MRF.subdomains_regex(["*.unsafe.tld"])
assert regexes_match!(regexes, [~r/^(.*\.)*unsafe.tld$/i])
assert regexes_match!(regexes, [~r/^(.*\.)?unsafe\.tld$/i])
assert MRF.subdomain_match?(regexes, "unsafe.tld")
assert MRF.subdomain_match?(regexes, "sub.unsafe.tld")
@ -50,7 +48,7 @@ defmodule Pleroma.Web.ActivityPub.MRFTest do
test "wildcard domains with two subdomains" do
regexes = MRF.subdomains_regex(["*.unsafe.tld"])
assert regexes_match!(regexes, [~r/^(.*\.)*unsafe.tld$/i])
assert regexes_match!(regexes, [~r/^(.*\.)?unsafe\.tld$/i])
assert MRF.subdomain_match?(regexes, "unsafe.tld")
assert MRF.subdomain_match?(regexes, "sub.sub.unsafe.tld")
@ -61,7 +59,7 @@ defmodule Pleroma.Web.ActivityPub.MRFTest do
test "matches are case-insensitive" do
regexes = MRF.subdomains_regex(["UnSafe.TLD", "UnSAFE2.Tld"])
assert regexes_match!(regexes, [~r/^UnSafe.TLD$/i, ~r/^UnSAFE2.Tld$/i])
assert regexes_match!(regexes, [~r/^UnSafe\.TLD$/i, ~r/^UnSAFE2\.Tld$/i])
assert MRF.subdomain_match?(regexes, "UNSAFE.TLD")
assert MRF.subdomain_match?(regexes, "UNSAFE2.TLD")
@ -72,11 +70,20 @@ defmodule Pleroma.Web.ActivityPub.MRFTest do
refute MRF.subdomain_match?(regexes, "example.com")
end
test "logs sensible error on accidental wildcard" do
assert_raise Regex.CompileError, fn ->
assert capture_log(MRF.subdomains_regex(["*unsafe.tld"])) =~
"MRF: Invalid subdomain Regex: *unsafe.tld"
end
test "dots only match dots" do
regexes = MRF.subdomains_regex(["unsafe.tld", "*.other.tld"])
refute MRF.subdomain_match?(regexes, "unsafextld")
refute MRF.subdomain_match?(regexes, "otherxtld")
refute MRF.subdomain_match?(regexes, "sub.otherxtld")
end
test "accidental wildcards and regex syntax match nothing" do
regexes = MRF.subdomains_regex(["*unsafe.tld", "bad(.tld"])
refute MRF.subdomain_match?(regexes, "unsafe.tld")
refute MRF.subdomain_match?(regexes, "sub.unsafe.tld")
refute MRF.subdomain_match?(regexes, "bad.tld")
end
end