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* [PATCH] httpd: reject requests with spaces in header names
@ 2021-10-19 21:26 Eric Wong
  0 siblings, 0 replies; only message in thread
From: Eric Wong @ 2021-10-19 21:26 UTC (permalink / raw)
  To: meta

Malicious clients may attempt HTTP request smuggling this way.
This doesn't affect our current code as we only look for exact
matches, but it could affect other servers behind a
to-be-implemented reverse proxy built around our -httpd.

This doesn't affect users behind varnish at all, nor the
HTTPS/HTTP reverse proxy I use (I don't know about nginx), but
could be passed through by other reverse proxies.

This change is only needed for HTTP::Parser::XS which most users
probably use.  Users of the pure Perl parser (via
PLACK_HTTP_PARSER_PP=1) already hit 400 errors in this case,
so this makes the common XS case consistent with the pure Perl
case.

cf. https://www.mozilla.org/en-US/security/advisories/mfsa2006-33/
---
 lib/PublicInbox/HTTP.pm | 1 +
 t/httpd-corner.t        | 7 ++++++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/lib/PublicInbox/HTTP.pm b/lib/PublicInbox/HTTP.pm
index 0f4b5047..18a19250 100644
--- a/lib/PublicInbox/HTTP.pm
+++ b/lib/PublicInbox/HTTP.pm
@@ -91,6 +91,7 @@ sub event_step { # called by PublicInbox::DS
 		}
 		$self->do_read($rbuf, 8192, length($$rbuf)) or return;
 	}
+	return quit($self, 400) if grep(/\s/, keys %env); # stop smugglers
 	$$rbuf = substr($$rbuf, $r);
 	my $len = input_prepare($self, \%env) //
 		return write_err($self, undef); # EMFILE/ENFILE
diff --git a/t/httpd-corner.t b/t/httpd-corner.t
index cec754c9..0a613a9e 100644
--- a/t/httpd-corner.t
+++ b/t/httpd-corner.t
@@ -82,7 +82,12 @@ if ('test worker death') {
 	like($body, qr/\A[0-9]+\z/, '/pid response');
 	isnt($body, $pid, 'respawned worker');
 }
-
+{
+	my $conn = conn_for($sock, 'Header spaces bogus');
+	$conn->write("GET /empty HTTP/1.1\r\nSpaced-Out : 3\r\n\r\n");
+	$conn->read(my $buf, 4096);
+	like($buf, qr!\AHTTP/1\.[0-9] 400 !, 'got 400 response on bad request');
+}
 {
 	my $conn = conn_for($sock, 'streaming callback');
 	$conn->write("GET /callback HTTP/1.0\r\n\r\n");

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2021-10-19 21:26 [PATCH] httpd: reject requests with spaces in header names Eric Wong

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