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authorLoïc Hoguin <[email protected]>2013-01-06 19:49:01 +0100
committerLoïc Hoguin <[email protected]>2013-01-06 19:49:01 +0100
commita013becc66b50db038c1f7f3539040b4482bba18 (patch)
tree78b95a24fa5959a89125752b18d6c9ea42a0424f
parent638d0345d1c738a6a4e73ce291f5ca6bfa4d0b5d (diff)
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Add protection against slowloris vulnerability
This changes the behavior of the `timeout` protocol option to mean "Time in which the full request line and headers must be received". The default of 5s should be fine for all normal uses. This change has no noticeable impact on performance and is thus enabled by default for everyone. It can be disabled by setting `timeout` to `infinity` although that is definitely not encouraged. Inspired by the contribution from @naryl on github.
-rw-r--r--src/cowboy_protocol.erl56
-rw-r--r--test/http_SUITE.erl32
2 files changed, 72 insertions, 16 deletions
diff --git a/src/cowboy_protocol.erl b/src/cowboy_protocol.erl
index b82fa2b..48c0b00 100644
--- a/src/cowboy_protocol.erl
+++ b/src/cowboy_protocol.erl
@@ -38,8 +38,8 @@
%% not available at this point.</dd>
%% <dt>onresponse</dt><dd>Optional fun that allows replacing a response
%% sent by the application.</dd>
-%% <dt>timeout</dt><dd>Time in milliseconds before an idle
-%% connection is closed. Defaults to 5000 milliseconds.</dd>
+%% <dt>timeout</dt><dd>Time in milliseconds a client has to send the
+%% full request line and headers. Defaults to 5000 milliseconds.</dd>
%% </dl>
%%
%% Note that there is no need to monitor these processes when using Cowboy as
@@ -74,7 +74,8 @@
max_header_name_length :: non_neg_integer(),
max_header_value_length :: non_neg_integer(),
max_headers :: non_neg_integer(),
- timeout :: timeout()
+ timeout :: timeout(),
+ until :: non_neg_integer() | infinity
}).
%% API.
@@ -116,7 +117,15 @@ init(ListenerPid, Socket, Transport, Opts) ->
max_request_line_length=MaxRequestLineLength,
max_header_name_length=MaxHeaderNameLength,
max_header_value_length=MaxHeaderValueLength, max_headers=MaxHeaders,
- timeout=Timeout, onrequest=OnRequest, onresponse=OnResponse}, 0).
+ onrequest=OnRequest, onresponse=OnResponse,
+ timeout=Timeout, until=until(Timeout)}, 0).
+
+-spec until(timeout()) -> non_neg_integer() | infinity.
+until(infinity) ->
+ infinity;
+until(Timeout) ->
+ {Me, S, Mi} = os:timestamp(),
+ Me * 1000000000 + S * 1000 + Mi div 1000 + Timeout.
%% Request parsing.
%%
@@ -125,10 +134,24 @@ init(ListenerPid, Socket, Transport, Opts) ->
%% right after the header parsing is finished and the code becomes
%% more interesting past that point.
+-spec recv(inet:socket(), module(), non_neg_integer() | infinity)
+ -> {ok, binary()} | {error, closed | timeout | atom()}.
+recv(Socket, Transport, infinity) ->
+ Transport:recv(Socket, 0, infinity);
+recv(Socket, Transport, Until) ->
+ {Me, S, Mi} = os:timestamp(),
+ Now = Me * 1000000000 + S * 1000 + Mi div 1000,
+ Timeout = Until - Now,
+ if Timeout < 0 ->
+ {error, timeout};
+ true ->
+ Transport:recv(Socket, 0, Timeout)
+ end.
+
-spec wait_request(binary(), #state{}, non_neg_integer()) -> ok.
wait_request(Buffer, State=#state{socket=Socket, transport=Transport,
- timeout=Timeout}, ReqEmpty) ->
- case Transport:recv(Socket, 0, Timeout) of
+ until=Until}, ReqEmpty) ->
+ case recv(Socket, Transport, Until) of
{ok, Data} ->
parse_request(<< Buffer/binary, Data/binary >>, State, ReqEmpty);
{error, _} ->
@@ -219,8 +242,8 @@ wait_header(_, State=#state{max_headers=MaxHeaders}, _, _, _, _, _, Headers)
when length(Headers) >= MaxHeaders ->
error_terminate(400, State);
wait_header(Buffer, State=#state{socket=Socket, transport=Transport,
- timeout=Timeout}, M, P, Q, F, V, H) ->
- case Transport:recv(Socket, 0, Timeout) of
+ until=Until}, M, P, Q, F, V, H) ->
+ case recv(Socket, Transport, Until) of
{ok, Data} ->
parse_header(<< Buffer/binary, Data/binary >>,
State, M, P, Q, F, V, H);
@@ -291,9 +314,9 @@ parse_hd_name_ws(<< C, Rest/bits >>, S, M, P, Q, F, V, H, Name) ->
end.
wait_hd_before_value(Buffer, State=#state{
- socket=Socket, transport=Transport, timeout=Timeout},
+ socket=Socket, transport=Transport, until=Until},
M, P, Q, F, V, H, N) ->
- case Transport:recv(Socket, 0, Timeout) of
+ case recv(Socket, Transport, Until) of
{ok, Data} ->
parse_hd_before_value(<< Buffer/binary, Data/binary >>,
State, M, P, Q, F, V, H, N);
@@ -323,9 +346,9 @@ parse_hd_before_value(Buffer, State=#state{
%% to change the other arguments' position and trigger costy
%% operations for no reasons.
wait_hd_value(_, State=#state{
- socket=Socket, transport=Transport, timeout=Timeout},
+ socket=Socket, transport=Transport, until=Until},
M, P, Q, F, V, H, N, SoFar) ->
- case Transport:recv(Socket, 0, Timeout) of
+ case recv(Socket, Transport, Until) of
{ok, Data} ->
parse_hd_value(Data, State, M, P, Q, F, V, H, N, SoFar);
{error, timeout} ->
@@ -338,9 +361,9 @@ wait_hd_value(_, State=#state{
%% to check for multilines allows us to avoid a few tests in
%% the critical path, but forces us to have a special function.
wait_hd_value_nl(_, State=#state{
- socket=Socket, transport=Transport, timeout=Timeout},
+ socket=Socket, transport=Transport, until=Until},
M, P, Q, F, V, Headers, Name, SoFar) ->
- case Transport:recv(Socket, 0, Timeout) of
+ case recv(Socket, Transport, Until) of
{ok, << C, Data/bits >>} when C =:= $\s; C =:= $\t ->
parse_hd_value(Data, State, M, P, Q, F, V, Headers, Name, SoFar);
{ok, Data} ->
@@ -492,7 +515,8 @@ resume(State, Env, Tail, Module, Function, Args) ->
end.
-spec next_request(cowboy_req:req(), #state{}, any()) -> ok.
-next_request(Req, State=#state{req_keepalive=Keepalive}, HandlerRes) ->
+next_request(Req, State=#state{req_keepalive=Keepalive, timeout=Timeout},
+ HandlerRes) ->
cowboy_req:ensure_response(Req, 204),
{BodyRes, [Buffer, Connection]} = case cowboy_req:skip_body(Req) of
{ok, Req2} -> {ok, cowboy_req:get([buffer, connection], Req2)};
@@ -503,7 +527,7 @@ next_request(Req, State=#state{req_keepalive=Keepalive}, HandlerRes) ->
case {HandlerRes, BodyRes, Connection} of
{ok, ok, keepalive} ->
?MODULE:parse_request(Buffer, State#state{
- req_keepalive=Keepalive + 1}, 0);
+ req_keepalive=Keepalive + 1, until=until(Timeout)}, 0);
_Closed ->
terminate(State)
end.
diff --git a/test/http_SUITE.erl b/test/http_SUITE.erl
index 7ce0835..607178f 100644
--- a/test/http_SUITE.erl
+++ b/test/http_SUITE.erl
@@ -60,6 +60,8 @@
-export([set_resp_body/1]).
-export([set_resp_header/1]).
-export([set_resp_overwrite/1]).
+-export([slowloris/1]).
+-export([slowloris2/1]).
-export([static_attribute_etag/1]).
-export([static_function_etag/1]).
-export([static_mimetypes_function/1]).
@@ -110,6 +112,8 @@ groups() ->
set_resp_body,
set_resp_header,
set_resp_overwrite,
+ slowloris,
+ slowloris2,
static_attribute_etag,
static_function_etag,
static_mimetypes_function,
@@ -812,6 +816,34 @@ set_resp_overwrite(Config) ->
{<<"server">>, <<"DesireDrive/1.0">>}
= lists:keyfind(<<"server">>, 1, Headers).
+slowloris(Config) ->
+ Client = ?config(client, Config),
+ Transport = ?config(transport, Config),
+ {ok, Client2} = cowboy_client:connect(
+ Transport, "localhost", ?config(port, Config), Client),
+ try
+ [begin
+ {ok, _} = cowboy_client:raw_request([C], Client2),
+ receive after 25 -> ok end
+ end || C <- "GET / HTTP/1.1\r\nHost: localhost\r\n"
+ "User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US)\r\n"
+ "Cookie: name=aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\r\n\r\n"],
+ error(failure)
+ catch error:{badmatch, _} ->
+ ok
+ end.
+
+slowloris2(Config) ->
+ Client = ?config(client, Config),
+ Transport = ?config(transport, Config),
+ {ok, Client2} = cowboy_client:connect(
+ Transport, "localhost", ?config(port, Config), Client),
+ {ok, _} = cowboy_client:raw_request("GET / HTTP/1.1\r\n", Client2),
+ receive after 300 -> ok end,
+ {ok, _} = cowboy_client:raw_request("Host: localhost\r\n", Client2),
+ receive after 300 -> ok end,
+ {ok, 408, _, _} = cowboy_client:response(Client2).
+
static_attribute_etag(Config) ->
Client = ?config(client, Config),
{ok, Client2} = cowboy_client:request(<<"GET">>,