File 3891-ssh-crypto-Move-undocumented-hash-cmp-func... of Package erlang

Overview Repositories Revisions Requests Users Attributes Meta

File 3891-ssh-crypto-Move-undocumented-hash-cmp-func.patch of Package erlang (Revision 49aa26b943fcbed41dda0b0a8caee5fb)

Currently displaying revision 49aa26b943fcbed41dda0b0a8caee5fb , Show latest

From d22f8d77a240abe8f13b5f43aa224b89df383bc2 Mon Sep 17 00:00:00 2001
From: Hans Nilsson <hans@erlang.org>
Date: Wed, 21 Apr 2021 09:02:12 +0200
Subject: [PATCH] ssh,crypto: Move undocumented hash cmp func

to the only otp user ssh.
---
 lib/crypto/src/crypto.erl     | 30 ------------------------------
 lib/ssh/doc/src/ssh.xml       |  7 +++++++
 lib/ssh/src/ssh_auth.erl      |  2 +-
 lib/ssh/src/ssh_lib.erl       | 26 ++++++++++++++++++++++++--
 lib/ssh/src/ssh_transport.erl |  4 ++--
 5 files changed, 34 insertions(+), 35 deletions(-)

diff --git a/lib/crypto/src/crypto.erl b/lib/crypto/src/crypto.erl
index 81154e0884..eefa2a4fb1 100644
--- a/lib/crypto/src/crypto.erl
+++ b/lib/crypto/src/crypto.erl
@@ -24,7 +24,6 @@
 
 -export([start/0, stop/0, info_lib/0, info_fips/0, supports/0, enable_fips_mode/1,
          version/0, bytes_to_integer/1]).
--export([equal_const_time/2]).
 -export([cipher_info/1, hash_info/1]).
 -export([hash/2, hash_init/1, hash_update/2, hash_final/1]).
 -export([sign/4, sign/5, verify/5, verify/6]).
@@ -725,35 +724,6 @@ enable_fips_mode(Enable) ->
 
 enable_fips_mode_nif(_) -> ?nif_stub.
 
-%%%================================================================
-%%%
-%%% Compare in constant time
-%%%
-%%%================================================================
-
-%%% Candidate for a NIF
-
-equal_const_time(X1, X2) ->
-    equal_const_time(X1, X2, true).
-
-
-equal_const_time(<<B1,R1/binary>>, <<B2,R2/binary>>, Truth) ->
-    equal_const_time(R1, R2, Truth and (B1 == B2));
-equal_const_time(<<_,R1/binary>>, <<>>, Truth) ->
-    equal_const_time(R1, <<>>, Truth and false);
-equal_const_time(<<>>, <<>>, Truth) ->
-    Truth;
-
-equal_const_time([H1|T1], [H2|T2], Truth) ->
-    equal_const_time(T1, T2, Truth and (H1 == H2));
-equal_const_time([_|T1], [], Truth) ->
-    equal_const_time(T1, [], Truth and false);
-equal_const_time([], [], Truth) ->
-    Truth;
-
-equal_const_time(_, _, _) ->
-    false.
-
 -spec pbkdf2_hmac(Digest, Pass, Salt, Iter, KeyLen) -> Result
           when Digest :: sha | sha224 | sha256 | sha384 | sha512,
                Pass :: binary(),
diff --git a/lib/ssh/doc/src/ssh.xml b/lib/ssh/doc/src/ssh.xml
index b88bdc1667..6a8bde4ede 100644
--- a/lib/ssh/doc/src/ssh.xml
+++ b/lib/ssh/doc/src/ssh.xml
@@ -563,6 +563,13 @@
 	    to connect to the server and public key user-authentication fails. The option provides
 	    a list of valid usernames and the corresponding passwords.
 	    </p>
+	    <warning>
+	      <p>Note that this is very insecure due to the plain-text passwords;
+	      it is intended for test purposes.
+	      Use the <seeerl marker="#option-pwdfun"><c>pwdfun</c></seeerl> option
+	      to handle the password checking instead.
+	      </p>
+	    </warning>
           </item>
 
 	  <tag><marker id="option-pk_check_user"/><c>pk_check_user</c></tag>
diff --git a/lib/ssh/src/ssh_auth.erl b/lib/ssh/src/ssh_auth.erl
index fd0ca11e6e..8e32b2d7fc 100644
--- a/lib/ssh/src/ssh_auth.erl
+++ b/lib/ssh/src/ssh_auth.erl
@@ -504,7 +504,7 @@ check_password(User, Password, #ssh{opts=Opts} = Ssh) ->
 
 	undefined ->
 	    Static = get_password_option(Opts, User),
-	    {crypto:equal_const_time(Password,Static), Ssh};
+	    {ssh_lib:comp(Password,Static), Ssh};
 
 	Checker when is_function(Checker,2) ->
 	    {Checker(User, Password), Ssh};
diff --git a/lib/ssh/src/ssh_lib.erl b/lib/ssh/src/ssh_lib.erl
index edfd1bb8a5..1d3b328b05 100644
--- a/lib/ssh/src/ssh_lib.erl
+++ b/lib/ssh/src/ssh_lib.erl
@@ -27,7 +27,8 @@
 -export([
          format_address_port/2, format_address_port/1,
          format_address/1,
-         format_time_ms/1
+         format_time_ms/1,
+         comp/2
         ]).
 
 %%%----------------------------------------------------------------
@@ -59,4 +60,25 @@ format_time_ms(T) when is_integer(T) ->
     end.
 
             
-            
+%%%----------------------------------------------------------------
+
+comp(X1, X2) ->
+    comp(X1, X2, true).
+
+%%% yes - very far from best implementation
+comp(<<B1,R1/binary>>, <<B2,R2/binary>>, Truth) ->
+    comp(R1, R2, Truth and (B1 == B2));
+comp(<<_,R1/binary>>, <<>>, Truth) ->
+    comp(R1, <<>>, Truth and false);
+comp(<<>>, <<>>, Truth) ->
+    Truth;
+
+comp([H1|T1], [H2|T2], Truth) ->
+    comp(T1, T2, Truth and (H1 == H2));
+comp([_|T1], [], Truth) ->
+    comp(T1, [], Truth and false);
+comp([], [], Truth) ->
+    Truth;
+
+comp(_, _, _) ->
+    false.
diff --git a/lib/ssh/src/ssh_transport.erl b/lib/ssh/src/ssh_transport.erl
index 65d695ecb1..74461fb156 100644
--- a/lib/ssh/src/ssh_transport.erl
+++ b/lib/ssh/src/ssh_transport.erl
@@ -284,7 +284,7 @@ is_valid_mac(_, _ , #ssh{recv_mac_size = 0}) ->
     true;
 is_valid_mac(Mac, Data, #ssh{recv_mac = Algorithm,
 			     recv_mac_key = Key, recv_sequence = SeqNum}) ->
-    crypto:equal_const_time(Mac, mac(Algorithm, Key, SeqNum, Data)).
+    ssh_lib:comp(Mac, mac(Algorithm, Key, SeqNum, Data)).
 
 handle_hello_version(Version) ->
     try
@@ -1734,7 +1734,7 @@ decrypt(#ssh{decrypt = 'chacha20-poly1305@openssh.com',
             %% The length is already decrypted and used to divide the input
             %% Check the mac (important that it is timing-safe):
             PolyKey = crypto:crypto_one_time(chacha20, K2, <<0:8/unit:8,Seq:8/unit:8>>, <<0:32/unit:8>>, false),
-            case crypto:equal_const_time(Ctag, crypto:mac(poly1305, PolyKey, <<AAD/binary,Ctext/binary>>)) of
+            case ssh_lib:comp(Ctag, crypto:mac(poly1305, PolyKey, <<AAD/binary,Ctext/binary>>)) of
                 true ->
                     %% MAC is ok, decode
                     IV2 = <<1:8/little-unit:8, Seq:8/unit:8>>,
-- 
2.26.2

Places

File 3891-ssh-crypto-Move-undocumented-hash-cmp-func.patch of Package erlang (Revision 49aa26b943fcbed41dda0b0a8caee5fb)

Places