Wed, 03 Aug 2022 03:04:17 +0200
util.sasl.scram: Refactor channel binding
This will ease support for new channel binding methods.
355 | 1 | |
2 | local base64, unbase64 = require "mime".b64, require"mime".unb64; | |
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3 | local hashes = require"util.hashes"; |
355 | 4 | local bit = require"bit"; |
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util.sasl.scram: Use the new util.hashes and util.random
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5 | local random = require"util.random"; |
355 | 6 | |
7 | local tonumber = tonumber; | |
8 | local char, byte = string.char, string.byte; | |
9 | local gsub = string.gsub; | |
10 | local xor = bit.bxor; | |
11 | ||
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plugins.sasl: Alter mechanism loading and pass name of loaded mechanism. Fixes attempting SCRAM-PLUS when only SCRAM is offered
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12 | local function XOR(a, b) |
355 | 13 | return (gsub(a, "()(.)", function(i, c) |
14 | return char(xor(byte(c), byte(b, i))) | |
15 | end)); | |
16 | end | |
17 | ||
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util.sasl.scram: Use the new util.hashes and util.random
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18 | local H, HMAC = hashes.sha1, hashes.hmac_sha1; |
355 | 19 | |
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plugins.sasl: Alter mechanism loading and pass name of loaded mechanism. Fixes attempting SCRAM-PLUS when only SCRAM is offered
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20 | local function Hi(str, salt, i) |
355 | 21 | local U = HMAC(str, salt .. "\0\0\0\1"); |
22 | local ret = U; | |
23 | for _ = 2, i do | |
24 | U = HMAC(str, U); | |
25 | ret = XOR(ret, U); | |
26 | end | |
27 | return ret; | |
28 | end | |
29 | ||
30 | local function Normalize(str) | |
31 | return str; -- TODO | |
32 | end | |
33 | ||
34 | local function value_safe(str) | |
35 | return (gsub(str, "[,=]", { [","] = "=2C", ["="] = "=3D" })); | |
36 | end | |
37 | ||
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38 | local function cb(conn) |
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39 | if conn:ssl() then |
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40 | if sock.getfinished then |
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41 | return "p=tls-unique", sock:getfinished(); |
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42 | end |
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43 | end |
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44 | end |
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45 | |
355 | 46 | local function scram(stream, name) |
47 | local username = "n=" .. value_safe(stream.username); | |
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48 | local c_nonce = base64(random.bytes(15)); |
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49 | local our_nonce = "r=" .. c_nonce; |
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50 | local client_first_message_bare = username .. "," .. our_nonce; |
355 | 51 | local cbind_data = ""; |
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52 | local gs2_cbind_flag = "n"; |
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SCRAM: Add channel binding support (SCRAM-SHA-1-PLUS)
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53 | if name == "SCRAM-SHA-1-PLUS" then |
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54 | gs2_cbind_flag, cbind_data = cb(stream.conn); |
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55 | elseif cb(stream.conn) then |
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56 | gs2_cbind_flag = "y"; |
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SCRAM: Add channel binding support (SCRAM-SHA-1-PLUS)
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57 | end |
355 | 58 | local gs2_header = gs2_cbind_flag .. ",,"; |
59 | local client_first_message = gs2_header .. client_first_message_bare; | |
60 | local cont, server_first_message = coroutine.yield(client_first_message); | |
61 | if cont ~= "challenge" then return false end | |
62 | ||
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util.sasl.scram: Correctly verify that the server added its own nonce
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63 | local nonce, salt, iteration_count = server_first_message:match("(r=[^,]+),s=([^,]*),i=(%d+)"); |
355 | 64 | local i = tonumber(iteration_count); |
65 | salt = unbase64(salt); | |
66 | if not nonce or not salt or not i then | |
67 | return false, "Could not parse server_first_message"; | |
68 | elseif nonce:find(c_nonce, 3, true) ~= 3 then | |
69 | return false, "nonce sent by server does not match our nonce"; | |
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util.sasl.scram: Correctly verify that the server added its own nonce
Kim Alvefur <zash@zash.se>
parents:
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70 | elseif nonce == our_nonce then |
355 | 71 | return false, "server did not append s-nonce to nonce"; |
72 | end | |
73 | ||
74 | local cbind_input = gs2_header .. cbind_data; | |
75 | local channel_binding = "c=" .. base64(cbind_input); | |
76 | local client_final_message_without_proof = channel_binding .. "," .. nonce; | |
77 | ||
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util.sasl.scram: Add support for authenticating with pre-hashed password
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78 | local SaltedPassword; |
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79 | local ClientKey; |
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80 | local ServerKey; |
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81 | |
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82 | if stream.client_key and stream.server_key then |
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83 | ClientKey = stream.client_key; |
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84 | ServerKey = stream.server_key; |
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85 | else |
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86 | if stream.salted_password then |
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87 | SaltedPassword = stream.salted_password; |
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88 | elseif stream.password then |
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89 | SaltedPassword = Hi(Normalize(stream.password), salt, i); |
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90 | end |
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91 | ServerKey = HMAC(SaltedPassword, "Server Key"); |
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92 | ClientKey = HMAC(SaltedPassword, "Client Key"); |
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93 | end |
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94 | |
355 | 95 | local StoredKey = H(ClientKey); |
96 | local AuthMessage = client_first_message_bare .. "," .. server_first_message .. "," .. client_final_message_without_proof; | |
97 | local ClientSignature = HMAC(StoredKey, AuthMessage); | |
98 | local ClientProof = XOR(ClientKey, ClientSignature); | |
99 | local ServerSignature = HMAC(ServerKey, AuthMessage); | |
100 | ||
101 | local proof = "p=" .. base64(ClientProof); | |
102 | local client_final_message = client_final_message_without_proof .. "," .. proof; | |
103 | ||
104 | local ok, server_final_message = coroutine.yield(client_final_message); | |
105 | if ok ~= "success" then return false, "success-expected" end | |
106 | ||
107 | local verifier = server_final_message:match("v=([^,]+)"); | |
108 | if unbase64(verifier) ~= ServerSignature then | |
109 | return false, "server signature did not match"; | |
110 | end | |
111 | return true; | |
112 | end | |
113 | ||
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plugins.sasl: Alter mechanism loading and pass name of loaded mechanism. Fixes attempting SCRAM-PLUS when only SCRAM is offered
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114 | return function (stream, name) |
355 | 115 | if stream.username and (stream.password or (stream.client_key or stream.server_key)) then |
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plugins.sasl: Alter mechanism loading and pass name of loaded mechanism. Fixes attempting SCRAM-PLUS when only SCRAM is offered
Kim Alvefur <zash@zash.se>
parents:
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116 | if name == "SCRAM-SHA-1" then |
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plugins.sasl: Alter mechanism loading and pass name of loaded mechanism. Fixes attempting SCRAM-PLUS when only SCRAM is offered
Kim Alvefur <zash@zash.se>
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117 | return scram, 99; |
359 | 118 | elseif name == "SCRAM-SHA-1-PLUS" then |
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119 | if cb(stream.conn) then |
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plugins.sasl: Alter mechanism loading and pass name of loaded mechanism. Fixes attempting SCRAM-PLUS when only SCRAM is offered
Kim Alvefur <zash@zash.se>
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120 | return scram, 100; |
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plugins.sasl: Alter mechanism loading and pass name of loaded mechanism. Fixes attempting SCRAM-PLUS when only SCRAM is offered
Kim Alvefur <zash@zash.se>
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121 | end |
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122 | end |
355 | 123 | end |
124 | end | |
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125 |