[pkg-wpa-devel] Bug#649202: wpasupplicant does not correctly handle non-ASCII passwords for MS-CHAP, MS-CHAPv2
Evan Broder
evan at ebroder.net
Fri Nov 18 19:29:00 UTC 2011
Package: wpasupplicant
Version: 0.7.3-5
Severity: wishlist
Tags: patch
Debian's current version of wpasupplicant treats the password provided
for MS-CHAP and MS-CHAPv2 as ASCII, converting it to the RFC-required
UCS-2 by inserting NULL between each byte.
Obviously, this means that the password can't contain non-ASCII
characters, in spite of that being allowed by the spec.
I submitted a patch for this to wpasupplicant upstream, which was
accepted as c48183fca2d32cd45763fdbf45144aac856bea93 (attached). I
would appreciate it if tihs patch could be included in Debian's
wpasupplicant package.
Thanks
-- System Information:
Debian Release: wheezy/sid
APT prefers oneiric-updates
APT policy: (500, 'oneiric-updates'), (500, 'oneiric-security'), (500, 'oneiric'), (100, 'oneiric-backports')
Architecture: amd64 (x86_64)
Kernel: Linux 3.0.0-12-generic (SMP w/4 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Versions of packages wpasupplicant depends on:
ii adduser 3.112+nmu1ubuntu5 add and remove users and groups
ii libc6 2.13-20ubuntu5 Embedded GNU C Library: Shared lib
ii libdbus-1-3 1.4.14-1ubuntu1 simple interprocess messaging syst
ii libnl3 3.0-1.1ubuntu1 library for dealing with netlink s
ii libpcsclite1 1.7.2-2ubuntu2 Middleware to access a smart card
ii libreadline6 6.2-2ubuntu1 GNU readline and history libraries
ii libssl1.0.0 1.0.0e-2ubuntu4 SSL shared libraries
ii lsb-base 4.0-0ubuntu16 Linux Standard Base 4.0 init scrip
wpasupplicant recommends no packages.
Versions of packages wpasupplicant suggests:
pn libengine-pkcs11-openssl <none> (no description available)
pn wpagui <none> (no description available)
-- no debconf information
-------------- next part --------------
>From c48183fca2d32cd45763fdbf45144aac856bea93 Mon Sep 17 00:00:00 2001
From: Evan Broder <ebroder at mokafive.com>
Date: Sat, 29 Oct 2011 00:23:54 +0300
Subject: [PATCH] For MS-CHAP, convert the password from UTF-8 to UCS-2
The MS-CHAPv1 and MS-CHAPv2 RFCs specify that the password is a string
of "Unicode characters", which for Windows means UCS-2; thus the
password could be any even-length string of up to 512 bytes.
Instead of making the incompatible change of requiring the incoming
password to be UCS-2 encoded, assume the password is UTF-8 encoded and
convert it before using it in NtPasswordHash and
EncryptPwBlockWithPasswordHash.
Signed-off-by: Evan Broder <ebroder at mokafive.com>
---
src/crypto/ms_funcs.c | 106 +++++++++++++++++++++++++++++++++++++------------
1 files changed, 80 insertions(+), 26 deletions(-)
diff --git a/src/crypto/ms_funcs.c b/src/crypto/ms_funcs.c
index dae15ab..c439ae9 100644
--- a/src/crypto/ms_funcs.c
+++ b/src/crypto/ms_funcs.c
@@ -19,6 +19,60 @@
#include "ms_funcs.h"
#include "crypto.h"
+/**
+ * utf8_to_ucs2 - Convert UTF-8 string to UCS-2 encoding
+ * @utf8_string: UTF-8 string (IN)
+ * @utf8_string_len: Length of utf8_string (IN)
+ * @ucs2_buffer: UCS-2 buffer (OUT)
+ * @ucs2_buffer_size: Length of UCS-2 buffer (IN)
+ * @ucs2_string_size: Number of 2-byte words in the resulting UCS-2 string
+ * Returns: 0 on success, -1 on failure
+ */
+static int utf8_to_ucs2(const u8 *utf8_string, size_t utf8_string_len,
+ u8 *ucs2_buffer, size_t ucs2_buffer_size,
+ size_t *ucs2_string_size)
+{
+ size_t i, j;
+
+ for (i = 0, j = 0; i < utf8_string_len; i++) {
+ u8 c = utf8_string[i];
+ if (j >= ucs2_buffer_size) {
+ /* input too long */
+ return -1;
+ }
+ if (c <= 0x7F) {
+ WPA_PUT_LE16(ucs2_buffer + j, c);
+ j += 2;
+ } else if (i == utf8_string_len - 1 ||
+ j >= ucs2_buffer_size - 1) {
+ /* incomplete surrogate */
+ return -1;
+ } else {
+ u8 c2 = utf8_string[++i];
+ if ((c & 0xE0) == 0xC0) {
+ /* two-byte encoding */
+ WPA_PUT_LE16(ucs2_buffer + j,
+ ((c & 0x1F) << 6) | (c2 & 0x3F));
+ j += 2;
+ } else if (i == utf8_string_len ||
+ j >= ucs2_buffer_size - 1) {
+ /* incomplete surrogate */
+ return -1;
+ } else {
+ /* three-byte encoding */
+ u8 c3 = utf8_string[++i];
+ WPA_PUT_LE16(ucs2_buffer + j,
+ ((c & 0xF) << 12) |
+ ((c2 & 0x3F) << 6) | (c3 & 0x3F));
+ }
+ }
+ }
+
+ if (ucs2_string_size)
+ *ucs2_string_size = j / 2;
+ return 0;
+}
+
/**
* challenge_hash - ChallengeHash() - RFC 2759, Sect. 8.2
@@ -53,7 +107,7 @@ static int challenge_hash(const u8 *peer_challenge, const u8 *auth_challenge,
/**
* nt_password_hash - NtPasswordHash() - RFC 2759, Sect. 8.3
- * @password: 0-to-256-unicode-char Password (IN; ASCII)
+ * @password: 0-to-256-unicode-char Password (IN; UTF-8)
* @password_len: Length of password
* @password_hash: 16-octet PasswordHash (OUT)
* Returns: 0 on success, -1 on failure
@@ -62,18 +116,13 @@ int nt_password_hash(const u8 *password, size_t password_len,
u8 *password_hash)
{
u8 buf[512], *pos;
- size_t i, len;
+ size_t len, max_len;
- if (password_len > 256)
- password_len = 256;
-
- /* Convert password into unicode */
- for (i = 0; i < password_len; i++) {
- buf[2 * i] = password[i];
- buf[2 * i + 1] = 0;
- }
+ max_len = sizeof(buf);
+ if (utf8_to_ucs2(password, password_len, buf, max_len, &len) < 0)
+ return -1;
- len = password_len * 2;
+ len *= 2;
pos = buf;
return md4_vector(1, (const u8 **) &pos, &len, password_hash);
}
@@ -117,7 +166,7 @@ void challenge_response(const u8 *challenge, const u8 *password_hash,
* @peer_challenge: 16-octet PeerChallenge (IN)
* @username: 0-to-256-char UserName (IN)
* @username_len: Length of username
- * @password: 0-to-256-unicode-char Password (IN; ASCII)
+ * @password: 0-to-256-unicode-char Password (IN; UTF-8)
* @password_len: Length of password
* @response: 24-octet Response (OUT)
* Returns: 0 on success, -1 on failure
@@ -225,7 +274,7 @@ int generate_authenticator_response_pwhash(
/**
* generate_authenticator_response - GenerateAuthenticatorResponse() - RFC 2759, Sect. 8.7
- * @password: 0-to-256-unicode-char Password (IN; ASCII)
+ * @password: 0-to-256-unicode-char Password (IN; UTF-8)
* @password_len: Length of password
* @nt_response: 24-octet NT-Response (IN)
* @peer_challenge: 16-octet PeerChallenge (IN)
@@ -254,7 +303,7 @@ int generate_authenticator_response(const u8 *password, size_t password_len,
/**
* nt_challenge_response - NtChallengeResponse() - RFC 2433, Sect. A.5
* @challenge: 8-octet Challenge (IN)
- * @password: 0-to-256-unicode-char Password (IN; ASCII)
+ * @password: 0-to-256-unicode-char Password (IN; UTF-8)
* @password_len: Length of password
* @response: 24-octet Response (OUT)
* Returns: 0 on success, -1 on failure
@@ -375,7 +424,7 @@ int get_asymetric_start_key(const u8 *master_key, u8 *session_key,
/**
* encrypt_pw_block_with_password_hash - EncryptPwBlockWithPasswordHash() - RFC 2759, Sect. 8.10
- * @password: 0-to-256-unicode-char Password (IN; ASCII)
+ * @password: 0-to-256-unicode-char Password (IN; UTF-8)
* @password_len: Length of password
* @password_hash: 16-octet PasswordHash (IN)
* @pw_block: 516-byte PwBlock (OUT)
@@ -385,18 +434,23 @@ int encrypt_pw_block_with_password_hash(
const u8 *password, size_t password_len,
const u8 *password_hash, u8 *pw_block)
{
- size_t i, offset;
+ size_t ucs2_len, offset;
u8 *pos;
- if (password_len > 256)
+ os_memset(pw_block, 0, PWBLOCK_LEN);
+
+ if (utf8_to_ucs2(password, password_len, pw_block, 512, &ucs2_len) < 0)
return -1;
- os_memset(pw_block, 0, PWBLOCK_LEN);
- offset = (256 - password_len) * 2;
- if (os_get_random(pw_block, offset) < 0)
+ if (ucs2_len > 256)
return -1;
- for (i = 0; i < password_len; i++)
- pw_block[offset + i * 2] = password[i];
+
+ offset = (256 - ucs2_len) * 2;
+ if (offset != 0) {
+ os_memmove(pw_block + offset, pw_block, ucs2_len * 2);
+ if (os_get_random(pw_block, offset) < 0)
+ return -1;
+ }
/*
* PasswordLength is 4 octets, but since the maximum password length is
* 256, only first two (in little endian byte order) can be non-zero.
@@ -410,9 +464,9 @@ int encrypt_pw_block_with_password_hash(
/**
* new_password_encrypted_with_old_nt_password_hash - NewPasswordEncryptedWithOldNtPasswordHash() - RFC 2759, Sect. 8.9
- * @new_password: 0-to-256-unicode-char NewPassword (IN; ASCII)
+ * @new_password: 0-to-256-unicode-char NewPassword (IN; UTF-8)
* @new_password_len: Length of new_password
- * @old_password: 0-to-256-unicode-char OldPassword (IN; ASCII)
+ * @old_password: 0-to-256-unicode-char OldPassword (IN; UTF-8)
* @old_password_len: Length of old_password
* @encrypted_pw_block: 516-octet EncryptedPwBlock (OUT)
* Returns: 0 on success, -1 on failure
@@ -450,9 +504,9 @@ void nt_password_hash_encrypted_with_block(const u8 *password_hash,
/**
* old_nt_password_hash_encrypted_with_new_nt_password_hash - OldNtPasswordHashEncryptedWithNewNtPasswordHash() - RFC 2759, Sect. 8.12
- * @new_password: 0-to-256-unicode-char NewPassword (IN; ASCII)
+ * @new_password: 0-to-256-unicode-char NewPassword (IN; UTF-8)
* @new_password_len: Length of new_password
- * @old_password: 0-to-256-unicode-char OldPassword (IN; ASCII)
+ * @old_password: 0-to-256-unicode-char OldPassword (IN; UTF-8)
* @old_password_len: Length of old_password
* @encrypted_password_hash: 16-octet EncryptedPasswordHash (OUT)
* Returns: 0 on success, -1 on failure
--
1.7.5.4
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