From e33d2a7b3041d7f8cd1f0a2a4ca42a5bc112b14e Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Mon, 31 Aug 2020 18:16:45 +0300 Subject: SUNRPC: remove RC4-HMAC-MD5 support from KerberosV The RC4-HMAC-MD5 KerberosV algorithm is based on RFC 4757 [0], which was specifically issued for interoperability with Windows 2000, but was never intended to receive the same level of support. The RFC says The IETF Kerberos community supports publishing this specification as an informational document in order to describe this widely implemented technology. However, while these encryption types provide the operations necessary to implement the base Kerberos specification [RFC4120], they do not provide all the required operations in the Kerberos cryptography framework [RFC3961]. As a result, it is not generally possible to implement potential extensions to Kerberos using these encryption types. The Kerberos encryption type negotiation mechanism [RFC4537] provides one approach for using such extensions even when a Kerberos infrastructure uses long-term RC4 keys. Because this specification does not implement operations required by RFC 3961 and because of security concerns with the use of RC4 and MD4 discussed in Section 8, this specification is not appropriate for publication on the standards track. The RC4-HMAC encryption types are used to ease upgrade of existing Windows NT environments, provide strong cryptography (128-bit key lengths), and provide exportable (meet United States government export restriction requirements) encryption. This document describes the implementation of those encryption types. Furthermore, this RFC was re-classified as 'historic' by RFC 8429 [1] in 2018, stating that 'none of the encryption types it specifies should be used' Note that other outdated algorithms are left in place (some of which are guarded by CONFIG_SUNRPC_DISABLE_INSECURE_ENCTYPES), so this should only adversely affect interoperability with Windows NT/2000 systems that have not received any updates since 2008 (but are connected to a network nonetheless) [0] https://tools.ietf.org/html/rfc4757 [1] https://tools.ietf.org/html/rfc8429 Signed-off-by: Ard Biesheuvel Acked-by: J. Bruce Fields Signed-off-by: Herbert Xu --- net/sunrpc/Kconfig | 1 - 1 file changed, 1 deletion(-) (limited to 'net/sunrpc/Kconfig') diff --git a/net/sunrpc/Kconfig b/net/sunrpc/Kconfig index 3bcf985507be..bbbb5af0af13 100644 --- a/net/sunrpc/Kconfig +++ b/net/sunrpc/Kconfig @@ -21,7 +21,6 @@ config RPCSEC_GSS_KRB5 depends on SUNRPC && CRYPTO depends on CRYPTO_MD5 && CRYPTO_DES && CRYPTO_CBC && CRYPTO_CTS depends on CRYPTO_ECB && CRYPTO_HMAC && CRYPTO_SHA1 && CRYPTO_AES - depends on CRYPTO_ARC4 default y select SUNRPC_GSS help -- cgit v1.2.3