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Commit fe9a2705 authored by Chuck Lever's avatar Chuck Lever Committed by Anna Schumaker
Browse files

SUNRPC: Add build option to disable support for insecure enctypes 



Enable distributions to enforce the rejection of ancient and
insecure Kerberos enctypes in the kernel's RPCSEC_GSS
implementation. These are the single-DES encryption types that
were deprecated in 2012 by RFC 6649.

Enctypes that were deprecated more recently (by RFC 8429) remain
fully supported for now because they are still likely to be widely
used.

Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
Acked-by: default avatarSimo Sorce <simo@redhat.com>
Signed-off-by: default avatarAnna Schumaker <Anna.Schumaker@Netapp.com>
parent 067fb11b

include/linux/sunrpc/gss_krb5_enctypes.h

+41 −1
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

/*

 * Dumb way to share this static piece of information with nfsd

 * Define the string that exports the set of kernel-supported

 * Kerberos enctypes. This list is sent via upcall to gssd, and

 * is also exposed via the nfsd /proc API. The consumers generally

 * treat this as an ordered list, where the first item in the list

 * is the most preferred.

 */



#ifndef _LINUX_SUNRPC_GSS_KRB5_ENCTYPES_H

#define _LINUX_SUNRPC_GSS_KRB5_ENCTYPES_H



#ifdef CONFIG_SUNRPC_DISABLE_INSECURE_ENCTYPES



/*

 * NB: This list includes encryption types that were deprecated

 * by RFC 8429 (DES3_CBC_SHA1 and ARCFOUR_HMAC).

 *

 * ENCTYPE_AES256_CTS_HMAC_SHA1_96

 * ENCTYPE_AES128_CTS_HMAC_SHA1_96

 * ENCTYPE_DES3_CBC_SHA1

 * ENCTYPE_ARCFOUR_HMAC

 */

#define KRB5_SUPPORTED_ENCTYPES "18,17,16,23"



#else	/* CONFIG_SUNRPC_DISABLE_INSECURE_ENCTYPES */



/*

 * NB: This list includes encryption types that were deprecated

 * by RFC 8429 and RFC 6649.

 *

 * ENCTYPE_AES256_CTS_HMAC_SHA1_96

 * ENCTYPE_AES128_CTS_HMAC_SHA1_96

 * ENCTYPE_DES3_CBC_SHA1

 * ENCTYPE_ARCFOUR_HMAC

 * ENCTYPE_DES_CBC_MD5

 * ENCTYPE_DES_CBC_CRC

 * ENCTYPE_DES_CBC_MD4

 */

#define KRB5_SUPPORTED_ENCTYPES "18,17,16,23,3,1,2"



#endif	/* CONFIG_SUNRPC_DISABLE_INSECURE_ENCTYPES */



#endif	/* _LINUX_SUNRPC_GSS_KRB5_ENCTYPES_H */

net/sunrpc/Kconfig

+16 −0
Original line number Diff line number Diff line
@@ -34,6 +34,22 @@ config RPCSEC_GSS_KRB5 


	  If unsure, say Y.



config CONFIG_SUNRPC_DISABLE_INSECURE_ENCTYPES

	bool "Secure RPC: Disable insecure Kerberos encryption types"

	depends on RPCSEC_GSS_KRB5

	default n

	help

	  Choose Y here to disable the use of deprecated encryption types

	  with the Kerberos version 5 GSS-API mechanism (RFC 1964). The

	  deprecated encryption types include DES-CBC-MD5, DES-CBC-CRC,

	  and DES-CBC-MD4. These types were deprecated by RFC 6649 because

	  they were found to be insecure.



	  N is the default because many sites have deployed KDCs and

	  keytabs that contain only these deprecated encryption types.

	  Choosing Y prevents the use of known-insecure encryption types

	  but might result in compatibility problems.



config SUNRPC_DEBUG

	bool "RPC: Enable dprintk debugging"

	depends on SUNRPC && SYSCTL

net/sunrpc/auth_gss/gss_krb5_mech.c

+2 −0
Original line number Diff line number Diff line
@@ -53,6 +53,7 @@ 
static struct gss_api_mech gss_kerberos_mech;	/* forward declaration */



static const struct gss_krb5_enctype supported_gss_krb5_enctypes[] = {

#ifndef CONFIG_SUNRPC_DISABLE_INSECURE_ENCTYPES

	/*

	 * DES (All DES enctypes are mapped to the same gss functionality)

	 */
@@ -74,6 +75,7 @@ static const struct gss_krb5_enctype supported_gss_krb5_enctypes[] = { 
	  .cksumlength = 8,

	  .keyed_cksum = 0,

	},

#endif	/* CONFIG_SUNRPC_DISABLE_INSECURE_ENCTYPES */

	/*

	 * RC4-HMAC

	 */