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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by RFC 8429 [1] in 2018, stating that 'none of the encryption types it specifies should be used' Note that other outdated algorithms are left in place (some of which are guarded by CONFIG_SUNRPC_DISABLE_INSECURE_ENCTYPES), so this should only adversely affect interoperability with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 <ardb@kernel.org> Acked-by: J. Bruce Fields <bfields@redhat.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
105 lines
2.8 KiB
C
105 lines
2.8 KiB
C
/*
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* linux/net/sunrpc/gss_krb5_seqnum.c
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*
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* Adapted from MIT Kerberos 5-1.2.1 lib/gssapi/krb5/util_seqnum.c
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*
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* Copyright (c) 2000 The Regents of the University of Michigan.
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* All rights reserved.
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*
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* Andy Adamson <andros@umich.edu>
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*/
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/*
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* Copyright 1993 by OpenVision Technologies, Inc.
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*
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* Permission to use, copy, modify, distribute, and sell this software
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* and its documentation for any purpose is hereby granted without fee,
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* provided that the above copyright notice appears in all copies and
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* that both that copyright notice and this permission notice appear in
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* supporting documentation, and that the name of OpenVision not be used
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* in advertising or publicity pertaining to distribution of the software
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* without specific, written prior permission. OpenVision makes no
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* representations about the suitability of this software for any
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* purpose. It is provided "as is" without express or implied warranty.
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*
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* OPENVISION DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
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* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
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* EVENT SHALL OPENVISION BE LIABLE FOR ANY SPECIAL, INDIRECT OR
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* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF
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* USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
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* OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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* PERFORMANCE OF THIS SOFTWARE.
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*/
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#include <crypto/skcipher.h>
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#include <linux/types.h>
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#include <linux/sunrpc/gss_krb5.h>
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#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
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# define RPCDBG_FACILITY RPCDBG_AUTH
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#endif
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s32
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krb5_make_seq_num(struct krb5_ctx *kctx,
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struct crypto_sync_skcipher *key,
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int direction,
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u32 seqnum,
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unsigned char *cksum, unsigned char *buf)
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{
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unsigned char *plain;
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s32 code;
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plain = kmalloc(8, GFP_NOFS);
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if (!plain)
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return -ENOMEM;
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plain[0] = (unsigned char) (seqnum & 0xff);
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plain[1] = (unsigned char) ((seqnum >> 8) & 0xff);
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plain[2] = (unsigned char) ((seqnum >> 16) & 0xff);
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plain[3] = (unsigned char) ((seqnum >> 24) & 0xff);
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plain[4] = direction;
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plain[5] = direction;
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plain[6] = direction;
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plain[7] = direction;
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code = krb5_encrypt(key, cksum, plain, buf, 8);
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kfree(plain);
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return code;
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}
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s32
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krb5_get_seq_num(struct krb5_ctx *kctx,
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unsigned char *cksum,
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unsigned char *buf,
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int *direction, u32 *seqnum)
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{
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s32 code;
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unsigned char *plain;
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struct crypto_sync_skcipher *key = kctx->seq;
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dprintk("RPC: krb5_get_seq_num:\n");
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plain = kmalloc(8, GFP_NOFS);
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if (!plain)
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return -ENOMEM;
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if ((code = krb5_decrypt(key, cksum, buf, plain, 8)))
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goto out;
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if ((plain[4] != plain[5]) || (plain[4] != plain[6]) ||
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(plain[4] != plain[7])) {
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code = (s32)KG_BAD_SEQ;
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goto out;
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}
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*direction = plain[4];
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*seqnum = ((plain[0]) |
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(plain[1] << 8) | (plain[2] << 16) | (plain[3] << 24));
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out:
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kfree(plain);
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return code;
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}
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