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![Ard Biesheuvel](/assets/img/avatar_default.png)
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by RFC 8429 [1] in 2018, stating that 'none of the encryption types it specifies should be used' Note that other outdated algorithms are left in place (some of which are guarded by CONFIG_SUNRPC_DISABLE_INSECURE_ENCTYPES), so this should only adversely affect interoperability with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>
80 lines
2.4 KiB
Text
80 lines
2.4 KiB
Text
# SPDX-License-Identifier: GPL-2.0-only
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config SUNRPC
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tristate
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depends on MULTIUSER
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config SUNRPC_GSS
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tristate
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select OID_REGISTRY
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depends on MULTIUSER
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config SUNRPC_BACKCHANNEL
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bool
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depends on SUNRPC
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config SUNRPC_SWAP
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bool
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depends on SUNRPC
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config RPCSEC_GSS_KRB5
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tristate "Secure RPC: Kerberos V mechanism"
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depends on SUNRPC && CRYPTO
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depends on CRYPTO_MD5 && CRYPTO_DES && CRYPTO_CBC && CRYPTO_CTS
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depends on CRYPTO_ECB && CRYPTO_HMAC && CRYPTO_SHA1 && CRYPTO_AES
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default y
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select SUNRPC_GSS
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help
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Choose Y here to enable Secure RPC using the Kerberos version 5
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GSS-API mechanism (RFC 1964).
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Secure RPC calls with Kerberos require an auxiliary user-space
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daemon which may be found in the Linux nfs-utils package
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available from http://linux-nfs.org/. In addition, user-space
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Kerberos support should be installed.
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If unsure, say Y.
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config SUNRPC_DISABLE_INSECURE_ENCTYPES
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bool "Secure RPC: Disable insecure Kerberos encryption types"
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depends on RPCSEC_GSS_KRB5
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default n
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help
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Choose Y here to disable the use of deprecated encryption types
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with the Kerberos version 5 GSS-API mechanism (RFC 1964). The
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deprecated encryption types include DES-CBC-MD5, DES-CBC-CRC,
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and DES-CBC-MD4. These types were deprecated by RFC 6649 because
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they were found to be insecure.
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N is the default because many sites have deployed KDCs and
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keytabs that contain only these deprecated encryption types.
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Choosing Y prevents the use of known-insecure encryption types
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but might result in compatibility problems.
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config SUNRPC_DEBUG
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bool "RPC: Enable dprintk debugging"
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depends on SUNRPC && SYSCTL
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select DEBUG_FS
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help
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This option enables a sysctl-based debugging interface
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that is be used by the 'rpcdebug' utility to turn on or off
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logging of different aspects of the kernel RPC activity.
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Disabling this option will make your kernel slightly smaller,
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but makes troubleshooting NFS issues significantly harder.
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If unsure, say Y.
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config SUNRPC_XPRT_RDMA
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tristate "RPC-over-RDMA transport"
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depends on SUNRPC && INFINIBAND && INFINIBAND_ADDR_TRANS
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default SUNRPC && INFINIBAND
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select SG_POOL
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help
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This option allows the NFS client and server to use RDMA
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transports (InfiniBand, iWARP, or RoCE).
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To compile this support as a module, choose M. The module
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will be called rpcrdma.ko.
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If unsure, or you know there is no RDMA capability on your
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hardware platform, say N.
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