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kernel/include/linux/sunrpc/gss_krb5.h
Ard Biesheuvel e33d2a7b30 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Note that other outdated algorithms are left in place (some of which are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 <ardb@kernel.org>
Acked-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2020-09-11 14:39:15 +10:00

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/*
* linux/include/linux/sunrpc/gss_krb5_types.h
*
* Adapted from MIT Kerberos 5-1.2.1 lib/include/krb5.h,
* lib/gssapi/krb5/gssapiP_krb5.h, and others
*
* Copyright (c) 2000-2008 The Regents of the University of Michigan.
* All rights reserved.
*
* Andy Adamson <andros@umich.edu>
* Bruce Fields <bfields@umich.edu>
*/
/*
* Copyright 1995 by the Massachusetts Institute of Technology.
* All Rights Reserved.
*
* Export of this software from the United States of America may
* require a specific license from the United States Government.
* It is the responsibility of any person or organization contemplating
* export to obtain such a license before exporting.
*
* WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
* distribute this software and its documentation for any purpose and
* without fee is hereby granted, provided that the above copyright
* notice appear in all copies and that both that copyright notice and
* this permission notice appear in supporting documentation, and that
* the name of M.I.T. not be used in advertising or publicity pertaining
* to distribution of the software without specific, written prior
* permission. Furthermore if you modify this software you must label
* your software as modified software and not distribute it in such a
* fashion that it might be confused with the original M.I.T. software.
* M.I.T. makes no representations about the suitability of
* this software for any purpose. It is provided "as is" without express
* or implied warranty.
*
*/
#include <crypto/skcipher.h>
#include <linux/sunrpc/auth_gss.h>
#include <linux/sunrpc/gss_err.h>
#include <linux/sunrpc/gss_asn1.h>
/* Length of constant used in key derivation */
#define GSS_KRB5_K5CLENGTH (5)
/* Maximum key length (in bytes) for the supported crypto algorithms*/
#define GSS_KRB5_MAX_KEYLEN (32)
/* Maximum checksum function output for the supported crypto algorithms */
#define GSS_KRB5_MAX_CKSUM_LEN (20)
/* Maximum blocksize for the supported crypto algorithms */
#define GSS_KRB5_MAX_BLOCKSIZE (16)
struct krb5_ctx;
struct gss_krb5_enctype {
const u32 etype; /* encryption (key) type */
const u32 ctype; /* checksum type */
const char *name; /* "friendly" name */
const char *encrypt_name; /* crypto encrypt name */
const char *cksum_name; /* crypto checksum name */
const u16 signalg; /* signing algorithm */
const u16 sealalg; /* sealing algorithm */
const u32 blocksize; /* encryption blocksize */
const u32 conflen; /* confounder length
(normally the same as
the blocksize) */
const u32 cksumlength; /* checksum length */
const u32 keyed_cksum; /* is it a keyed cksum? */
const u32 keybytes; /* raw key len, in bytes */
const u32 keylength; /* final key len, in bytes */
u32 (*encrypt) (struct crypto_sync_skcipher *tfm,
void *iv, void *in, void *out,
int length); /* encryption function */
u32 (*decrypt) (struct crypto_sync_skcipher *tfm,
void *iv, void *in, void *out,
int length); /* decryption function */
u32 (*mk_key) (const struct gss_krb5_enctype *gk5e,
struct xdr_netobj *in,
struct xdr_netobj *out); /* complete key generation */
u32 (*encrypt_v2) (struct krb5_ctx *kctx, u32 offset,
struct xdr_buf *buf,
struct page **pages); /* v2 encryption function */
u32 (*decrypt_v2) (struct krb5_ctx *kctx, u32 offset, u32 len,
struct xdr_buf *buf, u32 *headskip,
u32 *tailskip); /* v2 decryption function */
};
/* krb5_ctx flags definitions */
#define KRB5_CTX_FLAG_INITIATOR 0x00000001
#define KRB5_CTX_FLAG_CFX 0x00000002
#define KRB5_CTX_FLAG_ACCEPTOR_SUBKEY 0x00000004
struct krb5_ctx {
int initiate; /* 1 = initiating, 0 = accepting */
u32 enctype;
u32 flags;
const struct gss_krb5_enctype *gk5e; /* enctype-specific info */
struct crypto_sync_skcipher *enc;
struct crypto_sync_skcipher *seq;
struct crypto_sync_skcipher *acceptor_enc;
struct crypto_sync_skcipher *initiator_enc;
struct crypto_sync_skcipher *acceptor_enc_aux;
struct crypto_sync_skcipher *initiator_enc_aux;
u8 Ksess[GSS_KRB5_MAX_KEYLEN]; /* session key */
u8 cksum[GSS_KRB5_MAX_KEYLEN];
atomic_t seq_send;
atomic64_t seq_send64;
time64_t endtime;
struct xdr_netobj mech_used;
u8 initiator_sign[GSS_KRB5_MAX_KEYLEN];
u8 acceptor_sign[GSS_KRB5_MAX_KEYLEN];
u8 initiator_seal[GSS_KRB5_MAX_KEYLEN];
u8 acceptor_seal[GSS_KRB5_MAX_KEYLEN];
u8 initiator_integ[GSS_KRB5_MAX_KEYLEN];
u8 acceptor_integ[GSS_KRB5_MAX_KEYLEN];
};
/* The length of the Kerberos GSS token header */
#define GSS_KRB5_TOK_HDR_LEN (16)
#define KG_TOK_MIC_MSG 0x0101
#define KG_TOK_WRAP_MSG 0x0201
#define KG2_TOK_INITIAL 0x0101
#define KG2_TOK_RESPONSE 0x0202
#define KG2_TOK_MIC 0x0404
#define KG2_TOK_WRAP 0x0504
#define KG2_TOKEN_FLAG_SENTBYACCEPTOR 0x01
#define KG2_TOKEN_FLAG_SEALED 0x02
#define KG2_TOKEN_FLAG_ACCEPTORSUBKEY 0x04
#define KG2_RESP_FLAG_ERROR 0x0001
#define KG2_RESP_FLAG_DELEG_OK 0x0002
enum sgn_alg {
SGN_ALG_DES_MAC_MD5 = 0x0000,
SGN_ALG_MD2_5 = 0x0001,
SGN_ALG_DES_MAC = 0x0002,
SGN_ALG_3 = 0x0003, /* not published */
SGN_ALG_HMAC_SHA1_DES3_KD = 0x0004
};
enum seal_alg {
SEAL_ALG_NONE = 0xffff,
SEAL_ALG_DES = 0x0000,
SEAL_ALG_1 = 0x0001, /* not published */
SEAL_ALG_DES3KD = 0x0002
};
#define CKSUMTYPE_CRC32 0x0001
#define CKSUMTYPE_RSA_MD4 0x0002
#define CKSUMTYPE_RSA_MD4_DES 0x0003
#define CKSUMTYPE_DESCBC 0x0004
#define CKSUMTYPE_RSA_MD5 0x0007
#define CKSUMTYPE_RSA_MD5_DES 0x0008
#define CKSUMTYPE_NIST_SHA 0x0009
#define CKSUMTYPE_HMAC_SHA1_DES3 0x000c
#define CKSUMTYPE_HMAC_SHA1_96_AES128 0x000f
#define CKSUMTYPE_HMAC_SHA1_96_AES256 0x0010
#define CKSUMTYPE_HMAC_MD5_ARCFOUR -138 /* Microsoft md5 hmac cksumtype */
/* from gssapi_err_krb5.h */
#define KG_CCACHE_NOMATCH (39756032L)
#define KG_KEYTAB_NOMATCH (39756033L)
#define KG_TGT_MISSING (39756034L)
#define KG_NO_SUBKEY (39756035L)
#define KG_CONTEXT_ESTABLISHED (39756036L)
#define KG_BAD_SIGN_TYPE (39756037L)
#define KG_BAD_LENGTH (39756038L)
#define KG_CTX_INCOMPLETE (39756039L)
#define KG_CONTEXT (39756040L)
#define KG_CRED (39756041L)
#define KG_ENC_DESC (39756042L)
#define KG_BAD_SEQ (39756043L)
#define KG_EMPTY_CCACHE (39756044L)
#define KG_NO_CTYPES (39756045L)
/* per Kerberos v5 protocol spec crypto types from the wire.
* these get mapped to linux kernel crypto routines.
*/
#define ENCTYPE_NULL 0x0000
#define ENCTYPE_DES_CBC_CRC 0x0001 /* DES cbc mode with CRC-32 */
#define ENCTYPE_DES_CBC_MD4 0x0002 /* DES cbc mode with RSA-MD4 */
#define ENCTYPE_DES_CBC_MD5 0x0003 /* DES cbc mode with RSA-MD5 */
#define ENCTYPE_DES_CBC_RAW 0x0004 /* DES cbc mode raw */
/* XXX deprecated? */
#define ENCTYPE_DES3_CBC_SHA 0x0005 /* DES-3 cbc mode with NIST-SHA */
#define ENCTYPE_DES3_CBC_RAW 0x0006 /* DES-3 cbc mode raw */
#define ENCTYPE_DES_HMAC_SHA1 0x0008
#define ENCTYPE_DES3_CBC_SHA1 0x0010
#define ENCTYPE_AES128_CTS_HMAC_SHA1_96 0x0011
#define ENCTYPE_AES256_CTS_HMAC_SHA1_96 0x0012
#define ENCTYPE_ARCFOUR_HMAC 0x0017
#define ENCTYPE_ARCFOUR_HMAC_EXP 0x0018
#define ENCTYPE_UNKNOWN 0x01ff
/*
* Constants used for key derivation
*/
/* for 3DES */
#define KG_USAGE_SEAL (22)
#define KG_USAGE_SIGN (23)
#define KG_USAGE_SEQ (24)
/* from rfc3961 */
#define KEY_USAGE_SEED_CHECKSUM (0x99)
#define KEY_USAGE_SEED_ENCRYPTION (0xAA)
#define KEY_USAGE_SEED_INTEGRITY (0x55)
/* from rfc4121 */
#define KG_USAGE_ACCEPTOR_SEAL (22)
#define KG_USAGE_ACCEPTOR_SIGN (23)
#define KG_USAGE_INITIATOR_SEAL (24)
#define KG_USAGE_INITIATOR_SIGN (25)
/*
* This compile-time check verifies that we will not exceed the
* slack space allotted by the client and server auth_gss code
* before they call gss_wrap().
*/
#define GSS_KRB5_MAX_SLACK_NEEDED \
(GSS_KRB5_TOK_HDR_LEN /* gss token header */ \
+ GSS_KRB5_MAX_CKSUM_LEN /* gss token checksum */ \
+ GSS_KRB5_MAX_BLOCKSIZE /* confounder */ \
+ GSS_KRB5_MAX_BLOCKSIZE /* possible padding */ \
+ GSS_KRB5_TOK_HDR_LEN /* encrypted hdr in v2 token */\
+ GSS_KRB5_MAX_CKSUM_LEN /* encryption hmac */ \
+ 4 + 4 /* RPC verifier */ \
+ GSS_KRB5_TOK_HDR_LEN \
+ GSS_KRB5_MAX_CKSUM_LEN)
u32
make_checksum(struct krb5_ctx *kctx, char *header, int hdrlen,
struct xdr_buf *body, int body_offset, u8 *cksumkey,
unsigned int usage, struct xdr_netobj *cksumout);
u32
make_checksum_v2(struct krb5_ctx *, char *header, int hdrlen,
struct xdr_buf *body, int body_offset, u8 *key,
unsigned int usage, struct xdr_netobj *cksum);
u32 gss_get_mic_kerberos(struct gss_ctx *, struct xdr_buf *,
struct xdr_netobj *);
u32 gss_verify_mic_kerberos(struct gss_ctx *, struct xdr_buf *,
struct xdr_netobj *);
u32
gss_wrap_kerberos(struct gss_ctx *ctx_id, int offset,
struct xdr_buf *outbuf, struct page **pages);
u32
gss_unwrap_kerberos(struct gss_ctx *ctx_id, int offset, int len,
struct xdr_buf *buf);
u32
krb5_encrypt(struct crypto_sync_skcipher *key,
void *iv, void *in, void *out, int length);
u32
krb5_decrypt(struct crypto_sync_skcipher *key,
void *iv, void *in, void *out, int length);
int
gss_encrypt_xdr_buf(struct crypto_sync_skcipher *tfm, struct xdr_buf *outbuf,
int offset, struct page **pages);
int
gss_decrypt_xdr_buf(struct crypto_sync_skcipher *tfm, struct xdr_buf *inbuf,
int offset);
s32
krb5_make_seq_num(struct krb5_ctx *kctx,
struct crypto_sync_skcipher *key,
int direction,
u32 seqnum, unsigned char *cksum, unsigned char *buf);
s32
krb5_get_seq_num(struct krb5_ctx *kctx,
unsigned char *cksum,
unsigned char *buf, int *direction, u32 *seqnum);
int
xdr_extend_head(struct xdr_buf *buf, unsigned int base, unsigned int shiftlen);
u32
krb5_derive_key(const struct gss_krb5_enctype *gk5e,
const struct xdr_netobj *inkey,
struct xdr_netobj *outkey,
const struct xdr_netobj *in_constant,
gfp_t gfp_mask);
u32
gss_krb5_des3_make_key(const struct gss_krb5_enctype *gk5e,
struct xdr_netobj *randombits,
struct xdr_netobj *key);
u32
gss_krb5_aes_make_key(const struct gss_krb5_enctype *gk5e,
struct xdr_netobj *randombits,
struct xdr_netobj *key);
u32
gss_krb5_aes_encrypt(struct krb5_ctx *kctx, u32 offset,
struct xdr_buf *buf,
struct page **pages);
u32
gss_krb5_aes_decrypt(struct krb5_ctx *kctx, u32 offset, u32 len,
struct xdr_buf *buf, u32 *plainoffset,
u32 *plainlen);
void
gss_krb5_make_confounder(char *p, u32 conflen);
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