Re: [RFC PATCH 3/7] SUNRPC: remove RC4-HMAC-MD5 support from KerberosV

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Acked-by: J. Bruce Fields <bfields@xxxxxxxxxx>

On Thu, Jul 02, 2020 at 12:19:43PM +0200, Ard Biesheuvel wrote:
> 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 Note that other outdated algorithms are left in place (some of which are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@xxxxxxxxxx>
> ---
>  include/linux/sunrpc/gss_krb5.h          |  11 -
>  include/linux/sunrpc/gss_krb5_enctypes.h |   9 +-
>  net/sunrpc/Kconfig                       |   1 -
>  net/sunrpc/auth_gss/gss_krb5_crypto.c    | 276 --------------------
>  net/sunrpc/auth_gss/gss_krb5_mech.c      |  95 -------
>  net/sunrpc/auth_gss/gss_krb5_seal.c      |   1 -
>  net/sunrpc/auth_gss/gss_krb5_seqnum.c    |  87 ------
>  net/sunrpc/auth_gss/gss_krb5_unseal.c    |   1 -
>  net/sunrpc/auth_gss/gss_krb5_wrap.c      |  65 +----
>  9 files changed, 16 insertions(+), 530 deletions(-)
> 
> diff --git a/include/linux/sunrpc/gss_krb5.h b/include/linux/sunrpc/gss_krb5.h
> index e8f8ffe7448b..91f43d86879d 100644
> --- a/include/linux/sunrpc/gss_krb5.h
> +++ b/include/linux/sunrpc/gss_krb5.h
> @@ -141,14 +141,12 @@ enum sgn_alg {
>  	SGN_ALG_MD2_5 = 0x0001,
>  	SGN_ALG_DES_MAC = 0x0002,
>  	SGN_ALG_3 = 0x0003,		/* not published */
> -	SGN_ALG_HMAC_MD5 = 0x0011,	/* microsoft w2k; no support */
>  	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_MICROSOFT_RC4 = 0x0010,/* microsoft w2k; no support */
>  	SEAL_ALG_DES3KD = 0x0002
>  };
>  
> @@ -316,14 +314,5 @@ gss_krb5_aes_decrypt(struct krb5_ctx *kctx, u32 offset, u32 len,
>  		     struct xdr_buf *buf, u32 *plainoffset,
>  		     u32 *plainlen);
>  
> -int
> -krb5_rc4_setup_seq_key(struct krb5_ctx *kctx,
> -		       struct crypto_sync_skcipher *cipher,
> -		       unsigned char *cksum);
> -
> -int
> -krb5_rc4_setup_enc_key(struct krb5_ctx *kctx,
> -		       struct crypto_sync_skcipher *cipher,
> -		       s32 seqnum);
>  void
>  gss_krb5_make_confounder(char *p, u32 conflen);
> diff --git a/include/linux/sunrpc/gss_krb5_enctypes.h b/include/linux/sunrpc/gss_krb5_enctypes.h
> index 981c89cef19d..87eea679d750 100644
> --- a/include/linux/sunrpc/gss_krb5_enctypes.h
> +++ b/include/linux/sunrpc/gss_krb5_enctypes.h
> @@ -13,15 +13,13 @@
>  #ifdef CONFIG_SUNRPC_DISABLE_INSECURE_ENCTYPES
>  
>  /*
> - * NB: This list includes encryption types that were deprecated
> - * by RFC 8429 (DES3_CBC_SHA1 and ARCFOUR_HMAC).
> + * NB: This list includes DES3_CBC_SHA1, which was deprecated by RFC 8429.
>   *
>   * 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"
> +#define KRB5_SUPPORTED_ENCTYPES "18,17,16"
>  
>  #else	/* CONFIG_SUNRPC_DISABLE_INSECURE_ENCTYPES */
>  
> @@ -32,12 +30,11 @@
>   * 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"
> +#define KRB5_SUPPORTED_ENCTYPES "18,17,16,3,1,2"
>  
>  #endif	/* CONFIG_SUNRPC_DISABLE_INSECURE_ENCTYPES */
>  
> 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
> diff --git a/net/sunrpc/auth_gss/gss_krb5_crypto.c b/net/sunrpc/auth_gss/gss_krb5_crypto.c
> index e7180da1fc6a..634b6c6e0dcb 100644
> --- a/net/sunrpc/auth_gss/gss_krb5_crypto.c
> +++ b/net/sunrpc/auth_gss/gss_krb5_crypto.c
> @@ -138,135 +138,6 @@ checksummer(struct scatterlist *sg, void *data)
>  	return crypto_ahash_update(req);
>  }
>  
> -static int
> -arcfour_hmac_md5_usage_to_salt(unsigned int usage, u8 salt[4])
> -{
> -	unsigned int ms_usage;
> -
> -	switch (usage) {
> -	case KG_USAGE_SIGN:
> -		ms_usage = 15;
> -		break;
> -	case KG_USAGE_SEAL:
> -		ms_usage = 13;
> -		break;
> -	default:
> -		return -EINVAL;
> -	}
> -	salt[0] = (ms_usage >> 0) & 0xff;
> -	salt[1] = (ms_usage >> 8) & 0xff;
> -	salt[2] = (ms_usage >> 16) & 0xff;
> -	salt[3] = (ms_usage >> 24) & 0xff;
> -
> -	return 0;
> -}
> -
> -static u32
> -make_checksum_hmac_md5(struct krb5_ctx *kctx, char *header, int hdrlen,
> -		       struct xdr_buf *body, int body_offset, u8 *cksumkey,
> -		       unsigned int usage, struct xdr_netobj *cksumout)
> -{
> -	struct scatterlist              sg[1];
> -	int err = -1;
> -	u8 *checksumdata;
> -	u8 *rc4salt;
> -	struct crypto_ahash *md5;
> -	struct crypto_ahash *hmac_md5;
> -	struct ahash_request *req;
> -
> -	if (cksumkey == NULL)
> -		return GSS_S_FAILURE;
> -
> -	if (cksumout->len < kctx->gk5e->cksumlength) {
> -		dprintk("%s: checksum buffer length, %u, too small for %s\n",
> -			__func__, cksumout->len, kctx->gk5e->name);
> -		return GSS_S_FAILURE;
> -	}
> -
> -	rc4salt = kmalloc_array(4, sizeof(*rc4salt), GFP_NOFS);
> -	if (!rc4salt)
> -		return GSS_S_FAILURE;
> -
> -	if (arcfour_hmac_md5_usage_to_salt(usage, rc4salt)) {
> -		dprintk("%s: invalid usage value %u\n", __func__, usage);
> -		goto out_free_rc4salt;
> -	}
> -
> -	checksumdata = kmalloc(GSS_KRB5_MAX_CKSUM_LEN, GFP_NOFS);
> -	if (!checksumdata)
> -		goto out_free_rc4salt;
> -
> -	md5 = crypto_alloc_ahash("md5", 0, CRYPTO_ALG_ASYNC);
> -	if (IS_ERR(md5))
> -		goto out_free_cksum;
> -
> -	hmac_md5 = crypto_alloc_ahash(kctx->gk5e->cksum_name, 0,
> -				      CRYPTO_ALG_ASYNC);
> -	if (IS_ERR(hmac_md5))
> -		goto out_free_md5;
> -
> -	req = ahash_request_alloc(md5, GFP_NOFS);
> -	if (!req)
> -		goto out_free_hmac_md5;
> -
> -	ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
> -
> -	err = crypto_ahash_init(req);
> -	if (err)
> -		goto out;
> -	sg_init_one(sg, rc4salt, 4);
> -	ahash_request_set_crypt(req, sg, NULL, 4);
> -	err = crypto_ahash_update(req);
> -	if (err)
> -		goto out;
> -
> -	sg_init_one(sg, header, hdrlen);
> -	ahash_request_set_crypt(req, sg, NULL, hdrlen);
> -	err = crypto_ahash_update(req);
> -	if (err)
> -		goto out;
> -	err = xdr_process_buf(body, body_offset, body->len - body_offset,
> -			      checksummer, req);
> -	if (err)
> -		goto out;
> -	ahash_request_set_crypt(req, NULL, checksumdata, 0);
> -	err = crypto_ahash_final(req);
> -	if (err)
> -		goto out;
> -
> -	ahash_request_free(req);
> -	req = ahash_request_alloc(hmac_md5, GFP_NOFS);
> -	if (!req)
> -		goto out_free_hmac_md5;
> -
> -	ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
> -
> -	err = crypto_ahash_setkey(hmac_md5, cksumkey, kctx->gk5e->keylength);
> -	if (err)
> -		goto out;
> -
> -	sg_init_one(sg, checksumdata, crypto_ahash_digestsize(md5));
> -	ahash_request_set_crypt(req, sg, checksumdata,
> -				crypto_ahash_digestsize(md5));
> -	err = crypto_ahash_digest(req);
> -	if (err)
> -		goto out;
> -
> -	memcpy(cksumout->data, checksumdata, kctx->gk5e->cksumlength);
> -	cksumout->len = kctx->gk5e->cksumlength;
> -out:
> -	ahash_request_free(req);
> -out_free_hmac_md5:
> -	crypto_free_ahash(hmac_md5);
> -out_free_md5:
> -	crypto_free_ahash(md5);
> -out_free_cksum:
> -	kfree(checksumdata);
> -out_free_rc4salt:
> -	kfree(rc4salt);
> -	return err ? GSS_S_FAILURE : 0;
> -}
> -
>  /*
>   * checksum the plaintext data and hdrlen bytes of the token header
>   * The checksum is performed over the first 8 bytes of the
> @@ -284,11 +155,6 @@ make_checksum(struct krb5_ctx *kctx, char *header, int hdrlen,
>  	u8 *checksumdata;
>  	unsigned int checksumlen;
>  
> -	if (kctx->gk5e->ctype == CKSUMTYPE_HMAC_MD5_ARCFOUR)
> -		return make_checksum_hmac_md5(kctx, header, hdrlen,
> -					      body, body_offset,
> -					      cksumkey, usage, cksumout);
> -
>  	if (cksumout->len < kctx->gk5e->cksumlength) {
>  		dprintk("%s: checksum buffer length, %u, too small for %s\n",
>  			__func__, cksumout->len, kctx->gk5e->name);
> @@ -942,145 +808,3 @@ gss_krb5_aes_decrypt(struct krb5_ctx *kctx, u32 offset, u32 len,
>  		ret = GSS_S_FAILURE;
>  	return ret;
>  }
> -
> -/*
> - * Compute Kseq given the initial session key and the checksum.
> - * Set the key of the given cipher.
> - */
> -int
> -krb5_rc4_setup_seq_key(struct krb5_ctx *kctx,
> -		       struct crypto_sync_skcipher *cipher,
> -		       unsigned char *cksum)
> -{
> -	struct crypto_shash *hmac;
> -	struct shash_desc *desc;
> -	u8 Kseq[GSS_KRB5_MAX_KEYLEN];
> -	u32 zeroconstant = 0;
> -	int err;
> -
> -	dprintk("%s: entered\n", __func__);
> -
> -	hmac = crypto_alloc_shash(kctx->gk5e->cksum_name, 0, 0);
> -	if (IS_ERR(hmac)) {
> -		dprintk("%s: error %ld, allocating hash '%s'\n",
> -			__func__, PTR_ERR(hmac), kctx->gk5e->cksum_name);
> -		return PTR_ERR(hmac);
> -	}
> -
> -	desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(hmac),
> -		       GFP_NOFS);
> -	if (!desc) {
> -		dprintk("%s: failed to allocate shash descriptor for '%s'\n",
> -			__func__, kctx->gk5e->cksum_name);
> -		crypto_free_shash(hmac);
> -		return -ENOMEM;
> -	}
> -
> -	desc->tfm = hmac;
> -
> -	/* Compute intermediate Kseq from session key */
> -	err = crypto_shash_setkey(hmac, kctx->Ksess, kctx->gk5e->keylength);
> -	if (err)
> -		goto out_err;
> -
> -	err = crypto_shash_digest(desc, (u8 *)&zeroconstant, 4, Kseq);
> -	if (err)
> -		goto out_err;
> -
> -	/* Compute final Kseq from the checksum and intermediate Kseq */
> -	err = crypto_shash_setkey(hmac, Kseq, kctx->gk5e->keylength);
> -	if (err)
> -		goto out_err;
> -
> -	err = crypto_shash_digest(desc, cksum, 8, Kseq);
> -	if (err)
> -		goto out_err;
> -
> -	err = crypto_sync_skcipher_setkey(cipher, Kseq, kctx->gk5e->keylength);
> -	if (err)
> -		goto out_err;
> -
> -	err = 0;
> -
> -out_err:
> -	kzfree(desc);
> -	crypto_free_shash(hmac);
> -	dprintk("%s: returning %d\n", __func__, err);
> -	return err;
> -}
> -
> -/*
> - * Compute Kcrypt given the initial session key and the plaintext seqnum.
> - * Set the key of cipher kctx->enc.
> - */
> -int
> -krb5_rc4_setup_enc_key(struct krb5_ctx *kctx,
> -		       struct crypto_sync_skcipher *cipher,
> -		       s32 seqnum)
> -{
> -	struct crypto_shash *hmac;
> -	struct shash_desc *desc;
> -	u8 Kcrypt[GSS_KRB5_MAX_KEYLEN];
> -	u8 zeroconstant[4] = {0};
> -	u8 seqnumarray[4];
> -	int err, i;
> -
> -	dprintk("%s: entered, seqnum %u\n", __func__, seqnum);
> -
> -	hmac = crypto_alloc_shash(kctx->gk5e->cksum_name, 0, 0);
> -	if (IS_ERR(hmac)) {
> -		dprintk("%s: error %ld, allocating hash '%s'\n",
> -			__func__, PTR_ERR(hmac), kctx->gk5e->cksum_name);
> -		return PTR_ERR(hmac);
> -	}
> -
> -	desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(hmac),
> -		       GFP_NOFS);
> -	if (!desc) {
> -		dprintk("%s: failed to allocate shash descriptor for '%s'\n",
> -			__func__, kctx->gk5e->cksum_name);
> -		crypto_free_shash(hmac);
> -		return -ENOMEM;
> -	}
> -
> -	desc->tfm = hmac;
> -
> -	/* Compute intermediate Kcrypt from session key */
> -	for (i = 0; i < kctx->gk5e->keylength; i++)
> -		Kcrypt[i] = kctx->Ksess[i] ^ 0xf0;
> -
> -	err = crypto_shash_setkey(hmac, Kcrypt, kctx->gk5e->keylength);
> -	if (err)
> -		goto out_err;
> -
> -	err = crypto_shash_digest(desc, zeroconstant, 4, Kcrypt);
> -	if (err)
> -		goto out_err;
> -
> -	/* Compute final Kcrypt from the seqnum and intermediate Kcrypt */
> -	err = crypto_shash_setkey(hmac, Kcrypt, kctx->gk5e->keylength);
> -	if (err)
> -		goto out_err;
> -
> -	seqnumarray[0] = (unsigned char) ((seqnum >> 24) & 0xff);
> -	seqnumarray[1] = (unsigned char) ((seqnum >> 16) & 0xff);
> -	seqnumarray[2] = (unsigned char) ((seqnum >> 8) & 0xff);
> -	seqnumarray[3] = (unsigned char) ((seqnum >> 0) & 0xff);
> -
> -	err = crypto_shash_digest(desc, seqnumarray, 4, Kcrypt);
> -	if (err)
> -		goto out_err;
> -
> -	err = crypto_sync_skcipher_setkey(cipher, Kcrypt,
> -					  kctx->gk5e->keylength);
> -	if (err)
> -		goto out_err;
> -
> -	err = 0;
> -
> -out_err:
> -	kzfree(desc);
> -	crypto_free_shash(hmac);
> -	dprintk("%s: returning %d\n", __func__, err);
> -	return err;
> -}
> diff --git a/net/sunrpc/auth_gss/gss_krb5_mech.c b/net/sunrpc/auth_gss/gss_krb5_mech.c
> index 75b3c2e9e8f8..ae9acf3a7389 100644
> --- a/net/sunrpc/auth_gss/gss_krb5_mech.c
> +++ b/net/sunrpc/auth_gss/gss_krb5_mech.c
> @@ -51,27 +51,6 @@ static const struct gss_krb5_enctype supported_gss_krb5_enctypes[] = {
>  	  .keyed_cksum = 0,
>  	},
>  #endif	/* CONFIG_SUNRPC_DISABLE_INSECURE_ENCTYPES */
> -	/*
> -	 * RC4-HMAC
> -	 */
> -	{
> -	  .etype = ENCTYPE_ARCFOUR_HMAC,
> -	  .ctype = CKSUMTYPE_HMAC_MD5_ARCFOUR,
> -	  .name = "rc4-hmac",
> -	  .encrypt_name = "ecb(arc4)",
> -	  .cksum_name = "hmac(md5)",
> -	  .encrypt = krb5_encrypt,
> -	  .decrypt = krb5_decrypt,
> -	  .mk_key = NULL,
> -	  .signalg = SGN_ALG_HMAC_MD5,
> -	  .sealalg = SEAL_ALG_MICROSOFT_RC4,
> -	  .keybytes = 16,
> -	  .keylength = 16,
> -	  .blocksize = 1,
> -	  .conflen = 8,
> -	  .cksumlength = 8,
> -	  .keyed_cksum = 1,
> -	},
>  	/*
>  	 * 3DES
>  	 */
> @@ -401,78 +380,6 @@ context_derive_keys_des3(struct krb5_ctx *ctx, gfp_t gfp_mask)
>  	return -EINVAL;
>  }
>  
> -/*
> - * Note that RC4 depends on deriving keys using the sequence
> - * number or the checksum of a token.  Therefore, the final keys
> - * cannot be calculated until the token is being constructed!
> - */
> -static int
> -context_derive_keys_rc4(struct krb5_ctx *ctx)
> -{
> -	struct crypto_shash *hmac;
> -	char sigkeyconstant[] = "signaturekey";
> -	int slen = strlen(sigkeyconstant) + 1;	/* include null terminator */
> -	struct shash_desc *desc;
> -	int err;
> -
> -	dprintk("RPC:       %s: entered\n", __func__);
> -	/*
> -	 * derive cksum (aka Ksign) key
> -	 */
> -	hmac = crypto_alloc_shash(ctx->gk5e->cksum_name, 0, 0);
> -	if (IS_ERR(hmac)) {
> -		dprintk("%s: error %ld allocating hash '%s'\n",
> -			__func__, PTR_ERR(hmac), ctx->gk5e->cksum_name);
> -		err = PTR_ERR(hmac);
> -		goto out_err;
> -	}
> -
> -	err = crypto_shash_setkey(hmac, ctx->Ksess, ctx->gk5e->keylength);
> -	if (err)
> -		goto out_err_free_hmac;
> -
> -
> -	desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(hmac), GFP_NOFS);
> -	if (!desc) {
> -		dprintk("%s: failed to allocate hash descriptor for '%s'\n",
> -			__func__, ctx->gk5e->cksum_name);
> -		err = -ENOMEM;
> -		goto out_err_free_hmac;
> -	}
> -
> -	desc->tfm = hmac;
> -
> -	err = crypto_shash_digest(desc, sigkeyconstant, slen, ctx->cksum);
> -	kzfree(desc);
> -	if (err)
> -		goto out_err_free_hmac;
> -	/*
> -	 * allocate hash, and skciphers for data and seqnum encryption
> -	 */
> -	ctx->enc = crypto_alloc_sync_skcipher(ctx->gk5e->encrypt_name, 0, 0);
> -	if (IS_ERR(ctx->enc)) {
> -		err = PTR_ERR(ctx->enc);
> -		goto out_err_free_hmac;
> -	}
> -
> -	ctx->seq = crypto_alloc_sync_skcipher(ctx->gk5e->encrypt_name, 0, 0);
> -	if (IS_ERR(ctx->seq)) {
> -		crypto_free_sync_skcipher(ctx->enc);
> -		err = PTR_ERR(ctx->seq);
> -		goto out_err_free_hmac;
> -	}
> -
> -	dprintk("RPC:       %s: returning success\n", __func__);
> -
> -	err = 0;
> -
> -out_err_free_hmac:
> -	crypto_free_shash(hmac);
> -out_err:
> -	dprintk("RPC:       %s: returning %d\n", __func__, err);
> -	return err;
> -}
> -
>  static int
>  context_derive_keys_new(struct krb5_ctx *ctx, gfp_t gfp_mask)
>  {
> @@ -649,8 +556,6 @@ gss_import_v2_context(const void *p, const void *end, struct krb5_ctx *ctx,
>  	switch (ctx->enctype) {
>  	case ENCTYPE_DES3_CBC_RAW:
>  		return context_derive_keys_des3(ctx, gfp_mask);
> -	case ENCTYPE_ARCFOUR_HMAC:
> -		return context_derive_keys_rc4(ctx);
>  	case ENCTYPE_AES128_CTS_HMAC_SHA1_96:
>  	case ENCTYPE_AES256_CTS_HMAC_SHA1_96:
>  		return context_derive_keys_new(ctx, gfp_mask);
> diff --git a/net/sunrpc/auth_gss/gss_krb5_seal.c b/net/sunrpc/auth_gss/gss_krb5_seal.c
> index f1d280accf43..33061417ec97 100644
> --- a/net/sunrpc/auth_gss/gss_krb5_seal.c
> +++ b/net/sunrpc/auth_gss/gss_krb5_seal.c
> @@ -214,7 +214,6 @@ gss_get_mic_kerberos(struct gss_ctx *gss_ctx, struct xdr_buf *text,
>  		BUG();
>  	case ENCTYPE_DES_CBC_RAW:
>  	case ENCTYPE_DES3_CBC_RAW:
> -	case ENCTYPE_ARCFOUR_HMAC:
>  		return gss_get_mic_v1(ctx, text, token);
>  	case ENCTYPE_AES128_CTS_HMAC_SHA1_96:
>  	case ENCTYPE_AES256_CTS_HMAC_SHA1_96:
> diff --git a/net/sunrpc/auth_gss/gss_krb5_seqnum.c b/net/sunrpc/auth_gss/gss_krb5_seqnum.c
> index 507105127095..fb117817ff5d 100644
> --- a/net/sunrpc/auth_gss/gss_krb5_seqnum.c
> +++ b/net/sunrpc/auth_gss/gss_krb5_seqnum.c
> @@ -39,42 +39,6 @@
>  # define RPCDBG_FACILITY        RPCDBG_AUTH
>  #endif
>  
> -static s32
> -krb5_make_rc4_seq_num(struct krb5_ctx *kctx, int direction, s32 seqnum,
> -		      unsigned char *cksum, unsigned char *buf)
> -{
> -	struct crypto_sync_skcipher *cipher;
> -	unsigned char *plain;
> -	s32 code;
> -
> -	dprintk("RPC:       %s:\n", __func__);
> -	cipher = crypto_alloc_sync_skcipher(kctx->gk5e->encrypt_name, 0, 0);
> -	if (IS_ERR(cipher))
> -		return PTR_ERR(cipher);
> -
> -	plain = kmalloc(8, GFP_NOFS);
> -	if (!plain)
> -		return -ENOMEM;
> -
> -	plain[0] = (unsigned char) ((seqnum >> 24) & 0xff);
> -	plain[1] = (unsigned char) ((seqnum >> 16) & 0xff);
> -	plain[2] = (unsigned char) ((seqnum >> 8) & 0xff);
> -	plain[3] = (unsigned char) ((seqnum >> 0) & 0xff);
> -	plain[4] = direction;
> -	plain[5] = direction;
> -	plain[6] = direction;
> -	plain[7] = direction;
> -
> -	code = krb5_rc4_setup_seq_key(kctx, cipher, cksum);
> -	if (code)
> -		goto out;
> -
> -	code = krb5_encrypt(cipher, cksum, plain, buf, 8);
> -out:
> -	kfree(plain);
> -	crypto_free_sync_skcipher(cipher);
> -	return code;
> -}
>  s32
>  krb5_make_seq_num(struct krb5_ctx *kctx,
>  		struct crypto_sync_skcipher *key,
> @@ -85,10 +49,6 @@ krb5_make_seq_num(struct krb5_ctx *kctx,
>  	unsigned char *plain;
>  	s32 code;
>  
> -	if (kctx->enctype == ENCTYPE_ARCFOUR_HMAC)
> -		return krb5_make_rc4_seq_num(kctx, direction, seqnum,
> -					     cksum, buf);
> -
>  	plain = kmalloc(8, GFP_NOFS);
>  	if (!plain)
>  		return -ENOMEM;
> @@ -108,50 +68,6 @@ krb5_make_seq_num(struct krb5_ctx *kctx,
>  	return code;
>  }
>  
> -static s32
> -krb5_get_rc4_seq_num(struct krb5_ctx *kctx, unsigned char *cksum,
> -		     unsigned char *buf, int *direction, s32 *seqnum)
> -{
> -	struct crypto_sync_skcipher *cipher;
> -	unsigned char *plain;
> -	s32 code;
> -
> -	dprintk("RPC:       %s:\n", __func__);
> -	cipher = crypto_alloc_sync_skcipher(kctx->gk5e->encrypt_name, 0, 0);
> -	if (IS_ERR(cipher))
> -		return PTR_ERR(cipher);
> -
> -	code = krb5_rc4_setup_seq_key(kctx, cipher, cksum);
> -	if (code)
> -		goto out;
> -
> -	plain = kmalloc(8, GFP_NOFS);
> -	if (!plain) {
> -		code = -ENOMEM;
> -		goto out;
> -	}
> -
> -	code = krb5_decrypt(cipher, cksum, buf, plain, 8);
> -	if (code)
> -		goto out_plain;
> -
> -	if ((plain[4] != plain[5]) || (plain[4] != plain[6])
> -				   || (plain[4] != plain[7])) {
> -		code = (s32)KG_BAD_SEQ;
> -		goto out_plain;
> -	}
> -
> -	*direction = plain[4];
> -
> -	*seqnum = ((plain[0] << 24) | (plain[1] << 16) |
> -					(plain[2] << 8) | (plain[3]));
> -out_plain:
> -	kfree(plain);
> -out:
> -	crypto_free_sync_skcipher(cipher);
> -	return code;
> -}
> -
>  s32
>  krb5_get_seq_num(struct krb5_ctx *kctx,
>  	       unsigned char *cksum,
> @@ -164,9 +80,6 @@ krb5_get_seq_num(struct krb5_ctx *kctx,
>  
>  	dprintk("RPC:       krb5_get_seq_num:\n");
>  
> -	if (kctx->enctype == ENCTYPE_ARCFOUR_HMAC)
> -		return krb5_get_rc4_seq_num(kctx, cksum, buf,
> -					    direction, seqnum);
>  	plain = kmalloc(8, GFP_NOFS);
>  	if (!plain)
>  		return -ENOMEM;
> diff --git a/net/sunrpc/auth_gss/gss_krb5_unseal.c b/net/sunrpc/auth_gss/gss_krb5_unseal.c
> index aaab91cf24c8..ba04e3ec970a 100644
> --- a/net/sunrpc/auth_gss/gss_krb5_unseal.c
> +++ b/net/sunrpc/auth_gss/gss_krb5_unseal.c
> @@ -218,7 +218,6 @@ gss_verify_mic_kerberos(struct gss_ctx *gss_ctx,
>  		BUG();
>  	case ENCTYPE_DES_CBC_RAW:
>  	case ENCTYPE_DES3_CBC_RAW:
> -	case ENCTYPE_ARCFOUR_HMAC:
>  		return gss_verify_mic_v1(ctx, message_buffer, read_token);
>  	case ENCTYPE_AES128_CTS_HMAC_SHA1_96:
>  	case ENCTYPE_AES256_CTS_HMAC_SHA1_96:
> diff --git a/net/sunrpc/auth_gss/gss_krb5_wrap.c b/net/sunrpc/auth_gss/gss_krb5_wrap.c
> index cf0fd170ac18..a412a734ee17 100644
> --- a/net/sunrpc/auth_gss/gss_krb5_wrap.c
> +++ b/net/sunrpc/auth_gss/gss_krb5_wrap.c
> @@ -236,26 +236,9 @@ gss_wrap_kerberos_v1(struct krb5_ctx *kctx, int offset,
>  			       seq_send, ptr + GSS_KRB5_TOK_HDR_LEN, ptr + 8)))
>  		return GSS_S_FAILURE;
>  
> -	if (kctx->enctype == ENCTYPE_ARCFOUR_HMAC) {
> -		struct crypto_sync_skcipher *cipher;
> -		int err;
> -		cipher = crypto_alloc_sync_skcipher(kctx->gk5e->encrypt_name,
> -						    0, 0);
> -		if (IS_ERR(cipher))
> -			return GSS_S_FAILURE;
> -
> -		krb5_rc4_setup_enc_key(kctx, cipher, seq_send);
> -
> -		err = gss_encrypt_xdr_buf(cipher, buf,
> -					  offset + headlen - conflen, pages);
> -		crypto_free_sync_skcipher(cipher);
> -		if (err)
> -			return GSS_S_FAILURE;
> -	} else {
> -		if (gss_encrypt_xdr_buf(kctx->enc, buf,
> -					offset + headlen - conflen, pages))
> -			return GSS_S_FAILURE;
> -	}
> +	if (gss_encrypt_xdr_buf(kctx->enc, buf,
> +				offset + headlen - conflen, pages))
> +		return GSS_S_FAILURE;
>  
>  	return (kctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE;
>  }
> @@ -316,37 +299,9 @@ gss_unwrap_kerberos_v1(struct krb5_ctx *kctx, int offset, int len,
>  	crypt_offset = ptr + (GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength) -
>  					(unsigned char *)buf->head[0].iov_base;
>  
> -	/*
> -	 * Need plaintext seqnum to derive encryption key for arcfour-hmac
> -	 */
> -	if (krb5_get_seq_num(kctx, ptr + GSS_KRB5_TOK_HDR_LEN,
> -			     ptr + 8, &direction, &seqnum))
> -		return GSS_S_BAD_SIG;
> -
> -	if ((kctx->initiate && direction != 0xff) ||
> -	    (!kctx->initiate && direction != 0))
> -		return GSS_S_BAD_SIG;
> -
>  	buf->len = len;
> -	if (kctx->enctype == ENCTYPE_ARCFOUR_HMAC) {
> -		struct crypto_sync_skcipher *cipher;
> -		int err;
> -
> -		cipher = crypto_alloc_sync_skcipher(kctx->gk5e->encrypt_name,
> -						    0, 0);
> -		if (IS_ERR(cipher))
> -			return GSS_S_FAILURE;
> -
> -		krb5_rc4_setup_enc_key(kctx, cipher, seqnum);
> -
> -		err = gss_decrypt_xdr_buf(cipher, buf, crypt_offset);
> -		crypto_free_sync_skcipher(cipher);
> -		if (err)
> -			return GSS_S_DEFECTIVE_TOKEN;
> -	} else {
> -		if (gss_decrypt_xdr_buf(kctx->enc, buf, crypt_offset))
> -			return GSS_S_DEFECTIVE_TOKEN;
> -	}
> +	if (gss_decrypt_xdr_buf(kctx->enc, buf, crypt_offset))
> +		return GSS_S_DEFECTIVE_TOKEN;
>  
>  	if (kctx->gk5e->keyed_cksum)
>  		cksumkey = kctx->cksum;
> @@ -370,6 +325,14 @@ gss_unwrap_kerberos_v1(struct krb5_ctx *kctx, int offset, int len,
>  
>  	/* do sequencing checks */
>  
> +	if (krb5_get_seq_num(kctx, ptr + GSS_KRB5_TOK_HDR_LEN,
> +			     ptr + 8, &direction, &seqnum))
> +		return GSS_S_BAD_SIG;
> +
> +	if ((kctx->initiate && direction != 0xff) ||
> +	    (!kctx->initiate && direction != 0))
> +		return GSS_S_BAD_SIG;
> +
>  	/* Copy the data back to the right position.  XXX: Would probably be
>  	 * better to copy and encrypt at the same time. */
>  
> @@ -605,7 +568,6 @@ gss_wrap_kerberos(struct gss_ctx *gctx, int offset,
>  		BUG();
>  	case ENCTYPE_DES_CBC_RAW:
>  	case ENCTYPE_DES3_CBC_RAW:
> -	case ENCTYPE_ARCFOUR_HMAC:
>  		return gss_wrap_kerberos_v1(kctx, offset, buf, pages);
>  	case ENCTYPE_AES128_CTS_HMAC_SHA1_96:
>  	case ENCTYPE_AES256_CTS_HMAC_SHA1_96:
> @@ -624,7 +586,6 @@ gss_unwrap_kerberos(struct gss_ctx *gctx, int offset,
>  		BUG();
>  	case ENCTYPE_DES_CBC_RAW:
>  	case ENCTYPE_DES3_CBC_RAW:
> -	case ENCTYPE_ARCFOUR_HMAC:
>  		return gss_unwrap_kerberos_v1(kctx, offset, len, buf,
>  					      &gctx->slack, &gctx->align);
>  	case ENCTYPE_AES128_CTS_HMAC_SHA1_96:
> -- 
> 2.17.1
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