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/* SPDX-License-Identifier: GPL-2.0-or-later */
/* Common bits for GSSAPI-based RxRPC security.
*
* Copyright (C) 2025 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*/
#include <crypto/krb5.h>
#include <crypto/skcipher.h>
#include <crypto/hash.h>
/*
* Per-key number context. This is replaced when the connection is rekeyed.
*/
struct rxgk_context {
refcount_t usage;
unsigned int key_number; /* Rekeying number (goes in the rx header) */
unsigned long flags;
#define RXGK_TK_NEEDS_REKEY 0 /* Set if this needs rekeying */
unsigned long expiry; /* Expiration time of this key */
long long bytes_remaining; /* Remaining Tx lifetime of this key */
const struct krb5_enctype *krb5; /* RxGK encryption type */
const struct rxgk_key *key;
/* We need up to 7 keys derived from the transport key, but we don't
* actually need the transport key. Each key is derived by
* DK(TK,constant).
*/
struct crypto_aead *tx_enc; /* Transmission key */
struct crypto_aead *rx_enc; /* Reception key */
struct crypto_shash *tx_Kc; /* Transmission checksum key */
struct crypto_shash *rx_Kc; /* Reception checksum key */
struct crypto_aead *resp_enc; /* Response packet enc key */
};
#define xdr_round_up(x) (round_up((x), sizeof(__be32)))
#define xdr_object_len(x) (4 + xdr_round_up(x))
/*
* rxgk_app.c
*/
int rxgk_yfs_decode_ticket(struct rxrpc_connection *conn, struct sk_buff *skb,
unsigned int ticket_offset, unsigned int ticket_len,
struct key **_key);
int rxgk_extract_token(struct rxrpc_connection *conn, struct sk_buff *skb,
unsigned int token_offset, unsigned int token_len,
struct key **_key);
/*
* rxgk_kdf.c
*/
void rxgk_put(struct rxgk_context *gk);
struct rxgk_context *rxgk_generate_transport_key(struct rxrpc_connection *conn,
const struct rxgk_key *key,
unsigned int key_number,
gfp_t gfp);
int rxgk_set_up_token_cipher(const struct krb5_buffer *server_key,
struct crypto_aead **token_key,
unsigned int enctype,
const struct krb5_enctype **_krb5,
gfp_t gfp);
/*
* Apply decryption and checksumming functions to part of an skbuff. The
* offset and length are updated to reflect the actual content of the encrypted
* region.
*/
static inline
int rxgk_decrypt_skb(const struct krb5_enctype *krb5,
struct crypto_aead *aead,
struct sk_buff *skb,
unsigned int *_offset, unsigned int *_len,
int *_error_code)
{
struct scatterlist sg[16];
size_t offset = 0, len = *_len;
int nr_sg, ret;
sg_init_table(sg, ARRAY_SIZE(sg));
nr_sg = skb_to_sgvec(skb, sg, *_offset, len);
if (unlikely(nr_sg < 0))
return nr_sg;
ret = crypto_krb5_decrypt(krb5, aead, sg, nr_sg,
&offset, &len);
switch (ret) {
case 0:
*_offset += offset;
*_len = len;
break;
case -EBADMSG: /* Checksum mismatch. */
case -EPROTO:
*_error_code = RXGK_SEALEDINCON;
break;
case -EMSGSIZE:
*_error_code = RXGK_PACKETSHORT;
break;
case -ENOPKG: /* Would prefer RXGK_BADETYPE, but not available for YFS. */
default:
*_error_code = RXGK_INCONSISTENCY;
break;
}
return ret;
}
/*
* Check the MIC on a region of an skbuff. The offset and length are updated
* to reflect the actual content of the secure region.
*/
static inline
int rxgk_verify_mic_skb(const struct krb5_enctype *krb5,
struct crypto_shash *shash,
const struct krb5_buffer *metadata,
struct sk_buff *skb,
unsigned int *_offset, unsigned int *_len,
u32 *_error_code)
{
struct scatterlist sg[16];
size_t offset = 0, len = *_len;
int nr_sg, ret;
sg_init_table(sg, ARRAY_SIZE(sg));
nr_sg = skb_to_sgvec(skb, sg, *_offset, len);
if (unlikely(nr_sg < 0))
return nr_sg;
ret = crypto_krb5_verify_mic(krb5, shash, metadata, sg, nr_sg,
&offset, &len);
switch (ret) {
case 0:
*_offset += offset;
*_len = len;
break;
case -EBADMSG: /* Checksum mismatch */
case -EPROTO:
*_error_code = RXGK_SEALEDINCON;
break;
case -EMSGSIZE:
*_error_code = RXGK_PACKETSHORT;
break;
case -ENOPKG: /* Would prefer RXGK_BADETYPE, but not available for YFS. */
default:
*_error_code = RXGK_INCONSISTENCY;
break;
}
return ret;
}
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