rxkad.c 27.9 KB
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/* Kerberos-based RxRPC security
 *
 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

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#include <crypto/skcipher.h>
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#include <linux/module.h>
#include <linux/net.h>
#include <linux/skbuff.h>
#include <linux/udp.h>
#include <linux/scatterlist.h>
#include <linux/ctype.h>
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#include <linux/slab.h>
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#include <net/sock.h>
#include <net/af_rxrpc.h>
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#include <keys/rxrpc-type.h>
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#include "ar-internal.h"

#define RXKAD_VERSION			2
#define MAXKRB5TICKETLEN		1024
#define RXKAD_TKT_TYPE_KERBEROS_V5	256
#define ANAME_SZ			40	/* size of authentication name */
#define INST_SZ				40	/* size of principal's instance */
#define REALM_SZ			40	/* size of principal's auth domain */
#define SNAME_SZ			40	/* size of service name */

struct rxkad_level1_hdr {
	__be32	data_size;	/* true data size (excluding padding) */
};

struct rxkad_level2_hdr {
	__be32	data_size;	/* true data size (excluding padding) */
	__be32	checksum;	/* decrypted data checksum */
};

/*
 * this holds a pinned cipher so that keventd doesn't get called by the cipher
 * alloc routine, but since we have it to hand, we use it to decrypt RESPONSE
 * packets
 */
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static struct crypto_skcipher *rxkad_ci;
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static DEFINE_MUTEX(rxkad_ci_mutex);

/*
 * initialise connection security
 */
static int rxkad_init_connection_security(struct rxrpc_connection *conn)
{
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	struct crypto_skcipher *ci;
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	struct rxrpc_key_token *token;
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	int ret;

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	_enter("{%d},{%x}", conn->debug_id, key_serial(conn->params.key));
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	token = conn->params.key->payload.data[0];
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	conn->security_ix = token->security_index;
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	ci = crypto_alloc_skcipher("pcbc(fcrypt)", 0, CRYPTO_ALG_ASYNC);
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	if (IS_ERR(ci)) {
		_debug("no cipher");
		ret = PTR_ERR(ci);
		goto error;
	}

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	if (crypto_skcipher_setkey(ci, token->kad->session_key,
				   sizeof(token->kad->session_key)) < 0)
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		BUG();

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	switch (conn->params.security_level) {
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	case RXRPC_SECURITY_PLAIN:
		break;
	case RXRPC_SECURITY_AUTH:
		conn->size_align = 8;
		conn->security_size = sizeof(struct rxkad_level1_hdr);
		conn->header_size += sizeof(struct rxkad_level1_hdr);
		break;
	case RXRPC_SECURITY_ENCRYPT:
		conn->size_align = 8;
		conn->security_size = sizeof(struct rxkad_level2_hdr);
		conn->header_size += sizeof(struct rxkad_level2_hdr);
		break;
	default:
		ret = -EKEYREJECTED;
		goto error;
	}

	conn->cipher = ci;
	ret = 0;
error:
	_leave(" = %d", ret);
	return ret;
}

/*
 * prime the encryption state with the invariant parts of a connection's
 * description
 */
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static int rxkad_prime_packet_security(struct rxrpc_connection *conn)
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{
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	struct rxrpc_key_token *token;
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	SKCIPHER_REQUEST_ON_STACK(req, conn->cipher);
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	struct scatterlist sg;
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	struct rxrpc_crypt iv;
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	__be32 *tmpbuf;
	size_t tmpsize = 4 * sizeof(__be32);
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	_enter("");

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	if (!conn->params.key)
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		return 0;

	tmpbuf = kmalloc(tmpsize, GFP_KERNEL);
	if (!tmpbuf)
		return -ENOMEM;
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	token = conn->params.key->payload.data[0];
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	memcpy(&iv, token->kad->session_key, sizeof(iv));
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	tmpbuf[0] = htonl(conn->proto.epoch);
	tmpbuf[1] = htonl(conn->proto.cid);
	tmpbuf[2] = 0;
	tmpbuf[3] = htonl(conn->security_ix);
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	sg_init_one(&sg, tmpbuf, tmpsize);
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	skcipher_request_set_tfm(req, conn->cipher);
	skcipher_request_set_callback(req, 0, NULL, NULL);
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	skcipher_request_set_crypt(req, &sg, &sg, tmpsize, iv.x);
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	crypto_skcipher_encrypt(req);
	skcipher_request_zero(req);
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	memcpy(&conn->csum_iv, tmpbuf + 2, sizeof(conn->csum_iv));
	kfree(tmpbuf);
	_leave(" = 0");
	return 0;
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}

/*
 * partially encrypt a packet (level 1 security)
 */
static int rxkad_secure_packet_auth(const struct rxrpc_call *call,
				    struct sk_buff *skb,
				    u32 data_size,
				    void *sechdr)
{
	struct rxrpc_skb_priv *sp;
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	SKCIPHER_REQUEST_ON_STACK(req, call->conn->cipher);
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	struct rxkad_level1_hdr hdr;
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	struct rxrpc_crypt iv;
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	struct scatterlist sg;
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	u16 check;

	sp = rxrpc_skb(skb);

	_enter("");

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	check = sp->hdr.seq ^ sp->hdr.callNumber;
	data_size |= (u32)check << 16;
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	hdr.data_size = htonl(data_size);
	memcpy(sechdr, &hdr, sizeof(hdr));
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	/* start the encryption afresh */
	memset(&iv, 0, sizeof(iv));

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	sg_init_one(&sg, sechdr, 8);
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	skcipher_request_set_tfm(req, call->conn->cipher);
	skcipher_request_set_callback(req, 0, NULL, NULL);
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	skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x);
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	crypto_skcipher_encrypt(req);
	skcipher_request_zero(req);
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	_leave(" = 0");
	return 0;
}

/*
 * wholly encrypt a packet (level 2 security)
 */
static int rxkad_secure_packet_encrypt(const struct rxrpc_call *call,
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				       struct sk_buff *skb,
				       u32 data_size,
				       void *sechdr)
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{
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	const struct rxrpc_key_token *token;
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	struct rxkad_level2_hdr rxkhdr;
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	struct rxrpc_skb_priv *sp;
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	SKCIPHER_REQUEST_ON_STACK(req, call->conn->cipher);
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	struct rxrpc_crypt iv;
	struct scatterlist sg[16];
	struct sk_buff *trailer;
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	unsigned int len;
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	u16 check;
	int nsg;
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	int err;
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	sp = rxrpc_skb(skb);

	_enter("");

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	check = sp->hdr.seq ^ sp->hdr.callNumber;
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	rxkhdr.data_size = htonl(data_size | (u32)check << 16);
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	rxkhdr.checksum = 0;
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	memcpy(sechdr, &rxkhdr, sizeof(rxkhdr));
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	/* encrypt from the session key */
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	token = call->conn->params.key->payload.data[0];
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	memcpy(&iv, token->kad->session_key, sizeof(iv));
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	sg_init_one(&sg[0], sechdr, sizeof(rxkhdr));
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	skcipher_request_set_tfm(req, call->conn->cipher);
	skcipher_request_set_callback(req, 0, NULL, NULL);
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	skcipher_request_set_crypt(req, &sg[0], &sg[0], sizeof(rxkhdr), iv.x);
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	crypto_skcipher_encrypt(req);
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	/* we want to encrypt the skbuff in-place */
	nsg = skb_cow_data(skb, 0, &trailer);
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	err = -ENOMEM;
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	if (nsg < 0 || nsg > 16)
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		goto out;
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	len = data_size + call->conn->size_align - 1;
	len &= ~(call->conn->size_align - 1);

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	sg_init_table(sg, nsg);
	skb_to_sgvec(skb, sg, 0, len);
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	skcipher_request_set_crypt(req, sg, sg, len, iv.x);
	crypto_skcipher_encrypt(req);
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	_leave(" = 0");
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	err = 0;

out:
	skcipher_request_zero(req);
	return err;
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}

/*
 * checksum an RxRPC packet header
 */
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static int rxkad_secure_packet(struct rxrpc_call *call,
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			       struct sk_buff *skb,
			       size_t data_size,
			       void *sechdr)
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{
	struct rxrpc_skb_priv *sp;
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	SKCIPHER_REQUEST_ON_STACK(req, call->conn->cipher);
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	struct rxrpc_crypt iv;
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	struct scatterlist sg;
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	u32 x, y;
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	int ret;

	sp = rxrpc_skb(skb);

	_enter("{%d{%x}},{#%u},%zu,",
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	       call->debug_id, key_serial(call->conn->params.key),
	       sp->hdr.seq, data_size);
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	if (!call->conn->cipher)
		return 0;

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	ret = key_validate(call->conn->params.key);
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	if (ret < 0)
		return ret;

	/* continue encrypting from where we left off */
	memcpy(&iv, call->conn->csum_iv.x, sizeof(iv));

	/* calculate the security checksum */
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	x = (call->cid & RXRPC_CHANNELMASK) << (32 - RXRPC_CIDSHIFT);
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	x |= sp->hdr.seq & 0x3fffffff;
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	call->crypto_buf[0] = htonl(sp->hdr.callNumber);
	call->crypto_buf[1] = htonl(x);
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	sg_init_one(&sg, call->crypto_buf, 8);
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	skcipher_request_set_tfm(req, call->conn->cipher);
	skcipher_request_set_callback(req, 0, NULL, NULL);
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	skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x);
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	crypto_skcipher_encrypt(req);
	skcipher_request_zero(req);
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	y = ntohl(call->crypto_buf[1]);
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	y = (y >> 16) & 0xffff;
	if (y == 0)
		y = 1; /* zero checksums are not permitted */
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	sp->hdr.cksum = y;
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	switch (call->conn->params.security_level) {
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	case RXRPC_SECURITY_PLAIN:
		ret = 0;
		break;
	case RXRPC_SECURITY_AUTH:
		ret = rxkad_secure_packet_auth(call, skb, data_size, sechdr);
		break;
	case RXRPC_SECURITY_ENCRYPT:
		ret = rxkad_secure_packet_encrypt(call, skb, data_size,
						  sechdr);
		break;
	default:
		ret = -EPERM;
		break;
	}

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	_leave(" = %d [set %hx]", ret, y);
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	return ret;
}

/*
 * decrypt partial encryption on a packet (level 1 security)
 */
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static int rxkad_verify_packet_1(struct rxrpc_call *call, struct sk_buff *skb,
				 rxrpc_seq_t seq)
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{
	struct rxkad_level1_hdr sechdr;
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	SKCIPHER_REQUEST_ON_STACK(req, call->conn->cipher);
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	struct rxrpc_crypt iv;
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	struct scatterlist sg[16];
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	struct sk_buff *trailer;
	u32 data_size, buf;
	u16 check;
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	int nsg;
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	_enter("");

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	if (skb->len < 8) {
		rxrpc_abort_call("V1H", call, seq, RXKADSEALEDINCON, EPROTO);
		goto protocol_error;
	}
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	/* we want to decrypt the skbuff in-place */
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	nsg = skb_cow_data(skb, 0, &trailer);
	if (nsg < 0 || nsg > 16)
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		goto nomem;

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	sg_init_table(sg, nsg);
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	skb_to_sgvec(skb, sg, 0, 8);
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	/* start the decryption afresh */
	memset(&iv, 0, sizeof(iv));

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	skcipher_request_set_tfm(req, call->conn->cipher);
	skcipher_request_set_callback(req, 0, NULL, NULL);
	skcipher_request_set_crypt(req, sg, sg, 8, iv.x);
	crypto_skcipher_decrypt(req);
	skcipher_request_zero(req);
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	/* Extract the decrypted packet length */
	if (skb_copy_bits(skb, 0, &sechdr, sizeof(sechdr)) < 0) {
		rxrpc_abort_call("XV1", call, seq, RXKADDATALEN, EPROTO);
		goto protocol_error;
	}
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	if (!skb_pull(skb, sizeof(sechdr)))
		BUG();

	buf = ntohl(sechdr.data_size);
	data_size = buf & 0xffff;

	check = buf >> 16;
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	check ^= seq ^ call->call_id;
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	check &= 0xffff;
	if (check != 0) {
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		rxrpc_abort_call("V1C", call, seq, RXKADSEALEDINCON, EPROTO);
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		goto protocol_error;
	}

	/* shorten the packet to remove the padding */
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	if (data_size > skb->len) {
		rxrpc_abort_call("V1L", call, seq, RXKADDATALEN, EPROTO);
		goto protocol_error;
	}
	if (data_size < skb->len)
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		skb->len = data_size;

	_leave(" = 0 [dlen=%x]", data_size);
	return 0;

protocol_error:
	_leave(" = -EPROTO");
	return -EPROTO;

nomem:
	_leave(" = -ENOMEM");
	return -ENOMEM;
}

/*
 * wholly decrypt a packet (level 2 security)
 */
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static int rxkad_verify_packet_2(struct rxrpc_call *call, struct sk_buff *skb,
				 rxrpc_seq_t seq)
399
{
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	const struct rxrpc_key_token *token;
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	struct rxkad_level2_hdr sechdr;
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	SKCIPHER_REQUEST_ON_STACK(req, call->conn->cipher);
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	struct rxrpc_crypt iv;
	struct scatterlist _sg[4], *sg;
	struct sk_buff *trailer;
	u32 data_size, buf;
	u16 check;
	int nsg;

	_enter(",{%d}", skb->len);

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	if (skb->len < 8) {
		rxrpc_abort_call("V2H", call, seq, RXKADSEALEDINCON, EPROTO);
		goto protocol_error;
	}
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	/* we want to decrypt the skbuff in-place */
	nsg = skb_cow_data(skb, 0, &trailer);
	if (nsg < 0)
		goto nomem;

	sg = _sg;
	if (unlikely(nsg > 4)) {
		sg = kmalloc(sizeof(*sg) * nsg, GFP_NOIO);
		if (!sg)
			goto nomem;
	}

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	sg_init_table(sg, nsg);
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	skb_to_sgvec(skb, sg, 0, skb->len);
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	/* decrypt from the session key */
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	token = call->conn->params.key->payload.data[0];
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	memcpy(&iv, token->kad->session_key, sizeof(iv));
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	skcipher_request_set_tfm(req, call->conn->cipher);
	skcipher_request_set_callback(req, 0, NULL, NULL);
	skcipher_request_set_crypt(req, sg, sg, skb->len, iv.x);
	crypto_skcipher_decrypt(req);
	skcipher_request_zero(req);
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	if (sg != _sg)
		kfree(sg);

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	/* Extract the decrypted packet length */
	if (skb_copy_bits(skb, 0, &sechdr, sizeof(sechdr)) < 0) {
		rxrpc_abort_call("XV2", call, seq, RXKADDATALEN, EPROTO);
		goto protocol_error;
	}
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	if (!skb_pull(skb, sizeof(sechdr)))
		BUG();

	buf = ntohl(sechdr.data_size);
	data_size = buf & 0xffff;

	check = buf >> 16;
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	check ^= seq ^ call->call_id;
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	check &= 0xffff;
	if (check != 0) {
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		rxrpc_abort_call("V2C", call, seq, RXKADSEALEDINCON, EPROTO);
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		goto protocol_error;
	}

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	if (data_size > skb->len) {
		rxrpc_abort_call("V2L", call, seq, RXKADDATALEN, EPROTO);
		goto protocol_error;
	}
	if (data_size < skb->len)
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		skb->len = data_size;

	_leave(" = 0 [dlen=%x]", data_size);
	return 0;

protocol_error:
	_leave(" = -EPROTO");
	return -EPROTO;

nomem:
	_leave(" = -ENOMEM");
	return -ENOMEM;
}

/*
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 * Verify the security on a received packet or subpacket (if part of a
 * jumbo packet).
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 */
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static int rxkad_verify_packet(struct rxrpc_call *call, struct sk_buff *skb,
			       rxrpc_seq_t seq, u16 expected_cksum)
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{
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	SKCIPHER_REQUEST_ON_STACK(req, call->conn->cipher);
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	struct rxrpc_crypt iv;
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	struct scatterlist sg;
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	u16 cksum;
	u32 x, y;
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	_enter("{%d{%x}},{#%u}",
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	       call->debug_id, key_serial(call->conn->params.key), seq);
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	if (!call->conn->cipher)
		return 0;

	/* continue encrypting from where we left off */
	memcpy(&iv, call->conn->csum_iv.x, sizeof(iv));

	/* validate the security checksum */
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	x = (call->cid & RXRPC_CHANNELMASK) << (32 - RXRPC_CIDSHIFT);
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	x |= seq & 0x3fffffff;
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	call->crypto_buf[0] = htonl(call->call_id);
	call->crypto_buf[1] = htonl(x);
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	sg_init_one(&sg, call->crypto_buf, 8);
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	skcipher_request_set_tfm(req, call->conn->cipher);
	skcipher_request_set_callback(req, 0, NULL, NULL);
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	skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x);
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	crypto_skcipher_encrypt(req);
	skcipher_request_zero(req);
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	y = ntohl(call->crypto_buf[1]);
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	cksum = (y >> 16) & 0xffff;
	if (cksum == 0)
		cksum = 1; /* zero checksums are not permitted */
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	if (cksum != expected_cksum) {
		rxrpc_abort_call("VCK", call, seq, RXKADSEALEDINCON, EPROTO);
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		_leave(" = -EPROTO [csum failed]");
		return -EPROTO;
	}

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	switch (call->conn->params.security_level) {
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	case RXRPC_SECURITY_PLAIN:
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		return 0;
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	case RXRPC_SECURITY_AUTH:
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		return rxkad_verify_packet_1(call, skb, seq);
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	case RXRPC_SECURITY_ENCRYPT:
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		return rxkad_verify_packet_2(call, skb, seq);
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	default:
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		return -ENOANO;
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	}
}

/*
 * issue a challenge
 */
static int rxkad_issue_challenge(struct rxrpc_connection *conn)
{
	struct rxkad_challenge challenge;
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	struct rxrpc_wire_header whdr;
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	struct msghdr msg;
	struct kvec iov[2];
	size_t len;
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	u32 serial;
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	int ret;

553
	_enter("{%d,%x}", conn->debug_id, key_serial(conn->params.key));
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	ret = key_validate(conn->params.key);
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	if (ret < 0)
		return ret;

	get_random_bytes(&conn->security_nonce, sizeof(conn->security_nonce));

	challenge.version	= htonl(2);
	challenge.nonce		= htonl(conn->security_nonce);
	challenge.min_level	= htonl(0);
	challenge.__padding	= 0;

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	msg.msg_name	= &conn->params.peer->srx.transport.sin;
	msg.msg_namelen	= sizeof(conn->params.peer->srx.transport.sin);
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	msg.msg_control	= NULL;
	msg.msg_controllen = 0;
	msg.msg_flags	= 0;

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	whdr.epoch	= htonl(conn->proto.epoch);
	whdr.cid	= htonl(conn->proto.cid);
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	whdr.callNumber	= 0;
	whdr.seq	= 0;
	whdr.type	= RXRPC_PACKET_TYPE_CHALLENGE;
	whdr.flags	= conn->out_clientflag;
	whdr.userStatus	= 0;
	whdr.securityIndex = conn->security_ix;
	whdr._rsvd	= 0;
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	whdr.serviceId	= htons(conn->params.service_id);
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	iov[0].iov_base	= &whdr;
	iov[0].iov_len	= sizeof(whdr);
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	iov[1].iov_base	= &challenge;
	iov[1].iov_len	= sizeof(challenge);

	len = iov[0].iov_len + iov[1].iov_len;

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	serial = atomic_inc_return(&conn->serial);
	whdr.serial = htonl(serial);
	_proto("Tx CHALLENGE %%%u", serial);
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	ret = kernel_sendmsg(conn->params.local->socket, &msg, iov, 2, len);
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	if (ret < 0) {
		_debug("sendmsg failed: %d", ret);
		return -EAGAIN;
	}

	_leave(" = 0");
	return 0;
}

/*
 * send a Kerberos security response
 */
static int rxkad_send_response(struct rxrpc_connection *conn,
608
			       struct rxrpc_host_header *hdr,
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			       struct rxkad_response *resp,
			       const struct rxkad_key *s2)
{
612
	struct rxrpc_wire_header whdr;
613 614 615
	struct msghdr msg;
	struct kvec iov[3];
	size_t len;
616
	u32 serial;
617 618 619 620
	int ret;

	_enter("");

621 622
	msg.msg_name	= &conn->params.peer->srx.transport.sin;
	msg.msg_namelen	= sizeof(conn->params.peer->srx.transport.sin);
623 624 625 626
	msg.msg_control	= NULL;
	msg.msg_controllen = 0;
	msg.msg_flags	= 0;

627 628 629 630 631 632 633
	memset(&whdr, 0, sizeof(whdr));
	whdr.epoch	= htonl(hdr->epoch);
	whdr.cid	= htonl(hdr->cid);
	whdr.type	= RXRPC_PACKET_TYPE_RESPONSE;
	whdr.flags	= conn->out_clientflag;
	whdr.securityIndex = hdr->securityIndex;
	whdr.serviceId	= htons(hdr->serviceId);
634

635 636
	iov[0].iov_base	= &whdr;
	iov[0].iov_len	= sizeof(whdr);
637 638
	iov[1].iov_base	= resp;
	iov[1].iov_len	= sizeof(*resp);
639
	iov[2].iov_base	= (void *)s2->ticket;
640 641 642 643
	iov[2].iov_len	= s2->ticket_len;

	len = iov[0].iov_len + iov[1].iov_len + iov[2].iov_len;

644 645 646
	serial = atomic_inc_return(&conn->serial);
	whdr.serial = htonl(serial);
	_proto("Tx RESPONSE %%%u", serial);
647

648
	ret = kernel_sendmsg(conn->params.local->socket, &msg, iov, 3, len);
649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679
	if (ret < 0) {
		_debug("sendmsg failed: %d", ret);
		return -EAGAIN;
	}

	_leave(" = 0");
	return 0;
}

/*
 * calculate the response checksum
 */
static void rxkad_calc_response_checksum(struct rxkad_response *response)
{
	u32 csum = 1000003;
	int loop;
	u8 *p = (u8 *) response;

	for (loop = sizeof(*response); loop > 0; loop--)
		csum = csum * 0x10204081 + *p++;

	response->encrypted.checksum = htonl(csum);
}

/*
 * encrypt the response packet
 */
static void rxkad_encrypt_response(struct rxrpc_connection *conn,
				   struct rxkad_response *resp,
				   const struct rxkad_key *s2)
{
H
Herbert Xu 已提交
680
	SKCIPHER_REQUEST_ON_STACK(req, conn->cipher);
681
	struct rxrpc_crypt iv;
682
	struct scatterlist sg[1];
683 684 685 686

	/* continue encrypting from where we left off */
	memcpy(&iv, s2->session_key, sizeof(iv));

687 688
	sg_init_table(sg, 1);
	sg_set_buf(sg, &resp->encrypted, sizeof(resp->encrypted));
H
Herbert Xu 已提交
689 690 691 692 693
	skcipher_request_set_tfm(req, conn->cipher);
	skcipher_request_set_callback(req, 0, NULL, NULL);
	skcipher_request_set_crypt(req, sg, sg, sizeof(resp->encrypted), iv.x);
	crypto_skcipher_encrypt(req);
	skcipher_request_zero(req);
694 695 696 697 698 699 700 701 702
}

/*
 * respond to a challenge packet
 */
static int rxkad_respond_to_challenge(struct rxrpc_connection *conn,
				      struct sk_buff *skb,
				      u32 *_abort_code)
{
703
	const struct rxrpc_key_token *token;
704 705 706 707 708 709 710
	struct rxkad_challenge challenge;
	struct rxkad_response resp
		__attribute__((aligned(8))); /* must be aligned for crypto */
	struct rxrpc_skb_priv *sp;
	u32 version, nonce, min_level, abort_code;
	int ret;

711
	_enter("{%d,%x}", conn->debug_id, key_serial(conn->params.key));
712

713
	if (!conn->params.key) {
714 715 716 717
		_leave(" = -EPROTO [no key]");
		return -EPROTO;
	}

718
	ret = key_validate(conn->params.key);
719 720 721 722 723 724 725 726 727 728 729 730 731 732 733
	if (ret < 0) {
		*_abort_code = RXKADEXPIRED;
		return ret;
	}

	abort_code = RXKADPACKETSHORT;
	sp = rxrpc_skb(skb);
	if (skb_copy_bits(skb, 0, &challenge, sizeof(challenge)) < 0)
		goto protocol_error;

	version = ntohl(challenge.version);
	nonce = ntohl(challenge.nonce);
	min_level = ntohl(challenge.min_level);

	_proto("Rx CHALLENGE %%%u { v=%u n=%u ml=%u }",
734
	       sp->hdr.serial, version, nonce, min_level);
735 736 737 738 739 740

	abort_code = RXKADINCONSISTENCY;
	if (version != RXKAD_VERSION)
		goto protocol_error;

	abort_code = RXKADLEVELFAIL;
741
	if (conn->params.security_level < min_level)
742 743
		goto protocol_error;

744
	token = conn->params.key->payload.data[0];
745 746 747 748

	/* build the response packet */
	memset(&resp, 0, sizeof(resp));

749
	resp.version			= htonl(RXKAD_VERSION);
750 751
	resp.encrypted.epoch		= htonl(conn->proto.epoch);
	resp.encrypted.cid		= htonl(conn->proto.cid);
752 753
	resp.encrypted.securityIndex	= htonl(conn->security_ix);
	resp.encrypted.inc_nonce	= htonl(nonce + 1);
754
	resp.encrypted.level		= htonl(conn->params.security_level);
755 756 757
	resp.kvno			= htonl(token->kad->kvno);
	resp.ticket_len			= htonl(token->kad->ticket_len);

758 759 760 761
	resp.encrypted.call_id[0] = htonl(conn->channels[0].call_counter);
	resp.encrypted.call_id[1] = htonl(conn->channels[1].call_counter);
	resp.encrypted.call_id[2] = htonl(conn->channels[2].call_counter);
	resp.encrypted.call_id[3] = htonl(conn->channels[3].call_counter);
762 763 764

	/* calculate the response checksum and then do the encryption */
	rxkad_calc_response_checksum(&resp);
765 766
	rxkad_encrypt_response(conn, &resp, token->kad);
	return rxkad_send_response(conn, &sp->hdr, &resp, token->kad);
767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782

protocol_error:
	*_abort_code = abort_code;
	_leave(" = -EPROTO [%d]", abort_code);
	return -EPROTO;
}

/*
 * decrypt the kerberos IV ticket in the response
 */
static int rxkad_decrypt_ticket(struct rxrpc_connection *conn,
				void *ticket, size_t ticket_len,
				struct rxrpc_crypt *_session_key,
				time_t *_expiry,
				u32 *_abort_code)
{
H
Herbert Xu 已提交
783
	struct skcipher_request *req;
784
	struct rxrpc_crypt iv, key;
785
	struct scatterlist sg[1];
786
	struct in_addr addr;
787
	unsigned int life;
788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808
	time_t issue, now;
	bool little_endian;
	int ret;
	u8 *p, *q, *name, *end;

	_enter("{%d},{%x}", conn->debug_id, key_serial(conn->server_key));

	*_expiry = 0;

	ret = key_validate(conn->server_key);
	if (ret < 0) {
		switch (ret) {
		case -EKEYEXPIRED:
			*_abort_code = RXKADEXPIRED;
			goto error;
		default:
			*_abort_code = RXKADNOAUTH;
			goto error;
		}
	}

809
	ASSERT(conn->server_key->payload.data[0] != NULL);
810 811
	ASSERTCMP((unsigned long) ticket & 7UL, ==, 0);

812
	memcpy(&iv, &conn->server_key->payload.data[2], sizeof(iv));
813

H
Herbert Xu 已提交
814 815 816 817 818 819 820
	req = skcipher_request_alloc(conn->server_key->payload.data[0],
				     GFP_NOFS);
	if (!req) {
		*_abort_code = RXKADNOAUTH;
		ret = -ENOMEM;
		goto error;
	}
821

822
	sg_init_one(&sg[0], ticket, ticket_len);
H
Herbert Xu 已提交
823 824 825 826
	skcipher_request_set_callback(req, 0, NULL, NULL);
	skcipher_request_set_crypt(req, sg, sg, ticket_len, iv.x);
	crypto_skcipher_decrypt(req);
	skcipher_request_free(req);
827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866

	p = ticket;
	end = p + ticket_len;

#define Z(size)						\
	({						\
		u8 *__str = p;				\
		q = memchr(p, 0, end - p);		\
		if (!q || q - p > (size))		\
			goto bad_ticket;		\
		for (; p < q; p++)			\
			if (!isprint(*p))		\
				goto bad_ticket;	\
		p++;					\
		__str;					\
	})

	/* extract the ticket flags */
	_debug("KIV FLAGS: %x", *p);
	little_endian = *p & 1;
	p++;

	/* extract the authentication name */
	name = Z(ANAME_SZ);
	_debug("KIV ANAME: %s", name);

	/* extract the principal's instance */
	name = Z(INST_SZ);
	_debug("KIV INST : %s", name);

	/* extract the principal's authentication domain */
	name = Z(REALM_SZ);
	_debug("KIV REALM: %s", name);

	if (end - p < 4 + 8 + 4 + 2)
		goto bad_ticket;

	/* get the IPv4 address of the entity that requested the ticket */
	memcpy(&addr, p, sizeof(addr));
	p += 4;
H
Harvey Harrison 已提交
867
	_debug("KIV ADDR : %pI4", &addr);
868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889

	/* get the session key from the ticket */
	memcpy(&key, p, sizeof(key));
	p += 8;
	_debug("KIV KEY  : %08x %08x", ntohl(key.n[0]), ntohl(key.n[1]));
	memcpy(_session_key, &key, sizeof(key));

	/* get the ticket's lifetime */
	life = *p++ * 5 * 60;
	_debug("KIV LIFE : %u", life);

	/* get the issue time of the ticket */
	if (little_endian) {
		__le32 stamp;
		memcpy(&stamp, p, 4);
		issue = le32_to_cpu(stamp);
	} else {
		__be32 stamp;
		memcpy(&stamp, p, 4);
		issue = be32_to_cpu(stamp);
	}
	p += 4;
890
	now = get_seconds();
891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933
	_debug("KIV ISSUE: %lx [%lx]", issue, now);

	/* check the ticket is in date */
	if (issue > now) {
		*_abort_code = RXKADNOAUTH;
		ret = -EKEYREJECTED;
		goto error;
	}

	if (issue < now - life) {
		*_abort_code = RXKADEXPIRED;
		ret = -EKEYEXPIRED;
		goto error;
	}

	*_expiry = issue + life;

	/* get the service name */
	name = Z(SNAME_SZ);
	_debug("KIV SNAME: %s", name);

	/* get the service instance name */
	name = Z(INST_SZ);
	_debug("KIV SINST: %s", name);

	ret = 0;
error:
	_leave(" = %d", ret);
	return ret;

bad_ticket:
	*_abort_code = RXKADBADTICKET;
	ret = -EBADMSG;
	goto error;
}

/*
 * decrypt the response packet
 */
static void rxkad_decrypt_response(struct rxrpc_connection *conn,
				   struct rxkad_response *resp,
				   const struct rxrpc_crypt *session_key)
{
H
Herbert Xu 已提交
934
	SKCIPHER_REQUEST_ON_STACK(req, rxkad_ci);
935
	struct scatterlist sg[1];
936 937 938 939 940 941 942 943
	struct rxrpc_crypt iv;

	_enter(",,%08x%08x",
	       ntohl(session_key->n[0]), ntohl(session_key->n[1]));

	ASSERT(rxkad_ci != NULL);

	mutex_lock(&rxkad_ci_mutex);
H
Herbert Xu 已提交
944 945
	if (crypto_skcipher_setkey(rxkad_ci, session_key->x,
				   sizeof(*session_key)) < 0)
946 947 948 949
		BUG();

	memcpy(&iv, session_key, sizeof(iv));

950 951
	sg_init_table(sg, 1);
	sg_set_buf(sg, &resp->encrypted, sizeof(resp->encrypted));
H
Herbert Xu 已提交
952 953 954 955 956 957
	skcipher_request_set_tfm(req, rxkad_ci);
	skcipher_request_set_callback(req, 0, NULL, NULL);
	skcipher_request_set_crypt(req, sg, sg, sizeof(resp->encrypted), iv.x);
	crypto_skcipher_decrypt(req);
	skcipher_request_zero(req);

958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975
	mutex_unlock(&rxkad_ci_mutex);

	_leave("");
}

/*
 * verify a response
 */
static int rxkad_verify_response(struct rxrpc_connection *conn,
				 struct sk_buff *skb,
				 u32 *_abort_code)
{
	struct rxkad_response response
		__attribute__((aligned(8))); /* must be aligned for crypto */
	struct rxrpc_skb_priv *sp;
	struct rxrpc_crypt session_key;
	time_t expiry;
	void *ticket;
A
Al Viro 已提交
976 977
	u32 abort_code, version, kvno, ticket_len, level;
	__be32 csum;
978
	int ret, i;
979 980 981 982 983 984 985 986 987 988 989 990 991 992

	_enter("{%d,%x}", conn->debug_id, key_serial(conn->server_key));

	abort_code = RXKADPACKETSHORT;
	if (skb_copy_bits(skb, 0, &response, sizeof(response)) < 0)
		goto protocol_error;
	if (!pskb_pull(skb, sizeof(response)))
		BUG();

	version = ntohl(response.version);
	ticket_len = ntohl(response.ticket_len);
	kvno = ntohl(response.kvno);
	sp = rxrpc_skb(skb);
	_proto("Rx RESPONSE %%%u { v=%u kv=%u tl=%u }",
993
	       sp->hdr.serial, version, kvno, ticket_len);
994 995 996

	abort_code = RXKADINCONSISTENCY;
	if (version != RXKAD_VERSION)
D
David Howells 已提交
997
		goto protocol_error;
998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028

	abort_code = RXKADTICKETLEN;
	if (ticket_len < 4 || ticket_len > MAXKRB5TICKETLEN)
		goto protocol_error;

	abort_code = RXKADUNKNOWNKEY;
	if (kvno >= RXKAD_TKT_TYPE_KERBEROS_V5)
		goto protocol_error;

	/* extract the kerberos ticket and decrypt and decode it */
	ticket = kmalloc(ticket_len, GFP_NOFS);
	if (!ticket)
		return -ENOMEM;

	abort_code = RXKADPACKETSHORT;
	if (skb_copy_bits(skb, 0, ticket, ticket_len) < 0)
		goto protocol_error_free;

	ret = rxkad_decrypt_ticket(conn, ticket, ticket_len, &session_key,
				   &expiry, &abort_code);
	if (ret < 0) {
		*_abort_code = abort_code;
		kfree(ticket);
		return ret;
	}

	/* use the session key from inside the ticket to decrypt the
	 * response */
	rxkad_decrypt_response(conn, &response, &session_key);

	abort_code = RXKADSEALEDINCON;
1029
	if (ntohl(response.encrypted.epoch) != conn->proto.epoch)
1030
		goto protocol_error_free;
1031
	if (ntohl(response.encrypted.cid) != conn->proto.cid)
1032 1033 1034 1035 1036 1037 1038 1039 1040
		goto protocol_error_free;
	if (ntohl(response.encrypted.securityIndex) != conn->security_ix)
		goto protocol_error_free;
	csum = response.encrypted.checksum;
	response.encrypted.checksum = 0;
	rxkad_calc_response_checksum(&response);
	if (response.encrypted.checksum != csum)
		goto protocol_error_free;

1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060
	spin_lock(&conn->channel_lock);
	for (i = 0; i < RXRPC_MAXCALLS; i++) {
		struct rxrpc_call *call;
		u32 call_id = ntohl(response.encrypted.call_id[i]);

		if (call_id > INT_MAX)
			goto protocol_error_unlock;

		if (call_id < conn->channels[i].call_counter)
			goto protocol_error_unlock;
		if (call_id > conn->channels[i].call_counter) {
			call = rcu_dereference_protected(
				conn->channels[i].call,
				lockdep_is_held(&conn->channel_lock));
			if (call && call->state < RXRPC_CALL_COMPLETE)
				goto protocol_error_unlock;
			conn->channels[i].call_counter = call_id;
		}
	}
	spin_unlock(&conn->channel_lock);
1061 1062

	abort_code = RXKADOUTOFSEQUENCE;
1063
	if (ntohl(response.encrypted.inc_nonce) != conn->security_nonce + 1)
1064 1065 1066 1067 1068 1069
		goto protocol_error_free;

	abort_code = RXKADLEVELFAIL;
	level = ntohl(response.encrypted.level);
	if (level > RXRPC_SECURITY_ENCRYPT)
		goto protocol_error_free;
1070
	conn->params.security_level = level;
1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084

	/* create a key to hold the security data and expiration time - after
	 * this the connection security can be handled in exactly the same way
	 * as for a client connection */
	ret = rxrpc_get_server_data_key(conn, &session_key, expiry, kvno);
	if (ret < 0) {
		kfree(ticket);
		return ret;
	}

	kfree(ticket);
	_leave(" = 0");
	return 0;

1085 1086
protocol_error_unlock:
	spin_unlock(&conn->channel_lock);
1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102
protocol_error_free:
	kfree(ticket);
protocol_error:
	*_abort_code = abort_code;
	_leave(" = -EPROTO [%d]", abort_code);
	return -EPROTO;
}

/*
 * clear the connection security
 */
static void rxkad_clear(struct rxrpc_connection *conn)
{
	_enter("");

	if (conn->cipher)
H
Herbert Xu 已提交
1103
		crypto_free_skcipher(conn->cipher);
1104 1105
}

1106 1107 1108 1109 1110 1111 1112 1113
/*
 * Initialise the rxkad security service.
 */
static int rxkad_init(void)
{
	/* pin the cipher we need so that the crypto layer doesn't invoke
	 * keventd to go get it */
	rxkad_ci = crypto_alloc_skcipher("pcbc(fcrypt)", 0, CRYPTO_ALG_ASYNC);
W
Wu Fengguang 已提交
1114
	return PTR_ERR_OR_ZERO(rxkad_ci);
1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125
}

/*
 * Clean up the rxkad security service.
 */
static void rxkad_exit(void)
{
	if (rxkad_ci)
		crypto_free_skcipher(rxkad_ci);
}

1126 1127 1128
/*
 * RxRPC Kerberos-based security
 */
1129
const struct rxrpc_security rxkad = {
1130
	.name				= "rxkad",
1131
	.security_index			= RXRPC_SECURITY_RXKAD,
1132 1133
	.init				= rxkad_init,
	.exit				= rxkad_exit,
1134 1135 1136 1137 1138 1139 1140 1141 1142
	.init_connection_security	= rxkad_init_connection_security,
	.prime_packet_security		= rxkad_prime_packet_security,
	.secure_packet			= rxkad_secure_packet,
	.verify_packet			= rxkad_verify_packet,
	.issue_challenge		= rxkad_issue_challenge,
	.respond_to_challenge		= rxkad_respond_to_challenge,
	.verify_response		= rxkad_verify_response,
	.clear				= rxkad_clear,
};