Release 4.11 net/rxrpc/rxkad.c

/* 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.
 */


#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

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

static struct crypto_skcipher *rxkad_ci;
static DEFINE_MUTEX(rxkad_ci_mutex);

/*
 * initialise connection security
 */


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

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

	token = conn->params.key->payload.data[0];
	conn->security_ix = token->security_index;

	ci = crypto_alloc_skcipher("pcbc(fcrypt)", 0, CRYPTO_ALG_ASYNC);
	if (IS_ERR(ci)) {
		_debug("no cipher");
		ret = PTR_ERR(ci);
		goto error;
	}

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

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

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

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5
100.00%

/*
 * prime the encryption state with the invariant parts of a connection's
 * description
 */


static int rxkad_prime_packet_security(struct rxrpc_connection *conn)
{
	struct rxrpc_key_token *token;
	SKCIPHER_REQUEST_ON_STACK(req, conn->cipher);
	struct scatterlist sg;
	struct rxrpc_crypt iv;
	__be32 *tmpbuf;
	size_t tmpsize = 4 * sizeof(__be32);

	_enter("");

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

	tmpbuf = kmalloc(tmpsize, GFP_KERNEL);
	if (!tmpbuf)
		return -ENOMEM;

	token = conn->params.key->payload.data[0];
	memcpy(&iv, token->kad->session_key, sizeof(iv));

	tmpbuf[0] = htonl(conn->proto.epoch);
	tmpbuf[1] = htonl(conn->proto.cid);
	tmpbuf[2] = 0;
	tmpbuf[3] = htonl(conn->security_ix);

	sg_init_one(&sg, tmpbuf, tmpsize);
	skcipher_request_set_tfm(req, conn->cipher);
	skcipher_request_set_callback(req, 0, NULL, NULL);
	skcipher_request_set_crypt(req, &sg, &sg, tmpsize, iv.x);
	crypto_skcipher_encrypt(req);
	skcipher_request_zero(req);

	memcpy(&conn->csum_iv, tmpbuf + 2, sizeof(conn->csum_iv));
	kfree(tmpbuf);
	_leave(" = 0");
	return 0;
}

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8
100.00%

/*
 * 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;
	SKCIPHER_REQUEST_ON_STACK(req, call->conn->cipher);
	struct rxkad_level1_hdr hdr;
	struct rxrpc_crypt iv;
	struct scatterlist sg;
	u16 check;

	sp = rxrpc_skb(skb);

	_enter("");

	check = sp->hdr.seq ^ call->call_id;
	data_size |= (u32)check << 16;

	hdr.data_size = htonl(data_size);
	memcpy(sechdr, &hdr, sizeof(hdr));

	/* start the encryption afresh */
	memset(&iv, 0, sizeof(iv));

	sg_init_one(&sg, sechdr, 8);
	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_encrypt(req);
	skcipher_request_zero(req);

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

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3
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191
100.00%
5
100.00%

/*
 * wholly encrypt a packet (level 2 security)
 */


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

	sp = rxrpc_skb(skb);

	_enter("");

	check = sp->hdr.seq ^ call->call_id;

	rxkhdr.data_size = htonl(data_size | (u32)check << 16);
	rxkhdr.checksum = 0;
	memcpy(sechdr, &rxkhdr, sizeof(rxkhdr));

	/* encrypt from the session key */
	token = call->conn->params.key->payload.data[0];
	memcpy(&iv, token->kad->session_key, sizeof(iv));

	sg_init_one(&sg[0], sechdr, sizeof(rxkhdr));
	skcipher_request_set_tfm(req, call->conn->cipher);
	skcipher_request_set_callback(req, 0, NULL, NULL);
	skcipher_request_set_crypt(req, &sg[0], &sg[0], sizeof(rxkhdr), iv.x);
	crypto_skcipher_encrypt(req);

	/* we want to encrypt the skbuff in-place */
	nsg = skb_cow_data(skb, 0, &trailer);
	err = -ENOMEM;
	if (nsg < 0 || nsg > 16)
		goto out;

	len = data_size + call->conn->size_align - 1;
	len &= ~(call->conn->size_align - 1);

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

	_leave(" = 0");
	err = 0;

out:
	skcipher_request_zero(req);
	return err;
}

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27.61%
3
30.00%
David S. Miller
3
0.85%
1
10.00%
Eric Dumazet
1
0.28%
1
10.00%
Total
355
100.00%
10
100.00%

/*
 * checksum an RxRPC packet header
 */


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

	sp = rxrpc_skb(skb);

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

	if (!call->conn->cipher)
		return 0;

	ret = key_validate(call->conn->params.key);
	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 */
	x = (call->cid & RXRPC_CHANNELMASK) << (32 - RXRPC_CIDSHIFT);
	x |= sp->hdr.seq & 0x3fffffff;
	call->crypto_buf[0] = htonl(call->call_id);
	call->crypto_buf[1] = htonl(x);

	sg_init_one(&sg, call->crypto_buf, 8);
	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_encrypt(req);
	skcipher_request_zero(req);

	y = ntohl(call->crypto_buf[1]);
	y = (y >> 16) & 0xffff;
	if (y == 0)
		y = 1; /* zero checksums are not permitted */
	sp->hdr.cksum = y;

	switch (call->conn->params.security_level) {
	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;
	}

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

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17.47%
3
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10
2.69%
1
11.11%
Total
372
100.00%
9
100.00%

/*
 * decrypt partial encryption on a packet (level 1 security)
 */


static int rxkad_verify_packet_1(struct rxrpc_call *call, struct sk_buff *skb,
				 unsigned int offset, unsigned int len,
				 rxrpc_seq_t seq)
{
	struct rxkad_level1_hdr sechdr;
	SKCIPHER_REQUEST_ON_STACK(req, call->conn->cipher);
	struct rxrpc_crypt iv;
	struct scatterlist sg[16];
	struct sk_buff *trailer;
	u32 data_size, buf;
	u16 check;
	int nsg;

	_enter("");

	if (len < 8) {
		rxrpc_abort_call("V1H", call, seq, RXKADSEALEDINCON, EPROTO);
		goto protocol_error;
	}

	/* Decrypt the skbuff in-place.  TODO: We really want to decrypt
         * directly into the target buffer.
         */
	nsg = skb_cow_data(skb, 0, &trailer);
	if (nsg < 0 || nsg > 16)
		goto nomem;

	sg_init_table(sg, nsg);
	skb_to_sgvec(skb, sg, offset, 8);

	/* start the decryption afresh */
	memset(&iv, 0, sizeof(iv));

	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);

	/* Extract the decrypted packet length */
	if (skb_copy_bits(skb, offset, &sechdr, sizeof(sechdr)) < 0) {
		rxrpc_abort_call("XV1", call, seq, RXKADDATALEN, EPROTO);
		goto protocol_error;
	}
	offset += sizeof(sechdr);
	len -= sizeof(sechdr);

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

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

	if (data_size > len) {
		rxrpc_abort_call("V1L", call, seq, RXKADDATALEN, EPROTO);
		goto protocol_error;
	}

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

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

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

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100.00%
6
100.00%

/*
 * wholly decrypt a packet (level 2 security)
 */


static int rxkad_verify_packet_2(struct rxrpc_call *call, struct sk_buff *skb,
				 unsigned int offset, unsigned int len,
				 rxrpc_seq_t seq)
{
	const struct rxrpc_key_token *token;
	struct rxkad_level2_hdr sechdr;
	SKCIPHER_REQUEST_ON_STACK(req, call->conn->cipher);
	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);

	if (len < 8) {
		rxrpc_abort_call("V2H", call, seq, RXKADSEALEDINCON, EPROTO);
		goto protocol_error;
	}

	/* Decrypt the skbuff in-place.  TODO: We really want to decrypt
         * directly into the target buffer.
         */
	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;
	}

	sg_init_table(sg, nsg);
	skb_to_sgvec(skb, sg, offset, len);

	/* decrypt from the session key */
	token = call->conn->params.key->payload.data[0];
	memcpy(&iv, token->kad->session_key, sizeof(iv));

	skcipher_request_set_tfm(req, call->conn->cipher);
	skcipher_request_set_callback(req, 0, NULL, NULL);
	skcipher_request_set_crypt(req, sg, sg, len, iv.x);
	crypto_skcipher_decrypt(req);
	skcipher_request_zero(req);
	if (sg != _sg)
		kfree(sg);

	/* Extract the decrypted packet length */
	if (skb_copy_bits(skb, offset, &sechdr, sizeof(sechdr)) < 0) {
		rxrpc_abort_call("XV2", call, seq, RXKADDATALEN, EPROTO);
		goto protocol_error;
	}
	offset += sizeof(sechdr);
	len -= sizeof(sechdr);

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

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

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

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

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

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

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9
100.00%

/*
 * Verify the security on a received packet or subpacket (if part of a
 * jumbo packet).
 */


static int rxkad_verify_packet(struct rxrpc_call *call, struct sk_buff *skb,
			       unsigned int offset, unsigned int len,
			       rxrpc_seq_t seq, u16 expected_cksum)
{
	SKCIPHER_REQUEST_ON_STACK(req, call->conn->cipher);
	struct rxrpc_crypt iv;
	struct scatterlist sg;
	u16 cksum;
	u32 x, y;

	_enter("{%d{%x}},{#%u}",
	       call->debug_id, key_serial(call->conn->params.key), seq);

	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 */
	x = (call->cid & RXRPC_CHANNELMASK) << (32 - RXRPC_CIDSHIFT);
	x |= seq & 0x3fffffff;
	call->crypto_buf[0] = htonl(call->call_id);
	call->crypto_buf[1] = htonl(x);

	sg_init_one(&sg, call->crypto_buf, 8);
	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_encrypt(req);
	skcipher_request_zero(req);

	y = ntohl(call->crypto_buf[1]);
	cksum = (y >> 16) & 0xffff;
	if (cksum == 0)
		cksum = 1; /* zero checksums are not permitted */

	if (cksum != expected_cksum) {
		rxrpc_abort_call("VCK", call, seq, RXKADSEALEDINCON, EPROTO);
		rxrpc_send_abort_packet(call);
		_leave(" = -EPROTO [csum failed]");
		return -EPROTO;
	}

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

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3
25.00%
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2
0.58%
1
8.33%
Total
346
100.00%
12
100.00%

/*
 * Locate the data contained in a packet that was partially encrypted.
 */


static void rxkad_locate_data_1(struct rxrpc_call *call, struct sk_buff *skb,
				unsigned int *_offset, unsigned int *_len)
{
	struct rxkad_level1_hdr sechdr;

	if (skb_copy_bits(skb, *_offset, &sechdr, sizeof(sechdr)) < 0)
		BUG();
	*_offset += sizeof(sechdr);
	*_len = ntohl(sechdr.data_size) & 0xffff;
}

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/*
 * Locate the data contained in a packet that was completely encrypted.
 */


static void rxkad_locate_data_2(struct rxrpc_call *call, struct sk_buff *skb,
				unsigned int *_offset, unsigned int *_len)
{
	struct rxkad_level2_hdr sechdr;

	if (skb_copy_bits(skb, *_offset, &sechdr, sizeof(sechdr)) < 0)
		BUG();
	*_offset += sizeof(sechdr);
	*_len = ntohl(sechdr.data_size) & 0xffff;
}

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/*
 * Locate the data contained in an already decrypted packet.
 */


static void rxkad_locate_data(struct rxrpc_call *call, struct sk_buff *skb,
			      unsigned int *_offset, unsigned int *_len)
{
	switch (call->conn->params.security_level) {
	case RXRPC_SECURITY_AUTH:
		rxkad_locate_data_1(call, skb, _offset, _len);
		return;
	case RXRPC_SECURITY_ENCRYPT:
		rxkad_locate_data_2(call, skb, _offset, _len);
		return;
	default:
		return;
	}
}

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/*
 * issue a challenge
 */


static int rxkad_issue_challenge(struct rxrpc_connection *conn)
{
	struct rxkad_challenge challenge