Initial import

1 files changed, 1161 insertions, 0 deletions

diff --git a/net/rxrpc/rxkad.c b/net/rxrpc/rxkad.c
new file mode 100644
index 000000000..f226709eb
--- /dev/null
+++ b/net/rxrpc/rxkad.c
@@ -0,0 +1,1161 @@
+/* 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.
+ */
+
+#include <linux/module.h>
+#include <linux/net.h>
+#include <linux/skbuff.h>
+#include <linux/udp.h>
+#include <linux/crypto.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>
+#define rxrpc_debug rxkad_debug
+#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 */
+
+unsigned int rxrpc_debug;
+module_param_named(debug, rxrpc_debug, uint, S_IWUSR | S_IRUGO);
+MODULE_PARM_DESC(debug, "rxkad debugging mask");
+
+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 */
+};
+
+MODULE_DESCRIPTION("RxRPC network protocol type-2 security (Kerberos 4)");
+MODULE_AUTHOR("Red Hat, Inc.");
+MODULE_LICENSE("GPL");
+
+/*
+ * 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_blkcipher *rxkad_ci;
+static DEFINE_MUTEX(rxkad_ci_mutex);
+
+/*
+ * initialise connection security
+ */
+static int rxkad_init_connection_security(struct rxrpc_connection *conn)
+{
+	struct crypto_blkcipher *ci;
+	struct rxrpc_key_token *token;
+	int ret;
+
+	_enter("{%d},{%x}", conn->debug_id, key_serial(conn->key));
+
+	token = conn->key->payload.data;
+	conn->security_ix = token->security_index;
+
+	ci = crypto_alloc_blkcipher("pcbc(fcrypt)", 0, CRYPTO_ALG_ASYNC);
+	if (IS_ERR(ci)) {
+		_debug("no cipher");
+		ret = PTR_ERR(ci);
+		goto error;
+	}
+
+	if (crypto_blkcipher_setkey(ci, token->kad->session_key,
+				    sizeof(token->kad->session_key)) < 0)
+		BUG();
+
+	switch (conn->security_level) {
+	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
+ */
+static void rxkad_prime_packet_security(struct rxrpc_connection *conn)
+{
+	struct rxrpc_key_token *token;
+	struct blkcipher_desc desc;
+	struct scatterlist sg[2];
+	struct rxrpc_crypt iv;
+	struct {
+		__be32 x[4];
+	} tmpbuf __attribute__((aligned(16))); /* must all be in same page */
+
+	_enter("");
+
+	if (!conn->key)
+		return;
+
+	token = conn->key->payload.data;
+	memcpy(&iv, token->kad->session_key, sizeof(iv));
+
+	desc.tfm = conn->cipher;
+	desc.info = iv.x;
+	desc.flags = 0;
+
+	tmpbuf.x[0] = conn->epoch;
+	tmpbuf.x[1] = conn->cid;
+	tmpbuf.x[2] = 0;
+	tmpbuf.x[3] = htonl(conn->security_ix);
+
+	sg_init_one(&sg[0], &tmpbuf, sizeof(tmpbuf));
+	sg_init_one(&sg[1], &tmpbuf, sizeof(tmpbuf));
+	crypto_blkcipher_encrypt_iv(&desc, &sg[0], &sg[1], sizeof(tmpbuf));
+
+	memcpy(&conn->csum_iv, &tmpbuf.x[2], sizeof(conn->csum_iv));
+	ASSERTCMP(conn->csum_iv.n[0], ==, tmpbuf.x[2]);
+
+	_leave("");
+}
+
+/*
+ * 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;
+	struct blkcipher_desc desc;
+	struct rxrpc_crypt iv;
+	struct scatterlist sg[2];
+	struct {
+		struct rxkad_level1_hdr hdr;
+		__be32	first;	/* first four bytes of data and padding */
+	} tmpbuf __attribute__((aligned(8))); /* must all be in same page */
+	u16 check;
+
+	sp = rxrpc_skb(skb);
+
+	_enter("");
+
+	check = ntohl(sp->hdr.seq ^ sp->hdr.callNumber);
+	data_size |= (u32) check << 16;
+
+	tmpbuf.hdr.data_size = htonl(data_size);
+	memcpy(&tmpbuf.first, sechdr + 4, sizeof(tmpbuf.first));
+
+	/* start the encryption afresh */
+	memset(&iv, 0, sizeof(iv));
+	desc.tfm = call->conn->cipher;
+	desc.info = iv.x;
+	desc.flags = 0;
+
+	sg_init_one(&sg[0], &tmpbuf, sizeof(tmpbuf));
+	sg_init_one(&sg[1], &tmpbuf, sizeof(tmpbuf));
+	crypto_blkcipher_encrypt_iv(&desc, &sg[0], &sg[1], sizeof(tmpbuf));
+
+	memcpy(sechdr, &tmpbuf, sizeof(tmpbuf));
+
+	_leave(" = 0");
+	return 0;
+}
+
+/*
+ * 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
+		__attribute__((aligned(8))); /* must be all on one page */
+	struct rxrpc_skb_priv *sp;
+	struct blkcipher_desc desc;
+	struct rxrpc_crypt iv;
+	struct scatterlist sg[16];
+	struct sk_buff *trailer;
+	unsigned int len;
+	u16 check;
+	int nsg;
+
+	sp = rxrpc_skb(skb);
+
+	_enter("");
+
+	check = ntohl(sp->hdr.seq ^ sp->hdr.callNumber);
+
+	rxkhdr.data_size = htonl(data_size | (u32) check << 16);
+	rxkhdr.checksum = 0;
+
+	/* encrypt from the session key */
+	token = call->conn->key->payload.data;
+	memcpy(&iv, token->kad->session_key, sizeof(iv));
+	desc.tfm = call->conn->cipher;
+	desc.info = iv.x;
+	desc.flags = 0;
+
+	sg_init_one(&sg[0], sechdr, sizeof(rxkhdr));
+	sg_init_one(&sg[1], &rxkhdr, sizeof(rxkhdr));
+	crypto_blkcipher_encrypt_iv(&desc, &sg[0], &sg[1], sizeof(rxkhdr));
+
+	/* we want to encrypt the skbuff in-place */
+	nsg = skb_cow_data(skb, 0, &trailer);
+	if (nsg < 0 || nsg > 16)
+		return -ENOMEM;
+
+	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);
+	crypto_blkcipher_encrypt_iv(&desc, sg, sg, len);
+
+	_leave(" = 0");
+	return 0;
+}
+
+/*
+ * checksum an RxRPC packet header
+ */
+static int rxkad_secure_packet(const struct rxrpc_call *call,
+				struct sk_buff *skb,
+				size_t data_size,
+				void *sechdr)
+{
+	struct rxrpc_skb_priv *sp;
+	struct blkcipher_desc desc;
+	struct rxrpc_crypt iv;
+	struct scatterlist sg[2];
+	struct {
+		__be32 x[2];
+	} tmpbuf __attribute__((aligned(8))); /* must all be in same page */
+	__be32 x;
+	u32 y;
+	int ret;
+
+	sp = rxrpc_skb(skb);
+
+	_enter("{%d{%x}},{#%u},%zu,",
+	       call->debug_id, key_serial(call->conn->key), ntohl(sp->hdr.seq),
+	       data_size);
+
+	if (!call->conn->cipher)
+		return 0;
+
+	ret = key_validate(call->conn->key);
+	if (ret < 0)
+		return ret;
+
+	/* continue encrypting from where we left off */
+	memcpy(&iv, call->conn->csum_iv.x, sizeof(iv));
+	desc.tfm = call->conn->cipher;
+	desc.info = iv.x;
+	desc.flags = 0;
+
+	/* calculate the security checksum */
+	x = htonl(call->channel << (32 - RXRPC_CIDSHIFT));
+	x |= sp->hdr.seq & cpu_to_be32(0x3fffffff);
+	tmpbuf.x[0] = sp->hdr.callNumber;
+	tmpbuf.x[1] = x;
+
+	sg_init_one(&sg[0], &tmpbuf, sizeof(tmpbuf));
+	sg_init_one(&sg[1], &tmpbuf, sizeof(tmpbuf));
+	crypto_blkcipher_encrypt_iv(&desc, &sg[0], &sg[1], sizeof(tmpbuf));
+
+	y = ntohl(tmpbuf.x[1]);
+	y = (y >> 16) & 0xffff;
+	if (y == 0)
+		y = 1; /* zero checksums are not permitted */
+	sp->hdr.cksum = htons(y);
+
+	switch (call->conn->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;
+}
+
+/*
+ * decrypt partial encryption on a packet (level 1 security)
+ */
+static int rxkad_verify_packet_auth(const struct rxrpc_call *call,
+				    struct sk_buff *skb,
+				    u32 *_abort_code)
+{
+	struct rxkad_level1_hdr sechdr;
+	struct rxrpc_skb_priv *sp;
+	struct blkcipher_desc desc;
+	struct rxrpc_crypt iv;
+	struct scatterlist sg[16];
+	struct sk_buff *trailer;
+	u32 data_size, buf;
+	u16 check;
+	int nsg;
+
+	_enter("");
+
+	sp = rxrpc_skb(skb);
+
+	/* we want to decrypt the skbuff in-place */
+	nsg = skb_cow_data(skb, 0, &trailer);
+	if (nsg < 0 || nsg > 16)
+		goto nomem;
+
+	sg_init_table(sg, nsg);
+	skb_to_sgvec(skb, sg, 0, 8);
+
+	/* start the decryption afresh */
+	memset(&iv, 0, sizeof(iv));
+	desc.tfm = call->conn->cipher;
+	desc.info = iv.x;
+	desc.flags = 0;
+
+	crypto_blkcipher_decrypt_iv(&desc, sg, sg, 8);
+
+	/* remove the decrypted packet length */
+	if (skb_copy_bits(skb, 0, &sechdr, sizeof(sechdr)) < 0)
+		goto datalen_error;
+	if (!skb_pull(skb, sizeof(sechdr)))
+		BUG();
+
+	buf = ntohl(sechdr.data_size);
+	data_size = buf & 0xffff;
+
+	check = buf >> 16;
+	check ^= ntohl(sp->hdr.seq ^ sp->hdr.callNumber);
+	check &= 0xffff;
+	if (check != 0) {
+		*_abort_code = RXKADSEALEDINCON;
+		goto protocol_error;
+	}
+
+	/* shorten the packet to remove the padding */
+	if (data_size > skb->len)
+		goto datalen_error;
+	else if (data_size < skb->len)
+		skb->len = data_size;
+
+	_leave(" = 0 [dlen=%x]", data_size);
+	return 0;
+
+datalen_error:
+	*_abort_code = RXKADDATALEN;
+protocol_error:
+	_leave(" = -EPROTO");
+	return -EPROTO;
+
+nomem:
+	_leave(" = -ENOMEM");
+	return -ENOMEM;
+}
+
+/*
+ * wholly decrypt a packet (level 2 security)
+ */
+static int rxkad_verify_packet_encrypt(const struct rxrpc_call *call,
+				       struct sk_buff *skb,
+				       u32 *_abort_code)
+{
+	const struct rxrpc_key_token *token;
+	struct rxkad_level2_hdr sechdr;
+	struct rxrpc_skb_priv *sp;
+	struct blkcipher_desc desc;
+	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);
+
+	sp = rxrpc_skb(skb);
+
+	/* 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;
+	}
+
+	sg_init_table(sg, nsg);
+	skb_to_sgvec(skb, sg, 0, skb->len);
+
+	/* decrypt from the session key */
+	token = call->conn->key->payload.data;
+	memcpy(&iv, token->kad->session_key, sizeof(iv));
+	desc.tfm = call->conn->cipher;
+	desc.info = iv.x;
+	desc.flags = 0;
+
+	crypto_blkcipher_decrypt_iv(&desc, sg, sg, skb->len);
+	if (sg != _sg)
+		kfree(sg);
+
+	/* remove the decrypted packet length */
+	if (skb_copy_bits(skb, 0, &sechdr, sizeof(sechdr)) < 0)
+		goto datalen_error;
+	if (!skb_pull(skb, sizeof(sechdr)))
+		BUG();
+
+	buf = ntohl(sechdr.data_size);
+	data_size = buf & 0xffff;
+
+	check = buf >> 16;
+	check ^= ntohl(sp->hdr.seq ^ sp->hdr.callNumber);
+	check &= 0xffff;
+	if (check != 0) {
+		*_abort_code = RXKADSEALEDINCON;
+		goto protocol_error;
+	}
+
+	/* shorten the packet to remove the padding */
+	if (data_size > skb->len)
+		goto datalen_error;
+	else if (data_size < skb->len)
+		skb->len = data_size;
+
+	_leave(" = 0 [dlen=%x]", data_size);
+	return 0;
+
+datalen_error:
+	*_abort_code = RXKADDATALEN;
+protocol_error:
+	_leave(" = -EPROTO");
+	return -EPROTO;
+
+nomem:
+	_leave(" = -ENOMEM");
+	return -ENOMEM;
+}
+
+/*
+ * verify the security on a received packet
+ */
+static int rxkad_verify_packet(const struct rxrpc_call *call,
+			       struct sk_buff *skb,
+			       u32 *_abort_code)
+{
+	struct blkcipher_desc desc;
+	struct rxrpc_skb_priv *sp;
+	struct rxrpc_crypt iv;
+	struct scatterlist sg[2];
+	struct {
+		__be32 x[2];
+	} tmpbuf __attribute__((aligned(8))); /* must all be in same page */
+	__be32 x;
+	__be16 cksum;
+	u32 y;
+	int ret;
+
+	sp = rxrpc_skb(skb);
+
+	_enter("{%d{%x}},{#%u}",
+	       call->debug_id, key_serial(call->conn->key),
+	       ntohl(sp->hdr.seq));
+
+	if (!call->conn->cipher)
+		return 0;
+
+	if (sp->hdr.securityIndex != RXRPC_SECURITY_RXKAD) {
+		*_abort_code = RXKADINCONSISTENCY;
+		_leave(" = -EPROTO [not rxkad]");
+		return -EPROTO;
+	}
+
+	/* continue encrypting from where we left off */
+	memcpy(&iv, call->conn->csum_iv.x, sizeof(iv));
+	desc.tfm = call->conn->cipher;
+	desc.info = iv.x;
+	desc.flags = 0;
+
+	/* validate the security checksum */
+	x = htonl(call->channel << (32 - RXRPC_CIDSHIFT));
+	x |= sp->hdr.seq & cpu_to_be32(0x3fffffff);
+	tmpbuf.x[0] = call->call_id;
+	tmpbuf.x[1] = x;
+
+	sg_init_one(&sg[0], &tmpbuf, sizeof(tmpbuf));
+	sg_init_one(&sg[1], &tmpbuf, sizeof(tmpbuf));
+	crypto_blkcipher_encrypt_iv(&desc, &sg[0], &sg[1], sizeof(tmpbuf));
+
+	y = ntohl(tmpbuf.x[1]);
+	y = (y >> 16) & 0xffff;
+	if (y == 0)
+		y = 1; /* zero checksums are not permitted */
+
+	cksum = htons(y);
+	if (sp->hdr.cksum != cksum) {
+		*_abort_code = RXKADSEALEDINCON;
+		_leave(" = -EPROTO [csum failed]");
+		return -EPROTO;
+	}
+
+	switch (call->conn->security_level) {
+	case RXRPC_SECURITY_PLAIN:
+		ret = 0;
+		break;
+	case RXRPC_SECURITY_AUTH:
+		ret = rxkad_verify_packet_auth(call, skb, _abort_code);
+		break;
+	case RXRPC_SECURITY_ENCRYPT:
+		ret = rxkad_verify_packet_encrypt(call, skb, _abort_code);
+		break;
+	default:
+		ret = -ENOANO;
+		break;
+	}
+
+	_leave(" = %d", ret);
+	return ret;
+}
+
+/*
+ * issue a challenge
+ */
+static int rxkad_issue_challenge(struct rxrpc_connection *conn)
+{
+	struct rxkad_challenge challenge;
+	struct rxrpc_header hdr;
+	struct msghdr msg;
+	struct kvec iov[2];
+	size_t len;
+	int ret;
+
+	_enter("{%d,%x}", conn->debug_id, key_serial(conn->key));
+
+	ret = key_validate(conn->key);
+	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;
+
+	msg.msg_name	= &conn->trans->peer->srx.transport.sin;
+	msg.msg_namelen	= sizeof(conn->trans->peer->srx.transport.sin);
+	msg.msg_control	= NULL;
+	msg.msg_controllen = 0;
+	msg.msg_flags	= 0;
+
+	hdr.epoch	= conn->epoch;
+	hdr.cid		= conn->cid;
+	hdr.callNumber	= 0;
+	hdr.seq		= 0;
+	hdr.type	= RXRPC_PACKET_TYPE_CHALLENGE;
+	hdr.flags	= conn->out_clientflag;
+	hdr.userStatus	= 0;
+	hdr.securityIndex = conn->security_ix;
+	hdr._rsvd	= 0;
+	hdr.serviceId	= conn->service_id;
+
+	iov[0].iov_base	= &hdr;
+	iov[0].iov_len	= sizeof(hdr);
+	iov[1].iov_base	= &challenge;
+	iov[1].iov_len	= sizeof(challenge);
+
+	len = iov[0].iov_len + iov[1].iov_len;
+
+	hdr.serial = htonl(atomic_inc_return(&conn->serial));
+	_proto("Tx CHALLENGE %%%u", ntohl(hdr.serial));
+
+	ret = kernel_sendmsg(conn->trans->local->socket, &msg, iov, 2, len);
+	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,
+			       struct rxrpc_header *hdr,
+			       struct rxkad_response *resp,
+			       const struct rxkad_key *s2)
+{
+	struct msghdr msg;
+	struct kvec iov[3];
+	size_t len;
+	int ret;
+
+	_enter("");
+
+	msg.msg_name	= &conn->trans->peer->srx.transport.sin;
+	msg.msg_namelen	= sizeof(conn->trans->peer->srx.transport.sin);
+	msg.msg_control	= NULL;
+	msg.msg_controllen = 0;
+	msg.msg_flags	= 0;
+
+	hdr->epoch	= conn->epoch;
+	hdr->seq	= 0;
+	hdr->type	= RXRPC_PACKET_TYPE_RESPONSE;
+	hdr->flags	= conn->out_clientflag;
+	hdr->userStatus	= 0;
+	hdr->_rsvd	= 0;
+
+	iov[0].iov_base	= hdr;
+	iov[0].iov_len	= sizeof(*hdr);
+	iov[1].iov_base	= resp;
+	iov[1].iov_len	= sizeof(*resp);
+	iov[2].iov_base	= (void *) s2->ticket;
+	iov[2].iov_len	= s2->ticket_len;
+
+	len = iov[0].iov_len + iov[1].iov_len + iov[2].iov_len;
+
+	hdr->serial = htonl(atomic_inc_return(&conn->serial));
+	_proto("Tx RESPONSE %%%u", ntohl(hdr->serial));
+
+	ret = kernel_sendmsg(conn->trans->local->socket, &msg, iov, 3, len);
+	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);
+}
+
+/*
+ * load a scatterlist with a potentially split-page buffer
+ */
+static void rxkad_sg_set_buf2(struct scatterlist sg[2],
+			      void *buf, size_t buflen)
+{
+	int nsg = 1;
+
+	sg_init_table(sg, 2);
+
+	sg_set_buf(&sg[0], buf, buflen);
+	if (sg[0].offset + buflen > PAGE_SIZE) {
+		/* the buffer was split over two pages */
+		sg[0].length = PAGE_SIZE - sg[0].offset;
+		sg_set_buf(&sg[1], buf + sg[0].length, buflen - sg[0].length);
+		nsg++;
+	}
+
+	sg_mark_end(&sg[nsg - 1]);
+
+	ASSERTCMP(sg[0].length + sg[1].length, ==, buflen);
+}
+
+/*
+ * encrypt the response packet
+ */
+static void rxkad_encrypt_response(struct rxrpc_connection *conn,
+				   struct rxkad_response *resp,
+				   const struct rxkad_key *s2)
+{
+	struct blkcipher_desc desc;
+	struct rxrpc_crypt iv;
+	struct scatterlist sg[2];
+
+	/* continue encrypting from where we left off */
+	memcpy(&iv, s2->session_key, sizeof(iv));
+	desc.tfm = conn->cipher;
+	desc.info = iv.x;
+	desc.flags = 0;
+
+	rxkad_sg_set_buf2(sg, &resp->encrypted, sizeof(resp->encrypted));
+	crypto_blkcipher_encrypt_iv(&desc, sg, sg, sizeof(resp->encrypted));
+}
+
+/*
+ * respond to a challenge packet
+ */
+static int rxkad_respond_to_challenge(struct rxrpc_connection *conn,
+				      struct sk_buff *skb,
+				      u32 *_abort_code)
+{
+	const struct rxrpc_key_token *token;
+	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;
+
+	_enter("{%d,%x}", conn->debug_id, key_serial(conn->key));
+
+	if (!conn->key) {
+		_leave(" = -EPROTO [no key]");
+		return -EPROTO;
+	}
+
+	ret = key_validate(conn->key);
+	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 }",
+	       ntohl(sp->hdr.serial), version, nonce, min_level);
+
+	abort_code = RXKADINCONSISTENCY;
+	if (version != RXKAD_VERSION)
+		goto protocol_error;
+
+	abort_code = RXKADLEVELFAIL;
+	if (conn->security_level < min_level)
+		goto protocol_error;
+
+	token = conn->key->payload.data;
+
+	/* build the response packet */
+	memset(&resp, 0, sizeof(resp));
+
+	resp.version = RXKAD_VERSION;
+	resp.encrypted.epoch = conn->epoch;
+	resp.encrypted.cid = conn->cid;
+	resp.encrypted.securityIndex = htonl(conn->security_ix);
+	resp.encrypted.call_id[0] =
+		(conn->channels[0] ? conn->channels[0]->call_id : 0);
+	resp.encrypted.call_id[1] =
+		(conn->channels[1] ? conn->channels[1]->call_id : 0);
+	resp.encrypted.call_id[2] =
+		(conn->channels[2] ? conn->channels[2]->call_id : 0);
+	resp.encrypted.call_id[3] =
+		(conn->channels[3] ? conn->channels[3]->call_id : 0);
+	resp.encrypted.inc_nonce = htonl(nonce + 1);
+	resp.encrypted.level = htonl(conn->security_level);
+	resp.kvno = htonl(token->kad->kvno);
+	resp.ticket_len = htonl(token->kad->ticket_len);
+
+	/* calculate the response checksum and then do the encryption */
+	rxkad_calc_response_checksum(&resp);
+	rxkad_encrypt_response(conn, &resp, token->kad);
+	return rxkad_send_response(conn, &sp->hdr, &resp, token->kad);
+
+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)
+{
+	struct blkcipher_desc desc;
+	struct rxrpc_crypt iv, key;
+	struct scatterlist sg[1];
+	struct in_addr addr;
+	unsigned int life;
+	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;
+		}
+	}
+
+	ASSERT(conn->server_key->payload.data != NULL);
+	ASSERTCMP((unsigned long) ticket & 7UL, ==, 0);
+
+	memcpy(&iv, &conn->server_key->type_data, sizeof(iv));
+
+	desc.tfm = conn->server_key->payload.data;
+	desc.info = iv.x;
+	desc.flags = 0;
+
+	sg_init_one(&sg[0], ticket, ticket_len);
+	crypto_blkcipher_decrypt_iv(&desc, sg, sg, ticket_len);
+
+	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;
+	_debug("KIV ADDR : %pI4", &addr);
+
+	/* 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;
+	now = get_seconds();
+	_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)
+{
+	struct blkcipher_desc desc;
+	struct scatterlist sg[2];
+	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);
+	if (crypto_blkcipher_setkey(rxkad_ci, session_key->x,
+				    sizeof(*session_key)) < 0)
+		BUG();
+
+	memcpy(&iv, session_key, sizeof(iv));
+	desc.tfm = rxkad_ci;
+	desc.info = iv.x;
+	desc.flags = 0;
+
+	rxkad_sg_set_buf2(sg, &resp->encrypted, sizeof(resp->encrypted));
+	crypto_blkcipher_decrypt_iv(&desc, sg, sg, sizeof(resp->encrypted));
+	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;
+	u32 abort_code, version, kvno, ticket_len, level;
+	__be32 csum;
+	int ret;
+
+	_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 }",
+	       ntohl(sp->hdr.serial), version, kvno, ticket_len);
+
+	abort_code = RXKADINCONSISTENCY;
+	if (version != RXKAD_VERSION)
+		goto protocol_error;
+
+	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;
+	if (response.encrypted.epoch != conn->epoch)
+		goto protocol_error_free;
+	if (response.encrypted.cid != conn->cid)
+		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;
+
+	if (ntohl(response.encrypted.call_id[0]) > INT_MAX ||
+	    ntohl(response.encrypted.call_id[1]) > INT_MAX ||
+	    ntohl(response.encrypted.call_id[2]) > INT_MAX ||
+	    ntohl(response.encrypted.call_id[3]) > INT_MAX)
+		goto protocol_error_free;
+
+	abort_code = RXKADOUTOFSEQUENCE;
+	if (response.encrypted.inc_nonce != htonl(conn->security_nonce + 1))
+		goto protocol_error_free;
+
+	abort_code = RXKADLEVELFAIL;
+	level = ntohl(response.encrypted.level);
+	if (level > RXRPC_SECURITY_ENCRYPT)
+		goto protocol_error_free;
+	conn->security_level = level;
+
+	/* 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;
+
+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)
+		crypto_free_blkcipher(conn->cipher);
+}
+
+/*
+ * RxRPC Kerberos-based security
+ */
+static struct rxrpc_security rxkad = {
+	.owner				= THIS_MODULE,
+	.name				= "rxkad",
+	.security_index			= RXRPC_SECURITY_RXKAD,
+	.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,
+};
+
+static __init int rxkad_init(void)
+{
+	_enter("");
+
+	/* pin the cipher we need so that the crypto layer doesn't invoke
+	 * keventd to go get it */
+	rxkad_ci = crypto_alloc_blkcipher("pcbc(fcrypt)", 0, CRYPTO_ALG_ASYNC);
+	if (IS_ERR(rxkad_ci))
+		return PTR_ERR(rxkad_ci);
+
+	return rxrpc_register_security(&rxkad);
+}
+
+module_init(rxkad_init);
+
+static __exit void rxkad_exit(void)
+{
+	_enter("");
+
+	rxrpc_unregister_security(&rxkad);
+	crypto_free_blkcipher(rxkad_ci);
+}
+
+module_exit(rxkad_exit);