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linux/net/rxrpc/rxkad.c
David Howells a1399f8bb0 rxrpc: Call channels should have separate call number spaces 
Each channel on a connection has a separate, independent number space from
which to allocate callNumber values.  It is entirely possible, for example,
to have a connection with four active calls, each with call number 1.

Note that the callNumber values for any particular channel don't have to
start at 1, but they are supposed to increment monotonically for that
channel from a client's perspective and may not be reused once the call
number is transmitted (until the epoch cycles all the way back round).

Currently, however, call numbers are allocated on a per-connection basis
and, further, are held in an rb-tree.  The rb-tree is redundant as the four
channel pointers in the rxrpc_connection struct are entirely capable of
pointing to all the calls currently in progress on a connection.

To this end, make the following changes:

 (1) Handle call number allocation independently per channel.

 (2) Get rid of the conn->calls rb-tree.  This is overkill as a connection
     may have a maximum of four calls in progress at any one time.  Use the
     pointers in the channels[] array instead, indexed by the channel
     number from the packet.

 (3) For each channel, save the result of the last call that was in
     progress on that channel in conn->channels[] so that the final ACK or
     ABORT packet can be replayed if necessary.  Any call earlier than that
     is just ignored.  If we've seen the next call number in a packet, the
     last one is most definitely defunct.

 (4) When generating a RESPONSE packet for a connection, the call number
     counter for each channel must be included in it.

 (5) When parsing a RESPONSE packet for a connection, the call number
     counters contained therein should be used to set the minimum expected
     call numbers on each channel.

To do in future commits:

 (1) Replay terminal packets based on the last call stored in
     conn->channels[].

 (2) Connections should be retired before the callNumber space on any
     channel runs out.

 (3) A server is expected to disregard or reject any new incoming call that
     has a call number less than the current call number counter.  The call
     number counter for that channel must be advanced to the new call
     number.

     Note that the server cannot just require that the next call that it
     sees on a channel be exactly the call number counter + 1 because then
     there's a scenario that could cause a problem: The client transmits a
     packet to initiate a connection, the network goes out, the server
     sends an ACK (which gets lost), the client sends an ABORT (which also
     gets lost); the network then reconnects, the client then reuses the
     call number for the next call (it doesn't know the server already saw
     the call number), but the server thinks it already has the first
     packet of this call (it doesn't know that the client doesn't know that
     it saw the call number the first time).

Signed-off-by: David Howells <dhowells@redhat.com>
2016-07-06 10:43:52 +01:00

1155 lines
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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.
*/
#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);
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 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;
}
/*
* 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 ^ sp->hdr.callNumber;
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;
}
/*
* 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 ^ sp->hdr.callNumber;
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;
}
/*
* 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->channel << (32 - RXRPC_CIDSHIFT);
x |= sp->hdr.seq & 0x3fffffff;
call->crypto_buf[0] = htonl(sp->hdr.callNumber);
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;
}
/*
* 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;
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("");
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));
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);
/* 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 ^= 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;
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);
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->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, skb->len, iv.x);
crypto_skcipher_decrypt(req);
skcipher_request_zero(req);
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 ^= 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(struct rxrpc_call *call,
struct sk_buff *skb,
u32 *_abort_code)
{
SKCIPHER_REQUEST_ON_STACK(req, call->conn->cipher);
struct rxrpc_skb_priv *sp;
struct rxrpc_crypt iv;
struct scatterlist sg;
u16 cksum;
u32 x, y;
int ret;
sp = rxrpc_skb(skb);
_enter("{%d{%x}},{#%u}",
call->debug_id, key_serial(call->conn->params.key), 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));
/* validate the security checksum */
x = call->channel << (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]);
cksum = (y >> 16) & 0xffff;
if (cksum == 0)
cksum = 1; /* zero checksums are not permitted */
if (sp->hdr.cksum != cksum) {
*_abort_code = RXKADSEALEDINCON;
_leave(" = -EPROTO [csum failed]");
return -EPROTO;
}
switch (call->conn->params.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_wire_header whdr;
struct msghdr msg;
struct kvec iov[2];
size_t len;
u32 serial;
int ret;
_enter("{%d,%x}", conn->debug_id, key_serial(conn->params.key));
ret = key_validate(conn->params.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->params.peer->srx.transport.sin;
msg.msg_namelen = sizeof(conn->params.peer->srx.transport.sin);
msg.msg_control = NULL;
msg.msg_controllen = 0;
msg.msg_flags = 0;
whdr.epoch = htonl(conn->proto.epoch);
whdr.cid = htonl(conn->proto.cid);
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;
whdr.serviceId = htons(conn->params.service_id);
iov[0].iov_base = &whdr;
iov[0].iov_len = sizeof(whdr);
iov[1].iov_base = &challenge;
iov[1].iov_len = sizeof(challenge);
len = iov[0].iov_len + iov[1].iov_len;
serial = atomic_inc_return(&conn->serial);
whdr.serial = htonl(serial);
_proto("Tx CHALLENGE %%%u", serial);
ret = kernel_sendmsg(conn->params.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_host_header *hdr,
struct rxkad_response *resp,
const struct rxkad_key *s2)
{
struct rxrpc_wire_header whdr;
struct msghdr msg;
struct kvec iov[3];
size_t len;
u32 serial;
int ret;
_enter("");
msg.msg_name = &conn->params.peer->srx.transport.sin;
msg.msg_namelen = sizeof(conn->params.peer->srx.transport.sin);
msg.msg_control = NULL;
msg.msg_controllen = 0;
msg.msg_flags = 0;
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);
iov[0].iov_base = &whdr;
iov[0].iov_len = sizeof(whdr);
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;
serial = atomic_inc_return(&conn->serial);
whdr.serial = htonl(serial);
_proto("Tx RESPONSE %%%u", serial);
ret = kernel_sendmsg(conn->params.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);
}
/*
* encrypt the response packet
*/
static void rxkad_encrypt_response(struct rxrpc_connection *conn,
struct rxkad_response *resp,
const struct rxkad_key *s2)
{
SKCIPHER_REQUEST_ON_STACK(req, conn->cipher);
struct rxrpc_crypt iv;
struct scatterlist sg[1];
/* continue encrypting from where we left off */
memcpy(&iv, s2->session_key, sizeof(iv));
sg_init_table(sg, 1);
sg_set_buf(sg, &resp->encrypted, sizeof(resp->encrypted));
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);
}
/*
* 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->params.key));
if (!conn->params.key) {
_leave(" = -EPROTO [no key]");
return -EPROTO;
}
ret = key_validate(conn->params.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 }",
sp->hdr.serial, version, nonce, min_level);
abort_code = RXKADINCONSISTENCY;
if (version != RXKAD_VERSION)
goto protocol_error;
abort_code = RXKADLEVELFAIL;
if (conn->params.security_level < min_level)
goto protocol_error;
token = conn->params.key->payload.data[0];
/* build the response packet */
memset(&resp, 0, sizeof(resp));
resp.version = htonl(RXKAD_VERSION);
resp.encrypted.epoch = htonl(conn->proto.epoch);
resp.encrypted.cid = htonl(conn->proto.cid);
resp.encrypted.securityIndex = htonl(conn->security_ix);
resp.encrypted.inc_nonce = htonl(nonce + 1);
resp.encrypted.level = htonl(conn->params.security_level);
resp.kvno = htonl(token->kad->kvno);
resp.ticket_len = htonl(token->kad->ticket_len);
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);
/* 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 skcipher_request *req;
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[0] != NULL);
ASSERTCMP((unsigned long) ticket & 7UL, ==, 0);
memcpy(&iv, &conn->server_key->payload.data[2], sizeof(iv));
req = skcipher_request_alloc(conn->server_key->payload.data[0],
GFP_NOFS);
if (!req) {
*_abort_code = RXKADNOAUTH;
ret = -ENOMEM;
goto error;
}
sg_init_one(&sg[0], ticket, ticket_len);
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);
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)
{
SKCIPHER_REQUEST_ON_STACK(req, rxkad_ci);
struct scatterlist sg[1];
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_skcipher_setkey(rxkad_ci, session_key->x,
sizeof(*session_key)) < 0)
BUG();
memcpy(&iv, session_key, sizeof(iv));
sg_init_table(sg, 1);
sg_set_buf(sg, &resp->encrypted, sizeof(resp->encrypted));
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);
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, i;
_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 }",
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 (ntohl(response.encrypted.epoch) != conn->proto.epoch)
goto protocol_error_free;
if (ntohl(response.encrypted.cid) != conn->proto.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;
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);
abort_code = RXKADOUTOFSEQUENCE;
if (ntohl(response.encrypted.inc_nonce) != 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->params.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_unlock:
spin_unlock(&conn->channel_lock);
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_skcipher(conn->cipher);
}
/*
* 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);
return PTR_ERR_OR_ZERO(rxkad_ci);
}
/*
* Clean up the rxkad security service.
*/
static void rxkad_exit(void)
{
if (rxkad_ci)
crypto_free_skcipher(rxkad_ci);
}
/*
* RxRPC Kerberos-based security
*/
const struct rxrpc_security rxkad = {
.name = "rxkad",
.security_index = RXRPC_SECURITY_RXKAD,
.init = rxkad_init,
.exit = rxkad_exit,
.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,
};
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