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rxkad.c
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rxkad.c
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// SPDX-License-Identifier: GPL-2.0-or-later
/* Kerberos-based RxRPC security
*
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells ([email protected])
*/
#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 <linux/key-type.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 */
#define RXKAD_ALIGN 8
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 */
};
static int rxkad_prime_packet_security(struct rxrpc_connection *conn,
struct crypto_sync_skcipher *ci);
/*
* 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_sync_skcipher *rxkad_ci;
static struct skcipher_request *rxkad_ci_req;
static DEFINE_MUTEX(rxkad_ci_mutex);
/*
* Parse the information from a server key
*
* The data should be the 8-byte secret key.
*/
static int rxkad_preparse_server_key(struct key_preparsed_payload *prep)
{
struct crypto_skcipher *ci;
if (prep->datalen != 8)
return -EINVAL;
memcpy(&prep->payload.data[2], prep->data, 8);
ci = crypto_alloc_skcipher("pcbc(des)", 0, CRYPTO_ALG_ASYNC);
if (IS_ERR(ci)) {
_leave(" = %ld", PTR_ERR(ci));
return PTR_ERR(ci);
}
if (crypto_skcipher_setkey(ci, prep->data, 8) < 0)
BUG();
prep->payload.data[0] = ci;
_leave(" = 0");
return 0;
}
static void rxkad_free_preparse_server_key(struct key_preparsed_payload *prep)
{
if (prep->payload.data[0])
crypto_free_skcipher(prep->payload.data[0]);
}
static void rxkad_destroy_server_key(struct key *key)
{
if (key->payload.data[0]) {
crypto_free_skcipher(key->payload.data[0]);
key->payload.data[0] = NULL;
}
}
/*
* initialise connection security
*/
static int rxkad_init_connection_security(struct rxrpc_connection *conn,
struct rxrpc_key_token *token)
{
struct crypto_sync_skcipher *ci;
int ret;
_enter("{%d},{%x}", conn->debug_id, key_serial(conn->key));
conn->security_ix = token->security_index;
ci = crypto_alloc_sync_skcipher("pcbc(fcrypt)", 0, 0);
if (IS_ERR(ci)) {
_debug("no cipher");
ret = PTR_ERR(ci);
goto error;
}
if (crypto_sync_skcipher_setkey(ci, token->kad->session_key,
sizeof(token->kad->session_key)) < 0)
BUG();
switch (conn->security_level) {
case RXRPC_SECURITY_PLAIN:
case RXRPC_SECURITY_AUTH:
case RXRPC_SECURITY_ENCRYPT:
break;
default:
ret = -EKEYREJECTED;
goto error;
}
ret = rxkad_prime_packet_security(conn, ci);
if (ret < 0)
goto error_ci;
conn->rxkad.cipher = ci;
return 0;
error_ci:
crypto_free_sync_skcipher(ci);
error:
_leave(" = %d", ret);
return ret;
}
/*
* Work out how much data we can put in a packet.
*/
static int rxkad_how_much_data(struct rxrpc_call *call, size_t remain,
size_t *_buf_size, size_t *_data_size, size_t *_offset)
{
size_t shdr, buf_size, chunk;
switch (call->conn->security_level) {
default:
buf_size = chunk = min_t(size_t, remain, RXRPC_JUMBO_DATALEN);
shdr = 0;
goto out;
case RXRPC_SECURITY_AUTH:
shdr = sizeof(struct rxkad_level1_hdr);
break;
case RXRPC_SECURITY_ENCRYPT:
shdr = sizeof(struct rxkad_level2_hdr);
break;
}
buf_size = round_down(RXRPC_JUMBO_DATALEN, RXKAD_ALIGN);
chunk = buf_size - shdr;
if (remain < chunk)
buf_size = round_up(shdr + remain, RXKAD_ALIGN);
out:
*_buf_size = buf_size;
*_data_size = chunk;
*_offset = shdr;
return 0;
}
/*
* prime the encryption state with the invariant parts of a connection's
* description
*/
static int rxkad_prime_packet_security(struct rxrpc_connection *conn,
struct crypto_sync_skcipher *ci)
{
struct skcipher_request *req;
struct rxrpc_key_token *token;
struct scatterlist sg;
struct rxrpc_crypt iv;
__be32 *tmpbuf;
size_t tmpsize = 4 * sizeof(__be32);
_enter("");
if (!conn->key)
return 0;
tmpbuf = kmalloc(tmpsize, GFP_KERNEL);
if (!tmpbuf)
return -ENOMEM;
req = skcipher_request_alloc(&ci->base, GFP_NOFS);
if (!req) {
kfree(tmpbuf);
return -ENOMEM;
}
token = conn->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_sync_tfm(req, ci);
skcipher_request_set_callback(req, 0, NULL, NULL);
skcipher_request_set_crypt(req, &sg, &sg, tmpsize, iv.x);
crypto_skcipher_encrypt(req);
skcipher_request_free(req);
memcpy(&conn->rxkad.csum_iv, tmpbuf + 2, sizeof(conn->rxkad.csum_iv));
kfree(tmpbuf);
_leave(" = 0");
return 0;
}
/*
* Allocate and prepare the crypto request on a call. For any particular call,
* this is called serially for the packets, so no lock should be necessary.
*/
static struct skcipher_request *rxkad_get_call_crypto(struct rxrpc_call *call)
{
struct crypto_skcipher *tfm = &call->conn->rxkad.cipher->base;
return skcipher_request_alloc(tfm, GFP_NOFS);
}
/*
* Clean up the crypto on a call.
*/
static void rxkad_free_call_crypto(struct rxrpc_call *call)
{
}
/*
* partially encrypt a packet (level 1 security)
*/
static int rxkad_secure_packet_auth(const struct rxrpc_call *call,
struct rxrpc_txbuf *txb,
struct skcipher_request *req)
{
struct rxkad_level1_hdr *hdr = (void *)txb->data;
struct rxrpc_crypt iv;
struct scatterlist sg;
size_t pad;
u16 check;
_enter("");
check = txb->seq ^ ntohl(txb->wire.callNumber);
hdr->data_size = htonl((u32)check << 16 | txb->len);
txb->len += sizeof(struct rxkad_level1_hdr);
pad = txb->len;
pad = RXKAD_ALIGN - pad;
pad &= RXKAD_ALIGN - 1;
if (pad) {
memset(txb->data + txb->offset, 0, pad);
txb->len += pad;
}
/* start the encryption afresh */
memset(&iv, 0, sizeof(iv));
sg_init_one(&sg, txb->data, 8);
skcipher_request_set_sync_tfm(req, call->conn->rxkad.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 rxrpc_txbuf *txb,
struct skcipher_request *req)
{
const struct rxrpc_key_token *token;
struct rxkad_level2_hdr *rxkhdr = (void *)txb->data;
struct rxrpc_crypt iv;
struct scatterlist sg;
size_t pad;
u16 check;
int ret;
_enter("");
check = txb->seq ^ ntohl(txb->wire.callNumber);
rxkhdr->data_size = htonl(txb->len | (u32)check << 16);
rxkhdr->checksum = 0;
txb->len += sizeof(struct rxkad_level2_hdr);
pad = txb->len;
pad = RXKAD_ALIGN - pad;
pad &= RXKAD_ALIGN - 1;
if (pad) {
memset(txb->data + txb->offset, 0, pad);
txb->len += pad;
}
/* encrypt from the session key */
token = call->conn->key->payload.data[0];
memcpy(&iv, token->kad->session_key, sizeof(iv));
sg_init_one(&sg, txb->data, txb->len);
skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher);
skcipher_request_set_callback(req, 0, NULL, NULL);
skcipher_request_set_crypt(req, &sg, &sg, txb->len, iv.x);
ret = crypto_skcipher_encrypt(req);
skcipher_request_zero(req);
return ret;
}
/*
* checksum an RxRPC packet header
*/
static int rxkad_secure_packet(struct rxrpc_call *call, struct rxrpc_txbuf *txb)
{
struct skcipher_request *req;
struct rxrpc_crypt iv;
struct scatterlist sg;
union {
__be32 buf[2];
} crypto __aligned(8);
u32 x, y;
int ret;
_enter("{%d{%x}},{#%u},%u,",
call->debug_id, key_serial(call->conn->key),
txb->seq, txb->len);
if (!call->conn->rxkad.cipher)
return 0;
ret = key_validate(call->conn->key);
if (ret < 0)
return ret;
req = rxkad_get_call_crypto(call);
if (!req)
return -ENOMEM;
/* continue encrypting from where we left off */
memcpy(&iv, call->conn->rxkad.csum_iv.x, sizeof(iv));
/* calculate the security checksum */
x = (ntohl(txb->wire.cid) & RXRPC_CHANNELMASK) << (32 - RXRPC_CIDSHIFT);
x |= txb->seq & 0x3fffffff;
crypto.buf[0] = txb->wire.callNumber;
crypto.buf[1] = htonl(x);
sg_init_one(&sg, crypto.buf, 8);
skcipher_request_set_sync_tfm(req, call->conn->rxkad.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(crypto.buf[1]);
y = (y >> 16) & 0xffff;
if (y == 0)
y = 1; /* zero checksums are not permitted */
txb->wire.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, txb, req);
break;
case RXRPC_SECURITY_ENCRYPT:
ret = rxkad_secure_packet_encrypt(call, txb, req);
break;
default:
ret = -EPERM;
break;
}
skcipher_request_free(req);
_leave(" = %d [set %x]", ret, y);
return ret;
}
/*
* decrypt partial encryption on a packet (level 1 security)
*/
static int rxkad_verify_packet_1(struct rxrpc_call *call, struct sk_buff *skb,
rxrpc_seq_t seq,
struct skcipher_request *req)
{
struct rxkad_level1_hdr sechdr;
struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
struct rxrpc_crypt iv;
struct scatterlist sg[16];
u32 data_size, buf;
u16 check;
int ret;
_enter("");
if (sp->len < 8)
return rxrpc_abort_eproto(call, skb, RXKADSEALEDINCON,
rxkad_abort_1_short_header);
/* Decrypt the skbuff in-place. TODO: We really want to decrypt
* directly into the target buffer.
*/
sg_init_table(sg, ARRAY_SIZE(sg));
ret = skb_to_sgvec(skb, sg, sp->offset, 8);
if (unlikely(ret < 0))
return ret;
/* start the decryption afresh */
memset(&iv, 0, sizeof(iv));
skcipher_request_set_sync_tfm(req, call->conn->rxkad.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, sp->offset, &sechdr, sizeof(sechdr)) < 0)
return rxrpc_abort_eproto(call, skb, RXKADDATALEN,
rxkad_abort_1_short_encdata);
sp->offset += sizeof(sechdr);
sp->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)
return rxrpc_abort_eproto(call, skb, RXKADSEALEDINCON,
rxkad_abort_1_short_check);
if (data_size > sp->len)
return rxrpc_abort_eproto(call, skb, RXKADDATALEN,
rxkad_abort_1_short_data);
sp->len = data_size;
_leave(" = 0 [dlen=%x]", data_size);
return 0;
}
/*
* wholly decrypt a packet (level 2 security)
*/
static int rxkad_verify_packet_2(struct rxrpc_call *call, struct sk_buff *skb,
rxrpc_seq_t seq,
struct skcipher_request *req)
{
const struct rxrpc_key_token *token;
struct rxkad_level2_hdr sechdr;
struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
struct rxrpc_crypt iv;
struct scatterlist _sg[4], *sg;
u32 data_size, buf;
u16 check;
int nsg, ret;
_enter(",{%d}", sp->len);
if (sp->len < 8)
return rxrpc_abort_eproto(call, skb, RXKADSEALEDINCON,
rxkad_abort_2_short_header);
/* Decrypt the skbuff in-place. TODO: We really want to decrypt
* directly into the target buffer.
*/
sg = _sg;
nsg = skb_shinfo(skb)->nr_frags + 1;
if (nsg <= 4) {
nsg = 4;
} else {
sg = kmalloc_array(nsg, sizeof(*sg), GFP_NOIO);
if (!sg)
return -ENOMEM;
}
sg_init_table(sg, nsg);
ret = skb_to_sgvec(skb, sg, sp->offset, sp->len);
if (unlikely(ret < 0)) {
if (sg != _sg)
kfree(sg);
return ret;
}
/* decrypt from the session key */
token = call->conn->key->payload.data[0];
memcpy(&iv, token->kad->session_key, sizeof(iv));
skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher);
skcipher_request_set_callback(req, 0, NULL, NULL);
skcipher_request_set_crypt(req, sg, sg, sp->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, sp->offset, &sechdr, sizeof(sechdr)) < 0)
return rxrpc_abort_eproto(call, skb, RXKADDATALEN,
rxkad_abort_2_short_len);
sp->offset += sizeof(sechdr);
sp->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)
return rxrpc_abort_eproto(call, skb, RXKADSEALEDINCON,
rxkad_abort_2_short_check);
if (data_size > sp->len)
return rxrpc_abort_eproto(call, skb, RXKADDATALEN,
rxkad_abort_2_short_data);
sp->len = data_size;
_leave(" = 0 [dlen=%x]", data_size);
return 0;
}
/*
* Verify the security on a received packet and the subpackets therein.
*/
static int rxkad_verify_packet(struct rxrpc_call *call, struct sk_buff *skb)
{
struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
struct skcipher_request *req;
struct rxrpc_crypt iv;
struct scatterlist sg;
union {
__be32 buf[2];
} crypto __aligned(8);
rxrpc_seq_t seq = sp->hdr.seq;
int ret;
u16 cksum;
u32 x, y;
_enter("{%d{%x}},{#%u}",
call->debug_id, key_serial(call->conn->key), seq);
if (!call->conn->rxkad.cipher)
return 0;
req = rxkad_get_call_crypto(call);
if (!req)
return -ENOMEM;
/* continue encrypting from where we left off */
memcpy(&iv, call->conn->rxkad.csum_iv.x, sizeof(iv));
/* validate the security checksum */
x = (call->cid & RXRPC_CHANNELMASK) << (32 - RXRPC_CIDSHIFT);
x |= seq & 0x3fffffff;
crypto.buf[0] = htonl(call->call_id);
crypto.buf[1] = htonl(x);
sg_init_one(&sg, crypto.buf, 8);
skcipher_request_set_sync_tfm(req, call->conn->rxkad.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(crypto.buf[1]);
cksum = (y >> 16) & 0xffff;
if (cksum == 0)
cksum = 1; /* zero checksums are not permitted */
if (cksum != sp->hdr.cksum) {
ret = rxrpc_abort_eproto(call, skb, RXKADSEALEDINCON,
rxkad_abort_bad_checksum);
goto out;
}
switch (call->conn->security_level) {
case RXRPC_SECURITY_PLAIN:
ret = 0;
break;
case RXRPC_SECURITY_AUTH:
ret = rxkad_verify_packet_1(call, skb, seq, req);
break;
case RXRPC_SECURITY_ENCRYPT:
ret = rxkad_verify_packet_2(call, skb, seq, req);
break;
default:
ret = -ENOANO;
break;
}
out:
skcipher_request_free(req);
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}", conn->debug_id);
get_random_bytes(&conn->rxkad.nonce, sizeof(conn->rxkad.nonce));
challenge.version = htonl(2);
challenge.nonce = htonl(conn->rxkad.nonce);
challenge.min_level = htonl(0);
challenge.__padding = 0;
msg.msg_name = &conn->peer->srx.transport;
msg.msg_namelen = conn->peer->srx.transport_len;
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->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);
ret = kernel_sendmsg(conn->local->socket, &msg, iov, 2, len);
if (ret < 0) {
trace_rxrpc_tx_fail(conn->debug_id, serial, ret,
rxrpc_tx_point_rxkad_challenge);
return -EAGAIN;
}
conn->peer->last_tx_at = ktime_get_seconds();
trace_rxrpc_tx_packet(conn->debug_id, &whdr,
rxrpc_tx_point_rxkad_challenge);
_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->peer->srx.transport;
msg.msg_namelen = conn->peer->srx.transport_len;
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);
ret = kernel_sendmsg(conn->local->socket, &msg, iov, 3, len);
if (ret < 0) {
trace_rxrpc_tx_fail(conn->debug_id, serial, ret,
rxrpc_tx_point_rxkad_response);
return -EAGAIN;
}
conn->peer->last_tx_at = ktime_get_seconds();
_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 int rxkad_encrypt_response(struct rxrpc_connection *conn,
struct rxkad_response *resp,
const struct rxkad_key *s2)
{
struct skcipher_request *req;
struct rxrpc_crypt iv;
struct scatterlist sg[1];
req = skcipher_request_alloc(&conn->rxkad.cipher->base, GFP_NOFS);
if (!req)
return -ENOMEM;
/* 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_sync_tfm(req, conn->rxkad.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_free(req);
return 0;
}
/*
* respond to a challenge packet
*/
static int rxkad_respond_to_challenge(struct rxrpc_connection *conn,
struct sk_buff *skb)
{
const struct rxrpc_key_token *token;
struct rxkad_challenge challenge;
struct rxkad_response *resp;
struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
u32 version, nonce, min_level;
int ret = -EPROTO;
_enter("{%d,%x}", conn->debug_id, key_serial(conn->key));
if (!conn->key)
return rxrpc_abort_conn(conn, skb, RX_PROTOCOL_ERROR, -EPROTO,
rxkad_abort_chall_no_key);
ret = key_validate(conn->key);
if (ret < 0)
return rxrpc_abort_conn(conn, skb, RXKADEXPIRED, ret,
rxkad_abort_chall_key_expired);
if (skb_copy_bits(skb, sizeof(struct rxrpc_wire_header),
&challenge, sizeof(challenge)) < 0)
return rxrpc_abort_conn(conn, skb, RXKADPACKETSHORT, -EPROTO,
rxkad_abort_chall_short);
version = ntohl(challenge.version);
nonce = ntohl(challenge.nonce);
min_level = ntohl(challenge.min_level);
trace_rxrpc_rx_challenge(conn, sp->hdr.serial, version, nonce, min_level);
if (version != RXKAD_VERSION)
return rxrpc_abort_conn(conn, skb, RXKADINCONSISTENCY, -EPROTO,
rxkad_abort_chall_version);
if (conn->security_level < min_level)
return rxrpc_abort_conn(conn, skb, RXKADLEVELFAIL, -EACCES,
rxkad_abort_chall_level);
token = conn->key->payload.data[0];
/* build the response packet */
resp = kzalloc(sizeof(struct rxkad_response), GFP_NOFS);
if (!resp)
return -ENOMEM;
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->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);
ret = rxkad_encrypt_response(conn, resp, token->kad);
if (ret == 0)
ret = rxkad_send_response(conn, &sp->hdr, resp, token->kad);
kfree(resp);
return ret;
}
/*
* decrypt the kerberos IV ticket in the response
*/
static int rxkad_decrypt_ticket(struct rxrpc_connection *conn,
struct key *server_key,
struct sk_buff *skb,
void *ticket, size_t ticket_len,
struct rxrpc_crypt *_session_key,
time64_t *_expiry)
{
struct skcipher_request *req;
struct rxrpc_crypt iv, key;
struct scatterlist sg[1];
struct in_addr addr;
unsigned int life;
time64_t issue, now;
bool little_endian;
u8 *p, *q, *name, *end;
_enter("{%d},{%x}", conn->debug_id, key_serial(server_key));
*_expiry = 0;
ASSERT(server_key->payload.data[0] != NULL);
ASSERTCMP((unsigned long) ticket & 7UL, ==, 0);
memcpy(&iv, &server_key->payload.data[2], sizeof(iv));
req = skcipher_request_alloc(server_key->payload.data[0], GFP_NOFS);
if (!req)
return -ENOMEM;
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(field, fieldl) \
({ \
u8 *__str = p; \
q = memchr(p, 0, end - p); \
if (!q || q - p > field##_SZ) \
return rxrpc_abort_conn( \
conn, skb, RXKADBADTICKET, -EPROTO, \
rxkad_abort_resp_tkt_##fieldl); \
for (; p < q; p++) \
if (!isprint(*p)) \
return rxrpc_abort_conn( \
conn, skb, RXKADBADTICKET, -EPROTO, \
rxkad_abort_resp_tkt_##fieldl); \
p++; \
__str; \
})
/* extract the ticket flags */
_debug("KIV FLAGS: %x", *p);
little_endian = *p & 1;
p++;
/* extract the authentication name */
name = Z(ANAME, aname);
_debug("KIV ANAME: %s", name);
/* extract the principal's instance */
name = Z(INST, inst);
_debug("KIV INST : %s", name);
/* extract the principal's authentication domain */
name = Z(REALM, realm);
_debug("KIV REALM: %s", name);
if (end - p < 4 + 8 + 4 + 2)
return rxrpc_abort_conn(conn, skb, RXKADBADTICKET, -EPROTO,
rxkad_abort_resp_tkt_short);
/* 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 = rxrpc_u32_to_time64(le32_to_cpu(stamp));
} else {
__be32 stamp;
memcpy(&stamp, p, 4);
issue = rxrpc_u32_to_time64(be32_to_cpu(stamp));
}
p += 4;
now = ktime_get_real_seconds();
_debug("KIV ISSUE: %llx [%llx]", issue, now);
/* check the ticket is in date */
if (issue > now)
return rxrpc_abort_conn(conn, skb, RXKADNOAUTH, -EKEYREJECTED,
rxkad_abort_resp_tkt_future);
if (issue < now - life)
return rxrpc_abort_conn(conn, skb, RXKADEXPIRED, -EKEYEXPIRED,
rxkad_abort_resp_tkt_expired);
*_expiry = issue + life;
/* get the service name */
name = Z(SNAME, sname);
_debug("KIV SNAME: %s", name);
/* get the service instance name */
name = Z(INST, sinst);
_debug("KIV SINST: %s", name);
return 0;
}
/*
* decrypt the response packet
*/
static void rxkad_decrypt_response(struct rxrpc_connection *conn,
struct rxkad_response *resp,
const struct rxrpc_crypt *session_key)
{
struct skcipher_request *req = rxkad_ci_req;
struct scatterlist sg[1];
struct rxrpc_crypt iv;
_enter(",,%08x%08x",
ntohl(session_key->n[0]), ntohl(session_key->n[1]));
mutex_lock(&rxkad_ci_mutex);
if (crypto_sync_skcipher_setkey(rxkad_ci, session_key->x,
sizeof(*session_key)) < 0)
BUG();