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mptcp: Add key generation and token tree

Browse source 
Generate the local keys, IDSN, and token when creating a new socket.
Introduce the token tree to track all tokens in use using a radix tree
with the MPTCP token itself as the index.

Override the rebuild_header callback in inet_connection_sock_af_ops for
creating the local key on a new outgoing connection.

Override the init_req callback of tcp_request_sock_ops for creating the
local key on a new incoming connection.

Will be used to obtain the MPTCP parent socket to handle incoming joins.

Co-developed-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Co-developed-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Florian Westphal <fw@strlen.de>
Co-developed-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Peter Krystad <peter.krystad@linux.intel.com>
Signed-off-by: Christoph Paasch <cpaasch@apple.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Peter Krystad 2020-01-21 16:56:20 -08:00 committed by David S. Miller
parent cf7da0d66c
commit 79c0949e9a
6 changed files with 428 additions and 8 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

2
net/mptcp/Makefile
View file

@ -1,4 +1,4 @@
# SPDX-License-Identifier: GPL-2.0
obj-$(CONFIG_MPTCP) += mptcp.o
mptcp-y := protocol.o subflow.o options.o
mptcp-y := protocol.o subflow.o options.o token.o crypto.o

122
net/mptcp/crypto.c Normal file
View file

@ -0,0 +1,122 @@
// SPDX-License-Identifier: GPL-2.0
/* Multipath TCP cryptographic functions
* Copyright (c) 2017 - 2019, Intel Corporation.
*
* Note: This code is based on mptcp_ctrl.c, mptcp_ipv4.c, and
* mptcp_ipv6 from multipath-tcp.org, authored by:
*
* Sébastien Barré <sebastien.barre@uclouvain.be>
* Christoph Paasch <christoph.paasch@uclouvain.be>
* Jaakko Korkeaniemi <jaakko.korkeaniemi@aalto.fi>
* Gregory Detal <gregory.detal@uclouvain.be>
* Fabien Duchêne <fabien.duchene@uclouvain.be>
* Andreas Seelinger <Andreas.Seelinger@rwth-aachen.de>
* Lavkesh Lahngir <lavkesh51@gmail.com>
* Andreas Ripke <ripke@neclab.eu>
* Vlad Dogaru <vlad.dogaru@intel.com>
* Octavian Purdila <octavian.purdila@intel.com>
* John Ronan <jronan@tssg.org>
* Catalin Nicutar <catalin.nicutar@gmail.com>
* Brandon Heller <brandonh@stanford.edu>
*/
#include <linux/kernel.h>
#include <linux/cryptohash.h>
#include <asm/unaligned.h>
#include "protocol.h"
struct sha1_state {
u32 workspace[SHA_WORKSPACE_WORDS];
u32 digest[SHA_DIGEST_WORDS];
unsigned int count;
};
static void sha1_init(struct sha1_state *state)
{
sha_init(state->digest);
state->count = 0;
}
static void sha1_update(struct sha1_state *state, u8 *input)
{
sha_transform(state->digest, input, state->workspace);
state->count += SHA_MESSAGE_BYTES;
}
static void sha1_pad_final(struct sha1_state *state, u8 *input,
unsigned int length, __be32 *mptcp_hashed_key)
{
int i;
input[length] = 0x80;
memset(&input[length + 1], 0, SHA_MESSAGE_BYTES - length - 9);
put_unaligned_be64((length + state->count) << 3,
&input[SHA_MESSAGE_BYTES - 8]);
sha_transform(state->digest, input, state->workspace);
for (i = 0; i < SHA_DIGEST_WORDS; ++i)
put_unaligned_be32(state->digest[i], &mptcp_hashed_key[i]);
memzero_explicit(state->workspace, SHA_WORKSPACE_WORDS << 2);
}
void mptcp_crypto_key_sha(u64 key, u32 *token, u64 *idsn)
{
__be32 mptcp_hashed_key[SHA_DIGEST_WORDS];
u8 input[SHA_MESSAGE_BYTES];
struct sha1_state state;
sha1_init(&state);
put_unaligned_be64(key, input);
sha1_pad_final(&state, input, 8, mptcp_hashed_key);
if (token)
*token = be32_to_cpu(mptcp_hashed_key[0]);
if (idsn)
*idsn = be64_to_cpu(*((__be64 *)&mptcp_hashed_key[3]));
}
void mptcp_crypto_hmac_sha(u64 key1, u64 key2, u32 nonce1, u32 nonce2,
u32 *hash_out)
{
u8 input[SHA_MESSAGE_BYTES * 2];
struct sha1_state state;
u8 key1be[8];
u8 key2be[8];
int i;
put_unaligned_be64(key1, key1be);
put_unaligned_be64(key2, key2be);
/* Generate key xored with ipad */
memset(input, 0x36, SHA_MESSAGE_BYTES);
for (i = 0; i < 8; i++)
input[i] ^= key1be[i];
for (i = 0; i < 8; i++)
input[i + 8] ^= key2be[i];
put_unaligned_be32(nonce1, &input[SHA_MESSAGE_BYTES]);
put_unaligned_be32(nonce2, &input[SHA_MESSAGE_BYTES + 4]);
sha1_init(&state);
sha1_update(&state, input);
/* emit sha256(K1 || msg) on the second input block, so we can
* reuse 'input' for the last hashing
*/
sha1_pad_final(&state, &input[SHA_MESSAGE_BYTES], 8,
(__force __be32 *)&input[SHA_MESSAGE_BYTES]);
/* Prepare second part of hmac */
memset(input, 0x5C, SHA_MESSAGE_BYTES);
for (i = 0; i < 8; i++)
input[i] ^= key1be[i];
for (i = 0; i < 8; i++)
input[i + 8] ^= key2be[i];
sha1_init(&state);
sha1_update(&state, input);
sha1_pad_final(&state, &input[SHA_MESSAGE_BYTES], SHA_DIGEST_WORDS << 2,
(__be32 *)hash_out);
}

16
net/mptcp/protocol.c
View file

@ -201,6 +201,7 @@ static void mptcp_close(struct sock *sk, long timeout)
struct mptcp_subflow_context *subflow, *tmp;
struct mptcp_sock *msk = mptcp_sk(sk);
mptcp_token_destroy(msk->token);
inet_sk_state_store(sk, TCP_CLOSE);
lock_sock(sk);
@ -281,8 +282,10 @@ static struct sock *mptcp_accept(struct sock *sk, int flags, int *err,
msk = mptcp_sk(new_mptcp_sock);
msk->remote_key = subflow->remote_key;
msk->local_key = subflow->local_key;
msk->token = subflow->token;
msk->subflow = NULL;
mptcp_token_update_accept(newsk, new_mptcp_sock);
newsk = new_mptcp_sock;
mptcp_copy_inaddrs(newsk, ssk);
list_add(&subflow->node, &msk->conn_list);
@ -299,6 +302,10 @@ static struct sock *mptcp_accept(struct sock *sk, int flags, int *err,
return newsk;
}
static void mptcp_destroy(struct sock *sk)
{
}
static int mptcp_get_port(struct sock *sk, unsigned short snum)
{
struct mptcp_sock *msk = mptcp_sk(sk);
@ -331,6 +338,7 @@ void mptcp_finish_connect(struct sock *ssk)
*/
WRITE_ONCE(msk->remote_key, subflow->remote_key);
WRITE_ONCE(msk->local_key, subflow->local_key);
WRITE_ONCE(msk->token, subflow->token);
}
static void mptcp_sock_graft(struct sock *sk, struct socket *parent)
@ -349,6 +357,7 @@ static struct proto mptcp_prot = {
.close = mptcp_close,
.accept = mptcp_accept,
.shutdown = tcp_shutdown,
.destroy = mptcp_destroy,
.sendmsg = mptcp_sendmsg,
.recvmsg = mptcp_recvmsg,
.hash = inet_hash,
@ -568,6 +577,12 @@ void __init mptcp_init(void)
static struct proto_ops mptcp_v6_stream_ops;
static struct proto mptcp_v6_prot;
static void mptcp_v6_destroy(struct sock *sk)
{
mptcp_destroy(sk);
inet6_destroy_sock(sk);
}
static struct inet_protosw mptcp_v6_protosw = {
.type = SOCK_STREAM,
.protocol = IPPROTO_MPTCP,
@ -583,6 +598,7 @@ int mptcpv6_init(void)
mptcp_v6_prot = mptcp_prot;
strcpy(mptcp_v6_prot.name, "MPTCPv6");
mptcp_v6_prot.slab = NULL;
mptcp_v6_prot.destroy = mptcp_v6_destroy;
mptcp_v6_prot.obj_size = sizeof(struct mptcp_sock) +
sizeof(struct ipv6_pinfo);

32
net/mptcp/protocol.h
View file

@ -7,6 +7,10 @@
#ifndef __MPTCP_PROTOCOL_H
#define __MPTCP_PROTOCOL_H
#include <linux/random.h>
#include <net/tcp.h>
#include <net/inet_connection_sock.h>
#define MPTCP_SUPPORTED_VERSION 0
/* MPTCP option bits */
@ -42,6 +46,7 @@ struct mptcp_sock {
struct inet_connection_sock sk;
u64 local_key;
u64 remote_key;
u32 token;
struct list_head conn_list;
struct socket *subflow; /* outgoing connect/listener/!mp_capable */
};
@ -61,6 +66,8 @@ struct mptcp_subflow_request_sock {
backup : 1;
u64 local_key;
u64 remote_key;
u64 idsn;
u32 token;
};
static inline struct mptcp_subflow_request_sock *
@ -74,6 +81,8 @@ struct mptcp_subflow_context {
struct list_head node;/* conn_list of subflows */
u64 local_key;
u64 remote_key;
u64 idsn;
u32 token;
u32 request_mptcp : 1, /* send MP_CAPABLE */
mp_capable : 1, /* remote is MPTCP capable */
fourth_ack : 1, /* send initial DSS */
@ -112,4 +121,27 @@ void mptcp_get_options(const struct sk_buff *skb,
void mptcp_finish_connect(struct sock *sk);
int mptcp_token_new_request(struct request_sock *req);
void mptcp_token_destroy_request(u32 token);
int mptcp_token_new_connect(struct sock *sk);
int mptcp_token_new_accept(u32 token);
void mptcp_token_update_accept(struct sock *sk, struct sock *conn);
void mptcp_token_destroy(u32 token);
void mptcp_crypto_key_sha(u64 key, u32 *token, u64 *idsn);
static inline void mptcp_crypto_key_gen_sha(u64 *key, u32 *token, u64 *idsn)
{
/* we might consider a faster version that computes the key as a
* hash of some information available in the MPTCP socket. Use
* random data at the moment, as it's probably the safest option
* in case multiple sockets are opened in different namespaces at
* the same time.
*/
get_random_bytes(key, sizeof(u64));
mptcp_crypto_key_sha(*key, token, idsn);
}
void mptcp_crypto_hmac_sha(u64 key1, u64 key2, u32 nonce1, u32 nonce2,
u32 *hash_out);
#endif /* __MPTCP_PROTOCOL_H */

69
net/mptcp/subflow.c
View file

@ -4,6 +4,8 @@
* Copyright (c) 2017 - 2019, Intel Corporation.
*/
#define pr_fmt(fmt) "MPTCP: " fmt
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/netdevice.h>
@ -18,6 +20,33 @@
#include <net/mptcp.h>
#include "protocol.h"
static int subflow_rebuild_header(struct sock *sk)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
int err = 0;
if (subflow->request_mptcp && !subflow->token) {
pr_debug("subflow=%p", sk);
err = mptcp_token_new_connect(sk);
}
if (err)
return err;
return subflow->icsk_af_ops->rebuild_header(sk);
}
static void subflow_req_destructor(struct request_sock *req)
{
struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
pr_debug("subflow_req=%p", subflow_req);
if (subflow_req->mp_capable)
mptcp_token_destroy_request(subflow_req->token);
tcp_request_sock_ops.destructor(req);
}
static void subflow_init_req(struct request_sock *req,
const struct sock *sk_listener,
struct sk_buff *skb)
@ -42,7 +71,12 @@ static void subflow_init_req(struct request_sock *req,
#endif
if (rx_opt.mptcp.mp_capable && listener->request_mptcp) {
subflow_req->mp_capable = 1;
int err;
err = mptcp_token_new_request(req);
if (err == 0)
subflow_req->mp_capable = 1;
subflow_req->remote_key = rx_opt.mptcp.sndr_key;
}
}
@ -150,16 +184,28 @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk,
req_unhash, own_req);
if (child && *own_req) {
if (!mptcp_subflow_ctx(child)) {
pr_debug("Closing child socket");
inet_sk_set_state(child, TCP_CLOSE);
sock_set_flag(child, SOCK_DEAD);
inet_csk_destroy_sock(child);
child = NULL;
struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(child);
/* we have null ctx on TCP fallback, not fatal on MPC
* handshake
*/
if (!ctx)
return child;
if (ctx->mp_capable) {
if (mptcp_token_new_accept(ctx->token))
goto close_child;
}
}
return child;
close_child:
pr_debug("closing child socket");
tcp_send_active_reset(child, GFP_ATOMIC);
inet_csk_prepare_forced_close(child);
tcp_done(child);
return NULL;
}
static struct inet_connection_sock_af_ops subflow_specific;
@ -224,6 +270,7 @@ int mptcp_subflow_create_socket(struct sock *sk, struct socket **new_sock)
pr_debug("subflow=%p", subflow);
*new_sock = sf;
sock_hold(sk);
subflow->conn = sk;
return 0;
@ -286,6 +333,9 @@ static void subflow_ulp_release(struct sock *sk)
if (!ctx)
return;
if (ctx->conn)
sock_put(ctx->conn);
kfree_rcu(ctx, rcu);
}
@ -323,6 +373,7 @@ static void subflow_ulp_clone(const struct request_sock *req,
new_ctx->fourth_ack = 1;
new_ctx->remote_key = subflow_req->remote_key;
new_ctx->local_key = subflow_req->local_key;
new_ctx->token = subflow_req->token;
}
static struct tcp_ulp_ops subflow_ulp_ops __read_mostly = {
@ -346,6 +397,8 @@ static int subflow_ops_init(struct request_sock_ops *subflow_ops)
if (!subflow_ops->slab)
return -ENOMEM;
subflow_ops->destructor = subflow_req_destructor;
return 0;
}
@ -362,6 +415,7 @@ void mptcp_subflow_init(void)
subflow_specific.conn_request = subflow_v4_conn_request;
subflow_specific.syn_recv_sock = subflow_syn_recv_sock;
subflow_specific.sk_rx_dst_set = subflow_finish_connect;
subflow_specific.rebuild_header = subflow_rebuild_header;
#if IS_ENABLED(CONFIG_MPTCP_IPV6)
subflow_request_sock_ipv6_ops = tcp_request_sock_ipv6_ops;
@ -371,6 +425,7 @@ void mptcp_subflow_init(void)
subflow_v6_specific.conn_request = subflow_v6_conn_request;
subflow_v6_specific.syn_recv_sock = subflow_syn_recv_sock;
subflow_v6_specific.sk_rx_dst_set = subflow_finish_connect;
subflow_v6_specific.rebuild_header = subflow_rebuild_header;
subflow_v6m_specific = subflow_v6_specific;
subflow_v6m_specific.queue_xmit = ipv4_specific.queue_xmit;

195
net/mptcp/token.c Normal file
View file

@ -0,0 +1,195 @@
// SPDX-License-Identifier: GPL-2.0
/* Multipath TCP token management
* Copyright (c) 2017 - 2019, Intel Corporation.
*
* Note: This code is based on mptcp_ctrl.c from multipath-tcp.org,
* authored by:
*
* Sébastien Barré <sebastien.barre@uclouvain.be>
* Christoph Paasch <christoph.paasch@uclouvain.be>
* Jaakko Korkeaniemi <jaakko.korkeaniemi@aalto.fi>
* Gregory Detal <gregory.detal@uclouvain.be>
* Fabien Duchêne <fabien.duchene@uclouvain.be>
* Andreas Seelinger <Andreas.Seelinger@rwth-aachen.de>
* Lavkesh Lahngir <lavkesh51@gmail.com>
* Andreas Ripke <ripke@neclab.eu>
* Vlad Dogaru <vlad.dogaru@intel.com>
* Octavian Purdila <octavian.purdila@intel.com>
* John Ronan <jronan@tssg.org>
* Catalin Nicutar <catalin.nicutar@gmail.com>
* Brandon Heller <brandonh@stanford.edu>
*/
#define pr_fmt(fmt) "MPTCP: " fmt
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/radix-tree.h>
#include <linux/ip.h>
#include <linux/tcp.h>
#include <net/sock.h>
#include <net/inet_common.h>
#include <net/protocol.h>
#include <net/mptcp.h>
#include "protocol.h"
static RADIX_TREE(token_tree, GFP_ATOMIC);
static RADIX_TREE(token_req_tree, GFP_ATOMIC);
static DEFINE_SPINLOCK(token_tree_lock);
static int token_used __read_mostly;
/**
* mptcp_token_new_request - create new key/idsn/token for subflow_request
* @req - the request socket
*
* This function is called when a new mptcp connection is coming in.
*
* It creates a unique token to identify the new mptcp connection,
* a secret local key and the initial data sequence number (idsn).
*
* Returns 0 on success.
*/
int mptcp_token_new_request(struct request_sock *req)
{
struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
int err;
while (1) {
u32 token;
mptcp_crypto_key_gen_sha(&subflow_req->local_key,
&subflow_req->token,
&subflow_req->idsn);
pr_debug("req=%p local_key=%llu, token=%u, idsn=%llu\n",
req, subflow_req->local_key, subflow_req->token,
subflow_req->idsn);
token = subflow_req->token;
spin_lock_bh(&token_tree_lock);
if (!radix_tree_lookup(&token_req_tree, token) &&
!radix_tree_lookup(&token_tree, token))
break;
spin_unlock_bh(&token_tree_lock);
}
err = radix_tree_insert(&token_req_tree,
subflow_req->token, &token_used);
spin_unlock_bh(&token_tree_lock);
return err;
}
/**
* mptcp_token_new_connect - create new key/idsn/token for subflow
* @sk - the socket that will initiate a connection
*
* This function is called when a new outgoing mptcp connection is
* initiated.
*
* It creates a unique token to identify the new mptcp connection,
* a secret local key and the initial data sequence number (idsn).
*
* On success, the mptcp connection can be found again using
* the computed token at a later time, this is needed to process
* join requests.
*
* returns 0 on success.
*/
int mptcp_token_new_connect(struct sock *sk)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
struct sock *mptcp_sock = subflow->conn;
int err;
while (1) {
u32 token;
mptcp_crypto_key_gen_sha(&subflow->local_key, &subflow->token,
&subflow->idsn);
pr_debug("ssk=%p, local_key=%llu, token=%u, idsn=%llu\n",
sk, subflow->local_key, subflow->token, subflow->idsn);
token = subflow->token;
spin_lock_bh(&token_tree_lock);
if (!radix_tree_lookup(&token_req_tree, token) &&
!radix_tree_lookup(&token_tree, token))
break;
spin_unlock_bh(&token_tree_lock);
}
err = radix_tree_insert(&token_tree, subflow->token, mptcp_sock);
spin_unlock_bh(&token_tree_lock);
return err;
}
/**
* mptcp_token_new_accept - insert token for later processing
* @token: the token to insert to the tree
*
* Called when a SYN packet creates a new logical connection, i.e.
* is not a join request.
*
* We don't have an mptcp socket yet at that point.
* This is paired with mptcp_token_update_accept, called on accept().
*/
int mptcp_token_new_accept(u32 token)
{
int err;
spin_lock_bh(&token_tree_lock);
err = radix_tree_insert(&token_tree, token, &token_used);
spin_unlock_bh(&token_tree_lock);
return err;
}
/**
* mptcp_token_update_accept - update token to map to mptcp socket
* @conn: the new struct mptcp_sock
* @sk: the initial subflow for this mptcp socket
*
* Called when the first mptcp socket is created on accept to
* refresh the dummy mapping (done to reserve the token) with
* the mptcp_socket structure that wasn't allocated before.
*/
void mptcp_token_update_accept(struct sock *sk, struct sock *conn)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
void __rcu **slot;
spin_lock_bh(&token_tree_lock);
slot = radix_tree_lookup_slot(&token_tree, subflow->token);
WARN_ON_ONCE(!slot);
if (slot) {
WARN_ON_ONCE(rcu_access_pointer(*slot) != &token_used);
radix_tree_replace_slot(&token_tree, slot, conn);
}
spin_unlock_bh(&token_tree_lock);
}
/**
* mptcp_token_destroy_request - remove mptcp connection/token
* @token - token of mptcp connection to remove
*
* Remove not-yet-fully-established incoming connection identified
* by @token.
*/
void mptcp_token_destroy_request(u32 token)
{
spin_lock_bh(&token_tree_lock);
radix_tree_delete(&token_req_tree, token);
spin_unlock_bh(&token_tree_lock);
}
/**
* mptcp_token_destroy - remove mptcp connection/token
* @token - token of mptcp connection to remove
*
* Remove the connection identified by @token.
*/
void mptcp_token_destroy(u32 token)
{
spin_lock_bh(&token_tree_lock);
radix_tree_delete(&token_tree, token);
spin_unlock_bh(&token_tree_lock);
}