[RFC] tcp: Initial support for RFC5925 auth option

Leonard Crestez
2021-07-19T11:25:09Z

This is similar to TCP MD5 in functionality but it's sufficiently
different that userspace interface and wire formats are incompatible.
Compared to TCP-MD5 more algorithms are supported and multiple keys can
be used on the same connection but there is still no negotiation
mechanism.

Expected use-case is protecting long-duration BGP/LDP connections
between routers using pre-shared keys.

This is an early version which focuses on getting the correct
signature bits on the wire in a way that can interoperate with other
implementations. Major issues still need to be solved:

* Lockdep warnings (incorrect context for initializing shash)
* Support for aes-128-cmac-96
* Binding keys to addresses and/or interfaces similar to md5
* Sequence Number Extension

A small test suite is here: https://github.com/cdleonard/tcp-authopt-test
The tests work by establishing loopback TCP connections, capturing
packets with scapy and validating signatures.

Changes for yabgp are here:
https://github.com/cdleonard/yabgp/commits/tcp_authopt
The patched version of yabgp can establish a BGP session protected by
TCP Authentication Option with a Cisco IOS-XR router.

I'm especially interested in feedback regarding ABI and testing.

Signed-off-by: Leonard Crestez <cdleonard@gmail.com>

---

Allocating shash requires user context but holding a struct tfm in
tcp_authopt_key_info allocated by tcp_set_authopt_key doesn't work
because when a server handshake is succesful the server socket needs to
copy the keys of the listen socket in softirq context.

Sharing the crypto_shash tfm between listen and server sockets doesn't
work well either because keys for each connection (and each syn packet)
are different and the hmac or cmac key is per-tfm rather than per
shash_desc. The server sockets would need locking to access their shared
tfm.

Simplest solution would be to allocate one shash for each CPU and borrow
it for each hashing operation. TCP-MD5 allocates one ahash globally but
that can't work for hmac/cmac because of setkey.

Signed-off-by: Leonard Crestez <cdleonard@gmail.com>
---
include/linux/tcp.h | 6 +
include/net/tcp.h | 1 +
include/net/tcp_authopt.h | 103 ++++++
include/uapi/linux/snmp.h | 1 +
include/uapi/linux/tcp.h | 40 +++
net/ipv4/Kconfig | 14 +
net/ipv4/Makefile | 1 +
net/ipv4/proc.c | 1 +
net/ipv4/tcp.c | 7 +
net/ipv4/tcp_authopt.c | 718 ++++++++++++++++++++++++++++++++++++++
net/ipv4/tcp_input.c | 17 +
net/ipv4/tcp_ipv4.c | 5 +
net/ipv4/tcp_minisocks.c | 2 +
net/ipv4/tcp_output.c | 65 +++-
14 files changed, 980 insertions(+), 1 deletion(-)
create mode 100644 include/net/tcp_authopt.h
create mode 100644 net/ipv4/tcp_authopt.c

diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 48d8a363319e..cfddfc720b00 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -140,10 +140,12 @@ struct tcp_request_sock {
static inline struct tcp_request_sock *tcp_rsk(const struct request_sock *req)
{
return (struct tcp_request_sock *)req;
}

+struct tcp_authopt_info;
+
struct tcp_sock {
/* inet_connection_sock has to be the first member of tcp_sock */
struct inet_connection_sock inet_conn;
u16 tcp_header_len; /* Bytes of tcp header to send */
u16 gso_segs; /* Max number of segs per GSO packet */
@@ -403,10 +405,14 @@ struct tcp_sock {

/* TCP MD5 Signature Option information */
struct tcp_md5sig_info __rcu *md5sig_info;
#endif

+#ifdef CONFIG_TCP_AUTHOPT
+ struct tcp_authopt_info __rcu *authopt_info;
+#endif
+
/* TCP fastopen related information */
struct tcp_fastopen_request *fastopen_req;
/* fastopen_rsk points to request_sock that resulted in this big
* socket. Used to retransmit SYNACKs etc.
*/
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 17df9b047ee4..767611fd5ec3 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -182,10 +182,11 @@ void tcp_time_wait(struct sock *sk, int state, int timeo);
#define TCPOPT_WINDOW 3 /* Window scaling */
#define TCPOPT_SACK_PERM 4 /* SACK Permitted */
#define TCPOPT_SACK 5 /* SACK Block */
#define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
#define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */
+#define TCPOPT_AUTHOPT 29 /* Auth Option (RFC5925) */
#define TCPOPT_MPTCP 30 /* Multipath TCP (RFC6824) */
#define TCPOPT_FASTOPEN 34 /* Fast open (RFC7413) */
#define TCPOPT_EXP 254 /* Experimental */
/* Magic number to be after the option value for sharing TCP
* experimental options. See draft-ietf-tcpm-experimental-options-00.txt
diff --git a/include/net/tcp_authopt.h b/include/net/tcp_authopt.h
new file mode 100644
index 000000000000..aaab5c955984
--- /dev/null
+++ b/include/net/tcp_authopt.h
@@ -0,0 +1,103 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef _LINUX_TCP_AUTHOPT_H
+#define _LINUX_TCP_AUTHOPT_H
+
+#include <uapi/linux/tcp.h>
+
+/* Representation of a Master Key Tuple as per RFC5925 */
+struct tcp_authopt_key_info {
+ struct hlist_node node;
+ /* Local identifier */
+ u32 local_id;
+ u32 flags;
+ /* Wire identifiers */
+ u8 send_id, recv_id;
+ u8 alg;
+ u8 keylen;
+ u8 key[TCP_AUTHOPT_MAXKEYLEN];
+ u8 maclen;
+ u8 traffic_key_len;
+ struct rcu_head rcu;
+};
+
+/* Per-socket information regarding tcp_authopt */
+struct tcp_authopt_info {
+ struct hlist_head head;
+ u32 local_send_id;
+ u32 src_isn;
+ u32 dst_isn;
+ u8 rnextkeyid;
+ struct rcu_head rcu;
+};
+
+#ifdef CONFIG_TCP_AUTHOPT
+struct tcp_authopt_key_info *tcp_authopt_key_info_lookup(struct sock *sk, int key_id);
+void tcp_authopt_clear(struct sock *sk);
+int tcp_set_authopt(struct sock *sk, sockptr_t optval, unsigned int optlen);
+int tcp_set_authopt_key(struct sock *sk, sockptr_t optval, unsigned int optlen);
+int tcp_authopt_hash(
+ char *hash_location,
+ struct tcp_authopt_key_info *key,
+ struct sock *sk, struct sk_buff *skb);
+int __tcp_authopt_openreq(struct sock *newsk, const struct sock *oldsk, struct request_sock *req);
+static inline int tcp_authopt_openreq(
+ struct sock *newsk,
+ const struct sock *oldsk,
+ struct request_sock *req)
+{
+ if (!rcu_dereference(tcp_sk(oldsk)->authopt_info))
+ return 0;
+ else
+ return __tcp_authopt_openreq(newsk, oldsk, req);
+}
+int __tcp_authopt_inbound_check(
+ struct sock *sk,
+ struct sk_buff *skb,
+ struct tcp_authopt_info *info);
+static inline int tcp_authopt_inbound_check(struct sock *sk, struct sk_buff *skb)
+{
+ struct tcp_authopt_info *info = rcu_dereference(tcp_sk(sk)->authopt_info);
+
+ if (info)
+ return __tcp_authopt_inbound_check(sk, skb, info);
+ else
+ return 0;
+}
+#else
+static inline struct tcp_authopt_key_info *tcp_authopt_key_info_lookup(
+ struct sock *sk,
+ int key_id)
+{
+ return NULL;
+}
+static inline int tcp_set_authopt(struct sock *sk, sockptr_t optval, unsigned int optlen)
+{
+ return -ENOPROTOOPT;
+}
+static inline void tcp_authopt_clear(struct sock *sk)
+{
+}
+static inline int tcp_set_authopt_key(struct sock *sk, sockptr_t optval, unsigned int optlen)
+{
+ return -ENOPROTOOPT;
+}
+static inline int tcp_authopt_hash(
+ char *hash_location,
+ struct tcp_authopt_key_info *key,
+ struct sock *sk, struct sk_buff *skb)
+{
+ return -EINVAL;
+}
+static inline int tcp_authopt_openreq(struct sock *newsk,
+ const struct sock *oldsk,
+ struct request_sock *req)
+{
+ return 0;
+}
+static inline int tcp_authopt_inbound_check(struct sock *sk, struct sk_buff *skb)
+{
+ return 0;
+}
+#endif
+
+#endif /* _LINUX_TCP_AUTHOPT_H */
diff --git a/include/uapi/linux/snmp.h b/include/uapi/linux/snmp.h
index 904909d020e2..1d96030889a1 100644
--- a/include/uapi/linux/snmp.h
+++ b/include/uapi/linux/snmp.h
@@ -290,10 +290,11 @@ enum
LINUX_MIB_TCPDUPLICATEDATAREHASH, /* TCPDuplicateDataRehash */
LINUX_MIB_TCPDSACKRECVSEGS, /* TCPDSACKRecvSegs */
LINUX_MIB_TCPDSACKIGNOREDDUBIOUS, /* TCPDSACKIgnoredDubious */
LINUX_MIB_TCPMIGRATEREQSUCCESS, /* TCPMigrateReqSuccess */
LINUX_MIB_TCPMIGRATEREQFAILURE, /* TCPMigrateReqFailure */
+ LINUX_MIB_TCPAUTHOPTFAILURE, /* TCPAuthOptFailure */
__LINUX_MIB_MAX
};

/* linux Xfrm mib definitions */
enum
diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h
index 8fc09e8638b3..30b8ad769871 100644
--- a/include/uapi/linux/tcp.h
+++ b/include/uapi/linux/tcp.h
@@ -126,10 +126,12 @@ enum {
#define TCP_INQ 36 /* Notify bytes available to read as a cmsg on read */

#define TCP_CM_INQ TCP_INQ

#define TCP_TX_DELAY 37 /* delay outgoing packets by XX usec */
+#define TCP_AUTHOPT 38 /* TCP Authentication Option (RFC2385) */
+#define TCP_AUTHOPT_KEY 39 /* TCP Authentication Option update key (RFC2385) */

#define TCP_REPAIR_ON 1
#define TCP_REPAIR_OFF 0
#define TCP_REPAIR_OFF_NO_WP -1 /* Turn off without window probes */
@@ -340,10 +342,48 @@ struct tcp_diag_md5sig {
__u16 tcpm_keylen;
__be32 tcpm_addr[4];
__u8 tcpm_key[TCP_MD5SIG_MAXKEYLEN];
};

+/* for TCP_AUTHOPT socket option */
+#define TCP_AUTHOPT_MAXKEYLEN 80
+
+#define TCP_AUTHOPT_ALG_HMAC_SHA_1_96 1
+#define TCP_AUTHOPT_ALG_AES_128_CMAC_96 2
+
+/* Per-socket options */
+struct tcp_authopt {
+ /* No flags currently defined */
+ __u32 flags;
+ /* local_id of preferred output key */
+ __u32 local_send_id;
+};
+
+/* Delete the key by local_id and ignore all fields */
+#define TCP_AUTHOPT_KEY_DEL (1 << 0)
+/* Exclude TCP options from signature */
+#define TCP_AUTHOPT_KEY_EXCLUDE_OPTS (1 << 1)
+
+/* Per-key options
+ * Each key is identified by a non-zero local_id which is managed by the application.
+ */
+struct tcp_authopt_key {
+ /* Mix of TCP_AUTHOPT_KEY_ flags */
+ __u32 flags;
+ /* Local identifier */
+ __u32 local_id;
+ /* SendID on the network */
+ __u8 send_id;
+ /* RecvID on the network */
+ __u8 recv_id;
+ /* One of the TCP_AUTHOPT_ALG_* constant */
+ __u8 alg;
+ /* Length of the key buffer */
+ __u8 keylen;
+ __u8 key[TCP_AUTHOPT_MAXKEYLEN];
+};
+
/* setsockopt(fd, IPPROTO_TCP, TCP_ZEROCOPY_RECEIVE, ...) */

#define TCP_RECEIVE_ZEROCOPY_FLAG_TLB_CLEAN_HINT 0x1
struct tcp_zerocopy_receive {
__u64 address; /* in: address of mapping */
diff --git a/net/ipv4/Kconfig b/net/ipv4/Kconfig
index 87983e70f03f..6459f4ea6f1d 100644
--- a/net/ipv4/Kconfig
+++ b/net/ipv4/Kconfig
@@ -740,5 +740,19 @@ config TCP_MD5SIG
RFC2385 specifies a method of giving MD5 protection to TCP sessions.
Its main (only?) use is to protect BGP sessions between core routers
on the Internet.

If unsure, say N.
+
+config TCP_AUTHOPT
+ bool "TCP: Authentication Option support (RFC5925)"
+ select CRYPTO
+ select CRYPTO_SHA1
+ select CRYPTO_HMAC
+ select CRYPTO_AES
+ select CRYPTO_CMAC
+ help
+ RFC5925 specifies a new method of giving protection to TCP sessions.
+ Its intended use is to protect BGP sessions between core routers
+ on the Internet. It obsoletes TCP MD5 (RFC2385) but is incompatible.
+
+ If unsure, say N.
diff --git a/net/ipv4/Makefile b/net/ipv4/Makefile
index bbdd9c44f14e..d336f32ce177 100644
--- a/net/ipv4/Makefile
+++ b/net/ipv4/Makefile
@@ -59,10 +59,11 @@ obj-$(CONFIG_TCP_CONG_NV) += tcp_nv.o
obj-$(CONFIG_TCP_CONG_VENO) += tcp_veno.o
obj-$(CONFIG_TCP_CONG_SCALABLE) += tcp_scalable.o
obj-$(CONFIG_TCP_CONG_LP) += tcp_lp.o
obj-$(CONFIG_TCP_CONG_YEAH) += tcp_yeah.o
obj-$(CONFIG_TCP_CONG_ILLINOIS) += tcp_illinois.o
+obj-$(CONFIG_TCP_AUTHOPT) += tcp_authopt.o
obj-$(CONFIG_NET_SOCK_MSG) += tcp_bpf.o
obj-$(CONFIG_BPF_SYSCALL) += udp_bpf.o
obj-$(CONFIG_NETLABEL) += cipso_ipv4.o

obj-$(CONFIG_XFRM) += xfrm4_policy.o xfrm4_state.o xfrm4_input.o \
diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c
index b0d3a09dc84e..61dd06f8389c 100644
--- a/net/ipv4/proc.c
+++ b/net/ipv4/proc.c
@@ -295,10 +295,11 @@ static const struct snmp_mib snmp4_net_list[] = {
SNMP_MIB_ITEM("TcpDuplicateDataRehash", LINUX_MIB_TCPDUPLICATEDATAREHASH),
SNMP_MIB_ITEM("TCPDSACKRecvSegs", LINUX_MIB_TCPDSACKRECVSEGS),
SNMP_MIB_ITEM("TCPDSACKIgnoredDubious", LINUX_MIB_TCPDSACKIGNOREDDUBIOUS),
SNMP_MIB_ITEM("TCPMigrateReqSuccess", LINUX_MIB_TCPMIGRATEREQSUCCESS),
SNMP_MIB_ITEM("TCPMigrateReqFailure", LINUX_MIB_TCPMIGRATEREQFAILURE),
+ SNMP_MIB_ITEM("TCPAuthOptFailure", LINUX_MIB_TCPAUTHOPTFAILURE),
SNMP_MIB_SENTINEL
};

static void icmpmsg_put_line(struct seq_file *seq, unsigned long *vals,
unsigned short *type, int count)
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 8cb44040ec68..3c29bb579d27 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -271,10 +271,11 @@

#include <net/icmp.h>
#include <net/inet_common.h>
#include <net/tcp.h>
#include <net/mptcp.h>
+#include <net/tcp_authopt.h>
#include <net/xfrm.h>
#include <net/ip.h>
#include <net/sock.h>

#include <linux/uaccess.h>
@@ -3573,10 +3574,16 @@ static int do_tcp_setsockopt(struct sock *sk, int level, int optname,
case TCP_MD5SIG:
case TCP_MD5SIG_EXT:
err = tp->af_specific->md5_parse(sk, optname, optval, optlen);
break;
#endif
+ case TCP_AUTHOPT:
+ err = tcp_set_authopt(sk, optval, optlen);
+ break;
+ case TCP_AUTHOPT_KEY:
+ err = tcp_set_authopt_key(sk, optval, optlen);
+ break;
case TCP_USER_TIMEOUT:
/* Cap the max time in ms TCP will retry or probe the window
* before giving up and aborting (ETIMEDOUT) a connection.
*/
if (val < 0)
diff --git a/net/ipv4/tcp_authopt.c b/net/ipv4/tcp_authopt.c
new file mode 100644
index 000000000000..40ee83fc0afe
--- /dev/null
+++ b/net/ipv4/tcp_authopt.c
@@ -0,0 +1,718 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <linux/kernel.h>
+#include <net/tcp.h>
+#include <net/tcp_authopt.h>
+#include <crypto/hash.h>
+#include <trace/events/tcp.h>
+
+/* All current algorithms have a mac length of 12 but crypto API digestsize can be larger */
+#define TCP_AUTHOPT_MAXMACBUF 20
+#define TCP_AUTHOPT_MAX_TRAFFIC_KEY_LEN 20
+
+struct tcp_authopt_key_info *__tcp_authopt_key_info_lookup(struct sock *sk,
+ struct tcp_authopt_info *info,
+ int key_id)
+{
+ struct tcp_authopt_key_info *key;
+
+ hlist_for_each_entry_rcu(key, &info->head, node, lockdep_sock_is_held(sk))
+ if (key->local_id == key_id)
+ return key;
+
+ return NULL;
+}
+
+struct tcp_authopt_key_info *tcp_authopt_key_info_lookup(struct sock *sk, int key_id)
+{
+ struct tcp_authopt_info *info;
+ struct tcp_authopt_key_info *key;
+
+ info = rcu_dereference_check(tcp_sk(sk)->authopt_info, lockdep_sock_is_held(sk));
+ if (!info)
+ return NULL;
+
+ hlist_for_each_entry_rcu(key, &info->head, node, lockdep_sock_is_held(sk))
+ if (key->local_id == key_id)
+ return key;
+
+ return NULL;
+}
+
+int tcp_set_authopt(struct sock *sk, sockptr_t optval, unsigned int optlen)
+{
+ struct tcp_sock *tp = tcp_sk(sk);
+ struct tcp_authopt opt;
+ struct tcp_authopt_info *info;
+
+ if (optlen < sizeof(opt))
+ return -EINVAL;
+
+ WARN_ON(!lockdep_sock_is_held(sk));
+ if (copy_from_sockptr(&opt, optval, sizeof(opt)))
+ return -EFAULT;
+
+ info = rcu_dereference_check(tp->authopt_info, lockdep_sock_is_held(sk));
+ if (!info) {
+ info = kmalloc(sizeof(*info), GFP_KERNEL | __GFP_ZERO);
+ if (!info)
+ return -ENOMEM;
+
+ sk_nocaps_add(sk, NETIF_F_GSO_MASK);
+ INIT_HLIST_HEAD(&info->head);
+ rcu_assign_pointer(tp->authopt_info, info);
+ }
+ info->local_send_id = opt.local_send_id;
+
+ return 0;
+}
+
+static void tcp_authopt_key_del(struct sock *sk, struct tcp_authopt_key_info *key)
+{
+ hlist_del_rcu(&key->node);
+ atomic_sub(sizeof(*key), &sk->sk_omem_alloc);
+ kfree_rcu(key, rcu);
+}
+
+/* free info and keys but don't touch tp->authopt_info */
+void __tcp_authopt_info_free(struct sock *sk, struct tcp_authopt_info *info)
+{
+ struct hlist_node *n;
+ struct tcp_authopt_key_info *key;
+
+ hlist_for_each_entry_safe(key, n, &info->head, node)
+ tcp_authopt_key_del(sk, key);
+ kfree_rcu(info, rcu);
+}
+
+/* free everything and clear tcp_sock.authopt_info to NULL */
+void tcp_authopt_clear(struct sock *sk)
+{
+ struct tcp_authopt_info *info;
+
+ info = rcu_dereference_protected(tcp_sk(sk)->authopt_info, lockdep_sock_is_held(sk));
+ if (info) {
+ __tcp_authopt_info_free(sk, info);
+ tcp_sk(sk)->authopt_info = NULL;
+ }
+}
+
+int tcp_set_authopt_key(struct sock *sk, sockptr_t optval, unsigned int optlen)
+{
+ struct tcp_authopt_key opt;
+ struct tcp_authopt_info *info;
+ struct tcp_authopt_key_info *key_info;
+ u8 traffic_key_len, maclen;
+
+ if (optlen < sizeof(opt))
+ return -EINVAL;
+
+ if (copy_from_sockptr(&opt, optval, sizeof(opt)))
+ return -EFAULT;
+
+ if (opt.keylen > TCP_AUTHOPT_MAXKEYLEN)
+ return -EINVAL;
+
+ if (opt.local_id == 0)
+ return -EINVAL;
+
+ /* must set authopt before setting keys */
+ info = rcu_dereference_protected(tcp_sk(sk)->authopt_info, lockdep_sock_is_held(sk));
+ if (!info)
+ return -EINVAL;
+
+ if (opt.flags & TCP_AUTHOPT_KEY_DEL) {
+ key_info = __tcp_authopt_key_info_lookup(sk, info, opt.local_id);
+ if (!key_info)
+ return -ENOENT;
+ tcp_authopt_key_del(sk, key_info);
+ return 0;
+ }
+
+ /* check the algorithm */
+ if (opt.alg == TCP_AUTHOPT_ALG_HMAC_SHA_1_96) {
+ traffic_key_len = 20;
+ maclen = 12;
+ } else if (opt.alg == TCP_AUTHOPT_ALG_AES_128_CMAC_96) {
+ traffic_key_len = 16;
+ maclen = 12;
+ } else {
+ return -EINVAL;
+ }
+
+ /* If an old value exists for same local_id it is deleted */
+ key_info = __tcp_authopt_key_info_lookup(sk, info, opt.local_id);
+ if (key_info)
+ tcp_authopt_key_del(sk, key_info);
+ key_info = sock_kmalloc(sk, sizeof(*key_info), GFP_KERNEL | __GFP_ZERO);
+ if (!key_info)
+ return -ENOMEM;
+ key_info->local_id = opt.local_id;
+ key_info->flags = opt.flags & TCP_AUTHOPT_KEY_EXCLUDE_OPTS;
+ key_info->send_id = opt.send_id;
+ key_info->recv_id = opt.recv_id;
+ key_info->alg = opt.alg;
+ key_info->keylen = opt.keylen;
+ memcpy(key_info->key, opt.key, opt.keylen);
+ key_info->maclen = maclen;
+ key_info->traffic_key_len = traffic_key_len;
+ hlist_add_head_rcu(&key_info->node, &info->head);
+
+ return 0;
+}
+
+static int tcp_authopt_clone_keys(struct sock *newsk,
+ const struct sock *oldsk,
+ struct tcp_authopt_info *new_info,
+ struct tcp_authopt_info *old_info)
+{
+ struct tcp_authopt_key_info *old_key;
+ struct tcp_authopt_key_info *new_key;
+
+ hlist_for_each_entry_rcu(old_key, &old_info->head, node, lockdep_sock_is_held(sk)) {
+ new_key = sock_kmalloc(newsk, sizeof(*new_key), GFP_KERNEL);
+ if (!new_key)
+ return -ENOMEM;
+ memcpy(new_key, old_key, sizeof(*new_key));
+ hlist_add_head_rcu(&new_key->node, &new_info->head);
+ }
+
+ return 0;
+}
+
+/** Called to create accepted sockets.
+ *
+ * Need to copy authopt info from listen socket.
+ */
+int __tcp_authopt_openreq(struct sock *newsk, const struct sock *oldsk, struct request_sock *req)
+{
+ struct tcp_authopt_info *old_info;
+ struct tcp_authopt_info *new_info;
+ int err;
+
+ old_info = rcu_dereference(tcp_sk(oldsk)->authopt_info);
+ if (!old_info)
+ return 0;
+
+ new_info = kmalloc(sizeof(*new_info), GFP_KERNEL | __GFP_ZERO);
+ if (!new_info)
+ return -ENOMEM;
+
+ sk_nocaps_add(newsk, NETIF_F_GSO_MASK);
+ new_info->src_isn = tcp_rsk(req)->snt_isn;
+ new_info->dst_isn = tcp_rsk(req)->rcv_isn;
+ new_info->local_send_id = old_info->local_send_id;
+ INIT_HLIST_HEAD(&new_info->head);
+ err = tcp_authopt_clone_keys(newsk, oldsk, new_info, old_info);
+ if (err) {
+ __tcp_authopt_info_free(newsk, new_info);
+ return err;
+ }
+ rcu_assign_pointer(tcp_sk(newsk)->authopt_info, new_info);
+
+ return 0;
+}
+
+/* feed traffic key into shash */
+static int tcp_authopt_shash_traffic_key(struct shash_desc *desc,
+ struct sock *sk,
+ struct sk_buff *skb,
+ bool input,
+ bool ipv6)
+{
+ struct tcphdr *th = tcp_hdr(skb);
+ int err;
+ __be32 sisn, disn;
+
+ // RFC5926 section 3.1.1.1
+ err = crypto_shash_update(desc, "\x01TCP-AO", 7);
+ if (err)
+ return err;
+
+ /* Addresses from packet on input and from socket on output
+ * This is because on output MAC is computed before prepending IP header
+ */
+ if (input) {
+ if (ipv6)
+ err = crypto_shash_update(desc, (u8 *)&ipv6_hdr(skb)->saddr, 32);
+ else
+ err = crypto_shash_update(desc, (u8 *)&ip_hdr(skb)->saddr, 8);
+ if (err)
+ return err;
+ } else {
+ if (ipv6) {
+ struct in6_addr *saddr;
+ struct in6_addr *daddr;
+
+ saddr = &sk->sk_v6_rcv_saddr;
+ daddr = &sk->sk_v6_daddr;
+ err = crypto_shash_update(desc, (u8 *)&sk->sk_v6_rcv_saddr, 16);
+ if (err)
+ return err;
+ err = crypto_shash_update(desc, (u8 *)&sk->sk_v6_daddr, 16);
+ if (err)
+ return err;
+ } else {
+ err = crypto_shash_update(desc, (u8 *)&sk->sk_rcv_saddr, 4);
+ if (err)
+ return err;
+ err = crypto_shash_update(desc, (u8 *)&sk->sk_daddr, 4);
+ if (err)
+ return err;
+ }
+ }
+
+ /* TCP ports from header */
+ err = crypto_shash_update(desc, (u8 *)&th->source, 4);
+ if (err)
+ return err;
+
+ /* special cases for SYN and SYN/ACK */
+ if (th->syn && !th->ack) {
+ sisn = th->seq;
+ disn = 0;
+ } else if (th->syn && th->ack) {
+ sisn = th->seq;
+ disn = htonl(ntohl(th->ack_seq) - 1);
+ } else {
+ struct tcp_authopt_info *authopt_info = rcu_dereference(tcp_sk(sk)->authopt_info);
+ /* authopt was removed from under us, maybe socket deleted? */
+ /* should pass this as an argument instead */
+ if (!authopt_info)
+ return -EINVAL;
+ /* Initial sequence numbers for ESTABLISHED connections from info */
+ if (input) {
+ sisn = htonl(authopt_info->dst_isn);
+ disn = htonl(authopt_info->src_isn);
+ } else {
+ sisn = htonl(authopt_info->src_isn);
+ disn = htonl(authopt_info->dst_isn);
+ }
+ }
+
+ err = crypto_shash_update(desc, (u8 *)&sisn, 4);
+ if (err)
+ return err;
+ err = crypto_shash_update(desc, (u8 *)&disn, 4);
+ if (err)
+ return err;
+
+ /* This hardcodes sha1 digestsize in bits: */
+ err = crypto_shash_update(desc, "\x00\xa0", 2);
+ if (err)
+ return err;
+
+ return 0;
+}
+
+static int tcp_authopt_get_traffic_key(struct sock *sk,
+ struct sk_buff *skb,
+ struct tcp_authopt_key_info *key,
+ bool input,
+ bool ipv6,
+ u8 *traffic_key)
+{
+ SHASH_DESC_ON_STACK(desc, kdf_tfm);
+ struct crypto_shash *kdf_tfm;
+ int err;
+
+ if (key->alg == TCP_AUTHOPT_ALG_HMAC_SHA_1_96)
+ kdf_tfm = crypto_alloc_shash("hmac(sha1)", 0, 0);
+ else
+ return -EINVAL;
+ if (IS_ERR(kdf_tfm))
+ return PTR_ERR(kdf_tfm);
+ if (WARN_ON(crypto_shash_digestsize(kdf_tfm) != key->traffic_key_len)) {
+ err = -ENOBUFS;
+ goto out;
+ }
+
+ err = crypto_shash_setkey(kdf_tfm, key->key, key->keylen);
+ if (err)
+ goto out;
+
+ desc->tfm = kdf_tfm;
+ err = crypto_shash_init(desc);
+ if (err)
+ goto out;
+
+ err = tcp_authopt_shash_traffic_key(desc, sk, skb, input, ipv6);
+ if (err)
+ goto out;
+
+ err = crypto_shash_final(desc, traffic_key);
+ if (err)
+ goto out;
+ //printk("traffic_key: %*phN\n", 20, traffic_key);
+
+out:
+ crypto_free_shash(kdf_tfm);
+ return err;
+}
+
+static int crypto_shash_update_zero(struct shash_desc *desc, int len)
+{
+ u8 zero = 0;
+ int i, err;
+
+ for (i = 0; i < len; ++i) {
+ err = crypto_shash_update(desc, &zero, 1);
+ if (err)
+ return err;
+ }
+
+ return 0;
+}
+
+static int tcp_authopt_hash_tcp4_pseudoheader(struct shash_desc *desc,
+ __be32 saddr,
+ __be32 daddr,
+ int nbytes)
+{
+ struct tcp4_pseudohdr phdr = {
+ .saddr = saddr,
+ .daddr = daddr,
+ .pad = 0,
+ .protocol = IPPROTO_TCP,
+ .len = htons(nbytes)
+ };
+ return crypto_shash_update(desc, (u8 *)&phdr, sizeof(phdr));
+}
+
+static int tcp_authopt_hash_tcp6_pseudoheader(struct shash_desc *desc,
+ struct in6_addr *saddr,
+ struct in6_addr *daddr,
+ u32 plen)
+{
+ int err;
+ u32 buf[2];
+
+ buf[0] = htonl(plen);
+ buf[1] = htonl(IPPROTO_TCP);
+
+ err = crypto_shash_update(desc, (u8 *)saddr, sizeof(*saddr));
+ if (err)
+ return err;
+ err = crypto_shash_update(desc, (u8 *)daddr, sizeof(*daddr));
+ if (err)
+ return err;
+ return crypto_shash_update(desc, (u8 *)&buf, sizeof(buf));
+}
+
+/* TCP authopt as found in header */
+struct tcphdr_authopt {
+ u8 num;
+ u8 len;
+ u8 keyid;
+ u8 rnextkeyid;
+ u8 mac[0];
+};
+
+/* Find TCP_AUTHOPT in header.
+ *
+ * Returns pointer to TCP_AUTHOPT or NULL if not found.
+ */
+static u8 *tcp_authopt_find_option(struct tcphdr *th)
+{
+ int length = (th->doff << 2) - sizeof(*th);
+ u8 *ptr = (u8 *)(th + 1);
+
+ while (length >= 2) {
+ int opcode = *ptr++;
+ int opsize;
+
+ switch (opcode) {
+ case TCPOPT_EOL:
+ return NULL;
+ case TCPOPT_NOP:
+ length--;
+ continue;
+ default:
+ if (length < 2)
+ return NULL;
+ opsize = *ptr++;
+ if (opsize < 2)
+ return NULL;
+ if (opsize > length)
+ return NULL;
+ if (opcode == TCPOPT_AUTHOPT)
+ return ptr - 2;
+ }
+ ptr += opsize - 2;
+ length -= opsize;
+ }
+ return NULL;
+}
+
+/** Hash tcphdr options.
+ * If include_options is false then only the TCPOPT_AUTHOPT option itself is hashed
+ * Maybe we could skip option parsing by assuming the AUTHOPT header is at hash_location-4?
+ */
+static int tcp_authopt_hash_opts(struct shash_desc *desc,
+ struct tcphdr *th,
+ bool include_options)
+{
+ int err;
+ /* start of options */
+ u8 *tcp_opts = (u8 *)(th + 1);
+ /* end of options */
+ u8 *tcp_data = ((u8 *)th) + th->doff * 4;
+ /* pointer to TCPOPT_AUTHOPT */
+ u8 *authopt_ptr = tcp_authopt_find_option(th);
+ u8 authopt_len;
+
+ if (!authopt_ptr)
+ return -EINVAL;
+ authopt_len = *(authopt_ptr + 1);
+
+ if (include_options) {
+ err = crypto_shash_update(desc, tcp_opts, authopt_ptr - tcp_opts + 4);
+ if (err)
+ return err;
+ err = crypto_shash_update_zero(desc, authopt_len - 4);
+ if (err)
+ return err;
+ err = crypto_shash_update(desc,
+ authopt_ptr + authopt_len,
+ tcp_data - (authopt_ptr + authopt_len));
+ if (err)
+ return err;
+ } else {
+ err = crypto_shash_update(desc, authopt_ptr, 4);
+ if (err)
+ return err;
+ err = crypto_shash_update_zero(desc, authopt_len - 4);
+ if (err)
+ return err;
+ }
+
+ return 0;
+}
+
+static int skb_shash_frags(struct shash_desc *desc,
+ struct sk_buff *skb)
+{
+ struct sk_buff *frag_iter;
+ int err, i;
+
+ for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+ skb_frag_t *f = &skb_shinfo(skb)->frags[i];
+ u32 p_off, p_len, copied;
+ struct page *p;
+ u8 *vaddr;
+
+ skb_frag_foreach_page(f, skb_frag_off(f), skb_frag_size(f),
+ p, p_off, p_len, copied) {
+ vaddr = kmap_atomic(p);
+ err = crypto_shash_update(desc, vaddr + p_off, p_len);
+ kunmap_atomic(vaddr);
+ if (err)
+ return err;
+ }
+ }
+
+ skb_walk_frags(skb, frag_iter) {
+ err = skb_shash_frags(desc, frag_iter);
+ if (err)
+ return err;
+ }
+
+ return 0;
+}
+
+static int tcp_authopt_hash_packet(struct crypto_shash *tfm,
+ struct sock *sk,
+ struct sk_buff *skb,
+ bool input,
+ bool ipv6,
+ bool include_options,
+ u8 *macbuf)
+{
+ struct tcphdr *th = tcp_hdr(skb);
+ SHASH_DESC_ON_STACK(desc, tfm);
+ int err;
+
+ /* NOTE: SNE unimplemented */
+ __be32 sne = 0;
+
+ desc->tfm = tfm;
+ err = crypto_shash_init(desc);
+ if (err)
+ return err;
+
+ err = crypto_shash_update(desc, (u8 *)&sne, 4);
+ if (err)
+ return err;
+
+ if (ipv6) {
+ struct in6_addr *saddr;
+ struct in6_addr *daddr;
+
+ if (input) {
+ saddr = &ipv6_hdr(skb)->saddr;
+ daddr = &ipv6_hdr(skb)->daddr;
+ } else {
+ saddr = &sk->sk_v6_rcv_saddr;
+ daddr = &sk->sk_v6_daddr;
+ }
+ err = tcp_authopt_hash_tcp6_pseudoheader(desc, saddr, daddr, skb->len);
+ if (err)
+ return err;
+ } else {
+ __be32 saddr;
+ __be32 daddr;
+
+ if (input) {
+ saddr = ip_hdr(skb)->saddr;
+ daddr = ip_hdr(skb)->daddr;
+ } else {
+ saddr = sk->sk_rcv_saddr;
+ daddr = sk->sk_daddr;
+ }
+ err = tcp_authopt_hash_tcp4_pseudoheader(desc, saddr, daddr, skb->len);
+ if (err)
+ return err;
+ }
+
+ // TCP header with checksum set to zero
+ {
+ struct tcphdr hashed_th = *th;
+
+ hashed_th.check = 0;
+ err = crypto_shash_update(desc, (u8 *)&hashed_th, sizeof(hashed_th));
+ if (err)
+ return err;
+ }
+
+ // TCP options
+ err = tcp_authopt_hash_opts(desc, th, include_options);
+ if (err)
+ return err;
+
+ // Rest of SKB->data
+ err = crypto_shash_update(desc, (u8 *)th + th->doff * 4, skb_headlen(skb) - th->doff * 4);
+ if (err)
+ return err;
+
+ err = skb_shash_frags(desc, skb);
+ if (err)
+ return err;
+
+ return crypto_shash_final(desc, macbuf);
+}
+
+int __tcp_authopt_calc_mac(struct sock *sk,
+ struct sk_buff *skb,
+ struct tcp_authopt_key_info *key,
+ bool input,
+ char *macbuf)
+{
+ struct crypto_shash *mac_tfm;
+ u8 traffic_key[TCP_AUTHOPT_MAX_TRAFFIC_KEY_LEN];
+ int err;
+ bool ipv6 = (sk->sk_family != AF_INET);
+
+ if (sk->sk_family != AF_INET && sk->sk_family != AF_INET6)
+ return -EINVAL;
+ if (WARN_ON(key->traffic_key_len > sizeof(traffic_key)))
+ return -ENOBUFS;
+
+ err = tcp_authopt_get_traffic_key(sk, skb, key, input, ipv6, traffic_key);
+ if (err)
+ return err;
+
+ if (key->alg == TCP_AUTHOPT_ALG_HMAC_SHA_1_96)
+ mac_tfm = crypto_alloc_shash("hmac(sha1)", 0, 0);
+ else
+ return -EINVAL;
+ if (IS_ERR(mac_tfm))
+ return PTR_ERR(mac_tfm);
+ if (crypto_shash_digestsize(mac_tfm) > TCP_AUTHOPT_MAXMACBUF) {
+ err = -EINVAL;
+ goto out;
+ }
+ err = crypto_shash_setkey(mac_tfm, traffic_key, key->traffic_key_len);
+ if (err)
+ goto out;
+
+ err = tcp_authopt_hash_packet(mac_tfm,
+ sk,
+ skb,
+ input,
+ ipv6,
+ !(key->flags & TCP_AUTHOPT_KEY_EXCLUDE_OPTS),
+ macbuf);
+ //printk("mac: %*phN\n", key->maclen, macbuf);
+
+out:
+ crypto_free_shash(mac_tfm);
+ return err;
+}
+
+int tcp_authopt_hash(char *hash_location,
+ struct tcp_authopt_key_info *key,
+ struct sock *sk,
+ struct sk_buff *skb)
+{
+ /* MAC inside option is truncated to 12 bytes but crypto API needs output
+ * buffer to be large enough so we use a buffer on the stack.
+ */
+ u8 macbuf[TCP_AUTHOPT_MAXMACBUF];
+ int err;
+
+ if (WARN_ON(key->maclen > sizeof(macbuf)))
+ return -ENOBUFS;
+
+ err = __tcp_authopt_calc_mac(sk, skb, key, false, macbuf);
+ if (err) {
+ memset(hash_location, 0, key->maclen);
+ return err;
+ }
+ memcpy(hash_location, macbuf, key->maclen);
+
+ return 0;
+}
+
+static struct tcp_authopt_key_info *tcp_authopt_inbound_key_lookup(struct sock *sk,
+ struct tcp_authopt_info *info,
+ u8 recv_id)
+{
+ struct tcp_authopt_key_info *key;
+
+ /* multiple matches will cause occasional failures */
+ hlist_for_each_entry_rcu(key, &info->head, node, 0)
+ if (key->recv_id == recv_id)
+ return key;
+
+ return NULL;
+}
+
+int __tcp_authopt_inbound_check(struct sock *sk, struct sk_buff *skb, struct tcp_authopt_info *info)
+{
+ struct tcphdr *th = (struct tcphdr *)skb_transport_header(skb);
+ struct tcphdr_authopt *opt = (struct tcphdr_authopt *)tcp_authopt_find_option(th);
+ struct tcp_authopt_key_info *key;
+ u8 macbuf[16];
+ int err;
+
+ /* wrong, should reject if missing key: */
+ if (!opt)
+ return 0;
+
+ key = tcp_authopt_inbound_key_lookup(sk, info, opt->keyid);
+ /* bad inbound key len */
+ if (key->maclen + 4 != opt->len)
+ return -EINVAL;
+
+ err = __tcp_authopt_calc_mac(sk, skb, key, true, macbuf);
+ if (err)
+ return err;
+
+ if (memcmp(macbuf, opt->mac, key->maclen)) {
+ NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPAUTHOPTFAILURE);
+ net_info_ratelimited("TCP Authentication Failed\n");
+ return -EINVAL;
+ }
+
+ return 0;
+}
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 149ceb5c94ff..9cd540c42d3f 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -70,10 +70,11 @@
#include <linux/sysctl.h>
#include <linux/kernel.h>
#include <linux/prefetch.h>
#include <net/dst.h>
#include <net/tcp.h>
+#include <net/tcp_authopt.h>
#include <net/inet_common.h>
#include <linux/ipsec.h>
#include <asm/unaligned.h>
#include <linux/errqueue.h>
#include <trace/events/tcp.h>
@@ -5935,18 +5936,34 @@ void tcp_init_transfer(struct sock *sk, int bpf_op, struct sk_buff *skb)
if (!icsk->icsk_ca_initialized)
tcp_init_congestion_control(sk);
tcp_init_buffer_space(sk);
}

+static void tcp_authopt_finish_connect(struct sock *sk, struct sk_buff *skb)
+{
+#ifdef CONFIG_TCP_AUTHOPT
+ struct tcp_authopt_info *info;
+
+ info = rcu_dereference_protected(tcp_sk(sk)->authopt_info, lockdep_sock_is_held(sk));
+ if (!info)
+ return;
+
+ info->src_isn = ntohl(tcp_hdr(skb)->ack_seq) - 1;
+ info->dst_isn = ntohl(tcp_hdr(skb)->seq);
+#endif
+}
+
void tcp_finish_connect(struct sock *sk, struct sk_buff *skb)
{
struct tcp_sock *tp = tcp_sk(sk);
struct inet_connection_sock *icsk = inet_csk(sk);

tcp_set_state(sk, TCP_ESTABLISHED);
icsk->icsk_ack.lrcvtime = tcp_jiffies32;

+ tcp_authopt_finish_connect(sk, skb);
+
if (skb) {
icsk->icsk_af_ops->sk_rx_dst_set(sk, skb);
security_inet_conn_established(sk, skb);
sk_mark_napi_id(sk, skb);
}
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index b9dc2d6197be..b0e25c6d40eb 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -60,10 +60,11 @@

#include <net/net_namespace.h>
#include <net/icmp.h>
#include <net/inet_hashtables.h>
#include <net/tcp.h>
+#include <net/tcp_authopt.h>
#include <net/transp_v6.h>
#include <net/ipv6.h>
#include <net/inet_common.h>
#include <net/timewait_sock.h>
#include <net/xfrm.h>
@@ -2059,10 +2060,13 @@ int tcp_v4_rcv(struct sk_buff *skb)
goto discard_and_relse;

if (tcp_v4_inbound_md5_hash(sk, skb, dif, sdif))
goto discard_and_relse;

+ if (tcp_authopt_inbound_check(sk, skb))
+ goto discard_and_relse;
+
nf_reset_ct(skb);

if (tcp_filter(sk, skb))
goto discard_and_relse;
th = (const struct tcphdr *)skb->data;
@@ -2256,10 +2260,11 @@ void tcp_v4_destroy_sock(struct sock *sk)
tcp_clear_md5_list(sk);
kfree_rcu(rcu_dereference_protected(tp->md5sig_info, 1), rcu);
tp->md5sig_info = NULL;
}
#endif
+ tcp_authopt_clear(sk);

/* Clean up a referenced TCP bind bucket. */
if (inet_csk(sk)->icsk_bind_hash)
inet_put_port(sk);

diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index 0a4f3f16140a..4d7d86547b0e 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -24,10 +24,11 @@
#include <linux/slab.h>
#include <linux/sysctl.h>
#include <linux/workqueue.h>
#include <linux/static_key.h>
#include <net/tcp.h>
+#include <net/tcp_authopt.h>
#include <net/inet_common.h>
#include <net/xfrm.h>
#include <net/busy_poll.h>

static bool tcp_in_window(u32 seq, u32 end_seq, u32 s_win, u32 e_win)
@@ -539,10 +540,11 @@ struct sock *tcp_create_openreq_child(const struct sock *sk,
#ifdef CONFIG_TCP_MD5SIG
newtp->md5sig_info = NULL; /*XXX*/
if (newtp->af_specific->md5_lookup(sk, newsk))
newtp->tcp_header_len += TCPOLEN_MD5SIG_ALIGNED;
#endif
+ tcp_authopt_openreq(newsk, sk, req);
if (skb->len >= TCP_MSS_DEFAULT + newtp->tcp_header_len)
newicsk->icsk_ack.last_seg_size = skb->len - newtp->tcp_header_len;
newtp->rx_opt.mss_clamp = req->mss;
tcp_ecn_openreq_child(newtp, req);
newtp->fastopen_req = NULL;
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 29553fce8502..2a680acca73d 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -37,10 +37,11 @@

#define pr_fmt(fmt) "TCP: " fmt

#include <net/tcp.h>
#include <net/mptcp.h>
+#include <net/tcp_authopt.h>

#include <linux/compiler.h>
#include <linux/gfp.h>
#include <linux/module.h>
#include <linux/static_key.h>
@@ -411,10 +412,11 @@ static inline bool tcp_urg_mode(const struct tcp_sock *tp)

#define OPTION_SACK_ADVERTISE (1 << 0)
#define OPTION_TS (1 << 1)
#define OPTION_MD5 (1 << 2)
#define OPTION_WSCALE (1 << 3)
+#define OPTION_AUTHOPT (1 << 4)
#define OPTION_FAST_OPEN_COOKIE (1 << 8)
#define OPTION_SMC (1 << 9)
#define OPTION_MPTCP (1 << 10)

static void smc_options_write(__be32 *ptr, u16 *options)
@@ -435,16 +437,21 @@ static void smc_options_write(__be32 *ptr, u16 *options)
struct tcp_out_options {
u16 options; /* bit field of OPTION_* */
u16 mss; /* 0 to disable */
u8 ws; /* window scale, 0 to disable */
u8 num_sack_blocks; /* number of SACK blocks to include */
- u8 hash_size; /* bytes in hash_location */
u8 bpf_opt_len; /* length of BPF hdr option */
+#ifdef CONFIG_TCP_AUTHOPT
+ u8 authopt_rnextkeyid;
+#endif
__u8 *hash_location; /* temporary pointer, overloaded */
__u32 tsval, tsecr; /* need to include OPTION_TS */
struct tcp_fastopen_cookie *fastopen_cookie; /* Fast open cookie */
struct mptcp_out_options mptcp;
+#ifdef CONFIG_TCP_AUTHOPT
+ struct tcp_authopt_key_info *authopt_key;
+#endif
};

static void mptcp_options_write(__be32 *ptr, const struct tcp_sock *tp,
struct tcp_out_options *opts)
{
@@ -617,10 +624,24 @@ static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp,
/* overload cookie hash location */
opts->hash_location = (__u8 *)ptr;
ptr += 4;
}

+#ifdef CONFIG_TCP_AUTHOPT
+ if (unlikely(OPTION_AUTHOPT & options)) {
+ struct tcp_authopt_key_info *key = opts->authopt_key;
+
+ WARN_ON(!key);
+ *ptr++ = htonl((TCPOPT_AUTHOPT << 24) | ((4 + key->maclen) << 16) |
+ (key->send_id << 8) | opts->authopt_rnextkeyid);
+ /* overload cookie hash location */
+ opts->hash_location = (__u8 *)ptr;
+ /* maclen is currently always 12 but try to align nicely anyway. */
+ ptr += (key->maclen + 3) / 4;
+ }
+#endif
+
if (unlikely(opts->mss)) {
*ptr++ = htonl((TCPOPT_MSS << 24) |
(TCPOLEN_MSS << 16) |
opts->mss);
}
@@ -752,10 +773,37 @@ static void mptcp_set_option_cond(const struct request_sock *req,
}
}
}
}

+static int tcp_authopt_init_options(const struct sock *sk,
+ struct tcp_out_options *opts)
+{
+#ifdef CONFIG_TCP_AUTHOPT
+ struct tcp_authopt_info *info;
+ struct tcp_authopt_key_info *key;
+
+ info = rcu_dereference_check(tcp_sk(sk)->authopt_info, lockdep_sock_is_held(sk));
+
+ if (!info)
+ return 0;
+
+ if (!info->local_send_id)
+ return 0;
+
+ key = tcp_authopt_key_info_lookup((struct sock *)sk, info->local_send_id);
+ if (key) {
+ opts->options |= OPTION_AUTHOPT;
+ opts->authopt_key = key;
+ opts->authopt_rnextkeyid = info->rnextkeyid;
+ return 4 + key->maclen;
+ }
+#endif
+
+ return 0;
+}
+
/* Compute TCP options for SYN packets. This is not the final
* network wire format yet.
*/
static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb,
struct tcp_out_options *opts,
@@ -774,10 +822,11 @@ static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb,
opts->options |= OPTION_MD5;
remaining -= TCPOLEN_MD5SIG_ALIGNED;
}
}
#endif
+ remaining -= tcp_authopt_init_options(sk, opts);

/* We always get an MSS option. The option bytes which will be seen in
* normal data packets should timestamps be used, must be in the MSS
* advertised. But we subtract them from tp->mss_cache so that
* calculations in tcp_sendmsg are simpler etc. So account for this
@@ -862,10 +911,11 @@ static unsigned int tcp_synack_options(const struct sock *sk,
*/
if (synack_type != TCP_SYNACK_COOKIE)
ireq->tstamp_ok &= !ireq->sack_ok;
}
#endif
+ remaining -= tcp_authopt_init_options(sk, opts);

/* We always send an MSS option. */
opts->mss = mss;
remaining -= TCPOLEN_MSS_ALIGNED;

@@ -930,10 +980,11 @@ static unsigned int tcp_established_options(struct sock *sk, struct sk_buff *skb
opts->options |= OPTION_MD5;
size += TCPOLEN_MD5SIG_ALIGNED;
}
}
#endif
+ size += tcp_authopt_init_options(sk, opts);

if (likely(tp->rx_opt.tstamp_ok)) {
opts->options |= OPTION_TS;
opts->tsval = skb ? tcp_skb_timestamp(skb) + tp->tsoffset : 0;
opts->tsecr = tp->rx_opt.ts_recent;
@@ -1365,10 +1416,17 @@ static int __tcp_transmit_skb(struct sock *sk, struct sk_buff *skb,
sk_nocaps_add(sk, NETIF_F_GSO_MASK);
tp->af_specific->calc_md5_hash(opts.hash_location,
md5, sk, skb);
}
#endif
+#ifdef CONFIG_TCP_AUTHOPT
+ if (opts.authopt_key) {
+ sk_nocaps_add(sk, NETIF_F_GSO_MASK);
+ err = tcp_authopt_hash(opts.hash_location, opts.authopt_key, sk, skb);
+ WARN_ON(err); // FIXME
+ }
+#endif

/* BPF prog is the last one writing header option */
bpf_skops_write_hdr_opt(sk, skb, NULL, NULL, 0, &opts);

INDIRECT_CALL_INET(icsk->icsk_af_ops->send_check,
@@ -3602,10 +3660,15 @@ struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,
if (md5)
tcp_rsk(req)->af_specific->calc_md5_hash(opts.hash_location,
md5, req_to_sk(req), skb);
rcu_read_unlock();
#endif
+#ifdef CONFIG_TCP_AUTHOPT
+ /* If signature fails we do nothing */
+ if (opts.authopt_key)
+ tcp_authopt_hash(opts.hash_location, opts.authopt_key, req_to_sk(req), skb);
+#endif

bpf_skops_write_hdr_opt((struct sock *)sk, skb, req, syn_skb,
synack_type, &opts);

skb->skb_mstamp_ns = now;

base-commit: 0d6835ffe50c9c1f098b5704394331710b67af48
--
2.25.1