[PATCH v3 07/36] tcp: Add TCP-AO config and structures

Dmitry Safonov
2022-10-27T20:44:52Z

Introduce new kernel config option and common structures as well as
helpers to be used by TCP-AO code.

Co-developed-by: Francesco Ruggeri <fruggeri@arista.com>
Signed-off-by: Francesco Ruggeri <fruggeri@arista.com>
Co-developed-by: Salam Noureddine <noureddine@arista.com>
Signed-off-by: Salam Noureddine <noureddine@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
include/linux/tcp.h | 9 +++-
include/net/tcp.h | 8 +---
include/net/tcp_ao.h | 90 ++++++++++++++++++++++++++++++++++++++++
include/uapi/linux/tcp.h | 2 +
net/ipv4/Kconfig | 12 ++++++
5 files changed, 113 insertions(+), 8 deletions(-)
create mode 100644 include/net/tcp_ao.h

diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 41b1da621a45..fd248875b0a9 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -434,13 +434,18 @@ struct tcp_sock {
bool syn_smc; /* SYN includes SMC */
#endif

-#ifdef CONFIG_TCP_MD5SIG
-/* TCP AF-Specific parts; only used by MD5 Signature support so far */
+#if defined(CONFIG_TCP_MD5SIG) || defined(CONFIG_TCP_AO)
+/* TCP AF-Specific parts; only used by TCP-AO/MD5 Signature support so far */
const struct tcp_sock_af_ops *af_specific;

+#ifdef CONFIG_TCP_MD5SIG
/* TCP MD5 Signature Option information */
struct tcp_md5sig_info __rcu *md5sig_info;
#endif
+#ifdef CONFIG_TCP_AO
+ struct tcp_ao_info __rcu *ao_info;
+#endif
+#endif

/* TCP fastopen related information */
struct tcp_fastopen_request *fastopen_req;
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 03dbe1940fec..3395a925dc6e 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -37,6 +37,7 @@
#include <net/snmp.h>
#include <net/ip.h>
#include <net/tcp_states.h>
+#include <net/tcp_ao.h>
#include <net/inet_ecn.h>
#include <net/dst.h>
#include <net/mptcp.h>
@@ -1615,12 +1616,7 @@ static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
tp->retransmit_skb_hint = NULL;
}

-union tcp_md5_addr {
- struct in_addr a4;
-#if IS_ENABLED(CONFIG_IPV6)
- struct in6_addr a6;
-#endif
-};
+#define tcp_md5_addr tcp_ao_addr

/* - key database */
struct tcp_md5sig_key {
diff --git a/include/net/tcp_ao.h b/include/net/tcp_ao.h
new file mode 100644
index 000000000000..39b3fc31e5a1
--- /dev/null
+++ b/include/net/tcp_ao.h
@@ -0,0 +1,90 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef _TCP_AO_H
+#define _TCP_AO_H
+
+#define TCP_AO_MAX_HASH_SIZE 64
+#define TCP_AO_KEY_ALIGN 1
+#define __tcp_ao_key_align __aligned(TCP_AO_KEY_ALIGN)
+
+union tcp_ao_addr {
+ struct in_addr a4;
+#if IS_ENABLED(CONFIG_IPV6)
+ struct in6_addr a6;
+#endif
+};
+
+struct tcp_ao_hdr {
+ u8 kind;
+ u8 length;
+ u8 keyid;
+ u8 rnext_keyid;
+};
+
+struct tcp_ao_key {
+ struct hlist_node node;
+ union tcp_ao_addr addr;
+ u8 key[TCP_AO_MAXKEYLEN] __tcp_ao_key_align;
+ unsigned int crypto_pool_id;
+ u16 port;
+ u8 prefixlen;
+ u8 family;
+ u8 keylen;
+ u8 keyflags;
+ u8 sndid;
+ u8 rcvid;
+ u8 maclen;
+ u8 digest_size;
+ struct rcu_head rcu;
+ u8 traffic_keys[];
+};
+
+static inline u8 *rcv_other_key(struct tcp_ao_key *key)
+{
+ return key->traffic_keys;
+}
+
+static inline u8 *snd_other_key(struct tcp_ao_key *key)
+{
+ return key->traffic_keys + key->digest_size;
+}
+
+static inline int tcp_ao_maclen(const struct tcp_ao_key *key)
+{
+ return key->maclen;
+}
+
+static inline int tcp_ao_sizeof_key(const struct tcp_ao_key *key)
+{
+ return sizeof(struct tcp_ao_key) + (TCP_AO_MAX_HASH_SIZE << 1);
+}
+
+static inline int tcp_ao_len(const struct tcp_ao_key *key)
+{
+ return tcp_ao_maclen(key) + sizeof(struct tcp_ao_hdr);
+}
+
+static inline unsigned int tcp_ao_digest_size(struct tcp_ao_key *key)
+{
+ return key->digest_size;
+}
+
+struct tcp_ao_info {
+ struct hlist_head head;
+ struct rcu_head rcu;
+ /* current_key and rnext_key aren't maintained on listen sockets.
+ * Their purpose is to cache keys on established connections,
+ * saving needless lookups. Never dereference any of them from
+ * listen sockets.
+ */
+ struct tcp_ao_key *volatile current_key;
+ struct tcp_ao_key *rnext_key;
+ u8 ao_flags;
+ __be32 lisn;
+ __be32 risn;
+ u32 snd_sne;
+ u32 snd_sne_seq;
+ u32 rcv_sne;
+ u32 rcv_sne_seq;
+};
+
+#endif /* _TCP_AO_H */
diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h
index 8fc09e8638b3..849bbf2d3c38 100644
--- a/include/uapi/linux/tcp.h
+++ b/include/uapi/linux/tcp.h
@@ -342,6 +342,8 @@ struct tcp_diag_md5sig {
__u8 tcpm_key[TCP_MD5SIG_MAXKEYLEN];
};

+#define TCP_AO_MAXKEYLEN 80
+
/* setsockopt(fd, IPPROTO_TCP, TCP_ZEROCOPY_RECEIVE, ...) */

#define TCP_RECEIVE_ZEROCOPY_FLAG_TLB_CLEAN_HINT 0x1
diff --git a/net/ipv4/Kconfig b/net/ipv4/Kconfig
index c341864e4398..4a78f3e0199e 100644
--- a/net/ipv4/Kconfig
+++ b/net/ipv4/Kconfig
@@ -731,6 +731,18 @@ config DEFAULT_TCP_CONG
default "bbr" if DEFAULT_BBR
default "cubic"

+config TCP_AO
+ bool "TCP: Authentication Option (RFC5925)"
+ select CRYPTO
+ select CRYPTO_POOL
+ depends on 64BIT # seq-number extension needs WRITE_ONCE(u64)
+ default y
+ help
+ TCP-AO specifies the use of stronger Message Authentication Codes (MACs),
+ protects against replays for long-lived TCP connections, and
+ provides more details on the association of security with TCP
+ connections than TCP MD5 (See RFC5925)
+
config TCP_MD5SIG
bool "TCP: MD5 Signature Option support (RFC2385)"
select CRYPTO_POOL
--
2.38.1