net/tcp: Introduce TCP_AO setsockopt()s

Add 3 setsockopt()s:
1. TCP_AO_ADD_KEY to add a new Master Key Tuple (MKT) on a socket
2. TCP_AO_DEL_KEY to delete present MKT from a socket
3. TCP_AO_INFO to change flags, Current_key/RNext_key on a TCP-AO sk

Userspace has to introduce keys on every socket it wants to use TCP-AO
option on, similarly to TCP_MD5SIG/TCP_MD5SIG_EXT.
RFC5925 prohibits definition of MKTs that would match the same peer,
so do sanity checks on the data provided by userspace. Be as
conservative as possible, including refusal of defining MKT on
an established connection with no AO, removing the key in-use and etc.

(1) and (2) are to be used by userspace key manager to add/remove keys.
(3) main purpose is to set RNext_key, which (as prescribed by RFC5925)
is the KeyID that will be requested in TCP-AO header from the peer to
sign their segments with.

At this moment the life of ao_info ends in tcp_v4_destroy_sock().

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>
Acked-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 46 insertions, 0 deletions

diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h
index 74a1267baac5..fa49f03e62fe 100644
--- a/include/uapi/linux/tcp.h
+++ b/include/uapi/linux/tcp.h
@@ -129,6 +129,9 @@ enum {
 
 #define TCP_TX_DELAY		37	/* delay outgoing packets by XX usec */
 
+#define TCP_AO_ADD_KEY		38	/* Add/Set MKT */
+#define TCP_AO_DEL_KEY		39	/* Delete MKT */
+#define TCP_AO_INFO		40	/* Modify TCP-AO per-socket options */
 
 #define TCP_REPAIR_ON		1
 #define TCP_REPAIR_OFF		0
@@ -363,6 +366,49 @@ struct tcp_diag_md5sig {
 
 #define TCP_AO_MAXKEYLEN	80
 
+#define TCP_AO_KEYF_IFINDEX	(1 << 0)	/* L3 ifindex for VRF */
+
+struct tcp_ao_add { /* setsockopt(TCP_AO_ADD_KEY) */
+	struct __kernel_sockaddr_storage addr;	/* peer's address for the key */
+	char	alg_name[64];		/* crypto hash algorithm to use */
+	__s32	ifindex;		/* L3 dev index for VRF */
+	__u32   set_current	:1,	/* set key as Current_key at once */
+		set_rnext	:1,	/* request it from peer with RNext_key */
+		reserved	:30;	/* must be 0 */
+	__u16	reserved2;		/* padding, must be 0 */
+	__u8	prefix;			/* peer's address prefix */
+	__u8	sndid;			/* SendID for outgoing segments */
+	__u8	rcvid;			/* RecvID to match for incoming seg */
+	__u8	maclen;			/* length of authentication code (hash) */
+	__u8	keyflags;		/* see TCP_AO_KEYF_ */
+	__u8	keylen;			/* length of ::key */
+	__u8	key[TCP_AO_MAXKEYLEN];
+} __attribute__((aligned(8)));
+
+struct tcp_ao_del { /* setsockopt(TCP_AO_DEL_KEY) */
+	struct __kernel_sockaddr_storage addr;	/* peer's address for the key */
+	__s32	ifindex;		/* L3 dev index for VRF */
+	__u32   set_current	:1,	/* corresponding ::current_key */
+		set_rnext	:1,	/* corresponding ::rnext */
+		reserved	:30;	/* must be 0 */
+	__u16	reserved2;		/* padding, must be 0 */
+	__u8	prefix;			/* peer's address prefix */
+	__u8	sndid;			/* SendID for outgoing segments */
+	__u8	rcvid;			/* RecvID to match for incoming seg */
+	__u8	current_key;		/* KeyID to set as Current_key */
+	__u8	rnext;			/* KeyID to set as Rnext_key */
+	__u8	keyflags;		/* see TCP_AO_KEYF_ */
+} __attribute__((aligned(8)));
+
+struct tcp_ao_info_opt { /* setsockopt(TCP_AO_INFO) */
+	__u32   set_current	:1,	/* corresponding ::current_key */
+		set_rnext	:1,	/* corresponding ::rnext */
+		ao_required	:1,	/* don't accept non-AO connects */
+		reserved	:29;	/* must be 0 */
+	__u8	current_key;		/* KeyID to set as Current_key */
+	__u8	rnext;			/* KeyID to set as Rnext_key */
+} __attribute__((aligned(8)));
+
 /* setsockopt(fd, IPPROTO_TCP, TCP_ZEROCOPY_RECEIVE, ...) */
 
 #define TCP_RECEIVE_ZEROCOPY_FLAG_TLB_CLEAN_HINT 0x1