tcp: extend TCP flags to allow AE bit/ACE field

With AccECN, there's one additional TCP flag to be used (AE)
and ACE field that overloads the definition of AE, CWR, and
ECE flags. As tcp_flags was previously only 1 byte, the
byte-order stuff needs to be added to it's handling.

Signed-off-by: Ilpo Järvinen <[e-mail]>
Signed-off-by: Chia-Yu Chang <[e-mail]>
Reviewed-by: Eric Dumazet <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/net/tcp.h

···
 #define TCPHDR_URG	BIT(5)
 #define TCPHDR_ECE	BIT(6)
 #define TCPHDR_CWR	BIT(7)
+#define TCPHDR_AE	BIT(8)
+#define TCPHDR_FLAGS_MASK (TCPHDR_FIN | TCPHDR_SYN | TCPHDR_RST | \
+			   TCPHDR_PSH | TCPHDR_ACK | TCPHDR_URG | \
+			   TCPHDR_ECE | TCPHDR_CWR | TCPHDR_AE)
+#define tcp_flags_ntohs(th) (ntohs(*(__be16 *)&tcp_flag_word(th)) & \
+			    TCPHDR_FLAGS_MASK)
 
+#define TCPHDR_ACE (TCPHDR_ECE | TCPHDR_CWR | TCPHDR_AE)
 #define TCPHDR_SYN_ECN	(TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR)
 
 /* State flags for sacked in struct tcp_skb_cb */
···
 			u16	tcp_gso_size;
 		};
 	};
-	__u8		tcp_flags;	/* TCP header flags. (tcp[13])	*/
+	__u16		tcp_flags;	/* TCP header flags (tcp[12-13])*/
 
 	__u8		sacked;		/* State flags for SACK.	*/
 	__u8		ip_dsfield;	/* IPv4 tos or IPv6 dsfield	*/

include/uapi/linux/tcp.h

···
 	__be32	seq;
 	__be32	ack_seq;
 #if defined(__LITTLE_ENDIAN_BITFIELD)
-	__u16	res1:4,
+	__u16	ae:1,
+		res1:3,
 		doff:4,
 		fin:1,
 		syn:1,
···
 		cwr:1;
 #elif defined(__BIG_ENDIAN_BITFIELD)
 	__u16	doff:4,
-		res1:4,
+		res1:3,
+		ae:1,
 		cwr:1,
 		ece:1,
 		urg:1,
···
 #define tcp_flag_word(tp) (((union tcp_word_hdr *)(tp))->words[3])
 
 enum {
+	TCP_FLAG_AE  = __constant_cpu_to_be32(0x01000000),
 	TCP_FLAG_CWR = __constant_cpu_to_be32(0x00800000),
 	TCP_FLAG_ECE = __constant_cpu_to_be32(0x00400000),
 	TCP_FLAG_URG = __constant_cpu_to_be32(0x00200000),
···
 	TCP_FLAG_RST = __constant_cpu_to_be32(0x00040000),
 	TCP_FLAG_SYN = __constant_cpu_to_be32(0x00020000),
 	TCP_FLAG_FIN = __constant_cpu_to_be32(0x00010000),
-	TCP_RESERVED_BITS = __constant_cpu_to_be32(0x0F000000),
+	TCP_RESERVED_BITS = __constant_cpu_to_be32(0x0E000000),
 	TCP_DATA_OFFSET = __constant_cpu_to_be32(0xF0000000)
 };
 

net/ipv4/tcp_ipv4.c

···
 	TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin +
 				    skb->len - th->doff * 4);
 	TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq);
-	TCP_SKB_CB(skb)->tcp_flags = tcp_flag_byte(th);
+	TCP_SKB_CB(skb)->tcp_flags = tcp_flags_ntohs(th);
 	TCP_SKB_CB(skb)->ip_dsfield = ipv4_get_dsfield(iph);
 	TCP_SKB_CB(skb)->sacked	 = 0;
 	TCP_SKB_CB(skb)->has_rxtstamp =

net/ipv4/tcp_output.c

···
 /* Constructs common control bits of non-data skb. If SYN/FIN is present,
  * auto increment end seqno.
  */
-static void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags)
+static void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u16 flags)
 {
 	skb->ip_summed = CHECKSUM_PARTIAL;
 
···
 	th->seq			= htonl(tcb->seq);
 	th->ack_seq		= htonl(rcv_nxt);
 	*(((__be16 *)th) + 6)	= htons(((tcp_header_size >> 2) << 12) |
-					tcb->tcp_flags);
+					(tcb->tcp_flags & TCPHDR_FLAGS_MASK));
 
 	th->check		= 0;
 	th->urg_ptr		= 0;
···
 	struct sk_buff *buff;
 	int old_factor;
 	long limit;
+	u16 flags;
 	int nlen;
-	u8 flags;
 
 	if (WARN_ON(len > skb->len))
 		return -EINVAL;
···
 {
 	int nlen = skb->len - len;
 	struct sk_buff *buff;
-	u8 flags;
+	u16 flags;
 
 	/* All of a TSO frame must be composed of paged data.  */
 	DEBUG_NET_WARN_ON_ONCE(skb->len != skb->data_len);

net/ipv6/tcp_ipv6.c

···
 	TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin +
 				    skb->len - th->doff*4);
 	TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq);
-	TCP_SKB_CB(skb)->tcp_flags = tcp_flag_byte(th);
+	TCP_SKB_CB(skb)->tcp_flags = tcp_flags_ntohs(th);
 	TCP_SKB_CB(skb)->ip_dsfield = ipv6_get_dsfield(hdr);
 	TCP_SKB_CB(skb)->sacked = 0;
 	TCP_SKB_CB(skb)->has_rxtstamp =

net/netfilter/nf_log_syslog.c

···
 	/* Max length: 9 "RES=0x3C " */
 	nf_log_buf_add(m, "RES=0x%02x ", (u_int8_t)(ntohl(tcp_flag_word(th) &
 					    TCP_RESERVED_BITS) >> 22));
-	/* Max length: 32 "CWR ECE URG ACK PSH RST SYN FIN " */
+	/* Max length: 35 "AE CWR ECE URG ACK PSH RST SYN FIN " */
+	if (th->ae)
+		nf_log_buf_add(m, "AE ");
 	if (th->cwr)
 		nf_log_buf_add(m, "CWR ");
 	if (th->ece)
···
 
 	/* Proto    Max log string length */
 	/* IP:	    40+46+6+11+127 = 230 */
-	/* TCP:     10+max(25,20+30+13+9+32+11+127) = 252 */
+	/* TCP:     10+max(25,20+30+13+9+35+11+127) = 255 */
 	/* UDP:     10+max(25,20) = 35 */
 	/* UDPLITE: 14+max(25,20) = 39 */
 	/* ICMP:    11+max(25, 18+25+max(19,14,24+3+n+10,3+n+10)) = 91+n */
···
 
 	/* (ICMP allows recursion one level deep) */
 	/* maxlen =  IP + ICMP +  IP + max(TCP,UDP,ICMP,unknown) */
-	/* maxlen = 230+   91  + 230 + 252 = 803 */
+	/* maxlen = 230+   91  + 230 + 255 = 806 */
 }
 
 static noinline_for_stack void