net: skbuff: generalize the skb->decrypted bit

The ->decrypted bit can be reused for other crypto protocols.
Remove the direct dependency on TLS, add helpers to clean up
the ifdefs leaking out everywhere.

Signed-off-by: Jakub Kicinski <[e-mail]>
Reviewed-by: David Ahern <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/linux/skbuff.h

···
 #ifdef CONFIG_NETFILTER_SKIP_EGRESS
 	__u8			nf_skip_egress:1;
 #endif
-#ifdef CONFIG_TLS_DEVICE
+#ifdef CONFIG_SKB_DECRYPTED
 	__u8			decrypted:1;
 #endif
 	__u8			slow_gro:1;
···
 static inline int skb_cmp_decrypted(const struct sk_buff *skb1,
 				    const struct sk_buff *skb2)
 {
-#ifdef CONFIG_TLS_DEVICE
+#ifdef CONFIG_SKB_DECRYPTED
 	return skb2->decrypted - skb1->decrypted;
 #else
 	return 0;
 #endif
 }
 
+static inline bool skb_is_decrypted(const struct sk_buff *skb)
+{
+#ifdef CONFIG_SKB_DECRYPTED
+	return skb->decrypted;
+#else
+	return false;
+#endif
+}
+
 static inline void skb_copy_decrypted(struct sk_buff *to,
 				      const struct sk_buff *from)
 {
-#ifdef CONFIG_TLS_DEVICE
+#ifdef CONFIG_SKB_DECRYPTED
 	to->decrypted = from->decrypted;
 #endif
 }

include/net/sock.h

···
 
 	if (sk && sk_fullsock(sk) && sk->sk_validate_xmit_skb) {
 		skb = sk->sk_validate_xmit_skb(sk, dev, skb);
-#ifdef CONFIG_TLS_DEVICE
-	} else if (unlikely(skb->decrypted)) {
+	} else if (unlikely(skb_is_decrypted(skb))) {
 		pr_warn_ratelimited("unencrypted skb with no associated socket - dropping\n");
 		kfree_skb(skb);
 		skb = NULL;
-#endif
 	}
 #endif
 

net/Kconfig

···
 config NET_REDIRECT
 	bool
 
+config SKB_DECRYPTED
+	bool
+
 config SKB_EXTENSIONS
 	bool
 

net/core/sock.c

···
 
 static bool can_skb_orphan_partial(const struct sk_buff *skb)
 {
-#ifdef CONFIG_TLS_DEVICE
 	/* Drivers depend on in-order delivery for crypto offload,
 	 * partial orphan breaks out-of-order-OK logic.
 	 */
-	if (skb->decrypted)
+	if (skb_is_decrypted(skb))
 		return false;
-#endif
+
 	return (skb->destructor == sock_wfree ||
 		(IS_ENABLED(CONFIG_INET) && skb->destructor == tcp_wfree));
 }

net/ipv4/tcp_input.c

···
 	if (!mptcp_skb_can_collapse(to, from))
 		return false;
 
-#ifdef CONFIG_TLS_DEVICE
-	if (from->decrypted != to->decrypted)
+	if (skb_cmp_decrypted(from, to))
 		return false;
-#endif
 
 	if (!skb_try_coalesce(to, from, fragstolen, &delta))
 		return false;
···
 			break;
 
 		memcpy(nskb->cb, skb->cb, sizeof(skb->cb));
-#ifdef CONFIG_TLS_DEVICE
-		nskb->decrypted = skb->decrypted;
-#endif
+		skb_copy_decrypted(nskb, skb);
 		TCP_SKB_CB(nskb)->seq = TCP_SKB_CB(nskb)->end_seq = start;
 		if (list)
 			__skb_queue_before(list, skb, nskb);
···
 				    !mptcp_skb_can_collapse(nskb, skb) ||
 				    (TCP_SKB_CB(skb)->tcp_flags & (TCPHDR_SYN | TCPHDR_FIN)))
 					goto end;
-#ifdef CONFIG_TLS_DEVICE
-				if (skb->decrypted != nskb->decrypted)
+				if (skb_cmp_decrypted(skb, nskb))
 					goto end;
-#endif
 			}
 		}
 	}

net/ipv4/tcp_ipv4.c

···
 	      TCP_SKB_CB(skb)->tcp_flags) & TCPHDR_ACK) ||
 	    ((TCP_SKB_CB(tail)->tcp_flags ^
 	      TCP_SKB_CB(skb)->tcp_flags) & (TCPHDR_ECE | TCPHDR_CWR)) ||
-#ifdef CONFIG_TLS_DEVICE
-	    tail->decrypted != skb->decrypted ||
-#endif
 	    !mptcp_skb_can_collapse(tail, skb) ||
+	    skb_cmp_decrypted(tail, skb) ||
 	    thtail->doff != th->doff ||
 	    memcmp(thtail + 1, th + 1, hdrlen - sizeof(*th)))
 		goto no_coalesce;

net/ipv4/tcp_offload.c

···
 		flush |= (len - 1) >= mss;
 
 	flush |= (ntohl(th2->seq) + skb_gro_len(p)) ^ ntohl(th->seq);
-#ifdef CONFIG_TLS_DEVICE
-	flush |= p->decrypted ^ skb->decrypted;
-#endif
+	flush |= skb_cmp_decrypted(p, skb);
 
 	if (flush || skb_gro_receive(p, skb)) {
 		mss = 1;

net/tls/Kconfig

···
 config TLS_DEVICE
 	bool "Transport Layer Security HW offload"
 	depends on TLS
+	select SKB_DECRYPTED
 	select SOCK_VALIDATE_XMIT
 	select SOCK_RX_QUEUE_MAPPING
 	default n