Subject: [PATCH net-next] net: skbuff: generalize the skb->decrypted bit

From: Jakub Kicinski <[email-masked]>
Date: Wed, 3 Apr 2024 13:21:39 -0700

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 <[email-masked]>
---
I'm going to post PSP support.. as soon as the test groundwork
is in place. I think this stands on its own as a cleanup.

CC: [email-masked]
CC: [email-masked]
CC: [email-masked]
---
 include/linux/skbuff.h | 15 ++++++++++++---
 include/net/sock.h     |  4 +---
 net/Kconfig            |  3 +++
 net/core/sock.c        |  5 ++---
 net/ipv4/tcp_input.c   | 12 +++---------
 net/ipv4/tcp_ipv4.c    |  4 +---
 net/ipv4/tcp_offload.c |  4 +---
 net/tls/Kconfig        |  1 +
 8 files changed, 24 insertions(+), 24 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 03ea36a82cdd..7dfb906d92f7 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -992,7 +992,7 @@ struct sk_buff {
 #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;
@@ -1615,17 +1615,26 @@ static inline void skb_copy_hash(struct sk_buff *to, const struct sk_buff *from)
 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
 }
diff --git a/include/net/sock.h b/include/net/sock.h
index 2253eefe2848..a495330c5c49 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -2835,12 +2835,10 @@ static inline struct sk_buff *sk_validate_xmit_skb(struct sk_buff *skb,
 
 	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
 
diff --git a/net/Kconfig b/net/Kconfig
index 3e57ccf0da27..d5ab791f7afa 100644
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -60,6 +60,9 @@ config NET_XGRESS
 config NET_REDIRECT
 	bool
 
+config SKB_DECRYPTED
+	bool
+
 config SKB_EXTENSIONS
 	bool
 
diff --git a/net/core/sock.c b/net/core/sock.c
index 5ed411231fc7..fe9195186c13 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -2526,13 +2526,12 @@ EXPORT_SYMBOL(skb_set_owner_w);
 
 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));
 }
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 1b6cd3840012..9fb9d704c4d9 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -4803,10 +4803,8 @@ static bool tcp_try_coalesce(struct sock *sk,
 	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;
@@ -5375,9 +5373,7 @@ tcp_collapse(struct sock *sk, struct sk_buff_head *list, struct rb_root *root,
 			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);
@@ -5407,10 +5403,8 @@ tcp_collapse(struct sock *sk, struct sk_buff_head *list, struct rb_root *root,
 				    !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
 			}
 		}
 	}
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 1e0a9762f92e..004e5d67c1d3 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2045,10 +2045,8 @@ bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb,
 	      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;
diff --git a/net/ipv4/tcp_offload.c b/net/ipv4/tcp_offload.c
index ebe4722bb020..fab0973f995b 100644
--- a/net/ipv4/tcp_offload.c
+++ b/net/ipv4/tcp_offload.c
@@ -265,9 +265,7 @@ struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb)
 		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;
diff --git a/net/tls/Kconfig b/net/tls/Kconfig
index 0cdc1f7b6b08..ce8d56a19187 100644
--- a/net/tls/Kconfig
+++ b/net/tls/Kconfig
@@ -20,6 +20,7 @@ config TLS
 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
-- 
2.44.0