[PATCH v4 nf-next 1/3] ipvs: add flags for per-service secure TCP state table

[Adriano Cordova <adrianox@gmail.com>]

Add IP_VS_SVC_F_SECURE_TCP to mark a virtual service for the
DoS-hardened TCP connection state table, and
IP_VS_CONN_F_SECURE_TCP to carry that capability on a connection
so the TCP state machine can select the hardened table for it.

The service flag is 0x0100: bits 0x0008/0x0010/0x0020 are the
scheduler bits, so leave 0x0040/0x0080 free for schedulers.

Set IP_VS_CONN_F_SECURE_TCP on every connection bound to a
destination whose service carries IP_VS_SVC_F_SECURE_TCP.

Signed-off-by: Adriano Cordova <adrianox@gmail.com>
---
Changes in v2:
- Let IP_VS_SVC_F_SECURE_TCP be 0x0100, leaving 0x0040/0x0080 free for
  scheduler flags.
- Let IP_VS_CONN_F_SECURE_TCP be (1 << 17) and drop it from
  IP_VS_CONN_F_BACKUP_MASK.
- Set the flag in ip_vs_bind_dest() instead of at every ip_vs_conn_new()
  call site.

Changes in v3:
- Merge the uapi flag definition and the ip_vs_bind_dest() stamping into
  a single patch.

(no changes since v3)

 include/uapi/linux/ip_vs.h      | 2 ++
 net/netfilter/ipvs/ip_vs_conn.c | 4 ++++
 net/netfilter/ipvs/ip_vs_core.c | 3 +++
 3 files changed, 9 insertions(+)

diff --git a/include/uapi/linux/ip_vs.h b/include/uapi/linux/ip_vs.h
index 2c37c6ac7525..ade170109ff4 100644
--- a/include/uapi/linux/ip_vs.h
+++ b/include/uapi/linux/ip_vs.h
@@ -27,6 +27,7 @@
 
 #define IP_VS_SVC_F_SCHED_SH_FALLBACK	IP_VS_SVC_F_SCHED1 /* SH fallback */
 #define IP_VS_SVC_F_SCHED_SH_PORT	IP_VS_SVC_F_SCHED2 /* SH use port */
+#define IP_VS_SVC_F_SECURE_TCP	0x0100		/* use the hardened TCP table */
 
 /*
  *      IPVS sync daemon states
@@ -105,6 +106,7 @@
 
 /* Flags that are not sent to backup server start from bit 16 */
 #define IP_VS_CONN_F_NFCT	(1 << 16)	/* use netfilter conntrack */
+#define IP_VS_CONN_F_SECURE_TCP	(1 << 17)	/* use the hardened TCP table */
 
 /* Connection flags from destination that can be changed by user space */
 #define IP_VS_CONN_F_DEST_MASK (IP_VS_CONN_F_FWD_MASK | \
diff --git a/net/netfilter/ipvs/ip_vs_conn.c b/net/netfilter/ipvs/ip_vs_conn.c
index 6fa3e1dc534c..0b465298b64b 100644
--- a/net/netfilter/ipvs/ip_vs_conn.c
+++ b/net/netfilter/ipvs/ip_vs_conn.c
@@ -1090,6 +1090,7 @@ ip_vs_bind_dest(struct ip_vs_conn *cp, struct ip_vs_dest *dest)
 {
 	unsigned int conn_flags;
 	__u32 flags;
+	struct ip_vs_service *svc;
 
 	/* if dest is NULL, then return directly */
 	if (!dest)
@@ -1102,6 +1103,9 @@ ip_vs_bind_dest(struct ip_vs_conn *cp, struct ip_vs_dest *dest)
 	if (cp->protocol != IPPROTO_UDP)
 		conn_flags &= ~IP_VS_CONN_F_ONE_PACKET;
 	flags = cp->flags;
+	svc = rcu_dereference(dest->svc);
+	if (svc && (svc->flags & IP_VS_SVC_F_SECURE_TCP))
+		flags |= IP_VS_CONN_F_SECURE_TCP;
 	/* Bind with the destination and its corresponding transmitter */
 	if (flags & IP_VS_CONN_F_SYNC) {
 		/* Synced conns are hashed, so they can not get this flag */
diff --git a/net/netfilter/ipvs/ip_vs_core.c b/net/netfilter/ipvs/ip_vs_core.c
index ba0957798bad..aa8a3a964ffd 100644
--- a/net/netfilter/ipvs/ip_vs_core.c
+++ b/net/netfilter/ipvs/ip_vs_core.c
@@ -784,6 +784,9 @@ int ip_vs_leave(struct ip_vs_service *svc, struct sk_buff *skb,
 				      IP_VS_CONN_F_ONE_PACKET : 0;
 		union nf_inet_addr daddr = { .all = { 0, 0, 0, 0 } };
 
+		if (svc->flags & IP_VS_SVC_F_SECURE_TCP)
+			flags |= IP_VS_CONN_F_SECURE_TCP;
+
 		/* create a new connection entry */
 		IP_VS_DBG(6, "%s(): create a cache_bypass entry\n", __func__);
 		{
-- 
2.51.0