xfrm: pass struct net to xfrm_decode_session wrappers

Preparation patch, extra arg is not used.
No functional changes intended.

This is needed to replace the xfrm session decode functions with
the flow dissector.

skb_flow_dissect() cannot be used as-is, because it attempts to deduce the
'struct net' to use for bpf program fetch from skb->sk or skb->dev, but
xfrm code path can see skbs that have neither sk or dev filled in.

So either flow dissector needs to try harder, e.g. by also trying
skb->dst->dev, or we have to pass the struct net explicitly.

Passing the struct net doesn't look too bad to me, most places
already have it available or can derive it from the output device.
Reported-by: kernel test robot <oliver.sang@intel.com>
Link: https://lore.kernel.org/netdev/202309271628.27fd2187-oliver.sang@intel.com/Signed-off-by: Florian Westphal <fw@strlen.de>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

include/net/xfrm.h

@@ -1207,20 +1207,20 @@ static inline int xfrm6_policy_check_reverse(struct sock *sk, int dir,
 	return __xfrm_policy_check2(sk, dir, skb, AF_INET6, 1);
 }
 
-int __xfrm_decode_session(struct sk_buff *skb, struct flowi *fl,
+int __xfrm_decode_session(struct net *net, struct sk_buff *skb, struct flowi *fl,
 			  unsigned int family, int reverse);
 
-static inline int xfrm_decode_session(struct sk_buff *skb, struct flowi *fl,
+static inline int xfrm_decode_session(struct net *net, struct sk_buff *skb, struct flowi *fl,
 				      unsigned int family)
 {
-	return __xfrm_decode_session(skb, fl, family, 0);
+	return __xfrm_decode_session(net, skb, fl, family, 0);
 }
 
-static inline int xfrm_decode_session_reverse(struct sk_buff *skb,
+static inline int xfrm_decode_session_reverse(struct net *net, struct sk_buff *skb,
 					      struct flowi *fl,
 					      unsigned int family)
 {
-	return __xfrm_decode_session(skb, fl, family, 1);
+	return __xfrm_decode_session(net, skb, fl, family, 1);
 }
 
 int __xfrm_route_forward(struct sk_buff *skb, unsigned short family);
@@ -1296,7 +1296,7 @@ static inline int xfrm_policy_check(struct sock *sk, int dir, struct sk_buff *sk
 {
 	return 1;
 }
-static inline int xfrm_decode_session_reverse(struct sk_buff *skb,
+static inline int xfrm_decode_session_reverse(struct net *net, struct sk_buff *skb,
 					      struct flowi *fl,
 					      unsigned int family)
 {

net/ipv4/icmp.c

@@ -517,7 +517,7 @@ static struct rtable *icmp_route_lookup(struct net *net,
 	} else
 		return rt;
 
-	err = xfrm_decode_session_reverse(skb_in, flowi4_to_flowi(&fl4_dec), AF_INET);
+	err = xfrm_decode_session_reverse(net, skb_in, flowi4_to_flowi(&fl4_dec), AF_INET);
 	if (err)
 		goto relookup_failed;
 

net/ipv4/ip_vti.c

@@ -288,11 +288,11 @@ static netdev_tx_t vti_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
 	switch (skb->protocol) {
 	case htons(ETH_P_IP):
 		memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
-		xfrm_decode_session(skb, &fl, AF_INET);
+		xfrm_decode_session(dev_net(dev), skb, &fl, AF_INET);
 		break;
 	case htons(ETH_P_IPV6):
 		memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
-		xfrm_decode_session(skb, &fl, AF_INET6);
+		xfrm_decode_session(dev_net(dev), skb, &fl, AF_INET6);
 		break;
 	default:
 		goto tx_err;

net/ipv4/netfilter.c

@@ -62,7 +62,7 @@ int ip_route_me_harder(struct net *net, struct sock *sk, struct sk_buff *skb, un
 
 #ifdef CONFIG_XFRM
 	if (!(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) &&
-	    xfrm_decode_session(skb, flowi4_to_flowi(&fl4), AF_INET) == 0) {
+	    xfrm_decode_session(net, skb, flowi4_to_flowi(&fl4), AF_INET) == 0) {
 		struct dst_entry *dst = skb_dst(skb);
 		skb_dst_set(skb, NULL);
 		dst = xfrm_lookup(net, dst, flowi4_to_flowi(&fl4), sk, 0);

net/ipv6/icmp.c

@@ -385,7 +385,7 @@ static struct dst_entry *icmpv6_route_lookup(struct net *net,
 			return dst;
 	}
 
-	err = xfrm_decode_session_reverse(skb, flowi6_to_flowi(&fl2), AF_INET6);
+	err = xfrm_decode_session_reverse(net, skb, flowi6_to_flowi(&fl2), AF_INET6);
 	if (err)
 		goto relookup_failed;
 

net/ipv6/ip6_vti.c

@@ -569,11 +569,11 @@ vti6_tnl_xmit(struct sk_buff *skb, struct net_device *dev)
 			goto tx_err;
 
 		memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
-		xfrm_decode_session(skb, &fl, AF_INET6);
+		xfrm_decode_session(dev_net(dev), skb, &fl, AF_INET6);
 		break;
 	case htons(ETH_P_IP):
 		memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
-		xfrm_decode_session(skb, &fl, AF_INET);
+		xfrm_decode_session(dev_net(dev), skb, &fl, AF_INET);
 		break;
 	default:
 		goto tx_err;

net/ipv6/netfilter.c

@@ -61,7 +61,7 @@ int ip6_route_me_harder(struct net *net, struct sock *sk_partial, struct sk_buff
 
 #ifdef CONFIG_XFRM
 	if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
-	    xfrm_decode_session(skb, flowi6_to_flowi(&fl6), AF_INET6) == 0) {
+	    xfrm_decode_session(net, skb, flowi6_to_flowi(&fl6), AF_INET6) == 0) {
 		skb_dst_set(skb, NULL);
 		dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), sk, 0);
 		if (IS_ERR(dst))

net/netfilter/nf_nat_proto.c

@@ -668,7 +668,7 @@ static int nf_xfrm_me_harder(struct net *net, struct sk_buff *skb, unsigned int
 	struct flowi fl;
 	int err;
 
-	err = xfrm_decode_session(skb, &fl, family);
+	err = xfrm_decode_session(net, skb, &fl, family);
 	if (err < 0)
 		return err;
 

net/xfrm/xfrm_interface_core.c

@@ -538,7 +538,7 @@ static netdev_tx_t xfrmi_xmit(struct sk_buff *skb, struct net_device *dev)
 	switch (skb->protocol) {
 	case htons(ETH_P_IPV6):
 		memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
-		xfrm_decode_session(skb, &fl, AF_INET6);
+		xfrm_decode_session(dev_net(dev), skb, &fl, AF_INET6);
 		if (!dst) {
 			fl.u.ip6.flowi6_oif = dev->ifindex;
 			fl.u.ip6.flowi6_flags |= FLOWI_FLAG_ANYSRC;
@@ -553,7 +553,7 @@ static netdev_tx_t xfrmi_xmit(struct sk_buff *skb, struct net_device *dev)
 		break;
 	case htons(ETH_P_IP):
 		memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
-		xfrm_decode_session(skb, &fl, AF_INET);
+		xfrm_decode_session(dev_net(dev), skb, &fl, AF_INET);
 		if (!dst) {
 			struct rtable *rt;
 

net/xfrm/xfrm_policy.c

@@ -2853,7 +2853,7 @@ static void xfrm_policy_queue_process(struct timer_list *t)
 	/* Fixup the mark to support VTI. */
 	skb_mark = skb->mark;
 	skb->mark = pol->mark.v;
-	xfrm_decode_session(skb, &fl, dst->ops->family);
+	xfrm_decode_session(net, skb, &fl, dst->ops->family);
 	skb->mark = skb_mark;
 	spin_unlock(&pq->hold_queue.lock);
 
@@ -2889,7 +2889,7 @@ static void xfrm_policy_queue_process(struct timer_list *t)
 		/* Fixup the mark to support VTI. */
 		skb_mark = skb->mark;
 		skb->mark = pol->mark.v;
-		xfrm_decode_session(skb, &fl, skb_dst(skb)->ops->family);
+		xfrm_decode_session(net, skb, &fl, skb_dst(skb)->ops->family);
 		skb->mark = skb_mark;
 
 		dst_hold(xfrm_dst_path(skb_dst(skb)));
@@ -3554,7 +3554,7 @@ decode_session6(struct sk_buff *skb, struct flowi *fl, bool reverse)
 }
 #endif
 
-int __xfrm_decode_session(struct sk_buff *skb, struct flowi *fl,
+int __xfrm_decode_session(struct net *net, struct sk_buff *skb, struct flowi *fl,
 			  unsigned int family, int reverse)
 {
 	switch (family) {
@@ -3618,7 +3618,7 @@ int __xfrm_policy_check(struct sock *sk, int dir, struct sk_buff *skb,
 	reverse = dir & ~XFRM_POLICY_MASK;
 	dir &= XFRM_POLICY_MASK;
 
-	if (__xfrm_decode_session(skb, &fl, family, reverse) < 0) {
+	if (__xfrm_decode_session(net, skb, &fl, family, reverse) < 0) {
 		XFRM_INC_STATS(net, LINUX_MIB_XFRMINHDRERROR);
 		return 0;
 	}
@@ -3774,7 +3774,7 @@ int __xfrm_route_forward(struct sk_buff *skb, unsigned short family)
 	struct dst_entry *dst;
 	int res = 1;
 
-	if (xfrm_decode_session(skb, &fl, family) < 0) {
+	if (xfrm_decode_session(net, skb, &fl, family) < 0) {
 		XFRM_INC_STATS(net, LINUX_MIB_XFRMFWDHDRERROR);
 		return 0;
 	}