[PATCH net-next 1/2] net: l3mdev: Add master device lookup by index

[PATCH net-next 1/2] net: l3mdev: Add master device lookup by index

[David Ahern]

Add helper to lookup master index given a device index.

Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
---
 include/net/l3mdev.h | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/include/net/l3mdev.h b/include/net/l3mdev.h
index 774d85b2d5d9..786226f8e77b 100644
--- a/include/net/l3mdev.h
+++ b/include/net/l3mdev.h
@@ -51,6 +51,24 @@ static inline int l3mdev_master_ifindex(struct net_device *dev)
 	return ifindex;
 }
 
+static inline int l3mdev_master_ifindex_by_index(struct net *net, int ifindex)
+{
+	struct net_device *dev;
+	int rc = 0;
+
+	if (likely(ifindex)) {
+		rcu_read_lock();
+
+		dev = dev_get_by_index_rcu(net, ifindex);
+		if (dev)
+			rc = l3mdev_master_ifindex_rcu(dev);
+
+		rcu_read_unlock();
+	}
+
+	return rc;
+}
+
 /* get index of an interface to use for FIB lookups. For devices
  * enslaved to an L3 master device FIB lookups are based on the
  * master index
@@ -167,6 +185,11 @@ static inline int l3mdev_master_ifindex(struct net_device *dev)
 	return 0;
 }
 
+static inline int l3mdev_master_ifindex_by_index(struct net *net, int ifindex)
+{
+	return 0;
+}
+
 static inline int l3mdev_fib_oif_rcu(struct net_device *dev)
 {
 	return dev ? dev->ifindex : 0;
-- 
1.9.1

[PATCH net-next 2/2] net: Add support for vrf-global TCP servers

[David Ahern]

Allow a process to have a "VRF-global" listen socket. In this case the
listen socket is not bound to a VRF device but child sockets derived
from it are bound to the VRF device the original packet was received
on. This avoids the need to replicate services or create additional
listen sockets as VRF devices are created (and the corresponding tear
down as VRFs are deleted).

Processes can learn the VRF association for the child socket using
getsockopt and the SO_BINDTODEVICE option.

Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
---
 net/ipv4/syncookies.c | 6 ++++--
 net/ipv4/tcp_input.c  | 4 +++-
 net/ipv4/tcp_ipv4.c   | 1 +
 net/ipv6/syncookies.c | 7 +++++--
 4 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
index 4cbe9f0a4281..85ff306a5930 100644
--- a/net/ipv4/syncookies.c
+++ b/net/ipv4/syncookies.c
@@ -18,6 +18,7 @@
 #include <linux/export.h>
 #include <net/tcp.h>
 #include <net/route.h>
+#include <net/l3mdev.h>
 
 extern int sysctl_tcp_syncookies;
 
@@ -351,7 +352,8 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
 	treq->snt_synack.v64	= 0;
 	treq->tfo_listener	= false;
 
-	ireq->ir_iif = sk->sk_bound_dev_if;
+	ireq->ir_iif = sk->sk_bound_dev_if ? :
+			l3mdev_master_ifindex_by_index(sock_net(sk), skb->skb_iif);
 
 	/* We throwed the options of the initial SYN away, so we hope
 	 * the ACK carries the same options again (see RFC1122 4.2.3.8)
@@ -371,7 +373,7 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
 	 * hasn't changed since we received the original syn, but I see
 	 * no easy way to do this.
 	 */
-	flowi4_init_output(&fl4, sk->sk_bound_dev_if, ireq->ir_mark,
+	flowi4_init_output(&fl4, ireq->ir_iif, ireq->ir_mark,
 			   RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE, IPPROTO_TCP,
 			   inet_sk_flowi_flags(sk),
 			   opt->srr ? opt->faddr : ireq->ir_rmt_addr,
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index fdd88c3803a6..af884f237332 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -72,6 +72,7 @@
 #include <net/dst.h>
 #include <net/tcp.h>
 #include <net/inet_common.h>
+#include <net/l3mdev.h>
 #include <linux/ipsec.h>
 #include <asm/unaligned.h>
 #include <linux/errqueue.h>
@@ -6187,7 +6188,8 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops,
 	tcp_openreq_init(req, &tmp_opt, skb, sk);
 
 	/* Note: tcp_v6_init_req() might override ir_iif for link locals */
-	inet_rsk(req)->ir_iif = sk->sk_bound_dev_if;
+	inet_rsk(req)->ir_iif = sk->sk_bound_dev_if ? :
+			l3mdev_master_ifindex_by_index(sock_net(sk), skb->skb_iif);
 
 	af_ops->init_req(req, sk, skb);
 
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index ba09016d1bfd..d3a10f9f763b 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1275,6 +1275,7 @@ struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,
 	ireq		      = inet_rsk(req);
 	sk_daddr_set(newsk, ireq->ir_rmt_addr);
 	sk_rcv_saddr_set(newsk, ireq->ir_loc_addr);
+	newsk->sk_bound_dev_if = ireq->ir_iif;
 	newinet->inet_saddr	      = ireq->ir_loc_addr;
 	inet_opt	      = ireq->opt;
 	rcu_assign_pointer(newinet->inet_opt, inet_opt);
diff --git a/net/ipv6/syncookies.c b/net/ipv6/syncookies.c
index bb8f2fa1c7fb..d33bec50c711 100644
--- a/net/ipv6/syncookies.c
+++ b/net/ipv6/syncookies.c
@@ -20,6 +20,7 @@
 #include <linux/kernel.h>
 #include <net/ipv6.h>
 #include <net/tcp.h>
+#include <net/l3mdev.h>
 
 #define COOKIEBITS 24	/* Upper bits store count */
 #define COOKIEMASK (((__u32)1 << COOKIEBITS) - 1)
@@ -193,7 +194,9 @@ struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
 		ireq->pktopts = skb;
 	}
 
-	ireq->ir_iif = sk->sk_bound_dev_if;
+	ireq->ir_iif = sk->sk_bound_dev_if ? :
+		l3mdev_master_ifindex_by_index(sock_net(sk), skb->skb_iif);
+
 	/* So that link locals have meaning */
 	if (!sk->sk_bound_dev_if &&
 	    ipv6_addr_type(&ireq->ir_v6_rmt_addr) & IPV6_ADDR_LINKLOCAL)
@@ -224,7 +227,7 @@ struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
 		fl6.daddr = ireq->ir_v6_rmt_addr;
 		final_p = fl6_update_dst(&fl6, np->opt, &final);
 		fl6.saddr = ireq->ir_v6_loc_addr;
-		fl6.flowi6_oif = sk->sk_bound_dev_if;
+		fl6.flowi6_oif = ireq->ir_iif;
 		fl6.flowi6_mark = ireq->ir_mark;
 		fl6.fl6_dport = ireq->ir_rmt_port;
 		fl6.fl6_sport = inet_sk(sk)->inet_sport;
-- 
1.9.1

Re: [PATCH net-next 1/2] net: l3mdev: Add master device lookup by index

[David Miller]

From: David Ahern <dsa@cumulusnetworks.com>
Date: Thu, 19 Nov 2015 12:32:00 -0800

> Add helper to lookup master index given a device index.
> 
> Signed-off-by: David Ahern <dsa@cumulusnetworks.com>

I don't like where this is going.

sk->sk_bound_dev_if is for device bindings which the user has
explicitly asked for.

We should never, therefore, automatically set it without the user's
consent.

I'm not applying these patches, sorry.

Re: [PATCH net-next 1/2] net: l3mdev: Add master device lookup by index

[David Ahern]

On 11/22/15 10:23 AM, David Miller wrote:
> From: David Ahern <dsa@cumulusnetworks.com>
> Date: Thu, 19 Nov 2015 12:32:00 -0800
>
>> Add helper to lookup master index given a device index.
>>
>> Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
>
> I don't like where this is going.
>
> sk->sk_bound_dev_if is for device bindings which the user has
> explicitly asked for.
>
> We should never, therefore, automatically set it without the user's
> consent.

In this case the user is running a daemon (bgpd) where a single instance 
works across all VRFs. The listen socket is not bound to a device, so 
this does not override what the user ask for. Child sockets are then 
bound to the VRF device the connection originates over, so it narrows 
the scope of accepted connections to a single VRF.

If you look at the change, e.g.,:

     ireq->ir_iif = sk->sk_bound_dev_if ? : 
l3mdev_master_ifindex_by_index(sock_net(sk), skb->skb_iif);

It keeps user requested sk_bound_dev_if if it is set. If not, applies 
the limited scope of a VRF device if the skb originated on a device 
enslaved to a VRF device.

Re: [PATCH net-next 1/2] net: l3mdev: Add master device lookup by index

[David Miller]

From: David Ahern <dsa@cumulusnetworks.com>
Date: Sun, 22 Nov 2015 10:30:32 -0700

> In this case ...

I understand the problem you are trying to solve, but I am saying
you can't use sk_bound_dev_if to use it.

Re: [PATCH net-next 1/2] net: l3mdev: Add master device lookup by index

[David Ahern]

On 11/22/15 11:17 AM, David Miller wrote:
> From: David Ahern <dsa@cumulusnetworks.com>
> Date: Sun, 22 Nov 2015 10:30:32 -0700
>
>> In this case ...
>
> I understand the problem you are trying to solve, but I am saying
> you can't use sk_bound_dev_if to use it.
>

I am confused by that response given that sk_bound_dev_if is one of the 
key principals for the VRF implementation. Applications wanting to 
communicate over interfaces in a VRF have to set sk_bound_dev_if. If 
sk_bound_dev_if is not set by the kernel when the child socket is 
created the TCP handshake will not complete. It is not something that 
can be deferred until after accept.

Re: [PATCH net-next 1/2] net: l3mdev: Add master device lookup by index

[David Miller]

From: David Ahern <dsa@cumulusnetworks.com>
Date: Sun, 22 Nov 2015 21:02:04 -0700

> I am confused by that response given that sk_bound_dev_if is one of
> the key principals for the VRF implementation. Applications wanting to
> communicate over interfaces in a VRF have to set sk_bound_dev_if.

Yes, they have to set it explicitly.

You are setting it for them in response to the connection
creation, and that's what I object to.

Re: [PATCH net-next 1/2] net: l3mdev: Add master device lookup by index

[David Ahern]

On 11/22/15 9:35 PM, David Miller wrote:
> From: David Ahern <dsa@cumulusnetworks.com>
> Date: Sun, 22 Nov 2015 21:02:04 -0700
>
>> I am confused by that response given that sk_bound_dev_if is one of
>> the key principals for the VRF implementation. Applications wanting to
>> communicate over interfaces in a VRF have to set sk_bound_dev_if.
>
> Yes, they have to set it explicitly.
>
> You are setting it for them in response to the connection
> creation, and that's what I object to.
>

The intent is to not require having N-listen sockets/threads/tasks to 
support N-vrfs for scalability reasons. Having a special DEVICE_ANY 
index adds complexity to socket lookups, so I dropped that idea long 
ago. Would guarding this behavior by a sysctl be acceptable?

[PATCH net-next 1/2] net: l3mdev: Add master device lookup by index

[David Ahern]

Add helper to lookup l3mdev master index given a device index.

Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
---
 include/net/l3mdev.h | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/include/net/l3mdev.h b/include/net/l3mdev.h
index 774d85b2d5d9..786226f8e77b 100644
--- a/include/net/l3mdev.h
+++ b/include/net/l3mdev.h
@@ -51,6 +51,24 @@ static inline int l3mdev_master_ifindex(struct net_device *dev)
 	return ifindex;
 }
 
+static inline int l3mdev_master_ifindex_by_index(struct net *net, int ifindex)
+{
+	struct net_device *dev;
+	int rc = 0;
+
+	if (likely(ifindex)) {
+		rcu_read_lock();
+
+		dev = dev_get_by_index_rcu(net, ifindex);
+		if (dev)
+			rc = l3mdev_master_ifindex_rcu(dev);
+
+		rcu_read_unlock();
+	}
+
+	return rc;
+}
+
 /* get index of an interface to use for FIB lookups. For devices
  * enslaved to an L3 master device FIB lookups are based on the
  * master index
@@ -167,6 +185,11 @@ static inline int l3mdev_master_ifindex(struct net_device *dev)
 	return 0;
 }
 
+static inline int l3mdev_master_ifindex_by_index(struct net *net, int ifindex)
+{
+	return 0;
+}
+
 static inline int l3mdev_fib_oif_rcu(struct net_device *dev)
 {
 	return dev ? dev->ifindex : 0;
-- 
1.9.1

[PATCH net-next 1/2] net: l3mdev: Add master device lookup by index

[David Ahern]

Add helper to lookup l3mdev master index given a device index.

Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
---
 include/net/l3mdev.h | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/include/net/l3mdev.h b/include/net/l3mdev.h
index 774d85b2d5d9..786226f8e77b 100644
--- a/include/net/l3mdev.h
+++ b/include/net/l3mdev.h
@@ -51,6 +51,24 @@ static inline int l3mdev_master_ifindex(struct net_device *dev)
 	return ifindex;
 }
 
+static inline int l3mdev_master_ifindex_by_index(struct net *net, int ifindex)
+{
+	struct net_device *dev;
+	int rc = 0;
+
+	if (likely(ifindex)) {
+		rcu_read_lock();
+
+		dev = dev_get_by_index_rcu(net, ifindex);
+		if (dev)
+			rc = l3mdev_master_ifindex_rcu(dev);
+
+		rcu_read_unlock();
+	}
+
+	return rc;
+}
+
 /* get index of an interface to use for FIB lookups. For devices
  * enslaved to an L3 master device FIB lookups are based on the
  * master index
@@ -167,6 +185,11 @@ static inline int l3mdev_master_ifindex(struct net_device *dev)
 	return 0;
 }
 
+static inline int l3mdev_master_ifindex_by_index(struct net *net, int ifindex)
+{
+	return 0;
+}
+
 static inline int l3mdev_fib_oif_rcu(struct net_device *dev)
 {
 	return dev ? dev->ifindex : 0;
-- 
1.9.1