[PATCH net-next] ipv4: accept u8 in IP_TOS ancillary data

[PATCH net-next] ipv4: accept u8 in IP_TOS ancillary data

[Eric Dumazet]

From: Eric Dumazet <edumazet@google.com>

In commit f02db315b8d8 ("ipv4: IP_TOS and IP_TTL can be specified as
ancillary data") Francesco added IP_TOS values specified as integer.

However, kernel sends to userspace (at recvmsg() time) an IP_TOS value
in a single byte, when IP_RECVTOS is set on the socket.

It can be very useful to reflect all ancillary options as given by the
kernel in a subsequent sendmsg(), instead of aborting the sendmsg() with
EINVAL after Francesco patch.

So this patch extends IP_TOS ancillary to accept an u8, so that an UDP
server can simply reuse same ancillary block without having to mangle
it.

Jesper can then augment
https://github.com/netoptimizer/network-testing/blob/master/src/udp_example02.c
to add TOS reflection ;)

Fixes: f02db315b8d8 ("ipv4: IP_TOS and IP_TTL can be specified as ancillary data")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Francesco Fusco <ffusco@redhat.com> 
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
---
 net/ipv4/ip_sockglue.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index 71a52f4d4cffba2db9353f43dc817689bf4fab10..af4919792b6a812041dcb18ff30aa8b27482c7a2 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -284,9 +284,12 @@ int ip_cmsg_send(struct sock *sk, struct msghdr *msg, struct ipcm_cookie *ipc,
 			ipc->ttl = val;
 			break;
 		case IP_TOS:
-			if (cmsg->cmsg_len != CMSG_LEN(sizeof(int)))
+			if (cmsg->cmsg_len == CMSG_LEN(sizeof(int)))
+				val = *(int *)CMSG_DATA(cmsg);
+			else if (cmsg->cmsg_len == CMSG_LEN(sizeof(u8)))
+				val = *(u8 *)CMSG_DATA(cmsg);
+			else
 				return -EINVAL;
-			val = *(int *)CMSG_DATA(cmsg);
 			if (val < 0 || val > 255)
 				return -EINVAL;
 			ipc->tos = val;

Re: [PATCH net-next] ipv4: accept u8 in IP_TOS ancillary data

[Jesper Dangaard Brouer]

On Wed, 07 Sep 2016 21:52:56 -0700
Eric Dumazet <eric.dumazet@gmail.com> wrote:

> From: Eric Dumazet <edumazet@google.com>
> 
> In commit f02db315b8d8 ("ipv4: IP_TOS and IP_TTL can be specified as
> ancillary data") Francesco added IP_TOS values specified as integer.
> 
> However, kernel sends to userspace (at recvmsg() time) an IP_TOS value
> in a single byte, when IP_RECVTOS is set on the socket.
> 
> It can be very useful to reflect all ancillary options as given by the
> kernel in a subsequent sendmsg(), instead of aborting the sendmsg() with
> EINVAL after Francesco patch.
> 
> So this patch extends IP_TOS ancillary to accept an u8, so that an UDP
> server can simply reuse same ancillary block without having to mangle
> it.
> 
> Jesper can then augment
> https://github.com/netoptimizer/network-testing/blob/master/src/udp_example02.c
> to add TOS reflection ;)

This is actually your old program ;-)
Do I need to change anything, as I'm just bouncing the packet back with sendmsg() ?


> Fixes: f02db315b8d8 ("ipv4: IP_TOS and IP_TTL can be specified as ancillary data")
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Cc: Francesco Fusco <ffusco@redhat.com> 
> Cc: Jesper Dangaard Brouer <brouer@redhat.com>

Looks like a good fix,

Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>

> ---
>  net/ipv4/ip_sockglue.c |    7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
> index 71a52f4d4cffba2db9353f43dc817689bf4fab10..af4919792b6a812041dcb18ff30aa8b27482c7a2 100644
> --- a/net/ipv4/ip_sockglue.c
> +++ b/net/ipv4/ip_sockglue.c
> @@ -284,9 +284,12 @@ int ip_cmsg_send(struct sock *sk, struct msghdr *msg, struct ipcm_cookie *ipc,
>  			ipc->ttl = val;
>  			break;
>  		case IP_TOS:
> -			if (cmsg->cmsg_len != CMSG_LEN(sizeof(int)))
> +			if (cmsg->cmsg_len == CMSG_LEN(sizeof(int)))
> +				val = *(int *)CMSG_DATA(cmsg);
> +			else if (cmsg->cmsg_len == CMSG_LEN(sizeof(u8)))
> +				val = *(u8 *)CMSG_DATA(cmsg);
> +			else
>  				return -EINVAL;
> -			val = *(int *)CMSG_DATA(cmsg);
>  			if (val < 0 || val > 255)
>  				return -EINVAL;
>  			ipc->tos = val;
> 
> 



-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  Author of http://www.iptv-analyzer.org
  LinkedIn: http://www.linkedin.com/in/brouer

Re: [PATCH net-next] ipv4: accept u8 in IP_TOS ancillary data

[Eric Dumazet]

On Thu, 2016-09-08 at 11:15 +0200, Jesper Dangaard Brouer wrote:
> On Wed, 07 Sep 2016 21:52:56 -0700
> Eric Dumazet <eric.dumazet@gmail.com> wrote:
> 
> > From: Eric Dumazet <edumazet@google.com>
> > 
> > In commit f02db315b8d8 ("ipv4: IP_TOS and IP_TTL can be specified as
> > ancillary data") Francesco added IP_TOS values specified as integer.
> > 
> > However, kernel sends to userspace (at recvmsg() time) an IP_TOS value
> > in a single byte, when IP_RECVTOS is set on the socket.
> > 
> > It can be very useful to reflect all ancillary options as given by the
> > kernel in a subsequent sendmsg(), instead of aborting the sendmsg() with
> > EINVAL after Francesco patch.
> > 
> > So this patch extends IP_TOS ancillary to accept an u8, so that an UDP
> > server can simply reuse same ancillary block without having to mangle
> > it.
> > 
> > Jesper can then augment
> > https://github.com/netoptimizer/network-testing/blob/master/src/udp_example02.c
> > to add TOS reflection ;)
> 
> This is actually your old program ;-)
> Do I need to change anything, as I'm just bouncing the packet back with sendmsg() ?

I guess you want to add an option and if this option is requested by the
user, add :

	setsockopt(fd, SOL_IP, IP_PKTINFO, &on, sizeof(on));
+	if (tos_reflect)
+		setsockopt(fd, SOL_IP, IP_RECVTOS, &on, sizeof(on));

before the loop doing the recvmsg()/sendmsg() calls.

Thanks !
 

Re: [PATCH net-next] ipv4: accept u8 in IP_TOS ancillary data

[Jesper Dangaard Brouer]

On Thu, 08 Sep 2016 06:31:14 -0700
Eric Dumazet <eric.dumazet@gmail.com> wrote:

> On Thu, 2016-09-08 at 11:15 +0200, Jesper Dangaard Brouer wrote:
> > On Wed, 07 Sep 2016 21:52:56 -0700
> > Eric Dumazet <eric.dumazet@gmail.com> wrote:
> >   
> > > From: Eric Dumazet <edumazet@google.com>
> > > 
> > > In commit f02db315b8d8 ("ipv4: IP_TOS and IP_TTL can be specified as
> > > ancillary data") Francesco added IP_TOS values specified as integer.
> > > 
> > > However, kernel sends to userspace (at recvmsg() time) an IP_TOS value
> > > in a single byte, when IP_RECVTOS is set on the socket.
> > > 
> > > It can be very useful to reflect all ancillary options as given by the
> > > kernel in a subsequent sendmsg(), instead of aborting the sendmsg() with
> > > EINVAL after Francesco patch.
> > > 
> > > So this patch extends IP_TOS ancillary to accept an u8, so that an UDP
> > > server can simply reuse same ancillary block without having to mangle
> > > it.
> > > 
> > > Jesper can then augment
> > > https://github.com/netoptimizer/network-testing/blob/master/src/udp_example02.c
> > > to add TOS reflection ;)  
> > 
> > This is actually your old program ;-)
> > Do I need to change anything, as I'm just bouncing the packet back with sendmsg() ?  
> 
> I guess you want to add an option and if this option is requested by the
> user, add :
> 
> 	setsockopt(fd, SOL_IP, IP_PKTINFO, &on, sizeof(on));
> +	if (tos_reflect)
> +		setsockopt(fd, SOL_IP, IP_RECVTOS, &on, sizeof(on));
> 
> before the loop doing the recvmsg()/sendmsg() calls.

Hi Eric,

I've implemented what you suggested:
 https://github.com/netoptimizer/network-testing/commit/0758ad77a96ecb1

Now QA can use this tool to verify the kernel commit ;-)

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  Author of http://www.iptv-analyzer.org
  LinkedIn: http://www.linkedin.com/in/brouer

Re: [PATCH net-next] ipv4: accept u8 in IP_TOS ancillary data

[David Miller]

From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Wed, 07 Sep 2016 21:52:56 -0700

> From: Eric Dumazet <edumazet@google.com>
> 
> In commit f02db315b8d8 ("ipv4: IP_TOS and IP_TTL can be specified as
> ancillary data") Francesco added IP_TOS values specified as integer.
> 
> However, kernel sends to userspace (at recvmsg() time) an IP_TOS value
> in a single byte, when IP_RECVTOS is set on the socket.
> 
> It can be very useful to reflect all ancillary options as given by the
> kernel in a subsequent sendmsg(), instead of aborting the sendmsg() with
> EINVAL after Francesco patch.
> 
> So this patch extends IP_TOS ancillary to accept an u8, so that an UDP
> server can simply reuse same ancillary block without having to mangle
> it.
> 
> Jesper can then augment
> https://github.com/netoptimizer/network-testing/blob/master/src/udp_example02.c
> to add TOS reflection ;)
> 
> Fixes: f02db315b8d8 ("ipv4: IP_TOS and IP_TTL can be specified as ancillary data")
> Signed-off-by: Eric Dumazet <edumazet@google.com>

Applied, thanks Eric.