netdev - RE: [PATCH v2 net-next 1/3] ipv6: Prevent unexpected sk->sk

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Date:   Wed, 23 Aug 2017 07:49:09 +0000
From:   Ilya Lesokhin <ilyal@...lanox.com>
To:     Eric Dumazet <eric.dumazet@...il.com>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "davejwatson@...com" <davejwatson@...com>,
        "Aviad Yehezkel" <aviadye@...lanox.com>,
        Boris Pismenny <borisp@...lanox.com>
Subject: RE: [PATCH v2 net-next 1/3] ipv6: Prevent unexpected sk->sk_prot
 changes

> -----Original Message-----
> From: Eric Dumazet [mailto:eric.dumazet@...il.com]
> Sent: Tuesday, August 15, 2017 5:46 PM
> To: Boris Pismenny <borisp@...lanox.com>
> Cc: Ilya Lesokhin <ilyal@...lanox.com>; netdev@...r.kernel.org;
> davem@...emloft.net; davejwatson@...com; Aviad Yehezkel
> <aviadye@...lanox.com>
> Subject: Re: [PATCH v2 net-next 1/3] ipv6: Prevent unexpected sk->sk_prot
> changes
> 
> I am just saying IPV6_ADDRFORM is becoming spaghetti code, and maybe
> this is time to make it modular. 
> 

Hi Eric,
I understand your concern, but I would like to postpone implementing this
feature until the ulp infrastructure stabilizes.
I don't even know how many users want to use IPV6_ADDRFORM on sockets with ulp.
I think that simply returning an error for ulp sockets in the meantime is a reasonable 
compromise.

what do you think about the patch below?

Subject: [PATCH 1/1] ipv6: Disable IPV6_ADDRFORM on sockets with ulp attached

The IPV6_ADDRFORM setsockopt works by overriding sk->sk_prot.
The current KTLS ulp also overrides sk->sk_prot.
Consequently, using IPV6_ADDRFORM when there is a ulp attached is
unsafe and this patch disables it.

Fixes: 3c4d7559159b ('tls: kernel TLS support')
Signed-off-by: Ilya Lesokhin <ilyal@...lanox.com>
---
 net/ipv6/ipv6_sockglue.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c
index 02d795f..d935948 100644
--- a/net/ipv6/ipv6_sockglue.c
+++ b/net/ipv6/ipv6_sockglue.c
@@ -185,8 +185,12 @@ static int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
 					retv = -EBUSY;
 					break;
 				}
-			} else if (sk->sk_protocol != IPPROTO_TCP)
+			} else if (sk->sk_protocol == IPPROTO_TCP) {
+				if (inet_csk(sk)->icsk_ulp_ops)
+					break;
+			} else {
 				break;
+			}
 
 			if (sk->sk_state != TCP_ESTABLISHED) {
 				retv = -ENOTCONN;


Thanks,
Ilya