netdev - [PATCH ipsec-next 1/7] net: xfrm: Don't check for TUNNEL

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Message-Id: <20171220170607.41516-2-lorenzo@google.com>
Date:   Thu, 21 Dec 2017 02:06:01 +0900
From:   Lorenzo Colitti <lorenzo@...gle.com>
To:     netdev@...r.kernel.org
Cc:     steffen.klassert@...unet.com, subashab@...eaurora.org,
        nharold@...gle.com, davem@...emloft.net,
        Lorenzo Colitti <lorenzo@...gle.com>
Subject: [PATCH ipsec-next 1/7] net: xfrm: Don't check for TUNNEL_KEY when hashing VTI tunnels.

Currently, ip_bucket sets the lookup i_key to 0 if the tunnel's
i_flags have VTI_ISVTI flag set but not TUNNEL_KEY. However, it
can can never happen that TUNNEL_KEY is set if VTI_ISVTI is also
set (see below). Therefore, just drop the check for TUNNEL_KEY
and only set i_key to 0 on VTI_ISVTI.

This will allow the VTI code to set TUNNEL_KEY on certain
tunnels in a future change.

None of the callers of ip_bucket pass in TUNNEL_KEY | VTI_ISVTI.
The call graph is as follows:

- ip_tunnel_add
  - ip_tunnel_create
    - ip_tunnel_ioctl
      - ipgre_tunnel_ioctl: can set TUNNEL_KEY but not VTI_ISVTI
      - ipip_tunnel_ioctl: hardcodes i_flags to 0
      - vti_tunnel_ioctl: hardcodes i_flags to VTI_ISVTI
  - ip_tunnel_update: doesn't touch i_flags
  - ip_tunnel_init_net: memsets flags to 0
  - ip_tunnel_newlink
    - ipgre_newlink
      - ipgre_netlink_parms: can set TUNNEL_KEY but not VTI_ISVTI
    - vti_newlink: hardcodes i_flags to VTI_ISVTI
  - ip_tunnel_changelink: doesn't set flags
- ip_tunnel_find
  - ip_tunnel_ioctl (see above)
  - ip_tunnel_newlink (see above)
  - ip_tunnel_changelink (see above)

VTI_ISVTI has the same value as TUNNEL_DONT_FRAGMENT, but that
is never set into tunnel parameters.

Signed-off-by: Lorenzo Colitti <lorenzo@...gle.com>
---
 net/ipv4/ip_tunnel.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
index 5ddb1cb52b..539c8f22c4 100644
--- a/net/ipv4/ip_tunnel.c
+++ b/net/ipv4/ip_tunnel.c
@@ -198,7 +198,7 @@ static struct hlist_head *ip_bucket(struct ip_tunnel_net *itn,
 	else
 		remote = 0;
 
-	if (!(parms->i_flags & TUNNEL_KEY) && (parms->i_flags & VTI_ISVTI))
+	if (parms->i_flags & VTI_ISVTI)
 		i_key = 0;
 
 	h = ip_tunnel_hash(i_key, remote);
-- 
2.15.1.620.gb9897f4670-goog