git
/
linux
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

net/ip6_tunnel: Prevent perpetual tunnel growth 

Similarly to ipv4 tunnel, ipv6 version updates dev->needed_headroom, too.
While ipv4 tunnel headroom adjustment growth was limited in
commit 5ae1e9922b ("net: ip_tunnel: prevent perpetual headroom growth"),
ipv6 tunnel yet increases the headroom without any ceiling.

Reflect ipv4 tunnel headroom adjustment limit on ipv6 version.

Credits to Francesco Ruggeri, who was originally debugging this issue
and wrote local Arista-specific patch and a reproducer.

Fixes: 8eb30be035 ("ipv6: Create ip6_tnl_xmit")
Cc: Florian Westphal <fw@strlen.de>
Cc: Francesco Ruggeri <fruggeri05@gmail.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Link: https://patch.msgid.link/20251009-ip6_tunnel-headroom-v2-1-8e4dbd8f7e35@arista.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Dmitry Safonov 2025-10-09 16:02:19 +01:00 committed by Jakub Kicinski
parent e4d0c909bf
commit 21f4d45eba
3 changed files with 16 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
include/net/ip_tunnels.h
View File

@ -611,6 +611,21 @@ struct metadata_dst *iptunnel_metadata_reply(struct metadata_dst *md,
int skb_tunnel_check_pmtu(struct sk_buff *skb, struct dst_entry *encap_dst,
int headroom, bool reply);
static inline void ip_tunnel_adj_headroom(struct net_device *dev,
unsigned int headroom)
{
/* we must cap headroom to some upperlimit, else pskb_expand_head
* will overflow header offsets in skb_headers_offset_update().
*/
const unsigned int max_allowed = 512;
if (headroom > max_allowed)
headroom = max_allowed;
if (headroom > READ_ONCE(dev->needed_headroom))
WRITE_ONCE(dev->needed_headroom, headroom);
}
int iptunnel_handle_offloads(struct sk_buff *skb, int gso_type_mask);
static inline int iptunnel_pull_offloads(struct sk_buff *skb)

14
net/ipv4/ip_tunnel.c
View File

@ -568,20 +568,6 @@ static int tnl_update_pmtu(struct net_device *dev, struct sk_buff *skb,
return 0;
}
static void ip_tunnel_adj_headroom(struct net_device *dev, unsigned int headroom)
{
/* we must cap headroom to some upperlimit, else pskb_expand_head
* will overflow header offsets in skb_headers_offset_update().
*/
static const unsigned int max_allowed = 512;
if (headroom > max_allowed)
headroom = max_allowed;
if (headroom > READ_ONCE(dev->needed_headroom))
WRITE_ONCE(dev->needed_headroom, headroom);
}
void ip_md_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
u8 proto, int tunnel_hlen)
{

3
net/ipv6/ip6_tunnel.c
View File

@ -1257,8 +1257,7 @@ route_lookup:
*/
max_headroom = LL_RESERVED_SPACE(tdev) + sizeof(struct ipv6hdr)
+ dst->header_len + t->hlen;
if (max_headroom > READ_ONCE(dev->needed_headroom))
WRITE_ONCE(dev->needed_headroom, max_headroom);
ip_tunnel_adj_headroom(dev, max_headroom);
err = ip6_tnl_encap(skb, t, &proto, fl6);
if (err)