diff options
| author | Zihan Xi <zihanx@nebusec.ai> | 2026-09-24 05:15:21 +0000 |
|---|---|---|
| committer | Paolo Abeni <pabeni@redhat.com> | 2026-09-29 12:02:37 +0200 |
| commit | 006c8b834aed8b02bd8fb9fb05e9e7ead37d1763 (patch) | |
| tree | c0deb128cd6ead09e9426cda4cc4a7836c608fa5 /include/net | |
| parent | 0f17d2e3dd9cda3ee6d94033d5e5489af168920d (diff) | |
net: gso: limit recursive IP-in-IP segmentation
IP-in-IP GSO can re-enter inet_gso_segment() or ipv6_gso_segment()
for each nested IP header. encap_level tracks header bytes, not callback
depth, so a deep chain can exhaust the kernel stack. Making
inet_gso_segment() stackable introduced unbounded IPv4 nesting; IPIP
GSO/TSO later made the path reachable. The IPv6 stackable path was
introduced separately and uses the same guard.
Count IPv4 and IPv6 GSO handler entries in skb_gso_cb, initialized once
per top-level GSO operation and preserved across GRE/UDP context changes.
Use the existing IP_TUNNEL_RECURSION_LIMIT for both handlers. The first
five entries pass, and the sixth returns -EINVAL before dispatching
another GSO callback.
Fixes: 3347c9602955 ("ipv4: gso: make inet_gso_segment() stackable")
Cc: stable@vger.kernel.org
Reported-by: Vega <vega@nebusec.ai>
Closes: https://lore.kernel.org/all/cover.1790157745.git.zihanx@nebusec.ai/
Assisted-by: LLM
Co-developed-by: Luxing Yin <root@tr0jan.top>
Signed-off-by: Luxing Yin <root@tr0jan.top>
Signed-off-by: Zihan Xi <zihanx@nebusec.ai>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20260924051521.32568-2-zihanx@nebusec.ai
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Diffstat (limited to 'include/net')
| -rw-r--r-- | include/net/gso.h | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/include/net/gso.h b/include/net/gso.h index 29975440cad5..0749230d414e 100644 --- a/include/net/gso.h +++ b/include/net/gso.h @@ -19,10 +19,18 @@ struct skb_gso_cb { int encap_level; __wsum csum; __u16 csum_start; + /* Number of IPv4/IPv6 GSO handler entries for this packet. */ + u8 recursion_counter; }; #define SKB_GSO_CB_OFFSET 32 #define SKB_GSO_CB(skb) ((struct skb_gso_cb *)((skb)->cb + SKB_GSO_CB_OFFSET)) +static inline bool gso_recursion_inc_test(struct sk_buff *skb, + unsigned int limit) +{ + return ++SKB_GSO_CB(skb)->recursion_counter > limit; +} + static inline int skb_tnl_header_len(const struct sk_buff *inner_skb) { return (skb_mac_header(inner_skb) - inner_skb->head) - |