6.12-stable review patch. If anyone has any objections, please let me know.
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From: Tobias Brunner tobias@strongswan.org
[ Upstream commit e3fd0577768584ece824c8b661c40fb3d912812a ]
This fixes an issue that's caused if there is a mismatch between the data offset in the GRO header and the length fields in the regular sk_buff due to the pskb_pull()/skb_push() calls. That's because the UDP GRO layer stripped off the UDP header via skb_gro_pull() already while the UDP header was explicitly not pulled/pushed in this function.
For example, an IKE packet that triggered this had len=data_len=1268 and the data_offset in the GRO header was 28 (IPv4 + UDP). So pskb_pull() was called with an offset of 28-8=20, which reduced len to 1248 and via pskb_may_pull() and __pskb_pull_tail() it also set data_len to 1248. As the ESP offload module was not loaded, the function bailed out and called skb_push(), which restored len to 1268, however, data_len remained at 1248.
So while skb_headlen() was 0 before, it was now 20. The latter caused a difference of 8 instead of 28 (or 0 if pskb_pull()/skb_push() was called with the complete GRO data_offset) in gro_try_pull_from_frag0() that triggered a call to gro_pull_from_frag0() that corrupted the packet.
This change uses a more GRO-like approach seen in other GRO receivers via skb_gro_header() to just read the actual data we are interested in and does not try to "restore" the UDP header at this point to call the existing function. If the offload module is not loaded, it immediately bails out, otherwise, it only does a quick check to see if the packet is an IKE or keepalive packet instead of calling the existing function.
Fixes: 172bf009c18d ("xfrm: Support GRO for IPv4 ESP in UDP encapsulation") Fixes: 221ddb723d90 ("xfrm: Support GRO for IPv6 ESP in UDP encapsulation") Signed-off-by: Tobias Brunner tobias@strongswan.org Signed-off-by: Steffen Klassert steffen.klassert@secunet.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/ipv4/xfrm4_input.c | 18 ++++++++++-------- net/ipv6/xfrm6_input.c | 18 ++++++++++-------- 2 files changed, 20 insertions(+), 16 deletions(-)
diff --git a/net/ipv4/xfrm4_input.c b/net/ipv4/xfrm4_input.c index a620618cc568a..17d3fc2fab4cc 100644 --- a/net/ipv4/xfrm4_input.c +++ b/net/ipv4/xfrm4_input.c @@ -182,11 +182,15 @@ struct sk_buff *xfrm4_gro_udp_encap_rcv(struct sock *sk, struct list_head *head, int offset = skb_gro_offset(skb); const struct net_offload *ops; struct sk_buff *pp = NULL; - int ret; - - offset = offset - sizeof(struct udphdr); + int len, dlen; + __u8 *udpdata; + __be32 *udpdata32;
- if (!pskb_pull(skb, offset)) + len = skb->len - offset; + dlen = offset + min(len, 8); + udpdata = skb_gro_header(skb, dlen, offset); + udpdata32 = (__be32 *)udpdata; + if (unlikely(!udpdata)) return NULL;
rcu_read_lock(); @@ -194,11 +198,10 @@ struct sk_buff *xfrm4_gro_udp_encap_rcv(struct sock *sk, struct list_head *head, if (!ops || !ops->callbacks.gro_receive) goto out;
- ret = __xfrm4_udp_encap_rcv(sk, skb, false); - if (ret) + /* check if it is a keepalive or IKE packet */ + if (len <= sizeof(struct ip_esp_hdr) || udpdata32[0] == 0) goto out;
- skb_push(skb, offset); NAPI_GRO_CB(skb)->proto = IPPROTO_UDP;
pp = call_gro_receive(ops->callbacks.gro_receive, head, skb); @@ -208,7 +211,6 @@ struct sk_buff *xfrm4_gro_udp_encap_rcv(struct sock *sk, struct list_head *head,
out: rcu_read_unlock(); - skb_push(skb, offset); NAPI_GRO_CB(skb)->same_flow = 0; NAPI_GRO_CB(skb)->flush = 1;
diff --git a/net/ipv6/xfrm6_input.c b/net/ipv6/xfrm6_input.c index 4abc5e9d63227..841c81abaaf4f 100644 --- a/net/ipv6/xfrm6_input.c +++ b/net/ipv6/xfrm6_input.c @@ -179,14 +179,18 @@ struct sk_buff *xfrm6_gro_udp_encap_rcv(struct sock *sk, struct list_head *head, int offset = skb_gro_offset(skb); const struct net_offload *ops; struct sk_buff *pp = NULL; - int ret; + int len, dlen; + __u8 *udpdata; + __be32 *udpdata32;
if (skb->protocol == htons(ETH_P_IP)) return xfrm4_gro_udp_encap_rcv(sk, head, skb);
- offset = offset - sizeof(struct udphdr); - - if (!pskb_pull(skb, offset)) + len = skb->len - offset; + dlen = offset + min(len, 8); + udpdata = skb_gro_header(skb, dlen, offset); + udpdata32 = (__be32 *)udpdata; + if (unlikely(!udpdata)) return NULL;
rcu_read_lock(); @@ -194,11 +198,10 @@ struct sk_buff *xfrm6_gro_udp_encap_rcv(struct sock *sk, struct list_head *head, if (!ops || !ops->callbacks.gro_receive) goto out;
- ret = __xfrm6_udp_encap_rcv(sk, skb, false); - if (ret) + /* check if it is a keepalive or IKE packet */ + if (len <= sizeof(struct ip_esp_hdr) || udpdata32[0] == 0) goto out;
- skb_push(skb, offset); NAPI_GRO_CB(skb)->proto = IPPROTO_UDP;
pp = call_gro_receive(ops->callbacks.gro_receive, head, skb); @@ -208,7 +211,6 @@ struct sk_buff *xfrm6_gro_udp_encap_rcv(struct sock *sk, struct list_head *head,
out: rcu_read_unlock(); - skb_push(skb, offset); NAPI_GRO_CB(skb)->same_flow = 0; NAPI_GRO_CB(skb)->flush = 1;