From: Florian Westphal <fw@xxxxxxxxx>
Once we allow userspace to receive gso/gro packets, userspace
needs to be able to determine when checksums appear to be
broken, but are not.
NFQA_SKB_CSUMNOTREADY means 'checksums will be fixed in kernel
later, pretend they are ok'.
NFQA_SKB_GSO could be used for statistics, or to determine when
packet size exceeds mtu.
Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
---
include/uapi/linux/netfilter/nfnetlink_queue.h | 7 +++++++
net/netfilter/nfnetlink_queue_core.c | 16 ++++++++++++++++
2 files changed, 23 insertions(+)
diff --git a/include/uapi/linux/netfilter/nfnetlink_queue.h b/include/uapi/linux/netfilter/nfnetlink_queue.h
index 70ec8c2..0069da3 100644
--- a/include/uapi/linux/netfilter/nfnetlink_queue.h
+++ b/include/uapi/linux/netfilter/nfnetlink_queue.h
@@ -45,6 +45,7 @@ enum nfqnl_attr_type {
NFQA_CT, /* nf_conntrack_netlink.h */
NFQA_CT_INFO, /* enum ip_conntrack_info */
NFQA_CAP_LEN, /* __u32 length of captured packet */
+ NFQA_SKB_INFO, /* __u32 skb meta information */
__NFQA_MAX
};
@@ -98,4 +99,10 @@ enum nfqnl_attr_config {
#define NFQA_CFG_F_CONNTRACK (1 << 1)
#define NFQA_CFG_F_MAX (1 << 2)
+/* flags for NFQA_SKB_INFO */
+/* packet appears to have wrong checksums, but they are ok */
+#define NFQA_SKB_CSUMNOTREADY (1 << 0)
+/* packet is GSO (i.e., exceeds device mtu) */
+#define NFQA_SKB_GSO (1 << 1)
+
#endif /* _NFNETLINK_QUEUE_H */
diff --git a/net/netfilter/nfnetlink_queue_core.c b/net/netfilter/nfnetlink_queue_core.c
index edbae4c..d052cd6 100644
--- a/net/netfilter/nfnetlink_queue_core.c
+++ b/net/netfilter/nfnetlink_queue_core.c
@@ -272,6 +272,18 @@ nfqnl_zcopy(struct sk_buff *to, const struct sk_buff *from, int len, int hlen)
skb_shinfo(to)->nr_frags = j;
}
+static int nfqnl_put_packet_info(struct sk_buff *nlskb, struct sk_buff *packet)
+{
+ __u32 flags = 0;
+
+ if (packet->ip_summed == CHECKSUM_PARTIAL)
+ flags = NFQA_SKB_CSUMNOTREADY;
+ if (skb_is_gso(packet))
+ flags |= NFQA_SKB_GSO;
+
+ return flags ? nla_put_be32(nlskb, NFQA_SKB_INFO, htonl(flags)) : 0;
+}
+
static struct sk_buff *
nfqnl_build_packet_message(struct nfqnl_instance *queue,
struct nf_queue_entry *entry,
@@ -301,6 +313,7 @@ nfqnl_build_packet_message(struct nfqnl_instance *queue,
#endif
+ nla_total_size(sizeof(u_int32_t)) /* mark */
+ nla_total_size(sizeof(struct nfqnl_msg_packet_hw))
+ + nla_total_size(sizeof(u_int32_t)) /* skbinfo */
+ nla_total_size(sizeof(u_int32_t)); /* cap_len */
if (entskb->tstamp.tv64)
@@ -454,6 +467,9 @@ nfqnl_build_packet_message(struct nfqnl_instance *queue,
if (cap_len > 0 && nla_put_be32(skb, NFQA_CAP_LEN, htonl(cap_len)))
goto nla_put_failure;
+ if (nfqnl_put_packet_info(skb, entskb))
+ goto nla_put_failure;
+
if (data_len) {
struct nlattr *nla;
--
1.7.10.4
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