netfilter: nf_ct_ftp: add sequence tracking pickup facility for injected entries

This patch allows the FTP helper to pickup the sequence tracking from
the first packet seen. This is useful to fix the breakage of the first
FTP command after the failover while using conntrackd to synchronize
states.

The seq_aft_nl_num field in struct nf_ct_ftp_info has been shrinked to
16-bits (enough for what it does), so we can use the remaining 16-bits
to store the flags while using the same size for the private FTP helper
data.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 5 insertions, 1 deletions

diff --git a/include/linux/netfilter/nf_conntrack_ftp.h b/include/linux/netfilter/nf_conntrack_ftp.h
index 28f18df3652..8faf3f792d1 100644
--- a/include/linux/netfilter/nf_conntrack_ftp.h
+++ b/include/linux/netfilter/nf_conntrack_ftp.h
@@ -18,13 +18,17 @@ enum nf_ct_ftp_type {
 
 #define FTP_PORT	21
 
+#define NF_CT_FTP_SEQ_PICKUP	(1 << 0)
+
 #define NUM_SEQ_TO_REMEMBER 2
 /* This structure exists only once per master */
 struct nf_ct_ftp_master {
 	/* Valid seq positions for cmd matching after newline */
 	u_int32_t seq_aft_nl[IP_CT_DIR_MAX][NUM_SEQ_TO_REMEMBER];
 	/* 0 means seq_match_aft_nl not set */
-	int seq_aft_nl_num[IP_CT_DIR_MAX];
+	u_int16_t seq_aft_nl_num[IP_CT_DIR_MAX];
+	/* pickup sequence tracking, useful for conntrackd */
+	u_int16_t flags[IP_CT_DIR_MAX];
 };
 
 struct nf_conntrack_expect;