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authorPablo Neira Ayuso <pablo@netfilter.org>2012-09-21 16:52:08 +0200
committerPablo Neira Ayuso <pablo@netfilter.org>2012-09-24 14:29:40 +0200
commit7be54ca4764bdead40bee7b645a72718c20ff2c8 (patch)
treeda27254d7fe7dd96555668d5369a0e2dcc9bc769
parent54eb3df3a7d01b6cd395bdc1098280f2f93fbec5 (diff)
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>
-rw-r--r--include/linux/netfilter/nf_conntrack_ftp.h6
-rw-r--r--net/netfilter/nf_conntrack_ftp.c21
-rw-r--r--net/netfilter/nf_conntrack_netlink.c4
-rw-r--r--net/netfilter/nfnetlink_cthelper.c3
4 files changed, 31 insertions, 3 deletions
diff --git a/include/linux/netfilter/nf_conntrack_ftp.h b/include/linux/netfilter/nf_conntrack_ftp.h
index 28f18df36525..8faf3f792d13 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;
diff --git a/net/netfilter/nf_conntrack_ftp.c b/net/netfilter/nf_conntrack_ftp.c
index f8cc26ad4456..1ce3befb7c8a 100644
--- a/net/netfilter/nf_conntrack_ftp.c
+++ b/net/netfilter/nf_conntrack_ftp.c
@@ -396,6 +396,12 @@ static int help(struct sk_buff *skb,
/* Look up to see if we're just after a \n. */
if (!find_nl_seq(ntohl(th->seq), ct_ftp_info, dir)) {
+ /* We're picking up this, clear flags and let it continue */
+ if (unlikely(ct_ftp_info->flags[dir] & NF_CT_FTP_SEQ_PICKUP)) {
+ ct_ftp_info->flags[dir] ^= NF_CT_FTP_SEQ_PICKUP;
+ goto skip_nl_seq;
+ }
+
/* Now if this ends in \n, update ftp info. */
pr_debug("nf_conntrack_ftp: wrong seq pos %s(%u) or %s(%u)\n",
ct_ftp_info->seq_aft_nl_num[dir] > 0 ? "" : "(UNSET)",
@@ -406,6 +412,7 @@ static int help(struct sk_buff *skb,
goto out_update_nl;
}
+skip_nl_seq:
/* Initialize IP/IPv6 addr to expected address (it's not mentioned
in EPSV responses) */
cmd.l3num = nf_ct_l3num(ct);
@@ -512,6 +519,19 @@ out_update_nl:
return ret;
}
+static int nf_ct_ftp_from_nlattr(struct nlattr *attr, struct nf_conn *ct)
+{
+ struct nf_ct_ftp_master *ftp = nfct_help_data(ct);
+
+ /* This conntrack has been injected from user-space, always pick up
+ * sequence tracking. Otherwise, the first FTP command after the
+ * failover breaks.
+ */
+ ftp->flags[IP_CT_DIR_ORIGINAL] |= NF_CT_FTP_SEQ_PICKUP;
+ ftp->flags[IP_CT_DIR_REPLY] |= NF_CT_FTP_SEQ_PICKUP;
+ return 0;
+}
+
static struct nf_conntrack_helper ftp[MAX_PORTS][2] __read_mostly;
static const struct nf_conntrack_expect_policy ftp_exp_policy = {
@@ -561,6 +581,7 @@ static int __init nf_conntrack_ftp_init(void)
ftp[i][j].expect_policy = &ftp_exp_policy;
ftp[i][j].me = THIS_MODULE;
ftp[i][j].help = help;
+ ftp[i][j].from_nlattr = nf_ct_ftp_from_nlattr;
if (ports[i] == FTP_PORT)
sprintf(ftp[i][j].name, "ftp");
else
diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index 2dcd080b8c4f..7bbfb3deea30 100644
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -1238,7 +1238,7 @@ ctnetlink_change_helper(struct nf_conn *ct, const struct nlattr * const cda[])
if (help) {
if (help->helper == helper) {
/* update private helper data if allowed. */
- if (helper->from_nlattr && helpinfo)
+ if (helper->from_nlattr)
helper->from_nlattr(helpinfo, ct);
return 0;
} else
@@ -1467,7 +1467,7 @@ ctnetlink_create_conntrack(struct net *net, u16 zone,
goto err2;
}
/* set private helper data if allowed. */
- if (helper->from_nlattr && helpinfo)
+ if (helper->from_nlattr)
helper->from_nlattr(helpinfo, ct);
/* not in hash table yet so not strictly necessary */
diff --git a/net/netfilter/nfnetlink_cthelper.c b/net/netfilter/nfnetlink_cthelper.c
index 3678073360a3..945950a8b1f1 100644
--- a/net/netfilter/nfnetlink_cthelper.c
+++ b/net/netfilter/nfnetlink_cthelper.c
@@ -85,6 +85,9 @@ nfnl_cthelper_from_nlattr(struct nlattr *attr, struct nf_conn *ct)
{
const struct nf_conn_help *help = nfct_help(ct);
+ if (attr == NULL)
+ return -EINVAL;
+
if (help->helper->data_len == 0)
return -EINVAL;