Re: [PATCH] ipvs: avoid oops in nf_ct_seqadj_set when called from ip_vs_ftp helper

[Julian Anastasov <ja@xxxxxx>]

        Hello,

On Fri, 13 Dec 2013, Jesper Dangaard Brouer wrote:

> The IPVS FTP helper ip_vs_ftp can trigger an OOPS in nf_ct_seqadj_set,
> after commit 41d73ec053d2 (netfilter: nf_conntrack: make sequence
> number adjustments usuable without NAT).
> 
> We can avoid the oops in nf_ct_seqadj_set() by in ip_vs_ftp_out()
> instead of calling nf_nat_mangle_tcp_packet() we simply call
> __nf_nat_mangle_tcp_packet() with a "false" last parameter, which
> indicate not invoking the seqadj code.
> 
> After this fix, I've tested that FTP over IPVS, with module ip_vs_ftp
> loaded, works for both passive and active FTP.
> 
> Fixes: 41d73ec053d2 (netfilter: nf_conntrack: make sequence number 
> adjustments usuable without NAT)
> Signed-off-by: Jesper Dangaard Brouer <brouer@xxxxxxxxxx>
> 
> ---
> I'm uncertain if this is the correct fix.  Perhaps the ip_vs_ftp
> helper need to allocate/init the seqadj extension instead?

        I hope I'll save you some time... What do you
think about such change:

[PATCH net] ipvs: use the new seqadj interface from ip_vs_ftp

diff --git a/net/netfilter/ipvs/ip_vs_ftp.c b/net/netfilter/ipvs/ip_vs_ftp.c
index 77c1732..9c2074d 100644
--- a/net/netfilter/ipvs/ip_vs_ftp.c
+++ b/net/netfilter/ipvs/ip_vs_ftp.c
@@ -34,6 +34,7 @@
 #include <linux/netfilter.h>
 #include <net/netfilter/nf_conntrack.h>
 #include <net/netfilter/nf_conntrack_expect.h>
+#include <net/netfilter/nf_conntrack_seqadj.h>
 #include <net/netfilter/nf_nat.h>
 #include <net/netfilter/nf_nat_helper.h>
 #include <linux/gfp.h>
@@ -260,7 +261,8 @@ static int ip_vs_ftp_out(struct ip_vs_app *app, struct 
ip_vs_conn *cp,
                buf_len = strlen(buf);
 
                ct = nf_ct_get(skb, &ctinfo);
-               if (ct && !nf_ct_is_untracked(ct) && nfct_nat(ct)) {
+               if (ct && !nf_ct_is_untracked(ct) && nfct_nat(ct) &&
+                   nfct_seqadj(ct)) {
                        /* If mangling fails this function will return 0
                         * which will cause the packet to be dropped.
                         * Mangling can only fail under memory pressure,
diff --git a/net/netfilter/ipvs/ip_vs_nfct.c b/net/netfilter/ipvs/ip_vs_nfct.c
index c8beafd..5a355a4 100644
--- a/net/netfilter/ipvs/ip_vs_nfct.c
+++ b/net/netfilter/ipvs/ip_vs_nfct.c
@@ -63,6 +63,7 @@
 #include <net/ip_vs.h>
 #include <net/netfilter/nf_conntrack_core.h>
 #include <net/netfilter/nf_conntrack_expect.h>
+#include <net/netfilter/nf_conntrack_seqadj.h>
 #include <net/netfilter/nf_conntrack_helper.h>
 #include <net/netfilter/nf_conntrack_zones.h>
 
@@ -97,6 +98,11 @@ ip_vs_update_conntrack(struct sk_buff *skb, struct 
ip_vs_conn *cp, int outin)
        if (CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL)
                return;
 
+       /* Applications may adjust TCP seqs */
+       if (cp->app && nf_ct_protonum(ct) == IPPROTO_TCP &&
+           !nfct_seqadj(ct) && !nfct_seqadj_ext_add(ct))
+               return;
+
        /*
         * The connection is not yet in the hashtable, so we update it.
         * CIP->VIP will remain the same, so leave the tuple in
-- 
1.8.4.2

Regards

--
Julian Anastasov <ja@xxxxxx>
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