[GIT PULL v2 0/4] IPVS Fixes for v4.5

Hi Pablo,

please consider these IPVS fixes for v4.5 or
if it is too late please consider them for v4.6.

* Arnd Bergman has corrected an error whereby the SIP persistence engine
  may incorrectly access protocol fields
* Julian Anastasov has corrected a problem reported by Jiri Bohac with the
  connection rescheduling mechanism added in 3.10 when new SYNs in
  connection to dead real server can be redirected to another real server.
* Marco Angaroni resolved a problem in the SIP persistence engine
  whereby the Call-ID could not be found if it was at the beginning of a
  SIP message.

The following changes since commit 017b1b6d28c479f1ad9a7a41f775545a3e1cba35:

  netfilter: nfnetlink_acct: validate NFACCT_FILTER parameters (2016-02-29 13:27:21 +0100)

are available in the git repository at:

  https://git.kernel.org/pub/scm/linux/kernel/git/horms/ipvs.git tags/ipvs-fixes-for-v4.5

for you to fetch changes up to 7617a24f83b5d67f4dab1844956be1cebc44aec8:

  ipvs: correct initial offset of Call-ID header search in SIP persistence engine (2016-03-07 11:53:35 +0900)

----------------------------------------------------------------
Arnd Bergmann (1):
      ipvs: handle ip_vs_fill_iph_skb_off failure

Julian Anastasov (2):
      ipvs: drop first packet to redirect conntrack
      ipvs: allow rescheduling after RST

Marco Angaroni (1):
      ipvs: correct initial offset of Call-ID header search in SIP persistence engine

 include/net/ip_vs.h               | 17 +++++++++++++++++
 net/netfilter/ipvs/ip_vs_core.c   | 38 +++++++++++++++++++++++++++++---------
 net/netfilter/ipvs/ip_vs_pe_sip.c |  6 +++---
 3 files changed, 49 insertions(+), 12 deletions(-)

From: Arnd Bergmann <arnd@arndb.de>

ip_vs_fill_iph_skb_off() may not find an IP header, and gcc has
determined that ip_vs_sip_fill_param() then incorrectly accesses
the protocol fields:

net/netfilter/ipvs/ip_vs_pe_sip.c: In function 'ip_vs_sip_fill_param':
net/netfilter/ipvs/ip_vs_pe_sip.c:76:5: error: 'iph.protocol' may be used uninitialized in this function [-Werror=maybe-uninitialized]
  if (iph.protocol != IPPROTO_UDP)
     ^
net/netfilter/ipvs/ip_vs_pe_sip.c:81:10: error: 'iph.len' may be used uninitialized in this function [-Werror=maybe-uninitialized]
  dataoff = iph.len + sizeof(struct udphdr);
          ^

This adds a check for the ip_vs_fill_iph_skb_off() return code
before looking at the ip header data returned from it.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: b0e010c527de ("ipvs: replace ip_vs_fill_ip4hdr with ip_vs_fill_iph_skb_off")
Acked-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Simon Horman <horms@verge.net.au>
---
 net/netfilter/ipvs/ip_vs_pe_sip.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/netfilter/ipvs/ip_vs_pe_sip.c b/net/netfilter/ipvs/ip_vs_pe_sip.c
index 1b8d594e493a..c4e9ca016a88 100644
--- a/net/netfilter/ipvs/ip_vs_pe_sip.c
+++ b/net/netfilter/ipvs/ip_vs_pe_sip.c

@@ -70,10 +70,10 @@ ip_vs_sip_fill_param(struct ip_vs_conn_param *p, struct sk_buff *skb)
 	const char *dptr;
 	int retc;
 
-	ip_vs_fill_iph_skb(p->af, skb, false, &iph);
+	retc = ip_vs_fill_iph_skb(p->af, skb, false, &iph);
 
 	/* Only useful with UDP */
-	if (iph.protocol != IPPROTO_UDP)
+	if (!retc || iph.protocol != IPPROTO_UDP)
 		return -EINVAL;
 	/* todo: IPv6 fragments:
 	 *       I think this only should be done for the first fragment. /HS

-- 
2.1.4

From: Julian Anastasov <ja@ssi.bg>

Jiri Bohac is reporting for a problem where the attempt
to reschedule existing connection to another real server
needs proper redirect for the conntrack used by the IPVS
connection. For example, when IPVS connection is created
to NAT-ed real server we alter the reply direction of
conntrack. If we later decide to select different real
server we can not alter again the conntrack. And if we
expire the old connection, the new connection is left
without conntrack.

So, the only way to redirect both the IPVS connection and
the Netfilter's conntrack is to drop the SYN packet that
hits existing connection, to wait for the next jiffie
to expire the old connection and its conntrack and to rely
on client's retransmission to create new connection as
usually.

Jiri Bohac provided a fix that drops all SYNs on rescheduling,
I extended his patch to do such drops only for connections
that use conntrack. Here is the original report from Jiri Bohac:

Since commit dc7b3eb900aa ("ipvs: Fix reuse connection if real server
is dead"), new connections to dead servers are redistributed
immediately to new servers.  The old connection is expired using
ip_vs_conn_expire_now() which sets the connection timer to expire
immediately.

However, before the timer callback, ip_vs_conn_expire(), is run
to clean the connection's conntrack entry, the new redistributed
connection may already be established and its conntrack removed
instead.

Fix this by dropping the first packet of the new connection
instead, like we do when the destination server is not available.
The timer will have deleted the old conntrack entry long before
the first packet of the new connection is retransmitted.

Fixes: dc7b3eb900aa ("ipvs: Fix reuse connection if real server is dead")
Signed-off-by: Jiri Bohac <redacted>
Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Simon Horman <horms@verge.net.au>
---
 include/net/ip_vs.h             | 17 +++++++++++++++++
 net/netfilter/ipvs/ip_vs_core.c | 37 ++++++++++++++++++++++++++++---------
 2 files changed, 45 insertions(+), 9 deletions(-)

diff --git a/include/net/ip_vs.h b/include/net/ip_vs.h
index 0816c872b689..a6cc576fd467 100644
--- a/include/net/ip_vs.h
+++ b/include/net/ip_vs.h

@@ -1588,6 +1588,23 @@ static inline void ip_vs_conn_drop_conntrack(struct ip_vs_conn *cp)
 }
 #endif /* CONFIG_IP_VS_NFCT */
 
+/* Really using conntrack? */
+static inline bool ip_vs_conn_uses_conntrack(struct ip_vs_conn *cp,
+					     struct sk_buff *skb)
+{
+#ifdef CONFIG_IP_VS_NFCT
+	enum ip_conntrack_info ctinfo;
+	struct nf_conn *ct;
+
+	if (!(cp->flags & IP_VS_CONN_F_NFCT))
+		return false;
+	ct = nf_ct_get(skb, &ctinfo);
+	if (ct && !nf_ct_is_untracked(ct))
+		return true;
+#endif
+	return false;
+}
+
 static inline int
 ip_vs_dest_conn_overhead(struct ip_vs_dest *dest)
 {

diff --git a/net/netfilter/ipvs/ip_vs_core.c b/net/netfilter/ipvs/ip_vs_core.c
index f57b4dcdb233..4da560005b0e 100644
--- a/net/netfilter/ipvs/ip_vs_core.c
+++ b/net/netfilter/ipvs/ip_vs_core.c

@@ -1757,15 +1757,34 @@ ip_vs_in(struct netns_ipvs *ipvs, unsigned int hooknum, struct sk_buff *skb, int
 	cp = pp->conn_in_get(ipvs, af, skb, &iph);
 
 	conn_reuse_mode = sysctl_conn_reuse_mode(ipvs);
-	if (conn_reuse_mode && !iph.fragoffs &&
-	    is_new_conn(skb, &iph) && cp &&
-	    ((unlikely(sysctl_expire_nodest_conn(ipvs)) && cp->dest &&
-	      unlikely(!atomic_read(&cp->dest->weight))) ||
-	     unlikely(is_new_conn_expected(cp, conn_reuse_mode)))) {
-		if (!atomic_read(&cp->n_control))
-			ip_vs_conn_expire_now(cp);
-		__ip_vs_conn_put(cp);
-		cp = NULL;
+	if (conn_reuse_mode && !iph.fragoffs && is_new_conn(skb, &iph) && cp) {
+		bool uses_ct = false, resched = false;
+
+		if (unlikely(sysctl_expire_nodest_conn(ipvs)) && cp->dest &&
+		    unlikely(!atomic_read(&cp->dest->weight))) {
+			resched = true;
+			uses_ct = ip_vs_conn_uses_conntrack(cp, skb);
+		} else if (is_new_conn_expected(cp, conn_reuse_mode)) {
+			uses_ct = ip_vs_conn_uses_conntrack(cp, skb);
+			if (!atomic_read(&cp->n_control)) {
+				resched = true;
+			} else {
+				/* Do not reschedule controlling connection
+				 * that uses conntrack while it is still
+				 * referenced by controlled connection(s).
+				 */
+				resched = !uses_ct;
+			}
+		}
+
+		if (resched) {
+			if (!atomic_read(&cp->n_control))
+				ip_vs_conn_expire_now(cp);
+			__ip_vs_conn_put(cp);
+			if (uses_ct)
+				return NF_DROP;
+			cp = NULL;
+		}
 	}
 
 	if (unlikely(!cp)) {

-- 
2.1.4

From: Julian Anastasov <ja@ssi.bg>

"RFC 5961, 4.2. Mitigation" describes a mechanism to request
client to confirm with RST the restart of TCP connection
before resending its SYN. As result, IPVS can see SYNs for
existing connection in CLOSE state. Add check to allow
rescheduling in this state.

Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Simon Horman <horms@verge.net.au>
---
 net/netfilter/ipvs/ip_vs_core.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/netfilter/ipvs/ip_vs_core.c b/net/netfilter/ipvs/ip_vs_core.c
index 4da560005b0e..b9a4082afa3a 100644
--- a/net/netfilter/ipvs/ip_vs_core.c
+++ b/net/netfilter/ipvs/ip_vs_core.c

@@ -1089,6 +1089,7 @@ static inline bool is_new_conn_expected(const struct ip_vs_conn *cp,
 	switch (cp->protocol) {
 	case IPPROTO_TCP:
 		return (cp->state == IP_VS_TCP_S_TIME_WAIT) ||
+		       (cp->state == IP_VS_TCP_S_CLOSE) ||
 			((conn_reuse_mode & 2) &&
 			 (cp->state == IP_VS_TCP_S_FIN_WAIT) &&
 			 (cp->flags & IP_VS_CONN_F_NOOUTPUT));

-- 
2.1.4

From: Marco Angaroni <redacted>

The IPVS SIP persistence engine is not able to parse the SIP header
"Call-ID" when such header is inserted in the first positions of
the SIP message.

When IPVS is configured with "--pe sip" option, like for example:
ipvsadm -A -u 1.2.3.4:5060 -s rr --pe sip -p 120 -o
some particular messages (see below for details) do not create entries
in the connection template table, which can be listed with:
ipvsadm -Lcn --persistent-conn

Problematic SIP messages are SIP responses having "Call-ID" header
positioned just after message first line:
SIP/2.0 200 OK
[Call-ID header here]
[rest of the headers]

When "Call-ID" header is positioned down (after a few other headers)
it is correctly recognized.

This is due to the data offset used in get_callid function call inside
ip_vs_pe_sip.c file: since dptr already points to the start of the
SIP message, the value of dataoff should be initially 0.
Otherwise the header is searched starting from some bytes after the
first character of the SIP message.

Fixes: 758ff0338722 ("IPVS: sip persistence engine")
Signed-off-by: Marco Angaroni <redacted>
Acked-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Simon Horman <horms@verge.net.au>
---
 net/netfilter/ipvs/ip_vs_pe_sip.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/netfilter/ipvs/ip_vs_pe_sip.c b/net/netfilter/ipvs/ip_vs_pe_sip.c
index c4e9ca016a88..0a6eb5c0d9e9 100644
--- a/net/netfilter/ipvs/ip_vs_pe_sip.c
+++ b/net/netfilter/ipvs/ip_vs_pe_sip.c

@@ -88,7 +88,7 @@ ip_vs_sip_fill_param(struct ip_vs_conn_param *p, struct sk_buff *skb)
 	dptr = skb->data + dataoff;
 	datalen = skb->len - dataoff;
 
-	if (get_callid(dptr, dataoff, datalen, &matchoff, &matchlen))
+	if (get_callid(dptr, 0, datalen, &matchoff, &matchlen))
 		return -EINVAL;
 
 	/* N.B: pe_data is only set on success,

-- 
2.1.4

On Mon, Mar 07, 2016 at 12:03:30PM +0900, Simon Horman wrote:

Hi Pablo,

please consider these IPVS fixes for v4.5 or
if it is too late please consider them for v4.6.

Pulled into nf-next, thanks Simon!