ipvs: add sync_maxlen parameter for the sync daemon

Allow setups with large MTU to send large sync packets by
adding sync_maxlen parameter. The default value is now based
on MTU but no more than 1500 for compatibility reasons.

To avoid problems if MTU changes allow fragmentation by
sending packets with DF=0. Problem reported by Dan Carpenter.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Simon Horman <horms@verge.net.au>

include/net/ip_vs.h

@@ -846,6 +846,13 @@ struct ipvs_master_sync_state {
 /* How much time to keep dests in trash */
 #define IP_VS_DEST_TRASH_PERIOD		(120 * HZ)
 
+struct ipvs_sync_daemon_cfg {
+	int			syncid;
+	u16			sync_maxlen;
+	/* multicast interface name */
+	char			mcast_ifn[IP_VS_IFNAME_MAXLEN];
+};
+
 /* IPVS in network namespace */
 struct netns_ipvs {
 	int			gen;		/* Generation */
@@ -961,15 +968,10 @@ struct netns_ipvs {
 	spinlock_t		sync_buff_lock;
 	struct task_struct	**backup_threads;
 	int			threads_mask;
-	int			send_mesg_maxlen;
-	int			recv_mesg_maxlen;
 	volatile int		sync_state;
-	volatile int		master_syncid;
-	volatile int		backup_syncid;
 	struct mutex		sync_mutex;
-	/* multicast interface name */
-	char			master_mcast_ifn[IP_VS_IFNAME_MAXLEN];
-	char			backup_mcast_ifn[IP_VS_IFNAME_MAXLEN];
+	struct ipvs_sync_daemon_cfg	mcfg;	/* Master Configuration */
+	struct ipvs_sync_daemon_cfg	bcfg;	/* Backup Configuration */
 	/* net name space ptr */
 	struct net		*net;            /* Needed by timer routines */
 	/* Number of heterogeneous destinations, needed becaus heterogeneous
@@ -1408,7 +1410,8 @@ static inline void ip_vs_dest_put_and_free(struct ip_vs_dest *dest)
 /* IPVS sync daemon data and function prototypes
  * (from ip_vs_sync.c)
  */
-int start_sync_thread(struct net *net, int state, char *mcast_ifn, __u8 syncid);
+int start_sync_thread(struct net *net, struct ipvs_sync_daemon_cfg *cfg,
+		      int state);
 int stop_sync_thread(struct net *net, int state);
 void ip_vs_sync_conn(struct net *net, struct ip_vs_conn *cp, int pkts);
 

include/uapi/linux/ip_vs.h

@@ -406,6 +406,7 @@ enum {
 	IPVS_DAEMON_ATTR_STATE,		/* sync daemon state (master/backup) */
 	IPVS_DAEMON_ATTR_MCAST_IFN,	/* multicast interface name */
 	IPVS_DAEMON_ATTR_SYNC_ID,	/* SyncID we belong to */
+	IPVS_DAEMON_ATTR_SYNC_MAXLEN,	/* UDP Payload Size */
 	__IPVS_DAEMON_ATTR_MAX,
 };
 

net/netfilter/ipvs/ip_vs_ctl.c

@@ -2336,10 +2336,15 @@ do_ip_vs_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len)
 		struct ip_vs_daemon_user *dm = (struct ip_vs_daemon_user *)arg;
 
 		if (cmd == IP_VS_SO_SET_STARTDAEMON) {
+			struct ipvs_sync_daemon_cfg cfg;
+
+			memset(&cfg, 0, sizeof(cfg));
+			strlcpy(cfg.mcast_ifn, dm->mcast_ifn,
+				sizeof(cfg.mcast_ifn));
+			cfg.syncid = dm->syncid;
 			rtnl_lock();
 			mutex_lock(&ipvs->sync_mutex);
-			ret = start_sync_thread(net, dm->state, dm->mcast_ifn,
-						dm->syncid);
+			ret = start_sync_thread(net, &cfg, dm->state);
 			mutex_unlock(&ipvs->sync_mutex);
 			rtnl_unlock();
 		} else {
@@ -2650,15 +2655,15 @@ do_ip_vs_get_ctl(struct sock *sk, int cmd, void __user *user, int *len)
 		mutex_lock(&ipvs->sync_mutex);
 		if (ipvs->sync_state & IP_VS_STATE_MASTER) {
 			d[0].state = IP_VS_STATE_MASTER;
-			strlcpy(d[0].mcast_ifn, ipvs->master_mcast_ifn,
+			strlcpy(d[0].mcast_ifn, ipvs->mcfg.mcast_ifn,
 				sizeof(d[0].mcast_ifn));
-			d[0].syncid = ipvs->master_syncid;
+			d[0].syncid = ipvs->mcfg.syncid;
 		}
 		if (ipvs->sync_state & IP_VS_STATE_BACKUP) {
 			d[1].state = IP_VS_STATE_BACKUP;
-			strlcpy(d[1].mcast_ifn, ipvs->backup_mcast_ifn,
+			strlcpy(d[1].mcast_ifn, ipvs->bcfg.mcast_ifn,
 				sizeof(d[1].mcast_ifn));
-			d[1].syncid = ipvs->backup_syncid;
+			d[1].syncid = ipvs->bcfg.syncid;
 		}
 		if (copy_to_user(user, &d, sizeof(d)) != 0)
 			ret = -EFAULT;
@@ -2813,6 +2818,7 @@ static const struct nla_policy ip_vs_daemon_policy[IPVS_DAEMON_ATTR_MAX + 1] = {
 	[IPVS_DAEMON_ATTR_MCAST_IFN]	= { .type = NLA_NUL_STRING,
 					    .len = IP_VS_IFNAME_MAXLEN },
 	[IPVS_DAEMON_ATTR_SYNC_ID]	= { .type = NLA_U32 },
+	[IPVS_DAEMON_ATTR_SYNC_MAXLEN]	= { .type = NLA_U16 },
 };
 
 /* Policy used for attributes in nested attribute IPVS_CMD_ATTR_SERVICE */
@@ -3271,7 +3277,7 @@ static int ip_vs_genl_parse_dest(struct ip_vs_dest_user_kern *udest,
 }
 
 static int ip_vs_genl_fill_daemon(struct sk_buff *skb, __u32 state,
-				  const char *mcast_ifn, __u32 syncid)
+				  struct ipvs_sync_daemon_cfg *c)
 {
 	struct nlattr *nl_daemon;
 
@@ -3280,8 +3286,9 @@ static int ip_vs_genl_fill_daemon(struct sk_buff *skb, __u32 state,
 		return -EMSGSIZE;
 
 	if (nla_put_u32(skb, IPVS_DAEMON_ATTR_STATE, state) ||
-	    nla_put_string(skb, IPVS_DAEMON_ATTR_MCAST_IFN, mcast_ifn) ||
-	    nla_put_u32(skb, IPVS_DAEMON_ATTR_SYNC_ID, syncid))
+	    nla_put_string(skb, IPVS_DAEMON_ATTR_MCAST_IFN, c->mcast_ifn) ||
+	    nla_put_u32(skb, IPVS_DAEMON_ATTR_SYNC_ID, c->syncid) ||
+	    nla_put_u16(skb, IPVS_DAEMON_ATTR_SYNC_MAXLEN, c->sync_maxlen))
 		goto nla_put_failure;
 	nla_nest_end(skb, nl_daemon);
 
@@ -3293,7 +3300,7 @@ static int ip_vs_genl_fill_daemon(struct sk_buff *skb, __u32 state,
 }
 
 static int ip_vs_genl_dump_daemon(struct sk_buff *skb, __u32 state,
-				  const char *mcast_ifn, __u32 syncid,
+				  struct ipvs_sync_daemon_cfg *c,
 				  struct netlink_callback *cb)
 {
 	void *hdr;
@@ -3303,7 +3310,7 @@ static int ip_vs_genl_dump_daemon(struct sk_buff *skb, __u32 state,
 	if (!hdr)
 		return -EMSGSIZE;
 
-	if (ip_vs_genl_fill_daemon(skb, state, mcast_ifn, syncid))
+	if (ip_vs_genl_fill_daemon(skb, state, c))
 		goto nla_put_failure;
 
 	genlmsg_end(skb, hdr);
@@ -3323,17 +3330,15 @@ static int ip_vs_genl_dump_daemons(struct sk_buff *skb,
 	mutex_lock(&ipvs->sync_mutex);
 	if ((ipvs->sync_state & IP_VS_STATE_MASTER) && !cb->args[0]) {
 		if (ip_vs_genl_dump_daemon(skb, IP_VS_STATE_MASTER,
-					   ipvs->master_mcast_ifn,
-					   ipvs->master_syncid, cb) < 0)
+					   &ipvs->mcfg, cb) < 0)
 			goto nla_put_failure;
 
 		cb->args[0] = 1;
 	}
 
 	if ((ipvs->sync_state & IP_VS_STATE_BACKUP) && !cb->args[1]) {
 		if (ip_vs_genl_dump_daemon(skb, IP_VS_STATE_BACKUP,
-					   ipvs->backup_mcast_ifn,
-					   ipvs->backup_syncid, cb) < 0)
+					   &ipvs->bcfg, cb) < 0)
 			goto nla_put_failure;
 
 		cb->args[1] = 1;
@@ -3348,25 +3353,33 @@ static int ip_vs_genl_dump_daemons(struct sk_buff *skb,
 static int ip_vs_genl_new_daemon(struct net *net, struct nlattr **attrs)
 {
 	struct netns_ipvs *ipvs = net_ipvs(net);
+	struct ipvs_sync_daemon_cfg c;
+	struct nlattr *a;
 	int ret;
 
+	memset(&c, 0, sizeof(c));
 	if (!(attrs[IPVS_DAEMON_ATTR_STATE] &&
 	      attrs[IPVS_DAEMON_ATTR_MCAST_IFN] &&
 	      attrs[IPVS_DAEMON_ATTR_SYNC_ID]))
 		return -EINVAL;
+	strlcpy(c.mcast_ifn, nla_data(attrs[IPVS_DAEMON_ATTR_MCAST_IFN]),
+		sizeof(c.mcast_ifn));
+	c.syncid = nla_get_u32(attrs[IPVS_DAEMON_ATTR_SYNC_ID]);
+
+	a = attrs[IPVS_DAEMON_ATTR_SYNC_MAXLEN];
+	if (a)
+		c.sync_maxlen = nla_get_u16(a);
 
 	/* The synchronization protocol is incompatible with mixed family
 	 * services
 	 */
-	if (net_ipvs(net)->mixed_address_family_dests > 0)
+	if (ipvs->mixed_address_family_dests > 0)
 		return -EINVAL;
 
 	rtnl_lock();
 	mutex_lock(&ipvs->sync_mutex);
-	ret = start_sync_thread(net,
-				nla_get_u32(attrs[IPVS_DAEMON_ATTR_STATE]),
-				nla_data(attrs[IPVS_DAEMON_ATTR_MCAST_IFN]),
-				nla_get_u32(attrs[IPVS_DAEMON_ATTR_SYNC_ID]));
+	ret = start_sync_thread(net, &c,
+				nla_get_u32(attrs[IPVS_DAEMON_ATTR_STATE]));
 	mutex_unlock(&ipvs->sync_mutex);
 	rtnl_unlock();
 	return ret;