@@ -72,8 +72,11 @@ static unsigned int nf_nat_ftp(struct sk_buff *skb,
u_int16_t port;
int dir = CTINFO2DIR(ctinfo);
struct nf_conn *ct = exp->master;
+ unsigned int i, min, max, range_size;
+ static const unsigned int max_attempts = 128;
char buffer[sizeof("|1||65535|") + INET6_ADDRSTRLEN];
unsigned int buflen;
+ int ret;
pr_debug("type %i, off %u len %u\n", type, matchoff, matchlen);
@@ -86,22 +89,32 @@ static unsigned int nf_nat_ftp(struct sk_buff *skb,
* this one. */
exp->expectfn = nf_nat_follow_master;
- /* Try to get same port: if not, try to change it. */
- for (port = ntohs(exp->saved_proto.tcp.port); port != 0; port++) {
- int ret;
-
- exp->tuple.dst.u.tcp.port = htons(port);
- ret = nf_ct_expect_related(exp, 0);
- if (ret == 0)
- break;
- else if (ret != -EBUSY) {
- port = 0;
- break;
+ min = ntohs(exp->saved_proto.tcp.port);
+ max = 65535;
+
+ /* Try to get same port */
+ ret = nf_ct_expect_related(exp, 0);
+
+ /* if same port is not in range or available, try to change it. */
+ if (ret != 0) {
+ range_size = max - min + 1;
+ if (range_size > max_attempts)
+ range_size = max_attempts;
+
+ port = min + prandom_u32_max(max - min);
+ for (i = 0; i < range_size; i++) {
+ exp->tuple.dst.u.tcp.port = htons(port);
+ ret = nf_ct_expect_related(exp, 0);
+ if (ret != -EBUSY)
+ break;
+ port++;
+ if (port > max)
+ port = min;
}
}
- if (port == 0) {
- nf_ct_helper_log(skb, ct, "all ports in use");
+ if (ret != 0) {
+ nf_ct_helper_log(skb, ct, "tried %u ports, all were in use", range_size);
return NF_DROP;
}