diff options
Diffstat (limited to 'net/netfilter/nf_nat_proto_common.c')
-rw-r--r-- | net/netfilter/nf_nat_proto_common.c | 37 |
1 files changed, 25 insertions, 12 deletions
diff --git a/net/netfilter/nf_nat_proto_common.c b/net/netfilter/nf_nat_proto_common.c index 5d849d835561..234f535d350e 100644 --- a/net/netfilter/nf_nat_proto_common.c +++ b/net/netfilter/nf_nat_proto_common.c @@ -38,12 +38,12 @@ void nf_nat_l4proto_unique_tuple(const struct nf_nat_l3proto *l3proto, struct nf_conntrack_tuple *tuple, const struct nf_nat_range2 *range, enum nf_nat_manip_type maniptype, - const struct nf_conn *ct, - u16 *rover) + const struct nf_conn *ct) { - unsigned int range_size, min, max, i; + unsigned int range_size, min, max, i, attempts; __be16 *portptr; - u_int16_t off; + u16 off; + static const unsigned int max_attempts = 128; if (maniptype == NF_NAT_MANIP_SRC) portptr = &tuple->src.u.all; @@ -86,18 +86,31 @@ void nf_nat_l4proto_unique_tuple(const struct nf_nat_l3proto *l3proto, } else if (range->flags & NF_NAT_RANGE_PROTO_OFFSET) { off = (ntohs(*portptr) - ntohs(range->base_proto.all)); } else { - off = *rover; + off = prandom_u32(); } - for (i = 0; ; ++off) { + attempts = range_size; + if (attempts > max_attempts) + attempts = max_attempts; + + /* We are in softirq; doing a search of the entire range risks + * soft lockup when all tuples are already used. + * + * If we can't find any free port from first offset, pick a new + * one and try again, with ever smaller search window. + */ +another_round: + for (i = 0; i < attempts; i++, off++) { *portptr = htons(min + off % range_size); - if (++i != range_size && nf_nat_used_tuple(tuple, ct)) - continue; - if (!(range->flags & (NF_NAT_RANGE_PROTO_RANDOM_ALL| - NF_NAT_RANGE_PROTO_OFFSET))) - *rover = off; - return; + if (!nf_nat_used_tuple(tuple, ct)) + return; } + + if (attempts >= range_size || attempts < 16) + return; + attempts /= 2; + off = prandom_u32(); + goto another_round; } EXPORT_SYMBOL_GPL(nf_nat_l4proto_unique_tuple); |