--- a/net/ipv4/netfilter/ip_tables.c +++ b/net/ipv4/netfilter/ip_tables.c @@ -308,6 +308,33 @@ struct ipt_entry *ipt_next_entry(const s return (void *)entry + entry->next_offset; } +static bool +ipt_handle_default_rule(struct ipt_entry *e, unsigned int *verdict) +{ + struct xt_entry_target *t; + struct xt_standard_target *st; + + if (e->target_offset != sizeof(struct ipt_entry)) + return false; + + if (!(e->ip.flags & IPT_F_NO_DEF_MATCH)) + return false; + + t = ipt_get_target(e); + if (t->u.kernel.target->target) + return false; + + st = (struct xt_standard_target *) t; + if (st->verdict == XT_RETURN) + return false; + + if (st->verdict >= 0) + return false; + + *verdict = (unsigned)(-st->verdict) - 1; + return true; +} + /* Returns one of the generic firewall policies, like NF_ACCEPT. */ unsigned int ipt_do_table(struct sk_buff *skb, @@ -328,27 +355,8 @@ ipt_do_table(struct sk_buff *skb, unsigned int addend; /* Initialization */ - stackidx = 0; - ip = ip_hdr(skb); - indev = state->in ? state->in->name : nulldevname; - outdev = state->out ? state->out->name : nulldevname; - /* We handle fragments by dealing with the first fragment as - * if it was a normal packet. All other fragments are treated - * normally, except that they will NEVER match rules that ask - * things we don't know, ie. tcp syn flag or ports). If the - * rule is also a fragment-specific rule, non-fragments won't - * match it. */ - acpar.fragoff = ntohs(ip->frag_off) & IP_OFFSET; - acpar.thoff = ip_hdrlen(skb); - acpar.hotdrop = false; - acpar.in = state->in; - acpar.out = state->out; - acpar.family = NFPROTO_IPV4; - acpar.hooknum = hook; - IP_NF_ASSERT(table->valid_hooks & (1 << hook)); local_bh_disable(); - addend = xt_write_recseq_begin(); private = table->private; cpu = smp_processor_id(); /* @@ -357,6 +365,20 @@ ipt_do_table(struct sk_buff *skb, */ smp_read_barrier_depends(); table_base = private->entries; + + e = get_entry(table_base, private->hook_entry[hook]); + if (ipt_handle_default_rule(e, &verdict)) { + ADD_COUNTER(e->counters, skb->len, 1); + local_bh_enable(); + return verdict; + } + + stackidx = 0; + ip = ip_hdr(skb); + indev = state->in ? state->in->name : nulldevname; + outdev = state->out ? state->out->name : nulldevname; + + addend = xt_write_recseq_begin(); jumpstack = (struct ipt_entry **)private->jumpstack[cpu]; /* Switch to alternate jumpstack if we're being invoked via TEE. @@ -369,7 +391,19 @@ ipt_do_table(struct sk_buff *skb, if (static_key_false(&xt_tee_enabled)) jumpstack += private->stacksize * __this_cpu_read(nf_skb_duplicated); - e = get_entry(table_base, private->hook_entry[hook]); + /* We handle fragments by dealing with the first fragment as + * if it was a normal packet. All other fragments are treated + * normally, except that they will NEVER match rules that ask + * things we don't know, ie. tcp syn flag or ports). If the + * rule is also a fragment-specific rule, non-fragments won't + * match it. */ + acpar.fragoff = ntohs(ip->frag_off) & IP_OFFSET; + acpar.thoff = ip_hdrlen(skb); + acpar.hotdrop = false; + acpar.in = state->in; + acpar.out = state->out; + acpar.family = NFPROTO_IPV4; + acpar.hooknum = hook; pr_debug("Entering %s(hook %u), UF %p\n", table->name, hook,