diff options
| author | Jan Engelhardt <jengelh@medozas.de> | 2009-07-09 22:54:53 +0200 |
|---|---|---|
| committer | Jan Engelhardt <jengelh@medozas.de> | 2009-08-10 13:35:29 +0200 |
| commit | 90e7d4ab5c8b0c4c2e00e4893977f6aeec0f18f1 (patch) | |
| tree | 81951e3cb17713cd0cedfec9d4d3823d3fe264f5 /net/ipv4 | |
| parent | a7d51738e757c1ab94595e7d05594c61f0fb32ce (diff) | |
netfilter: xtables: check for unconditionality of policies
This adds a check that iptables's original author Rusty set forth in
a FIXME comment.
Underflows in iptables are better known as chain policies, and are
required to be unconditional or there would be a stochastical chance
for the policy rule to be skipped if it does not match. If that were
to happen, rule execution would continue in an unexpected spurious
fashion.
Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
Diffstat (limited to 'net/ipv4')
| -rw-r--r-- | net/ipv4/netfilter/arp_tables.c | 12 | ||||
| -rw-r--r-- | net/ipv4/netfilter/ip_tables.c | 11 |
2 files changed, 14 insertions, 9 deletions
diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c index d91f0834d57..064082dffaf 100644 --- a/net/ipv4/netfilter/arp_tables.c +++ b/net/ipv4/netfilter/arp_tables.c @@ -8,7 +8,7 @@ * Copyright (C) 2002 David S. Miller (davem@redhat.com) * */ - +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/kernel.h> #include <linux/skbuff.h> #include <linux/netdevice.h> @@ -563,13 +563,15 @@ static inline int check_entry_size_and_hooks(struct arpt_entry *e, continue; if ((unsigned char *)e - base == hook_entries[h]) newinfo->hook_entry[h] = hook_entries[h]; - if ((unsigned char *)e - base == underflows[h]) + if ((unsigned char *)e - base == underflows[h]) { + if (!unconditional(&e->arp)) { + pr_err("Underflows must be unconditional\n"); + return -EINVAL; + } newinfo->underflow[h] = underflows[h]; + } } - /* FIXME: underflows must be unconditional, standard verdicts - < 0 (not ARPT_RETURN). --RR */ - /* Clear counters and comefrom */ e->counters = ((struct xt_counters) { 0, 0 }); e->comefrom = 0; diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c index 6e7b7e8b80b..6e546d573d9 100644 --- a/net/ipv4/netfilter/ip_tables.c +++ b/net/ipv4/netfilter/ip_tables.c @@ -8,6 +8,7 @@ * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/cache.h> #include <linux/capability.h> #include <linux/skbuff.h> @@ -738,13 +739,15 @@ check_entry_size_and_hooks(struct ipt_entry *e, continue; if ((unsigned char *)e - base == hook_entries[h]) newinfo->hook_entry[h] = hook_entries[h]; - if ((unsigned char *)e - base == underflows[h]) + if ((unsigned char *)e - base == underflows[h]) { + if (!unconditional(&e->ip)) { + pr_err("Underflows must be unconditional\n"); + return -EINVAL; + } newinfo->underflow[h] = underflows[h]; + } } - /* FIXME: underflows must be unconditional, standard verdicts - < 0 (not IPT_RETURN). --RR */ - /* Clear counters and comefrom */ e->counters = ((struct xt_counters) { 0, 0 }); e->comefrom = 0; |