diff options
| author | Florian Westphal <fw@strlen.de> | 2016-04-01 15:17:22 +0300 |
|---|---|---|
| committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2016-04-14 01:30:35 +0300 |
| commit | 36472341017529e2b12573093cc0f68719300997 (patch) | |
| tree | 96f6dd9fbfcddc5e3a934d4dd812d640574897d0 /net/ipv6 | |
| parent | f24e230d257af1ad7476c6e81a8dc3127a74204e (diff) | |
| download | linux-36472341017529e2b12573093cc0f68719300997.tar.xz | |
netfilter: x_tables: validate targets of jumps
When we see a jump also check that the offset gets us to beginning of
a rule (an ipt_entry).
The extra overhead is negible, even with absurd cases.
300k custom rules, 300k jumps to 'next' user chain:
[ plus one jump from INPUT to first userchain ]:
Before:
real 0m24.874s
user 0m7.532s
sys 0m16.076s
After:
real 0m27.464s
user 0m7.436s
sys 0m18.840s
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net/ipv6')
| -rw-r--r-- | net/ipv6/netfilter/ip6_tables.c | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c index 7b3335bce3fd..126f2a0f006a 100644 --- a/net/ipv6/netfilter/ip6_tables.c +++ b/net/ipv6/netfilter/ip6_tables.c @@ -455,6 +455,18 @@ ip6t_do_table(struct sk_buff *skb, #endif } +static bool find_jump_target(const struct xt_table_info *t, + const struct ip6t_entry *target) +{ + struct ip6t_entry *iter; + + xt_entry_foreach(iter, t->entries, t->size) { + if (iter == target) + return true; + } + return false; +} + /* Figures out from what hook each rule can be called: returns 0 if there are loops. Puts hook bitmask in comefrom. */ static int @@ -552,6 +564,10 @@ mark_source_chains(const struct xt_table_info *newinfo, /* This a jump; chase it. */ duprintf("Jump rule %u -> %u\n", pos, newpos); + e = (struct ip6t_entry *) + (entry0 + newpos); + if (!find_jump_target(newinfo, e)) + return 0; } else { /* ... this is a fallthru */ newpos = pos + e->next_offset; |