On Sun, Aug 21, 2016 at 05:28:57PM +0200, Willy Tarreau wrote: > From: Florian Westphal <[email protected]> > > commit 36472341017529e2b12573093cc0f68719300997 upstream. > > When we see a jump also check that the offset gets us to beginning of > a rule (an ipt_entry). (...)
Sorry, this patch is bad and causes performance issues, I didn't notice that 3.14 had a different version, below. Thanks to Jay for reporting the problem to me. I'll push 3.10.103-rc2 after some cool down period. Willy ---- >From 3c079e0993ca3bdd94dddd028ee04c85911aa666 Mon Sep 17 00:00:00 2001 From: Florian Westphal <[email protected]> Date: Fri, 1 Apr 2016 14:17:22 +0200 Subject: netfilter: x_tables: validate targets of jumps commit 36472341017529e2b12573093cc0f68719300997 upstream. 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 <[email protected]> Signed-off-by: Pablo Neira Ayuso <[email protected]> [wt: pick the patch from 3.14, it slightly differs to address the issue described here : https://patchwork.ozlabs.org/patch/650121/] Signed-off-by: Willy Tarreau <[email protected]> --- net/ipv4/netfilter/arp_tables.c | 17 +++++++++++++++++ net/ipv4/netfilter/ip_tables.c | 17 +++++++++++++++++ net/ipv6/netfilter/ip6_tables.c | 17 +++++++++++++++++ 3 files changed, 51 insertions(+) diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c index 7460b7b..473ec55 100644 --- a/net/ipv4/netfilter/arp_tables.c +++ b/net/ipv4/netfilter/arp_tables.c @@ -358,6 +358,19 @@ static inline bool unconditional(const struct arpt_entry *e) memcmp(&e->arp, &uncond, sizeof(uncond)) == 0; } +static bool find_jump_target(const struct xt_table_info *t, + const void *entry0, + const struct arpt_entry *target) +{ + struct arpt_entry *iter; + + xt_entry_foreach(iter, entry0, 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. */ @@ -451,6 +464,10 @@ static int mark_source_chains(const struct xt_table_info *newinfo, /* This a jump; chase it. */ duprintf("Jump rule %u -> %u\n", pos, newpos); + e = (struct arpt_entry *) + (entry0 + newpos); + if (!find_jump_target(newinfo, entry0, e)) + return 0; } else { /* ... this is a fallthru */ newpos = pos + e->next_offset; diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c index 8fc22ee..dba9d80 100644 --- a/net/ipv4/netfilter/ip_tables.c +++ b/net/ipv4/netfilter/ip_tables.c @@ -434,6 +434,19 @@ ipt_do_table(struct sk_buff *skb, #endif } +static bool find_jump_target(const struct xt_table_info *t, + const void *entry0, + const struct ipt_entry *target) +{ + struct ipt_entry *iter; + + xt_entry_foreach(iter, entry0, 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 @@ -531,6 +544,10 @@ mark_source_chains(const struct xt_table_info *newinfo, /* This a jump; chase it. */ duprintf("Jump rule %u -> %u\n", pos, newpos); + e = (struct ipt_entry *) + (entry0 + newpos); + if (!find_jump_target(newinfo, entry0, e)) + return 0; } else { /* ... this is a fallthru */ newpos = pos + e->next_offset; diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c index 63f7876..97a8d25 100644 --- a/net/ipv6/netfilter/ip6_tables.c +++ b/net/ipv6/netfilter/ip6_tables.c @@ -444,6 +444,19 @@ ip6t_do_table(struct sk_buff *skb, #endif } +static bool find_jump_target(const struct xt_table_info *t, + const void *entry0, + const struct ip6t_entry *target) +{ + struct ip6t_entry *iter; + + xt_entry_foreach(iter, entry0, 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 @@ -541,6 +554,10 @@ 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, entry0, e)) + return 0; } else { /* ... this is a fallthru */ newpos = pos + e->next_offset; -- 2.8.0.rc2.1.gbe9624a
