From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966281AbcKND7N (ORCPT ); Sun, 13 Nov 2016 22:59:13 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:45068 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752294AbcKNCEN (ORCPT ); Sun, 13 Nov 2016 21:04:13 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Greg Kroah-Hartman" , "Florian Westphal" , "Pablo Neira Ayuso" Date: Mon, 14 Nov 2016 00:14:20 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 083/346] netfilter: x_tables: validate targets of jumps In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.39-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Florian Westphal 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 Signed-off-by: Pablo Neira Ayuso Signed-off-by: Greg Kroah-Hartman Signed-off-by: Ben Hutchings --- net/ipv4/netfilter/arp_tables.c | 16 ++++++++++++++++ net/ipv4/netfilter/ip_tables.c | 16 ++++++++++++++++ net/ipv6/netfilter/ip6_tables.c | 16 ++++++++++++++++ 3 files changed, 48 insertions(+) --- a/net/ipv4/netfilter/arp_tables.c +++ b/net/ipv4/netfilter/arp_tables.c @@ -363,6 +363,19 @@ static inline bool unconditional(const s 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. */ @@ -456,6 +469,10 @@ static int mark_source_chains(const stru /* 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; --- a/net/ipv4/netfilter/ip_tables.c +++ b/net/ipv4/netfilter/ip_tables.c @@ -439,6 +439,19 @@ 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 @@ -536,6 +549,10 @@ mark_source_chains(const struct xt_table /* 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; --- a/net/ipv6/netfilter/ip6_tables.c +++ b/net/ipv6/netfilter/ip6_tables.c @@ -449,6 +449,19 @@ 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 @@ -546,6 +559,10 @@ mark_source_chains(const struct xt_table /* 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;