| From | Ben Hutchings <> | Date | Mon, 14 Nov 2016 00:14:20 +0000 | Subject | [PATCH 3.16 083/346] netfilter: x_tables: validate targets of jumps |
| |
3.16.39-rc1 review patch. If anyone has any objections, please let me know.
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From: Florian Westphal <fw@strlen.de>
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 <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- 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;
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