This is a note to let you know that I've just added the patch titled
netfilter: x_tables: validate targets of jumps
to the 4.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
netfilter-x_tables-validate-targets-of-jumps.patch
and it can be found in the queue-4.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 36472341017529e2b12573093cc0f68719300997 Mon Sep 17 00:00:00 2001
From: Florian Westphal <fw@xxxxxxxxx>
Date: Fri, 1 Apr 2016 14:17:22 +0200
Subject: netfilter: x_tables: validate targets of jumps
From: Florian Westphal <fw@xxxxxxxxx>
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@xxxxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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
@@ -367,6 +367,18 @@ 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 struct arpt_entry *target)
+{
+ struct arpt_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.
*/
@@ -460,6 +472,10 @@ 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, 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
@@ -443,6 +443,18 @@ ipt_do_table(struct sk_buff *skb,
#endif
}
+static bool find_jump_target(const struct xt_table_info *t,
+ const struct ipt_entry *target)
+{
+ struct ipt_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
@@ -540,6 +552,10 @@ 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, 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
@@ -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
/* 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;
Patches currently in stable-queue which might be from fw@xxxxxxxxx are
queue-4.6/netfilter-x_tables-add-and-use-xt_check_entry_offsets.patch
queue-4.6/netfilter-x_tables-assert-minimum-target-size.patch
queue-4.6/netfilter-x_tables-add-compat-version-of-xt_check_entry_offsets.patch
queue-4.6/netfilter-x_tables-check-for-bogus-target-offset.patch
queue-4.6/netfilter-x_tables-validate-targets-of-jumps.patch
queue-4.6/netfilter-x_tables-don-t-move-to-non-existent-next-rule.patch
queue-4.6/netfilter-x_tables-kill-check_entry-helper.patch
queue-4.6/netfilter-x_tables-check-standard-target-size-too.patch
queue-4.6/netfilter-x_tables-validate-all-offsets-and-sizes-in-a-rule.patch
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