When we see a jump also check that the offset gets us to a beginning of
a rule (an ipt_entry).
Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
---
net/ipv4/netfilter/arp_tables.c | 14 ++++++++++++++
net/ipv4/netfilter/ip_tables.c | 14 ++++++++++++++
net/ipv6/netfilter/ip6_tables.c | 14 ++++++++++++++
3 files changed, 42 insertions(+)
diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c
index 2347a5c..378ea80 100644
--- a/net/ipv4/netfilter/arp_tables.c
+++ b/net/ipv4/netfilter/arp_tables.c
@@ -366,6 +366,18 @@ static inline bool unconditional(const struct arpt_arp *arp)
return memcmp(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.
*/
@@ -462,6 +474,8 @@ static int mark_source_chains(const struct xt_table_info *newinfo,
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;
diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index 07ce901..5d66c55 100644
--- 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
@@ -543,6 +555,8 @@ mark_source_chains(const struct xt_table_info *newinfo,
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;
diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index 99068dc..6fc671c 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
@@ -555,6 +567,8 @@ mark_source_chains(const struct xt_table_info *newinfo,
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;
--
2.4.10
--
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