We have targets and standard targets -- the latter carries a verdict, so we
must check the standard size as well here -- later functions access t->verdict
which otherwise can point after the blob end.
Spotted with UBSAN.
Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
---
include/linux/netfilter/x_tables.h | 3 +++
net/ipv4/netfilter/arp_tables.c | 11 +----------
net/ipv4/netfilter/ip_tables.c | 12 +-----------
net/ipv6/netfilter/ip6_tables.c | 12 +-----------
net/netfilter/x_tables.c | 22 ++++++++++++++++++++++
5 files changed, 28 insertions(+), 32 deletions(-)
diff --git a/include/linux/netfilter/x_tables.h b/include/linux/netfilter/x_tables.h
index 80a305b..9e7153e 100644
--- a/include/linux/netfilter/x_tables.h
+++ b/include/linux/netfilter/x_tables.h
@@ -413,6 +413,9 @@ xt_get_per_cpu_counter(struct xt_counters *cnt, unsigned int cpu)
struct nf_hook_ops *xt_hook_ops_alloc(const struct xt_table *, nf_hookfn *);
+int xt_check_entry_target(const void *base, unsigned int target_offset,
+ unsigned int next_offset);
+
#ifdef CONFIG_COMPAT
#include <net/compat.h>
diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c
index 51d4fe5..59a9610 100644
--- a/net/ipv4/netfilter/arp_tables.c
+++ b/net/ipv4/netfilter/arp_tables.c
@@ -476,19 +476,10 @@ next:
static inline int check_entry(const struct arpt_entry *e)
{
- const struct xt_entry_target *t;
-
if (!arp_checkentry(&e->arp))
return -EINVAL;
- if (e->target_offset + sizeof(struct xt_entry_target) > e->next_offset)
- return -EINVAL;
-
- t = arpt_get_target_c(e);
- if (e->target_offset + t->u.target_size > e->next_offset)
- return -EINVAL;
-
- return 0;
+ return xt_check_entry_target(e, e->target_offset, e->next_offset);
}
static inline int check_target(struct arpt_entry *e, const char *name)
diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index fb7694e..1acc6ee 100644
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -571,20 +571,10 @@ static void cleanup_match(struct xt_entry_match *m, struct net *net)
static int
check_entry(const struct ipt_entry *e)
{
- const struct xt_entry_target *t;
-
if (!ip_checkentry(&e->ip))
return -EINVAL;
- if (e->target_offset + sizeof(struct xt_entry_target) >
- e->next_offset)
- return -EINVAL;
-
- t = ipt_get_target_c(e);
- if (e->target_offset + t->u.target_size > e->next_offset)
- return -EINVAL;
-
- return 0;
+ return xt_check_entry_target(e, e->target_offset, e->next_offset);
}
static int
diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index b248528f..29e2113 100644
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -583,20 +583,10 @@ static void cleanup_match(struct xt_entry_match *m, struct net *net)
static int
check_entry(const struct ip6t_entry *e)
{
- const struct xt_entry_target *t;
-
if (!ip6_checkentry(&e->ipv6))
return -EINVAL;
- if (e->target_offset + sizeof(struct xt_entry_target) >
- e->next_offset)
- return -EINVAL;
-
- t = ip6t_get_target_c(e);
- if (e->target_offset + t->u.target_size > e->next_offset)
- return -EINVAL;
-
- return 0;
+ return xt_check_entry_target(e, e->target_offset, e->next_offset);
}
static int check_match(struct xt_entry_match *m, struct xt_mtchk_param *par)
diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c
index 582c9cf..c10f9b3 100644
--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c
@@ -541,6 +541,28 @@ int xt_compat_match_to_user(const struct xt_entry_match *m,
EXPORT_SYMBOL_GPL(xt_compat_match_to_user);
#endif /* CONFIG_COMPAT */
+/* check that arp/ip/ip6t_entry target_offset is sane */
+int xt_check_entry_target(const void *base, unsigned int target_offset,
+ unsigned int next_offset)
+{
+ const struct xt_entry_target *t;
+ const char *e = base;
+
+ if (target_offset + sizeof(struct xt_entry_target) > next_offset)
+ return -EINVAL;
+
+ t = (void *) (e + target_offset);
+ if (target_offset + t->u.target_size > next_offset)
+ return -EINVAL;
+
+ if (strcmp(t->u.user.name, XT_STANDARD_TARGET) == 0 &&
+ target_offset + sizeof(struct xt_standard_target) > next_offset)
+ return -EINVAL;
+
+ return 0;
+}
+EXPORT_SYMBOL(xt_check_entry_target);
+
int xt_check_target(struct xt_tgchk_param *par,
unsigned int size, u_int8_t proto, bool inv_proto)
{
--
2.4.10
--
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