net: sched: correct flower port blocking

[ Upstream commit 8a9093c79863b58cc2f9874d7ae788f0d622a596 ]

tc flower rules that are based on src or dst port blocking are sometimes
ineffective due to uninitialized stack data. __skb_flow_dissect() extracts
ports from the skb for tc flower to match against. However, the port
dissection is not done when when the FLOW_DIS_IS_FRAGMENT bit is set in
key_control->flags. All callers of __skb_flow_dissect(), zero-out the
key_control field except for fl_classify() as used by the flower
classifier. Thus, the FLOW_DIS_IS_FRAGMENT may be set on entry to
__skb_flow_dissect(), since key_control is allocated on the stack
and may not be initialized.

Since key_basic and key_control are present for all flow keys, let's
make sure they are initialized.

Fixes: 62230715fd24 ("flow_dissector: do not dissect l4 ports for fragments")
Co-developed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: Jason Baron <jbaron@akamai.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/include/net/flow_dissector.h b/include/net/flow_dissector.h
index 1505cf7a4aafa4bbdb395f0e6ecefc34dd9022a5..7a85a4ef6868e47a9e84022dbc893b858e3d1a62 100644 (file)
--- a/include/net/flow_dissector.h
+++ b/include/net/flow_dissector.h
@@ -4,6 +4,7 @@
 #include <linux/types.h>
 #include <linux/in6.h>
 #include <linux/siphash.h>
+#include <linux/string.h>
 #include <uapi/linux/if_ether.h>
 
 /**
@@ -204,4 +205,12 @@ static inline void *skb_flow_dissector_target(struct flow_dissector *flow_dissec
        return ((char *)target_container) + flow_dissector->offset[key_id];
 }
 
+static inline void
+flow_dissector_init_keys(struct flow_dissector_key_control *key_control,
+                        struct flow_dissector_key_basic *key_basic)
+{
+       memset(key_control, 0, sizeof(*key_control));
+       memset(key_basic, 0, sizeof(*key_basic));
+}
+
 #endif

diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
index de03b7b49e050d22dfd7b91cc2bba1d8ab9bab39..18904313bd4e6b7c0b286b33db0f89776a5c7b9b 100644 (file)
--- a/net/sched/cls_flower.c
+++ b/net/sched/cls_flower.c
@@ -141,6 +141,7 @@ static int fl_classify(struct sk_buff *skb, const struct tcf_proto *tp,
        if (!atomic_read(&head->ht.nelems))
                return -1;
 
+       flow_dissector_init_keys(&skb_key.control, &skb_key.basic);
        fl_clear_masked_range(&skb_key, &head->mask);
 
        info = skb_tunnel_info(skb);