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net: sched: correct flower port blocking

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[ 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>
This commit is contained in:
Jason Baron 2020-02-17 15:38:09 -05:00 committed by Greg Kroah-Hartman
parent 781017047f
commit 5ed4c0b318
2 changed files with 10 additions and 0 deletions
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9
include/net/flow_dissector.h
View File

@ -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>
/**
@ -185,4 +186,12 @@ static inline bool flow_keys_have_l4(struct flow_keys *keys)
u32 flow_hash_from_keys(struct flow_keys *keys);
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

1
net/sched/cls_flower.c
View File

@ -127,6 +127,7 @@ static int fl_classify(struct sk_buff *skb, const struct tcf_proto *tp,
struct fl_flow_key skb_key;
struct fl_flow_key skb_mkey;
flow_dissector_init_keys(&skb_key.control, &skb_key.basic);
fl_clear_masked_range(&skb_key, &head->mask);
skb_key.indev_ifindex = skb->skb_iif;
/* skb_flow_dissect() does not set n_proto in case an unknown protocol,