[PATCH net] net/sched: cls_flower: fix only mask bit check in the validate_ct_state

From: wenxu <redacted>

The ct_state validate should not only check the mask bit and also
check the state bit.
For the +new+est case example, The 'new' and 'est' bits should be
set in both state_mask and state flags. Or the -new-est case also
will be reject by kernel.

Fixes: 	1bcc51ac0731 ("net/sched: cls_flower: Reject invalid ct_state flags rules")
Fixes: 	3aed8b63336c ("net/sched: cls_flower: validate ct_state for invalid and reply flags")
Signed-off-by: wenxu <redacted>
---
 net/sched/cls_flower.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
index d097b5c..92659e1 100644
--- a/net/sched/cls_flower.c
+++ b/net/sched/cls_flower.c

@@ -1401,31 +1401,37 @@ static int fl_set_enc_opt(struct nlattr **tb, struct fl_flow_key *key,
 	return 0;
 }
 
-static int fl_validate_ct_state(u16 state, struct nlattr *tb,
+static int fl_validate_ct_state(u16 state_mask, u16 state,
+				struct nlattr *tb,
 				struct netlink_ext_ack *extack)
 {
-	if (state && !(state & TCA_FLOWER_KEY_CT_FLAGS_TRACKED)) {
+	if (state_mask && !(state_mask & TCA_FLOWER_KEY_CT_FLAGS_TRACKED)) {
 		NL_SET_ERR_MSG_ATTR(extack, tb,
 				    "no trk, so no other flag can be set");
 		return -EINVAL;
 	}
 
-	if (state & TCA_FLOWER_KEY_CT_FLAGS_NEW &&
+	if (state_mask & TCA_FLOWER_KEY_CT_FLAGS_NEW &&
+	    state & TCA_FLOWER_KEY_CT_FLAGS_NEW &&
+	    state_mask & TCA_FLOWER_KEY_CT_FLAGS_ESTABLISHED &&
 	    state & TCA_FLOWER_KEY_CT_FLAGS_ESTABLISHED) {
 		NL_SET_ERR_MSG_ATTR(extack, tb,
 				    "new and est are mutually exclusive");
 		return -EINVAL;
 	}
 
-	if (state & TCA_FLOWER_KEY_CT_FLAGS_INVALID &&
-	    state & ~(TCA_FLOWER_KEY_CT_FLAGS_TRACKED |
+	if (state_mask & TCA_FLOWER_KEY_CT_FLAGS_INVALID &&
+	    state & TCA_FLOWER_KEY_CT_FLAGS_INVALID &&
+	    state_mask & ~(TCA_FLOWER_KEY_CT_FLAGS_TRACKED |
 		      TCA_FLOWER_KEY_CT_FLAGS_INVALID)) {
 		NL_SET_ERR_MSG_ATTR(extack, tb,
 				    "when inv is set, only trk may be set");
 		return -EINVAL;
 	}
 
-	if (state & TCA_FLOWER_KEY_CT_FLAGS_NEW &&
+	if (state_mask & TCA_FLOWER_KEY_CT_FLAGS_NEW &&
+	    state & TCA_FLOWER_KEY_CT_FLAGS_NEW &&
+	    state_mask & TCA_FLOWER_KEY_CT_FLAGS_REPLY &&
 	    state & TCA_FLOWER_KEY_CT_FLAGS_REPLY) {
 		NL_SET_ERR_MSG_ATTR(extack, tb,
 				    "new and rpl are mutually exclusive");

@@ -1451,7 +1457,7 @@ static int fl_set_key_ct(struct nlattr **tb,
 			       &mask->ct_state, TCA_FLOWER_KEY_CT_STATE_MASK,
 			       sizeof(key->ct_state));
 
-		err = fl_validate_ct_state(mask->ct_state,
+		err = fl_validate_ct_state(mask->ct_state, key->ct_state,
 					   tb[TCA_FLOWER_KEY_CT_STATE_MASK],
 					   extack);
 		if (err)

-- 
1.8.3.1

On Tue, 16 Mar 2021 15:44:17 +0800 wenxu@ucloud.cn wrote:

bitwise and operator chains well, BTW, so this could be written as:

	if (state & state_mask & TCA_FLOWER_KEY_CT_FLAGS_NEW &&
	    state & state_mask & TCA_FLOWER_KEY_CT_FLAGS_ESTABLISHED) {

+	    state_mask & TCA_FLOWER_KEY_CT_FLAGS_ESTABLISHED &&
 	    state & TCA_FLOWER_KEY_CT_FLAGS_ESTABLISHED) {
 		NL_SET_ERR_MSG_ATTR(extack, tb,
 				    "new and est are mutually exclusive");
 		return -EINVAL;
 	}
 
-	if (state & TCA_FLOWER_KEY_CT_FLAGS_INVALID &&
-	    state & ~(TCA_FLOWER_KEY_CT_FLAGS_TRACKED |
+	if (state_mask & TCA_FLOWER_KEY_CT_FLAGS_INVALID &&
+	    state & TCA_FLOWER_KEY_CT_FLAGS_INVALID &&
+	    state_mask & ~(TCA_FLOWER_KEY_CT_FLAGS_TRACKED |
 		      TCA_FLOWER_KEY_CT_FLAGS_INVALID)) {

nit: this needs to be realigned after opening bracket has moved

Hi,

On Tue, Mar 16, 2021 at 03:44:17PM +0800, wenxu@ucloud.cn wrote:

From: wenxu <redacted>

The ct_state validate should not only check the mask bit and also
check the state bit.
For the +new+est case example, The 'new' and 'est' bits should be
set in both state_mask and state flags. Or the -new-est case also
will be reject by kernel.

Please mention why +trk-new-est is expected.

Fixes: 	1bcc51ac0731 ("net/sched: cls_flower: Reject invalid ct_state flags rules")
Fixes: 	3aed8b63336c ("net/sched: cls_flower: validate ct_state for invalid and reply flags")

checkpatch.pl doesn't complain but I'm not sure if a tab is allowed here, btw.

The key/mask ordering is becoming messy in flower.
As this function gets called from fl_set_key_ct, please lets keep what was used
there: key, mask. Seems it's still the dominant one.
  static int fl_set_key_ct(struct nlattr **tb,
                           struct flow_dissector_key_ct *key,
                           struct flow_dissector_key_ct *mask,

On a similar note, I'm wondering if it worth just doing:
	u16 effective = state & state_mask;
To avoid this many checks below against key and mask simultaneously.

 				struct netlink_ext_ack *extack)
 {
-	if (state && !(state & TCA_FLOWER_KEY_CT_FLAGS_TRACKED)) {
+	if (state_mask && !(state_mask & TCA_FLOWER_KEY_CT_FLAGS_TRACKED)) {
 		NL_SET_ERR_MSG_ATTR(extack, tb,
 				    "no trk, so no other flag can be set");
 		return -EINVAL;
 	}
 
-	if (state & TCA_FLOWER_KEY_CT_FLAGS_NEW &&
+	if (state_mask & TCA_FLOWER_KEY_CT_FLAGS_NEW &&
+	    state & TCA_FLOWER_KEY_CT_FLAGS_NEW &&
+	    state_mask & TCA_FLOWER_KEY_CT_FLAGS_ESTABLISHED &&
 	    state & TCA_FLOWER_KEY_CT_FLAGS_ESTABLISHED) {
 		NL_SET_ERR_MSG_ATTR(extack, tb,
 				    "new and est are mutually exclusive");
 		return -EINVAL;
 	}
 
-	if (state & TCA_FLOWER_KEY_CT_FLAGS_INVALID &&
-	    state & ~(TCA_FLOWER_KEY_CT_FLAGS_TRACKED |
+	if (state_mask & TCA_FLOWER_KEY_CT_FLAGS_INVALID &&
+	    state & TCA_FLOWER_KEY_CT_FLAGS_INVALID &&
+	    state_mask & ~(TCA_FLOWER_KEY_CT_FLAGS_TRACKED |
 		      TCA_FLOWER_KEY_CT_FLAGS_INVALID)) {

An indent adjust here is welcomed.

Thanks,
Marcelo