[PATCH net-next v4 0/3] net/sched: act_vlan: Fix modify to allow 0

[PATCH net-next v4 0/3] net/sched: act_vlan: Fix modify to allow 0

[Boris Sukholitko]

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Currently vlan modification action checks existence of vlan priority by
comparing it to 0. Therefore it is impossible to modify existing vlan
tag to have priority 0.

For example, the following tc command will change the vlan id but will
not affect vlan priority:

tc filter add dev eth1 ingress matchall action vlan modify id 300 \
        priority 0 pipe mirred egress redirect dev eth2

The incoming packet on eth1:

ethertype 802.1Q (0x8100), vlan 200, p 4, ethertype IPv4

will be changed to:

ethertype 802.1Q (0x8100), vlan 300, p 4, ethertype IPv4

although the user has intended to have p == 0.

The fix is to add tcfv_push_prio_exists flag to struct tcf_vlan_params
and rely on it when deciding to set the priority.

The same flag is used to avoid dumping unset vlan priority.

Change Log:
v3 -> v4:
- revert tcf_vlan_get_fill_size change: total size calculation may race vs dump

v2 -> v3:
- Push assumes that the priority is being set
- tcf_vlan_get_fill_size accounts for priority existence

v1 -> v2:
- Do not dump unset priority and fix tests accordingly
- Test for priority 0 modification

Boris Sukholitko (3):
  net/sched: act_vlan: Fix modify to allow 0
  net/sched: act_vlan: No dump for unset priority
  net/sched: act_vlan: Test priority 0 modification

 include/net/tc_act/tc_vlan.h                  |  1 +
 net/sched/act_vlan.c                          | 11 +++++---
 .../tc-testing/tc-tests/actions/vlan.json     | 28 +++++++++++++++++--
 3 files changed, 34 insertions(+), 6 deletions(-)

-- 
2.29.3


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[PATCH net-next v4 1/3] net/sched: act_vlan: Fix modify to allow 0

[Boris Sukholitko]

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Currently vlan modification action checks existence of vlan priority by
comparing it to 0. Therefore it is impossible to modify existing vlan
tag to have priority 0.

For example, the following tc command will change the vlan id but will
not affect vlan priority:

tc filter add dev eth1 ingress matchall action vlan modify id 300 \
        priority 0 pipe mirred egress redirect dev eth2

The incoming packet on eth1:

ethertype 802.1Q (0x8100), vlan 200, p 4, ethertype IPv4

will be changed to:

ethertype 802.1Q (0x8100), vlan 300, p 4, ethertype IPv4

although the user has intended to have p == 0.

The fix is to add tcfv_push_prio_exists flag to struct tcf_vlan_params
and rely on it when deciding to set the priority.

Fixes: 45a497f2d149a4a8061c (net/sched: act_vlan: Introduce TCA_VLAN_ACT_MODIFY vlan action)
Signed-off-by: Boris Sukholitko <boris.sukholitko@broadcom.com>
---
 include/net/tc_act/tc_vlan.h | 1 +
 net/sched/act_vlan.c         | 7 +++++--
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/include/net/tc_act/tc_vlan.h b/include/net/tc_act/tc_vlan.h
index f051046ba034..f94b8bc26f9e 100644
--- a/include/net/tc_act/tc_vlan.h
+++ b/include/net/tc_act/tc_vlan.h
@@ -16,6 +16,7 @@ struct tcf_vlan_params {
 	u16               tcfv_push_vid;
 	__be16            tcfv_push_proto;
 	u8                tcfv_push_prio;
+	bool              tcfv_push_prio_exists;
 	struct rcu_head   rcu;
 };
 
diff --git a/net/sched/act_vlan.c b/net/sched/act_vlan.c
index 1cac3c6fbb49..a108469c664f 100644
--- a/net/sched/act_vlan.c
+++ b/net/sched/act_vlan.c
@@ -70,7 +70,7 @@ static int tcf_vlan_act(struct sk_buff *skb, const struct tc_action *a,
 		/* replace the vid */
 		tci = (tci & ~VLAN_VID_MASK) | p->tcfv_push_vid;
 		/* replace prio bits, if tcfv_push_prio specified */
-		if (p->tcfv_push_prio) {
+		if (p->tcfv_push_prio_exists) {
 			tci &= ~VLAN_PRIO_MASK;
 			tci |= p->tcfv_push_prio << VLAN_PRIO_SHIFT;
 		}
@@ -121,6 +121,7 @@ static int tcf_vlan_init(struct net *net, struct nlattr *nla,
 	struct tc_action_net *tn = net_generic(net, vlan_net_id);
 	struct nlattr *tb[TCA_VLAN_MAX + 1];
 	struct tcf_chain *goto_ch = NULL;
+	bool push_prio_exists = false;
 	struct tcf_vlan_params *p;
 	struct tc_vlan *parm;
 	struct tcf_vlan *v;
@@ -189,7 +190,8 @@ static int tcf_vlan_init(struct net *net, struct nlattr *nla,
 			push_proto = htons(ETH_P_8021Q);
 		}
 
-		if (tb[TCA_VLAN_PUSH_VLAN_PRIORITY])
+		push_prio_exists = !!tb[TCA_VLAN_PUSH_VLAN_PRIORITY];
+		if (push_prio_exists)
 			push_prio = nla_get_u8(tb[TCA_VLAN_PUSH_VLAN_PRIORITY]);
 		break;
 	case TCA_VLAN_ACT_POP_ETH:
@@ -241,6 +243,7 @@ static int tcf_vlan_init(struct net *net, struct nlattr *nla,
 	p->tcfv_action = action;
 	p->tcfv_push_vid = push_vid;
 	p->tcfv_push_prio = push_prio;
+	p->tcfv_push_prio_exists = push_prio_exists || action == TCA_VLAN_ACT_PUSH;
 	p->tcfv_push_proto = push_proto;
 
 	if (action == TCA_VLAN_ACT_PUSH_ETH) {
-- 
2.29.3


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[PATCH net-next v4 2/3] net/sched: act_vlan: No dump for unset priority

[Boris Sukholitko]

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Dump vlan priority only if it has been previously set.

Fix the tests accordingly.

Signed-off-by: Boris Sukholitko <boris.sukholitko@broadcom.com>
---
 net/sched/act_vlan.c                                          | 4 ++--
 tools/testing/selftests/tc-testing/tc-tests/actions/vlan.json | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/net/sched/act_vlan.c b/net/sched/act_vlan.c
index a108469c664f..71f2015c70ca 100644
--- a/net/sched/act_vlan.c
+++ b/net/sched/act_vlan.c
@@ -307,8 +307,8 @@ static int tcf_vlan_dump(struct sk_buff *skb, struct tc_action *a,
 	    (nla_put_u16(skb, TCA_VLAN_PUSH_VLAN_ID, p->tcfv_push_vid) ||
 	     nla_put_be16(skb, TCA_VLAN_PUSH_VLAN_PROTOCOL,
 			  p->tcfv_push_proto) ||
-	     (nla_put_u8(skb, TCA_VLAN_PUSH_VLAN_PRIORITY,
-					      p->tcfv_push_prio))))
+	     (p->tcfv_push_prio_exists &&
+	      nla_put_u8(skb, TCA_VLAN_PUSH_VLAN_PRIORITY, p->tcfv_push_prio))))
 		goto nla_put_failure;
 
 	if (p->tcfv_action == TCA_VLAN_ACT_PUSH_ETH) {
diff --git a/tools/testing/selftests/tc-testing/tc-tests/actions/vlan.json b/tools/testing/selftests/tc-testing/tc-tests/actions/vlan.json
index 527ce5410314..1d9d261aa0b3 100644
--- a/tools/testing/selftests/tc-testing/tc-tests/actions/vlan.json
+++ b/tools/testing/selftests/tc-testing/tc-tests/actions/vlan.json
@@ -463,7 +463,7 @@
         "cmdUnderTest": "$TC actions add action vlan modify protocol 802.1Q id 5 index 100",
         "expExitCode": "0",
         "verifyCmd": "$TC actions get action vlan index 100",
-        "matchPattern": "action order [0-9]+: vlan.*modify id 100 protocol 802.1Q priority 0 pipe.*index 100 ref",
+        "matchPattern": "action order [0-9]+: vlan.*modify id 100 protocol 802.1Q pipe.*index 100 ref",
         "matchCount": "0",
         "teardown": [
             "$TC actions flush action vlan"
@@ -487,7 +487,7 @@
         "cmdUnderTest": "$TC actions add action vlan modify protocol 802.1ad id 500 reclassify index 12",
         "expExitCode": "0",
         "verifyCmd": "$TC actions get action vlan index 12",
-        "matchPattern": "action order [0-9]+: vlan.*modify id 500 protocol 802.1ad priority 0 reclassify.*index 12 ref",
+        "matchPattern": "action order [0-9]+: vlan.*modify id 500 protocol 802.1ad reclassify.*index 12 ref",
         "matchCount": "1",
         "teardown": [
             "$TC actions flush action vlan"
-- 
2.29.3


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[PATCH net-next v4 3/3] net/sched: act_vlan: Test priority 0 modification

[Boris Sukholitko]

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Because explicitly being set, the priority 0 should appear
in the output.

Signed-off-by: Boris Sukholitko <boris.sukholitko@broadcom.com>
---
 .../tc-testing/tc-tests/actions/vlan.json     | 24 +++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/tools/testing/selftests/tc-testing/tc-tests/actions/vlan.json b/tools/testing/selftests/tc-testing/tc-tests/actions/vlan.json
index 1d9d261aa0b3..7467021b31ca 100644
--- a/tools/testing/selftests/tc-testing/tc-tests/actions/vlan.json
+++ b/tools/testing/selftests/tc-testing/tc-tests/actions/vlan.json
@@ -445,6 +445,30 @@
         "matchCount": "0",
         "teardown": []
     },
+    {
+        "id": "ba5b",
+        "name": "Add vlan modify action for protocol 802.1Q setting priority 0",
+        "category": [
+            "actions",
+            "vlan"
+        ],
+        "setup": [
+            [
+                "$TC actions flush action vlan",
+                0,
+                1,
+                255
+            ]
+        ],
+        "cmdUnderTest": "$TC actions add action vlan modify protocol 802.1Q id 5 priority 0 index 100",
+        "expExitCode": "0",
+        "verifyCmd": "$TC actions get action vlan index 100",
+        "matchPattern": "action order [0-9]+: vlan.*modify id 100 priority 0 protocol 802.1Q pipe.*index 100 ref",
+        "matchCount": "0",
+        "teardown": [
+            "$TC actions flush action vlan"
+        ]
+    },
     {
         "id": "6812",
         "name": "Add vlan modify action for protocol 802.1Q",
-- 
2.29.3


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[PATCH net-next v4 3/3] net/sched: act_vlan: Test priority 0 modification

[Boris Sukholitko]

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Because explicitly being set, the priority 0 should appear
in the output.

Signed-off-by: Boris Sukholitko <boris.sukholitko@broadcom.com>
---
 .../tc-testing/tc-tests/actions/vlan.json     | 24 +++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/tools/testing/selftests/tc-testing/tc-tests/actions/vlan.json b/tools/testing/selftests/tc-testing/tc-tests/actions/vlan.json
index 1d9d261aa0b3..7467021b31ca 100644
--- a/tools/testing/selftests/tc-testing/tc-tests/actions/vlan.json
+++ b/tools/testing/selftests/tc-testing/tc-tests/actions/vlan.json
@@ -445,6 +445,30 @@
         "matchCount": "0",
         "teardown": []
     },
+    {
+        "id": "ba5b",
+        "name": "Add vlan modify action for protocol 802.1Q setting priority 0",
+        "category": [
+            "actions",
+            "vlan"
+        ],
+        "setup": [
+            [
+                "$TC actions flush action vlan",
+                0,
+                1,
+                255
+            ]
+        ],
+        "cmdUnderTest": "$TC actions add action vlan modify protocol 802.1Q id 5 priority 0 index 100",
+        "expExitCode": "0",
+        "verifyCmd": "$TC actions get action vlan index 100",
+        "matchPattern": "action order [0-9]+: vlan.*modify id 100 priority 0 protocol 802.1Q pipe.*index 100 ref",
+        "matchCount": "0",
+        "teardown": [
+            "$TC actions flush action vlan"
+        ]
+    },
     {
         "id": "6812",
         "name": "Add vlan modify action for protocol 802.1Q",
-- 
2.29.3


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Re: [PATCH net-next v4 0/3] net/sched: act_vlan: Fix modify to allow 0

[Davide Caratti]

On Tue, Jun 01, 2021 at 03:30:49PM +0300, Boris Sukholitko wrote:
> Currently vlan modification action checks existence of vlan priority by
> comparing it to 0. Therefore it is impossible to modify existing vlan
> tag to have priority 0.

[...]
 
> Change Log:
> v3 -> v4:
> - revert tcf_vlan_get_fill_size change: total size calculation may race vs dump
> 
> v2 -> v3:
> - Push assumes that the priority is being set
> - tcf_vlan_get_fill_size accounts for priority existence
> 
> v1 -> v2:
> - Do not dump unset priority and fix tests accordingly
> - Test for priority 0 modification

Reviewed-by: Davide Caratti <dcaratti@redhat.com>

Re: [PATCH net-next v4 0/3] net/sched: act_vlan: Fix modify to allow 0

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net-next.git (refs/heads/master):

On Tue,  1 Jun 2021 15:30:49 +0300 you wrote:
> Currently vlan modification action checks existence of vlan priority by
> comparing it to 0. Therefore it is impossible to modify existing vlan
> tag to have priority 0.
> 
> For example, the following tc command will change the vlan id but will
> not affect vlan priority:
> 
> [...]

Here is the summary with links:
  - [net-next,v4,1/3] net/sched: act_vlan: Fix modify to allow 0
    https://git.kernel.org/netdev/net-next/c/9c5eee0afca0
  - [net-next,v4,2/3] net/sched: act_vlan: No dump for unset priority
    https://git.kernel.org/netdev/net-next/c/8323b20f1d76
  - [net-next,v4,3/3] net/sched: act_vlan: Test priority 0 modification
    https://git.kernel.org/netdev/net-next/c/8fd52b1f923c

You are awesome, thank you!
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