skbedit: allow the user to specify bitmask for mark

From: Antonio Quartulli <[email protected]>

The user may want to use only some bits of the skb mark in his skbedit rules because the remaining part might be used by something else.

Introduce the "mask" parameter to the skbedit actor in order to implement such functionality.

When the mask is specified, only those bits selected by the latter are altered really changed by the actor, while the rest is left untouched.

Cc Jamal Hadi Salim <[email protected]>

Signed-off-by Antonio Quartulli <[email protected]>

---

Jamal, I'm not adding your Signed-off because the patches has new part with respect to v1.

net/sched/act_skbedit.c +1 -0

+		goto nla_put_failure;
 	t.install = jiffies_to_clock_t(jiffies - d->tcf_tm.install);
 	t.lastuse = jiffies_to_clock_t(jiffies - d->tcf_tm.lastuse);
 	t.expires = jiffies_to_clock_t(d->tcf_tm.expires);

From: Antonio Quartulli <[email protected]>

The user may want to use only some bits of the skb mark in his skbedit rules because the remaining part might be used by something else.

Introduce the "mask" parameter to the skbedit actor in order to implement such functionality.

When the mask is specified, only those bits selected by the latter are altered really changed by the actor, while the rest is left untouched.

Cc Jamal Hadi Salim <[email protected]>

Signed-off-by Antonio Quartulli <[email protected]>

---

Jamal, I'm not adding your Signed-off because the patches has new part with respect to v1.

Changes from v1:
- use '&=' tcf_skbedit() to clean the mark
- extend tcf_skbedit_dump() in order to send the mask as well

 include/net/tc_act/tc_skbedit.h        |  1 +
 include/uapi/linux/tc_act/tc_skbedit.h |  2 ++
 net/sched/act_skbedit.c                | 24 +++++++++++++++++++++---
 3 files changed, 24 insertions(+), 3 deletions(-)

include/net/tc_act/tc_skbedit.h +1 -0

index 0df9a0d..a385c68 100644
@@ -26,6 +26,7 @@ struct tcf_skbedit {
        u32                     flags;
        u32                     priority;
        u32                     mark;
+       u32                     mask;
        u16                     queue_mapping;
        /* XXX: 16-bit pad here? */
 };

include/uapi/linux/tc_act/tc_skbedit.h +2 -0

index 7a2e910..c7c8c5f 100644
@@ -27,6 +27,7 @@
 #define SKBEDIT_F_PRIORITY             0x1
 #define SKBEDIT_F_QUEUE_MAPPING                0x2
 #define SKBEDIT_F_MARK                 0x4
+#define SKBEDIT_F_MASK                 0x8
 
 struct tc_skbedit {
        tc_gen;

@@ -39,6 +40,7 @@ enum {
        TCA_SKBEDIT_PRIORITY,
        TCA_SKBEDIT_QUEUE_MAPPING,
        TCA_SKBEDIT_MARK,
+       TCA_SKBEDIT_MASK,
        __TCA_SKBEDIT_MAX
 };
 #define TCA_SKBEDIT_MAX (__TCA_SKBEDIT_MAX - 1)

net/sched/act_skbedit.c +21 -4

index fcfeeaf..6111b06 100644
@@ -43,8 +43,12 @@ static int tcf_skbedit(struct sk_buff *skb, const struct tc_action *a,
        if (d->flags & SKBEDIT_F_QUEUE_MAPPING &&
            skb->dev->real_num_tx_queues > d->queue_mapping)
                skb_set_queue_mapping(skb, d->queue_mapping);
-       if (d->flags & SKBEDIT_F_MARK)
-               skb->mark = d->mark;
+       if (d->flags & SKBEDIT_F_MARK) {
+               /* unset all the bits in the mask */
+               skb->mark &= ~d->mask;
+               /* assign the mark value for the masked bit only */
+               skb->mark |= d->mark & d->mask;
+       }
 
        spin_unlock(&d->tcf_lock);
        return d->tcf_action;

@@ -55,6 +59,7 @@ static const struct nla_policy skbedit_policy[TCA_SKBEDIT_MAX + 1] = {
        [TCA_SKBEDIT_PRIORITY]          = { .len = sizeof(u32) },
        [TCA_SKBEDIT_QUEUE_MAPPING]     = { .len = sizeof(u16) },
        [TCA_SKBEDIT_MARK]              = { .len = sizeof(u32) },
+       [TCA_SKBEDIT_MASK]              = { .len = sizeof(u32) },
 };
 
 static int tcf_skbedit_init(struct net *net, struct nlattr *nla,

@@ -64,7 +69,7 @@ static int tcf_skbedit_init(struct net *net, struct nlattr *nla,
        struct nlattr *tb[TCA_SKBEDIT_MAX + 1];
        struct tc_skbedit *parm;
        struct tcf_skbedit *d;
-       u32 flags = 0, *priority = NULL, *mark = NULL;
+       u32 flags = 0, *priority = NULL, *mark = NULL, *mask = NULL;
        u16 *queue_mapping = NULL;
        int ret = 0, err;
 

@@ -93,6 +98,11 @@ static int tcf_skbedit_init(struct net *net, struct nlattr *nla,
                mark = nla_data(tb[TCA_SKBEDIT_MARK]);
        }
 
+       if (tb[TCA_SKBEDIT_MASK] != NULL) {
+               flags |= SKBEDIT_F_MASK;
+               mask = nla_data(tb[TCA_SKBEDIT_MASK]);
+       }
+
        if (!flags)
                return -EINVAL;
 

@@ -123,6 +133,10 @@ static int tcf_skbedit_init(struct net *net, struct nlattr *nla,
                d->queue_mapping = *queue_mapping;
        if (flags & SKBEDIT_F_MARK)
                d->mark = *mark;
+       /* default behaviour is to use all the bits */
+       d->mask = 0xffffffff;
+       if (flags & SKBEDIT_F_MASK)
+               d->mask = *mask;
 
        d->tcf_action = parm->action;
 

@@ -160,6 +174,10 @@ static int tcf_skbedit_dump(struct sk_buff *skb, struct tc_action *a,
            nla_put(skb, TCA_SKBEDIT_MARK, sizeof(d->mark),
                    &d->mark))
                goto nla_put_failure;
+       if ((d->flags & SKBEDIT_F_MASK) &&
+           nla_put(skb, TCA_SKBEDIT_MASK, sizeof(d->mask),
+                   &d->mark))
+               goto nla_put_failure;
        t.install = jiffies_to_clock_t(jiffies - d->tcf_tm.install);
        t.lastuse = jiffies_to_clock_t(jiffies - d->tcf_tm.lastuse);
        t.expires = jiffies_to_clock_t(d->tcf_tm.expires);
--

1.8.5.5

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#define TCA_SKBEDIT_MAX (__TCA_SKBEDIT_MAX - 1)

net/sched/act_skbedit.c +0 -0

index fcfeeaf..6111b06 100644