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Date: Mon, 4 May 2015 20:48:35 +0200
From: Florian Westphal <fw@...len.de>
To: <netdev@...r.kernel.org>
Cc: jhs@...atatu.com, alexei.starovoitov@...il.com,
Florian Westphal <fw@...len.de>
Subject: [PATCH -next 2/5] net: sched: use counter to break reclassify loops
Seems all we want here is to avoid endless 'goto reclassify' loop.
tc_classify_compat even resets this counter when something other
than TC_ACT_RECLASSIFY is returned, so this skb-counter doesn't
break hypothetical loops induced by something other than perpetual
TC_ACT_RECLASSIFY return values.
skb_act_clone is now identical to skb_clone, so just use that.
Tested with following (bogus) filter:
tc filter add dev eth0 parent ffff: \
protocol ip u32 match u32 0 0 police rate 10Kbit burst \
64000 mtu 1500 action reclassify
Signed-off-by: Florian Westphal <fw@...len.de>
---
Documentation/networking/tc-actions-env-rules.txt | 4 ----
include/net/sch_generic.h | 15 ---------------
include/uapi/linux/pkt_cls.h | 4 +---
net/sched/act_mirred.c | 2 +-
net/sched/sch_api.c | 12 +++---------
5 files changed, 5 insertions(+), 32 deletions(-)
diff --git a/Documentation/networking/tc-actions-env-rules.txt b/Documentation/networking/tc-actions-env-rules.txt
index 95c7171..f378146 100644
--- a/Documentation/networking/tc-actions-env-rules.txt
+++ b/Documentation/networking/tc-actions-env-rules.txt
@@ -8,10 +8,6 @@ For example if your action queues a packet to be processed later,
or intentionally branches by redirecting a packet, then you need to
clone the packet.
-There are certain fields in the skb tc_verd that need to be reset so we
-avoid loops, etc. A few are generic enough that skb_act_clone()
-resets them for you, so invoke skb_act_clone() rather than skb_clone().
-
2) If you munge any packet thou shalt call pskb_expand_head in the case
someone else is referencing the skb. After that you "own" the skb.
diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index 994b5a0..a611ed4 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -745,21 +745,6 @@ static inline u32 qdisc_l2t(struct qdisc_rate_table* rtab, unsigned int pktlen)
return rtab->data[slot];
}
-#ifdef CONFIG_NET_CLS_ACT
-static inline struct sk_buff *skb_act_clone(struct sk_buff *skb, gfp_t gfp_mask,
- int action)
-{
- struct sk_buff *n;
-
- n = skb_clone(skb, gfp_mask);
-
- if (n) {
- n->tc_verd = SET_TC_VERD(n->tc_verd, 0);
- }
- return n;
-}
-#endif
-
struct psched_ratecfg {
u64 rate_bytes_ps; /* bytes per second */
u32 mult;
diff --git a/include/uapi/linux/pkt_cls.h b/include/uapi/linux/pkt_cls.h
index ef8eb88..02dca42 100644
--- a/include/uapi/linux/pkt_cls.h
+++ b/include/uapi/linux/pkt_cls.h
@@ -44,13 +44,13 @@ bits 9,10,11: redirect counter - redirect TTL. Loop avoidance
#define TC_OK2MUNGE _TC_MAKEMASK1(1)
#define SET_TC_OK2MUNGE(v) ( TC_OK2MUNGE | (v & ~TC_OK2MUNGE))
#define CLR_TC_OK2MUNGE(v) ( v & ~TC_OK2MUNGE)
-#endif
#define S_TC_VERD _TC_MAKE32(2)
#define M_TC_VERD _TC_MAKEMASK(4,S_TC_VERD)
#define G_TC_VERD(x) _TC_GETVALUE(x,S_TC_VERD,M_TC_VERD)
#define V_TC_VERD(x) _TC_MAKEVALUE(x,S_TC_VERD)
#define SET_TC_VERD(v,n) ((V_TC_VERD(n)) | (v & ~M_TC_VERD))
+#endif
#define S_TC_FROM _TC_MAKE32(6)
#define M_TC_FROM _TC_MAKEMASK(2,S_TC_FROM)
@@ -65,9 +65,7 @@ bits 9,10,11: redirect counter - redirect TTL. Loop avoidance
#define TC_NCLS _TC_MAKEMASK1(8)
#define SET_TC_NCLS(v) ( TC_NCLS | (v & ~TC_NCLS))
#define CLR_TC_NCLS(v) ( v & ~TC_NCLS)
-#endif
-#ifndef __KERNEL__
#define S_TC_RTTL _TC_MAKE32(9)
#define M_TC_RTTL _TC_MAKEMASK(3,S_TC_RTTL)
#define G_TC_RTTL(x) _TC_GETVALUE(x,S_TC_RTTL,M_TC_RTTL)
diff --git a/net/sched/act_mirred.c b/net/sched/act_mirred.c
index 3f63cea..a42a3b2 100644
--- a/net/sched/act_mirred.c
+++ b/net/sched/act_mirred.c
@@ -151,7 +151,7 @@ static int tcf_mirred(struct sk_buff *skb, const struct tc_action *a,
}
at = G_TC_AT(skb->tc_verd);
- skb2 = skb_act_clone(skb, GFP_ATOMIC, m->tcf_action);
+ skb2 = skb_clone(skb, GFP_ATOMIC);
if (skb2 == NULL)
goto out;
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index ad9eed7..0b74dc0 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -1816,13 +1816,8 @@ int tc_classify_compat(struct sk_buff *skb, const struct tcf_proto *tp,
continue;
err = tp->classify(skb, tp, res);
- if (err >= 0) {
-#ifdef CONFIG_NET_CLS_ACT
- if (err != TC_ACT_RECLASSIFY && skb->tc_verd)
- skb->tc_verd = SET_TC_VERD(skb->tc_verd, 0);
-#endif
+ if (err >= 0)
return err;
- }
}
return -1;
}
@@ -1834,23 +1829,22 @@ int tc_classify(struct sk_buff *skb, const struct tcf_proto *tp,
int err = 0;
#ifdef CONFIG_NET_CLS_ACT
const struct tcf_proto *otp = tp;
+ int limit = 0;
reclassify:
#endif
err = tc_classify_compat(skb, tp, res);
#ifdef CONFIG_NET_CLS_ACT
if (err == TC_ACT_RECLASSIFY) {
- u32 verd = G_TC_VERD(skb->tc_verd);
tp = otp;
- if (verd++ >= MAX_REC_LOOP) {
+ if (unlikely(limit++ >= MAX_REC_LOOP)) {
net_notice_ratelimited("%s: packet reclassify loop rule prio %u protocol %02x\n",
tp->q->ops->id,
tp->prio & 0xffff,
ntohs(tp->protocol));
return TC_ACT_SHOT;
}
- skb->tc_verd = SET_TC_VERD(skb->tc_verd, verd);
goto reclassify;
}
#endif
--
2.0.5
--
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