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authorDavide Caratti <dcaratti@redhat.com>2019-10-12 13:55:07 +0200
committerDavid S. Miller <davem@davemloft.net>2019-10-15 17:14:48 -0700
commitfa4e0f8855fcba600e0be2575ee29c69166f74bd (patch)
tree3224a12d0c83472a92df41f3dfff6c48b6fd1f64 /net/sched
parentdedc5a08da07874c6e0d411e7f39c5c2cf137014 (diff)
downloadlinux-fa4e0f8855fcba600e0be2575ee29c69166f74bd.tar.bz2
net/sched: fix corrupted L2 header with MPLS 'push' and 'pop' actions
the following script: # tc qdisc add dev eth0 clsact # tc filter add dev eth0 egress protocol ip matchall \ > action mpls push protocol mpls_uc label 0x355aa bos 1 causes corruption of all IP packets transmitted by eth0. On TC egress, we can't rely on the value of skb->mac_len, because it's 0 and a MPLS 'push' operation will result in an overwrite of the first 4 octets in the packet L2 header (e.g. the Destination Address if eth0 is an Ethernet); the same error pattern is present also in the MPLS 'pop' operation. Fix this error in act_mpls data plane, computing 'mac_len' as the difference between the network header and the mac header (when not at TC ingress), and use it in MPLS 'push'/'pop' core functions. v2: unbreak 'make htmldocs' because of missing documentation of 'mac_len' in skb_mpls_pop(), reported by kbuild test robot CC: Lorenzo Bianconi <lorenzo@kernel.org> Fixes: 2a2ea50870ba ("net: sched: add mpls manipulation actions to TC") Reviewed-by: Simon Horman <simon.horman@netronome.com> Acked-by: John Hurley <john.hurley@netronome.com> Signed-off-by: Davide Caratti <dcaratti@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/sched')
-rw-r--r--net/sched/act_mpls.c12
1 files changed, 8 insertions, 4 deletions
diff --git a/net/sched/act_mpls.c b/net/sched/act_mpls.c
index e168df0e008a..4cf6c553bb0b 100644
--- a/net/sched/act_mpls.c
+++ b/net/sched/act_mpls.c
@@ -55,7 +55,7 @@ static int tcf_mpls_act(struct sk_buff *skb, const struct tc_action *a,
struct tcf_mpls *m = to_mpls(a);
struct tcf_mpls_params *p;
__be32 new_lse;
- int ret;
+ int ret, mac_len;
tcf_lastuse_update(&m->tcf_tm);
bstats_cpu_update(this_cpu_ptr(m->common.cpu_bstats), skb);
@@ -63,8 +63,12 @@ static int tcf_mpls_act(struct sk_buff *skb, const struct tc_action *a,
/* Ensure 'data' points at mac_header prior calling mpls manipulating
* functions.
*/
- if (skb_at_tc_ingress(skb))
+ if (skb_at_tc_ingress(skb)) {
skb_push_rcsum(skb, skb->mac_len);
+ mac_len = skb->mac_len;
+ } else {
+ mac_len = skb_network_header(skb) - skb_mac_header(skb);
+ }
ret = READ_ONCE(m->tcf_action);
@@ -72,12 +76,12 @@ static int tcf_mpls_act(struct sk_buff *skb, const struct tc_action *a,
switch (p->tcfm_action) {
case TCA_MPLS_ACT_POP:
- if (skb_mpls_pop(skb, p->tcfm_proto))
+ if (skb_mpls_pop(skb, p->tcfm_proto, mac_len))
goto drop;
break;
case TCA_MPLS_ACT_PUSH:
new_lse = tcf_mpls_get_lse(NULL, p, !eth_p_mpls(skb->protocol));
- if (skb_mpls_push(skb, new_lse, p->tcfm_proto))
+ if (skb_mpls_push(skb, new_lse, p->tcfm_proto, mac_len))
goto drop;
break;
case TCA_MPLS_ACT_MODIFY: