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authorDaniel Borkmann <daniel@iogearbox.net>2016-06-10 21:19:06 +0200
committerDavid S. Miller <davem@davemloft.net>2016-06-10 18:00:57 -0700
commita70b506efe899dc8d650eafcc0b11fc9ee746627 (patch)
treee938bd0ddcc06c32df59b527d148ffa7aab9f636 /net/core/dev.c
parentf2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 (diff)
downloadop-kernel-dev-a70b506efe899dc8d650eafcc0b11fc9ee746627.zip
op-kernel-dev-a70b506efe899dc8d650eafcc0b11fc9ee746627.tar.gz
bpf: enforce recursion limit on redirects
Respect the stack's xmit_recursion limit for calls into dev_queue_xmit(). Currently, they are not handeled by the limiter when attached to clsact's egress parent, for example, and a buggy program redirecting it to the same device again could run into stack overflow eventually. It would be good if we could notify an admin to give him a chance to react. We reuse xmit_recursion instead of having one private to eBPF, so that the stack's current recursion depth will be taken into account as well. Follow-up to commit 3896d655f4d4 ("bpf: introduce bpf_clone_redirect() helper") and 27b29f63058d ("bpf: add bpf_redirect() helper"). Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core/dev.c')
-rw-r--r--net/core/dev.c6
1 files changed, 2 insertions, 4 deletions
diff --git a/net/core/dev.c b/net/core/dev.c
index c43c9d2..b148357 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3144,8 +3144,6 @@ static void skb_update_prio(struct sk_buff *skb)
DEFINE_PER_CPU(int, xmit_recursion);
EXPORT_SYMBOL(xmit_recursion);
-#define RECURSION_LIMIT 10
-
/**
* dev_loopback_xmit - loop back @skb
* @net: network namespace this loopback is happening in
@@ -3388,8 +3386,8 @@ static int __dev_queue_xmit(struct sk_buff *skb, void *accel_priv)
int cpu = smp_processor_id(); /* ok because BHs are off */
if (txq->xmit_lock_owner != cpu) {
-
- if (__this_cpu_read(xmit_recursion) > RECURSION_LIMIT)
+ if (unlikely(__this_cpu_read(xmit_recursion) >
+ XMIT_RECURSION_LIMIT))
goto recursion_alert;
skb = validate_xmit_skb(skb, dev);
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