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| author | Daniel Borkmann <daniel@iogearbox.net> | 2016-06-10 21:19:06 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2016-06-10 18:00:57 -0700 |
| commit | a70b506efe899dc8d650eafcc0b11fc9ee746627 (patch) | |
| tree | e938bd0ddcc06c32df59b527d148ffa7aab9f636 /net/core/dev.c | |
| parent | f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 (diff) | |
| download | lwn-a70b506efe899dc8d650eafcc0b11fc9ee746627.tar.gz lwn-a70b506efe899dc8d650eafcc0b11fc9ee746627.zip | |
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.c | 6 |
1 files changed, 2 insertions, 4 deletions
diff --git a/net/core/dev.c b/net/core/dev.c index c43c9d2a88cf..b14835757141 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); |