diff options
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 | |
parent | f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 (diff) |
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')
-rw-r--r-- | net/core/dev.c | 6 | ||||
-rw-r--r-- | net/core/filter.c | 55 |
2 files changed, 36 insertions, 25 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); diff --git a/net/core/filter.c b/net/core/filter.c index 68adb5f52110..d11744d10e00 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -1603,9 +1603,36 @@ static const struct bpf_func_proto bpf_csum_diff_proto = { .arg5_type = ARG_ANYTHING, }; +static inline int __bpf_rx_skb(struct net_device *dev, struct sk_buff *skb) +{ + if (skb_at_tc_ingress(skb)) + skb_postpush_rcsum(skb, skb_mac_header(skb), skb->mac_len); + + return dev_forward_skb(dev, skb); +} + +static inline int __bpf_tx_skb(struct net_device *dev, struct sk_buff *skb) +{ + int ret; + + if (unlikely(__this_cpu_read(xmit_recursion) > XMIT_RECURSION_LIMIT)) { + net_crit_ratelimited("bpf: recursion limit reached on datapath, buggy bpf program?\n"); + kfree_skb(skb); + return -ENETDOWN; + } + + skb->dev = dev; + + __this_cpu_inc(xmit_recursion); + ret = dev_queue_xmit(skb); + __this_cpu_dec(xmit_recursion); + + return ret; +} + static u64 bpf_clone_redirect(u64 r1, u64 ifindex, u64 flags, u64 r4, u64 r5) { - struct sk_buff *skb = (struct sk_buff *) (long) r1, *skb2; + struct sk_buff *skb = (struct sk_buff *) (long) r1; struct net_device *dev; if (unlikely(flags & ~(BPF_F_INGRESS))) @@ -1615,19 +1642,12 @@ static u64 bpf_clone_redirect(u64 r1, u64 ifindex, u64 flags, u64 r4, u64 r5) if (unlikely(!dev)) return -EINVAL; - skb2 = skb_clone(skb, GFP_ATOMIC); - if (unlikely(!skb2)) + skb = skb_clone(skb, GFP_ATOMIC); + if (unlikely(!skb)) return -ENOMEM; - if (flags & BPF_F_INGRESS) { - if (skb_at_tc_ingress(skb2)) - skb_postpush_rcsum(skb2, skb_mac_header(skb2), - skb2->mac_len); - return dev_forward_skb(dev, skb2); - } - - skb2->dev = dev; - return dev_queue_xmit(skb2); + return flags & BPF_F_INGRESS ? + __bpf_rx_skb(dev, skb) : __bpf_tx_skb(dev, skb); } static const struct bpf_func_proto bpf_clone_redirect_proto = { @@ -1671,15 +1691,8 @@ int skb_do_redirect(struct sk_buff *skb) return -EINVAL; } - if (ri->flags & BPF_F_INGRESS) { - if (skb_at_tc_ingress(skb)) - skb_postpush_rcsum(skb, skb_mac_header(skb), - skb->mac_len); - return dev_forward_skb(dev, skb); - } - - skb->dev = dev; - return dev_queue_xmit(skb); + return ri->flags & BPF_F_INGRESS ? + __bpf_rx_skb(dev, skb) : __bpf_tx_skb(dev, skb); } static const struct bpf_func_proto bpf_redirect_proto = { |