[PATCH v6 4/6] net: filter: run cgroup eBPF ingress programs

Daniel Mack
2016-09-19T16:43:59Z

If the cgroup associated with the receiving socket has an eBPF
programs installed, run them from sk_filter_trim_cap().

eBPF programs used in this context are expected to either return 1 to
let the packet pass, or != 1 to drop them. The programs have access to
the skb through bpf_skb_load_bytes(), and the payload starts at the
network headers (L3).

Note that cgroup_bpf_run_filter() is stubbed out as static inline nop
for !CONFIG_CGROUP_BPF, and is otherwise guarded by a static key if
the feature is unused.

Signed-off-by: Daniel Mack <daniel-cYrQPVfZoowdnm+yROfE0A@public.gmane.org>
---
net/core/filter.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/net/core/filter.c b/net/core/filter.c
index e46c98e..ce6e527 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -78,6 +78,10 @@ int sk_filter_trim_cap(struct sock *sk, struct sk_buff *skb, unsigned int cap)
if (skb_pfmemalloc(skb) && !sock_flag(sk, SOCK_MEMALLOC))
return -ENOMEM;

+ err = cgroup_bpf_run_filter(sk, skb, BPF_CGROUP_INET_INGRESS);
+ if (err)
+ return err;
+
err = security_sock_rcv_skb(sk, skb);
if (err)
return err;
--
2.5.5