net: filter: run cgroup eBPF ingress programs

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@zonque.org>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/core/filter.c b/net/core/filter.c
index 2de302d..ea315af 100644 (file)
--- 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 = BPF_CGROUP_RUN_PROG_INET_INGRESS(sk, skb);
+       if (err)
+               return err;
+
        err = security_sock_rcv_skb(sk, skb);
        if (err)
                return err;