Re: [PATCH v3 4/6] net: filter: run cgroup eBPF ingress programs

[Daniel Borkmann]

On 08/26/2016 09:58 PM, Daniel Mack wrote:

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 full skb, including the MAC headers.

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 
---
  net/core/filter.c | 5 +
  1 file changed, 5 insertions(+)

diff --git a/net/core/filter.c b/net/core/filter.c
index bc04e5c..163f75b 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -78,6 +78,11 @@ 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_ATTACH_TYPE_CGROUP_INET_INGRESS);


Maybe just BPF_CGROUP_INET_{IN,E}GRESS (seems less cluttered, and we know
these were set via bpf(2) as attach_type anyway)?


+   if (err)
+   return err;
+
err = security_sock_rcv_skb(sk, skb);
if (err)
return err;

[PATCH v3 4/6] net: filter: run cgroup eBPF ingress programs

[Daniel Mack]

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 full skb, including the MAC headers.

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 
---
 net/core/filter.c | 5 +
 1 file changed, 5 insertions(+)

diff --git a/net/core/filter.c b/net/core/filter.c
index bc04e5c..163f75b 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -78,6 +78,11 @@ 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_ATTACH_TYPE_CGROUP_INET_INGRESS);
+   if (err)
+   return err;
+
err = security_sock_rcv_skb(sk, skb);
if (err)
return err;
-- 
2.5.5