On 09/06/2016 03:46 PM, Daniel Mack wrote:
This patch adds two sets of eBPF program pointers to struct cgroup.
One for such that are directly pinned to a cgroup, and one for such
that are effective for it.
To illustrate the logic behind that, assume the following example
cgroup hierarchy.
A - B - C
\ D - E
If only B has a program attached, it will be effective for B, C, D
and E. If D then attaches a program itself, that will be effective for
both D and E, and the program in B will only affect B and C. Only one
program of a given type is effective for a cgroup.
Attaching and detaching programs will be done through the bpf(2)
syscall. For now, ingress and egress inet socket filtering are the
only supported use-cases.
Signed-off-by: Daniel Mack <daniel@xxxxxxxxxx>
[...]
+/**
+ * __cgroup_bpf_run_filter() - Run a program for packet filtering
+ * @sk: The socken sending or receiving traffic
+ * @skb: The skb that is being sent or received
+ * @type: The type of program to be exectuted
+ *
+ * If no socket is passed, or the socket is not of type INET or INET6,
+ * this function does nothing and returns 0.
+ *
+ * The program type passed in via @type must be suitable for network
+ * filtering. No further check is performed to assert that.
+ *
+ * This function will return %-EPERM if any if an attached program was found
+ * and if it returned != 1 during execution. In all other cases, 0 is returned.
+ */
+int __cgroup_bpf_run_filter(struct sock *sk,
+ struct sk_buff *skb,
+ enum bpf_attach_type type)
+{
+ struct bpf_prog *prog;
+ struct cgroup *cgrp;
+ int ret = 0;
+
+ if (!sk)
+ return 0;
Doesn't this also need to check || !sk_fullsock(sk)?
+
+ if (sk->sk_family != AF_INET &&
+ sk->sk_family != AF_INET6)
+ return 0;
+
+ cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
+
+ rcu_read_lock();
+
+ prog = rcu_dereference(cgrp->bpf.effective[type]);
+ if (prog) {
+ unsigned int offset = skb->data - skb_mac_header(skb);
+
+ __skb_push(skb, offset);
+ ret = bpf_prog_run_clear_cb(prog, skb) == 1 ? 0 : -EPERM;
+ __skb_pull(skb, offset);
+ }
+
+ rcu_read_unlock();
+
+ return ret;
+}
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