cgroup: add support for eBPF programs
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@zonque.org>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/bpf-cgroup.h b/include/linux/bpf-cgroup.h
new file mode 100644
index 0000000..ec80d0c
--- /dev/null
+++ b/include/linux/bpf-cgroup.h
@@ -0,0 +1,79 @@
+#ifndef _BPF_CGROUP_H
+#define _BPF_CGROUP_H
+
+#include <linux/bpf.h>
+#include <linux/jump_label.h>
+#include <uapi/linux/bpf.h>
+
+struct sock;
+struct cgroup;
+struct sk_buff;
+
+#ifdef CONFIG_CGROUP_BPF
+
+extern struct static_key_false cgroup_bpf_enabled_key;
+#define cgroup_bpf_enabled static_branch_unlikely(&cgroup_bpf_enabled_key)
+
+struct cgroup_bpf {
+ /*
+ * Store two sets of bpf_prog pointers, one for programs that are
+ * pinned directly to this cgroup, and one for those that are effective
+ * when this cgroup is accessed.
+ */
+ struct bpf_prog *prog[MAX_BPF_ATTACH_TYPE];
+ struct bpf_prog *effective[MAX_BPF_ATTACH_TYPE];
+};
+
+void cgroup_bpf_put(struct cgroup *cgrp);
+void cgroup_bpf_inherit(struct cgroup *cgrp, struct cgroup *parent);
+
+void __cgroup_bpf_update(struct cgroup *cgrp,
+ struct cgroup *parent,
+ struct bpf_prog *prog,
+ enum bpf_attach_type type);
+
+/* Wrapper for __cgroup_bpf_update() protected by cgroup_mutex */
+void cgroup_bpf_update(struct cgroup *cgrp,
+ struct bpf_prog *prog,
+ enum bpf_attach_type type);
+
+int __cgroup_bpf_run_filter(struct sock *sk,
+ struct sk_buff *skb,
+ enum bpf_attach_type type);
+
+/* Wrappers for __cgroup_bpf_run_filter() guarded by cgroup_bpf_enabled. */
+#define BPF_CGROUP_RUN_PROG_INET_INGRESS(sk,skb) \
+({ \
+ int __ret = 0; \
+ if (cgroup_bpf_enabled) \
+ __ret = __cgroup_bpf_run_filter(sk, skb, \
+ BPF_CGROUP_INET_INGRESS); \
+ \
+ __ret; \
+})
+
+#define BPF_CGROUP_RUN_PROG_INET_EGRESS(sk,skb) \
+({ \
+ int __ret = 0; \
+ if (cgroup_bpf_enabled && sk && sk == skb->sk) { \
+ typeof(sk) __sk = sk_to_full_sk(sk); \
+ if (sk_fullsock(__sk)) \
+ __ret = __cgroup_bpf_run_filter(__sk, skb, \
+ BPF_CGROUP_INET_EGRESS); \
+ } \
+ __ret; \
+})
+
+#else
+
+struct cgroup_bpf {};
+static inline void cgroup_bpf_put(struct cgroup *cgrp) {}
+static inline void cgroup_bpf_inherit(struct cgroup *cgrp,
+ struct cgroup *parent) {}
+
+#define BPF_CGROUP_RUN_PROG_INET_INGRESS(sk,skb) ({ 0; })
+#define BPF_CGROUP_RUN_PROG_INET_EGRESS(sk,skb) ({ 0; })
+
+#endif /* CONFIG_CGROUP_BPF */
+
+#endif /* _BPF_CGROUP_H */