[PATCH v2 bpf-next 03/14] bpf: pass a pointer to a cgroup storage using pcpu variable

Roman Gushchin
2018-07-05T20:57:05Z

This commit introduces the bpf_cgroup_storage_set() helper,
which will be used to pass a pointer to a cgroup storage
to the bpf helper.

Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
---
include/linux/bpf-cgroup.h | 15 +++++++++++++++
kernel/bpf/local_storage.c | 2 ++
2 files changed, 17 insertions(+)

diff --git a/include/linux/bpf-cgroup.h b/include/linux/bpf-cgroup.h
index 6b0e7bd4b154..ce77a6dffb6d 100644
--- a/include/linux/bpf-cgroup.h
+++ b/include/linux/bpf-cgroup.h
@@ -3,6 +3,7 @@
#define _BPF_CGROUP_H

#include <linux/jump_label.h>
+#include <linux/percpu-defs.h>
#include <linux/rbtree.h>
#include <uapi/linux/bpf.h>

@@ -20,6 +21,8 @@ struct bpf_cgroup_storage;
extern struct static_key_false cgroup_bpf_enabled_key;
#define cgroup_bpf_enabled static_branch_unlikely(&cgroup_bpf_enabled_key)

+DECLARE_PER_CPU(void*, bpf_cgroup_storage);
+
struct bpf_cgroup_storage_map;

struct bpf_storage_buffer {
@@ -96,6 +99,17 @@ int __cgroup_bpf_run_filter_sock_ops(struct sock *sk,
int __cgroup_bpf_check_dev_permission(short dev_type, u32 major, u32 minor,
short access, enum bpf_attach_type type);

+static inline void bpf_cgroup_storage_set(struct bpf_cgroup_storage *storage)
+{
+ struct bpf_storage_buffer *buf;
+
+ if (!storage)
+ return;
+
+ buf = rcu_dereference(storage->buf);
+ this_cpu_write(bpf_cgroup_storage, &buf->data[0]);
+}
+
struct bpf_cgroup_storage *bpf_cgroup_storage_alloc(struct bpf_prog *prog);
void bpf_cgroup_storage_free(struct bpf_cgroup_storage *storage);
void bpf_cgroup_storage_link(struct bpf_cgroup_storage *storage,
@@ -249,6 +263,7 @@ static inline int cgroup_bpf_prog_query(const union bpf_attr *attr,
return -EINVAL;
}

+static inline void bpf_cgroup_storage_set(struct bpf_cgroup_storage *storage) {}
static inline int bpf_cgroup_storage_assign(struct bpf_prog *prog,
struct bpf_map *map) { return 0; }
static inline void bpf_cgroup_storage_release(struct bpf_prog *prog,
diff --git a/kernel/bpf/local_storage.c b/kernel/bpf/local_storage.c
index 940889eda2c7..38810a712971 100644
--- a/kernel/bpf/local_storage.c
+++ b/kernel/bpf/local_storage.c
@@ -7,6 +7,8 @@
#include <linux/rbtree.h>
#include <linux/slab.h>

+DEFINE_PER_CPU(void*, bpf_cgroup_storage);
+
#ifdef CONFIG_CGROUP_BPF

struct bpf_cgroup_storage_map {
--
2.14.4