[PATCH v4 bpf-next 03/14] bpf: pass a pointer to a cgroup storage using pcpu variable

From: Roman Gushchin
Date: Fri Jul 27 2018 - 17:53:32 EST


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@xxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Acked-by: Martin KaFai Lau <kafai@xxxxxx>
---
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 7d00d58869ed..9a144ddbbc8f 100644
--- a/include/linux/bpf-cgroup.h
+++ b/include/linux/bpf-cgroup.h
@@ -4,6 +4,7 @@

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

@@ -21,6 +22,8 @@ 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 {
@@ -97,6 +100,17 @@ 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 = READ_ONCE(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,
@@ -250,6 +264,7 @@ 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 395e7278ec75..62feded85e6b 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