bpf: INET_DIAG support in bpf_sk_storage

This patch adds INET_DIAG support to bpf_sk_storage.

1. Although this series adds bpf_sk_storage diag capability to inet sk,
   bpf_sk_storage is in general applicable to all fullsock.  Hence, the
   bpf_sk_storage logic will operate on SK_DIAG_* nlattr.  The caller
   will pass in its specific nesting nlattr (e.g. INET_DIAG_*) as
   the argument.

2. The request will be like:
	INET_DIAG_REQ_SK_BPF_STORAGES (nla_nest) (defined in latter patch)
		SK_DIAG_BPF_STORAGE_REQ_MAP_FD (nla_put_u32)
		SK_DIAG_BPF_STORAGE_REQ_MAP_FD (nla_put_u32)
		......

   Considering there could have multiple bpf_sk_storages in a sk,
   instead of reusing INET_DIAG_INFO ("ss -i"),  the user can select
   some specific bpf_sk_storage to dump by specifying an array of
   SK_DIAG_BPF_STORAGE_REQ_MAP_FD.

   If no SK_DIAG_BPF_STORAGE_REQ_MAP_FD is specified (i.e. an empty
   INET_DIAG_REQ_SK_BPF_STORAGES), it will dump all bpf_sk_storages
   of a sk.

3. The reply will be like:
	INET_DIAG_BPF_SK_STORAGES (nla_nest) (defined in latter patch)
		SK_DIAG_BPF_STORAGE (nla_nest)
			SK_DIAG_BPF_STORAGE_MAP_ID (nla_put_u32)
			SK_DIAG_BPF_STORAGE_MAP_VALUE (nla_reserve_64bit)
		SK_DIAG_BPF_STORAGE (nla_nest)
			SK_DIAG_BPF_STORAGE_MAP_ID (nla_put_u32)
			SK_DIAG_BPF_STORAGE_MAP_VALUE (nla_reserve_64bit)
		......

4. Unlike other INET_DIAG info of a sk which is pretty static, the size
   required to dump the bpf_sk_storage(s) of a sk is dynamic as the
   system adding more bpf_sk_storage_map.  It is hard to set a static
   min_dump_alloc size.

   Hence, this series learns it at the runtime and adjust the
   cb->min_dump_alloc as it iterates all sk(s) of a system.  The
   "unsigned int *res_diag_size" in bpf_sk_storage_diag_put()
   is for this purpose.

   The next patch will update the cb->min_dump_alloc as it
   iterates the sk(s).

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20200225230421.1975729-1-kafai@fb.com

1 files changed, 27 insertions, 0 deletions

diff --git a/include/net/bpf_sk_storage.h b/include/net/bpf_sk_storage.h
index 8e4f831d2e52..5036c94c0503 100644
--- a/include/net/bpf_sk_storage.h
+++ b/include/net/bpf_sk_storage.h
@@ -10,14 +10,41 @@ void bpf_sk_storage_free(struct sock *sk);
 extern const struct bpf_func_proto bpf_sk_storage_get_proto;
 extern const struct bpf_func_proto bpf_sk_storage_delete_proto;
 
+struct bpf_sk_storage_diag;
+struct sk_buff;
+struct nlattr;
+struct sock;
+
 #ifdef CONFIG_BPF_SYSCALL
 int bpf_sk_storage_clone(const struct sock *sk, struct sock *newsk);
+struct bpf_sk_storage_diag *
+bpf_sk_storage_diag_alloc(const struct nlattr *nla_stgs);
+void bpf_sk_storage_diag_free(struct bpf_sk_storage_diag *diag);
+int bpf_sk_storage_diag_put(struct bpf_sk_storage_diag *diag,
+			    struct sock *sk, struct sk_buff *skb,
+			    int stg_array_type,
+			    unsigned int *res_diag_size);
 #else
 static inline int bpf_sk_storage_clone(const struct sock *sk,
 				       struct sock *newsk)
 {
 	return 0;
 }
+static inline struct bpf_sk_storage_diag *
+bpf_sk_storage_diag_alloc(const struct nlattr *nla)
+{
+	return NULL;
+}
+static inline void bpf_sk_storage_diag_free(struct bpf_sk_storage_diag *diag)
+{
+}
+static inline int bpf_sk_storage_diag_put(struct bpf_sk_storage_diag *diag,
+					  struct sock *sk, struct sk_buff *skb,
+					  int stg_array_type,
+					  unsigned int *res_diag_size)
+{
+	return 0;
+}
 #endif
 
 #endif /* _BPF_SK_STORAGE_H */