sk_buff: add skb extension infrastructure

[linux-2.6-block.git] / include / linux / skbuff.h

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index b1831a5ca1733932e36d44bfd78703b032a9f3e1..88f7541837e3437f3d0ef8850ccbf701ca1b1f2c 100644 (file)
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -245,6 +245,7 @@ struct iov_iter;
 struct napi_struct;
 struct bpf_prog;
 union bpf_attr;
+struct skb_ext;
 
 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 struct nf_conntrack {
@@ -636,6 +637,7 @@ typedef unsigned char *sk_buff_data_t;
  *     @queue_mapping: Queue mapping for multiqueue devices
  *     @xmit_more: More SKBs are pending for this queue
  *     @pfmemalloc: skbuff was allocated from PFMEMALLOC reserves
+ *     @active_extensions: active extensions (skb_ext_id types)
  *     @ndisc_nodetype: router type (from link layer)
  *     @ooo_okay: allow the mapping of a socket to a queue to be changed
  *     @l4_hash: indicate hash is a canonical 4-tuple hash over transport
@@ -665,6 +667,7 @@ typedef unsigned char *sk_buff_data_t;
  *     @data: Data head pointer
  *     @truesize: Buffer size
  *     @users: User count - see {datagram,tcp}.c
+ *     @extensions: allocated extensions, valid if active_extensions is nonzero
  */
 
 struct sk_buff {
@@ -747,7 +750,9 @@ struct sk_buff {
                                head_frag:1,
                                xmit_more:1,
                                pfmemalloc:1;
-
+#ifdef CONFIG_SKB_EXTENSIONS
+       __u8                    active_extensions;
+#endif
        /* fields enclosed in headers_start/headers_end are copied
         * using a single memcpy() in __copy_skb_header()
         */
@@ -869,6 +874,11 @@ struct sk_buff {
                                *data;
        unsigned int            truesize;
        refcount_t              users;
+
+#ifdef CONFIG_SKB_EXTENSIONS
+       /* only useable after checking ->active_extensions != 0 */
+       struct skb_ext          *extensions;
+#endif
 };
 
 #ifdef __KERNEL__
@@ -3896,6 +3906,105 @@ static inline void nf_conntrack_get(struct nf_conntrack *nfct)
                atomic_inc(&nfct->use);
 }
 #endif
+
+#ifdef CONFIG_SKB_EXTENSIONS
+enum skb_ext_id {
+#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
+       SKB_EXT_BRIDGE_NF,
+#endif
+       SKB_EXT_NUM, /* must be last */
+};
+
+/**
+ *     struct skb_ext - sk_buff extensions
+ *     @refcnt: 1 on allocation, deallocated on 0
+ *     @offset: offset to add to @data to obtain extension address
+ *     @chunks: size currently allocated, stored in SKB_EXT_ALIGN_SHIFT units
+ *     @data: start of extension data, variable sized
+ *
+ *     Note: offsets/lengths are stored in chunks of 8 bytes, this allows
+ *     to use 'u8' types while allowing up to 2kb worth of extension data.
+ */
+struct skb_ext {
+       refcount_t refcnt;
+       u8 offset[SKB_EXT_NUM]; /* in chunks of 8 bytes */
+       u8 chunks;              /* same */
+       char data[0] __aligned(8);
+};
+
+void *skb_ext_add(struct sk_buff *skb, enum skb_ext_id id);
+void __skb_ext_del(struct sk_buff *skb, enum skb_ext_id id);
+void __skb_ext_put(struct skb_ext *ext);
+
+static inline void skb_ext_put(struct sk_buff *skb)
+{
+       if (skb->active_extensions)
+               __skb_ext_put(skb->extensions);
+}
+
+static inline void skb_ext_get(struct sk_buff *skb)
+{
+       if (skb->active_extensions) {
+               struct skb_ext *ext = skb->extensions;
+
+               if (ext)
+                       refcount_inc(&ext->refcnt);
+       }
+}
+
+static inline void __skb_ext_copy(struct sk_buff *dst,
+                                 const struct sk_buff *src)
+{
+       dst->active_extensions = src->active_extensions;
+
+       if (src->active_extensions) {
+               struct skb_ext *ext = src->extensions;
+
+               refcount_inc(&ext->refcnt);
+               dst->extensions = ext;
+       }
+}
+
+static inline void skb_ext_copy(struct sk_buff *dst, const struct sk_buff *src)
+{
+       skb_ext_put(dst);
+       __skb_ext_copy(dst, src);
+}
+
+static inline bool __skb_ext_exist(const struct skb_ext *ext, enum skb_ext_id i)
+{
+       return !!ext->offset[i];
+}
+
+static inline bool skb_ext_exist(const struct sk_buff *skb, enum skb_ext_id id)
+{
+       return skb->active_extensions & (1 << id);
+}
+
+static inline void skb_ext_del(struct sk_buff *skb, enum skb_ext_id id)
+{
+       if (skb_ext_exist(skb, id))
+               __skb_ext_del(skb, id);
+}
+
+static inline void *skb_ext_find(const struct sk_buff *skb, enum skb_ext_id id)
+{
+       if (skb_ext_exist(skb, id)) {
+               struct skb_ext *ext = skb->extensions;
+
+               return (void *)ext + (ext->offset[id] << 3);
+       }
+
+       return NULL;
+}
+#else
+static inline void skb_ext_put(struct sk_buff *skb) {}
+static inline void skb_ext_get(struct sk_buff *skb) {}
+static inline void skb_ext_del(struct sk_buff *skb, int unused) {}
+static inline void __skb_ext_copy(struct sk_buff *d, const struct sk_buff *s) {}
+static inline void skb_ext_copy(struct sk_buff *dst, const struct sk_buff *s) {}
+#endif /* CONFIG_SKB_EXTENSIONS */
+
 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
 static inline void nf_bridge_put(struct nf_bridge_info *nf_bridge)
 {