From: Felix Fietkau <nbd@nbd.name>
Date: Sat, 14 May 2016 16:40:16 +0200
Subject: [PATCH] header: backport nla_put_u64_64bit and nla_put_64bit

Signed-off-by: Felix Fietkau <nbd@nbd.name>
---

--- a/backport-include/net/netlink.h
+++ b/backport-include/net/netlink.h
@@ -189,4 +189,148 @@ static inline __le64 nla_get_le64(const
 }
 #endif /* < 4.4 */
 
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(4,7,0)
+
+/**
+ * nla_need_padding_for_64bit - test 64-bit alignment of the next attribute
+ * @skb: socket buffer the message is stored in
+ *
+ * Return true if padding is needed to align the next attribute (nla_data()) to
+ * a 64-bit aligned area.
+ */
+static inline bool nla_need_padding_for_64bit(struct sk_buff *skb)
+{
+#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
+	/* The nlattr header is 4 bytes in size, that's why we test
+	 * if the skb->data _is_ aligned.  A NOP attribute, plus
+	 * nlattr header for next attribute, will make nla_data()
+	 * 8-byte aligned.
+	 */
+	if (IS_ALIGNED((unsigned long)skb_tail_pointer(skb), 8))
+		return true;
+#endif
+	return false;
+}
+
+/**
+ * nla_align_64bit - 64-bit align the nla_data() of next attribute
+ * @skb: socket buffer the message is stored in
+ * @padattr: attribute type for the padding
+ *
+ * Conditionally emit a padding netlink attribute in order to make
+ * the next attribute we emit have a 64-bit aligned nla_data() area.
+ * This will only be done in architectures which do not have
+ * CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS defined.
+ *
+ * Returns zero on success or a negative error code.
+ */
+static inline int nla_align_64bit(struct sk_buff *skb, int padattr)
+{
+	if (nla_need_padding_for_64bit(skb) &&
+	    !nla_reserve(skb, padattr, 0))
+		return -EMSGSIZE;
+
+	return 0;
+}
+
+/**
+ * __nla_reserve_64bit - reserve room for attribute on the skb and align it
+ * @skb: socket buffer to reserve room on
+ * @attrtype: attribute type
+ * @attrlen: length of attribute payload
+ * @padattr: attribute type for the padding
+ *
+ * Adds a netlink attribute header to a socket buffer and reserves
+ * room for the payload but does not copy it. It also ensure that this
+ * attribute will have a 64-bit aligned nla_data() area.
+ *
+ * The caller is responsible to ensure that the skb provides enough
+ * tailroom for the attribute header and payload.
+ */
+static inline struct nlattr *__nla_reserve_64bit(struct sk_buff *skb, int attrtype,
+						 int attrlen, int padattr)
+{
+	if (nla_need_padding_for_64bit(skb))
+		nla_align_64bit(skb, padattr);
+
+	return __nla_reserve(skb, attrtype, attrlen);
+}
+
+/**
+ * __nla_put_64bit - Add a netlink attribute to a socket buffer and align it
+ * @skb: socket buffer to add attribute to
+ * @attrtype: attribute type
+ * @attrlen: length of attribute payload
+ * @data: head of attribute payload
+ * @padattr: attribute type for the padding
+ *
+ * The caller is responsible to ensure that the skb provides enough
+ * tailroom for the attribute header and payload.
+ */
+static inline void __nla_put_64bit(struct sk_buff *skb, int attrtype, int attrlen,
+				   const void *data, int padattr)
+{
+	struct nlattr *nla;
+
+	nla = __nla_reserve_64bit(skb, attrtype, attrlen, padattr);
+	memcpy(nla_data(nla), data, attrlen);
+}
+
+/**
+ * nla_total_size_64bit - total length of attribute including padding
+ * @payload: length of payload
+ */
+static inline int nla_total_size_64bit(int payload)
+{
+	return NLA_ALIGN(nla_attr_size(payload))
+#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
+		+ NLA_ALIGN(nla_attr_size(0))
+#endif
+		;
+}
+
+/**
+ * nla_put_64bit - Add a netlink attribute to a socket buffer and align it
+ * @skb: socket buffer to add attribute to
+ * @attrtype: attribute type
+ * @attrlen: length of attribute payload
+ * @data: head of attribute payload
+ * @padattr: attribute type for the padding
+ *
+ * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
+ * the attribute header and payload.
+ */
+static inline int nla_put_64bit(struct sk_buff *skb, int attrtype, int attrlen,
+				const void *data, int padattr)
+{
+	size_t len;
+
+	if (nla_need_padding_for_64bit(skb))
+		len = nla_total_size_64bit(attrlen);
+	else
+		len = nla_total_size(attrlen);
+	if (unlikely(skb_tailroom(skb) < len))
+		return -EMSGSIZE;
+
+	__nla_put_64bit(skb, attrtype, attrlen, data, padattr);
+	return 0;
+}
+
+/**
+ * nla_put_u64_64bit - Add a u64 netlink attribute to a skb and align it
+ * @skb: socket buffer to add attribute to
+ * @attrtype: attribute type
+ * @value: numeric value
+ * @padattr: attribute type for the padding
+ */
+static inline int nla_put_u64_64bit(struct sk_buff *skb, int attrtype,
+				    u64 value, int padattr)
+{
+	return nla_put_64bit(skb, attrtype, sizeof(u64), &value, padattr);
+}
+
+
+#endif /* LINUX_VERSION_CODE < KERNEL_VERSION(4,7,0) */
+
 #endif /* __BACKPORT_NET_NETLINK_H */