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Message-Id: <1461257907-4458-2-git-send-email-nicolas.dichtel@6wind.com>
Date: Thu, 21 Apr 2016 18:58:24 +0200
From: Nicolas Dichtel <nicolas.dichtel@...nd.com>
To: netdev@...r.kernel.org
Cc: davem@...emloft.net, roopa@...ulusnetworks.com,
eric.dumazet@...il.com, tgraf@...g.ch, jhs@...atatu.com,
Nicolas Dichtel <nicolas.dichtel@...nd.com>
Subject: [PATCH net-next v2 1/4] libnl: add more helpers to align attributes on 64-bit
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@...nd.com>
---
include/net/netlink.h | 39 +++++++++++++++-----
lib/nlattr.c | 99 +++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 130 insertions(+), 8 deletions(-)
diff --git a/include/net/netlink.h b/include/net/netlink.h
index 3c1fd92a52c8..6f51a8a06498 100644
--- a/include/net/netlink.h
+++ b/include/net/netlink.h
@@ -244,13 +244,21 @@ int nla_memcpy(void *dest, const struct nlattr *src, int count);
int nla_memcmp(const struct nlattr *nla, const void *data, size_t size);
int nla_strcmp(const struct nlattr *nla, const char *str);
struct nlattr *__nla_reserve(struct sk_buff *skb, int attrtype, int attrlen);
+struct nlattr *__nla_reserve_64bit(struct sk_buff *skb, int attrtype,
+ int attrlen, int padattr);
void *__nla_reserve_nohdr(struct sk_buff *skb, int attrlen);
struct nlattr *nla_reserve(struct sk_buff *skb, int attrtype, int attrlen);
+struct nlattr *nla_reserve_64bit(struct sk_buff *skb, int attrtype,
+ int attrlen, int padattr);
void *nla_reserve_nohdr(struct sk_buff *skb, int attrlen);
void __nla_put(struct sk_buff *skb, int attrtype, int attrlen,
const void *data);
+void __nla_put_64bit(struct sk_buff *skb, int attrtype, int attrlen,
+ const void *data, int padattr);
void __nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data);
int nla_put(struct sk_buff *skb, int attrtype, int attrlen, const void *data);
+int nla_put_64bit(struct sk_buff *skb, int attrtype, int attrlen,
+ const void *data, int padattr);
int nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data);
int nla_append(struct sk_buff *skb, int attrlen, const void *data);
@@ -1231,6 +1239,27 @@ static inline int nla_validate_nested(const struct nlattr *start, int maxtype,
}
/**
+ * 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
@@ -1244,16 +1273,10 @@ static inline int nla_validate_nested(const struct nlattr *start, int maxtype,
*/
static inline int nla_align_64bit(struct sk_buff *skb, int padattr)
{
-#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. This 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) &&
+ if (nla_need_padding_for_64bit(skb) &&
!nla_reserve(skb, padattr, 0))
return -EMSGSIZE;
-#endif
+
return 0;
}
diff --git a/lib/nlattr.c b/lib/nlattr.c
index f5907d23272d..2b82f1e2ebc2 100644
--- a/lib/nlattr.c
+++ b/lib/nlattr.c
@@ -355,6 +355,29 @@ struct nlattr *__nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
EXPORT_SYMBOL(__nla_reserve);
/**
+ * __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
+ *
+ * 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 be 64-bit aign.
+ *
+ * The caller is responsible to ensure that the skb provides enough
+ * tailroom for the attribute header and payload.
+ */
+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);
+}
+EXPORT_SYMBOL(__nla_reserve_64bit);
+
+/**
* __nla_reserve_nohdr - reserve room for attribute without header
* @skb: socket buffer to reserve room on
* @attrlen: length of attribute payload
@@ -397,6 +420,35 @@ struct nlattr *nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
EXPORT_SYMBOL(nla_reserve);
/**
+ * 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
+ *
+ * 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 be 64-bit aign.
+ *
+ * Returns NULL if the tailroom of the skb is insufficient to store
+ * the attribute header and payload.
+ */
+struct nlattr *nla_reserve_64bit(struct sk_buff *skb, int attrtype, int attrlen,
+ 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 NULL;
+
+ return __nla_reserve_64bit(skb, attrtype, attrlen, padattr);
+}
+EXPORT_SYMBOL(nla_reserve_64bit);
+
+/**
* nla_reserve_nohdr - reserve room for attribute without header
* @skb: socket buffer to reserve room on
* @attrlen: length of attribute payload
@@ -436,6 +488,26 @@ void __nla_put(struct sk_buff *skb, int attrtype, int attrlen,
EXPORT_SYMBOL(__nla_put);
/**
+ * __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
+ *
+ * The caller is responsible to ensure that the skb provides enough
+ * tailroom for the attribute header and payload.
+ */
+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);
+}
+EXPORT_SYMBOL(__nla_put_64bit);
+
+/**
* __nla_put_nohdr - Add a netlink attribute without header
* @skb: socket buffer to add attribute to
* @attrlen: length of attribute payload
@@ -474,6 +546,33 @@ int nla_put(struct sk_buff *skb, int attrtype, int attrlen, const void *data)
EXPORT_SYMBOL(nla_put);
/**
+ * 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
+ *
+ * Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
+ * the attribute header and payload.
+ */
+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;
+}
+EXPORT_SYMBOL(nla_put_64bit);
+
+/**
* nla_put_nohdr - Add a netlink attribute without header
* @skb: socket buffer to add attribute to
* @attrlen: length of attribute payload
--
2.4.2
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