[NETLINK]: Extend netlink messaging interface
Adds:
nlmsg_get_pos() return current position in message
nlmsg_trim() trim part of message
nla_reserve_nohdr(skb, len) reserve room for an attribute w/o hdr
nla_put_nohdr(skb, len, data) add attribute w/o hdr
nla_find_nested() find attribute in nested attributes
Fixes nlmsg_new() to take allocation flags and consider size.
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/netlink.h b/include/net/netlink.h
index 640c26a..3a5e40b 100644
--- a/include/net/netlink.h
+++ b/include/net/netlink.h
@@ -35,6 +35,8 @@
* nlmsg_put() add a netlink message to an skb
* nlmsg_put_answer() callback based nlmsg_put()
* nlmsg_end() finanlize netlink message
+ * nlmsg_get_pos() return current position in message
+ * nlmsg_trim() trim part of message
* nlmsg_cancel() cancel message construction
* nlmsg_free() free a netlink message
*
@@ -80,8 +82,10 @@
* struct nlattr netlink attribtue header
*
* Attribute Construction:
- * nla_reserve(skb, type, len) reserve skb tailroom for an attribute
+ * nla_reserve(skb, type, len) reserve room for an attribute
+ * nla_reserve_nohdr(skb, len) reserve room for an attribute w/o hdr
* nla_put(skb, type, len, data) add attribute to skb
+ * nla_put_nohdr(skb, len, data) add attribute w/o hdr
*
* Attribute Construction for Basic Types:
* nla_put_u8(skb, type, value) add u8 attribute to skb
@@ -139,6 +143,7 @@
* nla_next(nla, remaining) get next netlink attribute
* nla_validate() validate a stream of attributes
* nla_find() find attribute in stream of attributes
+ * nla_find_nested() find attribute in nested attributes
* nla_parse() parse and validate stream of attrs
* nla_parse_nested() parse nested attribuets
* nla_for_each_attr() loop over all attributes
@@ -203,12 +208,18 @@
extern int nla_strcmp(const struct nlattr *nla, const char *str);
extern struct nlattr * __nla_reserve(struct sk_buff *skb, int attrtype,
int attrlen);
+extern void * __nla_reserve_nohdr(struct sk_buff *skb, int attrlen);
extern struct nlattr * nla_reserve(struct sk_buff *skb, int attrtype,
int attrlen);
+extern void * nla_reserve_nohdr(struct sk_buff *skb, int attrlen);
extern void __nla_put(struct sk_buff *skb, int attrtype,
int attrlen, const void *data);
+extern void __nla_put_nohdr(struct sk_buff *skb, int attrlen,
+ const void *data);
extern int nla_put(struct sk_buff *skb, int attrtype,
int attrlen, const void *data);
+extern int nla_put_nohdr(struct sk_buff *skb, int attrlen,
+ const void *data);
/**************************************************************************
* Netlink Messages
@@ -453,12 +464,13 @@
/**
* nlmsg_new - Allocate a new netlink message
* @size: maximum size of message
+ * @flags: the type of memory to allocate.
*
* Use NLMSG_GOODSIZE if size isn't know and you need a good default size.
*/
-static inline struct sk_buff *nlmsg_new(int size)
+static inline struct sk_buff *nlmsg_new(int size, gfp_t flags)
{
- return alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
+ return alloc_skb(size, flags);
}
/**
@@ -480,6 +492,32 @@
}
/**
+ * nlmsg_get_pos - return current position in netlink message
+ * @skb: socket buffer the message is stored in
+ *
+ * Returns a pointer to the current tail of the message.
+ */
+static inline void *nlmsg_get_pos(struct sk_buff *skb)
+{
+ return skb->tail;
+}
+
+/**
+ * nlmsg_trim - Trim message to a mark
+ * @skb: socket buffer the message is stored in
+ * @mark: mark to trim to
+ *
+ * Trims the message to the provided mark. Returns -1.
+ */
+static inline int nlmsg_trim(struct sk_buff *skb, void *mark)
+{
+ if (mark)
+ skb_trim(skb, (unsigned char *) mark - skb->data);
+
+ return -1;
+}
+
+/**
* nlmsg_cancel - Cancel construction of a netlink message
* @skb: socket buffer the message is stored in
* @nlh: netlink message header
@@ -489,9 +527,7 @@
*/
static inline int nlmsg_cancel(struct sk_buff *skb, struct nlmsghdr *nlh)
{
- skb_trim(skb, (unsigned char *) nlh - skb->data);
-
- return -1;
+ return nlmsg_trim(skb, nlh);
}
/**
@@ -631,6 +667,18 @@
}
/**
+ * nla_find_nested - find attribute in a set of nested attributes
+ * @nla: attribute containing the nested attributes
+ * @attrtype: type of attribute to look for
+ *
+ * Returns the first attribute which matches the specified type.
+ */
+static inline struct nlattr *nla_find_nested(struct nlattr *nla, int attrtype)
+{
+ return nla_find(nla_data(nla), nla_len(nla), attrtype);
+}
+
+/**
* nla_parse_nested - parse nested attributes
* @tb: destination array with maxtype+1 elements
* @maxtype: maximum attribute type to be expected
@@ -862,10 +910,7 @@
*/
static inline int nla_nest_cancel(struct sk_buff *skb, struct nlattr *start)
{
- if (start)
- skb_trim(skb, (unsigned char *) start - skb->data);
-
- return -1;
+ return nlmsg_trim(skb, start);
}
/**
@@ -880,4 +925,13 @@
nla_ok(pos, rem); \
pos = nla_next(pos, &(rem)))
+/**
+ * nla_for_each_nested - iterate over nested attributes
+ * @pos: loop counter, set to current attribute
+ * @nla: attribute containing the nested attributes
+ * @rem: initialized to len, holds bytes currently remaining in stream
+ */
+#define nla_for_each_nested(pos, nla, rem) \
+ nla_for_each_attr(pos, nla_data(nla), nla_len(nla), rem)
+
#endif
diff --git a/kernel/taskstats.c b/kernel/taskstats.c
index e781876..2ed4040 100644
--- a/kernel/taskstats.c
+++ b/kernel/taskstats.c
@@ -75,7 +75,7 @@
/*
* If new attributes are added, please revisit this allocation
*/
- skb = nlmsg_new(size);
+ skb = nlmsg_new(size, GFP_KERNEL);
if (!skb)
return -ENOMEM;
diff --git a/net/netlink/attr.c b/net/netlink/attr.c
index dddbd15..136e529 100644
--- a/net/netlink/attr.c
+++ b/net/netlink/attr.c
@@ -255,6 +255,26 @@
}
/**
+ * __nla_reserve_nohdr - reserve room for attribute without header
+ * @skb: socket buffer to reserve room on
+ * @attrlen: length of attribute payload
+ *
+ * Reserves room for attribute payload without a header.
+ *
+ * The caller is responsible to ensure that the skb provides enough
+ * tailroom for the payload.
+ */
+void *__nla_reserve_nohdr(struct sk_buff *skb, int attrlen)
+{
+ void *start;
+
+ start = skb_put(skb, NLA_ALIGN(attrlen));
+ memset(start, 0, NLA_ALIGN(attrlen));
+
+ return start;
+}
+
+/**
* nla_reserve - reserve room for attribute on the skb
* @skb: socket buffer to reserve room on
* @attrtype: attribute type
@@ -275,6 +295,24 @@
}
/**
+ * nla_reserve - reserve room for attribute without header
+ * @skb: socket buffer to reserve room on
+ * @len: length of attribute payload
+ *
+ * Reserves room for attribute payload without a header.
+ *
+ * Returns NULL if the tailroom of the skb is insufficient to store
+ * the attribute payload.
+ */
+void *nla_reserve_nohdr(struct sk_buff *skb, int attrlen)
+{
+ if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
+ return NULL;
+
+ return __nla_reserve_nohdr(skb, attrlen);
+}
+
+/**
* __nla_put - Add a netlink attribute to a socket buffer
* @skb: socket buffer to add attribute to
* @attrtype: attribute type
@@ -293,6 +331,22 @@
memcpy(nla_data(nla), data, attrlen);
}
+/**
+ * __nla_put_nohdr - Add a netlink attribute without header
+ * @skb: socket buffer to add attribute to
+ * @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 payload.
+ */
+void __nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)
+{
+ void *start;
+
+ start = __nla_reserve_nohdr(skb, attrlen);
+ memcpy(start, data, attrlen);
+}
/**
* nla_put - Add a netlink attribute to a socket buffer
@@ -313,15 +367,36 @@
return 0;
}
+/**
+ * nla_put_nohdr - Add a netlink attribute without header
+ * @skb: socket buffer to add attribute to
+ * @attrlen: length of attribute payload
+ * @data: head of attribute payload
+ *
+ * Returns -1 if the tailroom of the skb is insufficient to store
+ * the attribute payload.
+ */
+int nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)
+{
+ if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
+ return -1;
+
+ __nla_put_nohdr(skb, attrlen, data);
+ return 0;
+}
EXPORT_SYMBOL(nla_validate);
EXPORT_SYMBOL(nla_parse);
EXPORT_SYMBOL(nla_find);
EXPORT_SYMBOL(nla_strlcpy);
EXPORT_SYMBOL(__nla_reserve);
+EXPORT_SYMBOL(__nla_reserve_nohdr);
EXPORT_SYMBOL(nla_reserve);
+EXPORT_SYMBOL(nla_reserve_nohdr);
EXPORT_SYMBOL(__nla_put);
+EXPORT_SYMBOL(__nla_put_nohdr);
EXPORT_SYMBOL(nla_put);
+EXPORT_SYMBOL(nla_put_nohdr);
EXPORT_SYMBOL(nla_memcpy);
EXPORT_SYMBOL(nla_memcmp);
EXPORT_SYMBOL(nla_strcmp);
diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
index a298f77..75bb47a 100644
--- a/net/netlink/genetlink.c
+++ b/net/netlink/genetlink.c
@@ -440,7 +440,7 @@
struct sk_buff *skb;
int err;
- skb = nlmsg_new(NLMSG_GOODSIZE);
+ skb = nlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
if (skb == NULL)
return ERR_PTR(-ENOBUFS);
