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[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>
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@ -35,6 +35,8 @@
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* nlmsg_put() add a netlink message to an skb
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* nlmsg_put_answer() callback based nlmsg_put()
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* nlmsg_end() finanlize netlink message
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* nlmsg_get_pos() return current position in message
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* nlmsg_trim() trim part of message
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* nlmsg_cancel() cancel message construction
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* nlmsg_free() free a netlink message
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*
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@ -80,8 +82,10 @@
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* struct nlattr netlink attribtue header
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*
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* Attribute Construction:
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* nla_reserve(skb, type, len) reserve skb tailroom for an attribute
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* nla_reserve(skb, type, len) reserve room for an attribute
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* nla_reserve_nohdr(skb, len) reserve room for an attribute w/o hdr
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* nla_put(skb, type, len, data) add attribute to skb
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* nla_put_nohdr(skb, len, data) add attribute w/o hdr
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*
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* Attribute Construction for Basic Types:
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* nla_put_u8(skb, type, value) add u8 attribute to skb
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@ -139,6 +143,7 @@
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* nla_next(nla, remaining) get next netlink attribute
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* nla_validate() validate a stream of attributes
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* nla_find() find attribute in stream of attributes
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* nla_find_nested() find attribute in nested attributes
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* nla_parse() parse and validate stream of attrs
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* nla_parse_nested() parse nested attribuets
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* nla_for_each_attr() loop over all attributes
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@ -203,12 +208,18 @@ extern int nla_memcmp(const struct nlattr *nla, const void *data,
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extern int nla_strcmp(const struct nlattr *nla, const char *str);
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extern struct nlattr * __nla_reserve(struct sk_buff *skb, int attrtype,
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int attrlen);
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extern void * __nla_reserve_nohdr(struct sk_buff *skb, int attrlen);
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extern struct nlattr * nla_reserve(struct sk_buff *skb, int attrtype,
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int attrlen);
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extern void * nla_reserve_nohdr(struct sk_buff *skb, int attrlen);
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extern void __nla_put(struct sk_buff *skb, int attrtype,
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int attrlen, const void *data);
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extern void __nla_put_nohdr(struct sk_buff *skb, int attrlen,
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const void *data);
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extern int nla_put(struct sk_buff *skb, int attrtype,
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int attrlen, const void *data);
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extern int nla_put_nohdr(struct sk_buff *skb, int attrlen,
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const void *data);
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/**************************************************************************
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* Netlink Messages
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@ -453,12 +464,13 @@ static inline struct nlmsghdr *nlmsg_put_answer(struct sk_buff *skb,
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/**
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* nlmsg_new - Allocate a new netlink message
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* @size: maximum size of message
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* @flags: the type of memory to allocate.
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*
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* Use NLMSG_GOODSIZE if size isn't know and you need a good default size.
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*/
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static inline struct sk_buff *nlmsg_new(int size)
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static inline struct sk_buff *nlmsg_new(int size, gfp_t flags)
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{
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return alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
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return alloc_skb(size, flags);
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}
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/**
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@ -479,6 +491,32 @@ static inline int nlmsg_end(struct sk_buff *skb, struct nlmsghdr *nlh)
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return skb->len;
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}
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/**
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* nlmsg_get_pos - return current position in netlink message
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* @skb: socket buffer the message is stored in
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*
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* Returns a pointer to the current tail of the message.
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*/
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static inline void *nlmsg_get_pos(struct sk_buff *skb)
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{
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return skb->tail;
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}
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/**
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* nlmsg_trim - Trim message to a mark
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* @skb: socket buffer the message is stored in
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* @mark: mark to trim to
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*
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* Trims the message to the provided mark. Returns -1.
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*/
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static inline int nlmsg_trim(struct sk_buff *skb, void *mark)
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{
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if (mark)
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skb_trim(skb, (unsigned char *) mark - skb->data);
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return -1;
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}
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/**
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* nlmsg_cancel - Cancel construction of a netlink message
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* @skb: socket buffer the message is stored in
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@ -489,9 +527,7 @@ static inline int nlmsg_end(struct sk_buff *skb, struct nlmsghdr *nlh)
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*/
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static inline int nlmsg_cancel(struct sk_buff *skb, struct nlmsghdr *nlh)
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{
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skb_trim(skb, (unsigned char *) nlh - skb->data);
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return -1;
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return nlmsg_trim(skb, nlh);
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}
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/**
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@ -630,6 +666,18 @@ static inline struct nlattr *nla_next(const struct nlattr *nla, int *remaining)
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return (struct nlattr *) ((char *) nla + totlen);
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}
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/**
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* nla_find_nested - find attribute in a set of nested attributes
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* @nla: attribute containing the nested attributes
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* @attrtype: type of attribute to look for
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*
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* Returns the first attribute which matches the specified type.
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*/
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static inline struct nlattr *nla_find_nested(struct nlattr *nla, int attrtype)
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{
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return nla_find(nla_data(nla), nla_len(nla), attrtype);
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}
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/**
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* nla_parse_nested - parse nested attributes
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* @tb: destination array with maxtype+1 elements
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@ -862,10 +910,7 @@ static inline int nla_nest_end(struct sk_buff *skb, struct nlattr *start)
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*/
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static inline int nla_nest_cancel(struct sk_buff *skb, struct nlattr *start)
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{
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if (start)
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skb_trim(skb, (unsigned char *) start - skb->data);
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return -1;
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return nlmsg_trim(skb, start);
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}
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/**
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@ -880,4 +925,13 @@ static inline int nla_nest_cancel(struct sk_buff *skb, struct nlattr *start)
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nla_ok(pos, rem); \
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pos = nla_next(pos, &(rem)))
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/**
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* nla_for_each_nested - iterate over nested attributes
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* @pos: loop counter, set to current attribute
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* @nla: attribute containing the nested attributes
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* @rem: initialized to len, holds bytes currently remaining in stream
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*/
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#define nla_for_each_nested(pos, nla, rem) \
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nla_for_each_attr(pos, nla_data(nla), nla_len(nla), rem)
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#endif
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@ -75,7 +75,7 @@ static int prepare_reply(struct genl_info *info, u8 cmd, struct sk_buff **skbp,
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/*
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* If new attributes are added, please revisit this allocation
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*/
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skb = nlmsg_new(size);
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skb = nlmsg_new(size, GFP_KERNEL);
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if (!skb)
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return -ENOMEM;
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@ -254,6 +254,26 @@ struct nlattr *__nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
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return nla;
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}
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/**
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* __nla_reserve_nohdr - reserve room for attribute without header
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* @skb: socket buffer to reserve room on
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* @attrlen: length of attribute payload
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*
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* Reserves room for attribute payload without a header.
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*
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* The caller is responsible to ensure that the skb provides enough
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* tailroom for the payload.
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*/
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void *__nla_reserve_nohdr(struct sk_buff *skb, int attrlen)
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{
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void *start;
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start = skb_put(skb, NLA_ALIGN(attrlen));
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memset(start, 0, NLA_ALIGN(attrlen));
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return start;
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}
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/**
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* nla_reserve - reserve room for attribute on the skb
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* @skb: socket buffer to reserve room on
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@ -274,6 +294,24 @@ struct nlattr *nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
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return __nla_reserve(skb, attrtype, attrlen);
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}
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/**
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* nla_reserve - reserve room for attribute without header
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* @skb: socket buffer to reserve room on
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* @len: length of attribute payload
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*
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* Reserves room for attribute payload without a header.
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*
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* Returns NULL if the tailroom of the skb is insufficient to store
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* the attribute payload.
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*/
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void *nla_reserve_nohdr(struct sk_buff *skb, int attrlen)
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{
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if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
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return NULL;
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return __nla_reserve_nohdr(skb, attrlen);
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}
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/**
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* __nla_put - Add a netlink attribute to a socket buffer
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* @skb: socket buffer to add attribute to
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@ -293,6 +331,22 @@ void __nla_put(struct sk_buff *skb, int attrtype, int attrlen,
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memcpy(nla_data(nla), data, attrlen);
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}
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/**
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* __nla_put_nohdr - Add a netlink attribute without header
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* @skb: socket buffer to add attribute to
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* @attrlen: length of attribute payload
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* @data: head of attribute payload
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*
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* The caller is responsible to ensure that the skb provides enough
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* tailroom for the attribute payload.
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*/
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void __nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)
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{
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void *start;
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start = __nla_reserve_nohdr(skb, attrlen);
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memcpy(start, data, attrlen);
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}
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/**
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* nla_put - Add a netlink attribute to a socket buffer
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@ -313,15 +367,36 @@ int nla_put(struct sk_buff *skb, int attrtype, int attrlen, const void *data)
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return 0;
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}
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/**
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* nla_put_nohdr - Add a netlink attribute without header
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* @skb: socket buffer to add attribute to
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* @attrlen: length of attribute payload
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* @data: head of attribute payload
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*
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* Returns -1 if the tailroom of the skb is insufficient to store
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* the attribute payload.
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*/
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int nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)
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{
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if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
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return -1;
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__nla_put_nohdr(skb, attrlen, data);
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return 0;
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}
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EXPORT_SYMBOL(nla_validate);
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EXPORT_SYMBOL(nla_parse);
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EXPORT_SYMBOL(nla_find);
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EXPORT_SYMBOL(nla_strlcpy);
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EXPORT_SYMBOL(__nla_reserve);
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EXPORT_SYMBOL(__nla_reserve_nohdr);
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EXPORT_SYMBOL(nla_reserve);
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EXPORT_SYMBOL(nla_reserve_nohdr);
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EXPORT_SYMBOL(__nla_put);
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EXPORT_SYMBOL(__nla_put_nohdr);
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EXPORT_SYMBOL(nla_put);
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EXPORT_SYMBOL(nla_put_nohdr);
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EXPORT_SYMBOL(nla_memcpy);
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EXPORT_SYMBOL(nla_memcmp);
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EXPORT_SYMBOL(nla_strcmp);
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@ -440,7 +440,7 @@ static struct sk_buff *ctrl_build_msg(struct genl_family *family, u32 pid,
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struct sk_buff *skb;
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int err;
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skb = nlmsg_new(NLMSG_GOODSIZE);
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skb = nlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
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if (skb == NULL)
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return ERR_PTR(-ENOBUFS);
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