Commit fe4944e5 authored by Thomas Graf's avatar Thomas Graf Committed by David S. Miller
Browse files

[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: default avatarThomas Graf <tgraf@suug.ch>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent e1ef4bf2
......@@ -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_memcmp(const struct nlattr *nla, const void *data,
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 @@ static inline struct nlmsghdr *nlmsg_put_answer(struct sk_buff *skb,
/**
* 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);
}
/**
......@@ -479,6 +491,32 @@ static inline int nlmsg_end(struct sk_buff *skb, struct nlmsghdr *nlh)
return skb->len;
}
/**
* 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
......@@ -489,9 +527,7 @@ static inline int nlmsg_end(struct sk_buff *skb, struct nlmsghdr *nlh)
*/
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);
}
/**
......@@ -630,6 +666,18 @@ static inline struct nlattr *nla_next(const struct nlattr *nla, int *remaining)
return (struct nlattr *) ((char *) nla + totlen);
}
/**
* 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
......@@ -862,10 +910,7 @@ static inline int nla_nest_end(struct sk_buff *skb, struct nlattr *start)
*/
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 @@ static inline int nla_nest_cancel(struct sk_buff *skb, struct nlattr *start)
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
......@@ -75,7 +75,7 @@ static int prepare_reply(struct genl_info *info, u8 cmd, struct sk_buff **skbp,
/*
* If new attributes are added, please revisit this allocation
*/
skb = nlmsg_new(size);
skb = nlmsg_new(size, GFP_KERNEL);
if (!skb)
return -ENOMEM;
......
......@@ -254,6 +254,26 @@ struct nlattr *__nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
return nla;
}
/**
* __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
......@@ -274,6 +294,24 @@ struct nlattr *nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
return __nla_reserve(skb, attrtype, attrlen);
}
/**
* 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
......@@ -293,6 +331,22 @@ void __nla_put(struct sk_buff *skb, int attrtype, int attrlen,
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 @@ int nla_put(struct sk_buff *skb, int attrtype, int attrlen, const void *data)
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);
......@@ -440,7 +440,7 @@ static struct sk_buff *ctrl_build_msg(struct genl_family *family, u32 pid,
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);
......
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