[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>

[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>
Thomas Graf · David S. Miller
1 parent e1ef4bf23b
Showing 4 changed files with 141 additions and 12 deletions Side-by-side Diff
include/net/netlink.h
kernel/taskstats.c
net/netlink/attr.c
net/netlink/genetlink.c
@@ -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);
 }
  
 /**
@@ -879,6 +924,15 @@
 	for (pos = head, rem = len; \
 	     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 @@
 	/*
 	 * If new attributes are added, please revisit this allocation
 	 */
-	skb = nlmsg_new(size);
+	skb = nlmsg_new(size, GFP_KERNEL);
 	if (!skb)
 		return -ENOMEM;
  
@@ -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
  
@@ -293,7 +331,23 @@
 	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
  * @skb: socket buffer to add attribute to
  
  
  
  
  
@@ -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);
@@ -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);
...	...	@@ -35,6 +35,8 @@
35	35	* nlmsg_put() add a netlink message to an skb
36	36	* nlmsg_put_answer() callback based nlmsg_put()
37	37	* nlmsg_end() finanlize netlink message
	38	+ * nlmsg_get_pos() return current position in message
	39	+ * nlmsg_trim() trim part of message
38	40	* nlmsg_cancel() cancel message construction
39	41	* nlmsg_free() free a netlink message
40	42	*
41	43
...	...	@@ -80,8 +82,10 @@
80	82	* struct nlattr netlink attribtue header
81	83	*
82	84	* Attribute Construction:
83		- * nla_reserve(skb, type, len) reserve skb tailroom for an attribute
	85	+ * nla_reserve(skb, type, len) reserve room for an attribute
	86	+ * nla_reserve_nohdr(skb, len) reserve room for an attribute w/o hdr
84	87	* nla_put(skb, type, len, data) add attribute to skb
	88	+ * nla_put_nohdr(skb, len, data) add attribute w/o hdr
85	89	*
86	90	* Attribute Construction for Basic Types:
87	91	* nla_put_u8(skb, type, value) add u8 attribute to skb
...	...	@@ -139,6 +143,7 @@
139	143	* nla_next(nla, remaining) get next netlink attribute
140	144	* nla_validate() validate a stream of attributes
141	145	* nla_find() find attribute in stream of attributes
	146	+ * nla_find_nested() find attribute in nested attributes
142	147	* nla_parse() parse and validate stream of attrs
143	148	* nla_parse_nested() parse nested attribuets
144	149	* nla_for_each_attr() loop over all attributes
145	150
146	151
147	152
...	...	@@ -203,12 +208,18 @@
203	208	extern int nla_strcmp(const struct nlattr nla, const char str);
204	209	extern struct nlattr * __nla_reserve(struct sk_buff *skb, int attrtype,
205	210	int attrlen);
	211	+extern void * __nla_reserve_nohdr(struct sk_buff *skb, int attrlen);
206	212	extern struct nlattr * nla_reserve(struct sk_buff *skb, int attrtype,
207	213	int attrlen);
	214	+extern void * nla_reserve_nohdr(struct sk_buff *skb, int attrlen);
208	215	extern void __nla_put(struct sk_buff *skb, int attrtype,
209	216	int attrlen, const void *data);
	217	+extern void __nla_put_nohdr(struct sk_buff *skb, int attrlen,
	218	+ const void *data);
210	219	extern int nla_put(struct sk_buff *skb, int attrtype,
211	220	int attrlen, const void *data);
	221	+extern int nla_put_nohdr(struct sk_buff *skb, int attrlen,
	222	+ const void *data);
212	223
213	224	/**************************************************************************
214	225	* Netlink Messages
215	226
216	227
...	...	@@ -453,12 +464,13 @@
453	464	/**
454	465	* nlmsg_new - Allocate a new netlink message
455	466	* @size: maximum size of message
	467	+ * @flags: the type of memory to allocate.
456	468	*
457	469	* Use NLMSG_GOODSIZE if size isn't know and you need a good default size.
458	470	*/
459		-static inline struct sk_buff *nlmsg_new(int size)
	471	+static inline struct sk_buff *nlmsg_new(int size, gfp_t flags)
460	472	{
461		- return alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
	473	+ return alloc_skb(size, flags);
462	474	}
463	475
464	476	/**
...	...	@@ -480,6 +492,32 @@
480	492	}
481	493
482	494	/**
	495	+ * nlmsg_get_pos - return current position in netlink message
	496	+ * @skb: socket buffer the message is stored in
	497	+ *
	498	+ * Returns a pointer to the current tail of the message.
	499	+ */
	500	+static inline void nlmsg_get_pos(struct sk_buff skb)
	501	+{
	502	+ return skb->tail;
	503	+}
	504	+
	505	+/**
	506	+ * nlmsg_trim - Trim message to a mark
	507	+ * @skb: socket buffer the message is stored in
	508	+ * @mark: mark to trim to
	509	+ *
	510	+ * Trims the message to the provided mark. Returns -1.
	511	+ */
	512	+static inline int nlmsg_trim(struct sk_buff skb, void mark)
	513	+{
	514	+ if (mark)
	515	+ skb_trim(skb, (unsigned char *) mark - skb->data);
	516	+
	517	+ return -1;
	518	+}
	519	+
	520	+/**
483	521	* nlmsg_cancel - Cancel construction of a netlink message
484	522	* @skb: socket buffer the message is stored in
485	523	* @nlh: netlink message header
...	...	@@ -489,9 +527,7 @@
489	527	*/
490	528	static inline int nlmsg_cancel(struct sk_buff skb, struct nlmsghdr nlh)
491	529	{
492		- skb_trim(skb, (unsigned char *) nlh - skb->data);
493		-
494		- return -1;
	530	+ return nlmsg_trim(skb, nlh);
495	531	}
496	532
497	533	/**
...	...	@@ -631,6 +667,18 @@
631	667	}
632	668
633	669	/**
	670	+ * nla_find_nested - find attribute in a set of nested attributes
	671	+ * @nla: attribute containing the nested attributes
	672	+ * @attrtype: type of attribute to look for
	673	+ *
	674	+ * Returns the first attribute which matches the specified type.
	675	+ */
	676	+static inline struct nlattr nla_find_nested(struct nlattr nla, int attrtype)
	677	+{
	678	+ return nla_find(nla_data(nla), nla_len(nla), attrtype);
	679	+}
	680	+
	681	+/**
634	682	* nla_parse_nested - parse nested attributes
635	683	* @tb: destination array with maxtype+1 elements
636	684	* @maxtype: maximum attribute type to be expected
...	...	@@ -862,10 +910,7 @@
862	910	*/
863	911	static inline int nla_nest_cancel(struct sk_buff skb, struct nlattr start)
864	912	{
865		- if (start)
866		- skb_trim(skb, (unsigned char *) start - skb->data);
867		-
868		- return -1;
	913	+ return nlmsg_trim(skb, start);
869	914	}
870	915
871	916	/**
...	...	@@ -879,6 +924,15 @@
879	924	for (pos = head, rem = len; \
880	925	nla_ok(pos, rem); \
881	926	pos = nla_next(pos, &(rem)))
	927	+
	928	+/**
	929	+ * nla_for_each_nested - iterate over nested attributes
	930	+ * @pos: loop counter, set to current attribute
	931	+ * @nla: attribute containing the nested attributes
	932	+ * @rem: initialized to len, holds bytes currently remaining in stream
	933	+ */
	934	+#define nla_for_each_nested(pos, nla, rem) \
	935	+ nla_for_each_attr(pos, nla_data(nla), nla_len(nla), rem)
882	936
883	937	#endif
...	...	@@ -75,7 +75,7 @@
75	75	/*
76	76	* If new attributes are added, please revisit this allocation
77	77	*/
78		- skb = nlmsg_new(size);
	78	+ skb = nlmsg_new(size, GFP_KERNEL);
79	79	if (!skb)
80	80	return -ENOMEM;
81	81
...	...	@@ -255,6 +255,26 @@
255	255	}
256	256
257	257	/**
	258	+ * __nla_reserve_nohdr - reserve room for attribute without header
	259	+ * @skb: socket buffer to reserve room on
	260	+ * @attrlen: length of attribute payload
	261	+ *
	262	+ * Reserves room for attribute payload without a header.
	263	+ *
	264	+ * The caller is responsible to ensure that the skb provides enough
	265	+ * tailroom for the payload.
	266	+ */
	267	+void __nla_reserve_nohdr(struct sk_buff skb, int attrlen)
	268	+{
	269	+ void *start;
	270	+
	271	+ start = skb_put(skb, NLA_ALIGN(attrlen));
	272	+ memset(start, 0, NLA_ALIGN(attrlen));
	273	+
	274	+ return start;
	275	+}
	276	+
	277	+/**
258	278	* nla_reserve - reserve room for attribute on the skb
259	279	* @skb: socket buffer to reserve room on
260	280	* @attrtype: attribute type
...	...	@@ -275,6 +295,24 @@
275	295	}
276	296
277	297	/**
	298	+ * nla_reserve - reserve room for attribute without header
	299	+ * @skb: socket buffer to reserve room on
	300	+ * @len: length of attribute payload
	301	+ *
	302	+ * Reserves room for attribute payload without a header.
	303	+ *
	304	+ * Returns NULL if the tailroom of the skb is insufficient to store
	305	+ * the attribute payload.
	306	+ */
	307	+void nla_reserve_nohdr(struct sk_buff skb, int attrlen)
	308	+{
	309	+ if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
	310	+ return NULL;
	311	+
	312	+ return __nla_reserve_nohdr(skb, attrlen);
	313	+}
	314	+
	315	+/**
278	316	* __nla_put - Add a netlink attribute to a socket buffer
279	317	* @skb: socket buffer to add attribute to
280	318	* @attrtype: attribute type
281	319
...	...	@@ -293,7 +331,23 @@
293	331	memcpy(nla_data(nla), data, attrlen);
294	332	}
295	333
	334	+/**
	335	+ * __nla_put_nohdr - Add a netlink attribute without header
	336	+ * @skb: socket buffer to add attribute to
	337	+ * @attrlen: length of attribute payload
	338	+ * @data: head of attribute payload
	339	+ *
	340	+ * The caller is responsible to ensure that the skb provides enough
	341	+ * tailroom for the attribute payload.
	342	+ */
	343	+void __nla_put_nohdr(struct sk_buff skb, int attrlen, const void data)
	344	+{
	345	+ void *start;
296	346
	347	+ start = __nla_reserve_nohdr(skb, attrlen);
	348	+ memcpy(start, data, attrlen);
	349	+}
	350	+
297	351	/**
298	352	* nla_put - Add a netlink attribute to a socket buffer
299	353	* @skb: socket buffer to add attribute to
300	354
301	355
302	356
303	357
304	358
...	...	@@ -313,15 +367,36 @@
313	367	return 0;
314	368	}
315	369
	370	+/**
	371	+ * nla_put_nohdr - Add a netlink attribute without header
	372	+ * @skb: socket buffer to add attribute to
	373	+ * @attrlen: length of attribute payload
	374	+ * @data: head of attribute payload
	375	+ *
	376	+ * Returns -1 if the tailroom of the skb is insufficient to store
	377	+ * the attribute payload.
	378	+ */
	379	+int nla_put_nohdr(struct sk_buff skb, int attrlen, const void data)
	380	+{
	381	+ if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
	382	+ return -1;
316	383
	384	+ __nla_put_nohdr(skb, attrlen, data);
	385	+ return 0;
	386	+}
	387	+
317	388	EXPORT_SYMBOL(nla_validate);
318	389	EXPORT_SYMBOL(nla_parse);
319	390	EXPORT_SYMBOL(nla_find);
320	391	EXPORT_SYMBOL(nla_strlcpy);
321	392	EXPORT_SYMBOL(__nla_reserve);
	393	+EXPORT_SYMBOL(__nla_reserve_nohdr);
322	394	EXPORT_SYMBOL(nla_reserve);
	395	+EXPORT_SYMBOL(nla_reserve_nohdr);
323	396	EXPORT_SYMBOL(__nla_put);
	397	+EXPORT_SYMBOL(__nla_put_nohdr);
324	398	EXPORT_SYMBOL(nla_put);
	399	+EXPORT_SYMBOL(nla_put_nohdr);
325	400	EXPORT_SYMBOL(nla_memcpy);
326	401	EXPORT_SYMBOL(nla_memcmp);
327	402	EXPORT_SYMBOL(nla_strcmp);
...	...	@@ -440,7 +440,7 @@
440	440	struct sk_buff *skb;
441	441	int err;
442	442
443		- skb = nlmsg_new(NLMSG_GOODSIZE);
	443	+ skb = nlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
444	444	if (skb == NULL)
445	445	return ERR_PTR(-ENOBUFS);
446	446