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authorPatrick McHardy <kaber@trash.net>2007-06-25 14:30:16 -0700
committerDavid S. Miller <davem@sunset.davemloft.net>2007-07-10 22:15:39 -0700
commitafdc3238ec948531205f5c5f77d2de7bae519c71 (patch)
treece69a6ed3095ba5049673340304672381068b3af /include
parent1092cb219774a82b1f16781aec7b8d4ec727c981 (diff)
[RTNETLINK]: Add nested compat attribute
Add a nested compat attribute type that can be used to convert attributes that contain a structure to nested attributes in a backwards compatible way. The attribute looks like this: struct { [ compat contents ] struct rtattr { .rta_len = total size, .rta_type = type, } rta; struct old_structure struct; [ nested top-level attribute ] struct rtattr { .rta_len = nest size, .rta_type = type, } nest_attr; [ optional 0 .. n nested attributes ] struct rtattr { .rta_len = private attribute len, .rta_type = private attribute typ, } nested_attr; struct nested_data data; }; Since both userspace and kernel deal correctly with attributes that are larger than expected old versions will just parse the compat part and ignore the rest. Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include')
-rw-r--r--include/linux/rtnetlink.h14
1 files changed, 14 insertions, 0 deletions
diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h
index 61278584853..6731e7f4cc0 100644
--- a/include/linux/rtnetlink.h
+++ b/include/linux/rtnetlink.h
@@ -570,6 +570,8 @@ static __inline__ int rtattr_strcmp(const struct rtattr *rta, const char *str)
}
extern int rtattr_parse(struct rtattr *tb[], int maxattr, struct rtattr *rta, int len);
+extern int rtattr_parse_nested_compat(struct rtattr *tb[], int maxattr,
+ struct rtattr *rta, void **data, int len);
#define rtattr_parse_nested(tb, max, rta) \
rtattr_parse((tb), (max), RTA_DATA((rta)), RTA_PAYLOAD((rta)))
@@ -638,6 +640,18 @@ extern void __rta_fill(struct sk_buff *skb, int attrtype, int attrlen, const voi
({ (start)->rta_len = skb_tail_pointer(skb) - (unsigned char *)(start); \
(skb)->len; })
+#define RTA_NEST_COMPAT(skb, type, attrlen, data) \
+({ struct rtattr *__start = (struct rtattr *)skb_tail_pointer(skb); \
+ RTA_PUT(skb, type, attrlen, data); \
+ RTA_NEST(skb, type); \
+ __start; })
+
+#define RTA_NEST_COMPAT_END(skb, start) \
+({ struct rtattr *__nest = (void *)(start) + NLMSG_ALIGN((start)->rta_len); \
+ (start)->rta_len = skb_tail_pointer(skb) - (unsigned char *)(start); \
+ RTA_NEST_END(skb, __nest); \
+ (skb)->len; })
+
#define RTA_NEST_CANCEL(skb, start) \
({ if (start) \
skb_trim(skb, (unsigned char *) (start) - (skb)->data); \