From afdc3238ec948531205f5c5f77d2de7bae519c71 Mon Sep 17 00:00:00 2001 From: Patrick McHardy Date: Mon, 25 Jun 2007 14:30:16 -0700 Subject: [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 Signed-off-by: David S. Miller --- include/linux/rtnetlink.h | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'include/linux/rtnetlink.h') diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h index 612785848532..6731e7f4cc0f 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); \ -- cgit v1.2.3