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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 /net
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 'net')
-rw-r--r--net/core/rtnetlink.c16
1 files changed, 16 insertions, 0 deletions
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 06c0c5afabf..c25d23ba6d5 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -97,6 +97,21 @@ int rtattr_parse(struct rtattr *tb[], int maxattr, struct rtattr *rta, int len)
return 0;
}
+int rtattr_parse_nested_compat(struct rtattr *tb[], int maxattr,
+ struct rtattr *rta, void **data, int len)
+{
+ if (RTA_PAYLOAD(rta) < len)
+ return -1;
+ *data = RTA_DATA(rta);
+
+ if (RTA_PAYLOAD(rta) >= RTA_ALIGN(len) + sizeof(struct rtattr)) {
+ rta = RTA_DATA(rta) + RTA_ALIGN(len);
+ return rtattr_parse_nested(tb, maxattr, rta);
+ }
+ memset(tb, 0, sizeof(struct rtattr *) * maxattr);
+ return 0;
+}
+
static struct rtnl_link *rtnl_msg_handlers[NPROTO];
static inline int rtm_msgindex(int msgtype)
@@ -1297,6 +1312,7 @@ void __init rtnetlink_init(void)
EXPORT_SYMBOL(__rta_fill);
EXPORT_SYMBOL(rtattr_strlcpy);
EXPORT_SYMBOL(rtattr_parse);
+EXPORT_SYMBOL(rtattr_parse_nested_compat);
EXPORT_SYMBOL(rtnetlink_put_metrics);
EXPORT_SYMBOL(rtnl_lock);
EXPORT_SYMBOL(rtnl_trylock);