David Miller wrote:
From: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
SKF_AD_NLATTR allows us to find the first matching attribute in a
stream of netlink attributes from one offset to the end of the
netlink message. This is not suitable to look for a specific
matching inside a set of nested attributes.
For example, in ctnetlink messages, if we look for the CTA_V6_SRC
attribute in a message that talks about an IPv4 connection,
SKF_AD_NLATTR returns the offset of CTA_STATUS which has the same
value of CTA_V6_SRC but outside the nest. To differenciate
CTA_STATUS and CTA_V6_SRC, we would have to make assumptions on the
size of the attribute and the usual offset, resulting in horrible
BSF code.
This patch adds SKF_AD_NLATTR_NEST, which is a variant of
SKF_AD_NLATTR, that looks for an attribute inside the limits of
a nested attributes, but not further.
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
This looks fine to me, Patrick is it ok with you too?
If Patrick has no objections I'll apply it to net-next-2.6
I think this needs more validation to avoid overruning the skb data:
+ case SKF_AD_NLATTR_NEST: {
+ struct nlattr *nla;
+
+ if (skb_is_nonlinear(skb))
+ return 0;
+ if (A > skb->len - sizeof(struct nlattr))
+ return 0;
+
+ nla = nla_find_nested((struct nlattr *)&skb->data[A],X);
This interprets skb->data as nlattr and takes the nla_len member
as limit for nla_find(), so it needs to be validated not to exceed
the skb length.
Besides that, the patch looks fine.
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