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Commit e3730578 authored by Patrick McHardy's avatar Patrick McHardy Committed by David S. Miller
Browse files

[NETFILTER]: nfnetlink: support attribute policies 



Add support for automatic checking of per-callback attribute policies.

Signed-off-by: default avatarPatrick McHardy <kaber@trash.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent dd82185f

include/linux/netfilter/nfnetlink.h

+2 −1
Original line number Diff line number Diff line
@@ -58,7 +58,8 @@ struct nfnl_callback 
{

	int (*call)(struct sock *nl, struct sk_buff *skb, 

		struct nlmsghdr *nlh, struct nlattr *cda[]);

	u_int16_t attr_count;	/* number of nlattr's */

	const struct nla_policy *policy;	/* netlink attribute policy */

	const u_int16_t attr_count;		/* number of nlattr's */

};



struct nfnetlink_subsystem

net/netfilter/nfnetlink.c

+13 −35
Original line number Diff line number Diff line
@@ -111,35 +111,6 @@ nfnetlink_find_client(u_int16_t type, const struct nfnetlink_subsystem *ss) 
	return &ss->cb[cb_id];

}



/**

 * nfnetlink_check_attributes - check and parse nfnetlink attributes

 *

 * subsys: nfnl subsystem for which this message is to be parsed

 * nlmsghdr: netlink message to be checked/parsed

 * cda: array of pointers, needs to be at least subsys->attr_count+1 big

 *

 */

static int

nfnetlink_check_attributes(const struct nfnetlink_subsystem *subsys,

			   struct nlmsghdr *nlh, struct nlattr *cda[])

{

	int min_len = NLMSG_SPACE(sizeof(struct nfgenmsg));

	u_int8_t cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);

	u_int16_t attr_count = subsys->cb[cb_id].attr_count;



	/* check attribute lengths. */

	if (likely(nlh->nlmsg_len > min_len)) {

		struct nlattr *attr = (void *)nlh + NLMSG_ALIGN(min_len);

		int attrlen = nlh->nlmsg_len - NLMSG_ALIGN(min_len);

		nla_parse(cda, attr_count, attr, attrlen, NULL);

	}



	/* implicit: if nlmsg_len == min_len, we return 0, and an empty

	 * (zeroed) cda[] array. The message is valid, but empty. */



	return 0;

}



int nfnetlink_has_listeners(unsigned int group)

{

	return netlink_has_listeners(nfnl, group);
@@ -192,15 +163,22 @@ static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh) 
		return -EINVAL;



	{

		u_int16_t attr_count =

			ss->cb[NFNL_MSG_TYPE(nlh->nlmsg_type)].attr_count;

		int min_len = NLMSG_SPACE(sizeof(struct nfgenmsg));

		u_int8_t cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);

		u_int16_t attr_count = ss->cb[cb_id].attr_count;

		struct nlattr *cda[attr_count+1];



		memset(cda, 0, sizeof(struct nlattr *) * attr_count);

		if (likely(nlh->nlmsg_len >= min_len)) {

			struct nlattr *attr = (void *)nlh + NLMSG_ALIGN(min_len);

			int attrlen = nlh->nlmsg_len - NLMSG_ALIGN(min_len);



		err = nfnetlink_check_attributes(ss, nlh, cda);

			err = nla_parse(cda, attr_count, attr, attrlen,

					ss->cb[cb_id].policy);

			if (err < 0)

				return err;

		} else

			return -EINVAL;



		return nc->call(nfnl, skb, nlh, cda);

	}

}