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Commit b424e432 authored by Michal Kubecek's avatar Michal Kubecek Committed by David S. Miller
Browse files

netlink: add validation of NLA_F_NESTED flag 



Add new validation flag NL_VALIDATE_NESTED which adds three consistency
checks of NLA_F_NESTED_FLAG:

  - the flag is set on attributes with NLA_NESTED{,_ARRAY} policy
  - the flag is not set on attributes with other policies except NLA_UNSPEC
  - the flag is set on attribute passed to nla_parse_nested()

Signed-off-by: default avatarMichal Kubecek <mkubecek@suse.cz>

v2: change error messages to mention NLA_F_NESTED explicitly
Reviewed-by: default avatarJohannes Berg <johannes@sipsolutions.net>
Reviewed-by: default avatarDavid Ahern <dsahern@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent d54a16b2

include/net/netlink.h

+10 −1
Original line number Diff line number Diff line
@@ -401,6 +401,8 @@ struct nl_info { 
 *	are enforced going forward.

 * @NL_VALIDATE_STRICT_ATTRS: strict attribute policy parsing (e.g.

 *	U8, U16, U32 must have exact size, etc.)

 * @NL_VALIDATE_NESTED: Check that NLA_F_NESTED is set for NLA_NESTED(_ARRAY)

 *	and unset for other policies.

 */

enum netlink_validation {

	NL_VALIDATE_LIBERAL = 0,
@@ -408,6 +410,7 @@ enum netlink_validation { 
	NL_VALIDATE_MAXTYPE = BIT(1),

	NL_VALIDATE_UNSPEC = BIT(2),

	NL_VALIDATE_STRICT_ATTRS = BIT(3),

	NL_VALIDATE_NESTED = BIT(4),

};



#define NL_VALIDATE_DEPRECATED_STRICT (NL_VALIDATE_TRAILING |\
@@ -415,7 +418,8 @@ enum netlink_validation { 
#define NL_VALIDATE_STRICT (NL_VALIDATE_TRAILING |\

			    NL_VALIDATE_MAXTYPE |\

			    NL_VALIDATE_UNSPEC |\

			    NL_VALIDATE_STRICT_ATTRS)

			    NL_VALIDATE_STRICT_ATTRS |\

			    NL_VALIDATE_NESTED)



int netlink_rcv_skb(struct sk_buff *skb,

		    int (*cb)(struct sk_buff *, struct nlmsghdr *,
@@ -1132,6 +1136,11 @@ static inline int nla_parse_nested(struct nlattr *tb[], int maxtype, 
				   const struct nla_policy *policy,

				   struct netlink_ext_ack *extack)

{

	if (!(nla->nla_type & NLA_F_NESTED)) {

		NL_SET_ERR_MSG_ATTR(extack, nla, "NLA_F_NESTED is missing");

		return -EINVAL;

	}



	return __nla_parse(tb, maxtype, nla_data(nla), nla_len(nla), policy,

			   NL_VALIDATE_STRICT, extack);

}

lib/nlattr.c

+15 −0
Original line number Diff line number Diff line
@@ -184,6 +184,21 @@ static int validate_nla(const struct nlattr *nla, int maxtype, 
		}

	}



	if (validate & NL_VALIDATE_NESTED) {

		if ((pt->type == NLA_NESTED || pt->type == NLA_NESTED_ARRAY) &&

		    !(nla->nla_type & NLA_F_NESTED)) {

			NL_SET_ERR_MSG_ATTR(extack, nla,

					    "NLA_F_NESTED is missing");

			return -EINVAL;

		}

		if (pt->type != NLA_NESTED && pt->type != NLA_NESTED_ARRAY &&

		    pt->type != NLA_UNSPEC && (nla->nla_type & NLA_F_NESTED)) {

			NL_SET_ERR_MSG_ATTR(extack, nla,

					    "NLA_F_NESTED not expected");

			return -EINVAL;

		}

	}



	switch (pt->type) {

	case NLA_EXACT_LEN:

		if (attrlen != pt->len)