Commit 8cbc8708 authored by Pablo Neira's avatar Pablo Neira Committed by Pablo Neira Ayuso
Browse files

netfilter: nfnetlink_log: validate dependencies to avoid breaking atomicity 



Check that dependencies are fulfilled before updating the logger
instance, otherwise we can leave things in intermediate state on errors
in nfulnl_recv_config().

[ Ken-ichirou reports that this is also fixing missing instance refcnt drop
  on error introduced in his patch 914eebf2 ("netfilter: nfnetlink_log:
  autoload nf_conntrack_netlink module NFQA_CFG_F_CONNTRACK config flag"). ]

Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
Tested-by: default avatarKen-ichirou MATSUZAWA <chamaken@gmail.com>
parent 336a3b3e

net/netfilter/nfnetlink_log.c

+24 −19
Original line number Diff line number Diff line
@@ -825,6 +825,7 @@ nfulnl_recv_config(struct sock *ctnl, struct sk_buff *skb, 
	struct net *net = sock_net(ctnl);

	struct nfnl_log_net *log = nfnl_log_pernet(net);

	int ret = 0;

	u16 flags;



	if (nfula[NFULA_CFG_CMD]) {

		u_int8_t pf = nfmsg->nfgen_family;
@@ -846,6 +847,28 @@ nfulnl_recv_config(struct sock *ctnl, struct sk_buff *skb, 
		goto out_put;

	}



	/* Check if we support these flags in first place, dependencies should

	 * be there too not to break atomicity.

	 */

	if (nfula[NFULA_CFG_FLAGS]) {

		flags = ntohs(nla_get_be16(nfula[NFULA_CFG_FLAGS]));



		if ((flags & NFULNL_CFG_F_CONNTRACK) &&

		    !rcu_access_pointer(nfnl_ct_hook)) {

#ifdef CONFIG_MODULES

			nfnl_unlock(NFNL_SUBSYS_ULOG);

			request_module("ip_conntrack_netlink");

			nfnl_lock(NFNL_SUBSYS_ULOG);

			if (rcu_access_pointer(nfnl_ct_hook)) {

				ret = -EAGAIN;

				goto out_put;

			}

#endif

			ret = -EOPNOTSUPP;

			goto out_put;

		}

	}



	if (cmd != NULL) {

		switch (cmd->command) {

		case NFULNL_CFG_CMD_BIND:
@@ -905,26 +928,8 @@ nfulnl_recv_config(struct sock *ctnl, struct sk_buff *skb, 
		nfulnl_set_qthresh(inst, ntohl(qthresh));

	}



	if (nfula[NFULA_CFG_FLAGS]) {

		u16 flags = ntohs(nla_get_be16(nfula[NFULA_CFG_FLAGS]));



		if (flags & NFULNL_CFG_F_CONNTRACK &&

		    !rcu_access_pointer(nfnl_ct_hook)) {

#ifdef CONFIG_MODULES

			nfnl_unlock(NFNL_SUBSYS_ULOG);

			request_module("ip_conntrack_netlink");

			nfnl_lock(NFNL_SUBSYS_ULOG);

			if (rcu_access_pointer(nfnl_ct_hook)) {

				ret = -EAGAIN;

				goto out;

			}

#endif

			ret = -EOPNOTSUPP;

			goto out;

		}



	if (nfula[NFULA_CFG_FLAGS])

		nfulnl_set_flags(inst, flags);

	}



out_put:

	instance_put(inst);

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