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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 914eebf2f4 ("netfilter: nfnetlink_log:
  autoload nf_conntrack_netlink module NFQA_CFG_F_CONNTRACK config flag"). ]

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Tested-by: Ken-ichirou MATSUZAWA <chamaken@gmail.com>
This commit is contained in:
Pablo Neira 2015-10-13 12:47:48 +02:00 committed by Pablo Neira Ayuso
parent 336a3b3ee9
commit 8cbc870829
1 changed files with 24 additions and 19 deletions
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43
net/netfilter/nfnetlink_log.c
View File

@ -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);