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netfilter: ipset: Make sure listing doesn't grab a set which is just being destroyed.

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There was a small window when all sets are destroyed and a concurrent
listing of all sets could grab a set which is just being destroyed.

Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
This commit is contained in:
Jozsef Kadlecsik 2015-06-13 13:39:38 +02:00
parent c4c997839c
commit 9c1ba5c809
1 changed files with 34 additions and 15 deletions
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49
net/netfilter/ipset/ip_set_core.c
View File

@ -32,7 +32,8 @@ static DEFINE_RWLOCK(ip_set_ref_lock); /* protects the set refs */
struct ip_set_net {
struct ip_set * __rcu *ip_set_list; /* all individual sets */
ip_set_id_t ip_set_max; /* max number of sets */
int is_deleted; /* deleted by ip_set_net_exit */
bool is_deleted; /* deleted by ip_set_net_exit */
bool is_destroyed; /* all sets are destroyed */
};
static int ip_set_net_id __read_mostly;
@ -980,12 +981,9 @@ ip_set_setname_policy[IPSET_ATTR_CMD_MAX + 1] = {
};
static void
ip_set_destroy_set(struct ip_set_net *inst, ip_set_id_t index)
ip_set_destroy_set(struct ip_set *set)
{
struct ip_set *set = ip_set(inst, index);
pr_debug("set: %s\n", set->name);
ip_set(inst, index) = NULL;
/* Must call it without holding any lock */
set->variant->destroy(set);
@ -1025,12 +1023,17 @@ ip_set_destroy(struct sock *ctnl, struct sk_buff *skb,
goto out;
}
}
inst->is_destroyed = true;
read_unlock_bh(&ip_set_ref_lock);
for (i = 0; i < inst->ip_set_max; i++) {
s = ip_set(inst, i);
if (s != NULL)
ip_set_destroy_set(inst, i);
if (s) {
ip_set(inst, i) = NULL;
ip_set_destroy_set(s);
}
}
/* Modified by ip_set_destroy() only, which is serialized */
inst->is_destroyed = false;
} else {
s = find_set_and_id(inst, nla_data(attr[IPSET_ATTR_SETNAME]),
&i);
@ -1041,9 +1044,10 @@ ip_set_destroy(struct sock *ctnl, struct sk_buff *skb,
ret = -IPSET_ERR_BUSY;
goto out;
}
ip_set(inst, i) = NULL;
read_unlock_bh(&ip_set_ref_lock);
ip_set_destroy_set(inst, i);
ip_set_destroy_set(s);
}
return 0;
out:
@ -1283,6 +1287,7 @@ ip_set_dump_start(struct sk_buff *skb, struct netlink_callback *cb)
unsigned int flags = NETLINK_CB(cb->skb).portid ? NLM_F_MULTI : 0;
struct ip_set_net *inst = ip_set_pernet(sock_net(skb->sk));
u32 dump_type, dump_flags;
bool is_destroyed;
int ret = 0;
if (!cb->args[IPSET_CB_DUMP]) {
@ -1309,12 +1314,20 @@ ip_set_dump_start(struct sk_buff *skb, struct netlink_callback *cb)
dump_type, dump_flags, cb->args[IPSET_CB_INDEX]);
for (; cb->args[IPSET_CB_INDEX] < max; cb->args[IPSET_CB_INDEX]++) {
index = (ip_set_id_t) cb->args[IPSET_CB_INDEX];
write_lock_bh(&ip_set_ref_lock);
set = ip_set(inst, index);
if (set == NULL) {
is_destroyed = inst->is_destroyed;
if (!set || is_destroyed) {
write_unlock_bh(&ip_set_ref_lock);
if (dump_type == DUMP_ONE) {
ret = -ENOENT;
goto out;
}
if (is_destroyed) {
/* All sets are just being destroyed */
ret = 0;
goto out;
}
continue;
}
/* When dumping all sets, we must dump "sorted"
@ -1322,14 +1335,17 @@ ip_set_dump_start(struct sk_buff *skb, struct netlink_callback *cb)
*/
if (dump_type != DUMP_ONE &&
((dump_type == DUMP_ALL) ==
!!(set->type->features & IPSET_DUMP_LAST)))
!!(set->type->features & IPSET_DUMP_LAST))) {
write_unlock_bh(&ip_set_ref_lock);
continue;
}
pr_debug("List set: %s\n", set->name);
if (!cb->args[IPSET_CB_ARG0]) {
/* Start listing: make sure set won't be destroyed */
pr_debug("reference set\n");
__ip_set_get(set);
set->ref++;
}
write_unlock_bh(&ip_set_ref_lock);
nlh = start_msg(skb, NETLINK_CB(cb->skb).portid,
cb->nlh->nlmsg_seq, flags,
IPSET_CMD_LIST);
@ -2012,7 +2028,8 @@ ip_set_net_init(struct net *net)
list = kzalloc(sizeof(struct ip_set *) * inst->ip_set_max, GFP_KERNEL);
if (!list)
return -ENOMEM;
inst->is_deleted = 0;
inst->is_deleted = false;
inst->is_destroyed = false;
rcu_assign_pointer(inst->ip_set_list, list);
return 0;
}
@ -2025,12 +2042,14 @@ ip_set_net_exit(struct net *net)
struct ip_set *set = NULL;
ip_set_id_t i;
inst->is_deleted = 1; /* flag for ip_set_nfnl_put */
inst->is_deleted = true; /* flag for ip_set_nfnl_put */
for (i = 0; i < inst->ip_set_max; i++) {
set = ip_set(inst, i);
if (set != NULL)
ip_set_destroy_set(inst, i);
if (set) {
ip_set(inst, i) = NULL;
ip_set_destroy_set(set);
}
}
kfree(rcu_dereference_protected(inst->ip_set_list, 1));
}