From 9c1ba5c809381fb9fb779e2cc22a1c878a269ffb Mon Sep 17 00:00:00 2001 From: Jozsef Kadlecsik Date: Sat, 13 Jun 2015 13:39:38 +0200 Subject: [PATCH] netfilter: ipset: Make sure listing doesn't grab a set which is just being destroyed. 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 --- net/netfilter/ipset/ip_set_core.c | 49 +++++++++++++++++++++---------- 1 file changed, 34 insertions(+), 15 deletions(-) diff --git a/net/netfilter/ipset/ip_set_core.c b/net/netfilter/ipset/ip_set_core.c index 777cac6fd64d..87b4182660ba 100644 --- a/net/netfilter/ipset/ip_set_core.c +++ b/net/netfilter/ipset/ip_set_core.c @@ -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 @@ dump_last: 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 @@ dump_last: */ 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)); } -- 2.20.1