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| author | Eric Dumazet <eric.dumazet@gmail.com> | 2011-07-18 16:08:07 +0200 |
|---|---|---|
| committer | Patrick McHardy <kaber@trash.net> | 2011-07-18 16:08:07 +0200 |
| commit | 6b75e3e8d664a9a1b99d31a7f4976ae70d1d090a (patch) | |
| tree | 940d95c340df22db092062bdaea599e9afc4fcf9 /net/netfilter | |
| parent | 131ad62d8fc06d9d0a5c61d9526876352c2f2bbd (diff) | |
| download | blackbird-op-linux-6b75e3e8d664a9a1b99d31a7f4976ae70d1d090a.tar.gz blackbird-op-linux-6b75e3e8d664a9a1b99d31a7f4976ae70d1d090a.zip | |
netfilter: nfnetlink: add RCU in nfnetlink_rcv_msg()
Goal of this patch is to permit nfnetlink providers not mandate
nfnl_mutex being held while nfnetlink_rcv_msg() calls them.
If struct nfnl_callback contains a non NULL call_rcu(), then
nfnetlink_rcv_msg() will use it instead of call() field, holding
rcu_read_lock instead of nfnl_mutex
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
CC: Florian Westphal <fw@strlen.de>
CC: Eric Leblond <eric@regit.org>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Diffstat (limited to 'net/netfilter')
| -rw-r--r-- | net/netfilter/nfnetlink.c | 40 |
1 files changed, 30 insertions, 10 deletions
diff --git a/net/netfilter/nfnetlink.c b/net/netfilter/nfnetlink.c index b4a4532823e8..1905976b5135 100644 --- a/net/netfilter/nfnetlink.c +++ b/net/netfilter/nfnetlink.c @@ -37,7 +37,7 @@ MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NETFILTER); static char __initdata nfversion[] = "0.30"; -static const struct nfnetlink_subsystem *subsys_table[NFNL_SUBSYS_COUNT]; +static const struct nfnetlink_subsystem __rcu *subsys_table[NFNL_SUBSYS_COUNT]; static DEFINE_MUTEX(nfnl_mutex); void nfnl_lock(void) @@ -59,7 +59,7 @@ int nfnetlink_subsys_register(const struct nfnetlink_subsystem *n) nfnl_unlock(); return -EBUSY; } - subsys_table[n->subsys_id] = n; + rcu_assign_pointer(subsys_table[n->subsys_id], n); nfnl_unlock(); return 0; @@ -71,7 +71,7 @@ int nfnetlink_subsys_unregister(const struct nfnetlink_subsystem *n) nfnl_lock(); subsys_table[n->subsys_id] = NULL; nfnl_unlock(); - + synchronize_rcu(); return 0; } EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister); @@ -83,7 +83,7 @@ static inline const struct nfnetlink_subsystem *nfnetlink_get_subsys(u_int16_t t if (subsys_id >= NFNL_SUBSYS_COUNT) return NULL; - return subsys_table[subsys_id]; + return rcu_dereference(subsys_table[subsys_id]); } static inline const struct nfnl_callback * @@ -139,21 +139,27 @@ static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh) type = nlh->nlmsg_type; replay: + rcu_read_lock(); ss = nfnetlink_get_subsys(type); if (!ss) { #ifdef CONFIG_MODULES - nfnl_unlock(); + rcu_read_unlock(); request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type)); - nfnl_lock(); + rcu_read_lock(); ss = nfnetlink_get_subsys(type); if (!ss) #endif + { + rcu_read_unlock(); return -EINVAL; + } } nc = nfnetlink_find_client(type, ss); - if (!nc) + if (!nc) { + rcu_read_unlock(); return -EINVAL; + } { int min_len = NLMSG_SPACE(sizeof(struct nfgenmsg)); @@ -167,7 +173,23 @@ replay: if (err < 0) return err; - err = nc->call(net->nfnl, skb, nlh, (const struct nlattr **)cda); + if (nc->call_rcu) { + err = nc->call_rcu(net->nfnl, skb, nlh, + (const struct nlattr **)cda); + rcu_read_unlock(); + } else { + rcu_read_unlock(); + nfnl_lock(); + if (rcu_dereference_protected( + subsys_table[NFNL_SUBSYS_ID(type)], + lockdep_is_held(&nfnl_mutex)) != ss || + nfnetlink_find_client(type, ss) != nc) + err = -EAGAIN; + else + err = nc->call(net->nfnl, skb, nlh, + (const struct nlattr **)cda); + nfnl_unlock(); + } if (err == -EAGAIN) goto replay; return err; @@ -176,9 +198,7 @@ replay: static void nfnetlink_rcv(struct sk_buff *skb) { - nfnl_lock(); netlink_rcv_skb(skb, &nfnetlink_rcv_msg); - nfnl_unlock(); } static int __net_init nfnetlink_net_init(struct net *net) |
