From 834184b1f3a4635efbdfdae5fb437f109f6605fa Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Tue, 15 Nov 2016 21:36:45 +0100 Subject: netfilter: defrag: only register defrag functionality if needed nf_defrag modules for ipv4 and ipv6 export an empty stub function. Any module that needs the defragmentation hooks registered simply 'calls' this empty function to create a phony module dependency -- modprobe will then load the defrag module too. This extends netfilter ipv4/ipv6 defragmentation modules to delay the hook registration until the functionality is requested within a network namespace instead of module load time for all namespaces. Hooks are only un-registered on module unload or when a namespace that used such defrag functionality exits. We have to use struct net for this as the register hooks can be called before netns initialization here from the ipv4/ipv6 conntrack module init path. There is no unregister functionality support, defrag will always be active once it was requested inside a net namespace. The reason is that defrag has impact on nft and iptables rulesets (without defrag we might see framents). Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- net/netfilter/xt_socket.c | 33 ++++++++++++++++++++++++++++----- 1 file changed, 28 insertions(+), 5 deletions(-) (limited to 'net/netfilter/xt_socket.c') diff --git a/net/netfilter/xt_socket.c b/net/netfilter/xt_socket.c index 2198914707f5..770bbec878f1 100644 --- a/net/netfilter/xt_socket.c +++ b/net/netfilter/xt_socket.c @@ -147,9 +147,28 @@ socket_mt6_v1_v2_v3(const struct sk_buff *skb, struct xt_action_param *par) } #endif +static int socket_mt_enable_defrag(struct net *net, int family) +{ + switch (family) { + case NFPROTO_IPV4: + return nf_defrag_ipv4_enable(net); +#ifdef XT_SOCKET_HAVE_IPV6 + case NFPROTO_IPV6: + return nf_defrag_ipv6_enable(net); +#endif + } + WARN_ONCE(1, "Unknown family %d\n", family); + return 0; +} + static int socket_mt_v1_check(const struct xt_mtchk_param *par) { const struct xt_socket_mtinfo1 *info = (struct xt_socket_mtinfo1 *) par->matchinfo; + int err; + + err = socket_mt_enable_defrag(par->net, par->family); + if (err) + return err; if (info->flags & ~XT_SOCKET_FLAGS_V1) { pr_info("unknown flags 0x%x\n", info->flags & ~XT_SOCKET_FLAGS_V1); @@ -161,6 +180,11 @@ static int socket_mt_v1_check(const struct xt_mtchk_param *par) static int socket_mt_v2_check(const struct xt_mtchk_param *par) { const struct xt_socket_mtinfo2 *info = (struct xt_socket_mtinfo2 *) par->matchinfo; + int err; + + err = socket_mt_enable_defrag(par->net, par->family); + if (err) + return err; if (info->flags & ~XT_SOCKET_FLAGS_V2) { pr_info("unknown flags 0x%x\n", info->flags & ~XT_SOCKET_FLAGS_V2); @@ -173,7 +197,11 @@ static int socket_mt_v3_check(const struct xt_mtchk_param *par) { const struct xt_socket_mtinfo3 *info = (struct xt_socket_mtinfo3 *)par->matchinfo; + int err; + err = socket_mt_enable_defrag(par->net, par->family); + if (err) + return err; if (info->flags & ~XT_SOCKET_FLAGS_V3) { pr_info("unknown flags 0x%x\n", info->flags & ~XT_SOCKET_FLAGS_V3); @@ -268,11 +296,6 @@ static struct xt_match socket_mt_reg[] __read_mostly = { static int __init socket_mt_init(void) { - nf_defrag_ipv4_enable(); -#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES) - nf_defrag_ipv6_enable(); -#endif - return xt_register_matches(socket_mt_reg, ARRAY_SIZE(socket_mt_reg)); } -- cgit v1.2.3