From 12f7a505331e6b2754684b509f2ac8f0011ce644 Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Sun, 13 May 2012 21:44:54 +0200 Subject: [PATCH] netfilter: add user-space connection tracking helper infrastructure There are good reasons to supports helpers in user-space instead: * Rapid connection tracking helper development, as developing code in user-space is usually faster. * Reliability: A buggy helper does not crash the kernel. Moreover, we can monitor the helper process and restart it in case of problems. * Security: Avoid complex string matching and mangling in kernel-space running in privileged mode. Going further, we can even think about running user-space helpers as a non-root process. * Extensibility: It allows the development of very specific helpers (most likely non-standard proprietary protocols) that are very likely not to be accepted for mainline inclusion in the form of kernel-space connection tracking helpers. This patch adds the infrastructure to allow the implementation of user-space conntrack helpers by means of the new nfnetlink subsystem `nfnetlink_cthelper' and the existing queueing infrastructure (nfnetlink_queue). I had to add the new hook NF_IP6_PRI_CONNTRACK_HELPER to register ipv[4|6]_helper which results from splitting ipv[4|6]_confirm into two pieces. This change is required not to break NAT sequence adjustment and conntrack confirmation for traffic that is enqueued to our user-space conntrack helpers. Basic operation, in a few steps: 1) Register user-space helper by means of `nfct': nfct helper add ftp inet tcp [ It must be a valid existing helper supported by conntrack-tools ] 2) Add rules to enable the FTP user-space helper which is used to track traffic going to TCP port 21. For locally generated packets: iptables -I OUTPUT -t raw -p tcp --dport 21 -j CT --helper ftp For non-locally generated packets: iptables -I PREROUTING -t raw -p tcp --dport 21 -j CT --helper ftp 3) Run the test conntrackd in helper mode (see example files under doc/helper/conntrackd.conf conntrackd 4) Generate FTP traffic going, if everything is OK, then conntrackd should create expectations (you can check that with `conntrack': conntrack -E expect [NEW] 301 proto=6 src=192.168.1.136 dst=130.89.148.12 sport=0 dport=54037 mask-src=255.255.255.255 mask-dst=255.255.255.255 sport=0 dport=65535 master-src=192.168.1.136 master-dst=130.89.148.12 sport=57127 dport=21 class=0 helper=ftp [DESTROY] 301 proto=6 src=192.168.1.136 dst=130.89.148.12 sport=0 dport=54037 mask-src=255.255.255.255 mask-dst=255.255.255.255 sport=0 dport=65535 master-src=192.168.1.136 master-dst=130.89.148.12 sport=57127 dport=21 class=0 helper=ftp This confirms that our test helper is receiving packets including the conntrack information, and adding expectations in kernel-space. The user-space helper can also store its private tracking information in the conntrack structure in the kernel via the CTA_HELP_INFO. The kernel will consider this a binary blob whose layout is unknown. This information will be included in the information that is transfered to user-space via glue code that integrates nfnetlink_queue and ctnetlink. Signed-off-by: Pablo Neira Ayuso --- include/linux/netfilter/Kbuild | 1 + include/linux/netfilter/nfnetlink.h | 3 +- include/linux/netfilter/nfnetlink_cthelper.h | 55 ++ include/linux/netfilter_ipv4.h | 1 + include/linux/netfilter_ipv6.h | 1 + include/net/netfilter/nf_conntrack_helper.h | 11 + .../netfilter/nf_conntrack_l3proto_ipv4.c | 48 +- .../netfilter/nf_conntrack_l3proto_ipv6.c | 43 +- net/netfilter/Kconfig | 8 + net/netfilter/Makefile | 1 + net/netfilter/nf_conntrack_helper.c | 21 +- net/netfilter/nfnetlink_cthelper.c | 672 ++++++++++++++++++ 12 files changed, 839 insertions(+), 26 deletions(-) create mode 100644 include/linux/netfilter/nfnetlink_cthelper.h create mode 100644 net/netfilter/nfnetlink_cthelper.c diff --git a/include/linux/netfilter/Kbuild b/include/linux/netfilter/Kbuild index 1697036336b6..874ae8f2706b 100644 --- a/include/linux/netfilter/Kbuild +++ b/include/linux/netfilter/Kbuild @@ -10,6 +10,7 @@ header-y += nfnetlink.h header-y += nfnetlink_acct.h header-y += nfnetlink_compat.h header-y += nfnetlink_conntrack.h +header-y += nfnetlink_cthelper.h header-y += nfnetlink_cttimeout.h header-y += nfnetlink_log.h header-y += nfnetlink_queue.h diff --git a/include/linux/netfilter/nfnetlink.h b/include/linux/netfilter/nfnetlink.h index a1048c1587d1..18341cdb2443 100644 --- a/include/linux/netfilter/nfnetlink.h +++ b/include/linux/netfilter/nfnetlink.h @@ -50,7 +50,8 @@ struct nfgenmsg { #define NFNL_SUBSYS_IPSET 6 #define NFNL_SUBSYS_ACCT 7 #define NFNL_SUBSYS_CTNETLINK_TIMEOUT 8 -#define NFNL_SUBSYS_COUNT 9 +#define NFNL_SUBSYS_CTHELPER 9 +#define NFNL_SUBSYS_COUNT 10 #ifdef __KERNEL__ diff --git a/include/linux/netfilter/nfnetlink_cthelper.h b/include/linux/netfilter/nfnetlink_cthelper.h new file mode 100644 index 000000000000..33659f6fad3e --- /dev/null +++ b/include/linux/netfilter/nfnetlink_cthelper.h @@ -0,0 +1,55 @@ +#ifndef _NFNL_CTHELPER_H_ +#define _NFNL_CTHELPER_H_ + +#define NFCT_HELPER_STATUS_DISABLED 0 +#define NFCT_HELPER_STATUS_ENABLED 1 + +enum nfnl_acct_msg_types { + NFNL_MSG_CTHELPER_NEW, + NFNL_MSG_CTHELPER_GET, + NFNL_MSG_CTHELPER_DEL, + NFNL_MSG_CTHELPER_MAX +}; + +enum nfnl_cthelper_type { + NFCTH_UNSPEC, + NFCTH_NAME, + NFCTH_TUPLE, + NFCTH_QUEUE_NUM, + NFCTH_POLICY, + NFCTH_PRIV_DATA_LEN, + NFCTH_STATUS, + __NFCTH_MAX +}; +#define NFCTH_MAX (__NFCTH_MAX - 1) + +enum nfnl_cthelper_policy_type { + NFCTH_POLICY_SET_UNSPEC, + NFCTH_POLICY_SET_NUM, + NFCTH_POLICY_SET, + NFCTH_POLICY_SET1 = NFCTH_POLICY_SET, + NFCTH_POLICY_SET2, + NFCTH_POLICY_SET3, + NFCTH_POLICY_SET4, + __NFCTH_POLICY_SET_MAX +}; +#define NFCTH_POLICY_SET_MAX (__NFCTH_POLICY_SET_MAX - 1) + +enum nfnl_cthelper_pol_type { + NFCTH_POLICY_UNSPEC, + NFCTH_POLICY_NAME, + NFCTH_POLICY_EXPECT_MAX, + NFCTH_POLICY_EXPECT_TIMEOUT, + __NFCTH_POLICY_MAX +}; +#define NFCTH_POLICY_MAX (__NFCTH_POLICY_MAX - 1) + +enum nfnl_cthelper_tuple_type { + NFCTH_TUPLE_UNSPEC, + NFCTH_TUPLE_L3PROTONUM, + NFCTH_TUPLE_L4PROTONUM, + __NFCTH_TUPLE_MAX, +}; +#define NFCTH_TUPLE_MAX (__NFCTH_TUPLE_MAX - 1) + +#endif /* _NFNL_CTHELPER_H */ diff --git a/include/linux/netfilter_ipv4.h b/include/linux/netfilter_ipv4.h index fa0946c549d3..e2b12801378d 100644 --- a/include/linux/netfilter_ipv4.h +++ b/include/linux/netfilter_ipv4.h @@ -66,6 +66,7 @@ enum nf_ip_hook_priorities { NF_IP_PRI_SECURITY = 50, NF_IP_PRI_NAT_SRC = 100, NF_IP_PRI_SELINUX_LAST = 225, + NF_IP_PRI_CONNTRACK_HELPER = 300, NF_IP_PRI_CONNTRACK_CONFIRM = INT_MAX, NF_IP_PRI_LAST = INT_MAX, }; diff --git a/include/linux/netfilter_ipv6.h b/include/linux/netfilter_ipv6.h index 57c025127f1d..7c8a513ce7a3 100644 --- a/include/linux/netfilter_ipv6.h +++ b/include/linux/netfilter_ipv6.h @@ -71,6 +71,7 @@ enum nf_ip6_hook_priorities { NF_IP6_PRI_SECURITY = 50, NF_IP6_PRI_NAT_SRC = 100, NF_IP6_PRI_SELINUX_LAST = 225, + NF_IP6_PRI_CONNTRACK_HELPER = 300, NF_IP6_PRI_LAST = INT_MAX, }; diff --git a/include/net/netfilter/nf_conntrack_helper.h b/include/net/netfilter/nf_conntrack_helper.h index 84b24c3a3834..9aad956d1008 100644 --- a/include/net/netfilter/nf_conntrack_helper.h +++ b/include/net/netfilter/nf_conntrack_helper.h @@ -15,6 +15,11 @@ struct module; +enum nf_ct_helper_flags { + NF_CT_HELPER_F_USERSPACE = (1 << 0), + NF_CT_HELPER_F_CONFIGURED = (1 << 1), +}; + #define NF_CT_HELPER_NAME_LEN 16 struct nf_conntrack_helper { @@ -42,6 +47,9 @@ struct nf_conntrack_helper { int (*from_nlattr)(struct nlattr *attr, struct nf_conn *ct); int (*to_nlattr)(struct sk_buff *skb, const struct nf_conn *ct); unsigned int expect_class_max; + + unsigned int flags; + unsigned int queue_num; /* For user-space helpers. */ }; extern struct nf_conntrack_helper * @@ -96,4 +104,7 @@ nf_ct_helper_expectfn_find_by_name(const char *name); struct nf_ct_helper_expectfn * nf_ct_helper_expectfn_find_by_symbol(const void *symbol); +extern struct hlist_head *nf_ct_helper_hash; +extern unsigned int nf_ct_helper_hsize; + #endif /*_NF_CONNTRACK_HELPER_H*/ diff --git a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c index d79b961a8009..e7ff2dcab6ce 100644 --- a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c +++ b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c @@ -95,11 +95,11 @@ static int ipv4_get_l4proto(const struct sk_buff *skb, unsigned int nhoff, return NF_ACCEPT; } -static unsigned int ipv4_confirm(unsigned int hooknum, - struct sk_buff *skb, - const struct net_device *in, - const struct net_device *out, - int (*okfn)(struct sk_buff *)) +static unsigned int ipv4_helper(unsigned int hooknum, + struct sk_buff *skb, + const struct net_device *in, + const struct net_device *out, + int (*okfn)(struct sk_buff *)) { struct nf_conn *ct; enum ip_conntrack_info ctinfo; @@ -110,24 +110,38 @@ static unsigned int ipv4_confirm(unsigned int hooknum, /* This is where we call the helper: as the packet goes out. */ ct = nf_ct_get(skb, &ctinfo); if (!ct || ctinfo == IP_CT_RELATED_REPLY) - goto out; + return NF_ACCEPT; help = nfct_help(ct); if (!help) - goto out; + return NF_ACCEPT; /* rcu_read_lock()ed by nf_hook_slow */ helper = rcu_dereference(help->helper); if (!helper) - goto out; + return NF_ACCEPT; ret = helper->help(skb, skb_network_offset(skb) + ip_hdrlen(skb), ct, ctinfo); - if (ret != NF_ACCEPT) { + if (ret != NF_ACCEPT && (ret & NF_VERDICT_MASK) != NF_QUEUE) { nf_log_packet(NFPROTO_IPV4, hooknum, skb, in, out, NULL, "nf_ct_%s: dropping packet", helper->name); - return ret; } + return ret; +} + +static unsigned int ipv4_confirm(unsigned int hooknum, + struct sk_buff *skb, + const struct net_device *in, + const struct net_device *out, + int (*okfn)(struct sk_buff *)) +{ + struct nf_conn *ct; + enum ip_conntrack_info ctinfo; + + ct = nf_ct_get(skb, &ctinfo); + if (!ct || ctinfo == IP_CT_RELATED_REPLY) + goto out; /* adjust seqs for loopback traffic only in outgoing direction */ if (test_bit(IPS_SEQ_ADJUST_BIT, &ct->status) && @@ -184,6 +198,13 @@ static struct nf_hook_ops ipv4_conntrack_ops[] __read_mostly = { .hooknum = NF_INET_LOCAL_OUT, .priority = NF_IP_PRI_CONNTRACK, }, + { + .hook = ipv4_helper, + .owner = THIS_MODULE, + .pf = NFPROTO_IPV4, + .hooknum = NF_INET_POST_ROUTING, + .priority = NF_IP_PRI_CONNTRACK_HELPER, + }, { .hook = ipv4_confirm, .owner = THIS_MODULE, @@ -191,6 +212,13 @@ static struct nf_hook_ops ipv4_conntrack_ops[] __read_mostly = { .hooknum = NF_INET_POST_ROUTING, .priority = NF_IP_PRI_CONNTRACK_CONFIRM, }, + { + .hook = ipv4_helper, + .owner = THIS_MODULE, + .pf = NFPROTO_IPV4, + .hooknum = NF_INET_LOCAL_IN, + .priority = NF_IP_PRI_CONNTRACK_HELPER, + }, { .hook = ipv4_confirm, .owner = THIS_MODULE, diff --git a/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c b/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c index fca10da80ea7..4794f96cf2e0 100644 --- a/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c +++ b/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c @@ -143,11 +143,11 @@ static int ipv6_get_l4proto(const struct sk_buff *skb, unsigned int nhoff, return NF_ACCEPT; } -static unsigned int ipv6_confirm(unsigned int hooknum, - struct sk_buff *skb, - const struct net_device *in, - const struct net_device *out, - int (*okfn)(struct sk_buff *)) +static unsigned int ipv6_helper(unsigned int hooknum, + struct sk_buff *skb, + const struct net_device *in, + const struct net_device *out, + int (*okfn)(struct sk_buff *)) { struct nf_conn *ct; const struct nf_conn_help *help; @@ -161,15 +161,15 @@ static unsigned int ipv6_confirm(unsigned int hooknum, /* This is where we call the helper: as the packet goes out. */ ct = nf_ct_get(skb, &ctinfo); if (!ct || ctinfo == IP_CT_RELATED_REPLY) - goto out; + return NF_ACCEPT; help = nfct_help(ct); if (!help) - goto out; + return NF_ACCEPT; /* rcu_read_lock()ed by nf_hook_slow */ helper = rcu_dereference(help->helper); if (!helper) - goto out; + return NF_ACCEPT; protoff = nf_ct_ipv6_skip_exthdr(skb, extoff, &pnum, skb->len - extoff); @@ -179,12 +179,19 @@ static unsigned int ipv6_confirm(unsigned int hooknum, } ret = helper->help(skb, protoff, ct, ctinfo); - if (ret != NF_ACCEPT) { + if (ret != NF_ACCEPT && (ret & NF_VERDICT_MASK) != NF_QUEUE) { nf_log_packet(NFPROTO_IPV6, hooknum, skb, in, out, NULL, "nf_ct_%s: dropping packet", helper->name); - return ret; } -out: + return ret; +} + +static unsigned int ipv6_confirm(unsigned int hooknum, + struct sk_buff *skb, + const struct net_device *in, + const struct net_device *out, + int (*okfn)(struct sk_buff *)) +{ /* We've seen it coming out the other side: confirm it */ return nf_conntrack_confirm(skb); } @@ -253,6 +260,13 @@ static struct nf_hook_ops ipv6_conntrack_ops[] __read_mostly = { .hooknum = NF_INET_LOCAL_OUT, .priority = NF_IP6_PRI_CONNTRACK, }, + { + .hook = ipv6_helper, + .owner = THIS_MODULE, + .pf = NFPROTO_IPV6, + .hooknum = NF_INET_POST_ROUTING, + .priority = NF_IP6_PRI_CONNTRACK_HELPER, + }, { .hook = ipv6_confirm, .owner = THIS_MODULE, @@ -260,6 +274,13 @@ static struct nf_hook_ops ipv6_conntrack_ops[] __read_mostly = { .hooknum = NF_INET_POST_ROUTING, .priority = NF_IP6_PRI_LAST, }, + { + .hook = ipv6_helper, + .owner = THIS_MODULE, + .pf = NFPROTO_IPV6, + .hooknum = NF_INET_LOCAL_IN, + .priority = NF_IP6_PRI_CONNTRACK_HELPER, + }, { .hook = ipv6_confirm, .owner = THIS_MODULE, diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig index 209c1ed43368..aae6c628991d 100644 --- a/net/netfilter/Kconfig +++ b/net/netfilter/Kconfig @@ -12,6 +12,14 @@ tristate "Netfilter NFACCT over NFNETLINK interface" If this option is enabled, the kernel will include support for extended accounting via NFNETLINK. +config NETFILTER_NETLINK_CTHELPER +tristate "Netfilter CTHELPER over NFNETLINK interface" + depends on NETFILTER_ADVANCED + select NETFILTER_NETLINK + help + If this option is enabled, the kernel will include support + for user-space connection tracking helpers via NFNETLINK. + config NETFILTER_NETLINK_QUEUE tristate "Netfilter NFQUEUE over NFNETLINK interface" depends on NETFILTER_ADVANCED diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile index 4e7960cc7b97..2f3bc0f647ba 100644 --- a/net/netfilter/Makefile +++ b/net/netfilter/Makefile @@ -9,6 +9,7 @@ obj-$(CONFIG_NETFILTER) = netfilter.o obj-$(CONFIG_NETFILTER_NETLINK) += nfnetlink.o obj-$(CONFIG_NETFILTER_NETLINK_ACCT) += nfnetlink_acct.o +obj-$(CONFIG_NETFILTER_NETLINK_CTHELPER) += nfnetlink_cthelper.o obj-$(CONFIG_NETFILTER_NETLINK_QUEUE) += nfnetlink_queue.o obj-$(CONFIG_NETFILTER_NETLINK_LOG) += nfnetlink_log.o diff --git a/net/netfilter/nf_conntrack_helper.c b/net/netfilter/nf_conntrack_helper.c index 9c18ecb0ab81..2918ec2e4509 100644 --- a/net/netfilter/nf_conntrack_helper.c +++ b/net/netfilter/nf_conntrack_helper.c @@ -30,8 +30,10 @@ #include static DEFINE_MUTEX(nf_ct_helper_mutex); -static struct hlist_head *nf_ct_helper_hash __read_mostly; -static unsigned int nf_ct_helper_hsize __read_mostly; +struct hlist_head *nf_ct_helper_hash __read_mostly; +EXPORT_SYMBOL_GPL(nf_ct_helper_hash); +unsigned int nf_ct_helper_hsize __read_mostly; +EXPORT_SYMBOL_GPL(nf_ct_helper_hsize); static unsigned int nf_ct_helper_count __read_mostly; static bool nf_ct_auto_assign_helper __read_mostly = true; @@ -322,6 +324,9 @@ EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_symbol); int nf_conntrack_helper_register(struct nf_conntrack_helper *me) { + int ret = 0; + struct nf_conntrack_helper *cur; + struct hlist_node *n; unsigned int h = helper_hash(&me->tuple); BUG_ON(me->expect_policy == NULL); @@ -329,11 +334,19 @@ int nf_conntrack_helper_register(struct nf_conntrack_helper *me) BUG_ON(strlen(me->name) > NF_CT_HELPER_NAME_LEN - 1); mutex_lock(&nf_ct_helper_mutex); + hlist_for_each_entry(cur, n, &nf_ct_helper_hash[h], hnode) { + if (strncmp(cur->name, me->name, NF_CT_HELPER_NAME_LEN) == 0 && + cur->tuple.src.l3num == me->tuple.src.l3num && + cur->tuple.dst.protonum == me->tuple.dst.protonum) { + ret = -EEXIST; + goto out; + } + } hlist_add_head_rcu(&me->hnode, &nf_ct_helper_hash[h]); nf_ct_helper_count++; +out: mutex_unlock(&nf_ct_helper_mutex); - - return 0; + return ret; } EXPORT_SYMBOL_GPL(nf_conntrack_helper_register); diff --git a/net/netfilter/nfnetlink_cthelper.c b/net/netfilter/nfnetlink_cthelper.c new file mode 100644 index 000000000000..d6836193d479 --- /dev/null +++ b/net/netfilter/nfnetlink_cthelper.c @@ -0,0 +1,672 @@ +/* + * (C) 2012 Pablo Neira Ayuso + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation (or any later at your option). + * + * This software has been sponsored by Vyatta Inc. + */ +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include +#include + +#include +#include +#include + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Pablo Neira Ayuso "); +MODULE_DESCRIPTION("nfnl_cthelper: User-space connection tracking helpers"); + +static int +nfnl_userspace_cthelper(struct sk_buff *skb, unsigned int protoff, + struct nf_conn *ct, enum ip_conntrack_info ctinfo) +{ + const struct nf_conn_help *help; + struct nf_conntrack_helper *helper; + + help = nfct_help(ct); + if (help == NULL) + return NF_DROP; + + /* rcu_read_lock()ed by nf_hook_slow */ + helper = rcu_dereference(help->helper); + if (helper == NULL) + return NF_DROP; + + /* This is an user-space helper not yet configured, skip. */ + if ((helper->flags & + (NF_CT_HELPER_F_USERSPACE | NF_CT_HELPER_F_CONFIGURED)) == + NF_CT_HELPER_F_USERSPACE) + return NF_ACCEPT; + + /* If the user-space helper is not available, don't block traffic. */ + return NF_QUEUE_NR(helper->queue_num) | NF_VERDICT_FLAG_QUEUE_BYPASS; +} + +static const struct nla_policy nfnl_cthelper_tuple_pol[NFCTH_TUPLE_MAX+1] = { + [NFCTH_TUPLE_L3PROTONUM] = { .type = NLA_U16, }, + [NFCTH_TUPLE_L4PROTONUM] = { .type = NLA_U8, }, +}; + +static int +nfnl_cthelper_parse_tuple(struct nf_conntrack_tuple *tuple, + const struct nlattr *attr) +{ + struct nlattr *tb[NFCTH_TUPLE_MAX+1]; + + nla_parse_nested(tb, NFCTH_TUPLE_MAX, attr, nfnl_cthelper_tuple_pol); + + if (!tb[NFCTH_TUPLE_L3PROTONUM] || !tb[NFCTH_TUPLE_L4PROTONUM]) + return -EINVAL; + + tuple->src.l3num = ntohs(nla_get_u16(tb[NFCTH_TUPLE_L3PROTONUM])); + tuple->dst.protonum = nla_get_u8(tb[NFCTH_TUPLE_L4PROTONUM]); + + return 0; +} + +static int +nfnl_cthelper_from_nlattr(struct nlattr *attr, struct nf_conn *ct) +{ + const struct nf_conn_help *help = nfct_help(ct); + + if (help->helper->data_len == 0) + return -EINVAL; + + memcpy(&help->data, nla_data(attr), help->helper->data_len); + return 0; +} + +static int +nfnl_cthelper_to_nlattr(struct sk_buff *skb, const struct nf_conn *ct) +{ + const struct nf_conn_help *help = nfct_help(ct); + + if (help->helper->data_len && + nla_put(skb, CTA_HELP_INFO, help->helper->data_len, &help->data)) + goto nla_put_failure; + + return 0; + +nla_put_failure: + return -ENOSPC; +} + +static const struct nla_policy nfnl_cthelper_expect_pol[NFCTH_POLICY_MAX+1] = { + [NFCTH_POLICY_NAME] = { .type = NLA_NUL_STRING, + .len = NF_CT_HELPER_NAME_LEN-1 }, + [NFCTH_POLICY_EXPECT_MAX] = { .type = NLA_U32, }, + [NFCTH_POLICY_EXPECT_TIMEOUT] = { .type = NLA_U32, }, +}; + +static int +nfnl_cthelper_expect_policy(struct nf_conntrack_expect_policy *expect_policy, + const struct nlattr *attr) +{ + struct nlattr *tb[NFCTH_POLICY_MAX+1]; + + nla_parse_nested(tb, NFCTH_POLICY_MAX, attr, nfnl_cthelper_expect_pol); + + if (!tb[NFCTH_POLICY_NAME] || + !tb[NFCTH_POLICY_EXPECT_MAX] || + !tb[NFCTH_POLICY_EXPECT_TIMEOUT]) + return -EINVAL; + + strncpy(expect_policy->name, + nla_data(tb[NFCTH_POLICY_NAME]), NF_CT_HELPER_NAME_LEN); + expect_policy->max_expected = + ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_MAX])); + expect_policy->timeout = + ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_TIMEOUT])); + + return 0; +} + +static const struct nla_policy +nfnl_cthelper_expect_policy_set[NFCTH_POLICY_SET_MAX+1] = { + [NFCTH_POLICY_SET_NUM] = { .type = NLA_U32, }, +}; + +static int +nfnl_cthelper_parse_expect_policy(struct nf_conntrack_helper *helper, + const struct nlattr *attr) +{ + int i, ret; + struct nf_conntrack_expect_policy *expect_policy; + struct nlattr *tb[NFCTH_POLICY_SET_MAX+1]; + + nla_parse_nested(tb, NFCTH_POLICY_SET_MAX, attr, + nfnl_cthelper_expect_policy_set); + + if (!tb[NFCTH_POLICY_SET_NUM]) + return -EINVAL; + + helper->expect_class_max = + ntohl(nla_get_be32(tb[NFCTH_POLICY_SET_NUM])); + + if (helper->expect_class_max != 0 && + helper->expect_class_max > NF_CT_MAX_EXPECT_CLASSES) + return -EOVERFLOW; + + expect_policy = kzalloc(sizeof(struct nf_conntrack_expect_policy) * + helper->expect_class_max, GFP_KERNEL); + if (expect_policy == NULL) + return -ENOMEM; + + for (i=0; iexpect_class_max; i++) { + if (!tb[NFCTH_POLICY_SET+i]) + goto err; + + ret = nfnl_cthelper_expect_policy(&expect_policy[i], + tb[NFCTH_POLICY_SET+i]); + if (ret < 0) + goto err; + } + helper->expect_policy = expect_policy; + return 0; +err: + kfree(expect_policy); + return -EINVAL; +} + +static int +nfnl_cthelper_create(const struct nlattr * const tb[], + struct nf_conntrack_tuple *tuple) +{ + struct nf_conntrack_helper *helper; + int ret; + + if (!tb[NFCTH_TUPLE] || !tb[NFCTH_POLICY] || !tb[NFCTH_PRIV_DATA_LEN]) + return -EINVAL; + + helper = kzalloc(sizeof(struct nf_conntrack_helper), GFP_KERNEL); + if (helper == NULL) + return -ENOMEM; + + ret = nfnl_cthelper_parse_expect_policy(helper, tb[NFCTH_POLICY]); + if (ret < 0) + goto err; + + strncpy(helper->name, nla_data(tb[NFCTH_NAME]), NF_CT_HELPER_NAME_LEN); + helper->data_len = ntohl(nla_get_be32(tb[NFCTH_PRIV_DATA_LEN])); + helper->flags |= NF_CT_HELPER_F_USERSPACE; + memcpy(&helper->tuple, tuple, sizeof(struct nf_conntrack_tuple)); + + helper->me = THIS_MODULE; + helper->help = nfnl_userspace_cthelper; + helper->from_nlattr = nfnl_cthelper_from_nlattr; + helper->to_nlattr = nfnl_cthelper_to_nlattr; + + /* Default to queue number zero, this can be updated at any time. */ + if (tb[NFCTH_QUEUE_NUM]) + helper->queue_num = ntohl(nla_get_be32(tb[NFCTH_QUEUE_NUM])); + + if (tb[NFCTH_STATUS]) { + int status = ntohl(nla_get_be32(tb[NFCTH_STATUS])); + + switch(status) { + case NFCT_HELPER_STATUS_ENABLED: + helper->flags |= NF_CT_HELPER_F_CONFIGURED; + break; + case NFCT_HELPER_STATUS_DISABLED: + helper->flags &= ~NF_CT_HELPER_F_CONFIGURED; + break; + } + } + + ret = nf_conntrack_helper_register(helper); + if (ret < 0) + goto err; + + return 0; +err: + kfree(helper); + return ret; +} + +static int +nfnl_cthelper_update(const struct nlattr * const tb[], + struct nf_conntrack_helper *helper) +{ + int ret; + + if (tb[NFCTH_PRIV_DATA_LEN]) + return -EBUSY; + + if (tb[NFCTH_POLICY]) { + ret = nfnl_cthelper_parse_expect_policy(helper, + tb[NFCTH_POLICY]); + if (ret < 0) + return ret; + } + if (tb[NFCTH_QUEUE_NUM]) + helper->queue_num = ntohl(nla_get_be32(tb[NFCTH_QUEUE_NUM])); + + if (tb[NFCTH_STATUS]) { + int status = ntohl(nla_get_be32(tb[NFCTH_STATUS])); + + switch(status) { + case NFCT_HELPER_STATUS_ENABLED: + helper->flags |= NF_CT_HELPER_F_CONFIGURED; + break; + case NFCT_HELPER_STATUS_DISABLED: + helper->flags &= ~NF_CT_HELPER_F_CONFIGURED; + break; + } + } + return 0; +} + +static int +nfnl_cthelper_new(struct sock *nfnl, struct sk_buff *skb, + const struct nlmsghdr *nlh, const struct nlattr * const tb[]) +{ + const char *helper_name; + struct nf_conntrack_helper *cur, *helper = NULL; + struct nf_conntrack_tuple tuple; + struct hlist_node *n; + int ret = 0, i; + + if (!tb[NFCTH_NAME] || !tb[NFCTH_TUPLE]) + return -EINVAL; + + helper_name = nla_data(tb[NFCTH_NAME]); + + ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]); + if (ret < 0) + return ret; + + rcu_read_lock(); + for (i = 0; i < nf_ct_helper_hsize && !helper; i++) { + hlist_for_each_entry_rcu(cur, n, &nf_ct_helper_hash[i], hnode) { + + /* skip non-userspace conntrack helpers. */ + if (!(cur->flags & NF_CT_HELPER_F_USERSPACE)) + continue; + + if (strncmp(cur->name, helper_name, + NF_CT_HELPER_NAME_LEN) != 0) + continue; + + if ((tuple.src.l3num != cur->tuple.src.l3num || + tuple.dst.protonum != cur->tuple.dst.protonum)) + continue; + + if (nlh->nlmsg_flags & NLM_F_EXCL) { + ret = -EEXIST; + goto err; + } + helper = cur; + break; + } + } + rcu_read_unlock(); + + if (helper == NULL) + ret = nfnl_cthelper_create(tb, &tuple); + else + ret = nfnl_cthelper_update(tb, helper); + + return ret; +err: + rcu_read_unlock(); + return ret; +} + +static int +nfnl_cthelper_dump_tuple(struct sk_buff *skb, + struct nf_conntrack_helper *helper) +{ + struct nlattr *nest_parms; + + nest_parms = nla_nest_start(skb, NFCTH_TUPLE | NLA_F_NESTED); + if (nest_parms == NULL) + goto nla_put_failure; + + if (nla_put_be16(skb, NFCTH_TUPLE_L3PROTONUM, + htons(helper->tuple.src.l3num))) + goto nla_put_failure; + + if (nla_put_u8(skb, NFCTH_TUPLE_L4PROTONUM, helper->tuple.dst.protonum)) + goto nla_put_failure; + + nla_nest_end(skb, nest_parms); + return 0; + +nla_put_failure: + return -1; +} + +static int +nfnl_cthelper_dump_policy(struct sk_buff *skb, + struct nf_conntrack_helper *helper) +{ + int i; + struct nlattr *nest_parms1, *nest_parms2; + + nest_parms1 = nla_nest_start(skb, NFCTH_POLICY | NLA_F_NESTED); + if (nest_parms1 == NULL) + goto nla_put_failure; + + if (nla_put_be32(skb, NFCTH_POLICY_SET_NUM, + htonl(helper->expect_class_max))) + goto nla_put_failure; + + for (i=0; iexpect_class_max; i++) { + nest_parms2 = nla_nest_start(skb, + (NFCTH_POLICY_SET+i) | NLA_F_NESTED); + if (nest_parms2 == NULL) + goto nla_put_failure; + + if (nla_put_string(skb, NFCTH_POLICY_NAME, + helper->expect_policy[i].name)) + goto nla_put_failure; + + if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_MAX, + htonl(helper->expect_policy[i].max_expected))) + goto nla_put_failure; + + if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_TIMEOUT, + htonl(helper->expect_policy[i].timeout))) + goto nla_put_failure; + + nla_nest_end(skb, nest_parms2); + } + nla_nest_end(skb, nest_parms1); + return 0; + +nla_put_failure: + return -1; +} + +static int +nfnl_cthelper_fill_info(struct sk_buff *skb, u32 pid, u32 seq, u32 type, + int event, struct nf_conntrack_helper *helper) +{ + struct nlmsghdr *nlh; + struct nfgenmsg *nfmsg; + unsigned int flags = pid ? NLM_F_MULTI : 0; + int status; + + event |= NFNL_SUBSYS_CTHELPER << 8; + nlh = nlmsg_put(skb, pid, seq, event, sizeof(*nfmsg), flags); + if (nlh == NULL) + goto nlmsg_failure; + + nfmsg = nlmsg_data(nlh); + nfmsg->nfgen_family = AF_UNSPEC; + nfmsg->version = NFNETLINK_V0; + nfmsg->res_id = 0; + + if (nla_put_string(skb, NFCTH_NAME, helper->name)) + goto nla_put_failure; + + if (nla_put_be32(skb, NFCTH_QUEUE_NUM, htonl(helper->queue_num))) + goto nla_put_failure; + + if (nfnl_cthelper_dump_tuple(skb, helper) < 0) + goto nla_put_failure; + + if (nfnl_cthelper_dump_policy(skb, helper) < 0) + goto nla_put_failure; + + if (nla_put_be32(skb, NFCTH_PRIV_DATA_LEN, htonl(helper->data_len))) + goto nla_put_failure; + + if (helper->flags & NF_CT_HELPER_F_CONFIGURED) + status = NFCT_HELPER_STATUS_ENABLED; + else + status = NFCT_HELPER_STATUS_DISABLED; + + if (nla_put_be32(skb, NFCTH_STATUS, htonl(status))) + goto nla_put_failure; + + nlmsg_end(skb, nlh); + return skb->len; + +nlmsg_failure: +nla_put_failure: + nlmsg_cancel(skb, nlh); + return -1; +} + +static int +nfnl_cthelper_dump_table(struct sk_buff *skb, struct netlink_callback *cb) +{ + struct nf_conntrack_helper *cur, *last; + struct hlist_node *n; + + rcu_read_lock(); + last = (struct nf_conntrack_helper *)cb->args[1]; + for (; cb->args[0] < nf_ct_helper_hsize; cb->args[0]++) { +restart: + hlist_for_each_entry_rcu(cur, n, + &nf_ct_helper_hash[cb->args[0]], hnode) { + + /* skip non-userspace conntrack helpers. */ + if (!(cur->flags & NF_CT_HELPER_F_USERSPACE)) + continue; + + if (cb->args[1]) { + if (cur != last) + continue; + cb->args[1] = 0; + } + if (nfnl_cthelper_fill_info(skb, + NETLINK_CB(cb->skb).pid, + cb->nlh->nlmsg_seq, + NFNL_MSG_TYPE(cb->nlh->nlmsg_type), + NFNL_MSG_CTHELPER_NEW, cur) < 0) { + cb->args[1] = (unsigned long)cur; + goto out; + } + } + } + if (cb->args[1]) { + cb->args[1] = 0; + goto restart; + } +out: + rcu_read_unlock(); + return skb->len; +} + +static int +nfnl_cthelper_get(struct sock *nfnl, struct sk_buff *skb, + const struct nlmsghdr *nlh, const struct nlattr * const tb[]) +{ + int ret = -ENOENT, i; + struct nf_conntrack_helper *cur; + struct hlist_node *n; + struct sk_buff *skb2; + char *helper_name = NULL; + struct nf_conntrack_tuple tuple; + bool tuple_set = false; + + if (nlh->nlmsg_flags & NLM_F_DUMP) { + struct netlink_dump_control c = { + .dump = nfnl_cthelper_dump_table, + }; + return netlink_dump_start(nfnl, skb, nlh, &c); + } + + if (tb[NFCTH_NAME]) + helper_name = nla_data(tb[NFCTH_NAME]); + + if (tb[NFCTH_TUPLE]) { + ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]); + if (ret < 0) + return ret; + + tuple_set = true; + } + + for (i = 0; i < nf_ct_helper_hsize; i++) { + hlist_for_each_entry_rcu(cur, n, &nf_ct_helper_hash[i], hnode) { + + /* skip non-userspace conntrack helpers. */ + if (!(cur->flags & NF_CT_HELPER_F_USERSPACE)) + continue; + + if (helper_name && strncmp(cur->name, helper_name, + NF_CT_HELPER_NAME_LEN) != 0) { + continue; + } + if (tuple_set && + (tuple.src.l3num != cur->tuple.src.l3num || + tuple.dst.protonum != cur->tuple.dst.protonum)) + continue; + + skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL); + if (skb2 == NULL) { + ret = -ENOMEM; + break; + } + + ret = nfnl_cthelper_fill_info(skb2, NETLINK_CB(skb).pid, + nlh->nlmsg_seq, + NFNL_MSG_TYPE(nlh->nlmsg_type), + NFNL_MSG_CTHELPER_NEW, cur); + if (ret <= 0) { + kfree_skb(skb2); + break; + } + + ret = netlink_unicast(nfnl, skb2, NETLINK_CB(skb).pid, + MSG_DONTWAIT); + if (ret > 0) + ret = 0; + + /* this avoids a loop in nfnetlink. */ + return ret == -EAGAIN ? -ENOBUFS : ret; + } + } + return ret; +} + +static int +nfnl_cthelper_del(struct sock *nfnl, struct sk_buff *skb, + const struct nlmsghdr *nlh, const struct nlattr * const tb[]) +{ + char *helper_name = NULL; + struct nf_conntrack_helper *cur; + struct hlist_node *n, *tmp; + struct nf_conntrack_tuple tuple; + bool tuple_set = false, found = false; + int i, j = 0, ret; + + if (tb[NFCTH_NAME]) + helper_name = nla_data(tb[NFCTH_NAME]); + + if (tb[NFCTH_TUPLE]) { + ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]); + if (ret < 0) + return ret; + + tuple_set = true; + } + + for (i = 0; i < nf_ct_helper_hsize; i++) { + hlist_for_each_entry_safe(cur, n, tmp, &nf_ct_helper_hash[i], + hnode) { + /* skip non-userspace conntrack helpers. */ + if (!(cur->flags & NF_CT_HELPER_F_USERSPACE)) + continue; + + j++; + + if (helper_name && strncmp(cur->name, helper_name, + NF_CT_HELPER_NAME_LEN) != 0) { + continue; + } + if (tuple_set && + (tuple.src.l3num != cur->tuple.src.l3num || + tuple.dst.protonum != cur->tuple.dst.protonum)) + continue; + + found = true; + nf_conntrack_helper_unregister(cur); + } + } + /* Make sure we return success if we flush and there is no helpers */ + return (found || j == 0) ? 0 : -ENOENT; +} + +static const struct nla_policy nfnl_cthelper_policy[NFCTH_MAX+1] = { + [NFCTH_NAME] = { .type = NLA_NUL_STRING, + .len = NF_CT_HELPER_NAME_LEN-1 }, + [NFCTH_QUEUE_NUM] = { .type = NLA_U32, }, +}; + +static const struct nfnl_callback nfnl_cthelper_cb[NFNL_MSG_CTHELPER_MAX] = { + [NFNL_MSG_CTHELPER_NEW] = { .call = nfnl_cthelper_new, + .attr_count = NFCTH_MAX, + .policy = nfnl_cthelper_policy }, + [NFNL_MSG_CTHELPER_GET] = { .call = nfnl_cthelper_get, + .attr_count = NFCTH_MAX, + .policy = nfnl_cthelper_policy }, + [NFNL_MSG_CTHELPER_DEL] = { .call = nfnl_cthelper_del, + .attr_count = NFCTH_MAX, + .policy = nfnl_cthelper_policy }, +}; + +static const struct nfnetlink_subsystem nfnl_cthelper_subsys = { + .name = "cthelper", + .subsys_id = NFNL_SUBSYS_CTHELPER, + .cb_count = NFNL_MSG_CTHELPER_MAX, + .cb = nfnl_cthelper_cb, +}; + +MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_CTHELPER); + +static int __init nfnl_cthelper_init(void) +{ + int ret; + + ret = nfnetlink_subsys_register(&nfnl_cthelper_subsys); + if (ret < 0) { + pr_err("nfnl_cthelper: cannot register with nfnetlink.\n"); + goto err_out; + } + return 0; +err_out: + return ret; +} + +static void __exit nfnl_cthelper_exit(void) +{ + struct nf_conntrack_helper *cur; + struct hlist_node *n, *tmp; + int i; + + nfnetlink_subsys_unregister(&nfnl_cthelper_subsys); + + for (i=0; iflags & NF_CT_HELPER_F_USERSPACE)) + continue; + + nf_conntrack_helper_unregister(cur); + } + } +} + +module_init(nfnl_cthelper_init); +module_exit(nfnl_cthelper_exit); -- 2.20.1