From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001 From: André Fabian Silva Delgado Date: Wed, 5 Aug 2015 17:04:01 -0300 Subject: Initial import --- net/netfilter/nf_conntrack_helper.c | 502 ++++++++++++++++++++++++++++++++++++ 1 file changed, 502 insertions(+) create mode 100644 net/netfilter/nf_conntrack_helper.c (limited to 'net/netfilter/nf_conntrack_helper.c') diff --git a/net/netfilter/nf_conntrack_helper.c b/net/netfilter/nf_conntrack_helper.c new file mode 100644 index 000000000..bd9d31537 --- /dev/null +++ b/net/netfilter/nf_conntrack_helper.c @@ -0,0 +1,502 @@ +/* Helper handling for netfilter. */ + +/* (C) 1999-2001 Paul `Rusty' Russell + * (C) 2002-2006 Netfilter Core Team + * (C) 2003,2004 USAGI/WIDE Project + * (C) 2006-2012 Patrick McHardy + * + * 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. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include +#include +#include +#include +#include +#include + +static DEFINE_MUTEX(nf_ct_helper_mutex); +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; +module_param_named(nf_conntrack_helper, nf_ct_auto_assign_helper, bool, 0644); +MODULE_PARM_DESC(nf_conntrack_helper, + "Enable automatic conntrack helper assignment (default 1)"); + +#ifdef CONFIG_SYSCTL +static struct ctl_table helper_sysctl_table[] = { + { + .procname = "nf_conntrack_helper", + .data = &init_net.ct.sysctl_auto_assign_helper, + .maxlen = sizeof(unsigned int), + .mode = 0644, + .proc_handler = proc_dointvec, + }, + {} +}; + +static int nf_conntrack_helper_init_sysctl(struct net *net) +{ + struct ctl_table *table; + + table = kmemdup(helper_sysctl_table, sizeof(helper_sysctl_table), + GFP_KERNEL); + if (!table) + goto out; + + table[0].data = &net->ct.sysctl_auto_assign_helper; + + /* Don't export sysctls to unprivileged users */ + if (net->user_ns != &init_user_ns) + table[0].procname = NULL; + + net->ct.helper_sysctl_header = + register_net_sysctl(net, "net/netfilter", table); + + if (!net->ct.helper_sysctl_header) { + pr_err("nf_conntrack_helper: can't register to sysctl.\n"); + goto out_register; + } + return 0; + +out_register: + kfree(table); +out: + return -ENOMEM; +} + +static void nf_conntrack_helper_fini_sysctl(struct net *net) +{ + struct ctl_table *table; + + table = net->ct.helper_sysctl_header->ctl_table_arg; + unregister_net_sysctl_table(net->ct.helper_sysctl_header); + kfree(table); +} +#else +static int nf_conntrack_helper_init_sysctl(struct net *net) +{ + return 0; +} + +static void nf_conntrack_helper_fini_sysctl(struct net *net) +{ +} +#endif /* CONFIG_SYSCTL */ + +/* Stupid hash, but collision free for the default registrations of the + * helpers currently in the kernel. */ +static unsigned int helper_hash(const struct nf_conntrack_tuple *tuple) +{ + return (((tuple->src.l3num << 8) | tuple->dst.protonum) ^ + (__force __u16)tuple->src.u.all) % nf_ct_helper_hsize; +} + +static struct nf_conntrack_helper * +__nf_ct_helper_find(const struct nf_conntrack_tuple *tuple) +{ + struct nf_conntrack_helper *helper; + struct nf_conntrack_tuple_mask mask = { .src.u.all = htons(0xFFFF) }; + unsigned int h; + + if (!nf_ct_helper_count) + return NULL; + + h = helper_hash(tuple); + hlist_for_each_entry_rcu(helper, &nf_ct_helper_hash[h], hnode) { + if (nf_ct_tuple_src_mask_cmp(tuple, &helper->tuple, &mask)) + return helper; + } + return NULL; +} + +struct nf_conntrack_helper * +__nf_conntrack_helper_find(const char *name, u16 l3num, u8 protonum) +{ + struct nf_conntrack_helper *h; + unsigned int i; + + for (i = 0; i < nf_ct_helper_hsize; i++) { + hlist_for_each_entry_rcu(h, &nf_ct_helper_hash[i], hnode) { + if (!strcmp(h->name, name) && + h->tuple.src.l3num == l3num && + h->tuple.dst.protonum == protonum) + return h; + } + } + return NULL; +} +EXPORT_SYMBOL_GPL(__nf_conntrack_helper_find); + +struct nf_conntrack_helper * +nf_conntrack_helper_try_module_get(const char *name, u16 l3num, u8 protonum) +{ + struct nf_conntrack_helper *h; + + h = __nf_conntrack_helper_find(name, l3num, protonum); +#ifdef CONFIG_MODULES + if (h == NULL) { + if (request_module("nfct-helper-%s", name) == 0) + h = __nf_conntrack_helper_find(name, l3num, protonum); + } +#endif + if (h != NULL && !try_module_get(h->me)) + h = NULL; + + return h; +} +EXPORT_SYMBOL_GPL(nf_conntrack_helper_try_module_get); + +struct nf_conn_help * +nf_ct_helper_ext_add(struct nf_conn *ct, + struct nf_conntrack_helper *helper, gfp_t gfp) +{ + struct nf_conn_help *help; + + help = nf_ct_ext_add_length(ct, NF_CT_EXT_HELPER, + helper->data_len, gfp); + if (help) + INIT_HLIST_HEAD(&help->expectations); + else + pr_debug("failed to add helper extension area"); + return help; +} +EXPORT_SYMBOL_GPL(nf_ct_helper_ext_add); + +int __nf_ct_try_assign_helper(struct nf_conn *ct, struct nf_conn *tmpl, + gfp_t flags) +{ + struct nf_conntrack_helper *helper = NULL; + struct nf_conn_help *help; + struct net *net = nf_ct_net(ct); + int ret = 0; + + /* We already got a helper explicitly attached. The function + * nf_conntrack_alter_reply - in case NAT is in use - asks for looking + * the helper up again. Since now the user is in full control of + * making consistent helper configurations, skip this automatic + * re-lookup, otherwise we'll lose the helper. + */ + if (test_bit(IPS_HELPER_BIT, &ct->status)) + return 0; + + if (tmpl != NULL) { + help = nfct_help(tmpl); + if (help != NULL) { + helper = help->helper; + set_bit(IPS_HELPER_BIT, &ct->status); + } + } + + help = nfct_help(ct); + if (net->ct.sysctl_auto_assign_helper && helper == NULL) { + helper = __nf_ct_helper_find(&ct->tuplehash[IP_CT_DIR_REPLY].tuple); + if (unlikely(!net->ct.auto_assign_helper_warned && helper)) { + pr_info("nf_conntrack: automatic helper " + "assignment is deprecated and it will " + "be removed soon. Use the iptables CT target " + "to attach helpers instead.\n"); + net->ct.auto_assign_helper_warned = true; + } + } + + if (helper == NULL) { + if (help) + RCU_INIT_POINTER(help->helper, NULL); + goto out; + } + + if (help == NULL) { + help = nf_ct_helper_ext_add(ct, helper, flags); + if (help == NULL) { + ret = -ENOMEM; + goto out; + } + } else { + /* We only allow helper re-assignment of the same sort since + * we cannot reallocate the helper extension area. + */ + struct nf_conntrack_helper *tmp = rcu_dereference(help->helper); + + if (tmp && tmp->help != helper->help) { + RCU_INIT_POINTER(help->helper, NULL); + goto out; + } + } + + rcu_assign_pointer(help->helper, helper); +out: + return ret; +} +EXPORT_SYMBOL_GPL(__nf_ct_try_assign_helper); + +/* appropriate ct lock protecting must be taken by caller */ +static inline int unhelp(struct nf_conntrack_tuple_hash *i, + const struct nf_conntrack_helper *me) +{ + struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(i); + struct nf_conn_help *help = nfct_help(ct); + + if (help && rcu_dereference_raw(help->helper) == me) { + nf_conntrack_event(IPCT_HELPER, ct); + RCU_INIT_POINTER(help->helper, NULL); + } + return 0; +} + +void nf_ct_helper_destroy(struct nf_conn *ct) +{ + struct nf_conn_help *help = nfct_help(ct); + struct nf_conntrack_helper *helper; + + if (help) { + rcu_read_lock(); + helper = rcu_dereference(help->helper); + if (helper && helper->destroy) + helper->destroy(ct); + rcu_read_unlock(); + } +} + +static LIST_HEAD(nf_ct_helper_expectfn_list); + +void nf_ct_helper_expectfn_register(struct nf_ct_helper_expectfn *n) +{ + spin_lock_bh(&nf_conntrack_expect_lock); + list_add_rcu(&n->head, &nf_ct_helper_expectfn_list); + spin_unlock_bh(&nf_conntrack_expect_lock); +} +EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_register); + +void nf_ct_helper_expectfn_unregister(struct nf_ct_helper_expectfn *n) +{ + spin_lock_bh(&nf_conntrack_expect_lock); + list_del_rcu(&n->head); + spin_unlock_bh(&nf_conntrack_expect_lock); +} +EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_unregister); + +struct nf_ct_helper_expectfn * +nf_ct_helper_expectfn_find_by_name(const char *name) +{ + struct nf_ct_helper_expectfn *cur; + bool found = false; + + rcu_read_lock(); + list_for_each_entry_rcu(cur, &nf_ct_helper_expectfn_list, head) { + if (!strcmp(cur->name, name)) { + found = true; + break; + } + } + rcu_read_unlock(); + return found ? cur : NULL; +} +EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_name); + +struct nf_ct_helper_expectfn * +nf_ct_helper_expectfn_find_by_symbol(const void *symbol) +{ + struct nf_ct_helper_expectfn *cur; + bool found = false; + + rcu_read_lock(); + list_for_each_entry_rcu(cur, &nf_ct_helper_expectfn_list, head) { + if (cur->expectfn == symbol) { + found = true; + break; + } + } + rcu_read_unlock(); + return found ? cur : NULL; +} +EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_symbol); + +__printf(3, 4) +void nf_ct_helper_log(struct sk_buff *skb, const struct nf_conn *ct, + const char *fmt, ...) +{ + const struct nf_conn_help *help; + const struct nf_conntrack_helper *helper; + struct va_format vaf; + va_list args; + + va_start(args, fmt); + + vaf.fmt = fmt; + vaf.va = &args; + + /* Called from the helper function, this call never fails */ + help = nfct_help(ct); + + /* rcu_read_lock()ed by nf_hook_slow */ + helper = rcu_dereference(help->helper); + + nf_log_packet(nf_ct_net(ct), nf_ct_l3num(ct), 0, skb, NULL, NULL, NULL, + "nf_ct_%s: dropping packet: %pV ", helper->name, &vaf); + + va_end(args); +} +EXPORT_SYMBOL_GPL(nf_ct_helper_log); + +int nf_conntrack_helper_register(struct nf_conntrack_helper *me) +{ + int ret = 0; + struct nf_conntrack_helper *cur; + unsigned int h = helper_hash(&me->tuple); + + BUG_ON(me->expect_policy == NULL); + BUG_ON(me->expect_class_max >= NF_CT_MAX_EXPECT_CLASSES); + BUG_ON(strlen(me->name) > NF_CT_HELPER_NAME_LEN - 1); + + mutex_lock(&nf_ct_helper_mutex); + hlist_for_each_entry(cur, &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 ret; +} +EXPORT_SYMBOL_GPL(nf_conntrack_helper_register); + +static void __nf_conntrack_helper_unregister(struct nf_conntrack_helper *me, + struct net *net) +{ + struct nf_conntrack_tuple_hash *h; + struct nf_conntrack_expect *exp; + const struct hlist_node *next; + const struct hlist_nulls_node *nn; + unsigned int i; + int cpu; + + /* Get rid of expectations */ + spin_lock_bh(&nf_conntrack_expect_lock); + for (i = 0; i < nf_ct_expect_hsize; i++) { + hlist_for_each_entry_safe(exp, next, + &net->ct.expect_hash[i], hnode) { + struct nf_conn_help *help = nfct_help(exp->master); + if ((rcu_dereference_protected( + help->helper, + lockdep_is_held(&nf_conntrack_expect_lock) + ) == me || exp->helper == me) && + del_timer(&exp->timeout)) { + nf_ct_unlink_expect(exp); + nf_ct_expect_put(exp); + } + } + } + spin_unlock_bh(&nf_conntrack_expect_lock); + + /* Get rid of expecteds, set helpers to NULL. */ + for_each_possible_cpu(cpu) { + struct ct_pcpu *pcpu = per_cpu_ptr(net->ct.pcpu_lists, cpu); + + spin_lock_bh(&pcpu->lock); + hlist_nulls_for_each_entry(h, nn, &pcpu->unconfirmed, hnnode) + unhelp(h, me); + spin_unlock_bh(&pcpu->lock); + } + local_bh_disable(); + for (i = 0; i < net->ct.htable_size; i++) { + spin_lock(&nf_conntrack_locks[i % CONNTRACK_LOCKS]); + if (i < net->ct.htable_size) { + hlist_nulls_for_each_entry(h, nn, &net->ct.hash[i], hnnode) + unhelp(h, me); + } + spin_unlock(&nf_conntrack_locks[i % CONNTRACK_LOCKS]); + } + local_bh_enable(); +} + +void nf_conntrack_helper_unregister(struct nf_conntrack_helper *me) +{ + struct net *net; + + mutex_lock(&nf_ct_helper_mutex); + hlist_del_rcu(&me->hnode); + nf_ct_helper_count--; + mutex_unlock(&nf_ct_helper_mutex); + + /* Make sure every nothing is still using the helper unless its a + * connection in the hash. + */ + synchronize_rcu(); + + rtnl_lock(); + for_each_net(net) + __nf_conntrack_helper_unregister(me, net); + rtnl_unlock(); +} +EXPORT_SYMBOL_GPL(nf_conntrack_helper_unregister); + +static struct nf_ct_ext_type helper_extend __read_mostly = { + .len = sizeof(struct nf_conn_help), + .align = __alignof__(struct nf_conn_help), + .id = NF_CT_EXT_HELPER, +}; + +int nf_conntrack_helper_pernet_init(struct net *net) +{ + net->ct.auto_assign_helper_warned = false; + net->ct.sysctl_auto_assign_helper = nf_ct_auto_assign_helper; + return nf_conntrack_helper_init_sysctl(net); +} + +void nf_conntrack_helper_pernet_fini(struct net *net) +{ + nf_conntrack_helper_fini_sysctl(net); +} + +int nf_conntrack_helper_init(void) +{ + int ret; + nf_ct_helper_hsize = 1; /* gets rounded up to use one page */ + nf_ct_helper_hash = + nf_ct_alloc_hashtable(&nf_ct_helper_hsize, 0); + if (!nf_ct_helper_hash) + return -ENOMEM; + + ret = nf_ct_extend_register(&helper_extend); + if (ret < 0) { + pr_err("nf_ct_helper: Unable to register helper extension.\n"); + goto out_extend; + } + + return 0; +out_extend: + nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_hsize); + return ret; +} + +void nf_conntrack_helper_fini(void) +{ + nf_ct_extend_unregister(&helper_extend); + nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_hsize); +} -- cgit v1.2.3-54-g00ecf