diff options
Diffstat (limited to 'net/netfilter/nf_conntrack_expect.c')
-rw-r--r-- | net/netfilter/nf_conntrack_expect.c | 659 |
1 files changed, 659 insertions, 0 deletions
diff --git a/net/netfilter/nf_conntrack_expect.c b/net/netfilter/nf_conntrack_expect.c new file mode 100644 index 000000000..7a17070c5 --- /dev/null +++ b/net/netfilter/nf_conntrack_expect.c @@ -0,0 +1,659 @@ +/* Expectation handling for nf_conntrack. */ + +/* (C) 1999-2001 Paul `Rusty' Russell + * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org> + * (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org> + * (c) 2005-2012 Patrick McHardy <kaber@trash.net> + * + * 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 <linux/types.h> +#include <linux/netfilter.h> +#include <linux/skbuff.h> +#include <linux/proc_fs.h> +#include <linux/seq_file.h> +#include <linux/stddef.h> +#include <linux/slab.h> +#include <linux/err.h> +#include <linux/percpu.h> +#include <linux/kernel.h> +#include <linux/jhash.h> +#include <linux/moduleparam.h> +#include <linux/export.h> +#include <net/net_namespace.h> + +#include <net/netfilter/nf_conntrack.h> +#include <net/netfilter/nf_conntrack_core.h> +#include <net/netfilter/nf_conntrack_expect.h> +#include <net/netfilter/nf_conntrack_helper.h> +#include <net/netfilter/nf_conntrack_tuple.h> +#include <net/netfilter/nf_conntrack_zones.h> + +unsigned int nf_ct_expect_hsize __read_mostly; +EXPORT_SYMBOL_GPL(nf_ct_expect_hsize); + +unsigned int nf_ct_expect_max __read_mostly; + +static struct kmem_cache *nf_ct_expect_cachep __read_mostly; + +/* nf_conntrack_expect helper functions */ +void nf_ct_unlink_expect_report(struct nf_conntrack_expect *exp, + u32 portid, int report) +{ + struct nf_conn_help *master_help = nfct_help(exp->master); + struct net *net = nf_ct_exp_net(exp); + + NF_CT_ASSERT(master_help); + NF_CT_ASSERT(!timer_pending(&exp->timeout)); + + hlist_del_rcu(&exp->hnode); + net->ct.expect_count--; + + hlist_del(&exp->lnode); + master_help->expecting[exp->class]--; + + nf_ct_expect_event_report(IPEXP_DESTROY, exp, portid, report); + nf_ct_expect_put(exp); + + NF_CT_STAT_INC(net, expect_delete); +} +EXPORT_SYMBOL_GPL(nf_ct_unlink_expect_report); + +static void nf_ct_expectation_timed_out(unsigned long ul_expect) +{ + struct nf_conntrack_expect *exp = (void *)ul_expect; + + spin_lock_bh(&nf_conntrack_expect_lock); + nf_ct_unlink_expect(exp); + spin_unlock_bh(&nf_conntrack_expect_lock); + nf_ct_expect_put(exp); +} + +static unsigned int nf_ct_expect_dst_hash(const struct nf_conntrack_tuple *tuple) +{ + unsigned int hash; + + if (unlikely(!nf_conntrack_hash_rnd)) { + init_nf_conntrack_hash_rnd(); + } + + hash = jhash2(tuple->dst.u3.all, ARRAY_SIZE(tuple->dst.u3.all), + (((tuple->dst.protonum ^ tuple->src.l3num) << 16) | + (__force __u16)tuple->dst.u.all) ^ nf_conntrack_hash_rnd); + + return reciprocal_scale(hash, nf_ct_expect_hsize); +} + +struct nf_conntrack_expect * +__nf_ct_expect_find(struct net *net, u16 zone, + const struct nf_conntrack_tuple *tuple) +{ + struct nf_conntrack_expect *i; + unsigned int h; + + if (!net->ct.expect_count) + return NULL; + + h = nf_ct_expect_dst_hash(tuple); + hlist_for_each_entry_rcu(i, &net->ct.expect_hash[h], hnode) { + if (nf_ct_tuple_mask_cmp(tuple, &i->tuple, &i->mask) && + nf_ct_zone(i->master) == zone) + return i; + } + return NULL; +} +EXPORT_SYMBOL_GPL(__nf_ct_expect_find); + +/* Just find a expectation corresponding to a tuple. */ +struct nf_conntrack_expect * +nf_ct_expect_find_get(struct net *net, u16 zone, + const struct nf_conntrack_tuple *tuple) +{ + struct nf_conntrack_expect *i; + + rcu_read_lock(); + i = __nf_ct_expect_find(net, zone, tuple); + if (i && !atomic_inc_not_zero(&i->use)) + i = NULL; + rcu_read_unlock(); + + return i; +} +EXPORT_SYMBOL_GPL(nf_ct_expect_find_get); + +/* If an expectation for this connection is found, it gets delete from + * global list then returned. */ +struct nf_conntrack_expect * +nf_ct_find_expectation(struct net *net, u16 zone, + const struct nf_conntrack_tuple *tuple) +{ + struct nf_conntrack_expect *i, *exp = NULL; + unsigned int h; + + if (!net->ct.expect_count) + return NULL; + + h = nf_ct_expect_dst_hash(tuple); + hlist_for_each_entry(i, &net->ct.expect_hash[h], hnode) { + if (!(i->flags & NF_CT_EXPECT_INACTIVE) && + nf_ct_tuple_mask_cmp(tuple, &i->tuple, &i->mask) && + nf_ct_zone(i->master) == zone) { + exp = i; + break; + } + } + if (!exp) + return NULL; + + /* If master is not in hash table yet (ie. packet hasn't left + this machine yet), how can other end know about expected? + Hence these are not the droids you are looking for (if + master ct never got confirmed, we'd hold a reference to it + and weird things would happen to future packets). */ + if (!nf_ct_is_confirmed(exp->master)) + return NULL; + + /* Avoid race with other CPUs, that for exp->master ct, is + * about to invoke ->destroy(), or nf_ct_delete() via timeout + * or early_drop(). + * + * The atomic_inc_not_zero() check tells: If that fails, we + * know that the ct is being destroyed. If it succeeds, we + * can be sure the ct cannot disappear underneath. + */ + if (unlikely(nf_ct_is_dying(exp->master) || + !atomic_inc_not_zero(&exp->master->ct_general.use))) + return NULL; + + if (exp->flags & NF_CT_EXPECT_PERMANENT) { + atomic_inc(&exp->use); + return exp; + } else if (del_timer(&exp->timeout)) { + nf_ct_unlink_expect(exp); + return exp; + } + /* Undo exp->master refcnt increase, if del_timer() failed */ + nf_ct_put(exp->master); + + return NULL; +} + +/* delete all expectations for this conntrack */ +void nf_ct_remove_expectations(struct nf_conn *ct) +{ + struct nf_conn_help *help = nfct_help(ct); + struct nf_conntrack_expect *exp; + struct hlist_node *next; + + /* Optimization: most connection never expect any others. */ + if (!help) + return; + + spin_lock_bh(&nf_conntrack_expect_lock); + hlist_for_each_entry_safe(exp, next, &help->expectations, lnode) { + if (del_timer(&exp->timeout)) { + nf_ct_unlink_expect(exp); + nf_ct_expect_put(exp); + } + } + spin_unlock_bh(&nf_conntrack_expect_lock); +} +EXPORT_SYMBOL_GPL(nf_ct_remove_expectations); + +/* Would two expected things clash? */ +static inline int expect_clash(const struct nf_conntrack_expect *a, + const struct nf_conntrack_expect *b) +{ + /* Part covered by intersection of masks must be unequal, + otherwise they clash */ + struct nf_conntrack_tuple_mask intersect_mask; + int count; + + intersect_mask.src.u.all = a->mask.src.u.all & b->mask.src.u.all; + + for (count = 0; count < NF_CT_TUPLE_L3SIZE; count++){ + intersect_mask.src.u3.all[count] = + a->mask.src.u3.all[count] & b->mask.src.u3.all[count]; + } + + return nf_ct_tuple_mask_cmp(&a->tuple, &b->tuple, &intersect_mask); +} + +static inline int expect_matches(const struct nf_conntrack_expect *a, + const struct nf_conntrack_expect *b) +{ + return a->master == b->master && a->class == b->class && + nf_ct_tuple_equal(&a->tuple, &b->tuple) && + nf_ct_tuple_mask_equal(&a->mask, &b->mask) && + nf_ct_zone(a->master) == nf_ct_zone(b->master); +} + +/* Generally a bad idea to call this: could have matched already. */ +void nf_ct_unexpect_related(struct nf_conntrack_expect *exp) +{ + spin_lock_bh(&nf_conntrack_expect_lock); + if (del_timer(&exp->timeout)) { + nf_ct_unlink_expect(exp); + nf_ct_expect_put(exp); + } + spin_unlock_bh(&nf_conntrack_expect_lock); +} +EXPORT_SYMBOL_GPL(nf_ct_unexpect_related); + +/* We don't increase the master conntrack refcount for non-fulfilled + * conntracks. During the conntrack destruction, the expectations are + * always killed before the conntrack itself */ +struct nf_conntrack_expect *nf_ct_expect_alloc(struct nf_conn *me) +{ + struct nf_conntrack_expect *new; + + new = kmem_cache_alloc(nf_ct_expect_cachep, GFP_ATOMIC); + if (!new) + return NULL; + + new->master = me; + atomic_set(&new->use, 1); + return new; +} +EXPORT_SYMBOL_GPL(nf_ct_expect_alloc); + +void nf_ct_expect_init(struct nf_conntrack_expect *exp, unsigned int class, + u_int8_t family, + const union nf_inet_addr *saddr, + const union nf_inet_addr *daddr, + u_int8_t proto, const __be16 *src, const __be16 *dst) +{ + int len; + + if (family == AF_INET) + len = 4; + else + len = 16; + + exp->flags = 0; + exp->class = class; + exp->expectfn = NULL; + exp->helper = NULL; + exp->tuple.src.l3num = family; + exp->tuple.dst.protonum = proto; + + if (saddr) { + memcpy(&exp->tuple.src.u3, saddr, len); + if (sizeof(exp->tuple.src.u3) > len) + /* address needs to be cleared for nf_ct_tuple_equal */ + memset((void *)&exp->tuple.src.u3 + len, 0x00, + sizeof(exp->tuple.src.u3) - len); + memset(&exp->mask.src.u3, 0xFF, len); + if (sizeof(exp->mask.src.u3) > len) + memset((void *)&exp->mask.src.u3 + len, 0x00, + sizeof(exp->mask.src.u3) - len); + } else { + memset(&exp->tuple.src.u3, 0x00, sizeof(exp->tuple.src.u3)); + memset(&exp->mask.src.u3, 0x00, sizeof(exp->mask.src.u3)); + } + + if (src) { + exp->tuple.src.u.all = *src; + exp->mask.src.u.all = htons(0xFFFF); + } else { + exp->tuple.src.u.all = 0; + exp->mask.src.u.all = 0; + } + + memcpy(&exp->tuple.dst.u3, daddr, len); + if (sizeof(exp->tuple.dst.u3) > len) + /* address needs to be cleared for nf_ct_tuple_equal */ + memset((void *)&exp->tuple.dst.u3 + len, 0x00, + sizeof(exp->tuple.dst.u3) - len); + + exp->tuple.dst.u.all = *dst; + +#ifdef CONFIG_NF_NAT_NEEDED + memset(&exp->saved_addr, 0, sizeof(exp->saved_addr)); + memset(&exp->saved_proto, 0, sizeof(exp->saved_proto)); +#endif +} +EXPORT_SYMBOL_GPL(nf_ct_expect_init); + +static void nf_ct_expect_free_rcu(struct rcu_head *head) +{ + struct nf_conntrack_expect *exp; + + exp = container_of(head, struct nf_conntrack_expect, rcu); + kmem_cache_free(nf_ct_expect_cachep, exp); +} + +void nf_ct_expect_put(struct nf_conntrack_expect *exp) +{ + if (atomic_dec_and_test(&exp->use)) + call_rcu(&exp->rcu, nf_ct_expect_free_rcu); +} +EXPORT_SYMBOL_GPL(nf_ct_expect_put); + +static int nf_ct_expect_insert(struct nf_conntrack_expect *exp) +{ + struct nf_conn_help *master_help = nfct_help(exp->master); + struct nf_conntrack_helper *helper; + struct net *net = nf_ct_exp_net(exp); + unsigned int h = nf_ct_expect_dst_hash(&exp->tuple); + + /* two references : one for hash insert, one for the timer */ + atomic_add(2, &exp->use); + + hlist_add_head(&exp->lnode, &master_help->expectations); + master_help->expecting[exp->class]++; + + hlist_add_head_rcu(&exp->hnode, &net->ct.expect_hash[h]); + net->ct.expect_count++; + + setup_timer(&exp->timeout, nf_ct_expectation_timed_out, + (unsigned long)exp); + helper = rcu_dereference_protected(master_help->helper, + lockdep_is_held(&nf_conntrack_expect_lock)); + if (helper) { + exp->timeout.expires = jiffies + + helper->expect_policy[exp->class].timeout * HZ; + } + add_timer(&exp->timeout); + + NF_CT_STAT_INC(net, expect_create); + return 0; +} + +/* Race with expectations being used means we could have none to find; OK. */ +static void evict_oldest_expect(struct nf_conn *master, + struct nf_conntrack_expect *new) +{ + struct nf_conn_help *master_help = nfct_help(master); + struct nf_conntrack_expect *exp, *last = NULL; + + hlist_for_each_entry(exp, &master_help->expectations, lnode) { + if (exp->class == new->class) + last = exp; + } + + if (last && del_timer(&last->timeout)) { + nf_ct_unlink_expect(last); + nf_ct_expect_put(last); + } +} + +static inline int __nf_ct_expect_check(struct nf_conntrack_expect *expect) +{ + const struct nf_conntrack_expect_policy *p; + struct nf_conntrack_expect *i; + struct nf_conn *master = expect->master; + struct nf_conn_help *master_help = nfct_help(master); + struct nf_conntrack_helper *helper; + struct net *net = nf_ct_exp_net(expect); + struct hlist_node *next; + unsigned int h; + int ret = 1; + + if (!master_help) { + ret = -ESHUTDOWN; + goto out; + } + h = nf_ct_expect_dst_hash(&expect->tuple); + hlist_for_each_entry_safe(i, next, &net->ct.expect_hash[h], hnode) { + if (expect_matches(i, expect)) { + if (del_timer(&i->timeout)) { + nf_ct_unlink_expect(i); + nf_ct_expect_put(i); + break; + } + } else if (expect_clash(i, expect)) { + ret = -EBUSY; + goto out; + } + } + /* Will be over limit? */ + helper = rcu_dereference_protected(master_help->helper, + lockdep_is_held(&nf_conntrack_expect_lock)); + if (helper) { + p = &helper->expect_policy[expect->class]; + if (p->max_expected && + master_help->expecting[expect->class] >= p->max_expected) { + evict_oldest_expect(master, expect); + if (master_help->expecting[expect->class] + >= p->max_expected) { + ret = -EMFILE; + goto out; + } + } + } + + if (net->ct.expect_count >= nf_ct_expect_max) { + net_warn_ratelimited("nf_conntrack: expectation table full\n"); + ret = -EMFILE; + } +out: + return ret; +} + +int nf_ct_expect_related_report(struct nf_conntrack_expect *expect, + u32 portid, int report) +{ + int ret; + + spin_lock_bh(&nf_conntrack_expect_lock); + ret = __nf_ct_expect_check(expect); + if (ret <= 0) + goto out; + + ret = nf_ct_expect_insert(expect); + if (ret < 0) + goto out; + spin_unlock_bh(&nf_conntrack_expect_lock); + nf_ct_expect_event_report(IPEXP_NEW, expect, portid, report); + return ret; +out: + spin_unlock_bh(&nf_conntrack_expect_lock); + return ret; +} +EXPORT_SYMBOL_GPL(nf_ct_expect_related_report); + +#ifdef CONFIG_NF_CONNTRACK_PROCFS +struct ct_expect_iter_state { + struct seq_net_private p; + unsigned int bucket; +}; + +static struct hlist_node *ct_expect_get_first(struct seq_file *seq) +{ + struct net *net = seq_file_net(seq); + struct ct_expect_iter_state *st = seq->private; + struct hlist_node *n; + + for (st->bucket = 0; st->bucket < nf_ct_expect_hsize; st->bucket++) { + n = rcu_dereference(hlist_first_rcu(&net->ct.expect_hash[st->bucket])); + if (n) + return n; + } + return NULL; +} + +static struct hlist_node *ct_expect_get_next(struct seq_file *seq, + struct hlist_node *head) +{ + struct net *net = seq_file_net(seq); + struct ct_expect_iter_state *st = seq->private; + + head = rcu_dereference(hlist_next_rcu(head)); + while (head == NULL) { + if (++st->bucket >= nf_ct_expect_hsize) + return NULL; + head = rcu_dereference(hlist_first_rcu(&net->ct.expect_hash[st->bucket])); + } + return head; +} + +static struct hlist_node *ct_expect_get_idx(struct seq_file *seq, loff_t pos) +{ + struct hlist_node *head = ct_expect_get_first(seq); + + if (head) + while (pos && (head = ct_expect_get_next(seq, head))) + pos--; + return pos ? NULL : head; +} + +static void *exp_seq_start(struct seq_file *seq, loff_t *pos) + __acquires(RCU) +{ + rcu_read_lock(); + return ct_expect_get_idx(seq, *pos); +} + +static void *exp_seq_next(struct seq_file *seq, void *v, loff_t *pos) +{ + (*pos)++; + return ct_expect_get_next(seq, v); +} + +static void exp_seq_stop(struct seq_file *seq, void *v) + __releases(RCU) +{ + rcu_read_unlock(); +} + +static int exp_seq_show(struct seq_file *s, void *v) +{ + struct nf_conntrack_expect *expect; + struct nf_conntrack_helper *helper; + struct hlist_node *n = v; + char *delim = ""; + + expect = hlist_entry(n, struct nf_conntrack_expect, hnode); + + if (expect->timeout.function) + seq_printf(s, "%ld ", timer_pending(&expect->timeout) + ? (long)(expect->timeout.expires - jiffies)/HZ : 0); + else + seq_printf(s, "- "); + seq_printf(s, "l3proto = %u proto=%u ", + expect->tuple.src.l3num, + expect->tuple.dst.protonum); + print_tuple(s, &expect->tuple, + __nf_ct_l3proto_find(expect->tuple.src.l3num), + __nf_ct_l4proto_find(expect->tuple.src.l3num, + expect->tuple.dst.protonum)); + + if (expect->flags & NF_CT_EXPECT_PERMANENT) { + seq_printf(s, "PERMANENT"); + delim = ","; + } + if (expect->flags & NF_CT_EXPECT_INACTIVE) { + seq_printf(s, "%sINACTIVE", delim); + delim = ","; + } + if (expect->flags & NF_CT_EXPECT_USERSPACE) + seq_printf(s, "%sUSERSPACE", delim); + + helper = rcu_dereference(nfct_help(expect->master)->helper); + if (helper) { + seq_printf(s, "%s%s", expect->flags ? " " : "", helper->name); + if (helper->expect_policy[expect->class].name) + seq_printf(s, "/%s", + helper->expect_policy[expect->class].name); + } + + seq_putc(s, '\n'); + + return 0; +} + +static const struct seq_operations exp_seq_ops = { + .start = exp_seq_start, + .next = exp_seq_next, + .stop = exp_seq_stop, + .show = exp_seq_show +}; + +static int exp_open(struct inode *inode, struct file *file) +{ + return seq_open_net(inode, file, &exp_seq_ops, + sizeof(struct ct_expect_iter_state)); +} + +static const struct file_operations exp_file_ops = { + .owner = THIS_MODULE, + .open = exp_open, + .read = seq_read, + .llseek = seq_lseek, + .release = seq_release_net, +}; +#endif /* CONFIG_NF_CONNTRACK_PROCFS */ + +static int exp_proc_init(struct net *net) +{ +#ifdef CONFIG_NF_CONNTRACK_PROCFS + struct proc_dir_entry *proc; + + proc = proc_create("nf_conntrack_expect", 0440, net->proc_net, + &exp_file_ops); + if (!proc) + return -ENOMEM; +#endif /* CONFIG_NF_CONNTRACK_PROCFS */ + return 0; +} + +static void exp_proc_remove(struct net *net) +{ +#ifdef CONFIG_NF_CONNTRACK_PROCFS + remove_proc_entry("nf_conntrack_expect", net->proc_net); +#endif /* CONFIG_NF_CONNTRACK_PROCFS */ +} + +module_param_named(expect_hashsize, nf_ct_expect_hsize, uint, 0400); + +int nf_conntrack_expect_pernet_init(struct net *net) +{ + int err = -ENOMEM; + + net->ct.expect_count = 0; + net->ct.expect_hash = nf_ct_alloc_hashtable(&nf_ct_expect_hsize, 0); + if (net->ct.expect_hash == NULL) + goto err1; + + err = exp_proc_init(net); + if (err < 0) + goto err2; + + return 0; +err2: + nf_ct_free_hashtable(net->ct.expect_hash, nf_ct_expect_hsize); +err1: + return err; +} + +void nf_conntrack_expect_pernet_fini(struct net *net) +{ + exp_proc_remove(net); + nf_ct_free_hashtable(net->ct.expect_hash, nf_ct_expect_hsize); +} + +int nf_conntrack_expect_init(void) +{ + if (!nf_ct_expect_hsize) { + nf_ct_expect_hsize = nf_conntrack_htable_size / 256; + if (!nf_ct_expect_hsize) + nf_ct_expect_hsize = 1; + } + nf_ct_expect_max = nf_ct_expect_hsize * 4; + nf_ct_expect_cachep = kmem_cache_create("nf_conntrack_expect", + sizeof(struct nf_conntrack_expect), + 0, 0, NULL); + if (!nf_ct_expect_cachep) + return -ENOMEM; + return 0; +} + +void nf_conntrack_expect_fini(void) +{ + rcu_barrier(); /* Wait for call_rcu() before destroy */ + kmem_cache_destroy(nf_ct_expect_cachep); +} |