diff options
Diffstat (limited to 'net/netfilter/nf_conntrack_expect.c')
-rw-r--r-- | net/netfilter/nf_conntrack_expect.c | 442 |
1 files changed, 442 insertions, 0 deletions
diff --git a/net/netfilter/nf_conntrack_expect.c b/net/netfilter/nf_conntrack_expect.c new file mode 100644 index 0000000..588d379 --- /dev/null +++ b/net/netfilter/nf_conntrack_expect.c @@ -0,0 +1,442 @@ +/* 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> + * + * 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 <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> + +LIST_HEAD(nf_conntrack_expect_list); +EXPORT_SYMBOL_GPL(nf_conntrack_expect_list); + +kmem_cache_t *nf_conntrack_expect_cachep __read_mostly; +static unsigned int nf_conntrack_expect_next_id; + +/* nf_conntrack_expect helper functions */ +void nf_ct_unlink_expect(struct nf_conntrack_expect *exp) +{ + struct nf_conn_help *master_help = nfct_help(exp->master); + + NF_CT_ASSERT(master_help); + NF_CT_ASSERT(!timer_pending(&exp->timeout)); + + list_del(&exp->list); + NF_CT_STAT_INC(expect_delete); + master_help->expecting--; + nf_conntrack_expect_put(exp); +} +EXPORT_SYMBOL_GPL(nf_ct_unlink_expect); + +static void expectation_timed_out(unsigned long ul_expect) +{ + struct nf_conntrack_expect *exp = (void *)ul_expect; + + write_lock_bh(&nf_conntrack_lock); + nf_ct_unlink_expect(exp); + write_unlock_bh(&nf_conntrack_lock); + nf_conntrack_expect_put(exp); +} + +struct nf_conntrack_expect * +__nf_conntrack_expect_find(const struct nf_conntrack_tuple *tuple) +{ + struct nf_conntrack_expect *i; + + list_for_each_entry(i, &nf_conntrack_expect_list, list) { + if (nf_ct_tuple_mask_cmp(tuple, &i->tuple, &i->mask)) + return i; + } + return NULL; +} +EXPORT_SYMBOL_GPL(__nf_conntrack_expect_find); + +/* Just find a expectation corresponding to a tuple. */ +struct nf_conntrack_expect * +nf_conntrack_expect_find_get(const struct nf_conntrack_tuple *tuple) +{ + struct nf_conntrack_expect *i; + + read_lock_bh(&nf_conntrack_lock); + i = __nf_conntrack_expect_find(tuple); + if (i) + atomic_inc(&i->use); + read_unlock_bh(&nf_conntrack_lock); + + return i; +} +EXPORT_SYMBOL_GPL(nf_conntrack_expect_find_get); + +/* If an expectation for this connection is found, it gets delete from + * global list then returned. */ +struct nf_conntrack_expect * +find_expectation(const struct nf_conntrack_tuple *tuple) +{ + struct nf_conntrack_expect *i; + + list_for_each_entry(i, &nf_conntrack_expect_list, list) { + /* 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_tuple_mask_cmp(tuple, &i->tuple, &i->mask) + && nf_ct_is_confirmed(i->master)) { + if (i->flags & NF_CT_EXPECT_PERMANENT) { + atomic_inc(&i->use); + return i; + } else if (del_timer(&i->timeout)) { + nf_ct_unlink_expect(i); + return i; + } + } + } + return NULL; +} + +/* delete all expectations for this conntrack */ +void nf_ct_remove_expectations(struct nf_conn *ct) +{ + struct nf_conntrack_expect *i, *tmp; + struct nf_conn_help *help = nfct_help(ct); + + /* Optimization: most connection never expect any others. */ + if (!help || help->expecting == 0) + return; + + list_for_each_entry_safe(i, tmp, &nf_conntrack_expect_list, list) { + if (i->master == ct && del_timer(&i->timeout)) { + nf_ct_unlink_expect(i); + nf_conntrack_expect_put(i); + } + } +} +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 intersect_mask; + int count; + + intersect_mask.src.l3num = a->mask.src.l3num & b->mask.src.l3num; + intersect_mask.src.u.all = a->mask.src.u.all & b->mask.src.u.all; + intersect_mask.dst.u.all = a->mask.dst.u.all & b->mask.dst.u.all; + intersect_mask.dst.protonum = a->mask.dst.protonum + & b->mask.dst.protonum; + + 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]; + } + + for (count = 0; count < NF_CT_TUPLE_L3SIZE; count++){ + intersect_mask.dst.u3.all[count] = + a->mask.dst.u3.all[count] & b->mask.dst.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 + && nf_ct_tuple_equal(&a->tuple, &b->tuple) + && nf_ct_tuple_equal(&a->mask, &b->mask); +} + +/* Generally a bad idea to call this: could have matched already. */ +void nf_conntrack_unexpect_related(struct nf_conntrack_expect *exp) +{ + struct nf_conntrack_expect *i; + + write_lock_bh(&nf_conntrack_lock); + /* choose the the oldest expectation to evict */ + list_for_each_entry_reverse(i, &nf_conntrack_expect_list, list) { + if (expect_matches(i, exp) && del_timer(&i->timeout)) { + nf_ct_unlink_expect(i); + write_unlock_bh(&nf_conntrack_lock); + nf_conntrack_expect_put(i); + return; + } + } + write_unlock_bh(&nf_conntrack_lock); +} +EXPORT_SYMBOL_GPL(nf_conntrack_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_conntrack_expect_alloc(struct nf_conn *me) +{ + struct nf_conntrack_expect *new; + + new = kmem_cache_alloc(nf_conntrack_expect_cachep, GFP_ATOMIC); + if (!new) + return NULL; + + new->master = me; + atomic_set(&new->use, 1); + return new; +} +EXPORT_SYMBOL_GPL(nf_conntrack_expect_alloc); + +void nf_conntrack_expect_init(struct nf_conntrack_expect *exp, int family, + union nf_conntrack_address *saddr, + union nf_conntrack_address *daddr, + u_int8_t proto, __be16 *src, __be16 *dst) +{ + int len; + + if (family == AF_INET) + len = 4; + else + len = 16; + + exp->flags = 0; + exp->expectfn = NULL; + exp->helper = NULL; + exp->tuple.src.l3num = family; + exp->tuple.dst.protonum = proto; + exp->mask.src.l3num = 0xFFFF; + exp->mask.dst.protonum = 0xFF; + + 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 (daddr) { + 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); + memset(&exp->mask.dst.u3, 0xFF, len); + if (sizeof(exp->mask.dst.u3) > len) + memset((void *)&exp->mask.dst.u3 + len, 0x00, + sizeof(exp->mask.dst.u3) - len); + } else { + memset(&exp->tuple.dst.u3, 0x00, sizeof(exp->tuple.dst.u3)); + memset(&exp->mask.dst.u3, 0x00, sizeof(exp->mask.dst.u3)); + } + + if (src) { + exp->tuple.src.u.all = (__force u16)*src; + exp->mask.src.u.all = 0xFFFF; + } else { + exp->tuple.src.u.all = 0; + exp->mask.src.u.all = 0; + } + + if (dst) { + exp->tuple.dst.u.all = (__force u16)*dst; + exp->mask.dst.u.all = 0xFFFF; + } else { + exp->tuple.dst.u.all = 0; + exp->mask.dst.u.all = 0; + } +} +EXPORT_SYMBOL_GPL(nf_conntrack_expect_init); + +void nf_conntrack_expect_put(struct nf_conntrack_expect *exp) +{ + if (atomic_dec_and_test(&exp->use)) + kmem_cache_free(nf_conntrack_expect_cachep, exp); +} +EXPORT_SYMBOL_GPL(nf_conntrack_expect_put); + +static void nf_conntrack_expect_insert(struct nf_conntrack_expect *exp) +{ + struct nf_conn_help *master_help = nfct_help(exp->master); + + atomic_inc(&exp->use); + master_help->expecting++; + list_add(&exp->list, &nf_conntrack_expect_list); + + init_timer(&exp->timeout); + exp->timeout.data = (unsigned long)exp; + exp->timeout.function = expectation_timed_out; + exp->timeout.expires = jiffies + master_help->helper->timeout * HZ; + add_timer(&exp->timeout); + + exp->id = ++nf_conntrack_expect_next_id; + atomic_inc(&exp->use); + NF_CT_STAT_INC(expect_create); +} + +/* 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 *i; + + list_for_each_entry_reverse(i, &nf_conntrack_expect_list, list) { + if (i->master == master) { + if (del_timer(&i->timeout)) { + nf_ct_unlink_expect(i); + nf_conntrack_expect_put(i); + } + break; + } + } +} + +static inline int refresh_timer(struct nf_conntrack_expect *i) +{ + struct nf_conn_help *master_help = nfct_help(i->master); + + if (!del_timer(&i->timeout)) + return 0; + + i->timeout.expires = jiffies + master_help->helper->timeout*HZ; + add_timer(&i->timeout); + return 1; +} + +int nf_conntrack_expect_related(struct nf_conntrack_expect *expect) +{ + struct nf_conntrack_expect *i; + struct nf_conn *master = expect->master; + struct nf_conn_help *master_help = nfct_help(master); + int ret; + + NF_CT_ASSERT(master_help); + + write_lock_bh(&nf_conntrack_lock); + list_for_each_entry(i, &nf_conntrack_expect_list, list) { + if (expect_matches(i, expect)) { + /* Refresh timer: if it's dying, ignore.. */ + if (refresh_timer(i)) { + ret = 0; + goto out; + } + } else if (expect_clash(i, expect)) { + ret = -EBUSY; + goto out; + } + } + /* Will be over limit? */ + if (master_help->helper->max_expected && + master_help->expecting >= master_help->helper->max_expected) + evict_oldest_expect(master); + + nf_conntrack_expect_insert(expect); + nf_conntrack_expect_event(IPEXP_NEW, expect); + ret = 0; +out: + write_unlock_bh(&nf_conntrack_lock); + return ret; +} +EXPORT_SYMBOL_GPL(nf_conntrack_expect_related); + +#ifdef CONFIG_PROC_FS +static void *exp_seq_start(struct seq_file *s, loff_t *pos) +{ + struct list_head *e = &nf_conntrack_expect_list; + loff_t i; + + /* strange seq_file api calls stop even if we fail, + * thus we need to grab lock since stop unlocks */ + read_lock_bh(&nf_conntrack_lock); + + if (list_empty(e)) + return NULL; + + for (i = 0; i <= *pos; i++) { + e = e->next; + if (e == &nf_conntrack_expect_list) + return NULL; + } + return e; +} + +static void *exp_seq_next(struct seq_file *s, void *v, loff_t *pos) +{ + struct list_head *e = v; + + ++*pos; + e = e->next; + + if (e == &nf_conntrack_expect_list) + return NULL; + + return e; +} + +static void exp_seq_stop(struct seq_file *s, void *v) +{ + read_unlock_bh(&nf_conntrack_lock); +} + +static int exp_seq_show(struct seq_file *s, void *v) +{ + struct nf_conntrack_expect *expect = v; + + 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)); + return seq_putc(s, '\n'); +} + +static 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(file, &exp_seq_ops); +} + +struct file_operations exp_file_ops = { + .owner = THIS_MODULE, + .open = exp_open, + .read = seq_read, + .llseek = seq_lseek, + .release = seq_release +}; +#endif /* CONFIG_PROC_FS */ |