diff options
Diffstat (limited to 'net/netfilter/nf_conntrack_extend.c')
| -rw-r--r-- | net/netfilter/nf_conntrack_extend.c | 191 |
1 files changed, 191 insertions, 0 deletions
diff --git a/net/netfilter/nf_conntrack_extend.c b/net/netfilter/nf_conntrack_extend.c new file mode 100644 index 0000000..4b2c769 --- /dev/null +++ b/net/netfilter/nf_conntrack_extend.c @@ -0,0 +1,191 @@ +/* Structure dynamic extension infrastructure + * Copyright (C) 2004 Rusty Russell IBM Corporation + * Copyright (C) 2007 Netfilter Core Team <coreteam@netfilter.org> + * Copyright (C) 2007 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 + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/mutex.h> +#include <linux/rcupdate.h> +#include <linux/slab.h> +#include <linux/skbuff.h> +#include <net/netfilter/nf_conntrack_extend.h> + +static struct nf_ct_ext_type *nf_ct_ext_types[NF_CT_EXT_NUM]; +static DEFINE_MUTEX(nf_ct_ext_type_mutex); + +void __nf_ct_ext_destroy(struct nf_conn *ct) +{ + unsigned int i; + struct nf_ct_ext_type *t; + + for (i = 0; i < NF_CT_EXT_NUM; i++) { + if (!nf_ct_ext_exist(ct, i)) + continue; + + rcu_read_lock(); + t = rcu_dereference(nf_ct_ext_types[i]); + + /* Here the nf_ct_ext_type might have been unregisterd. + * I.e., it has responsible to cleanup private + * area in all conntracks when it is unregisterd. + */ + if (t && t->destroy) + t->destroy(ct); + rcu_read_unlock(); + } +} +EXPORT_SYMBOL(__nf_ct_ext_destroy); + +static void * +nf_ct_ext_create(struct nf_ct_ext **ext, enum nf_ct_ext_id id, gfp_t gfp) +{ + unsigned int off, len; + struct nf_ct_ext_type *t; + + rcu_read_lock(); + t = rcu_dereference(nf_ct_ext_types[id]); + BUG_ON(t == NULL); + off = ALIGN(sizeof(struct nf_ct_ext), t->align); + len = off + t->len; + rcu_read_unlock(); + + *ext = kzalloc(t->alloc_size, gfp); + if (!*ext) + return NULL; + + INIT_RCU_HEAD(&(*ext)->rcu); + (*ext)->offset[id] = off; + (*ext)->len = len; + + return (void *)(*ext) + off; +} + +static void __nf_ct_ext_free_rcu(struct rcu_head *head) +{ + struct nf_ct_ext *ext = container_of(head, struct nf_ct_ext, rcu); + kfree(ext); +} + +void *__nf_ct_ext_add(struct nf_conn *ct, enum nf_ct_ext_id id, gfp_t gfp) +{ + struct nf_ct_ext *new; + int i, newlen, newoff; + struct nf_ct_ext_type *t; + + /* Conntrack must not be confirmed to avoid races on reallocation. */ + NF_CT_ASSERT(!nf_ct_is_confirmed(ct)); + + if (!ct->ext) + return nf_ct_ext_create(&ct->ext, id, gfp); + + if (nf_ct_ext_exist(ct, id)) + return NULL; + + rcu_read_lock(); + t = rcu_dereference(nf_ct_ext_types[id]); + BUG_ON(t == NULL); + + newoff = ALIGN(ct->ext->len, t->align); + newlen = newoff + t->len; + rcu_read_unlock(); + + new = __krealloc(ct->ext, newlen, gfp); + if (!new) + return NULL; + + if (new != ct->ext) { + for (i = 0; i < NF_CT_EXT_NUM; i++) { + if (!nf_ct_ext_exist(ct, i)) + continue; + + rcu_read_lock(); + t = rcu_dereference(nf_ct_ext_types[i]); + if (t && t->move) + t->move((void *)new + new->offset[i], + (void *)ct->ext + ct->ext->offset[i]); + rcu_read_unlock(); + } + call_rcu(&ct->ext->rcu, __nf_ct_ext_free_rcu); + ct->ext = new; + } + + new->offset[id] = newoff; + new->len = newlen; + memset((void *)new + newoff, 0, newlen - newoff); + return (void *)new + newoff; +} +EXPORT_SYMBOL(__nf_ct_ext_add); + +static void update_alloc_size(struct nf_ct_ext_type *type) +{ + int i, j; + struct nf_ct_ext_type *t1, *t2; + enum nf_ct_ext_id min = 0, max = NF_CT_EXT_NUM - 1; + + /* unnecessary to update all types */ + if ((type->flags & NF_CT_EXT_F_PREALLOC) == 0) { + min = type->id; + max = type->id; + } + + /* This assumes that extended areas in conntrack for the types + whose NF_CT_EXT_F_PREALLOC bit set are allocated in order */ + for (i = min; i <= max; i++) { + t1 = nf_ct_ext_types[i]; + if (!t1) + continue; + + t1->alloc_size = sizeof(struct nf_ct_ext) + + ALIGN(sizeof(struct nf_ct_ext), t1->align) + + t1->len; + for (j = 0; j < NF_CT_EXT_NUM; j++) { + t2 = nf_ct_ext_types[j]; + if (t2 == NULL || t2 == t1 || + (t2->flags & NF_CT_EXT_F_PREALLOC) == 0) + continue; + + t1->alloc_size = ALIGN(t1->alloc_size, t2->align) + + t2->len; + } + } +} + +/* This MUST be called in process context. */ +int nf_ct_extend_register(struct nf_ct_ext_type *type) +{ + int ret = 0; + + mutex_lock(&nf_ct_ext_type_mutex); + if (nf_ct_ext_types[type->id]) { + ret = -EBUSY; + goto out; + } + + /* This ensures that nf_ct_ext_create() can allocate enough area + before updating alloc_size */ + type->alloc_size = ALIGN(sizeof(struct nf_ct_ext), type->align) + + type->len; + rcu_assign_pointer(nf_ct_ext_types[type->id], type); + update_alloc_size(type); +out: + mutex_unlock(&nf_ct_ext_type_mutex); + return ret; +} +EXPORT_SYMBOL_GPL(nf_ct_extend_register); + +/* This MUST be called in process context. */ +void nf_ct_extend_unregister(struct nf_ct_ext_type *type) +{ + mutex_lock(&nf_ct_ext_type_mutex); + rcu_assign_pointer(nf_ct_ext_types[type->id], NULL); + update_alloc_size(type); + mutex_unlock(&nf_ct_ext_type_mutex); + synchronize_rcu(); +} +EXPORT_SYMBOL_GPL(nf_ct_extend_unregister); 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