diff options
Diffstat (limited to 'net/netfilter/nfnetlink_cthelper.c')
| -rw-r--r-- | net/netfilter/nfnetlink_cthelper.c | 680 |
1 files changed, 680 insertions, 0 deletions
diff --git a/net/netfilter/nfnetlink_cthelper.c b/net/netfilter/nfnetlink_cthelper.c new file mode 100644 index 00000000000..9e287cb56a0 --- /dev/null +++ b/net/netfilter/nfnetlink_cthelper.c @@ -0,0 +1,680 @@ +/* + * (C) 2012 Pablo Neira Ayuso <pablo@netfilter.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 (or any later at your option). + * + * This software has been sponsored by Vyatta Inc. <http://www.vyatta.com> + */ +#include <linux/init.h> +#include <linux/module.h> +#include <linux/kernel.h> +#include <linux/skbuff.h> +#include <linux/netlink.h> +#include <linux/rculist.h> +#include <linux/slab.h> +#include <linux/types.h> +#include <linux/list.h> +#include <linux/errno.h> +#include <net/netlink.h> +#include <net/sock.h> + +#include <net/netfilter/nf_conntrack_helper.h> +#include <net/netfilter/nf_conntrack_expect.h> +#include <net/netfilter/nf_conntrack_ecache.h> + +#include <linux/netfilter/nfnetlink.h> +#include <linux/netfilter/nfnetlink_conntrack.h> +#include <linux/netfilter/nfnetlink_cthelper.h> + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>"); +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) +{ + int err; + struct nlattr *tb[NFCTH_TUPLE_MAX+1]; + + err = nla_parse_nested(tb, NFCTH_TUPLE_MAX, attr, nfnl_cthelper_tuple_pol); + if (err < 0) + return err; + + if (!tb[NFCTH_TUPLE_L3PROTONUM] || !tb[NFCTH_TUPLE_L4PROTONUM]) + return -EINVAL; + + tuple->src.l3num = ntohs(nla_get_be16(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 (attr == NULL) + return -EINVAL; + + 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) +{ + int err; + struct nlattr *tb[NFCTH_POLICY_MAX+1]; + + err = nla_parse_nested(tb, NFCTH_POLICY_MAX, attr, nfnl_cthelper_expect_pol); + if (err < 0) + return err; + + 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]; + + ret = nla_parse_nested(tb, NFCTH_POLICY_SET_MAX, attr, + nfnl_cthelper_expect_policy_set); + if (ret < 0) + return ret; + + 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; i<helper->expect_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; + 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, &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; i<helper->expect_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 portid, u32 seq, u32 type, + int event, struct nf_conntrack_helper *helper) +{ + struct nlmsghdr *nlh; + struct nfgenmsg *nfmsg; + unsigned int flags = portid ? NLM_F_MULTI : 0; + int status; + + event |= NFNL_SUBSYS_CTHELPER << 8; + nlh = nlmsg_put(skb, portid, 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; + + 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, + &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).portid, + 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 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, &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).portid, + 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).portid, + 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 *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, 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 *tmp; + int i; + + nfnetlink_subsys_unregister(&nfnl_cthelper_subsys); + + for (i=0; i<nf_ct_helper_hsize; i++) { + hlist_for_each_entry_safe(cur, tmp, &nf_ct_helper_hash[i], + hnode) { + /* skip non-userspace conntrack helpers. */ + if (!(cur->flags & NF_CT_HELPER_F_USERSPACE)) + continue; + + nf_conntrack_helper_unregister(cur); + } + } +} + +module_init(nfnl_cthelper_init); +module_exit(nfnl_cthelper_exit); |