// SPDX-License-Identifier: GPL-2.0-or-later /* * net/sched/em_ipt.c IPtables matches Ematch * * (c) 2018 Eyal Birger <eyal.birger@gmail.com> */ #include <linux/gfp.h> #include <linux/module.h> #include <linux/types.h> #include <linux/kernel.h> #include <linux/string.h> #include <linux/skbuff.h> #include <linux/tc_ematch/tc_em_ipt.h> #include <linux/netfilter.h> #include <linux/netfilter/x_tables.h> #include <linux/netfilter_ipv4/ip_tables.h> #include <linux/netfilter_ipv6/ip6_tables.h> #include <net/pkt_cls.h> struct em_ipt_match { const struct xt_match *match; u32 hook; u8 nfproto; u8 match_data[] __aligned(8); }; struct em_ipt_xt_match { char *match_name; int (*validate_match_data)(struct nlattr **tb, u8 mrev); }; static const struct nla_policy em_ipt_policy[TCA_EM_IPT_MAX + 1] = { [TCA_EM_IPT_MATCH_NAME] = { .type = NLA_STRING, .len = XT_EXTENSION_MAXNAMELEN }, [TCA_EM_IPT_MATCH_REVISION] = { .type = NLA_U8 }, [TCA_EM_IPT_HOOK] = { .type = NLA_U32 }, [TCA_EM_IPT_NFPROTO] = { .type = NLA_U8 }, [TCA_EM_IPT_MATCH_DATA] = { .type = NLA_UNSPEC }, }; static int check_match(struct net *net, struct em_ipt_match *im, int mdata_len) { struct xt_mtchk_param mtpar = {}; union { struct ipt_entry e4; struct ip6t_entry e6; } e = {}; mtpar.net = net; mtpar.table = "filter"; mtpar.hook_mask = 1 << im->hook; mtpar.family = im->match->family; mtpar.match = im->match; mtpar.entryinfo = &e; mtpar.matchinfo = (void *)im->match_data; return xt_check_match(&mtpar, mdata_len, 0, 0); } static int policy_validate_match_data(struct nlattr **tb, u8 mrev) { if (mrev != 0) { pr_err("only policy match revision 0 supported"); return -EINVAL; } if (nla_get_u32(tb[TCA_EM_IPT_HOOK]) != NF_INET_PRE_ROUTING) { pr_err("policy can only be matched on NF_INET_PRE_ROUTING"); return -EINVAL; } return 0; } static int addrtype_validate_match_data(struct nlattr **tb, u8 mrev) { if (mrev != 1) { pr_err("only addrtype match revision 1 supported"); return -EINVAL; } return 0; } static const struct em_ipt_xt_match em_ipt_xt_matches[] = { { .match_name = "policy", .validate_match_data = policy_validate_match_data }, { .match_name = "addrtype", .validate_match_data = addrtype_validate_match_data }, {} }; static struct xt_match *get_xt_match(struct nlattr **tb) { const struct em_ipt_xt_match *m; struct nlattr *mname_attr; u8 nfproto, mrev = 0; int ret; mname_attr = tb[TCA_EM_IPT_MATCH_NAME]; for (m = em_ipt_xt_matches; m->match_name; m++) { if (!nla_strcmp(mname_attr, m->match_name)) break; } if (!m->match_name) { pr_err("Unsupported xt match"); return ERR_PTR(-EINVAL); } if (tb[TCA_EM_IPT_MATCH_REVISION]) mrev = nla_get_u8(tb[TCA_EM_IPT_MATCH_REVISION]); ret = m->validate_match_data(tb, mrev); if (ret < 0) return ERR_PTR(ret); nfproto = nla_get_u8(tb[TCA_EM_IPT_NFPROTO]); return xt_request_find_match(nfproto, m->match_name, mrev); } static int em_ipt_change(struct net *net, void *data, int data_len, struct tcf_ematch *em) { struct nlattr *tb[TCA_EM_IPT_MAX + 1]; struct em_ipt_match *im = NULL; struct xt_match *match; int mdata_len, ret; u8 nfproto; ret = nla_parse_deprecated(tb, TCA_EM_IPT_MAX, data, data_len, em_ipt_policy, NULL); if (ret < 0) return ret; if (!tb[TCA_EM_IPT_HOOK] || !tb[TCA_EM_IPT_MATCH_NAME] || !tb[TCA_EM_IPT_MATCH_DATA] || !tb[TCA_EM_IPT_NFPROTO]) return -EINVAL; nfproto = nla_get_u8(tb[TCA_EM_IPT_NFPROTO]); switch (nfproto) { case NFPROTO_IPV4: case NFPROTO_IPV6: break; default: return -EINVAL; } match = get_xt_match(tb); if (IS_ERR(match)) { pr_err("unable to load match\n"); return PTR_ERR(match); } mdata_len = XT_ALIGN(nla_len(tb[TCA_EM_IPT_MATCH_DATA])); im = kzalloc(sizeof(*im) + mdata_len, GFP_KERNEL); if (!im) { ret = -ENOMEM; goto err; } im->match = match; im->hook = nla_get_u32(tb[TCA_EM_IPT_HOOK]); im->nfproto = nfproto; nla_memcpy(im->match_data, tb[TCA_EM_IPT_MATCH_DATA], mdata_len); ret = check_match(net, im, mdata_len); if (ret) goto err; em->datalen = sizeof(*im) + mdata_len; em->data = (unsigned long)im; return 0; err: kfree(im); module_put(match->me); return ret; } static void em_ipt_destroy(struct tcf_ematch *em) { struct em_ipt_match *im = (void *)em->data; if (!im) return; if (im->match->destroy) { struct xt_mtdtor_param par = { .net = em->net, .match = im->match, .matchinfo = im->match_data, .family = im->match->family }; im->match->destroy(&par); } module_put(im->match->me); kfree(im); } static int em_ipt_match(struct sk_buff *skb, struct tcf_ematch *em, struct tcf_pkt_info *info) { const struct em_ipt_match *im = (const void *)em->data; struct xt_action_param acpar = {}; struct net_device *indev = NULL; u8 nfproto = im->match->family; struct nf_hook_state state; int ret; switch (skb_protocol(skb, true)) { case htons(ETH_P_IP): if (!pskb_network_may_pull(skb, sizeof(struct iphdr))) return 0; if (nfproto == NFPROTO_UNSPEC) nfproto = NFPROTO_IPV4; break; case htons(ETH_P_IPV6): if (!pskb_network_may_pull(skb, sizeof(struct ipv6hdr))) return 0; if (nfproto == NFPROTO_UNSPEC) nfproto = NFPROTO_IPV6; break; default: return 0; } rcu_read_lock(); if (skb->skb_iif) indev = dev_get_by_index_rcu(em->net, skb->skb_iif); nf_hook_state_init(&state, im->hook, nfproto, indev ?: skb->dev, skb->dev, NULL, em->net, NULL); acpar.match = im->match; acpar.matchinfo = im->match_data; acpar.state = &state; ret = im->match->match(skb, &acpar); rcu_read_unlock(); return ret; } static int em_ipt_dump(struct sk_buff *skb, struct tcf_ematch *em) { struct em_ipt_match *im = (void *)em->data; if (nla_put_string(skb, TCA_EM_IPT_MATCH_NAME, im->match->name) < 0) return -EMSGSIZE; if (nla_put_u32(skb, TCA_EM_IPT_HOOK, im->hook) < 0) return -EMSGSIZE; if (nla_put_u8(skb, TCA_EM_IPT_MATCH_REVISION, im->match->revision) < 0) return -EMSGSIZE; if (nla_put_u8(skb, TCA_EM_IPT_NFPROTO, im->nfproto) < 0) return -EMSGSIZE; if (nla_put(skb, TCA_EM_IPT_MATCH_DATA, im->match->usersize ?: im->match->matchsize, im->match_data) < 0) return -EMSGSIZE; return 0; } static struct tcf_ematch_ops em_ipt_ops = { .kind = TCF_EM_IPT, .change = em_ipt_change, .destroy = em_ipt_destroy, .match = em_ipt_match, .dump = em_ipt_dump, .owner = THIS_MODULE, .link = LIST_HEAD_INIT(em_ipt_ops.link) }; static int __init init_em_ipt(void) { return tcf_em_register(&em_ipt_ops); } static void __exit exit_em_ipt(void) { tcf_em_unregister(&em_ipt_ops); } MODULE_LICENSE("GPL"); MODULE_AUTHOR("Eyal Birger <eyal.birger@gmail.com>"); MODULE_DESCRIPTION("TC extended match for IPtables matches"); module_init(init_em_ipt); module_exit(exit_em_ipt); MODULE_ALIAS_TCF_EMATCH(TCF_EM_IPT);