--- /dev/null
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <linux/types.h>
+#include <linux/ip.h>
+#include <linux/netfilter.h>
+#include <linux/netfilter_ipv6.h>
+#include <linux/netfilter_bridge.h>
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/icmp.h>
+#include <linux/sysctl.h>
+#include <net/route.h>
+#include <net/ip.h>
+
+#include <net/netfilter/nf_conntrack.h>
+#include <net/netfilter/nf_conntrack_core.h>
+#include <net/netfilter/nf_conntrack_helper.h>
+#include <net/netfilter/nf_conntrack_bridge.h>
+
+#include <linux/netfilter/nf_tables.h>
+#include <net/netfilter/ipv6/nf_defrag_ipv6.h>
+#include <net/netfilter/nf_tables.h>
+
+#include "../br_private.h"
+
+/* Best effort variant of ip_do_fragment which preserves geometry, unless skbuff
+ * has been linearized or cloned.
+ */
+static int nf_br_ip_fragment(struct net *net, struct sock *sk,
+ struct sk_buff *skb,
+ struct nf_ct_bridge_frag_data *data,
+ int (*output)(struct net *, struct sock *sk,
+ const struct nf_ct_bridge_frag_data *data,
+ struct sk_buff *))
+{
+ int frag_max_size = BR_INPUT_SKB_CB(skb)->frag_max_size;
+ unsigned int hlen, ll_rs, mtu;
+ struct ip_frag_state state;
+ struct iphdr *iph;
+ int err;
+
+ /* for offloaded checksums cleanup checksum before fragmentation */
+ if (skb->ip_summed == CHECKSUM_PARTIAL &&
+ (err = skb_checksum_help(skb)))
+ goto blackhole;
+
+ iph = ip_hdr(skb);
+
+ /*
+ * Setup starting values
+ */
+
+ hlen = iph->ihl * 4;
+ frag_max_size -= hlen;
+ ll_rs = LL_RESERVED_SPACE(skb->dev);
+ mtu = skb->dev->mtu;
+
+ if (skb_has_frag_list(skb)) {
+ unsigned int first_len = skb_pagelen(skb);
+ struct ip_fraglist_iter iter;
+ struct sk_buff *frag;
+
+ if (first_len - hlen > mtu ||
+ skb_headroom(skb) < ll_rs)
+ goto blackhole;
+
+ if (skb_cloned(skb))
+ goto slow_path;
+
+ skb_walk_frags(skb, frag) {
+ if (frag->len > mtu ||
+ skb_headroom(frag) < hlen + ll_rs)
+ goto blackhole;
+
+ if (skb_shared(frag))
+ goto slow_path;
+ }
+
+ ip_fraglist_init(skb, iph, hlen, &iter);
+
+ for (;;) {
+ if (iter.frag)
+ ip_fraglist_prepare(skb, &iter);
+
+ err = output(net, sk, data, skb);
+ if (err || !iter.frag)
+ break;
+
+ skb = ip_fraglist_next(&iter);
+ }
+ return err;
+ }
+slow_path:
+ /* This is a linearized skbuff, the original geometry is lost for us.
+ * This may also be a clone skbuff, we could preserve the geometry for
+ * the copies but probably not worth the effort.
+ */
+ ip_frag_init(skb, hlen, ll_rs, frag_max_size, &state);
+
+ while (state.left > 0) {
+ struct sk_buff *skb2;
+
+ skb2 = ip_frag_next(skb, &state);
+ if (IS_ERR(skb2)) {
+ err = PTR_ERR(skb2);
+ goto blackhole;
+ }
+
+ err = output(net, sk, data, skb2);
+ if (err)
+ goto blackhole;
+ }
+ consume_skb(skb);
+ return err;
+
+blackhole:
+ kfree_skb(skb);
+ return 0;
+}
+
+/* ip_defrag() expects IPCB() in place. */
+static void br_skb_cb_save(struct sk_buff *skb, struct br_input_skb_cb *cb,
+ size_t inet_skb_parm_size)
+{
+ memcpy(cb, skb->cb, sizeof(*cb));
+ memset(skb->cb, 0, inet_skb_parm_size);
+}
+
+static void br_skb_cb_restore(struct sk_buff *skb,
+ const struct br_input_skb_cb *cb,
+ u16 fragsz)
+{
+ memcpy(skb->cb, cb, sizeof(*cb));
+ BR_INPUT_SKB_CB(skb)->frag_max_size = fragsz;
+}
+
+static unsigned int nf_ct_br_defrag4(struct sk_buff *skb,
+ const struct nf_hook_state *state)
+{
+ u16 zone_id = NF_CT_DEFAULT_ZONE_ID;
+ enum ip_conntrack_info ctinfo;
+ struct br_input_skb_cb cb;
+ const struct nf_conn *ct;
+ int err;
+
+ if (!ip_is_fragment(ip_hdr(skb)))
+ return NF_ACCEPT;
+
+ ct = nf_ct_get(skb, &ctinfo);
+ if (ct)
+ zone_id = nf_ct_zone_id(nf_ct_zone(ct), CTINFO2DIR(ctinfo));
+
+ br_skb_cb_save(skb, &cb, sizeof(struct inet_skb_parm));
+ local_bh_disable();
+ err = ip_defrag(state->net, skb,
+ IP_DEFRAG_CONNTRACK_BRIDGE_IN + zone_id);
+ local_bh_enable();
+ if (!err) {
+ br_skb_cb_restore(skb, &cb, IPCB(skb)->frag_max_size);
+ skb->ignore_df = 1;
+ return NF_ACCEPT;
+ }
+
+ return NF_STOLEN;
+}
+
+static int nf_ct_br_ip_check(const struct sk_buff *skb)
+{
+ const struct iphdr *iph;
+ int nhoff, len;
+
+ nhoff = skb_network_offset(skb);
+ iph = ip_hdr(skb);
+ if (iph->ihl < 5 ||
+ iph->version != 4)
+ return -1;
+
+ len = ntohs(iph->tot_len);
+ if (skb->len < nhoff + len ||
+ len < (iph->ihl * 4))
+ return -1;
+
+ return 0;
+}
+
+static unsigned int nf_ct_bridge_pre(void *priv, struct sk_buff *skb,
+ const struct nf_hook_state *state)
+{
+ struct nf_hook_state bridge_state = *state;
+ enum ip_conntrack_info ctinfo;
+ struct nf_conn *ct;
+ u32 len;
+ int ret;
+
+ ct = nf_ct_get(skb, &ctinfo);
+ if ((ct && !nf_ct_is_template(ct)) ||
+ ctinfo == IP_CT_UNTRACKED)
+ return NF_ACCEPT;
+
+ switch (skb->protocol) {
+ case htons(ETH_P_IP):
+ if (!pskb_may_pull(skb, sizeof(struct iphdr)))
+ return NF_ACCEPT;
+
+ len = ntohs(ip_hdr(skb)->tot_len);
+ if (pskb_trim_rcsum(skb, len))
+ return NF_ACCEPT;
+
+ if (nf_ct_br_ip_check(skb))
+ return NF_ACCEPT;
+
+ bridge_state.pf = NFPROTO_IPV4;
+ ret = nf_ct_br_defrag4(skb, &bridge_state);
+ break;
+ case htons(ETH_P_IPV6):
+ /* fall through */
+ default:
+ nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
+ return NF_ACCEPT;
+ }
+
+ if (ret != NF_ACCEPT)
+ return ret;
+
+ return nf_conntrack_in(skb, &bridge_state);
+}
+
+static void nf_ct_bridge_frag_save(struct sk_buff *skb,
+ struct nf_ct_bridge_frag_data *data)
+{
+ if (skb_vlan_tag_present(skb)) {
+ data->vlan_present = true;
+ data->vlan_tci = skb->vlan_tci;
+ data->vlan_proto = skb->vlan_proto;
+ } else {
+ data->vlan_present = false;
+ }
+ skb_copy_from_linear_data_offset(skb, -ETH_HLEN, data->mac, ETH_HLEN);
+}
+
+static unsigned int
+nf_ct_bridge_refrag(struct sk_buff *skb, const struct nf_hook_state *state,
+ int (*output)(struct net *, struct sock *sk,
+ const struct nf_ct_bridge_frag_data *data,
+ struct sk_buff *))
+{
+ struct nf_ct_bridge_frag_data data;
+
+ if (!BR_INPUT_SKB_CB(skb)->frag_max_size)
+ return NF_ACCEPT;
+
+ nf_ct_bridge_frag_save(skb, &data);
+ switch (skb->protocol) {
+ case htons(ETH_P_IP):
+ nf_br_ip_fragment(state->net, state->sk, skb, &data, output);
+ break;
+ case htons(ETH_P_IPV6):
+ return NF_ACCEPT;
+ default:
+ WARN_ON_ONCE(1);
+ return NF_DROP;
+ }
+
+ return NF_STOLEN;
+}
+
+/* Actually only slow path refragmentation needs this. */
+static int nf_ct_bridge_frag_restore(struct sk_buff *skb,
+ const struct nf_ct_bridge_frag_data *data)
+{
+ int err;
+
+ err = skb_cow_head(skb, ETH_HLEN);
+ if (err) {
+ kfree_skb(skb);
+ return -ENOMEM;
+ }
+ if (data->vlan_present)
+ __vlan_hwaccel_put_tag(skb, data->vlan_proto, data->vlan_tci);
+
+ skb_copy_to_linear_data_offset(skb, -ETH_HLEN, data->mac, ETH_HLEN);
+ skb_reset_mac_header(skb);
+
+ return 0;
+}
+
+static int nf_ct_bridge_refrag_post(struct net *net, struct sock *sk,
+ const struct nf_ct_bridge_frag_data *data,
+ struct sk_buff *skb)
+{
+ int err;
+
+ err = nf_ct_bridge_frag_restore(skb, data);
+ if (err < 0)
+ return err;
+
+ return br_dev_queue_push_xmit(net, sk, skb);
+}
+
+static unsigned int nf_ct_bridge_confirm(struct sk_buff *skb)
+{
+ enum ip_conntrack_info ctinfo;
+ struct nf_conn *ct;
+ int protoff;
+
+ ct = nf_ct_get(skb, &ctinfo);
+ if (!ct || ctinfo == IP_CT_RELATED_REPLY)
+ return nf_conntrack_confirm(skb);
+
+ switch (skb->protocol) {
+ case htons(ETH_P_IP):
+ protoff = skb_network_offset(skb) + ip_hdrlen(skb);
+ break;
+ case htons(ETH_P_IPV6): {
+ unsigned char pnum = ipv6_hdr(skb)->nexthdr;
+ __be16 frag_off;
+
+ protoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &pnum,
+ &frag_off);
+ if (protoff < 0 || (frag_off & htons(~0x7)) != 0)
+ return nf_conntrack_confirm(skb);
+ }
+ break;
+ default:
+ return NF_ACCEPT;
+ }
+ return nf_confirm(skb, protoff, ct, ctinfo);
+}
+
+static unsigned int nf_ct_bridge_post(void *priv, struct sk_buff *skb,
+ const struct nf_hook_state *state)
+{
+ int ret;
+
+ ret = nf_ct_bridge_confirm(skb);
+ if (ret != NF_ACCEPT)
+ return ret;
+
+ return nf_ct_bridge_refrag(skb, state, nf_ct_bridge_refrag_post);
+}
+
+static struct nf_hook_ops nf_ct_bridge_hook_ops[] __read_mostly = {
+ {
+ .hook = nf_ct_bridge_pre,
+ .pf = NFPROTO_BRIDGE,
+ .hooknum = NF_BR_PRE_ROUTING,
+ .priority = NF_IP_PRI_CONNTRACK,
+ },
+ {
+ .hook = nf_ct_bridge_post,
+ .pf = NFPROTO_BRIDGE,
+ .hooknum = NF_BR_POST_ROUTING,
+ .priority = NF_IP_PRI_CONNTRACK_CONFIRM,
+ },
+};
+
+static struct nf_ct_bridge_info bridge_info = {
+ .ops = nf_ct_bridge_hook_ops,
+ .ops_size = ARRAY_SIZE(nf_ct_bridge_hook_ops),
+ .me = THIS_MODULE,
+};
+
+static int __init nf_conntrack_l3proto_bridge_init(void)
+{
+ nf_ct_bridge_register(&bridge_info);
+
+ return 0;
+}
+
+static void __exit nf_conntrack_l3proto_bridge_fini(void)
+{
+ nf_ct_bridge_unregister(&bridge_info);
+}
+
+module_init(nf_conntrack_l3proto_bridge_init);
+module_exit(nf_conntrack_l3proto_bridge_fini);
+
+MODULE_ALIAS("nf_conntrack-" __stringify(AF_BRIDGE));
+MODULE_LICENSE("GPL");
projects / openwrt / staging / blogic.git / commitdiff