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221 lines
4.8 KiB
221 lines
4.8 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* GRE over IPv4 demultiplexer driver |
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* |
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* Authors: Dmitry Kozlov ([email protected]) |
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*/ |
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
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#include <linux/module.h> |
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#include <linux/if.h> |
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#include <linux/icmp.h> |
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#include <linux/kernel.h> |
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#include <linux/kmod.h> |
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#include <linux/skbuff.h> |
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#include <linux/in.h> |
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#include <linux/ip.h> |
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#include <linux/netdevice.h> |
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#include <linux/if_tunnel.h> |
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#include <linux/spinlock.h> |
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#include <net/protocol.h> |
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#include <net/gre.h> |
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#include <net/erspan.h> |
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#include <net/icmp.h> |
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#include <net/route.h> |
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#include <net/xfrm.h> |
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static const struct gre_protocol __rcu *gre_proto[GREPROTO_MAX] __read_mostly; |
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int gre_add_protocol(const struct gre_protocol *proto, u8 version) |
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{ |
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if (version >= GREPROTO_MAX) |
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return -EINVAL; |
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return (cmpxchg((const struct gre_protocol **)&gre_proto[version], NULL, proto) == NULL) ? |
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0 : -EBUSY; |
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} |
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EXPORT_SYMBOL_GPL(gre_add_protocol); |
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int gre_del_protocol(const struct gre_protocol *proto, u8 version) |
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{ |
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int ret; |
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if (version >= GREPROTO_MAX) |
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return -EINVAL; |
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ret = (cmpxchg((const struct gre_protocol **)&gre_proto[version], proto, NULL) == proto) ? |
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0 : -EBUSY; |
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if (ret) |
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return ret; |
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synchronize_rcu(); |
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return 0; |
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} |
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EXPORT_SYMBOL_GPL(gre_del_protocol); |
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/* Fills in tpi and returns header length to be pulled. |
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* Note that caller must use pskb_may_pull() before pulling GRE header. |
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*/ |
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int gre_parse_header(struct sk_buff *skb, struct tnl_ptk_info *tpi, |
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bool *csum_err, __be16 proto, int nhs) |
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{ |
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const struct gre_base_hdr *greh; |
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__be32 *options; |
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int hdr_len; |
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if (unlikely(!pskb_may_pull(skb, nhs + sizeof(struct gre_base_hdr)))) |
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return -EINVAL; |
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greh = (struct gre_base_hdr *)(skb->data + nhs); |
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if (unlikely(greh->flags & (GRE_VERSION | GRE_ROUTING))) |
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return -EINVAL; |
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tpi->flags = gre_flags_to_tnl_flags(greh->flags); |
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hdr_len = gre_calc_hlen(tpi->flags); |
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if (!pskb_may_pull(skb, nhs + hdr_len)) |
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return -EINVAL; |
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greh = (struct gre_base_hdr *)(skb->data + nhs); |
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tpi->proto = greh->protocol; |
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options = (__be32 *)(greh + 1); |
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if (greh->flags & GRE_CSUM) { |
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if (!skb_checksum_simple_validate(skb)) { |
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skb_checksum_try_convert(skb, IPPROTO_GRE, |
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null_compute_pseudo); |
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} else if (csum_err) { |
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*csum_err = true; |
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return -EINVAL; |
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} |
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options++; |
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} |
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if (greh->flags & GRE_KEY) { |
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tpi->key = *options; |
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options++; |
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} else { |
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tpi->key = 0; |
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} |
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if (unlikely(greh->flags & GRE_SEQ)) { |
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tpi->seq = *options; |
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options++; |
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} else { |
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tpi->seq = 0; |
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} |
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/* WCCP version 1 and 2 protocol decoding. |
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* - Change protocol to IPv4/IPv6 |
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* - When dealing with WCCPv2, Skip extra 4 bytes in GRE header |
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*/ |
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if (greh->flags == 0 && tpi->proto == htons(ETH_P_WCCP)) { |
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u8 _val, *val; |
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val = skb_header_pointer(skb, nhs + hdr_len, |
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sizeof(_val), &_val); |
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if (!val) |
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return -EINVAL; |
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tpi->proto = proto; |
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if ((*val & 0xF0) != 0x40) |
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hdr_len += 4; |
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} |
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tpi->hdr_len = hdr_len; |
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/* ERSPAN ver 1 and 2 protocol sets GRE key field |
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* to 0 and sets the configured key in the |
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* inner erspan header field |
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*/ |
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if ((greh->protocol == htons(ETH_P_ERSPAN) && hdr_len != 4) || |
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greh->protocol == htons(ETH_P_ERSPAN2)) { |
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struct erspan_base_hdr *ershdr; |
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if (!pskb_may_pull(skb, nhs + hdr_len + sizeof(*ershdr))) |
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return -EINVAL; |
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ershdr = (struct erspan_base_hdr *)(skb->data + nhs + hdr_len); |
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tpi->key = cpu_to_be32(get_session_id(ershdr)); |
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} |
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return hdr_len; |
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} |
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EXPORT_SYMBOL(gre_parse_header); |
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static int gre_rcv(struct sk_buff *skb) |
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{ |
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const struct gre_protocol *proto; |
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u8 ver; |
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int ret; |
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if (!pskb_may_pull(skb, 12)) |
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goto drop; |
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ver = skb->data[1]&0x7f; |
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if (ver >= GREPROTO_MAX) |
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goto drop; |
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rcu_read_lock(); |
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proto = rcu_dereference(gre_proto[ver]); |
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if (!proto || !proto->handler) |
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goto drop_unlock; |
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ret = proto->handler(skb); |
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rcu_read_unlock(); |
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return ret; |
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drop_unlock: |
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rcu_read_unlock(); |
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drop: |
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kfree_skb(skb); |
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return NET_RX_DROP; |
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} |
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static int gre_err(struct sk_buff *skb, u32 info) |
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{ |
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const struct gre_protocol *proto; |
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const struct iphdr *iph = (const struct iphdr *)skb->data; |
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u8 ver = skb->data[(iph->ihl<<2) + 1]&0x7f; |
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int err = 0; |
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if (ver >= GREPROTO_MAX) |
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return -EINVAL; |
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rcu_read_lock(); |
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proto = rcu_dereference(gre_proto[ver]); |
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if (proto && proto->err_handler) |
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proto->err_handler(skb, info); |
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else |
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err = -EPROTONOSUPPORT; |
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rcu_read_unlock(); |
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return err; |
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} |
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static const struct net_protocol net_gre_protocol = { |
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.handler = gre_rcv, |
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.err_handler = gre_err, |
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}; |
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static int __init gre_init(void) |
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{ |
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pr_info("GRE over IPv4 demultiplexor driver\n"); |
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if (inet_add_protocol(&net_gre_protocol, IPPROTO_GRE) < 0) { |
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pr_err("can't add protocol\n"); |
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return -EAGAIN; |
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} |
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return 0; |
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} |
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static void __exit gre_exit(void) |
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{ |
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inet_del_protocol(&net_gre_protocol, IPPROTO_GRE); |
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} |
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module_init(gre_init); |
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module_exit(gre_exit); |
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MODULE_DESCRIPTION("GRE over IPv4 demultiplexer driver"); |
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MODULE_AUTHOR("D. Kozlov ([email protected])"); |
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MODULE_LICENSE("GPL");
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