diff options
Diffstat (limited to 'net/ipv4/gre_demux.c')
| -rw-r--r-- | net/ipv4/gre_demux.c | 221 |
1 files changed, 221 insertions, 0 deletions
diff --git a/net/ipv4/gre_demux.c b/net/ipv4/gre_demux.c new file mode 100644 index 000000000..cbb2b4bb0 --- /dev/null +++ b/net/ipv4/gre_demux.c @@ -0,0 +1,221 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * GRE over IPv4 demultiplexer driver + * + * Authors: Dmitry Kozlov (xeb@mail.ru) + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/module.h> +#include <linux/if.h> +#include <linux/icmp.h> +#include <linux/kernel.h> +#include <linux/kmod.h> +#include <linux/skbuff.h> +#include <linux/in.h> +#include <linux/ip.h> +#include <linux/netdevice.h> +#include <linux/if_tunnel.h> +#include <linux/spinlock.h> +#include <net/protocol.h> +#include <net/gre.h> +#include <net/erspan.h> + +#include <net/icmp.h> +#include <net/route.h> +#include <net/xfrm.h> + +static const struct gre_protocol __rcu *gre_proto[GREPROTO_MAX] __read_mostly; + +int gre_add_protocol(const struct gre_protocol *proto, u8 version) +{ + if (version >= GREPROTO_MAX) + return -EINVAL; + + return (cmpxchg((const struct gre_protocol **)&gre_proto[version], NULL, proto) == NULL) ? + 0 : -EBUSY; +} +EXPORT_SYMBOL_GPL(gre_add_protocol); + +int gre_del_protocol(const struct gre_protocol *proto, u8 version) +{ + int ret; + + if (version >= GREPROTO_MAX) + return -EINVAL; + + ret = (cmpxchg((const struct gre_protocol **)&gre_proto[version], proto, NULL) == proto) ? + 0 : -EBUSY; + + if (ret) + return ret; + + synchronize_rcu(); + return 0; +} +EXPORT_SYMBOL_GPL(gre_del_protocol); + +/* Fills in tpi and returns header length to be pulled. + * Note that caller must use pskb_may_pull() before pulling GRE header. + */ +int gre_parse_header(struct sk_buff *skb, struct tnl_ptk_info *tpi, + bool *csum_err, __be16 proto, int nhs) +{ + const struct gre_base_hdr *greh; + __be32 *options; + int hdr_len; + + if (unlikely(!pskb_may_pull(skb, nhs + sizeof(struct gre_base_hdr)))) + return -EINVAL; + + greh = (struct gre_base_hdr *)(skb->data + nhs); + if (unlikely(greh->flags & (GRE_VERSION | GRE_ROUTING))) + return -EINVAL; + + tpi->flags = gre_flags_to_tnl_flags(greh->flags); + hdr_len = gre_calc_hlen(tpi->flags); + + if (!pskb_may_pull(skb, nhs + hdr_len)) + return -EINVAL; + + greh = (struct gre_base_hdr *)(skb->data + nhs); + tpi->proto = greh->protocol; + + options = (__be32 *)(greh + 1); + if (greh->flags & GRE_CSUM) { + if (!skb_checksum_simple_validate(skb)) { + skb_checksum_try_convert(skb, IPPROTO_GRE, + null_compute_pseudo); + } else if (csum_err) { + *csum_err = true; + return -EINVAL; + } + + options++; + } + + if (greh->flags & GRE_KEY) { + tpi->key = *options; + options++; + } else { + tpi->key = 0; + } + if (unlikely(greh->flags & GRE_SEQ)) { + tpi->seq = *options; + options++; + } else { + tpi->seq = 0; + } + /* WCCP version 1 and 2 protocol decoding. + * - Change protocol to IPv4/IPv6 + * - When dealing with WCCPv2, Skip extra 4 bytes in GRE header + */ + if (greh->flags == 0 && tpi->proto == htons(ETH_P_WCCP)) { + u8 _val, *val; + + val = skb_header_pointer(skb, nhs + hdr_len, + sizeof(_val), &_val); + if (!val) + return -EINVAL; + tpi->proto = proto; + if ((*val & 0xF0) != 0x40) + hdr_len += 4; + } + tpi->hdr_len = hdr_len; + + /* ERSPAN ver 1 and 2 protocol sets GRE key field + * to 0 and sets the configured key in the + * inner erspan header field + */ + if ((greh->protocol == htons(ETH_P_ERSPAN) && hdr_len != 4) || + greh->protocol == htons(ETH_P_ERSPAN2)) { + struct erspan_base_hdr *ershdr; + + if (!pskb_may_pull(skb, nhs + hdr_len + sizeof(*ershdr))) + return -EINVAL; + + ershdr = (struct erspan_base_hdr *)(skb->data + nhs + hdr_len); + tpi->key = cpu_to_be32(get_session_id(ershdr)); + } + + return hdr_len; +} +EXPORT_SYMBOL(gre_parse_header); + +static int gre_rcv(struct sk_buff *skb) +{ + const struct gre_protocol *proto; + u8 ver; + int ret; + + if (!pskb_may_pull(skb, 12)) + goto drop; + + ver = skb->data[1]&0x7f; + if (ver >= GREPROTO_MAX) + goto drop; + + rcu_read_lock(); + proto = rcu_dereference(gre_proto[ver]); + if (!proto || !proto->handler) + goto drop_unlock; + ret = proto->handler(skb); + rcu_read_unlock(); + return ret; + +drop_unlock: + rcu_read_unlock(); +drop: + kfree_skb(skb); + return NET_RX_DROP; +} + +static int gre_err(struct sk_buff *skb, u32 info) +{ + const struct gre_protocol *proto; + const struct iphdr *iph = (const struct iphdr *)skb->data; + u8 ver = skb->data[(iph->ihl<<2) + 1]&0x7f; + int err = 0; + + if (ver >= GREPROTO_MAX) + return -EINVAL; + + rcu_read_lock(); + proto = rcu_dereference(gre_proto[ver]); + if (proto && proto->err_handler) + proto->err_handler(skb, info); + else + err = -EPROTONOSUPPORT; + rcu_read_unlock(); + + return err; +} + +static const struct net_protocol net_gre_protocol = { + .handler = gre_rcv, + .err_handler = gre_err, +}; + +static int __init gre_init(void) +{ + pr_info("GRE over IPv4 demultiplexor driver\n"); + + if (inet_add_protocol(&net_gre_protocol, IPPROTO_GRE) < 0) { + pr_err("can't add protocol\n"); + return -EAGAIN; + } + return 0; +} + +static void __exit gre_exit(void) +{ + inet_del_protocol(&net_gre_protocol, IPPROTO_GRE); +} + +module_init(gre_init); +module_exit(gre_exit); + +MODULE_DESCRIPTION("GRE over IPv4 demultiplexer driver"); +MODULE_AUTHOR("D. Kozlov (xeb@mail.ru)"); +MODULE_LICENSE("GPL"); |