compat: support 3.10

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

3 files changed, 106 insertions, 5 deletions

diff --git a/src/compat/compat.h b/src/compat/compat.h
index a586b93..d936582 100644
--- a/src/compat/compat.h
+++ b/src/compat/compat.h
@@ -7,8 +7,8 @@
 #include <linux/version.h>
 #include <linux/types.h>
 
-#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 12, 0)
-#error "WireGuard requires Linux >= 3.12"
+#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 10, 0)
+#error "WireGuard requires Linux >= 3.10"
 #endif
 
 /* These conditionals can't be enforced by an out of tree module very easily,
@@ -53,7 +53,9 @@
     (LINUX_VERSION_CODE < KERNEL_VERSION(4, 1, 17) && LINUX_VERSION_CODE > KERNEL_VERSION(3, 19, 0)) || \
     (LINUX_VERSION_CODE < KERNEL_VERSION(3, 18, 27) && LINUX_VERSION_CODE >= KERNEL_VERSION(3, 17, 0)) || \
     (LINUX_VERSION_CODE < KERNEL_VERSION(3, 16, 8) && LINUX_VERSION_CODE >= KERNEL_VERSION(3, 15, 0)) || \
-    (LINUX_VERSION_CODE < KERNEL_VERSION(3, 14, 40) && LINUX_VERSION_CODE >= KERNEL_VERSION(3, 13, 0))
+    (LINUX_VERSION_CODE < KERNEL_VERSION(3, 14, 40) && LINUX_VERSION_CODE >= KERNEL_VERSION(3, 13, 0)) || \
+    (LINUX_VERSION_CODE < KERNEL_VERSION(3, 12, 54))
+
 #include <linux/if.h>
 #include <net/ip_tunnels.h>
 #define IP6_ECN_set_ce(a, b) IP6_ECN_set_ce(b)
@@ -66,6 +68,20 @@
 #define time_is_after_eq_jiffies64(a) time_before_eq64(get_jiffies_64(), a)
 #endif
 
+#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 12, 0) && IS_ENABLED(CONFIG_IPV6)
+#include <net/ipv6.h>
+struct ipv6_stub_type {
+	void *udpv6_encap_enable;
+	int (*ipv6_dst_lookup)(struct sock *sk, struct dst_entry **dst, struct flowi6 *fl6);
+};
+static const struct ipv6_stub_type ipv6_stub_impl = {
+	.udpv6_encap_enable = (void *)1,
+	.ipv6_dst_lookup = ip6_dst_lookup
+};
+static const struct ipv6_stub_type *ipv6_stub = &ipv6_stub_impl;
+#endif
+
+
 #if LINUX_VERSION_CODE < KERNEL_VERSION(4, 8, 0) && IS_ENABLED(CONFIG_IPV6)
 #include <net/addrconf.h>
 static inline bool ipv6_mod_enabled(void)
@@ -142,6 +158,46 @@ static inline void *our_pskb_put(struct sk_buff *skb, struct sk_buff *tail, int
 #define pskb_put our_pskb_put
 #endif
 
+#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 11, 0)
+#include <net/xfrm.h>
+static inline void skb_scrub_packet(struct sk_buff *skb, bool xnet)
+{
+	skb->tstamp.tv64 = 0;
+	skb->pkt_type = PACKET_HOST;
+	skb->skb_iif = 0;
+	skb_dst_drop(skb);
+	secpath_reset(skb);
+	nf_reset(skb);
+	nf_reset_trace(skb);
+	if (!xnet)
+		return;
+	skb_orphan(skb);
+	skb->mark = 0;
+}
+#endif
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 12, 0)
+#include <linux/random.h>
+static inline u32 prandom_u32_max(u32 ep_ro)
+{
+	return (u32)(((u64) prandom_u32() * ep_ro) >> 32);
+}
+#endif
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 12, 59)
+static inline int crypto_memneq(const void *a, const void *b, size_t size)
+{
+	unsigned long neq = 0;
+	while (size > 0) {
+		neq |= *(unsigned char *)a ^ *(unsigned char *)b;
+		a += 1;
+		b += 1;
+		size -= 1;
+	}
+	return neq != 0UL ? 1 : 0;
+}
+#endif
+
 /* https://lkml.org/lkml/2015/6/12/415 */
 #include <linux/netdevice.h>
 static inline struct net_device *netdev_pub(void *dev)
diff --git a/src/compat/udp_tunnel/udp_tunnel.c b/src/compat/udp_tunnel/udp_tunnel.c
index 58ac61c..2c60681 100644
--- a/src/compat/udp_tunnel/udp_tunnel.c
+++ b/src/compat/udp_tunnel/udp_tunnel.c
@@ -9,6 +9,12 @@
 #include <net/udp.h>
 #include <net/udp_tunnel.h>
 
+#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 12, 0)
+#define __sk_user_data(sk) ((*((void __rcu **)&(sk)->sk_user_data)))
+#define rcu_dereference_sk_user_data(sk) rcu_dereference(__sk_user_data((sk)))
+#define rcu_assign_sk_user_data(sk, ptr) rcu_assign_pointer(__sk_user_data((sk)), ptr)
+#endif
+
 /* This is global so, uh, only one real call site... This is the kind of horrific hack you'd expect to see in compat code. */
 static udp_tunnel_encap_rcv_t encap_rcv = NULL;
 static void our_sk_data_ready(struct sock *sk
@@ -129,6 +135,45 @@ static void fake_destructor(struct sk_buff *skb)
 {
 }
 
+#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 12, 0)
+static int our_iptunnel_xmit(struct rtable *rt, struct sk_buff *skb,
+		  __be32 src, __be32 dst, __u8 proto,
+		  __u8 tos, __u8 ttl, __be16 df, bool xnet)
+{
+	int pkt_len = skb->len;
+	struct iphdr *iph;
+	int err;
+
+	skb_scrub_packet(skb, xnet);
+
+	skb->rxhash = 0;
+	skb_dst_set(skb, &rt->dst);
+	memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
+
+	/* Push down and install the IP header. */
+	skb_push(skb, sizeof(struct iphdr));
+	skb_reset_network_header(skb);
+
+	iph = ip_hdr(skb);
+
+	iph->version	=	4;
+	iph->ihl	=	sizeof(struct iphdr) >> 2;
+	iph->frag_off	=	df;
+	iph->protocol	=	proto;
+	iph->tos	=	tos;
+	iph->daddr	=	dst;
+	iph->saddr	=	src;
+	iph->ttl	=	ttl;
+	__ip_select_ident(iph, skb_shinfo(skb)->gso_segs ?: 1);
+
+	err = ip_local_out(skb);
+	if (unlikely(net_xmit_eval(err)))
+		pkt_len = 0;
+	return pkt_len;
+}
+#define iptunnel_xmit our_iptunnel_xmit
+#endif
+
 void udp_tunnel_xmit_skb(struct rtable *rt, struct sock *sk, struct sk_buff *skb,
 			 __be32 src, __be32 dst, __u8 tos, __u8 ttl,
 			 __be16 df, __be16 src_port, __be16 dst_port,
diff --git a/src/dkms.conf b/src/dkms.conf
index 2e66bc9..2b854ba 100644
--- a/src/dkms.conf
+++ b/src/dkms.conf
@@ -5,5 +5,5 @@ AUTOINSTALL=yes
 BUILT_MODULE_NAME="wireguard"
 DEST_MODULE_LOCATION="/kernel/net"
 
-# requires kernel 3.12 or greater:
-BUILD_EXCLUSIVE_KERNEL="^(([^1230]\.)|(3\.1[23456789]))"
+# requires kernel 3.10 or greater:
+BUILD_EXCLUSIVE_KERNEL="^(([^1230]\.)|(3\.1[0-9]))"