compat: support 3.12

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

6 files changed, 237 insertions, 5 deletions

diff --git a/src/compat/Kbuild.include b/src/compat/Kbuild.include
index ebd5aaf..aaaffcb 100644
--- a/src/compat/Kbuild.include
+++ b/src/compat/Kbuild.include
@@ -15,7 +15,11 @@ wireguard-y += compat/dst_cache/dst_cache.o
 endif
 
 ifeq ($(wildcard $(srctree)/arch/x86/include/asm/fpu/api.h),)
-ccflags-y += -I$(src)/compat/i387/include
+ccflags-y += -I$(src)/compat/fpu/include
+endif
+
+ifeq ($(wildcard $(srctree)/arch/x86/include/asm/simd.h),)
+ccflags-y += -I$(src)/compat/simd/include
 endif
 
 ifeq ($(wildcard $(srctree)/include/net/udp_tunnel.h),)
diff --git a/src/compat/checksum/checksum_partial_compat.h b/src/compat/checksum/checksum_partial_compat.h
new file mode 100644
index 0000000..5175d84
--- /dev/null
+++ b/src/compat/checksum/checksum_partial_compat.h
@@ -0,0 +1,201 @@
+#include <net/route.h>
+#include <net/esp.h>
+#include <net/ip.h>
+#include <net/ipv6.h>
+#define IP6_MF          0x0001
+#define IP6_OFFSET      0xFFF8
+static inline int skb_maybe_pull_tail(struct sk_buff *skb, unsigned int len, unsigned int max)
+{
+	if (skb_headlen(skb) >= len)
+		return 0;
+	if (max > skb->len)
+		max = skb->len;
+	if (__pskb_pull_tail(skb, max - skb_headlen(skb)) == NULL)
+		return -ENOMEM;
+	if (skb_headlen(skb) < len)
+		return -EPROTO;
+	return 0;
+}
+#define MAX_IP_HDR_LEN 128
+static inline int skb_checksum_setup_ip(struct sk_buff *skb, bool recalculate)
+{
+	unsigned int off;
+	bool fragment;
+	int err;
+	fragment = false;
+	err = skb_maybe_pull_tail(skb, sizeof(struct iphdr), MAX_IP_HDR_LEN);
+	if (err < 0)
+		goto out;
+	if (ip_hdr(skb)->frag_off & htons(IP_OFFSET | IP_MF))
+		fragment = true;
+	off = ip_hdrlen(skb);
+	err = -EPROTO;
+	if (fragment)
+		goto out;
+	switch (ip_hdr(skb)->protocol) {
+	case IPPROTO_TCP:
+		err = skb_maybe_pull_tail(skb,
+					  off + sizeof(struct tcphdr),
+					  MAX_IP_HDR_LEN);
+		if (err < 0)
+			goto out;
+
+		if (!skb_partial_csum_set(skb, off,
+					  offsetof(struct tcphdr, check))) {
+			err = -EPROTO;
+			goto out;
+		}
+
+		if (recalculate)
+			tcp_hdr(skb)->check =
+				~csum_tcpudp_magic(ip_hdr(skb)->saddr,
+						   ip_hdr(skb)->daddr,
+						   skb->len - off,
+						   IPPROTO_TCP, 0);
+		break;
+	case IPPROTO_UDP:
+		err = skb_maybe_pull_tail(skb,
+					  off + sizeof(struct udphdr),
+					  MAX_IP_HDR_LEN);
+		if (err < 0)
+			goto out;
+
+		if (!skb_partial_csum_set(skb, off,
+					  offsetof(struct udphdr, check))) {
+			err = -EPROTO;
+			goto out;
+		}
+
+		if (recalculate)
+			udp_hdr(skb)->check =
+				~csum_tcpudp_magic(ip_hdr(skb)->saddr,
+						   ip_hdr(skb)->daddr,
+						   skb->len - off,
+						   IPPROTO_UDP, 0);
+		break;
+	default:
+		goto out;
+	}
+	err = 0;
+out:
+	return err;
+}
+#define MAX_IPV6_HDR_LEN 256
+#define OPT_HDR(type, skb, off) \
+	(type *)(skb_network_header(skb) + (off))
+static inline int skb_checksum_setup_ipv6(struct sk_buff *skb, bool recalculate)
+{
+	int err;
+	u8 nexthdr;
+	unsigned int off;
+	unsigned int len;
+	bool fragment;
+	bool done;
+	fragment = false;
+	done = false;
+	off = sizeof(struct ipv6hdr);
+	err = skb_maybe_pull_tail(skb, off, MAX_IPV6_HDR_LEN);
+	if (err < 0)
+		goto out;
+	nexthdr = ipv6_hdr(skb)->nexthdr;
+	len = sizeof(struct ipv6hdr) + ntohs(ipv6_hdr(skb)->payload_len);
+	while (off <= len && !done) {
+		switch (nexthdr) {
+		case IPPROTO_DSTOPTS:
+		case IPPROTO_HOPOPTS:
+		case IPPROTO_ROUTING: {
+			struct ipv6_opt_hdr *hp;
+
+			err = skb_maybe_pull_tail(skb, off + sizeof(struct ipv6_opt_hdr), MAX_IPV6_HDR_LEN);
+			if (err < 0)
+				goto out;
+			hp = OPT_HDR(struct ipv6_opt_hdr, skb, off);
+			nexthdr = hp->nexthdr;
+			off += ipv6_optlen(hp);
+			break;
+		}
+		case IPPROTO_FRAGMENT: {
+			struct frag_hdr *hp;
+			err = skb_maybe_pull_tail(skb, off + sizeof(struct frag_hdr), MAX_IPV6_HDR_LEN);
+			if (err < 0)
+				goto out;
+			hp = OPT_HDR(struct frag_hdr, skb, off);
+			if (hp->frag_off & htons(IP6_OFFSET | IP6_MF))
+				fragment = true;
+			nexthdr = hp->nexthdr;
+			off += sizeof(struct frag_hdr);
+			break;
+		}
+		default:
+			done = true;
+			break;
+		}
+	}
+	err = -EPROTO;
+	if (!done || fragment)
+		goto out;
+	switch (nexthdr) {
+		case IPPROTO_TCP:
+			err = skb_maybe_pull_tail(skb,
+						  off + sizeof(struct tcphdr),
+						  MAX_IPV6_HDR_LEN);
+			if (err < 0)
+				goto out;
+
+			if (!skb_partial_csum_set(skb, off,
+						  offsetof(struct tcphdr, check))) {
+				err = -EPROTO;
+				goto out;
+			}
+
+			if (recalculate)
+				tcp_hdr(skb)->check =
+					~csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
+							 &ipv6_hdr(skb)->daddr,
+							 skb->len - off,
+							 IPPROTO_TCP, 0);
+			break;
+		case IPPROTO_UDP:
+			err = skb_maybe_pull_tail(skb,
+						  off + sizeof(struct udphdr),
+						  MAX_IPV6_HDR_LEN);
+			if (err < 0)
+				goto out;
+
+			if (!skb_partial_csum_set(skb, off,
+						  offsetof(struct udphdr, check))) {
+				err = -EPROTO;
+				goto out;
+			}
+
+			if (recalculate)
+				udp_hdr(skb)->check =
+					~csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
+							 &ipv6_hdr(skb)->daddr,
+							 skb->len - off,
+							 IPPROTO_UDP, 0);
+			break;
+		default:
+			goto out;
+	}
+	err = 0;
+out:
+	return err;
+}
+static inline int skb_checksum_setup(struct sk_buff *skb, bool recalculate)
+{
+	int err;
+	switch (skb->protocol) {
+	case htons(ETH_P_IP):
+		err = skb_checksum_setup_ip(skb, recalculate);
+		break;
+
+	case htons(ETH_P_IPV6):
+		err = skb_checksum_setup_ipv6(skb, recalculate);
+		break;
+	default:
+		err = -EPROTO;
+		break;
+	}
+	return err;
+}
diff --git a/src/compat/compat.h b/src/compat/compat.h
index 4f2acb9..a586b93 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, 14, 0)
-#error "WireGuard requires Linux >= 3.14"
+#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 12, 0)
+#error "WireGuard requires Linux >= 3.12"
 #endif
 
 /* These conditionals can't be enforced by an out of tree module very easily,
@@ -41,7 +41,7 @@
 #if (LINUX_VERSION_CODE > KERNEL_VERSION(3, 19, 0) && LINUX_VERSION_CODE < KERNEL_VERSION(3, 19, 6)) || \
     (LINUX_VERSION_CODE < KERNEL_VERSION(3, 18, 12) && 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)
 #define dev_recursion_level() 0
 #endif
 
@@ -110,7 +110,10 @@ static inline void netif_keep_dst(struct net_device *dev)
 }
 #endif
 
-#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 15, 0)
+#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 14, 0)
+#define pcpu_sw_netstats pcpu_tstats
+#define netdev_alloc_pcpu_stats alloc_percpu
+#elif LINUX_VERSION_CODE < KERNEL_VERSION(3, 15, 0)
 #define netdev_alloc_pcpu_stats(type)					\
 ({									\
 	typeof(type) __percpu *pcpu_stats = alloc_percpu(type);		\
@@ -126,6 +129,19 @@ static inline void netif_keep_dst(struct net_device *dev)
 })
 #endif
 
+#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 14, 0)
+#include "checksum/checksum_partial_compat.h"
+static inline void *our_pskb_put(struct sk_buff *skb, struct sk_buff *tail, int len)
+{
+	if (tail != skb) {
+		skb->data_len += len;
+		skb->len += len;
+	}
+	return skb_put(tail, len);
+}
+#define pskb_put our_pskb_put
+#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/i387/include/asm/fpu/api.h b/src/compat/fpu/include/asm/fpu/api.h
index f3f9117..f3f9117 100644
--- a/src/compat/i387/include/asm/fpu/api.h
+++ b/src/compat/fpu/include/asm/fpu/api.h
diff --git a/src/compat/simd/include/asm/simd.h b/src/compat/simd/include/asm/simd.h
new file mode 100644
index 0000000..f3f9117
--- /dev/null
+++ b/src/compat/simd/include/asm/simd.h
@@ -0,0 +1 @@
+#include <asm/i387.h>
diff --git a/src/compat/siphash/siphash.c b/src/compat/siphash/siphash.c
index 3ae58b4..1ebfd5e 100644
--- a/src/compat/siphash/siphash.c
+++ b/src/compat/siphash/siphash.c
@@ -13,6 +13,16 @@
 #include <linux/siphash.h>
 #include <asm/unaligned.h>
 
+#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 14, 0)
+#ifdef __LITTLE_ENDIAN
+ #define HASH_LEN_DECLARE u32 hash; u32 len;
+ #define bytemask_from_count(cnt)	(~(~0ul << (cnt)*8))
+#else
+ #define HASH_LEN_DECLARE u32 len; u32 hash;
+ #define bytemask_from_count(cnt)	(~(~0ul >> (cnt)*8))
+#endif
+#endif
+
 #if defined(CONFIG_DCACHE_WORD_ACCESS) && BITS_PER_LONG == 64
 #include <linux/dcache.h>
 #include <asm/word-at-a-time.h>