compat: support 3.12

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

1 files changed, 201 insertions, 0 deletions

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;
+}