[PATCH v2 01/10] SUNRPC: add AF_VSOCK support to addr.[ch]

[Stefan Hajnoczi <stefanha@redhat.com>]

AF_VSOCK addresses are a Context ID (CID) and port number tuple.  The
CID is a unique address, similar to a IP address on a local subnet.

Extend the addr.h functions to handle AF_VSOCK addresses.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
v2:
 * Replace CONFIG_VSOCKETS with CONFIG_SUNRPC_XPRT_VSOCK to prevent
   build failures when SUNRPC=y and VSOCKETS=m.  Built-in code cannot
   link against code in a module.
---
 include/linux/sunrpc/addr.h | 44 ++++++++++++++++++++++++++++++++++
 net/sunrpc/Kconfig          | 10 ++++++++
 net/sunrpc/addr.c           | 57 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 111 insertions(+)

diff --git a/include/linux/sunrpc/addr.h b/include/linux/sunrpc/addr.h
index 5c9c6cd..c4169bc 100644
--- a/include/linux/sunrpc/addr.h
+++ b/include/linux/sunrpc/addr.h
@@ -10,6 +10,7 @@
 #include <linux/socket.h>
 #include <linux/in.h>
 #include <linux/in6.h>
+#include <linux/vm_sockets.h>
 #include <net/ipv6.h>
 
 size_t		rpc_ntop(const struct sockaddr *, char *, const size_t);
@@ -26,6 +27,8 @@ static inline unsigned short rpc_get_port(const struct sockaddr *sap)
 		return ntohs(((struct sockaddr_in *)sap)->sin_port);
 	case AF_INET6:
 		return ntohs(((struct sockaddr_in6 *)sap)->sin6_port);
+	case AF_VSOCK:
+		return ((struct sockaddr_vm *)sap)->svm_port;
 	}
 	return 0;
 }
@@ -40,6 +43,9 @@ static inline void rpc_set_port(struct sockaddr *sap,
 	case AF_INET6:
 		((struct sockaddr_in6 *)sap)->sin6_port = htons(port);
 		break;
+	case AF_VSOCK:
+		((struct sockaddr_vm *)sap)->svm_port = port;
+		break;
 	}
 }
 
@@ -106,6 +112,40 @@ static inline bool __rpc_copy_addr6(struct sockaddr *dst,
 }
 #endif	/* !(IS_ENABLED(CONFIG_IPV6) */
 
+#if IS_ENABLED(CONFIG_VSOCKETS)
+static inline bool rpc_cmp_vsock_addr(const struct sockaddr *sap1,
+				      const struct sockaddr *sap2)
+{
+	const struct sockaddr_vm *svm1 = (const struct sockaddr_vm *)sap1;
+	const struct sockaddr_vm *svm2 = (const struct sockaddr_vm *)sap2;
+
+	return svm1->svm_cid == svm2->svm_cid;
+}
+
+static inline bool __rpc_copy_vsock_addr(struct sockaddr *dst,
+					 const struct sockaddr *src)
+{
+	const struct sockaddr_vm *ssvm = (const struct sockaddr_vm *)src;
+	struct sockaddr_vm *dsvm = (struct sockaddr_vm *)dst;
+
+	dsvm->svm_family = ssvm->svm_family;
+	dsvm->svm_cid = ssvm->svm_cid;
+	return true;
+}
+#else	/* !(IS_ENABLED(CONFIG_VSOCKETS) */
+static inline bool rpc_cmp_vsock_addr(const struct sockaddr *sap1,
+				      const struct sockaddr *sap2)
+{
+	return false;
+}
+
+static inline bool __rpc_copy_vsock_addr(struct sockaddr *dst,
+					 const struct sockaddr *src)
+{
+	return false;
+}
+#endif	/* !(IS_ENABLED(CONFIG_VSOCKETS) */
+
 /**
  * rpc_cmp_addr - compare the address portion of two sockaddrs.
  * @sap1: first sockaddr
@@ -125,6 +165,8 @@ static inline bool rpc_cmp_addr(const struct sockaddr *sap1,
 			return rpc_cmp_addr4(sap1, sap2);
 		case AF_INET6:
 			return rpc_cmp_addr6(sap1, sap2);
+		case AF_VSOCK:
+			return rpc_cmp_vsock_addr(sap1, sap2);
 		}
 	}
 	return false;
@@ -161,6 +203,8 @@ static inline bool rpc_copy_addr(struct sockaddr *dst,
 		return __rpc_copy_addr4(dst, src);
 	case AF_INET6:
 		return __rpc_copy_addr6(dst, src);
+	case AF_VSOCK:
+		return __rpc_copy_vsock_addr(dst, src);
 	}
 	return false;
 }
diff --git a/net/sunrpc/Kconfig b/net/sunrpc/Kconfig
index 04ce2c0..d18fc1a 100644
--- a/net/sunrpc/Kconfig
+++ b/net/sunrpc/Kconfig
@@ -61,3 +61,13 @@ config SUNRPC_XPRT_RDMA
 
 	  If unsure, or you know there is no RDMA capability on your
 	  hardware platform, say N.
+
+config SUNRPC_XPRT_VSOCK
+	bool "RPC-over-AF_VSOCK transport"
+	depends on SUNRPC && VSOCKETS && !(SUNRPC=y && VSOCKETS=m)
+	default SUNRPC && VSOCKETS
+	help
+	  This option allows the NFS client and server to use the AF_VSOCK
+	  transport to communicate between virtual machines and the host.
+
+	  If unsure, say Y.
diff --git a/net/sunrpc/addr.c b/net/sunrpc/addr.c
index 2e0a6f9..f4dd962 100644
--- a/net/sunrpc/addr.c
+++ b/net/sunrpc/addr.c
@@ -16,11 +16,14 @@
  * RFC 4291, Section 2.2 for details on IPv6 presentation formats.
  */
 
+ /* TODO register netid and uaddr with IANA? (See RFC 5665 5.1/5.2) */
+
 #include <net/ipv6.h>
 #include <linux/sunrpc/addr.h>
 #include <linux/sunrpc/msg_prot.h>
 #include <linux/slab.h>
 #include <linux/export.h>
+#include <linux/vm_sockets.h>
 
 #if IS_ENABLED(CONFIG_IPV6)
 
@@ -108,6 +111,26 @@ static size_t rpc_ntop6(const struct sockaddr *sap,
 
 #endif	/* !IS_ENABLED(CONFIG_IPV6) */
 
+#ifdef CONFIG_SUNRPC_XPRT_VSOCK
+
+static size_t rpc_ntop_vsock(const struct sockaddr *sap,
+			     char *buf, const size_t buflen)
+{
+	const struct sockaddr_vm *svm = (struct sockaddr_vm *)sap;
+
+	return snprintf(buf, buflen, "%u", svm->svm_cid);
+}
+
+#else	/* !CONFIG_SUNRPC_XPRT_VSOCK */
+
+static size_t rpc_ntop_vsock(const struct sockaddr *sap,
+			     char *buf, const size_t buflen)
+{
+	return 0;
+}
+
+#endif	/* !CONFIG_SUNRPC_XPRT_VSOCK */
+
 static int rpc_ntop4(const struct sockaddr *sap,
 		     char *buf, const size_t buflen)
 {
@@ -132,6 +155,8 @@ size_t rpc_ntop(const struct sockaddr *sap, char *buf, const size_t buflen)
 		return rpc_ntop4(sap, buf, buflen);
 	case AF_INET6:
 		return rpc_ntop6(sap, buf, buflen);
+	case AF_VSOCK:
+		return rpc_ntop_vsock(sap, buf, buflen);
 	}
 
 	return 0;
@@ -229,6 +254,34 @@ static size_t rpc_pton6(struct net *net, const char *buf, const size_t buflen,
 }
 #endif
 
+#ifdef CONFIG_SUNRPC_XPRT_VSOCK
+static size_t rpc_pton_vsock(const char *buf, const size_t buflen,
+			     struct sockaddr *sap, const size_t salen)
+{
+	const size_t prefix_len = strlen("vsock:");
+	struct sockaddr_vm *svm = (struct sockaddr_vm *)sap;
+	unsigned int cid;
+
+	if (strncmp(buf, "vsock:", prefix_len) != 0 ||
+	    salen < sizeof(struct sockaddr_vm))
+		return 0;
+
+	if (kstrtouint(buf + prefix_len, 10, &cid) != 0)
+		return 0;
+
+	memset(svm, 0, sizeof(struct sockaddr_vm));
+	svm->svm_family = AF_VSOCK;
+	svm->svm_cid = cid;
+	return sizeof(struct sockaddr_vm);
+}
+#else
+static size_t rpc_pton_vsock(const char *buf, const size_t buflen,
+			     struct sockaddr *sap, const size_t salen)
+{
+	return 0;
+}
+#endif
+
 /**
  * rpc_pton - Construct a sockaddr in @sap
  * @net: applicable network namespace
@@ -249,6 +302,10 @@ size_t rpc_pton(struct net *net, const char *buf, const size_t buflen,
 {
 	unsigned int i;
 
+	/* TODO is there a nicer way to distinguish vsock addresses? */
+	if (strncmp(buf, "vsock:", 6) == 0)
+		return rpc_pton_vsock(buf, buflen, sap, salen);
+
 	for (i = 0; i < buflen; i++)
 		if (buf[i] == ':')
 			return rpc_pton6(net, buf, buflen, sap, salen);
-- 
2.7.4