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

[Jeff Layton <jlayton@redhat.com>]

On Fri, 2016-10-07 at 11:01 +0100, Stefan Hajnoczi wrote:
> 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);
> +

Ick, what if I have a host on the network named "vsock"? I think you'll
need to come up with a different way to do this.

>  	for (i = 0; i < buflen; i++)
>  		if (buf[i] == ':')
>  			return rpc_pton6(net, buf, buflen, sap, salen);

-- 
Jeff Layton <jlayton@redhat.com>