Get the address family from h->connaddr instead. This should make no difference to existing code. --- generator/states-connect.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/generator/states-connect.c b/generator/states-connect.c index 04e894c..d62b0f5 100644 --- a/generator/states-connect.c +++ b/generator/states-connect.c @@ -51,7 +51,8 @@ STATE_MACHINE { int fd; assert (!h->sock); - fd = socket (AF_UNIX, SOCK_STREAM|SOCK_NONBLOCK|SOCK_CLOEXEC, 0); + fd = socket (h->connaddr.ss_family, + SOCK_STREAM|SOCK_NONBLOCK|SOCK_CLOEXEC, 0); if (fd == -1) { SET_NEXT_STATE (%.DEAD); set_error (errno, "socket"); -- 2.23.0

This adds a new API for connecting to AF_VSOCK protocol (https://wiki.qemu.org/Features/VirtioVsock). For example: nbd_connect_vsock (nbd, 2, 10809); There is no test of this feature because it only works between guest and host. You cannot start a server and client on the host and talk between them, which is what we'd need to write a sane test. --- configure.ac | 2 ++ fuse/nbdfuse.c | 26 +++++++++++++++++++ fuse/nbdfuse.pod | 8 ++++++ generator/generator | 51 ++++++++++++++++++++++++++++++++++++-- generator/states-connect.c | 22 ++++++++++++++++ lib/connect.c | 20 +++++++++++++++ lib/internal.h | 3 +++ 7 files changed, 130 insertions(+), 2 deletions(-) diff --git a/configure.ac b/configure.ac index a84580d..95ffca7 100644 --- a/configure.ac +++ b/configure.ac @@ -77,6 +77,8 @@ AC_CHECK_HEADERS([\ stdatomic.h \ sys/endian.h]) +AC_CHECK_HEADERS([linux/vm_sockets.h], [], [], [#include <sys/socket.h>]) + dnl Check for functions, all optional. AC_CHECK_FUNCS([\ execvpe]) diff --git a/fuse/nbdfuse.c b/fuse/nbdfuse.c index 75bb0be..c0aee79 100644 --- a/fuse/nbdfuse.c +++ b/fuse/nbdfuse.c @@ -24,6 +24,7 @@ #include <stdlib.h> #include <stdbool.h> #include <stdint.h> +#include <inttypes.h> #include <string.h> #include <getopt.h> #include <limits.h> @@ -97,6 +98,7 @@ usage (FILE *fp, int exitcode) " nbdfuse MOUNTPOINT[/FILENAME] --fd N\n" " nbdfuse MOUNTPOINT[/FILENAME] --tcp HOST PORT\n" " nbdfuse MOUNTPOINT[/FILENAME] --unix SOCKET\n" +" nbdfuse MOUNTPOINT[/FILENAME] --vsock CID PORT\n" "\n" "Please read the nbdfuse(1) manual page for full usage.\n" "\n" @@ -139,6 +141,7 @@ main (int argc, char *argv[]) MODE_SOCKET_ACTIVATION, MODE_TCP, MODE_UNIX, + MODE_VSOCK, } mode = MODE_URI; enum { HELP_OPTION = CHAR_MAX + 1, @@ -161,6 +164,7 @@ main (int argc, char *argv[]) { NULL } }; int c, fd, r; + uint32_t cid, port; int64_t ssize; const char *s; struct fuse_args fuse_args = FUSE_ARGS_INIT (0, NULL); @@ -262,6 +266,10 @@ main (int argc, char *argv[]) mode = MODE_UNIX; optind++; } + else if (strcmp (argv[optind], "--vsock") == 0) { + mode = MODE_VSOCK; + optind++; + } /* This is undocumented, but allow either URI or --uri URI. */ else if (strcmp (argv[optind], "--uri") == 0) { mode = MODE_URI; @@ -289,6 +297,7 @@ main (int argc, char *argv[]) usage (stderr, EXIT_FAILURE); break; case MODE_TCP: + case MODE_VSOCK: if (argc - optind != 2) usage (stderr, EXIT_FAILURE); break; @@ -357,6 +366,23 @@ main (int argc, char *argv[]) exit (EXIT_FAILURE); } break; + + case MODE_VSOCK: + if (sscanf (argv[optind], "%" SCNu32, &cid) != 1) { + fprintf (stderr, "%s: could not parse vsock cid: %s\n\n", + argv[0], argv[optind]); + exit (EXIT_FAILURE); + } + if (sscanf (argv[optind+1], "%" SCNu32, &port) != 1) { + fprintf (stderr, "%s: could not parse vsock port: %s\n\n", + argv[0], argv[optind]); + exit (EXIT_FAILURE); + } + if (nbd_connect_vsock (nbd, cid, port) == -1) { + fprintf (stderr, "%s\n", nbd_get_error ()); + exit (EXIT_FAILURE); + } + break; } ssize = nbd_get_size (nbd); diff --git a/fuse/nbdfuse.pod b/fuse/nbdfuse.pod index 3187822..3a7401c 100644 --- a/fuse/nbdfuse.pod +++ b/fuse/nbdfuse.pod @@ -19,6 +19,8 @@ Other modes: nbdfuse MOUNTPOINT[/FILENAME] --unix SOCKET + nbdfuse MOUNTPOINT[/FILENAME] --vsock CID PORT + =head1 DESCRIPTION nbdfuse presents a Network Block Device as a local file inside a FUSE @@ -230,6 +232,11 @@ unencrypted TCP socket. See also L<nbd_connect_tcp(3)>. Select Unix mode. Connect to an NBD server on a Unix domain socket. See also L<nbd_connect_unix(3)>. +=item B<--vsock> CID PORT + +Select vsock mode. Connect to an NBD server on a C<AF_VSOCK> socket. +See also L<nbd_connect_vsock(3)>. + =back =head1 NOTES @@ -294,6 +301,7 @@ L<nbd_connect_socket(3)>, L<nbd_connect_systemd_socket_activation(3)>, L<nbd_connect_tcp(3)>, L<nbd_connect_unix(3)>, +L<nbd_connect_vsock(3)>, L<libguestfs(3)>, L<guestfish(1)>, L<guestmount(1)>, diff --git a/generator/generator b/generator/generator index 54a8eb7..89dd52a 100755 --- a/generator/generator +++ b/generator/generator @@ -93,6 +93,7 @@ type external_event = | CmdCreate (* [nbd_create] function called *) | CmdConnectSockAddr (* [nbd_aio_connect] function called *) | CmdConnectUnix (* [nbd_aio_connect_unix] *) + | CmdConnectVSock (* [nbd_aio_connect_vsock] *) | CmdConnectTCP (* [nbd_aio_connect_tcp] *) | CmdConnectCommand (* [nbd_aio_connect_command] *) | CmdConnectSA (* [nbd_aio_connect_systemd_socket_activation]*) @@ -169,6 +170,7 @@ let rec state_machine = [ external_events = [ CmdCreate, ""; CmdConnectSockAddr, "CONNECT.START"; CmdConnectUnix, "CONNECT_UNIX.START"; + CmdConnectVSock, "CONNECT_VSOCK.START"; CmdConnectTCP, "CONNECT_TCP.START"; CmdConnectCommand, "CONNECT_COMMAND.START"; CmdConnectSA, "CONNECT_SA.START"; @@ -177,6 +179,7 @@ let rec state_machine = [ Group ("CONNECT", connect_state_machine); Group ("CONNECT_UNIX", connect_unix_state_machine); + Group ("CONNECT_VSOCK", connect_vsock_state_machine); Group ("CONNECT_TCP", connect_tcp_state_machine); Group ("CONNECT_COMMAND", connect_command_state_machine); Group ("CONNECT_SA", connect_sa_state_machine); @@ -236,6 +239,16 @@ and connect_unix_state_machine = [ }; ] +(* State machine implementing [nbd_aio_connect_vsock]. *) +and connect_vsock_state_machine = [ + State { + default_state with + name = "START"; + comment = "Connect to an AF_VSOCK socket"; + external_events = []; + }; +] + (* State machine implementing [nbd_aio_connect_tcp]. *) and connect_tcp_state_machine = [ State { @@ -1491,6 +1504,20 @@ when the connection has been made."; example = Some "examples/fetch-first-sector.c"; }; + "connect_vsock", { + default_call with + args = [ UInt32 "cid"; UInt32 "port" ]; ret = RErr; + permitted_states = [ Created ]; + shortdesc = "connect to NBD server over AF_VSOCK protocol"; + longdesc = "\ +Connect (synchronously) over the C<AF_VSOCK> protocol from a +virtual machine to an NBD server, usually running on the host. The +C<cid> and C<port> parameters specify the server address. Usually +C<cid> should be C<2> (to connect to the host), and C<port> might be +C<10809> or another port number assigned to you by the host +administrator. This call returns when the connection has been made."; + }; + "connect_tcp", { default_call with args = [ String "hostname"; String "port" ]; ret = RErr; @@ -2148,6 +2175,22 @@ on the connection."; example = Some "examples/aio-connect-read.c"; }; + "aio_connect_vsock", { + default_call with + args = [ UInt32 "cid"; UInt32 "port" ]; ret = RErr; + permitted_states = [ Created ]; + shortdesc = "connect to the NBD server over AF_VSOCK socket"; + longdesc = "\ +Begin connecting to the NBD server over the C<AF_VSOCK> +protocol to the server C<cid:port>. Parameters behave as documented in +L<nbd_connect_vsock(3)>. + +You can check if the connection is still connecting by calling +L<nbd_aio_is_connecting(3)>, or if it has connected to the server +and completed the NBD handshake by calling L<nbd_aio_is_ready(3)>, +on the connection."; + }; + "aio_connect_tcp", { default_call with args = [ String "hostname"; String "port" ]; ret = RErr; @@ -2793,6 +2836,8 @@ let first_version = [ "aio_connect_systemd_socket_activation", (1, 2); "connect_socket", (1, 2); "aio_connect_socket", (1, 2); + "connect_vsock", (1, 2); + "aio_connect_vsock", (1, 2); (* These calls are proposed for a future version of libnbd, but * have not been added to any released version so far. @@ -3151,7 +3196,7 @@ end = struct let all_external_events = [NotifyRead; NotifyWrite; CmdCreate; - CmdConnectSockAddr; CmdConnectUnix; CmdConnectTCP; + CmdConnectSockAddr; CmdConnectUnix; CmdConnectVSock; CmdConnectTCP; CmdConnectCommand; CmdConnectSA; CmdConnectSocket; CmdIssue] @@ -3161,6 +3206,7 @@ let string_of_external_event = function | CmdCreate -> "CmdCreate" | CmdConnectSockAddr -> "CmdConnectSockAddr" | CmdConnectUnix -> "CmdConnectUnix" + | CmdConnectVSock -> "CmdConnectVSock" | CmdConnectTCP -> "CmdConnectTCP" | CmdConnectCommand -> "CmdConnectCommand" | CmdConnectSA -> "CmdConnectSA" @@ -3173,6 +3219,7 @@ let c_string_of_external_event = function | CmdCreate -> "cmd_create" | CmdConnectSockAddr -> "cmd_connect_sockaddr" | CmdConnectUnix -> "cmd_connect_unix" + | CmdConnectVSock -> "cmd_connect_vsock" | CmdConnectTCP -> "cmd_connect_tcp" | CmdConnectCommand -> "cmd_connect_command" | CmdConnectSA -> "cmd_connect_sa" @@ -3624,7 +3671,7 @@ let generate_lib_states_run_c () = | NotifyWrite -> pr " r |= LIBNBD_AIO_DIRECTION_WRITE;\n" | CmdCreate | CmdConnectSockAddr - | CmdConnectUnix | CmdConnectTCP + | CmdConnectUnix | CmdConnectVSock | CmdConnectTCP | CmdConnectCommand | CmdConnectSA | CmdConnectSocket | CmdIssue -> () ) events; diff --git a/generator/states-connect.c b/generator/states-connect.c index d62b0f5..e4658a7 100644 --- a/generator/states-connect.c +++ b/generator/states-connect.c @@ -37,6 +37,10 @@ #include <sys/socket.h> #include <sys/un.h> +#ifdef HAVE_LINUX_VM_SOCKETS_H +#include <linux/vm_sockets.h> +#endif + /* Disable Nagle's algorithm on the socket, but don't fail. */ static void disable_nagle (int sock) @@ -118,6 +122,24 @@ STATE_MACHINE { SET_NEXT_STATE (%^CONNECT.START); return 0; + CONNECT_VSOCK.START: +#ifdef AF_VSOCK + struct sockaddr_vm svm = { + .svm_family = AF_VSOCK, + .svm_cid = h->svm_cid, + .svm_port = h->svm_port, + }; + const socklen_t len = sizeof svm; + + memcpy (&h->connaddr, &svm, len); + h->connaddrlen = len; + SET_NEXT_STATE (%^CONNECT.START); + return 0; +#else + set_error (ENOTSUP, "AF_VSOCK protocol is not supported"); + SET_NEXT_STATE (%.DEAD); +#endif + CONNECT_TCP.START: int r; diff --git a/lib/connect.c b/lib/connect.c index a0ef5f1..d8bb121 100644 --- a/lib/connect.c +++ b/lib/connect.c @@ -92,6 +92,16 @@ nbd_unlocked_connect_unix (struct nbd_handle *h, const char *unixsocket) return wait_until_connected (h); } +/* Connect to a vsock. */ +int +nbd_unlocked_connect_vsock (struct nbd_handle *h, uint32_t cid, uint32_t port) +{ + if (nbd_unlocked_aio_connect_vsock (h, cid, port) == -1) + return -1; + + return wait_until_connected (h); +} + /* Connect to a TCP port. */ int nbd_unlocked_connect_tcp (struct nbd_handle *h, @@ -388,6 +398,16 @@ nbd_unlocked_aio_connect_unix (struct nbd_handle *h, const char *unixsocket) return nbd_internal_run (h, cmd_connect_unix); } +int +nbd_unlocked_aio_connect_vsock (struct nbd_handle *h, + uint32_t cid, uint32_t port) +{ + h->svm_cid = cid; + h->svm_port = port; + + return nbd_internal_run (h, cmd_connect_vsock); +} + int nbd_unlocked_aio_connect_tcp (struct nbd_handle *h, const char *hostname, const char *port) diff --git a/lib/internal.h b/lib/internal.h index 6433183..ba053c2 100644 --- a/lib/internal.h +++ b/lib/internal.h @@ -197,6 +197,9 @@ struct nbd_handle { /* When connecting to Unix domain socket. */ char *unixsocket; + /* When connecting to a vsock. */ + uint32_t svm_cid, svm_port; + /* When connecting to TCP ports, these fields are used. */ char *hostname, *port; struct addrinfo hints; -- 2.23.0

On Fri, Oct 18, 2019 at 10:58:43AM -0500, Eric Blake wrote: I'm afraid I don't understand this. We could add it, but equally client code can just check AF_VSOCK the same way that libnbd does, ie with a configure test for the header and checking if AF_VSOCK is defined. You can actually test this just by running the following command on the host: $ ./run strace -f -o /tmp/log nbdsh -c 'h.connect_vsock(2, 10809)' The log shows how it fails: 3395572 socket(AF_VSOCK, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0) = 3 ... 3395572 connect(3, {sa_family=AF_VSOCK, sa_data="\0\09*\0\0\2\0\0\0\0\0\0\0"}, 16) = -1 ENODEV (No such device) That's unfortunate as it means we would have to connect to a non-existent socket and determine if it returns ENODEV or ECONNREFUSED (and if it returns something else - erm?!) Note that the socket(2) syscall doesn't fail because creating a server socket is perfectly valid whether in a host or guest context. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com libguestfs lets you edit virtual machines. Supports shell scripting, bindings from many languages. http://libguestfs.org