With new enough libnbd, we already support vsock by virtue of uri=; however, it's also nice to allow direct exposure of the nbd_connect_vsock() api. Signed-off-by: Eric Blake <eblake(a)redhat.com&gt; --- plugins/nbd/nbdkit-nbd-plugin.pod | 29 +++++++++++--- plugins/nbd/nbd.c | 63 ++++++++++++++++++++++++------- 2 files changed, 73 insertions(+), 19 deletions(-) diff --git a/plugins/nbd/nbdkit-nbd-plugin.pod b/plugins/nbd/nbdkit-nbd-plugin.pod index e4ac40d1..bd980209 100644 --- a/plugins/nbd/nbdkit-nbd-plugin.pod +++ b/plugins/nbd/nbdkit-nbd-plugin.pod @@ -6,6 +6,7 @@ nbdkit-nbd-plugin - proxy / forward to another NBD server nbdkit nbd { command=COMMAND [arg=ARG [...]] | hostname=HOST [port=PORT] | + vhost-cid=CID [port=PORT] | socket=SOCKNAME | socket-fd=FD | [uri=]URI } @@ -40,9 +41,9 @@ With L<qemu-nbd(8)>, read and write qcow2 files with nbdkit. =head1 PARAMETERS -One of B<socket>, B<hostname> (optionally with B<port>), B<uri>, -B<socket-fd> or B<command> must be given to specify which NBD server -to forward to: +One of B<socket>, B<hostname> (optionally with B<port>), B<vsock-cid> +(optionally with B<port>), B<uri>, B<socket-fd> or B<command> must be +given to specify which NBD server to forward to: =over 4 @@ -71,7 +72,22 @@ This option implies C<shared=true>. =item B<port=>PORT Connect to the NBD server at the remote C<HOST> using a TCP socket. -The optional port parameter overrides the default port (10809). +The optional port parameter overrides the default port (10809), and +may be a 16-bit number or a non-numeric string to look up the +well-known port for a service name. + +=item B<vhost-cid=>CID + +=item B<port=>PORT + +Connect to the NBD server at the given vsock C<CID> (for example, in a +guest VM, using the cid 2 will connect to a server in the host). The +optional port parameter overrides the default port (10809), and must +be a 32-bit number. This only works for platforms with the +C<AF_VSOCK> family of sockets and libnbd new enough to use it; +C<nbdkit --dump-plugin nbd> will contain C<libnbd_vsock=1> if this is +the case. For more details on AF_VSOCK, see +L<nbdkit-service(1)/AF_VSOCK>. =item B<socket=>SOCKNAME @@ -87,8 +103,9 @@ option implies C<shared=true>. When C<uri> is supplied, decode C<URI> to determine the address to connect to. A URI can specify a TCP connection (such as -C<nbd://localhost:10809/export>) or a Unix socket (such as -C<nbd+unix:///export?socket=/path/to/sock>). Remember you may need to +C<nbd://localhost:10809/export>), a Unix socket (such as +C<nbd+unix:///export?socket=/path/to/sock>), or a vsock connection +(such as C<nbd+vsock:///2:10809/export>). Remember you may need to quote the parameter to protect it from the shell. The C<uri> parameter is only available when the plugin was compiled diff --git a/plugins/nbd/nbd.c b/plugins/nbd/nbd.c index e446d52b..3f84375b 100644 --- a/plugins/nbd/nbd.c +++ b/plugins/nbd/nbd.c @@ -46,6 +46,7 @@ #include <semaphore.h> #include <poll.h> #include <fcntl.h> +#include <sys/socket.h> #include <libnbd.h> @@ -61,6 +62,12 @@ DEFINE_VECTOR_TYPE(string_vector, const char *); +#if !defined AF_VSOCK || !LIBNBD_HAVE_NBD_CONNECT_VSOCK +#define USE_VSOCK 0 +#else +#define USE_VSOCK 1 +#endif + /* The per-transaction details */ struct transaction { int64_t cookie; @@ -87,8 +94,15 @@ static char *sockname; /* Connect to server via TCP socket */ static const char *hostname; + +/* Valid with TCP or VSOCK */ static const char *port; +/* Connect to server via AF_VSOCK socket */ +static const char *raw_cid; +static uint32_t cid; +static uint32_t vport; + /* Connect to a command. */ static string_vector command = empty_vector; @@ -126,11 +140,8 @@ nbdplug_unload (void) free (command.ptr); /* the strings are statically allocated */ } -/* Called for each key=value passed on the command line. This plugin - * accepts socket=<sockname>, hostname=<hostname>/port=<port>, or - * [uri=]<uri> (exactly one connection required), and optional - * parameters export=<name>, retry=<n>, shared=<bool> and various - * tls settings. +/* Called for each key=value passed on the command line. See + * nbdplug_config_help for the various keys recognized. */ static int nbdplug_config (const char *key, const char *value) @@ -148,6 +159,10 @@ nbdplug_config (const char *key, const char *value) hostname = value; else if (strcmp (key, "port") == 0) port = value; + else if (strcmp (key, "vsock_cid") == 0 || + strcmp (key, "vsock-cid") == 0 || + strcmp (key, "cid") == 0) + raw_cid = value; else if (strcmp (key, "uri") == 0) uri = value; else if (strcmp (key, "command") == 0 || strcmp (key, "arg") == 0) { @@ -220,23 +235,25 @@ static int nbdplug_config_complete (void) { int c = !!sockname + !!hostname + !!uri + - (command.size > 0) + (socket_fd >= 0); + (command.size > 0) + (socket_fd >= 0) + !!raw_cid; /* Check the user passed exactly one connection parameter. */ if (c > 1) { nbdkit_error ("cannot mix Unix ‘socket’, TCP ‘hostname’/‘port’, " - "‘command’, ‘socket-fd’ and ‘uri’ parameters"); + "‘vhost-cid’, ‘command’, ‘socket-fd’ and ‘uri’ parameters"); return -1; } if (c == 0) { - nbdkit_error ("exactly one of ‘socket’, ‘hostname’, ‘command’, ‘socket-fd’ " - "and ‘uri’ parameters must be specified"); + nbdkit_error ("exactly one of ‘socket’, ‘hostname’, ‘vhost-cid’, " + "‘command’, ‘socket-fd’ and ‘uri’ parameters must be " + "specified"); return -1; } - /* Port, if present, should only be used with hostname. */ - if (port && !hostname) { - nbdkit_error ("‘port’ parameter should only be used with ‘hostname’"); + /* Port, if present, should only be used with hostname or vsock-cid. */ + if (port && !(hostname || raw_cid)) { + nbdkit_error ("‘port’ parameter should only be used with ‘hostname’ or " + "‘vsock-cid’"); return -1; } @@ -266,6 +283,18 @@ nbdplug_config_complete (void) if (!port) port = "10809"; } + else if (raw_cid) { +#if !USE_VSOCK + nbdkit_error ("libnbd was compiled without vsock support"); + return -1; +#else + if (!port) + port = "10809"; + if (nbdkit_parse_uint32_t ("vsock_cid", raw_cid, &cid) == -1 || + nbdkit_parse_uint32_t ("port", port, &vport) == -1) + return -1; +#endif + } else if (command.size > 0) { /* Add NULL sentinel to the command. */ if (string_vector_append (&command, NULL) == -1) { @@ -320,7 +349,8 @@ nbdplug_after_fork (void) "[uri=]<URI> URI of an NBD socket to connect to (if supported).\n" \ "socket=<SOCKNAME> The Unix socket to connect to.\n" \ "hostname=<HOST> The hostname for the TCP socket to connect to.\n" \ - "port=<PORT> TCP port or service name to use (default 10809).\n" \ + "port=<PORT> TCP/VHOST port or service name to use (default 10809).\n" \ + "vhost_cid=<CID> The cid for the VSOCK socket to connect to.\n" \ "command=<COMMAND> Command to run.\n" \ "arg=<ARG> Parameters for command.\n" \ "socket-fd=<FD> Socket file descriptor to connect to.\n" \ @@ -346,6 +376,7 @@ nbdplug_dump_plugin (void) printf ("libnbd_version=%s\n", nbd_get_version (nbd)); printf ("libnbd_tls=%d\n", nbd_supports_tls (nbd)); printf ("libnbd_uri=%d\n", nbd_supports_uri (nbd)); + printf ("libnbd_vsock=%d\n", USE_VSOCK); nbd_close (nbd); } @@ -545,6 +576,12 @@ nbdplug_open_handle (int readonly) r = nbd_connect_unix (h->nbd, sockname); else if (hostname) r = nbd_connect_tcp (h->nbd, hostname, port); + else if (raw_cid) +#if !USE_VSOCK + abort (); +#else + r = nbd_connect_vsock (h->nbd, cid, vport); +#endif else if (command.size > 0) r = nbd_connect_systemd_socket_activation (h->nbd, (char **) command.ptr); else if (socket_fd >= 0)