From 7d72cea18905a4b635ac75997d5ce719ebc5ffb3 Mon Sep 17 00:00:00 2001 From: John Snow Date: Wed, 27 Mar 2019 17:22:53 +0100 Subject: [PATCH 115/163] qemu-nbd: Add --list option RH-Author: John Snow Message-id: <20190327172308.31077-41-jsnow@redhat.com> Patchwork-id: 85204 O-Subject: [RHEL-7.7 qemu-kvm-rhev PATCH 40/55] qemu-nbd: Add --list option Bugzilla: 1691009 RH-Acked-by: Stefan Hajnoczi RH-Acked-by: Max Reitz RH-Acked-by: Miroslav Rezanina From: Eric Blake We want to be able to detect whether a given qemu NBD server is exposing the right export(s) and dirty bitmaps, at least for regression testing. We could use 'nbd-client -l' from the upstream NBD project to list exports, but it's annoying to rely on out-of-tree binaries; furthermore, nbd-client doesn't necessarily know about all of the qemu NBD extensions. Thus, it is time to add a new mode to qemu-nbd that merely sniffs all possible information from the server during handshake phase, then disconnects and dumps the information. This patch actually implements --list/-L, while reusing other options such as --tls-creds for now designating how to connect as the client (rather than their non-list usage of how to operate as the server). I debated about adding this functionality to something akin to 'qemu-img info' - but that tool does not readily lend itself to connecting to an arbitrary NBD server without also tying to a specific export (I may, however, still add ImageInfoSpecificNBD for reporting the bitmaps available when connecting to a single export). And, while it may feel a bit odd that normally qemu-nbd is a server but 'qemu-nbd -L' is a client, we are not really making the qemu-nbd binary that much larger, because 'qemu-nbd -c' has to operate as both server and client simultaneously across two threads when feeding the kernel module for /dev/nbdN access. Sample output: $ qemu-nbd -L exports available: 1 export: '' size: 65536 flags: 0x4ed ( flush fua trim zeroes df cache ) min block: 512 opt block: 4096 max block: 33554432 available meta contexts: 1 base:allocation Note that the output only lists sizes if the server sent NBD_FLAG_HAS_FLAGS, because a newstyle server does not give the size otherwise. It has the side effect that for really old servers that did not send any flags, the size is not output even though it was available. However, I'm not too concerned about that - oldstyle servers are (rightfully) getting less common to encounter (qemu 3.0 was the last version where we even serve it), and most existing servers that still even offer oldstyle negotiation (such as nbdkit) still send flags (since that was added to the NBD protocol in 2007 to permit read-only connections). Not done here, but maybe worth future experiments: capture the meat of NBDExportInfo into a QAPI struct, and use the generated QAPI pretty-printers instead of hand-rolling our output loop. It would also permit us to add a JSON output mode for machine parsing. Signed-off-by: Eric Blake Reviewed-by: Richard W.M. Jones Message-Id: <20190117193658.16413-20-eblake@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy (cherry picked from commit 68b96f15838d309ef791cb83b5eec1bd7da271c2) Signed-off-by: John Snow Signed-off-by: Miroslav Rezanina --- qemu-nbd.c | 155 +++++++++++++++++++++++++++++++++++++++++++++++++++++----- qemu-nbd.texi | 29 +++++++++-- 2 files changed, 167 insertions(+), 17 deletions(-) diff --git a/qemu-nbd.c b/qemu-nbd.c index 3c53870..1f7b2a0 100644 --- a/qemu-nbd.c +++ b/qemu-nbd.c @@ -76,7 +76,8 @@ static void usage(const char *name) { (printf) ( "Usage: %s [OPTIONS] FILE\n" -"QEMU Disk Network Block Device Server\n" +" or: %s -L [OPTIONS]\n" +"QEMU Disk Network Block Device Utility\n" "\n" " -h, --help display this help and exit\n" " -V, --version output version information and exit\n" @@ -98,6 +99,7 @@ static void usage(const char *name) " -B, --bitmap=NAME expose a persistent dirty bitmap\n" "\n" "General purpose options:\n" +" -L, --list list exports available from another NBD server\n" " --object type,id=ID,... define an object such as 'secret' for providing\n" " passwords and/or encryption keys\n" " --tls-creds=ID use id of an earlier --object to provide TLS\n" @@ -131,7 +133,7 @@ static void usage(const char *name) " --image-opts treat FILE as a full set of image options\n" "\n" QEMU_HELP_BOTTOM "\n" - , name, NBD_DEFAULT_PORT, "DEVICE"); + , name, name, NBD_DEFAULT_PORT, "DEVICE"); } static void version(const char *name) @@ -243,6 +245,91 @@ static void termsig_handler(int signum) } +static int qemu_nbd_client_list(SocketAddress *saddr, QCryptoTLSCreds *tls, + const char *hostname) +{ + int ret = EXIT_FAILURE; + int rc; + Error *err = NULL; + QIOChannelSocket *sioc; + NBDExportInfo *list; + int i, j; + + sioc = qio_channel_socket_new(); + if (qio_channel_socket_connect_sync(sioc, saddr, &err) < 0) { + error_report_err(err); + return EXIT_FAILURE; + } + rc = nbd_receive_export_list(QIO_CHANNEL(sioc), tls, hostname, &list, + &err); + if (rc < 0) { + if (err) { + error_report_err(err); + } + goto out; + } + printf("exports available: %d\n", rc); + for (i = 0; i < rc; i++) { + printf(" export: '%s'\n", list[i].name); + if (list[i].description && *list[i].description) { + printf(" description: %s\n", list[i].description); + } + if (list[i].flags & NBD_FLAG_HAS_FLAGS) { + printf(" size: %" PRIu64 "\n", list[i].size); + printf(" flags: 0x%x (", list[i].flags); + if (list[i].flags & NBD_FLAG_READ_ONLY) { + printf(" readonly"); + } + if (list[i].flags & NBD_FLAG_SEND_FLUSH) { + printf(" flush"); + } + if (list[i].flags & NBD_FLAG_SEND_FUA) { + printf(" fua"); + } + if (list[i].flags & NBD_FLAG_ROTATIONAL) { + printf(" rotational"); + } + if (list[i].flags & NBD_FLAG_SEND_TRIM) { + printf(" trim"); + } + if (list[i].flags & NBD_FLAG_SEND_WRITE_ZEROES) { + printf(" zeroes"); + } + if (list[i].flags & NBD_FLAG_SEND_DF) { + printf(" df"); + } + if (list[i].flags & NBD_FLAG_CAN_MULTI_CONN) { + printf(" multi"); + } + if (list[i].flags & NBD_FLAG_SEND_RESIZE) { + printf(" resize"); + } + if (list[i].flags & NBD_FLAG_SEND_CACHE) { + printf(" cache"); + } + printf(" )\n"); + } + if (list[i].min_block) { + printf(" min block: %u\n", list[i].min_block); + printf(" opt block: %u\n", list[i].opt_block); + printf(" max block: %u\n", list[i].max_block); + } + if (list[i].n_contexts) { + printf(" available meta contexts: %d\n", list[i].n_contexts); + for (j = 0; j < list[i].n_contexts; j++) { + printf(" %s\n", list[i].contexts[j]); + } + } + } + nbd_free_export_list(list, rc); + + ret = EXIT_SUCCESS; + out: + object_unref(OBJECT(sioc)); + return ret; +} + + #if HAVE_NBD_DEVICE static void *show_parts(void *arg) { @@ -425,7 +512,8 @@ static QemuOptsList qemu_object_opts = { -static QCryptoTLSCreds *nbd_get_tls_creds(const char *id, Error **errp) +static QCryptoTLSCreds *nbd_get_tls_creds(const char *id, bool list, + Error **errp) { Object *obj; QCryptoTLSCreds *creds; @@ -445,10 +533,18 @@ static QCryptoTLSCreds *nbd_get_tls_creds(const char *id, Error **errp) return NULL; } - if (creds->endpoint != QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) { - error_setg(errp, - "Expecting TLS credentials with a server endpoint"); - return NULL; + if (list) { + if (creds->endpoint != QCRYPTO_TLS_CREDS_ENDPOINT_CLIENT) { + error_setg(errp, + "Expecting TLS credentials with a client endpoint"); + return NULL; + } + } else { + if (creds->endpoint != QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) { + error_setg(errp, + "Expecting TLS credentials with a server endpoint"); + return NULL; + } } object_ref(obj); return creds; @@ -471,7 +567,8 @@ static void setup_address_and_port(const char **address, const char **port) static const char *socket_activation_validate_opts(const char *device, const char *sockpath, const char *address, - const char *port) + const char *port, + bool list) { if (device != NULL) { return "NBD device can't be set when using socket activation"; @@ -489,6 +586,10 @@ static const char *socket_activation_validate_opts(const char *device, return "TCP port number can't be set when using socket activation"; } + if (list) { + return "List mode is incompatible with socket activation"; + } + return NULL; } @@ -512,7 +613,7 @@ int main(int argc, char **argv) int64_t fd_size; QemuOpts *sn_opts = NULL; const char *sn_id_or_name = NULL; - const char *sopt = "hVb:o:p:rsnP:c:dvk:e:f:tl:x:T:D:B:"; + const char *sopt = "hVb:o:p:rsnP:c:dvk:e:f:tl:x:T:D:B:L"; struct option lopt[] = { { "help", no_argument, NULL, 'h' }, { "version", no_argument, NULL, 'V' }, @@ -525,6 +626,7 @@ int main(int argc, char **argv) { "bitmap", required_argument, NULL, 'B' }, { "connect", required_argument, NULL, 'c' }, { "disconnect", no_argument, NULL, 'd' }, + { "list", no_argument, NULL, 'L' }, { "snapshot", no_argument, NULL, 's' }, { "load-snapshot", required_argument, NULL, 'l' }, { "nocache", no_argument, NULL, 'n' }, @@ -559,7 +661,7 @@ int main(int argc, char **argv) Error *local_err = NULL; BlockdevDetectZeroesOptions detect_zeroes = BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF; QDict *options = NULL; - const char *export_name = ""; /* Default export name */ + const char *export_name = NULL; /* defaults to "" later for server mode */ const char *export_description = NULL; const char *bitmap = NULL; const char *tlscredsid = NULL; @@ -567,6 +669,7 @@ int main(int argc, char **argv) bool writethrough = true; char *trace_file = NULL; bool fork_process = false; + bool list = false; int old_stderr = -1; unsigned socket_activation; @@ -760,13 +863,33 @@ int main(int argc, char **argv) case QEMU_NBD_OPT_FORK: fork_process = true; break; + case 'L': + list = true; + break; } } - if ((argc - optind) != 1) { + if (list) { + if (argc != optind) { + error_report("List mode is incompatible with a file name"); + exit(EXIT_FAILURE); + } + if (export_name || export_description || dev_offset || partition || + device || disconnect || fmt || sn_id_or_name || bitmap || + seen_aio || seen_discard || seen_cache) { + error_report("List mode is incompatible with per-device settings"); + exit(EXIT_FAILURE); + } + if (fork_process) { + error_report("List mode is incompatible with forking"); + exit(EXIT_FAILURE); + } + } else if ((argc - optind) != 1) { error_report("Invalid number of arguments"); error_printf("Try `%s --help' for more information.\n", argv[0]); exit(EXIT_FAILURE); + } else if (!export_name) { + export_name = ""; } qemu_opts_foreach(&qemu_object_opts, @@ -785,7 +908,8 @@ int main(int argc, char **argv) } else { /* Using socket activation - check user didn't use -p etc. */ const char *err_msg = socket_activation_validate_opts(device, sockpath, - bindto, port); + bindto, port, + list); if (err_msg != NULL) { error_report("%s", err_msg); exit(EXIT_FAILURE); @@ -808,7 +932,7 @@ int main(int argc, char **argv) error_report("TLS is not supported with a host device"); exit(EXIT_FAILURE); } - tlscreds = nbd_get_tls_creds(tlscredsid, &local_err); + tlscreds = nbd_get_tls_creds(tlscredsid, list, &local_err); if (local_err) { error_report("Failed to get TLS creds %s", error_get_pretty(local_err)); @@ -816,6 +940,11 @@ int main(int argc, char **argv) } } + if (list) { + saddr = nbd_build_socket_address(sockpath, bindto, port); + return qemu_nbd_client_list(saddr, tlscreds, bindto); + } + #if !HAVE_NBD_DEVICE if (disconnect || device) { error_report("Kernel /dev/nbdN support not available"); diff --git a/qemu-nbd.texi b/qemu-nbd.texi index f218291..386bece 100644 --- a/qemu-nbd.texi +++ b/qemu-nbd.texi @@ -2,6 +2,8 @@ @c man begin SYNOPSIS @command{qemu-nbd} [OPTION]... @var{filename} +@command{qemu-nbd} @option{-L} [OPTION]... + @command{qemu-nbd} @option{-d} @var{dev} @c man end @end example @@ -14,6 +16,8 @@ Other uses: @itemize @item Bind a /dev/nbdX block device to a QEMU server (on Linux). +@item +As a client to query exports of a remote NBD server. @end itemize @c man end @@ -31,13 +35,15 @@ See the @code{qemu(1)} manual page for full details of the properties supported. The common object types that it makes sense to define are the @code{secret} object, which is used to supply passwords and/or encryption keys, and the @code{tls-creds} object, which is used to supply TLS -credentials for the qemu-nbd server. +credentials for the qemu-nbd server or client. @item -p, --port=@var{port} -The TCP port to listen on (default @samp{10809}). +The TCP port to listen on as a server, or connect to as a client +(default @samp{10809}). @item -o, --offset=@var{offset} The offset into the image. @item -b, --bind=@var{iface} -The interface to bind to (default @samp{0.0.0.0}). +The interface to bind to as a server, or connect to as a client +(default @samp{0.0.0.0}). @item -k, --socket=@var{path} Use a unix socket with path @var{path}. @item --image-opts @@ -97,10 +103,16 @@ Set the NBD volume export name (default of a zero-length string). @item -D, --description=@var{description} Set the NBD volume export description, as a human-readable string. +@item -L, --list +Connect as a client and list all details about the exports exposed by +a remote NBD server. This enables list mode, and is incompatible +with options that change behavior related to a specific export (such as +@option{--export-name}, @option{--offset}, ...). @item --tls-creds=ID Enable mandatory TLS encryption for the server by setting the ID of the TLS credentials object previously created with the --object -option. +option; or provide the credentials needed for connecting as a client +in list mode. @item --fork Fork off the server process and exit the parent once the server is running. @item -v, --verbose @@ -162,6 +174,15 @@ qemu-nbd -c /dev/nbd0 -f qcow2 file.qcow2 qemu-nbd -d /dev/nbd0 @end example +Query a remote server to see details about what export(s) it is +serving on port 10809, and authenticating via PSK: + +@example +qemu-nbd \ + --object tls-creds-psk,id=tls0,dir=/tmp/keys,username=eblake,endpoint=client \ + --tls-creds tls0 -L -b remote.example.com +@end example + @c man end @ignore -- 1.8.3.1