search for: nbd_can_meta_context

Rich recently patched things to generate one man page per function rather than libnbd-api.3 (nice), but in doing so got stumped by a problem with a fresh git clone (automake fails for any 'include' directive that does not already exist). I've figured out how to hack around it, but the hack requires GNU make. We already use GNU make constructs elsewhere (such as $(wildcard)), but

...whether blocks of data are allocated, zero or sparse). + +This command returns how many meta contexts have been added to +the list to request from the server via L<nbd_add_meta_context(3)>. +The server is not obligated to honor all of the requests; to see +what it actually supports, see L<nbd_can_meta_context(3)>."; + see_also = [Link "block_status"; Link "can_meta_context"; + Link "add_meta_context"; Link "get_meta_context"; + Link "clear_meta_contexts"]; + }; + + "get_meta_context", { + default_ca...

...ollowup to your patch, to add more documentation about the constants, and to use them in our testsuite: diff --git i/generator/generator w/generator/generator index 9d8d257..1cfcb3d 100755 --- i/generator/generator +++ w/generator/generator @@ -1118,7 +1118,10 @@ was actually negotiated, call C<nbd_can_meta_context> after connecting. The single parameter is the name of the metadata context, -for example C<\"base:allocation\">. +for example C<LIBNBD_CONTEXT_BASE_ALLOCATION>. +B<E<lt>libnbd.hE<gt>> includes defined constants beginning with +C<LIBNBD_CONTEXT_>...

...69,7 @@ main (int argc, char *argv[]) fprintf (fp, "%" PRIi64 "\n", size); } else if (map) { /* --map (!list_all) */ - uint64_t offset, prev_offset; + uint64_t offset, prev_offset, align, max_len; /* Did we get the requested map? */ if (!nbd_can_meta_context (nbd, map)) { @@ -276,6 +278,8 @@ main (int argc, char *argv[]) progname, map); exit (EXIT_FAILURE); } + align = nbd_get_block_size (nbd, LIBNBD_SIZE_MINIMUM) ?: 512; + max_len = UINT32_MAX - align + 1; size = nbd_get_size (nbd); if (size == -1) { @@ -28...

...server to fail the negotiation request."; see_also = ["L<nbd_get_request_structured_replies(3)>"; "L<nbd_set_handshake_flags(3)>"; + "L<nbd_get_structured_replies_negotiated(3)>"; "L<nbd_can_meta_context(3)>"; "L<nbd_can_df(3)>"]; }; @@ -1322,10 +1323,26 @@ request."; shortdesc = "see if structured replies are attempted"; longdesc = "\ Return the state of the request structured replies flag on this -handle. Note that this only reports whet...

...Either of the following extension tests will prove that a newstyle server is present (unfortunately, this does not help for a newstyle server that does not support either extension): - If nbd_can_df(h) returns true. - If the client requests nbd_add_meta_context(h, context) prior to connection, then nbd_can_meta_context(h, context) returns true; the most commonly supported context is LIBNBD_CONTEXT_BASE_ALLOCATION. Test if libnbd is vulnerable ---------------------------- Run the following command (tested with nbdkit 1.12 or newer): $ nbdsh -c 'h.set_tls(nbd.TLS_REQUIRE)' \ -c 'h.connect_command([...

...tatus call), this did not warrant a CVE. However, since it is a case where a server's reply can prompt a libnbd denial of service crash, I will be sending a security announcement and upcoming patch be to the libnbd-security man page once backports are in place. Fixes: 55b09667 ("api: Fix nbd_can_meta_context if NBD_OPT_SET_META_CONTEXT fails", v1.15.3) Signed-off-by: Eric Blake <eblake at redhat.com> --- generator/states-reply-chunk.c | 1 + 1 file changed, 1 insertion(+) diff --git a/generator/states-reply-chunk.c b/generator/states-reply-chunk.c index 02c65414..26b8a6b0 100644 --- a/gene...

This just defines the namespace, its contexts and related constants and the only supported one is currently base:allocation. The names of the constants are not very future-proof, but shorter than LIBNBD_META_NS_CONTEXT_BASE_ALLOCATION or similar. Currently the output looks like this: /* "base" namespace */ /* "base" namespace contexts */ /* "base:allocation"

...]; ret = RErr; + permitted_states = [ Created ]; + first_version = (1, 2); + shortdesc = "control use of structured replies"; + longdesc = "\ +By default, libnbd tries to negotiate structured replies with the +server, as this protocol extension must be in use before +C<nbd_can_meta_context> or C<nbd_can_df> can return true. However, +for integration testing, it can be useful to clear this flag +rather than find a way to alter the server to fail the negotiation +request."; + see_also = ["L<nbd_get_request_structured_replies(3)>"; + &quo...

...dle; - int i = nbd_read_only (h->nbd); + int i = nbd_is_read_only (h->nbd); if (i == -1) { nbdkit_error ("failure to check readonly flag: %s", nbd_get_error ()); @@ -674,7 +676,7 @@ static int nbdplug_can_extents (void *handle) { struct handle *h = handle; - int i = nbd_can_meta_context (h->nbd, "base:allocation"); + int i = nbd_can_meta_context (h->nbd, LIBNBD_CONTEXT_BASE_ALLOCATION); if (i == -1) { nbdkit_error ("failure to check extents ability: %s", nbd_get_error ()); @@ -693,8 +695,8 @@ nbdplug_pread (void *handle, void *buf, uint32_t coun...

...eta_context(3)> +at other times in the negotiation sequence; and even when using +just L<nbd_opt_info(3)>, it can be faster to collect the server's results by relying on the callback function passed to L<nbd_opt_list_meta_context(3)> than a series of post-process calls to L<nbd_can_meta_context(3)>. Note that this control has no effect if the server does not -negotiate structured replies, or if the client did not request -any contexts via L<nbd_add_meta_context(3)>. Setting this -control to false may cause L<nbd_block_status(3)> to fail."; +negotiate structured repl...

This replaces 13/13 of my v2 series; and now that it has pretty good testsuite coverage and demonstrable performance improvement to nbdinfo, I'm going ahead and pushing this now. We may still want to add further nbd_opt_* commands for other fine-grained tuning of negotiation, but for now, I think things have stabilized on this end, and I can return to polishing .list_exports on the nbdkit

--- generator/API.ml | 2 +- lib/handle.c | 4 ++-- 2 files changed, 3 insertions(+), 3 deletions(-) diff --git a/generator/API.ml b/generator/API.ml index 770f41e..fd6f033 100644 --- a/generator/API.ml +++ b/generator/API.ml @@ -1024,7 +1024,7 @@ what it actually supports, see L<nbd_can_meta_context(3)>."; "get_meta_context", { default_call with - args = [ Int "i" ]; ret = RString; + args = [ SizeT "i" ]; ret = RString; shortdesc = "return the i'th meta context request"; longdesc = "\ During connection libnbd c...

I'm posting this now, as I'm at the end of a workday and I got things working for manual experimentation. Still to do: - write interop tests for qemu-nbd and nbdkit (including my proposed patch addition of qemu-nbd -A to show qemu:allocation-depth) - figure out if we can make 'nbdinfo --map' use the new API to automatically select all contexts advertised by the server Eric Blake

...d_set_tls_psk_file \ - nbd_add_meta_context \ - nbd_connect_uri \ - nbd_connect_unix \ - nbd_connect_tcp \ - nbd_connect_command \ - nbd_is_read_only \ - nbd_can_flush \ - nbd_can_fua \ - nbd_is_rotational \ - nbd_can_trim \ - nbd_can_zero \ - nbd_can_df \ - nbd_can_multi_conn \ - nbd_can_cache \ - nbd_can_meta_context \ - nbd_get_size \ - nbd_pread \ - nbd_pread_structured \ - nbd_pwrite \ - nbd_shutdown \ - nbd_flush \ - nbd_trim \ - nbd_cache \ - nbd_zero \ - nbd_block_status \ - nbd_poll \ - nbd_aio_connect \ - nbd_aio_connect_uri \ - nbd_aio_connect_unix \ - nbd_aio_connect_tcp \ - nbd_aio_connect_command \...

...esting, it can be useful to clear this flag rather than find a way to alter the server to fail the negotiation request."; see_also = ["L<nbd_get_request_structured_replies(3)>"; + "L<nbd_set_handshake_flags(3)>"; "L<nbd_can_meta_context(3)>"; "L<nbd_can_df(3)>"]; }; @@ -1277,6 +1285,66 @@ able to honor that request"; see_also = ["L<nbd_set_request_structured_replies(3)>"]; }; + "set_handshake_flags", { + default_call with + args = [ Flags ("flags"...

...d_set_tls_psk_file \ + nbd_add_meta_context \ + nbd_connect_uri \ + nbd_connect_unix \ + nbd_connect_tcp \ + nbd_connect_command \ + nbd_is_read_only \ + nbd_can_flush \ + nbd_can_fua \ + nbd_is_rotational \ + nbd_can_trim \ + nbd_can_zero \ + nbd_can_df \ + nbd_can_multi_conn \ + nbd_can_cache \ + nbd_can_meta_context \ + nbd_get_size \ + nbd_pread \ + nbd_pread_structured \ + nbd_pwrite \ + nbd_shutdown \ + nbd_flush \ + nbd_trim \ + nbd_cache \ + nbd_zero \ + nbd_block_status \ + nbd_poll \ + nbd_aio_connect \ + nbd_aio_connect_uri \ + nbd_aio_connect_unix \ + nbd_aio_connect_tcp \ + nbd_aio_connect_command \...

...ap.c | 65 +++++++++++++++++++++++------ 3 files changed, 86 insertions(+), 41 deletions(-) diff --git a/generator/generator b/generator/generator index 91545ce..1261d54 100755 --- a/generator/generator +++ b/generator/generator @@ -1414,7 +1414,10 @@ supported by the server (see C<nbd_can_meta_context>) this call returns information about extents by calling back to the extent function. The callback cannot call C<nbd_*> APIs on the same handle since it holds the handle lock and will -cause a deadlock. +cause a deadlock. If the callback returns C<-1>, any remaining +contexts wi...

...warrant a CVE. However, since it is a case where a > server's reply can prompt a libnbd denial of service crash, I will be > sending a security announcement and upcoming patch be to the > libnbd-security man page once backports are in place. > > Fixes: 55b09667 ("api: Fix nbd_can_meta_context if NBD_OPT_SET_META_CONTEXT fails", v1.15.3) > Signed-off-by: Eric Blake <eblake at redhat.com> > --- > generator/states-reply-chunk.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/generator/states-reply-chunk.c b/generator/states-reply-chunk.c > index 0...

This is a rough-and-ready implementation of nbdinfo --map option, to display the allocation and other metadata of NBD exports. I only tested it lightly against nbdkit. It needs at least some tests. Command like these should work: nbdinfo --map nbd://localhost nbdinfo --map=qemu:dirty-bitmap nbd://localhost Rich.