Security

Two security problems were found during development of libnbd 1.2. Both were backported to the 1.0 stable branch. Upgrading is highly advisable.

CVE-2019-14842 protocol downgrade attack when using "LIBNBD_TLS_REQUIRE"

See the full announcement and links to mitigation, tests and fixes here: https://www.redhat.com/archives/libguestfs/2019-September/msg00128.html

remote code execution vulnerability

See the full announcement here: https://www.redhat.com/archives/libguestfs/2019-October/msg00060.html

New APIs

nbd_can_fast_zero(3)

Test support by the server for fast zeroing (Eric Blake).

nbd_connect_socket(3)

nbd_aio_connect_socket(3)

Connect to a local connected socket which you create in your main program using your own chosen method.

nbd_connect_systemd_socket_activation(3)

nbd_aio_connect_systemd_socket_activation(3)

Connect to local processes that support systemd socket activation.

nbd_connect_vsock(3)

nbd_aio_connect_vsock(3)

Used to connect to servers over "AF_VSOCK".

nbd_get_handshake_flags(3)

nbd_set_handshake_flags(3)

nbd_get_request_structured_replies(3)

nbd_set_request_structured_replies(3)

nbd_get_structured_replies_negotiated(3)

Can be used when testing NBD servers to avoid various NBD features (Eric Blake).

nbd_get_protocol(3)

Get the NBD protocol variant that the server supports.

nbd_get_tls_negotiated(3)

Did we actually negotiate a TLS connection?

nbd_set_uri_allow_local_file(3)

nbd_set_uri_allow_tls(3)

nbd_set_uri_allow_transports(3)

These can be used to filter NBD URIs before calling nbd_connect_uri(3).

New features

New tool nbdfuse(1) lets you create a loop-mounted file backed by an NBD server without needing root.

"AF_VSOCK" is now a supported protocol (thanks Stefan Hajnoczi and Stefano Garzarella).

Support for the "FAST_ZERO" flag (Eric Blake).

Allow disabling certain protocol features, to make it easier to test servers (Eric Blake).

Stack-allocated Variable Length Arrays (VLAs) are now banned throughout the library, making the library easier to consume from threads and other small stack situations.

Reproducible builds (Chris Lamb).

Support for filtering potentially dangerous or undesirable NBD URI features.

Documentation

Many improvements to the generated manual pages, including:

• Separate "RETURN VALUE" and "ERRORS" sections for each API function.
• Example code.
• Relevant links can be added to the "SEE ALSO" section.
• Link to NBD URI specification where relevant, and improve documentation around what URIs libnbd supports.
• Document libnbd version number scheme.
• Document limits on export name length, encoding etc.

New libnbd-security(3) man page listing past security issues and remediations (Eric Blake).

Tools

nbdsh(1) has a new --base-allocation option which can be used to request "base:allocation" metadata context.

New nbdsh(1) --uri (-u) option to connect to URIs.

Tests

You can now fuzz libnbd using either American Fuzzy Lop or clang’s libFuzzer.

Add unit tests for nbdsh(1) (Eric Blake).

Improved interop testing with various NBD servers and features.

Other improvements and bug fixes

nbd_connect_tcp(3) now tries to return the correct errno(3) from the underlying connect(2) call when that fails.

The nbd-protocol.h header file is now shared between libnbd and nbdkit.

Better fork-safety in "nbd_connect_*" APIs.

The code was analyzed with Coverity and various problems identified and fixed.