The 'name' option for NBD exports is optional. Add a note that the
default for the option is the node name (people could otherwise expect
that it's the empty string like for qemu-nbd).
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20210305094856.18964-1-kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
World-writeable directories have security issues. Avoid showing them in
the documentation since someone might accidentally use them in
situations where they are insecure.
There tend to be 3 security problems:
1. Denial of service. An adversary may be able to create the file
beforehand, consume all space/inodes, etc to sabotage us.
2. Impersonation. An adversary may be able to create a listen socket and
accept incoming connections that were meant for us.
3. Unauthenticated client access. An adversary may be able to connect to
us if we did not set the uid/gid and permissions correctly.
These can be prevented or mitigated with private /tmp, carefully setting
the umask, etc but that requires special action and does not apply to
all situations. Just avoid using /tmp in examples.
Reported-by: Richard W.M. Jones <rjones@redhat.com>
Reported-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20210301172728.135331-3-stefanha@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The QMP monitor, NBD server, and vhost-user-blk export all support file
descriptor passing. This is a useful technique because it allows the
parent process to spawn and wait for qemu-storage-daemon without busy
waiting, which may delay startup due to arbitrary sleep() calls.
This Python example is inspired by the test case written for libnbd by
Richard W.M. Jones <rjones@redhat.com>:
89113f484e
Thanks to Daniel P. Berrangé <berrange@redhat.com> for suggestions on
how to get this working. Now let's document it!
Reported-by: Richard W.M. Jones <rjones@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>
Cc: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20210301172728.135331-2-stefanha@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Daemons often have a --pidfile option where the pid is written to a file
so that scripts can stop the daemon by sending a signal.
The pid file also acts as a lock to prevent multiple instances of the
daemon from launching for a given pid file.
QEMU, qemu-nbd, qemu-ga, virtiofsd, and qemu-pr-helper all support the
--pidfile option. Add it to qemu-storage-daemon too.
Reported-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20210302142746.170535-1-stefanha@redhat.com>
Reviewed-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The preferred syntax is to use "foo=on|off", rather than a bare
"foo" or "nofoo".
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20210216191027.595031-8-berrange@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Document the qemu-storage-daemon tool. Most of the command-line options
are identical to their QEMU counterparts. Perhaps Sphinx hxtool
integration could be extended to extract documentation for individual
command-line options so they can be shared. For now the
qemu-storage-daemon simply refers to the qemu(1) man page where the
command-line options are identical.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20201209103802.350848-3-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
