qga: add guest-set-user-password command

Add a new 'guest-set-user-password' command for changing the password
of guest OS user accounts. This command is needed to enable OpenStack
to support its API for changing the admin password of guests running
on KVM/QEMU. It is not practical to provide a command at the QEMU
level explicitly targetting administrator account password change
only, since different guest OS have different names for the admin
account. While UNIX systems use 'root', Windows systems typically
use 'Administrator' and even that can be renamed. Higher level apps
like OpenStack have the ability to figure out the correct admin
account name since they have info that QEMU/libvirt do not.

The command accepts either the clear text password string, encoded
in base64 to make it 8-bit safe in JSON:

$ echo -n "123456" | base64
MTIzNDU2
$ virsh -c qemu:///system  qemu-agent-command f21x86_64 \
   '{ "execute": "guest-set-user-password",
      "arguments": { "crypted": false,
                     "username": "root",
                     "password": "MTIzNDU2" } }'
  {"return":{}}

Or a password that has already been run though a crypt(3) like
algorithm appropriate for the guest, again then base64 encoded:

$ echo -n '$6$n01A2Tau$e...snip...DfMOP7of9AJ1I8q0' | base64
JDYkb...snip...YT2Ey
$ virsh -c qemu:///system  qemu-agent-command f21x86_64 \
   '{ "execute": "guest-set-user-password",
      "arguments": { "crypted": true,
                     "username": "root",
                     "password": "JDYkb...snip...YT2Ey" } }'

NB windows support is desirable, but not implemented in this
patch.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

1 files changed, 27 insertions, 0 deletions

diff --git a/qga/qapi-schema.json b/qga/qapi-schema.json
index 376e79f583..5117b65b26 100644
--- a/qga/qapi-schema.json
+++ b/qga/qapi-schema.json
@@ -738,3 +738,30 @@
 ##
 { 'command': 'guest-get-fsinfo',
   'returns': ['GuestFilesystemInfo'] }
+
+##
+# @guest-set-user-password
+#
+# @username: the user account whose password to change
+# @password: the new password entry string, base64 encoded
+# @crypted: true if password is already crypt()d, false if raw
+#
+# If the @crypted flag is true, it is the caller's responsibility
+# to ensure the correct crypt() encryption scheme is used. This
+# command does not attempt to interpret or report on the encryption
+# scheme. Refer to the documentation of the guest operating system
+# in question to determine what is supported.
+#
+# Note all guest operating systems will support use of the
+# @crypted flag, as they may require the clear-text password
+#
+# The @password parameter must always be base64 encoded before
+# transmission, even if already crypt()d, to ensure it is 8-bit
+# safe when passed as JSON.
+#
+# Returns: Nothing on success.
+#
+# Since 2.3
+##
+{ 'command': 'guest-set-user-password',
+  'data': { 'username': 'str', 'password': 'str', 'crypted': 'bool' } }