Currently any client which can complete the TLS handshake is able to use the NBD server. The server admin can turn on the 'verify-peer' option for the x509 creds to require the client to provide a x509 certificate. This means the client will have to acquire a certificate from the CA before they are permitted to use the NBD server. This is still a fairly weak bar.
This adds a '--tls-acl ACL-ID' option to the qemu-nbd command which takes the ID of a previously added 'QAuthZ' object instance. This ACL will be used to validate the client's x509 distinguished name. Clients failing the ACL will not be permitted to use the NBD server. For example to setup an ACL that only allows connection from a client whose x509 certificate distinguished name contains 'CN=fred', you would use: qemu-nbd -object tls-creds-x509,id=tls0,dir=/home/berrange/qemutls,\ endpoint=server,verify-peer=yes \ -object authz-simple,id=acl0,policy=deny,\ rules.0.match=*CN=fred,rules.0.policy=allow \ -tls-creds tls0 \ -tls-acl acl0 ....other qemu-nbd args... Signed-off-by: Daniel P. Berrange <berra...@redhat.com> --- qemu-nbd.c | 13 ++++++++++++- qemu-nbd.texi | 4 ++++ 2 files changed, 16 insertions(+), 1 deletion(-) diff --git a/qemu-nbd.c b/qemu-nbd.c index 933ca4a..4f202f3 100644 --- a/qemu-nbd.c +++ b/qemu-nbd.c @@ -43,6 +43,7 @@ #define QEMU_NBD_OPT_DETECT_ZEROES 4 #define QEMU_NBD_OPT_OBJECT 5 #define QEMU_NBD_OPT_TLSCREDS 6 +#define QEMU_NBD_OPT_TLSACL 7 static NBDExport *exp; static bool newproto; @@ -56,6 +57,7 @@ static int nb_fds; static QIOChannelSocket *server_ioc; static int server_watch = -1; static QCryptoTLSCreds *tlscreds; +static const char *tlsacl; static void usage(const char *name) { @@ -344,7 +346,7 @@ static gboolean nbd_accept(QIOChannel *ioc, GIOCondition cond, gpointer opaque) nb_fds++; nbd_update_server_watch(); nbd_client_new(newproto ? NULL : exp, cioc, - tlscreds, NULL, nbd_client_closed); + tlscreds, tlsacl, nbd_client_closed); object_unref(OBJECT(cioc)); return TRUE; @@ -475,6 +477,7 @@ int main(int argc, char **argv) { "object", 1, NULL, QEMU_NBD_OPT_OBJECT }, { "export-name", 1, NULL, 'x' }, { "tls-creds", 1, NULL, QEMU_NBD_OPT_TLSCREDS }, + { "tls-acl", 1, NULL, QEMU_NBD_OPT_TLSACL }, { NULL, 0, NULL, 0 } }; int ch; @@ -672,6 +675,9 @@ int main(int argc, char **argv) case QEMU_NBD_OPT_TLSCREDS: tlscredsid = optarg; break; + case QEMU_NBD_OPT_TLSACL: + tlsacl = optarg; + break; } } @@ -708,6 +714,11 @@ int main(int argc, char **argv) error_get_pretty(local_err)); exit(EXIT_FAILURE); } + } else { + if (tlsacl) { + error_report("--tls-acl is not permitted without --tls-creds"); + exit(EXIT_FAILURE); + } } if (disconnect) { diff --git a/qemu-nbd.texi b/qemu-nbd.texi index 227a73c..935d0d3 100644 --- a/qemu-nbd.texi +++ b/qemu-nbd.texi @@ -81,6 +81,10 @@ the new style NBD protocol negotiation Enable mandatory TLS encryption for the server by setting the ID of the TLS credentials object previously created with the --object option. +@item --tls-acl=ID +Specify the ID of a qauthz object previously created with the +--object option. This will be used to authorize users who +connect against their x509 distinguish name. @item -v, --verbose Display extra debugging information @item -h, --help -- 2.5.0