[Qemu-devel] [PATCH 5/6] vnc: allow specifying a custom authorization object name

["Daniel P. Berrangé" <berrange@redhat.com>]

From: "Daniel P. Berrange" <berrange@redhat.com>

The VNC server has historically had support for ACLs to check both the
SASL username and the TLS x509 distinguished name. The VNC server was
responsible for creating the initial ACL, and the client app was then
responsible for populating it with rules using the HMP 'acl_add' command.

This is not satisfactory for a variety of reasons. There is no way to
populate the ACLs from the command line, users are forced to use the
HMP. With multiple network services all supporting TLS and ACLs now, it
is desirable to be able to define a single ACL that is referenced by all
services.

To address these limitations, two new options are added to the VNC
server CLI. The 'tls-authz' option takes the ID of a QAuthZ object to
use for checking TLS x509 distinguished names, and the 'sasl-authz'
option takes the ID of another object to use for checking SASL usernames.

In this example, we setup two authorization rules. The first allows any
client with a certificate issued by the 'RedHat' organization in the
'London' locality. The second ACL allows clients with either the
'joe@REDHAT.COM' or  'fred@REDHAT.COM' kerberos usernames. Both checks
must pass for the user to be allowed.

    $QEMU -object tls-creds-x509,id=tls0,dir=/home/berrange/qemutls,\
                  endpoint=server,verify-peer=yes \
          -object authz-simple,id=authz0,policy=deny,\
                  rules.0.match=O=RedHat,,L=London,rules.0.policy=allow \
          -object authz-simple,id=authz1,policy=deny,\
                  rules.0.match=fred@REDHAT.COM,rules.0.policy=allow \
                  rules.0.match=joe@REDHAT.COM,rules.0.policy=allow \
          -vnc 0.0.0.0:1,tls-creds=tls0,tls-authz=authz0,
	       sasl,sasl-authz=authz1 \
          ...other QEMU args...

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
---
 qemu-doc.texi | 11 +++-------
 ui/vnc.c      | 58 +++++++++++++++++++++++++++++++++++++++++++--------
 2 files changed, 52 insertions(+), 17 deletions(-)

diff --git a/qemu-doc.texi b/qemu-doc.texi
index cd05760cac..5b7e3faab2 100644
--- a/qemu-doc.texi
+++ b/qemu-doc.texi
@@ -2917,15 +2917,10 @@ The @code{-localtime} option has been replaced by @code{-rtc base=localtime}.
 
 The @code{-startdate} option has been replaced by @code{-rtc base=@var{date}}.
 
-@subsection -virtioconsole (since 3.0.0)
+@subsection -vnc acl (since 3.0.0)
 
-Option @option{-virtioconsole} has been replaced by
-@option{-device virtconsole}.
-
-@subsection -clock (since 3.0.0)
-
-The @code{-clock} option is ignored since QEMU version 1.7.0. There is no
-replacement since it is not needed anymore.
+The @code{acl} option to the @code{-vnc} argument has been replaced
+by the @code{tls-authz} and @code{sasl-authz} options.
 
 @section QEMU Machine Protocol (QMP) commands
 
diff --git a/ui/vnc.c b/ui/vnc.c
index 9fb8430c35..2da9433ca7 100644
--- a/ui/vnc.c
+++ b/ui/vnc.c
@@ -3407,6 +3407,12 @@ static QemuOptsList qemu_vnc_opts = {
         },{
             .name = "acl",
             .type = QEMU_OPT_BOOL,
+        },{
+            .name = "tls-authz",
+            .type = QEMU_OPT_STRING,
+        },{
+            .name = "sasl-authz",
+            .type = QEMU_OPT_STRING,
         },{
             .name = "lossy",
             .type = QEMU_OPT_BOOL,
@@ -3894,6 +3900,8 @@ void vnc_display_open(const char *id, Error **errp)
     int saslErr;
 #endif
     int acl = 0;
+    const char *tlsauthz;
+    const char *saslauthz;
     int lock_key_sync = 1;
     int key_delay_ms;
 
@@ -3999,7 +4007,33 @@ void vnc_display_open(const char *id, Error **errp)
             }
         }
     }
+    if (qemu_opt_get(opts, "acl")) {
+        error_report("The 'acl' option to -vnc is deprecated. "
+                     "Please use the 'tls-authz' and 'sasl-authz' "
+                     "options instead");
+    }
     acl = qemu_opt_get_bool(opts, "acl", false);
+    tlsauthz = qemu_opt_get(opts, "tls-authz");
+    if (acl && tlsauthz) {
+        error_setg(errp, "'acl' option is mutually exclusive with the "
+                   "'tls-authz' option");
+        goto fail;
+    }
+    if (tlsauthz && !vd->tlscreds) {
+        error_setg(errp, "'tls-authz' provided but TLS is not enabled");
+        goto fail;
+    }
+
+    saslauthz = qemu_opt_get(opts, "sasl-authz");
+    if (acl && saslauthz) {
+        error_setg(errp, "'acl' option is mutually exclusive with the "
+                   "'sasl-authz' option");
+        goto fail;
+    }
+    if (saslauthz && !sasl) {
+        error_setg(errp, "'sasl-authz' provided but SASL auth is not enabled");
+        goto fail;
+    }
 
     share = qemu_opt_get(opts, "share");
     if (share) {
@@ -4029,7 +4063,9 @@ void vnc_display_open(const char *id, Error **errp)
         vd->non_adaptive = true;
     }
 
-    if (acl) {
+    if (tlsauthz) {
+        vd->tlsauthzid = g_strdup(tlsauthz);
+    } else if (acl) {
         if (strcmp(vd->id, "default") == 0) {
             vd->tlsauthzid = g_strdup("vnc.x509dname");
         } else {
@@ -4040,15 +4076,19 @@ void vnc_display_open(const char *id, Error **errp)
                                               &error_abort));
     }
 #ifdef CONFIG_VNC_SASL
-    if (acl && sasl) {
-        if (strcmp(vd->id, "default") == 0) {
-            vd->sasl.authzid = g_strdup("vnc.username");
-        } else {
-            vd->sasl.authzid = g_strdup_printf("vnc.%s.username", vd->id);
+    if (sasl) {
+        if (saslauthz) {
+            vd->sasl.authzid = g_strdup(saslauthz);
+        } else if (acl) {
+            if (strcmp(vd->id, "default") == 0) {
+                vd->sasl.authzid = g_strdup("vnc.username");
+            } else {
+                vd->sasl.authzid = g_strdup_printf("vnc.%s.username", vd->id);
+            }
+            vd->sasl.authz = QAUTHZ(qauthz_list_new(vd->sasl.authzid,
+                                                    QAUTHZ_LIST_POLICY_DENY,
+                                                    &error_abort));
         }
-        vd->sasl.authz = QAUTHZ(qauthz_list_new(vd->sasl.authzid,
-                                                QAUTHZ_LIST_POLICY_DENY,
-                                                &error_abort));
     }
 #endif
 
-- 
2.17.0