Support ACLs for controlling VNC access ("Daniel P. Berrange")

This patch introduces a generic internal API for access control lists
to be used by network servers in QEMU. It adds support for checking
these ACL in the VNC server, in two places. The first ACL is for the
SASL authentication mechanism, checking the SASL username. This ACL
is called 'vnc.username'. The second is for the TLS authentication
mechanism, when x509 client certificates are turned on, checking against
the Distinguished Name of the client. This ACL is called 'vnc.x509dname'

The internal API provides for an ACL with the following characteristics

 - A unique name, eg  vnc.username, and vnc.x509dname.
 - A default policy, allow or deny
 - An ordered series of match rules, with allow or deny policy

If none of the match rules apply, then the default policy is
used.

There is a monitor API to manipulate the ACLs, which I'll describe via
examples

  (qemu) acl show vnc.username
  policy: allow
  (qemu) acl policy vnc.username denya
  acl: policy set to 'deny'
  (qemu) acl allow vnc.username fred
  acl: added rule at position 1
  (qemu) acl allow vnc.username bob
  acl: added rule at position 2
  (qemu) acl allow vnc.username joe 1
  acl: added rule at position 1
  (qemu) acl show vnc.username
  policy: deny
  0: allow fred
  1: allow joe
  2: allow bob


  (qemu) acl show vnc.x509dname
  policy: allow
  (qemu) acl policy vnc.x509dname deny
  acl: policy set to 'deny'
  (qemu) acl allow vnc.x509dname C=GB,O=ACME,L=London,CN=*
  acl: added rule at position 1
  (qemu) acl allow vnc.x509dname C=GB,O=ACME,L=Boston,CN=bob
  acl: added rule at position 2
  (qemu) acl show vnc.x509dname
  policy: deny
  0: allow C=GB,O=ACME,L=London,CN=*
  1: allow C=GB,O=ACME,L=Boston,CN=bob

By default the VNC server will not use any ACLs, allowing access to
the server if the user successfully authenticates. To enable use of
ACLs to restrict user access, the ',acl' flag should be given when
starting QEMU. The initial ACL activated will be a 'deny all' policy
and should be customized using monitor commands.

eg enable SASL auth and ACLs

    qemu ....  -vnc localhost:1,sasl,acl

The next patch will provide a way to load a pre-defined ACL when
starting up


 Makefile        |    6 +
 b/acl.c         |  185 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 b/acl.h         |   74 ++++++++++++++++++++++
 configure       |   18 +++++
 monitor.c       |   95 ++++++++++++++++++++++++++++
 qemu-doc.texi   |   49 ++++++++++++++
 vnc-auth-sasl.c |   16 +++-
 vnc-auth-sasl.h |    7 ++
 vnc-tls.c       |   19 +++++
 vnc-tls.h       |    3 
 vnc.c           |   21 ++++++
 vnc.h           |    3 
 12 files changed, 491 insertions(+), 5 deletions(-)

   Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6726 c046a42c-6fe2-441c-8c8c-71466251a162

1 files changed, 96 insertions, 0 deletions

diff --git a/monitor.c b/monitor.c
index 85da2390b1..3d81fbc887 100644
--- a/monitor.c
+++ b/monitor.c
@@ -41,6 +41,7 @@
 #include "qemu-timer.h"
 #include "migration.h"
 #include "kvm.h"
+#include "acl.h"
 
 //#define DEBUG
 //#define DEBUG_COMPLETION
@@ -1532,6 +1533,86 @@ static void do_info_balloon(Monitor *mon)
         monitor_printf(mon, "balloon: actual=%d\n", (int)(actual >> 20));
 }
 
+static void do_acl(Monitor *mon,
+                   const char *command,
+		   const char *aclname,
+		   const char *match,
+		   int has_index,
+		   int index)
+{
+    qemu_acl *acl;
+
+    acl = qemu_acl_find(aclname);
+    if (!acl) {
+	monitor_printf(mon, "acl: unknown list '%s'\n", aclname);
+	return;
+    }
+
+    if (strcmp(command, "show") == 0) {
+	int i = 0;
+	qemu_acl_entry *entry;
+	monitor_printf(mon, "policy: %s\n",
+                       acl->defaultDeny ? "deny" : "allow");
+	TAILQ_FOREACH(entry, &acl->entries, next) {
+	    i++;
+	    monitor_printf(mon, "%d: %s %s\n", i,
+                           entry->deny ? "deny" : "allow",
+                           entry->match);
+	}
+    } else if (strcmp(command, "reset") == 0) {
+	qemu_acl_reset(acl);
+	monitor_printf(mon, "acl: removed all rules\n");
+    } else if (strcmp(command, "policy") == 0) {
+	if (!match) {
+	    monitor_printf(mon, "acl: missing policy parameter\n");
+	    return;
+	}
+
+	if (strcmp(match, "allow") == 0) {
+	    acl->defaultDeny = 0;
+	    monitor_printf(mon, "acl: policy set to 'allow'\n");
+	} else if (strcmp(match, "deny") == 0) {
+	    acl->defaultDeny = 1;
+	    monitor_printf(mon, "acl: policy set to 'deny'\n");
+	} else {
+	    monitor_printf(mon, "acl: unknown policy '%s', expected 'deny' or 'allow'\n", match);
+	}
+    } else if ((strcmp(command, "allow") == 0) ||
+	       (strcmp(command, "deny") == 0)) {
+	int deny = strcmp(command, "deny") == 0 ? 1 : 0;
+	int ret;
+
+	if (!match) {
+	    monitor_printf(mon, "acl: missing match parameter\n");
+	    return;
+	}
+
+	if (has_index)
+	    ret = qemu_acl_insert(acl, deny, match, index);
+	else
+	    ret = qemu_acl_append(acl, deny, match);
+	if (ret < 0)
+	    monitor_printf(mon, "acl: unable to add acl entry\n");
+	else
+	    monitor_printf(mon, "acl: added rule at position %d\n", ret);
+    } else if (strcmp(command, "remove") == 0) {
+	int ret;
+
+	if (!match) {
+	    monitor_printf(mon, "acl: missing match parameter\n");
+	    return;
+	}
+
+	ret = qemu_acl_remove(acl, match);
+	if (ret < 0)
+	    monitor_printf(mon, "acl: no matching acl entry\n");
+	else
+	    monitor_printf(mon, "acl: removed rule at position %d\n", ret);
+    } else {
+	monitor_printf(mon, "acl: unknown command '%s'\n", command);
+    }
+}
+
 /* Please update qemu-doc.texi when adding or changing commands */
 static const mon_cmd_t mon_cmds[] = {
     { "help|?", "s?", help_cmd,
@@ -1636,6 +1717,12 @@ static const mon_cmd_t mon_cmds[] = {
       "target", "request VM to change it's memory allocation (in MB)" },
     { "set_link", "ss", do_set_link,
       "name [up|down]", "change the link status of a network adapter" },
+    { "acl", "sss?i?", do_acl, "<command> <aclname> [<match>] [<index>]\n",
+                               "acl show vnc.username\n"
+                               "acl policy vnc.username deny\n"
+                               "acl allow vnc.username fred\n"
+                               "acl deny vnc.username bob\n"
+                               "acl reset vnc.username\n" },
     { NULL, NULL, },
 };
 
@@ -2961,6 +3048,15 @@ static void monitor_event(void *opaque, int event)
     }
 }
 
+
+/*
+ * Local variables:
+ *  c-indent-level: 4
+ *  c-basic-offset: 4
+ *  tab-width: 8
+ * End:
+ */
+
 void monitor_init(CharDriverState *chr, int flags)
 {
     static int is_first_init = 1;