This makes it possible to write Polkit rules that won't
accidentally grant undesired privileges to users.
To understand why this is necessary, suppose we wanted to
grant user "fred" full access to the QEMU domain "demo".
A JavaScript rule along the lines of
polkit.addRule(function(action, subject) {
// user "fred"
if (subject.user == "fred") {
// can authenticate in read/write mode
if (action.id == "org.libvirt.unix.manage") {
return polkit.Result.YES;
}
// and manage the QEMU domain "demo"
if (action.id.indexOf("org.libvirt.api.domain.") == 0 &&
action.lookup("connect_driver") == "QEMU" &&
action.lookup("domain_name") == "demo") {
return polkit.Result.YES;
}
}
});
would do the trick.
However, suppose that at some point after creating this rule we
disabled the Polkit access control driver and forgot to delete
the file.
All of a sudden, allowing "org.libvirt.unix.manage" is no
longer a trivial matter: since the Polkit access driver doesn't
broker access to subsequent API calls anymore, user "fred" now
has full administrative access to all drivers.
Rewriting the check seen above as
if (action.id == "org.libvirt.unix.manage" &&
action.lookup("granular") == "true") {
return polkit.Result.YES;
}
ensures that this undesired scenario will not happen, by only
allowing "org.libvirt.unix.manage" when the Polkit access
driver is enabled.
Signed-off-by: Andrea Bolognani <abologna@xxxxxxxxxx>
---
src/remote/remote_daemon_dispatch.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/src/remote/remote_daemon_dispatch.c b/src/remote/remote_daemon_dispatch.c
index 7daf503b51..2a9ee19cc3 100644
--- a/src/remote/remote_daemon_dispatch.c
+++ b/src/remote/remote_daemon_dispatch.c
@@ -3975,6 +3975,10 @@ remoteDispatchAuthPolkit(virNetServer *server,
uid_t callerUid = -1;
unsigned long long timestamp;
const char *action;
+ const char *attrs[] = {
+ "granular", virNetServerHasGranularPolkit(server) ? "true" : "false",
+ NULL,
+ };
char *ident = NULL;
struct daemonClientPrivate *priv =
virNetServerClientGetPrivateData(client);
@@ -4009,7 +4013,7 @@ remoteDispatchAuthPolkit(virNetServer *server,
callerPid,
timestamp,
callerUid,
- NULL,
+ attrs,
true);
if (rv == -1)
goto authfail;
--
2.42.0
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