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bus-proxy: never apply policy when sending signals

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Unlike dbus-daemon, the bus-proxy does not know the receiver of a
broadcast (as the kernel has exclusive access on the bus connections).
Hence, and "destination=" matches in dbus1 policies cannot be applied.

But kdbus does not place any restrictions on *SENDING* broadcasts, anyway.
The kernel never returns EPERM to KDBUS_CMD_SEND if KDBUS_MSG_SIGNAL is
set. Instead, receiver policies are checked. Hence, stop checking sender
policies for signals in bus-proxy and leave it up to the kernel.

This fixes some network-manager bus-proxy issues where NM uses weird
dst-based matches against interface-based matches. As we cannot perform
dst-based matches, our bus-proxy cannot properly implement this policy.
This commit is contained in:
David Herrmann 2015-07-01 18:31:18 +02:00 committed by Kay Sievers
parent 0204c4bd69
commit 3723263f49
1 changed files with 11 additions and 13 deletions
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24
src/bus-proxyd/proxy.c
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@ -494,7 +494,16 @@ static int process_policy_unlocked(sd_bus *from, sd_bus *to, sd_bus_message *m,
} }
/* First check if we (the sender) can send to this name */ /* First check if we (the sender) can send to this name */
if (policy_check_send(policy, our_ucred->uid, our_ucred->gid, m->header->type, NULL, destination_names, m->path, m->interface, m->member, true, &n)) { if (sd_bus_message_is_signal(m, NULL, NULL)) {
/* If we forward a signal from dbus-1 to kdbus, we have
* no idea who the recipient is. Therefore, we cannot
* apply any dbus-1 policies that match on receiver
* credentials. We know sd-bus always sets
* KDBUS_MSG_SIGNAL, so the kernel applies policies to
* the message. Therefore, skip policy checks in this
* case. */
return 0;
} else if (policy_check_send(policy, our_ucred->uid, our_ucred->gid, m->header->type, NULL, destination_names, m->path, m->interface, m->member, true, &n)) {
if (n) { if (n) {
/* If we made a receiver decision, then remember which /* If we made a receiver decision, then remember which
* name's policy we used, and to which unique ID it * name's policy we used, and to which unique ID it
@ -512,19 +521,8 @@ static int process_policy_unlocked(sd_bus *from, sd_bus *to, sd_bus_message *m,
return r; return r;
} }
if (sd_bus_message_is_signal(m, NULL, NULL)) { if (policy_check_recv(policy, destination_uid, destination_gid, m->header->type, owned_names, NULL, m->path, m->interface, m->member, true))
/* If we forward a signal from dbus-1 to kdbus,
* we have no idea who the recipient is.
* Therefore, we cannot apply any dbus-1
* receiver policies that match on receiver
* credentials. We know sd-bus always sets
* KDBUS_MSG_SIGNAL, so the kernel applies
* receiver policies to the message. Therefore,
* skip policy checks in this case. */
return 0; return 0;
} else if (policy_check_recv(policy, destination_uid, destination_gid, m->header->type, owned_names, NULL, m->path, m->interface, m->member, true)) {
return 0;
}
} }
/* Return an error back to the caller */ /* Return an error back to the caller */