bus-proxy: don't fake data we don't have

UDS sockets transmit EUID+EGID only. Don't try to fake data we don't know!
Otherwise, this might be used to override user-limits by non-root setuid
programs (by faking UID==EUID).

Now that sd-bus is fixed to always use EUID even on UDS, we can safely set
all other UID/GID fields to INVALID.

diff --git a/src/bus-proxyd/proxy.c b/src/bus-proxyd/proxy.c
index 73f68b7874c28e901886e74aaff838602dbe30ef..4be2a6289aca7a738c93135b37ba30132dc3aad0 100644 (file)
--- a/src/bus-proxyd/proxy.c
+++ b/src/bus-proxyd/proxy.c
@@ -81,14 +81,14 @@ static int proxy_create_destination(Proxy *p, const char *destination, const cha
                 b->fake_pids.pid = p->local_creds.pid;
                 b->fake_pids_valid = true;
 
                 b->fake_pids.pid = p->local_creds.pid;
                 b->fake_pids_valid = true;
 

-                b->fake_creds.uid = p->local_creds.uid;
+                b->fake_creds.uid = UID_INVALID;

                 b->fake_creds.euid = p->local_creds.uid;
                 b->fake_creds.euid = p->local_creds.uid;

-                b->fake_creds.suid = p->local_creds.uid;
-                b->fake_creds.fsuid = p->local_creds.uid;
-                b->fake_creds.gid = p->local_creds.gid;
+                b->fake_creds.suid = UID_INVALID;
+                b->fake_creds.fsuid = UID_INVALID;
+                b->fake_creds.gid = GID_INVALID;

                 b->fake_creds.egid = p->local_creds.gid;
                 b->fake_creds.egid = p->local_creds.gid;

-                b->fake_creds.sgid = p->local_creds.gid;
-                b->fake_creds.fsgid = p->local_creds.gid;
+                b->fake_creds.sgid = GID_INVALID;
+                b->fake_creds.fsgid = GID_INVALID;

                 b->fake_creds_valid = true;
         }
 
                 b->fake_creds_valid = true;
         }