[Devel] [PATCH 5/6] add user mismatch test

[Glauber Costa]

In theory, we won't be able to run if our private area is not owned by
ourselves.  We could, if it have very wide open security permissions, but we
should never set up a container like that.

Aside from a basic sanity check, this is intended to catch problems for the few
people who may have already created containers that will be owned by root:root,
and will now try to run it unprivileged.

Signed-off-by: Glauber Costa <glommer at parallels.com>
---
 src/lib/env.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/src/lib/env.c b/src/lib/env.c
index 75e2dee..bca9c31 100644
--- a/src/lib/env.c
+++ b/src/lib/env.c
@@ -30,6 +30,7 @@
 #include <linux/reboot.h>
 #include <sys/mount.h>
 #include <sys/utsname.h>
+#include <sys/stat.h>
 
 #include "vzerror.h"
 #include "res.h"
@@ -567,6 +568,18 @@ int vps_start_custom(vps_handler *h, envid_t veid, vps_param *param,
 		logger(-1, 0, "Container is already running");
 		return VZ_VE_RUNNING;
 	}
+	if (!is_vz_kernel(h) && h->can_join_userns) {
+		struct stat private_stat;
+		stat(res->fs.private, &private_stat);
+		if ((private_stat.st_uid != res->misc.local_uid) ||
+			(private_stat.st_gid != res->misc.local_gid)) {
+			logger(-1, 0, "Container private area is owned by %d:%d"
+			", but configuration file says we should run with %lu:%lu.\n"
+			"Refusing to run.", private_stat.st_uid, private_stat.st_gid,
+			res->misc.local_uid, res->misc.local_gid);
+			return VZ_FS_BAD_TMPL;
+		}
+	}
 	if ((ret = check_ub(h, &res->ub)))
 		return ret;
 
-- 
1.7.11.7