[PATCH] [RFC] virSetUIDGID: Don't leak supplementary groups

[Richard Weinberger <richard@xxxxxx>]

The LXC driver uses virSetUIDGID() to become UID/GID 0.
It passes an empty groups list to virSetUIDGID()
to get rid of all supplementary groups from the host side.
But virSetUIDGID() calls setgroups() only if the supplied list
is larger than 0.
This leads to a container root with unrelated supplementary groups.
In most cases this issue is unoticed as libvirtd runs as UID/GID 0
without any supplementary groups.

Signed-off-by: Richard Weinberger <richard@xxxxxx>
---
I've marked that patch as RFC as I'm not sure if all users of virSetUIDGID()
expect this behavior too.

Thanks,
//richard
---
 src/util/virutil.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/util/virutil.c b/src/util/virutil.c
index cddc78a..ea697a3 100644
--- a/src/util/virutil.c
+++ b/src/util/virutil.c
@@ -1103,7 +1103,7 @@ virSetUIDGID(uid_t uid, gid_t gid, gid_t *groups ATTRIBUTE_UNUSED,
     }
 
 # if HAVE_SETGROUPS
-    if (ngroups && setgroups(ngroups, groups) < 0) {
+    if (setgroups(ngroups, groups) < 0) {
         virReportSystemError(errno, "%s",
                              _("cannot set supplemental groups"));
         return -1;
-- 
2.4.2

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