scm: Don't use struct ucred in NETLINK_CB and struct scm_cookie.
Passing uids and gids on NETLINK_CB from a process in one user
namespace to a process in another user namespace can result in the
wrong uid or gid being presented to userspace. Avoid that problem by
passing kuids and kgids instead.
- define struct scm_creds for use in scm_cookie and netlink_skb_parms
that holds uid and gid information in kuid_t and kgid_t.
- Modify scm_set_cred to fill out scm_creds by heand instead of using
cred_to_ucred to fill out struct ucred. This conversion ensures
userspace does not get incorrect uid or gid values to look at.
- Modify scm_recv to convert from struct scm_creds to struct ucred
before copying credential values to userspace.
- Modify __scm_send to populate struct scm_creds on in the scm_cookie,
instead of just copying struct ucred from userspace.
- Modify netlink_sendmsg to copy scm_creds instead of struct ucred
into the NETLINK_CB.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/netlink.h b/include/linux/netlink.h
index c9fdde2..df73cf4 100644
--- a/include/linux/netlink.h
+++ b/include/linux/netlink.h
@@ -153,6 +153,7 @@
#include <linux/capability.h>
#include <linux/skbuff.h>
+#include <net/scm.h>
struct net;
@@ -162,7 +163,7 @@
}
struct netlink_skb_parms {
- struct ucred creds; /* Skb credentials */
+ struct scm_creds creds; /* Skb credentials */
__u32 pid;
__u32 dst_group;
struct sock *ssk;