[PATCH 3/7] SELinux: Stub in copy-up handling

[David Howells <dhowells@redhat.com>]

Provide stubs for union/overlay copy-up handling.  The xattr copy up stub
discards lower SELinux xattrs rather than letting them be copied up so that
the security label on the copy doesn't get corrupted.

Signed-off-by: David Howells <dhowells@redhat.com>
---

 security/selinux/hooks.c |   15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index e66314138b38..f3fe7dbbf741 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -3142,6 +3142,19 @@ static void selinux_inode_getsecid(const struct inode *inode, u32 *secid)
 	*secid = isec->sid;
 }
 
+static int selinux_inode_copy_up(struct dentry *src, struct dentry *dst)
+{
+	return 0;
+}
+
+static int selinux_inode_copy_up_xattr(struct dentry *src, struct dentry *dst,
+				       const char *name, void *value, size_t *size)
+{
+	if (strcmp(name, XATTR_NAME_SELINUX) == 0)
+		return 1; /* Discard */
+	return 0;
+}
+
 /* file security operations */
 
 static int selinux_revalidate_file_permission(struct file *file, int mask)
@@ -5868,6 +5881,8 @@ static struct security_operations selinux_ops = {
 	.inode_setsecurity =		selinux_inode_setsecurity,
 	.inode_listsecurity =		selinux_inode_listsecurity,
 	.inode_getsecid =		selinux_inode_getsecid,
+	.inode_copy_up =		selinux_inode_copy_up,
+	.inode_copy_up_xattr =		selinux_inode_copy_up_xattr,
 
 	.file_permission =		selinux_file_permission,
 	.file_alloc_security =		selinux_file_alloc_security,