selinux: Implementation for inode_copy_up_xattr() hook
When a file is copied up in overlay, we have already created file on
upper/ with right label and there is no need to copy up selinux
label/xattr from lower file to upper file. In fact in case of context
mount, we don't want to copy up label as newly created file got its label
from context= option.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <paul@paul-moore.com>
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 40597ed..a2d5108 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -3313,6 +3313,21 @@
return 0;
}
+static int selinux_inode_copy_up_xattr(const char *name)
+{
+ /* The copy_up hook above sets the initial context on an inode, but we
+ * don't then want to overwrite it by blindly copying all the lower
+ * xattrs up. Instead, we have to filter out SELinux-related xattrs.
+ */
+ if (strcmp(name, XATTR_NAME_SELINUX) == 0)
+ return 1; /* Discard */
+ /*
+ * Any other attribute apart from SELINUX is not claimed, supported
+ * by selinux.
+ */
+ return -EOPNOTSUPP;
+}
+
/* file security operations */
static int selinux_revalidate_file_permission(struct file *file, int mask)
@@ -6109,6 +6124,7 @@
LSM_HOOK_INIT(inode_listsecurity, selinux_inode_listsecurity),
LSM_HOOK_INIT(inode_getsecid, selinux_inode_getsecid),
LSM_HOOK_INIT(inode_copy_up, selinux_inode_copy_up),
+ LSM_HOOK_INIT(inode_copy_up_xattr, selinux_inode_copy_up_xattr),
LSM_HOOK_INIT(file_permission, selinux_file_permission),
LSM_HOOK_INIT(file_alloc_security, selinux_file_alloc_security),
