[PATCH 2/3] selinux: Implement the object_init_security hook

[Ondrej Mosnacek]

The hook applies the same logic as selinux_determine_inode_label(), with
the exception of the super_block handling, which will be enforced on the
actual inodes by other hooks.

Signed-off-by: Ondrej Mosnacek <omosnace at redhat.com>
---
 security/selinux/hooks.c | 41 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 7ce012d9ec51..29c038513504 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -3526,6 +3526,45 @@ static int selinux_inode_copy_up_xattr(const char *name)
 	return -EOPNOTSUPP;
 }
 
+/* file-like object operations */
+
+/* Used e.g. for kernfs_node for newly created nodes */
+static int selinux_object_init_security(void *parent_ctx, u32 parent_ctxlen,
+					const struct qstr *qstr, u16 mode,
+					void **ctx, u32 *ctxlen)
+{
+	const struct task_security_struct *tsec = current_security();
+	u32 parent_sid, newsid, clen;
+	int rc;
+	char *context;
+
+	rc = security_context_to_sid(&selinux_state, parent_ctx, parent_ctxlen,
+				     &parent_sid, GFP_KERNEL);
+	if (rc)
+		return rc;
+
+	if (tsec->create_sid) {
+		newsid = tsec->create_sid;
+	} else {
+		u16 secclass = inode_mode_to_security_class(mode);
+
+		rc = security_transition_sid(&selinux_state, tsec->sid,
+					     parent_sid, secclass, qstr,
+					     &newsid);
+		if (rc)
+			return rc;
+	}
+
+	rc = security_sid_to_context_force(&selinux_state, newsid,
+					   &context, &clen);
+	if (rc)
+		return rc;
+
+	*ctx = context;
+	*ctxlen = clen;
+	return 0;
+}
+
 /* file security operations */
 
 static int selinux_revalidate_file_permission(struct file *file, int mask)
@@ -6965,6 +7004,8 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
 	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(object_init_security, selinux_object_init_security),
+
 	LSM_HOOK_INIT(file_permission, selinux_file_permission),
 	LSM_HOOK_INIT(file_alloc_security, selinux_file_alloc_security),
 	LSM_HOOK_INIT(file_free_security, selinux_file_free_security),
-- 
2.20.1