[PATCH RFC POC 36/50] nitro_enclaves: install the enclave descriptor when the ioctl returns

[Christian Brauner <brauner@kernel.org>]

Rely on the fd exit path machinery.

Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
---
 drivers/virt/nitro_enclaves/ne_misc_dev.c | 33 ++++++++++++-------------------
 1 file changed, 13 insertions(+), 20 deletions(-)

diff --git a/drivers/virt/nitro_enclaves/ne_misc_dev.c b/drivers/virt/nitro_enclaves/ne_misc_dev.c
index c91300a73f50..93c3f00f5443 100644
--- a/drivers/virt/nitro_enclaves/ne_misc_dev.c
+++ b/drivers/virt/nitro_enclaves/ne_misc_dev.c
@@ -1589,7 +1589,7 @@ static const struct file_operations ne_enclave_fops = {
 static int ne_create_vm_ioctl(struct ne_pci_dev *ne_pci_dev, u64 __user *slot_uid)
 {
 	struct ne_pci_dev_cmd_reply cmd_reply = {};
-	int enclave_fd = -1;
+	const struct fd_slot *enclave_fd = NULL;
 	struct file *enclave_file = NULL;
 	unsigned int i = 0;
 	struct ne_enclave *ne_enclave = NULL;
@@ -1647,9 +1647,9 @@ static int ne_create_vm_ioctl(struct ne_pci_dev *ne_pci_dev, u64 __user *slot_ui
 		goto free_cpumask;
 	}
 
-	enclave_fd = get_unused_fd_flags(O_CLOEXEC);
-	if (enclave_fd < 0) {
-		rc = enclave_fd;
+	enclave_fd = fd_prepare(O_CLOEXEC);
+	if (IS_ERR(enclave_fd)) {
+		rc = PTR_ERR(enclave_fd);
 
 		dev_err_ratelimited(ne_misc_dev.this_device,
 				    "Error in getting unused fd [rc=%d]\n", rc);
@@ -1664,7 +1664,7 @@ static int ne_create_vm_ioctl(struct ne_pci_dev *ne_pci_dev, u64 __user *slot_ui
 		dev_err_ratelimited(ne_misc_dev.this_device,
 				    "Error in anon inode get file [rc=%d]\n", rc);
 
-		goto put_fd;
+		goto free_cpumask;
 	}
 
 	rc = ne_do_request(pdev, SLOT_ALLOC,
@@ -1688,27 +1688,20 @@ static int ne_create_vm_ioctl(struct ne_pci_dev *ne_pci_dev, u64 __user *slot_ui
 
 	list_add(&ne_enclave->enclave_list_entry, &ne_pci_dev->enclaves_list);
 
-	if (copy_to_user(slot_uid, &ne_enclave->slot_uid, sizeof(ne_enclave->slot_uid))) {
-		/*
-		 * As we're holding the only reference to 'enclave_file', fput()
-		 * will call ne_enclave_release() which will do a proper cleanup
-		 * of all so far allocated resources, leaving only the unused fd
-		 * for us to free.
-		 */
-		fput(enclave_file);
-		put_unused_fd(enclave_fd);
+	fd_stage(enclave_fd, enclave_file);
 
+	/*
+	 * The failed ioctl drops the descriptor and with it the only reference
+	 * to 'enclave_file', so ne_enclave_release() does a proper cleanup of
+	 * all so far allocated resources.
+	 */
+	if (copy_to_user(slot_uid, &ne_enclave->slot_uid, sizeof(ne_enclave->slot_uid)))
 		return -EFAULT;
-	}
-
-	fd_install(enclave_fd, enclave_file);
 
-	return enclave_fd;
+	return fd_prepare_fd(enclave_fd);
 
 put_file:
 	fput(enclave_file);
-put_fd:
-	put_unused_fd(enclave_fd);
 free_cpumask:
 	free_cpumask_var(ne_enclave->vcpu_ids);
 	for (i = 0; i < ne_enclave->nr_parent_vm_cores; i++)

-- 
2.53.0