[PATCH] fuse: Support FS_IOC_GET_ENCRYPTION_POLICY_EX

[Chirantan Ekbote <chirantan@chromium.org>]

This is a dynamically sized ioctl so we need to check the user-provided
parameter for the actual length.

Signed-off-by: Chirantan Ekbote <chirantan@chromium.org>
---
 fs/fuse/file.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index c03034e8c1529..1627c14e9dacc 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -19,6 +19,7 @@
 #include <linux/falloc.h>
 #include <linux/uio.h>
 #include <linux/fs.h>
+#include <linux/fscrypt.h>
 
 static struct page **fuse_pages_alloc(unsigned int npages, gfp_t flags,
 				      struct fuse_page_desc **desc)
@@ -2808,6 +2809,21 @@ long fuse_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg,
 		case FS_IOC_SETFLAGS:
 			iov->iov_len = sizeof(int);
 			break;
+		case FS_IOC_GET_ENCRYPTION_POLICY_EX: {
+			struct fscrypt_get_policy_ex_arg policy;
+			unsigned long size_ptr =
+				arg + offsetof(struct fscrypt_get_policy_ex_arg,
+					       policy_size);
+
+			if (copy_from_user(&policy.policy_size,
+					   (void __user *)size_ptr,
+					   sizeof(policy.policy_size)))
+				return -EFAULT;
+
+			iov->iov_len =
+				sizeof(policy.policy_size) + policy.policy_size;
+			break;
+		}
 		default:
 			iov->iov_len = _IOC_SIZE(cmd);
 			break;
-- 
2.29.2.576.ga3fc446d84-goog