From db6a59ec4e016c75e30d3e85579d2b69f21a4bd7 Mon Sep 17 00:00:00 2001
From: 5ec1cff <56485584+5ec1cff@users.noreply.github.com>
Date: Sat, 15 Nov 2025 19:52:05 +0800
Subject: [PATCH] kernel: file_wrapper: copy mode of original inode

Bionic uses fstat to determine whether an fd is a tty and set proper
buffering flags, so we also need to set the wrapper file's inode mode to
the original inode mode.

see:
https://cs.android.com/android/platform/superproject/main/+/main:bionic/libc/upstream-openbsd/lib/libc/stdio/makebuf.c;l=61-95;drc=9a4b68e20d617b2cb3355071521f16e8c3d538df
---
 kernel/supercalls.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/supercalls.c b/kernel/supercalls.c
index f0143f86..9a91f140 100644
--- a/kernel/supercalls.c
+++ b/kernel/supercalls.c
@@ -399,6 +399,8 @@ static int do_get_wrapper_fd(void __user *arg) {
     struct file* pf = fget(ret);
 
     struct inode* wrapper_inode = file_inode(pf);
+    // copy original inode mode
+    wrapper_inode->i_mode = file_inode(f)->i_mode;
     struct inode_security_struct *sec = selinux_inode(wrapper_inode);
     if (sec) {
         sec->sid = ksu_file_sid;