linux-kernel - [PATCH AUTOSEL 6.10 45/70] fuse: handle idmappings properly in ->write

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Message-ID: <20241004182200.3670903-45-sashal@kernel.org>
Date: Fri,  4 Oct 2024 14:20:43 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@...onical.com>,
	Miklos Szeredi <mszeredi@...hat.com>,
	Sasha Levin <sashal@...nel.org>,
	miklos@...redi.hu,
	linux-fsdevel@...r.kernel.org
Subject: [PATCH AUTOSEL 6.10 45/70] fuse: handle idmappings properly in ->write_iter()

From: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@...onical.com>

[ Upstream commit 5b8ca5a54cb89ab07b0389f50e038e533cdfdd86 ]

This is needed to properly clear suid/sgid.

Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@...onical.com>
Signed-off-by: Miklos Szeredi <mszeredi@...hat.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/fuse/file.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index ed76121f73f2e..536194d41b0b7 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1398,6 +1398,7 @@ static void fuse_dio_unlock(struct kiocb *iocb, bool exclusive)
 static ssize_t fuse_cache_write_iter(struct kiocb *iocb, struct iov_iter *from)
 {
 	struct file *file = iocb->ki_filp;
+	struct mnt_idmap *idmap = file_mnt_idmap(file);
 	struct address_space *mapping = file->f_mapping;
 	ssize_t written = 0;
 	struct inode *inode = mapping->host;
@@ -1412,7 +1413,7 @@ static ssize_t fuse_cache_write_iter(struct kiocb *iocb, struct iov_iter *from)
 			return err;
 
 		if (fc->handle_killpriv_v2 &&
-		    setattr_should_drop_suidgid(&nop_mnt_idmap,
+		    setattr_should_drop_suidgid(idmap,
 						file_inode(file))) {
 			goto writethrough;
 		}
-- 
2.43.0