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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Michal Suchanek <msuchanek@suse.de>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.16 0398/1039] debugfs: lockdown: Allow reading debugfs files that are not world readable
Date:   Mon, 24 Jan 2022 19:36:27 +0100
Message-Id: <20220124184138.697023872@linuxfoundation.org>
In-Reply-To: <20220124184125.121143506@linuxfoundation.org>
References: <20220124184125.121143506@linuxfoundation.org>
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From: Michal Suchanek <msuchanek@suse.de>

[ Upstream commit 358fcf5ddbec4e6706405847d6a666f5933a6c25 ]

When the kernel is locked down the kernel allows reading only debugfs
files with mode 444. Mode 400 is also valid but is not allowed.

Make the 444 into a mask.

Fixes: 5496197f9b08 ("debugfs: Restrict debugfs when the kernel is locked down")
Signed-off-by: Michal Suchanek <msuchanek@suse.de>
Link: https://lore.kernel.org/r/20220104170505.10248-1-msuchanek@suse.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/debugfs/file.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c
index 7d162b0efbf03..950c63fa4d0b2 100644
--- a/fs/debugfs/file.c
+++ b/fs/debugfs/file.c
@@ -147,7 +147,7 @@ static int debugfs_locked_down(struct inode *inode,
 			       struct file *filp,
 			       const struct file_operations *real_fops)
 {
-	if ((inode->i_mode & 07777) == 0444 &&
+	if ((inode->i_mode & 07777 & ~0444) == 0 &&
 	    !(filp->f_mode & FMODE_WRITE) &&
 	    !real_fops->unlocked_ioctl &&
 	    !real_fops->compat_ioctl &&
-- 
2.34.1