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Message-ID: <CAOQ4uxjncBJ=+-2J70m5sPtLiCzdHZ_mNWr4tVgGTODsMuQCvQ@mail.gmail.com>
Date: Tue, 11 Feb 2025 21:30:39 +0100
From: Amir Goldstein <amir73il@...il.com>
To: Christian Brauner <brauner@...nel.org>
Cc: Zicheng Qu <quzicheng@...wei.com>, Linus Torvalds <torvalds@...ux-foundation.org>,
jlayton@...nel.org, axboe@...nel.dk, joel.granados@...nel.org,
tglx@...utronix.de, viro@...iv.linux.org.uk, hch@....de, len.brown@...el.com,
pavel@....cz, pengfei.xu@...el.com, rafael@...nel.org, tanghui20@...wei.com,
zhangqiao22@...wei.com, judy.chenhui@...wei.com, linux-kernel@...r.kernel.org,
linux-fsdevel@...r.kernel.org, syzkaller-bugs@...glegroups.com,
linux-pm@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH 2/2] acct: block access to kernel internal filesystems
On Tue, Feb 11, 2025 at 6:17 PM Christian Brauner <brauner@...nel.org> wrote:
>
> There's no point in allowing anything kernel internal nor procfs or
> sysfs.
>
> Reported-by: Zicheng Qu <quzicheng@...wei.com>
> Link: https://lore.kernel.org/r/20250127091811.3183623-1-quzicheng@huawei.com
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Cc: <stable@...r.kernel.org>
> Signed-off-by: Christian Brauner <brauner@...nel.org>
Reviewed-by: Amir Goldstein <amir73il@...il.com>
> ---
> kernel/acct.c | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
> diff --git a/kernel/acct.c b/kernel/acct.c
> index 48283efe8a12..6520baa13669 100644
> --- a/kernel/acct.c
> +++ b/kernel/acct.c
> @@ -243,6 +243,20 @@ static int acct_on(struct filename *pathname)
> return -EACCES;
> }
>
> + /* Exclude kernel kernel internal filesystems. */
> + if (file_inode(file)->i_sb->s_flags & (SB_NOUSER | SB_KERNMOUNT)) {
> + kfree(acct);
> + filp_close(file, NULL);
> + return -EINVAL;
> + }
> +
> + /* Exclude procfs and sysfs. */
> + if (file_inode(file)->i_sb->s_iflags & SB_I_USERNS_VISIBLE) {
> + kfree(acct);
> + filp_close(file, NULL);
> + return -EINVAL;
> + }
> +
> if (!(file->f_mode & FMODE_CAN_WRITE)) {
> kfree(acct);
> filp_close(file, NULL);
>
> --
> 2.47.2
>
>
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