linux-kernel - Re: [PATCH] fs/open: Fix most outstanding security bugs

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Date:   Mon, 1 Apr 2019 19:28:33 +0200
From:   Dmitry Vyukov <dvyukov@...gle.com>
To:     Nikolay Borisov <nborisov@...e.com>
Cc:     Johannes Thumshirn <jthumshirn@...e.de>,
        Linux Kernel Mailinglist <linux-kernel@...r.kernel.org>,
        Linux FSDEVEL Mailinglist <linux-fsdevel@...r.kernel.org>,
        stable <stable@...r.kernel.org>,
        syzkaller <syzkaller@...glegroups.com>
Subject: Re: [PATCH] fs/open: Fix most outstanding security bugs

On Mon, Apr 1, 2019 at 4:14 PM Nikolay Borisov <nborisov@...e.com> wrote:
> On 1.04.19 г. 12:01 ч., Johannes Thumshirn wrote:
> > Over the last 20 years, the Linux kernel has accumulated hundreds if not
> > thousands of security vulnerabilities.
> >
> > One common pattern in most of these security related reports is processes
> > called "syzkaller", "trinity" or "syz-executor" opening files and then
> > abuse kernel interfaces causing kernel crashes or even worse threats using
> > memory overwrites or by exploiting race conditions.
> >
> > Hunting down these bugs has become time consuming and very expensive, so
> > I've decided to put an end to it.
> >
> > If one of the above mentioned processes tries opening a file, return -EPERM
> > indicating this process does not have the permission to open files on Linux
> > anymore.
> >
> > Signed-off-by: Johannes Thumshirn <jthumshirn@...e.de>
>
> Ack-by: Nikolay Borisov <nborisov@...e.com>

Reviewed-by: Dmitry Vyukov <dvyukov@...gle.com>
Cc: stable@...r.kernel.org # v1.0+

Do we want to extend this to other subsystems?
Should it be a default secomp filter?

> > ---
> >  fs/open.c | 14 ++++++++++++++
> >  1 file changed, 14 insertions(+)
> >
> > diff --git a/fs/open.c b/fs/open.c
> > index f1c2f855fd43..3a3b460beccd 100644
> > --- a/fs/open.c
> > +++ b/fs/open.c
> > @@ -1056,6 +1056,20 @@ long do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode)
> >       struct open_flags op;
> >       int fd = build_open_flags(flags, mode, &op);
> >       struct filename *tmp;
> > +     char comm[TASK_COMM_LEN];
> > +     int i;
> > +     static const char * const list[] = {
> > +             "syzkaller",
> > +             "syz-executor,"
> > +             "trinity",
> > +             NULL
> > +     };
> > +
> > +     get_task_comm(comm, current);
> > +
> > +     for (i = 0; i < ARRAY_SIZE(list); i++)
> > +             if (!strncmp(comm, list[i], strlen(list[i])))
> > +                     return -EPERM;
> >
> >       if (fd)
> >               return fd;
> >