From: Vivek Goyal <vgoyal@redhat.com>
To: Stefan Hajnoczi <stefanha@redhat.com>
Cc: mszeredi@redhat.com, Daniel Berrange <berrange@redhat.com>,
slp@redhat.com, Greg Kurz <groug@kaod.org>,
qemu-devel@nongnu.org, virtio-fs@redhat.com,
Alex Xu <alex@alxu.ca>, P J P <ppandit@redhat.com>,
Laszlo Ersek <lersek@redhat.com>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>
Subject: Re: [PATCH v4 3/3] virtiofsd: prevent opening of special files (CVE-2020-35517)
Date: Wed, 3 Feb 2021 10:28:50 -0500 [thread overview]
Message-ID: <20210203152850.GA3307@redhat.com> (raw)
In-Reply-To: <20210203113719.83633-4-stefanha@redhat.com>
On Wed, Feb 03, 2021 at 11:37:19AM +0000, Stefan Hajnoczi wrote:
[..]
> @@ -1727,36 +1764,38 @@ static void lo_create(fuse_req_t req, fuse_ino_t parent, const char *name,
>
> update_open_flags(lo->writeback, lo->allow_direct_io, fi);
>
> - fd = openat(parent_inode->fd, name, (fi->flags | O_CREAT) & ~O_NOFOLLOW,
> - mode);
> + /* Try to create a new file but don't open existing files */
> + fd = openat(parent_inode->fd, name, fi->flags | O_CREAT | O_EXCL, mode);
> err = fd == -1 ? errno : 0;
> +
> lo_restore_cred(&old);
>
> - if (!err) {
> - ssize_t fh;
> -
> - pthread_mutex_lock(&lo->mutex);
> - fh = lo_add_fd_mapping(lo, fd);
> - pthread_mutex_unlock(&lo->mutex);
> - if (fh == -1) {
> - close(fd);
> - err = ENOMEM;
> - goto out;
> - }
> + /* Ignore the error if file exists and O_EXCL was not given */
> + if (err && !(err == EEXIST && !(fi->flags & O_EXCL))) {
Can this check be simplified to.
if (err && (err == EEXIST && (fi->flags & O_EXCL)) {
goto out;
}
> + goto out;
> + }
Vivek
next prev parent reply other threads:[~2021-02-03 15:31 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-03 11:37 [PATCH v4 0/3] virtiofsd: prevent opening of special files (CVE-2020-35517) Stefan Hajnoczi
2021-02-03 11:37 ` [PATCH v4 1/3] virtiofsd: extract lo_do_open() from lo_open() Stefan Hajnoczi
2021-02-03 14:20 ` Greg Kurz
2021-02-03 14:47 ` Dr. David Alan Gilbert
2021-02-03 15:45 ` Greg Kurz
2021-02-03 17:47 ` Greg Kurz
2021-02-03 16:57 ` Stefan Hajnoczi
2021-02-03 11:37 ` [PATCH v4 2/3] virtiofsd: optionally return inode pointer from lo_do_lookup() Stefan Hajnoczi
2021-02-03 14:20 ` Greg Kurz
2021-02-03 17:00 ` Stefan Hajnoczi
2021-02-04 8:25 ` Greg Kurz
2021-02-04 9:45 ` Stefan Hajnoczi
2021-02-04 11:19 ` Greg Kurz
2021-02-03 11:37 ` [PATCH v4 3/3] virtiofsd: prevent opening of special files (CVE-2020-35517) Stefan Hajnoczi
2021-02-03 15:28 ` Vivek Goyal [this message]
2021-02-03 16:02 ` Greg Kurz
2021-02-03 16:08 ` Vivek Goyal
2021-02-03 17:05 ` Stefan Hajnoczi
2021-02-03 18:05 ` Dr. David Alan Gilbert
2021-02-03 21:14 ` Vivek Goyal
2021-02-04 9:47 ` Stefan Hajnoczi
2021-02-03 15:57 ` Greg Kurz
2021-02-03 17:06 ` Stefan Hajnoczi
2021-02-03 11:46 ` [PATCH v4 0/3] " no-reply
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