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From: Vivek Goyal <vgoyal@redhat.com>
To: Miklos Szeredi <miklos@szeredi.hu>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	kvm@vger.kernel.org, linux-nvdimm@lists.01.org,
	stefanha@redhat.com, dgilbert@redhat.com, swhiteho@redhat.com
Subject: Re: [PATCH v2 02/30] fuse: Clear setuid bit even in cache=never path
Date: Tue, 21 May 2019 11:01:31 -0400
Message-ID: <20190521150131.GB29075@redhat.com> (raw)
In-Reply-To: <20190520144137.GA24093@localhost.localdomain>

On Mon, May 20, 2019 at 04:41:37PM +0200, Miklos Szeredi wrote:
> On Wed, May 15, 2019 at 03:26:47PM -0400, Vivek Goyal wrote:
> > If fuse daemon is started with cache=never, fuse falls back to direct IO.
> > In that write path we don't call file_remove_privs() and that means setuid
> > bit is not cleared if unpriviliged user writes to a file with setuid bit set.
> > 
> > pjdfstest chmod test 12.t tests this and fails.
> 
> I think better sulution is to tell the server if the suid bit needs to be
> removed, so it can do so in a race free way.
> 
> Here's the kernel patch, and I'll reply with the libfuse patch.

Hi Miklos,

I tested and it works for me.

Vivek

> 
> ---
>  fs/fuse2/file.c           |    2 ++
>  include/uapi/linux/fuse.h |    3 +++
>  2 files changed, 5 insertions(+)
> 
> --- a/fs/fuse2/file.c
> +++ b/fs/fuse2/file.c
> @@ -363,6 +363,8 @@ static ssize_t fuse_send_write(struct fu
>  		inarg->flags |= O_DSYNC;
>  	if (iocb->ki_flags & IOCB_SYNC)
>  		inarg->flags |= O_SYNC;
> +	if (!capable(CAP_FSETID))
> +		inarg->write_flags |= FUSE_WRITE_KILL_PRIV;
>  	req->inh.opcode = FUSE_WRITE;
>  	req->inh.nodeid = ff->nodeid;
>  	req->inh.len = req->inline_inlen + count;
> --- a/include/uapi/linux/fuse.h
> +++ b/include/uapi/linux/fuse.h
> @@ -125,6 +125,7 @@
>   *
>   *  7.29
>   *  - add FUSE_NO_OPENDIR_SUPPORT flag
> + *  - add FUSE_WRITE_KILL_PRIV flag
>   */
>  
>  #ifndef _LINUX_FUSE_H
> @@ -318,9 +319,11 @@ struct fuse_file_lock {
>   *
>   * FUSE_WRITE_CACHE: delayed write from page cache, file handle is guessed
>   * FUSE_WRITE_LOCKOWNER: lock_owner field is valid
> + * FUSE_WRITE_KILL_PRIV: kill suid and sgid bits
>   */
>  #define FUSE_WRITE_CACHE	(1 << 0)
>  #define FUSE_WRITE_LOCKOWNER	(1 << 1)
> +#define FUSE_WRITE_KILL_PRIV	(1 << 2)
>  
>  /**
>   * Read flags
> 
> 

  parent reply index

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-15 19:26 [PATCH v2 00/30] [RFC] virtio-fs: shared file system for virtual machines Vivek Goyal
2019-05-15 19:26 ` [PATCH v2 01/30] fuse: delete dentry if timeout is zero Vivek Goyal
2019-05-15 19:26 ` [PATCH v2 02/30] fuse: Clear setuid bit even in cache=never path Vivek Goyal
2019-05-20 14:41   ` Miklos Szeredi
2019-05-20 14:44     ` Miklos Szeredi
2019-05-20 20:25       ` Nikolaus Rath
2019-05-21 15:01     ` Vivek Goyal [this message]
2019-05-15 19:26 ` [PATCH v2 03/30] fuse: Use default_file_splice_read for direct IO Vivek Goyal
2019-05-15 19:26 ` [PATCH v2 04/30] fuse: export fuse_end_request() Vivek Goyal
2019-05-15 19:26 ` [PATCH v2 05/30] fuse: export fuse_len_args() Vivek Goyal
2019-05-15 19:26 ` [PATCH v2 06/30] fuse: Export fuse_send_init_request() Vivek Goyal
2019-05-15 19:26 ` [PATCH v2 07/30] fuse: export fuse_get_unique() Vivek Goyal
2019-05-15 19:26 ` [PATCH v2 08/30] fuse: extract fuse_fill_super_common() Vivek Goyal
2019-05-15 19:26 ` [PATCH v2 09/30] fuse: add fuse_iqueue_ops callbacks Vivek Goyal
2019-05-15 19:26 ` [PATCH v2 10/30] fuse: Separate fuse device allocation and installation in fuse_conn Vivek Goyal
2019-05-15 19:26 ` [PATCH v2 11/30] virtio_fs: add skeleton virtio_fs.ko module Vivek Goyal
2019-05-15 19:26 ` [PATCH v2 12/30] dax: remove block device dependencies Vivek Goyal
2019-05-16  0:21   ` Dan Williams
2019-05-16 10:07     ` Stefan Hajnoczi
2019-05-16 14:23     ` Vivek Goyal
2019-05-15 19:26 ` [PATCH v2 13/30] dax: Pass dax_dev to dax_writeback_mapping_range() Vivek Goyal
2019-05-15 19:26 ` [PATCH v2 14/30] virtio: Add get_shm_region method Vivek Goyal
2019-05-15 19:27 ` [PATCH v2 15/30] virtio: Implement get_shm_region for PCI transport Vivek Goyal
2019-05-15 19:27 ` [PATCH v2 16/30] virtio: Implement get_shm_region for MMIO transport Vivek Goyal
2019-05-15 19:27 ` [PATCH v2 17/30] fuse, dax: add fuse_conn->dax_dev field Vivek Goyal
2019-05-15 19:27 ` [PATCH v2 18/30] virtio_fs, dax: Set up virtio_fs dax_device Vivek Goyal
2019-07-17 17:27   ` Halil Pasic
2019-07-18  9:04     ` Cornelia Huck
2019-07-18 11:20       ` Halil Pasic
2019-07-18 14:47         ` Cornelia Huck
2019-07-18 13:15     ` Vivek Goyal
2019-07-18 14:30       ` Dan Williams
2019-07-22 10:51         ` Christian Borntraeger
2019-07-22 10:56           ` Dr. David Alan Gilbert
2019-07-22 11:20             ` Christian Borntraeger
2019-07-22 11:43               ` Cornelia Huck
2019-07-22 12:00                 ` Christian Borntraeger
2019-07-22 12:08                   ` David Hildenbrand
2019-07-29 13:20                     ` Stefan Hajnoczi
2019-05-15 19:27 ` [PATCH v2 19/30] fuse: Keep a list of free dax memory ranges Vivek Goyal
2019-05-15 19:27 ` [PATCH v2 20/30] fuse: Introduce setupmapping/removemapping commands Vivek Goyal
2019-05-15 19:27 ` [PATCH v2 21/30] fuse, dax: Implement dax read/write operations Vivek Goyal
2019-05-15 19:27 ` [PATCH v2 22/30] fuse, dax: add DAX mmap support Vivek Goyal
2019-05-15 19:27 ` [PATCH v2 23/30] fuse: Define dax address space operations Vivek Goyal
2019-05-15 19:27 ` [PATCH v2 24/30] fuse, dax: Take ->i_mmap_sem lock during dax page fault Vivek Goyal
2019-05-15 19:27 ` [PATCH v2 25/30] fuse: Maintain a list of busy elements Vivek Goyal
2019-05-15 19:27 ` [PATCH v2 26/30] fuse: Add logic to free up a memory range Vivek Goyal
     [not found]   ` <CAN+Pk99SNKSf+GjSQUUWt_eu1fSjTy_ByUOEQUXHi8zNqXY1zA@mail.gmail.com>
2019-05-20 12:53     ` Vivek Goyal
2019-05-15 19:27 ` [PATCH v2 27/30] fuse: Release file in process context Vivek Goyal
2019-05-15 19:27 ` [PATCH v2 28/30] fuse: Reschedule dax free work if too many EAGAIN attempts Vivek Goyal
2019-05-15 19:27 ` [PATCH v2 29/30] fuse: Take inode lock for dax inode truncation Vivek Goyal
2019-05-15 19:27 ` [PATCH v2 30/30] virtio-fs: Do not provide abort interface in fusectl Vivek Goyal

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