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Message-ID: <b7a77d4f-32de-af24-ed5c-8a3e49947c5a@oracle.com>
Date:   Thu, 18 Aug 2022 19:51:46 -0700
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Subject: Re: [RFC] problems with alloc_file_pseudo() use in __nfs42_ssc_open()
Content-Language: en-US
To:     Olga Kornievskaia <aglo@umich.edu>,
        Al Viro <viro@zeniv.linux.org.uk>
Cc:     Amir Goldstein <amir73il@gmail.com>,
        linux-nfs <linux-nfs@vger.kernel.org>,
        Olga Kornievskaia <kolga@netapp.com>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>
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On 8/18/22 6:13 AM, Olga Kornievskaia wrote:
> On Thu, Aug 18, 2022 at 1:52 AM Al Viro <viro@zeniv.linux.org.uk> wrote:
>> On Thu, Aug 18, 2022 at 08:19:54AM +0300, Amir Goldstein wrote:
>>
>>> NFS spec does not guarantee the safety of the server.
>>> It's like saying that the Law makes Crime impossible.
>>> The law needs to be enforced, so if server gets a request
>>> to COPY from/to an fhandle that resolves as a non-regular file
>>> (from a rogue or buggy NFS client) the server should return an
>>> error and not continue to alloc_file_pseudo().
>> FWIW, my preference would be to have alloc_file_pseudo() reject
>> directory inodes if it ever gets such.
>>
>> I'm still not sure that my (and yours, apparently) interpretation
>> of what Olga said is correct, though.
> Would it be appropriate to do the following then:
>
> diff --git a/fs/nfs/nfs4file.c b/fs/nfs/nfs4file.c
> index e88f6b18445e..112134b6438d 100644
> --- a/fs/nfs/nfs4file.c
> +++ b/fs/nfs/nfs4file.c
> @@ -340,6 +340,11 @@ static struct file *__nfs42_ssc_open(struct
> vfsmount *ss_mnt,
>                  goto out;
>          }
>
> +       if (S_ISDIR(fattr->mode)) {
> +               res = ERR_PTR(-EBADF);
> +               goto out;
> +       }
> +

Can we also enhance nfsd4_do_async_copy to check for
-EBADF and returns nfserr_wrong_type? perhaps adding
an error mapping function to handle other errors also.

-Dai

>          res = ERR_PTR(-ENOMEM);
>          len = strlen(SSC_READ_NAME_BODY) + 16;
>          read_name = kzalloc(len, GFP_KERNEL);
> @@ -357,6 +362,7 @@ static struct file *__nfs42_ssc_open(struct
> vfsmount *ss_mnt,
>                                       r_ino->i_fop);
>          if (IS_ERR(filep)) {
>                  res = ERR_CAST(filep);
> +               iput(r_ino);
>                  goto out_free_name;
>          }