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Message-ID: <2dbeb7b8-8994-d610-f536-58d41767a1ec@themaw.net>
Date:   Thu, 30 Jun 2022 08:41:55 +0800
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Subject: Re: [REPOST PATCH] nfs: fix port value parsing
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To:     Trond Myklebust <trondmy@hammerspace.com>,
        "Anna.Schumaker@Netapp.com" <Anna.Schumaker@Netapp.com>
Cc:     "linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>,
        "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
        "SteveD@redhat.com" <SteveD@redhat.com>,
        "bcodding@redhat.com" <bcodding@redhat.com>,
        "dhowells@redhat.com" <dhowells@redhat.com>
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From:   Ian Kent <raven@themaw.net>
In-Reply-To: <c81b95d2b68480ead9f3bb88d6cf5a82a43c73b8.camel@hammerspace.com>
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On 30/6/22 07:57, Trond Myklebust wrote:
> On Thu, 2022-06-30 at 07:33 +0800, Ian Kent wrote:
>> On 29/6/22 23:33, Trond Myklebust wrote:
>>> On Wed, 2022-06-29 at 09:02 +0800, Ian Kent wrote:
>>>> On 28/6/22 22:34, Trond Myklebust wrote:
>>>>> On Tue, 2022-06-28 at 08:25 +0800, Ian Kent wrote:
>>>>>> The valid values of nfs options port and mountport are 0 to
>>>>>> USHRT_MAX.
>>>>>>
>>>>>> The fs parser will return a fail for port values that are
>>>>>> negative
>>>>>> and the sloppy option handling then returns success.
>>>>>>
>>>>>> But the sloppy option handling is meant to return success for
>>>>>> invalid
>>>>>> options not valid options with invalid values.
>>>>>>
>>>>>> Parsing these values as s32 rather than u32 prevents the
>>>>>> parser
>>>>>> from
>>>>>> returning a parse fail allowing the later USHRT_MAX option
>>>>>> check
>>>>>> to
>>>>>> correctly return a fail in this case. The result check could
>>>>>> be
>>>>>> changed
>>>>>> to use the int_32 union variant as well but leaving it as a
>>>>>> uint_32
>>>>>> check avoids using two logical compares instead of one.
>>>>>>
>>>>>> Signed-off-by: Ian Kent <raven@themaw.net>
>>>>>> ---
>>>>>>     fs/nfs/fs_context.c |    4 ++--
>>>>>>     1 file changed, 2 insertions(+), 2 deletions(-)
>>>>>>
>>>>>> diff --git a/fs/nfs/fs_context.c b/fs/nfs/fs_context.c
>>>>>> index 9a16897e8dc6..f4da1d2be616 100644
>>>>>> --- a/fs/nfs/fs_context.c
>>>>>> +++ b/fs/nfs/fs_context.c
>>>>>> @@ -156,14 +156,14 @@ static const struct fs_parameter_spec
>>>>>> nfs_fs_parameters[] = {
>>>>>>            fsparam_u32   ("minorversion",  Opt_minorversion),
>>>>>>            fsparam_string("mountaddr",     Opt_mountaddr),
>>>>>>            fsparam_string("mounthost",     Opt_mounthost),
>>>>>> -       fsparam_u32   ("mountport",     Opt_mountport),
>>>>>> +       fsparam_s32   ("mountport",     Opt_mountport),
>>>>>>            fsparam_string("mountproto",    Opt_mountproto),
>>>>>>            fsparam_u32   ("mountvers",     Opt_mountvers),
>>>>>>            fsparam_u32   ("namlen",        Opt_namelen),
>>>>>>            fsparam_u32   ("nconnect",      Opt_nconnect),
>>>>>>            fsparam_u32   ("max_connect",   Opt_max_connect),
>>>>>>            fsparam_string("nfsvers",       Opt_vers),
>>>>>> -       fsparam_u32   ("port",          Opt_port),
>>>>>> +       fsparam_s32   ("port",          Opt_port),
>>>>>>            fsparam_flag_no("posix",        Opt_posix),
>>>>>>            fsparam_string("proto",         Opt_proto),
>>>>>>            fsparam_flag_no("rdirplus",     Opt_rdirplus),
>>>>>>
>>>>>>
>>>>> Why don't we just check for the ENOPARAM return value from
>>>>> fs_parse()?
>>>> In this case I think the return will be EINVAL.
>>> My point is that 'sloppy' is only supposed to work to suppress the
>>> error in the case where an option is not found by the parser. That
>>> corresponds to the error ENOPARAM.
>> Well, yes, and that's why ENOPARAM isn't returned and shouldn't be.
>>
>> And if the sloppy option is given it doesn't get to check the value
>>
>> of the option, it just returns success which isn't right.
>>
>>
>>>> I think that's a bit to general for this case.
>>>>
>>>> This seemed like the most sensible way to fix it.
>>>>
>>> Your patch works around just one symptom of the problem instead of
>>> addressing the root cause.
>>>
>> Ok, how do you recommend I fix this?
>>
> Maybe I'm missing something, but why not this?
>
> 8<--------------------------------
> diff --git a/fs/nfs/fs_context.c b/fs/nfs/fs_context.c
> index 9a16897e8dc6..8f1f9b4af89d 100644
> --- a/fs/nfs/fs_context.c
> +++ b/fs/nfs/fs_context.c
> @@ -484,7 +484,7 @@ static int nfs_fs_context_parse_param(struct
> fs_context *fc,
>   
>   	opt = fs_parse(fc, nfs_fs_parameters, param, &result);
>   	if (opt < 0)
> -		return ctx->sloppy ? 1 : opt;
> +		return (opt == -ENOPARAM && ctx->sloppy) ? 1 : opt;


Right but fs_parse() will return EINVAL in the case where a valid option

is used but its value is wrong such as where the value given is negative

but the param definition is unsigned (causing the EINVAL).

Of course this case is checked for and handled later in the NFS option

handling ...


There's also the question of option ordering which I haven't looked at

closely yet but might not be working properly.


Ian

>   
>   	if (fc->security)
>   		ctx->has_sec_mnt_opts = 1;
>