netdev - Re: [PATCH net-next 3/8] sctp: implement validate_ftsn for sctp_stream

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Date:   Tue, 12 Dec 2017 21:31:36 +0800
From:   Xin Long <lucien.xin@...il.com>
To:     Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
Cc:     network dev <netdev@...r.kernel.org>, linux-sctp@...r.kernel.org,
        Neil Horman <nhorman@...driver.com>,
        davem <davem@...emloft.net>
Subject: Re: [PATCH net-next 3/8] sctp: implement validate_ftsn for sctp_stream_interleave

On Tue, Dec 12, 2017 at 9:18 PM, Marcelo Ricardo Leitner
<marcelo.leitner@...il.com> wrote:
> On Tue, Dec 12, 2017 at 05:25:54PM +0800, Xin Long wrote:
> ...
>> --- a/net/sctp/sm_statetable.c
>> +++ b/net/sctp/sm_statetable.c
>> @@ -992,7 +992,8 @@ static const struct sctp_sm_table_entry *sctp_chunk_event_lookup(
>>               return &chunk_event_table[cid][state];
>>
>>       if (net->sctp.prsctp_enable) {
>> -             if (cid == SCTP_CID_FWD_TSN)
>> +             if (cid == SCTP_CID_FWD_TSN ||
>> +                 (net->sctp.intl_enable && cid == SCTP_CID_I_FWD_TSN))
>
> We don't really need to check intl_enable here, do we?
We think net->sctp.xxx_enable as a main switch here,
that means it only accepts SCTP_CID_I_FWD_TSN
when this switch is open.

As for the check in validate_ftsn(), it follows the RFC checking
on asoc's intl_enable.

does it make sense from this perspective ?



> Because a) it should actually look like:
> -               if (cid == SCTP_CID_FWD_TSN)
> +               if ((!net->sctp.intl_enable && cid == SCTP_CID_FWD_TSN) ||
> +                   (net->sctp.intl_enable && cid == SCTP_CID_I_FWD_TSN))
> but b) we will validate the chunk format/feature later with
> validate_ftsn(), similarly to what happens with data chunks, so it
> seems the check on intl_enable here is not necessary.
>
> Same happens with data chunks, btw.
>
>>                       return &prsctp_chunk_event_table[0][state];
>>       }
>>
>> diff --git a/net/sctp/stream_interleave.c b/net/sctp/stream_interleave.c
>> index 2ead372..cc4a5e3 100644
>> --- a/net/sctp/stream_interleave.c
>> +++ b/net/sctp/stream_interleave.c
>> @@ -1153,8 +1153,49 @@ static void sctp_generate_iftsn(struct sctp_outq *q, __u32 ctsn)
>>       }
>>  }
>>
>> +#define _sctp_walk_ifwdtsn(pos, chunk, end) \
>> +     for (pos = chunk->subh.ifwdtsn_hdr->skip; \
>> +          (void *)pos < (void *)chunk->subh.ifwdtsn_hdr->skip + (end); pos++)
>> +
>> +#define sctp_walk_ifwdtsn(pos, ch) \
>> +     _sctp_walk_ifwdtsn((pos), (ch), ntohs((ch)->chunk_hdr->length) - \
>> +                                     sizeof(struct sctp_ifwdtsn_chunk))
>> +
>> +static bool sctp_validate_fwdtsn(struct sctp_chunk *chunk)
>> +{
>> +     struct sctp_fwdtsn_skip *skip;
>> +     __u16 incnt;
>> +
>> +     if (chunk->chunk_hdr->type != SCTP_CID_FWD_TSN)
>> +             return false;
>> +
>> +     incnt = chunk->asoc->stream.incnt;
>> +     sctp_walk_fwdtsn(skip, chunk)
>> +             if (ntohs(skip->stream) >= incnt)
>> +                     return false;
>> +
>> +     return true;
>> +}
>> +
>> +static bool sctp_validate_iftsn(struct sctp_chunk *chunk)
>> +{
>> +     struct sctp_ifwdtsn_skip *skip;
>> +     __u16 incnt;
>> +
>> +     if (chunk->chunk_hdr->type != SCTP_CID_I_FWD_TSN)
>> +             return false;
>> +
>> +     incnt = chunk->asoc->stream.incnt;
>> +     sctp_walk_ifwdtsn(skip, chunk)
>> +             if (ntohs(skip->stream) >= incnt)
>> +                     return false;
>> +
>> +     return true;
>> +}
>> +
>>  static struct sctp_stream_interleave sctp_stream_interleave_0 = {
>>       .data_chunk_len         = sizeof(struct sctp_data_chunk),
>> +     .ftsn_chunk_len         = sizeof(struct sctp_fwdtsn_chunk),
>>       /* DATA process functions */
>>       .make_datafrag          = sctp_make_datafrag_empty,
>>       .assign_number          = sctp_chunk_assign_ssn,
>> @@ -1166,10 +1207,12 @@ static struct sctp_stream_interleave sctp_stream_interleave_0 = {
>>       .abort_pd               = sctp_ulpq_abort_pd,
>>       /* FORWARD-TSN process functions */
>>       .generate_ftsn          = sctp_generate_fwdtsn,
>> +     .validate_ftsn          = sctp_validate_fwdtsn,
>>  };
>>
>>  static struct sctp_stream_interleave sctp_stream_interleave_1 = {
>>       .data_chunk_len         = sizeof(struct sctp_idata_chunk),
>> +     .ftsn_chunk_len         = sizeof(struct sctp_ifwdtsn_chunk),
>>       /* I-DATA process functions */
>>       .make_datafrag          = sctp_make_idatafrag_empty,
>>       .assign_number          = sctp_chunk_assign_mid,
>> @@ -1181,6 +1224,7 @@ static struct sctp_stream_interleave sctp_stream_interleave_1 = {
>>       .abort_pd               = sctp_intl_abort_pd,
>>       /* I-FORWARD-TSN process functions */
>>       .generate_ftsn          = sctp_generate_iftsn,
>> +     .validate_ftsn          = sctp_validate_iftsn,
>>  };
>>
>>  void sctp_stream_interleave_init(struct sctp_stream *stream)
>> --
>> 2.1.0
>>
>> --
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