Re: [PATCHv3 net-next 2/4] sctp: implement sender-side procedures for SSN/TSN Reset Request Paramete

[Xin Long <lucien.xin@gmail.com>]

On Fri, Jan 20, 2017 at 6:02 AM, Marcelo Ricardo Leitner
<marcelo.leitner@gmail.com> wrote:
> On Fri, Jan 20, 2017 at 01:19:12AM +0800, Xin Long wrote:
>> This patch is to implement Sender-Side Procedures for the SSN/TSN
>> Reset Request Parameter descibed in rfc6525 section 5.1.4.
>>
>> It is also to add sockopt SCTP_RESET_ASSOC in rfc6525 section 6.3.3
>> for users.
>>
>> Signed-off-by: Xin Long <lucien.xin@gmail.com>
>> ---
>>  include/net/sctp/sctp.h   |  1 +
>>  include/uapi/linux/sctp.h |  1 +
>>  net/sctp/socket.c         | 29 +++++++++++++++++++++++++++++
>>  net/sctp/stream.c         | 33 +++++++++++++++++++++++++++++++++
>>  4 files changed, 64 insertions(+)
>>
>> diff --git a/include/net/sctp/sctp.h b/include/net/sctp/sctp.h
>> index 3cfd365b..b93820f 100644
>> --- a/include/net/sctp/sctp.h
>> +++ b/include/net/sctp/sctp.h
>> @@ -198,6 +198,7 @@ int sctp_offload_init(void);
>>   */
>>  int sctp_send_reset_streams(struct sctp_association *asoc,
>>                           struct sctp_reset_streams *params);
>> +int sctp_send_reset_assoc(struct sctp_association *asoc);
>>
>>  /*
>>   * Module global variables
>> diff --git a/include/uapi/linux/sctp.h b/include/uapi/linux/sctp.h
>> index 03c27ce..c0bd8c3 100644
>> --- a/include/uapi/linux/sctp.h
>> +++ b/include/uapi/linux/sctp.h
>> @@ -117,6 +117,7 @@ typedef __s32 sctp_assoc_t;
>>  #define SCTP_PR_ASSOC_STATUS 115
>>  #define SCTP_ENABLE_STREAM_RESET     118
>>  #define SCTP_RESET_STREAMS   119
>> +#define SCTP_RESET_ASSOC     120
>>
>>  /* PR-SCTP policies */
>>  #define SCTP_PR_SCTP_NONE    0x0000
>> diff --git a/net/sctp/socket.c b/net/sctp/socket.c
>> index bee4dd3..2c5c9ca 100644
>> --- a/net/sctp/socket.c
>> +++ b/net/sctp/socket.c
>> @@ -3812,6 +3812,32 @@ static int sctp_setsockopt_reset_streams(struct sock *sk,
>>       return retval;
>>  }
>>
>> +static int sctp_setsockopt_reset_assoc(struct sock *sk,
>> +                                    char __user *optval,
>> +                                    unsigned int optlen)
>> +{
>> +     struct sctp_association *asoc;
>> +     sctp_assoc_t associd;
>> +     int retval = -EINVAL;
>> +
>> +     if (optlen != sizeof(associd))
>> +             goto out;
>> +
>> +     if (copy_from_user(&associd, optval, optlen)) {
>> +             retval = -EFAULT;
>> +             goto out;
>> +     }
>> +
>> +     asoc = sctp_id2assoc(sk, associd);
>> +     if (!asoc)
>> +             goto out;
>> +
>> +     retval = sctp_send_reset_assoc(asoc);
>> +
>> +out:
>> +     return retval;
>> +}
>> +
>>  /* API 6.2 setsockopt(), getsockopt()
>>   *
>>   * Applications use setsockopt() and getsockopt() to set or retrieve
>> @@ -3984,6 +4010,9 @@ static int sctp_setsockopt(struct sock *sk, int level, int optname,
>>       case SCTP_RESET_STREAMS:
>>               retval = sctp_setsockopt_reset_streams(sk, optval, optlen);
>>               break;
>> +     case SCTP_RESET_ASSOC:
>> +             retval = sctp_setsockopt_reset_assoc(sk, optval, optlen);
>> +             break;
>>       default:
>>               retval = -ENOPROTOOPT;
>>               break;
>> diff --git a/net/sctp/stream.c b/net/sctp/stream.c
>> index 13d5e07..b368191 100644
>> --- a/net/sctp/stream.c
>> +++ b/net/sctp/stream.c
>> @@ -162,3 +162,36 @@ int sctp_send_reset_streams(struct sctp_association *asoc,
>>  out:
>>       return retval;
>>  }
>> +
>> +int sctp_send_reset_assoc(struct sctp_association *asoc)
>> +{
>> +     struct sctp_chunk *chunk = NULL;
>> +     int retval;
>> +     __u16 i;
>> +
>> +     if (!asoc->peer.reconf_capable ||
>> +         !(asoc->strreset_enable & SCTP_ENABLE_RESET_ASSOC_REQ))
>> +             return -ENOPROTOOPT;
>> +
>> +     if (asoc->strreset_outstanding)
>> +             return -EINPROGRESS;
>> +
>> +     chunk = sctp_make_strreset_tsnreq(asoc);
>> +     if (!chunk)
>> +             return -ENOMEM;
>> +
>
> Please add a comment here explaining that the for below is to block
> further xmit of data until this request is completed.
sure.

>
>> +     for (i = 0; i < asoc->stream->outcnt; i++)
>> +             asoc->stream->out[i].state = SCTP_STREAM_CLOSED;
>> +
>> +     asoc->strreset_outstanding = 1;
>> +     asoc->strreset_chunk = chunk;
>> +     sctp_chunk_hold(asoc->strreset_chunk);
>> +
>> +     retval = sctp_send_reconf(asoc, chunk);
>> +     if (retval) {
>> +             sctp_chunk_put(asoc->strreset_chunk);
>> +             asoc->strreset_chunk = NULL;
>
> If this happens, the asoc will get stuck, as strreset_outstanding is
> marked as 1, all streams are closed and no packet was even queued
> (I'm assuming so as you're dropping the reference on it).
you're right, I'm planning to move:
>> +     for (i = 0; i < asoc->stream->outcnt; i++)
>> +             asoc->stream->out[i].state = SCTP_STREAM_CLOSED;
>> +
>> +     asoc->strreset_outstanding = 1;

right after this check. so that it will do it only when
the reconf chunk is sent out.

>
>
>> +     }
>> +
>> +     return retval;
>> +}
>> --
>> 2.1.0
>>
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