On 8/1/2019 6:56 AM, Bernard Metzler wrote:
-----"Krishnamraju Eraparaju" <krishna2@xxxxxxxxxxx> wrote: -----To: jgg@xxxxxxxx, bmt@xxxxxxxxxxxxxx From: "Krishnamraju Eraparaju" <krishna2@xxxxxxxxxxx> Date: 07/31/2019 12:34PM Cc: linux-rdma@xxxxxxxxxxxxxxx, bharat@xxxxxxxxxxx, nirranjan@xxxxxxxxxxx, krishn2@xxxxxxxxxxx, "Krishnamraju Eraparaju" <krishna2@xxxxxxxxxxx> Subject: [EXTERNAL] [PATCH for-rc] siw: MPA Reply handler tries to read beyond MPA message while processing MPA Reply, SIW driver is trying to read extra 4 bytes than what peer has advertised as private data length. If a FPDU data is received before even siw_recv_mpa_rr() completed reading MPA reply, then ksock_recv() in siw_recv_mpa_rr() could also read FPDU, if "size" is larger than advertised MPA reply length. 501 static int siw_recv_mpa_rr(struct siw_cep *cep) 502 { ............. 572 573 if (rcvd > to_rcv) 574 return -EPROTO; <----- Failure here Looks like the intention here is to throw an ERROR if the received data is more than the total private data length advertised by the peer. But reading beyond MPA message causes siw_cm to generate RDMA_CM_EVENT_CONNECT_ERROR event when TCP socket recv buffer is already queued with FPDU messages. Hence, this function should only read upto private data length. Signed-off-by: Krishnamraju Eraparaju <krishna2@xxxxxxxxxxx> --- drivers/infiniband/sw/siw/siw_cm.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/infiniband/sw/siw/siw_cm.c b/drivers/infiniband/sw/siw/siw_cm.c index a7cde98e73e8..8dc8cea2566c 100644 --- a/drivers/infiniband/sw/siw/siw_cm.c +++ b/drivers/infiniband/sw/siw/siw_cm.c @@ -559,13 +559,13 @@ static int siw_recv_mpa_rr(struct siw_cep *cep) * A private data buffer gets allocated if hdr->params.pd_len != 0. */ if (!cep->mpa.pdata) { - cep->mpa.pdata = kmalloc(pd_len + 4, GFP_KERNEL); + cep->mpa.pdata = kmalloc(pd_len, GFP_KERNEL); if (!cep->mpa.pdata) return -ENOMEM; } rcvd = ksock_recv( s, cep->mpa.pdata + cep->mpa.bytes_rcvd - sizeof(struct mpa_rr), - to_rcv + 4, MSG_DONTWAIT); + to_rcv, MSG_DONTWAIT); if (rcvd < 0) return rcvd; -- 2.23.0.rc0The intention of this code is to make sure the peer does not violates the MPA handshake rules. The initiator MUST NOT send extra data after its MPA request and before receiving the MPA reply.
I think this is true only for MPA v2. With MPA v1, the initiator can begin sending immediately (before receiving the MPA reply), because there is no actual negotiation at the MPA layer. With MPA v2, the negotiation exchange is required because the type of the following message is predicated by the "Enhanced mode" a|b|c|d flags present in the first 32 bits of the private data buffer. So, it seems to me that additional logic is needed here to determine the MPA version, before sniffing additional octets from the incoming stream? Tom.
So, for the MPA request case, this code is needed to check for protocol correctness. You are right for the MPA reply case - if we are _not_ in peer2peer mode, the peer can immediately start sending data in RDMA mode after its MPA Reply. So we shall add appropriate code to be more specific For an error, we are (1) processing an MPA Request, OR (2) processing an MPA Reply AND we are not expected to send an initial READ/WRITE/Send as negotiated with the peer (peer2peer mode MPA handshake). Just removing this check would make siw more permissive, but to a point where peer MPA protocol errors are tolerated. I am not in favor of that level of forgiveness. If possible, please provide an appropriate patch or (if it causes current issues with another peer iWarp implementation) just run in MPA peer2peer mode, where the current check is appropriate. Otherwise, I would provide an appropriate fix by Monday (I am still out of office this week). Many thanks and best regards, Bernard.
