Re: [PATCH IB/core 2/2] IB/cm: Send authentic pkey in REQ msg and check eligibility of the pkeys

From: Hal Rosenstock
Date: Fri May 11 2018 - 08:51:26 EST

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On 5/11/2018 6:55 AM, HÃkon Bugge wrote:
>
>
>> On 10 May 2018, at 18:54, Hal Rosenstock <hal@xxxxxxxxxxxxxxxxxx> wrote:
>>
>> On 5/10/2018 11:16 AM, HÃkon Bugge wrote:
>>>
>>>
>>>> On 10 May 2018, at 16:01, Hal Rosenstock <hal@xxxxxxxxxxxxxxxxxx> wrote:
>>>>
>>>> On 5/10/2018 5:16 AM, HÃkon Bugge wrote:
>>>>>
>>>>>
>>>>>> On 9 May 2018, at 13:28, Hal Rosenstock <hal@xxxxxxxxxxxxxxxxxx> wrote:
>>>>>>
>>>>>> On 5/9/2018 5:30 AM, HÃkon Bugge wrote:
>>>>>>> There is no point in using RDMA CM to establish a connection between
>>>>>>> two QPs that cannot possible communicate. Particularly, if both the
>>>>>>> active and passive side use limited pkeys, they are not able to
>>>>>>> communicate.
>>>>>>>
>>>>>>> In order to detect this situation, the authentic pkey is used in the
>>>>>>> CM REQ message. The authentic pkey is the one that the HCA inserts
>>>>>>> into the BTH in the IB packets.
>>>>>>>
>>>>>>> When the passive side receives the REQ, commit ("ib_core: A full pkey
>>>>>>> is required to match a limited one") ensures that
>>>>>>> ib_find_matched_cached_pkey() fails unless at least one of the pkeys
>>>>>>> compared has the full-member bit.
>>>>>>>
>>>>>>> In the limited-to-limited case, this will prohibit the connection to
>>>>>>> be formed, and thus, Pkey Violation Traps will not be sent to the SM.
>>>>>>>
>>>>>>> Signed-off-by: HÃkon Bugge <haakon.bugge@xxxxxxxxxx>
>>>>>>> ---
>>>>>>> drivers/infiniband/core/cm.c | 39 ++++++++++++++++++++++++++++++++-------
>>>>>>> include/rdma/ib_cm.h | 4 +++-
>>>>>>> 2 files changed, 35 insertions(+), 8 deletions(-)
>>>>>>>
>>>>>>> diff --git a/drivers/infiniband/core/cm.c b/drivers/infiniband/core/cm.c
>>>>>>> index a92e1a5c202b..52ed51d5bd2a 100644
>>>>>>> --- a/drivers/infiniband/core/cm.c
>>>>>>> +++ b/drivers/infiniband/core/cm.c
>>>>>>> @@ -3,6 +3,7 @@
>>>>>>> * Copyright (c) 2004 Topspin Corporation. All rights reserved.
>>>>>>> * Copyright (c) 2004, 2005 Voltaire Corporation. All rights reserved.
>>>>>>> * Copyright (c) 2005 Sun Microsystems, Inc. All rights reserved.
>>>>>>> + * Copyright (c) 2018 Oracle and/or its affiliates. All rights reserved.
>>>>>>> *
>>>>>>> * This software is available to you under a choice of one of two
>>>>>>> * licenses. You may choose to be licensed under the terms of the GNU
>>>>>>> @@ -91,6 +92,7 @@ static const char * const ibcm_rej_reason_strs[] = {
>>>>>>> [IB_CM_REJ_INVALID_CLASS_VERSION] = "invalid class version",
>>>>>>> [IB_CM_REJ_INVALID_FLOW_LABEL] = "invalid flow label",
>>>>>>> [IB_CM_REJ_INVALID_ALT_FLOW_LABEL] = "invalid alt flow label",
>>>>>>> + [IB_CM_REJ_INVALID_PKEY] = "invalid PKey",
>>>>>>
>>>>>> If this patch goes ahead, IBA spec for CM should be updated to include this.
>>>>>
>>>>> Sure, I see:
>>>>>
>>>>> 33 Invalid Alternate Flow Label
>>>>>
>>>>> as the latest in the spec.
>>>>
>>>> This appears to be an implementation rather than architectural issue. If
>>>> there is limited <-> limited CM, then the MAD would never get up to the
>>>> CM layer as it would be filtered by end port pkey enforcement. This is
>>>> only needed to protect against current code which can send on the full
>>>> rather than limited pkey (in BTH), right ?
>>>
>>> We are talking about two things here. The PKey in the BTH and the PKey in the CM REQ payload. They differ.
>>
>> Yes, I understand the difference between the 2 potentially different PKeys.
>>
>>> I am out of office, but if my memory serves me correct, the PKey in the BTH in the MAD packet will be the default PKey.
>>
>> MADs are sent on reversible paths (13.5.4.1) where the response can be
>> constructed from only header info in the request. BTH:pkey doesn't
>> __have to be__ the default pkey. It just needs to be a common/shared
>> pkey between the source/destination pair.
>>
>> For example, there are some configurations where the port is only a
>> limited member of the default partition (and full member of other non
>> default partition(s)).
>>
>> There are also configurations where the port is both full and limited
>> member on one or more partition(s). This is the allow_both_pkeys TRUE
>> case for OpenSM which also uses the 'both' syntax in the partitions
>> config file. This appears to be the case to which you are referring.
>>
>> CM MAD could be sent on default partition but that may not work if both
>> source and dest are only limited members of the default partition.
>>
>> CM MAD could be sent on any common/shared pkey between the
>> source/destination ports.
>>
>>> Further, we have per IBTA:
>>>
>>> C10-132: Packets sent to the General Service Interface QP (QP1) shall be accepted if the P_Key in the packet matches any valid P_Key in the P_Key Table of the port on which the packet arrived. Matching is defined in 10.9.3 Partition Key Matching.
>>>
>>> So, by architecture, the MAD arrives
>> In the case of port being both full and limited member of the same
>> partition on which CM MAD comes in on (as defined by pkey in BTH).
>>
>> I was talking about limited <-> limited CM and didn't realize you were
>> talking about the âboth' case.
>
> OK. So we agree that for the most typical cases, where the BTH.PKey is the default one, the MAD will be received and not trapped by the PKey check.
>
>>>>
>>>>
>>>>>>
>>>>>>> };
>>>>>>>
>>>>>>> const char *__attribute_const__ ibcm_reject_msg(int reason)
>>>>>>> @@ -518,8 +520,8 @@ static int cm_init_av_by_path(struct sa_path_rec *path, struct cm_av *av,
>>>>>>> return -EINVAL;
>>>>>>> cm_dev = port->cm_dev;
>>>>>>>
>>>>>>> - ret = ib_find_cached_pkey(cm_dev->ib_device, port->port_num,
>>>>>>> - be16_to_cpu(path->pkey), &av->pkey_index);
>>>>>>> + ret = ib_find_matched_cached_pkey(cm_dev->ib_device, port->port_num,
>>>>>>> + be16_to_cpu(path->pkey), &av->pkey_index);

This routine is shared by LAP send/rcvd and SIDR send. Is this change
the correct thing to do there as well ? Were LAP and SIDR tested ?

>>>>>>> if (ret)
>>>>>>> return ret;
>>>>>>>
>>>>>>> @@ -1241,7 +1243,7 @@ static void cm_format_req(struct cm_req_msg *req_msg,
>>>>>>> cm_req_set_starting_psn(req_msg, cpu_to_be32(param->starting_psn));
>>>>>>> cm_req_set_local_resp_timeout(req_msg,
>>>>>>> param->local_cm_response_timeout);
>>>>>>> - req_msg->pkey = param->primary_path->pkey;
>>>>>>> + req_msg->pkey = cpu_to_be16(cm_id_priv->pkey);
>>>>>>> cm_req_set_path_mtu(req_msg, param->primary_path->mtu);
>>>>>>> cm_req_set_max_cm_retries(req_msg, param->max_cm_retries);
>>>>>>>
>>>>>>> @@ -1396,7 +1398,23 @@ int ib_send_cm_req(struct ib_cm_id *cm_id,
>>>>>>> cm_id_priv->responder_resources = param->responder_resources;
>>>>>>> cm_id_priv->retry_count = param->retry_count;
>>>>>>> cm_id_priv->path_mtu = param->primary_path->mtu;
>>>>>>> - cm_id_priv->pkey = param->primary_path->pkey;
>>>>>>> +
>>>>>>> + /*
>>>>>>> + * We want to send the pkey used in the BTH in packets
>>>>>>> + * sent. This, in order for the passive side to determine if
>>>>>>> + * communication is permitted by the respective pkeys.
>>>>>>> + *
>>>>>>> + * The pkey in the paths are derived from the MGID, which has
>>>>>>> + * the full membership bit set. Hence, we retrieve the pkey by
>>>>>>> + * using the address vector's pkey_index.
>>>>>>
>>>>>> The paths usually come from the SM and I don't expect SM to provide path
>>>>>> between ports of only limited members of partition.
>>>>>
>>>>> In my case, it does.
>>>>
>>>> Which OpenSM flavor are you talking about (upstream, MLNX, or other) ?
>>>
>>> I guess other is the right term, as its Oracleâs flavour, 3.2.6_20170609.
>>
>> I'll check upstream OpenSM when I get a chance to see if same problem
>> exists. Oracle OpenSM forked from upstream long time ago and not sure
>> how similar the path record code is. There were various impacts for the
>> shared port virtualization (for CX-3) in terms of adding the ability to
>> allow both pkeys.
>
> I just had a chat with Line H. here in Oracle. She confirms that Oracleâs SM and the upstream one act similar in this matter.

To be sure, I will double check this with upstream when I get a few
cycles to do this.

> Further, using shared port virtualization, OpenSM will adhere to the physical ports only, and doesnât even know the PKey assignments to the VFs assigned the VMs.

Right; with the shared port virtualization, the SM only knows about the
pport (physical port) partitioning whereas with the newer virtualization
annex there is also the vport (VF) partitioning in addition to the pport
partitioning. This has an impact on the paths that can be provided.

>
>>>> What is OpenSM version string ? Is allow_both_pkeys TRUE or FALSE ?
>>>
>>> The ports do have both limited and full memberships, and the partitions.conf file contains both âlimitedâ, âbothâ, and the âfullâ keywords.
>>>
>>>>>> Default ACM provider
>>>>>> forms path from multicast group parameters including pkey. Is that the
>>>>>> scenario of concern ?
>>>>>
>>>>> Also RDMA CM does that. Do an ibdump of a CM REQ message sent from a limited port, and you will see the PKey is the full member in the CM REQ msg.
>>>>
>>>> Not exactly sure what you mean by RDMA CM does this as there are a
>>>> number of different ways to use RDMA CM.
>>>
>>> I am talking specifically about the CM REQ message. For example, if you run an IB-UV test program and specifies that RDMA CM should be used for connection management. Or it could be kernel ULPs. My point is that the pkey field in the CM REQ message (i.e. not the one in the BTH) is always the full one, even though the port uses the limited one.
>>
>> When you write "port uses limited one", you mean BTH:pkey is limited
>> member but REQ:pkey is full member, right ?
>
> Yes, but the BTH:pkey is, as stated above most often the default pkey (limited or full), whilst REQ:pkey is a designated, limited pkey.

FWIW I think the comment "The pkey in the paths are derived from the
MGID" can be improved as this is one use case and is not the most common
one.

>>>> Are you referring to using
>>>> IPoIB for address resolution ? Another way is for a path record to be
>>>> passed in from user space and there is no control over itâs contents.
>>>
>>> I did not bring up the path record or address resolution issue ;-)
>>
>> You mentioned that "The pkey in the paths are derived from the MGID" and
>> brought this issue up in my thinking about this issue.
>
> Yes, just to inform why it is full - when it shouldnât be.
>
>>> But I guess you are alluding to the limited-to-limited case should 1) not have been able to perform address resolution and/or 2) the path record should not have been returned. I agree to both 1) and 2).
>>>
>>> But if both 1) and 2) succeeds, this patch series is a last resort to stop the connection to be established and avoid pkey trap violation traps being sent.
>>>
>>>> At a minimum, I think the comment mentioning MGID should be clarified.
>>>
>>> Is the question if an MC group attached by a limited port will include other limited ports or only full member ports?
>>>
>>> With the OpenSM I am running, the MC group contains limited members.
>>
>> That is problematic as any sending to MC group by limited members will
>> cause pkey violation traps to SM.
>
> Sure, agree, but a separate issue from this series which handles the unicast case.
>
>>>>>> If so, I still don't fully understand the scenario
>>>>>> because limited members are not supposed to be part of a multicast
>>>>>> group. There was some work started to extend this for client/server
>>>>>> model but it was never completed. However, there may be hole(s) in
>>>>>> various components of implementation which open(s) this door.
>>>>>
>>>>> I view OpenSM not returning a valid path between two limited members an orthogonal issue, as OpenSM is another component.
>>>>
>>>> Agreed. I think that there are other components too...
>>>>
>>>>> I think the CM REQ message should contain the correct PKey (fixed by this patch series).
>>>>>
>>>>> And in the event the passive side being a limited member and receives a CM REQ with a limited PKey, that connection should not be formed (fixed by this patch series).
>>>> This is the backward compatibility for the current behavior on the
>>>> active side so that REQ gets rejected rather than accepted, right ?
>>>
>>> Not sure about the backwards compatibility part, but I certainly agree to the rest. Put it another way, when the MAD payloadâs pkey is limited in the CM REQ, and there is only a limited matching key in the pkey cache, a REJ is sent back.
>>
>> Understood.
>>
>>>> In general, the approach used when there is pkey mismatch is to silently
>>>> drop packet rather than respond which causes a timeout on the requester
>>>> side. In this specific case, Iâm not sure which approach is better.
>>>
>>> It is not silently dropped when the port supports pkey trap messages. Then a trap message is sent to the OpenSM.
>>
>> I was only talking about the requester-responder part. Yes, pkey
>> security trap would go to SM.
>>
>> As I wrote, I'm not sure which is preferable: to explictly reject as
>> this patch proposes or just silently drop and penalize requester.
>
> Since the infrastructure is in place, i.e., the REJ reasons, my view is that an explicit REJ with a distinct reason is the most obvious.

The downsides are that it reveals info that perhaps should not be
revealed and allows the requestor to rerequest sooner. In some
scenarios, that could cause DoS attack on the responder (server).

-- Hal

>
> Thxs, HÃkon
>
>>
>> -- Hal
>>
>>>> Also, is there a similar issue with SIDR_REQ ?
>>>
>>> Good point, most probaly!
>>>
>>>> Read me correct, I am also in favour of fixing the OpenSM to not return a valid (but useless) path record in this case.
>>>>
>>>> Understood and agreed.
>>>
>>>
>>> Thxs, HÃkon
>>>
>>>>
>>>> -- Hal
>>>>
>>>>>
>>>>> Thxs, HÃkon
>>>>>
>>>>>
>>>>>>
>>>>>> -- Hal
>>>>>>
>>>>>>> + */
>>>>>>> + ret = ib_get_cached_pkey(cm_id_priv->id.device,
>>>>>>> + cm_id_priv->av.port->port_num,
>>>>>>> + cm_id_priv->av.pkey_index,
>>>>>>> + &cm_id_priv->pkey);
>>>>>>> + if (ret)
>>>>>>> + goto error1;
>>>>>>> +
>>>>>>> cm_id_priv->qp_type = param->qp_type;
>>>>>>>
>>>>>>> ret = cm_alloc_msg(cm_id_priv, &cm_id_priv->msg);
>>>>>>> @@ -1956,16 +1974,19 @@ static int cm_req_handler(struct cm_work *work)
>>>>>>> cm_id_priv);
>>>>>>> if (ret) {
>>>>>>> int err;
>>>>>>> + int rej_reason = (ret == -ENOENT ?
>>>>>>> + IB_CM_REJ_INVALID_PKEY :
>>>>>>> + IB_CM_REJ_INVALID_GID);
>>>>>>>
>>>>>>> err = ib_get_cached_gid(work->port->cm_dev->ib_device,
>>>>>>> work->port->port_num, 0,
>>>>>>> &work->path[0].sgid,
>>>>>>> NULL);
>>>>>>> if (err)
>>>>>>> - ib_send_cm_rej(cm_id, IB_CM_REJ_INVALID_GID,
>>>>>>> + ib_send_cm_rej(cm_id, rej_reason,
>>>>>>> NULL, 0, NULL, 0);
>>>>>>> else
>>>>>>> - ib_send_cm_rej(cm_id, IB_CM_REJ_INVALID_GID,
>>>>>>> + ib_send_cm_rej(cm_id, rej_reason,
>>>>>>> &work->path[0].sgid,
>>>>>>> sizeof(work->path[0].sgid),
>>>>>>> NULL, 0);
>>>>>>> @@ -1975,7 +1996,11 @@ static int cm_req_handler(struct cm_work *work)
>>>>>>> ret = cm_init_av_by_path(&work->path[1], &cm_id_priv->alt_av,
>>>>>>> cm_id_priv);
>>>>>>> if (ret) {
>>>>>>> - ib_send_cm_rej(cm_id, IB_CM_REJ_INVALID_ALT_GID,
>>>>>>> + int rej_reason = (ret == -ENOENT ?
>>>>>>> + IB_CM_REJ_INVALID_PKEY :
>>>>>>> + IB_CM_REJ_INVALID_ALT_GID);
>>>>>>> +
>>>>>>> + ib_send_cm_rej(cm_id, rej_reason,
>>>>>>> &work->path[0].sgid,
>>>>>>> sizeof(work->path[0].sgid), NULL, 0);
>>>>>>> goto rejected;
>>>>>>> diff --git a/include/rdma/ib_cm.h b/include/rdma/ib_cm.h
>>>>>>> index 7979cb04f529..56b62303946a 100644
>>>>>>> --- a/include/rdma/ib_cm.h
>>>>>>> +++ b/include/rdma/ib_cm.h
>>>>>>> @@ -3,6 +3,7 @@
>>>>>>> * Copyright (c) 2004 Topspin Corporation. All rights reserved.
>>>>>>> * Copyright (c) 2004 Voltaire Corporation. All rights reserved.
>>>>>>> * Copyright (c) 2005 Sun Microsystems, Inc. All rights reserved.
>>>>>>> + * Copyright (c) 2018 Oracle and/or its affiliates. All rights reserved.
>>>>>>> *
>>>>>>> * This software is available to you under a choice of one of two
>>>>>>> * licenses. You may choose to be licensed under the terms of the GNU
>>>>>>> @@ -183,7 +184,8 @@ enum ib_cm_rej_reason {
>>>>>>> IB_CM_REJ_DUPLICATE_LOCAL_COMM_ID = 30,
>>>>>>> IB_CM_REJ_INVALID_CLASS_VERSION = 31,
>>>>>>> IB_CM_REJ_INVALID_FLOW_LABEL = 32,
>>>>>>> - IB_CM_REJ_INVALID_ALT_FLOW_LABEL = 33
>>>>>>> + IB_CM_REJ_INVALID_ALT_FLOW_LABEL = 33,
>>>>>>> + IB_CM_REJ_INVALID_PKEY = 34,
>>>>>>> };
>>>>>>>
>>>>>>> struct ib_cm_rej_event_param {
>>>>>>>
>>>>>> --
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>>>>>> the body of a message to majordomo@xxxxxxxxxxxxxxx
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>>>>>
>>>>>
>>>> --
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>>>
>>>
>> --
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>
>

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