netdev - [PATCH net] net/smc: Remove validation of reserved bits in CLC Decline message

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Message-ID: <20250829102626.3271637-1-mjambigi@linux.ibm.com>
Date: Fri, 29 Aug 2025 12:26:26 +0200
From: Mahanta Jambigi <mjambigi@...ux.ibm.com>
To: andrew+netdev@...n.ch, davem@...emloft.net, edumazet@...gle.com,
        kuba@...nel.org, pabeni@...hat.com, alibuda@...ux.alibaba.com,
        dust.li@...ux.alibaba.com, sidraya@...ux.ibm.com, wenjia@...ux.ibm.com
Cc: pasic@...ux.ibm.com, horms@...nel.org, tonylu@...ux.alibaba.com,
        guwen@...ux.alibaba.com, netdev@...r.kernel.org,
        linux-s390@...r.kernel.org, linux-rdma@...r.kernel.org,
        Mahanta Jambigi <mjambigi@...ux.ibm.com>,
        Alexandra Winter <wintera@...ux.ibm.com>
Subject: [PATCH net] net/smc: Remove validation of reserved bits in CLC Decline message

Currently SMC code is validating the reserved bits while parsing the incoming
CLC decline message & when this validation fails, its treated as a protocol
error. As a result, the SMC connection is terminated instead of falling back to
TCP. As per RFC7609[1] specs we shouldn't be validating the reserved bits that
is part of CLC message. This patch fixes this issue.

CLC Decline message format can viewed here[2].

[1] https://datatracker.ietf.org/doc/html/rfc7609#page-92
[2] https://datatracker.ietf.org/doc/html/rfc7609#page-105

Fixes: 8ade200(net/smc: add v2 format of CLC decline message)

Signed-off-by: Mahanta Jambigi <mjambigi@...ux.ibm.com>
Reference-ID: LTC214332
Reviewed-by: Sidraya Jayagond <sidraya@...ux.ibm.com>
Reviewed-by: Alexandra Winter <wintera@...ux.ibm.com>

---
 net/smc/smc_clc.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/net/smc/smc_clc.c b/net/smc/smc_clc.c
index 5a4db151fe95..08be56dfb3f2 100644
--- a/net/smc/smc_clc.c
+++ b/net/smc/smc_clc.c
@@ -426,8 +426,6 @@ smc_clc_msg_decl_valid(struct smc_clc_msg_decline *dclc)
 {
 	struct smc_clc_msg_hdr *hdr = &dclc->hdr;
 
-	if (hdr->typev1 != SMC_TYPE_R && hdr->typev1 != SMC_TYPE_D)
-		return false;
 	if (hdr->version == SMC_V1) {
 		if (ntohs(hdr->length) != sizeof(struct smc_clc_msg_decline))
 			return false;
-- 
2.48.1