Commit c86d8613 authored Feb 02, 2022 by Dmitry V. Levin Committed by Jakub Kicinski Feb 02, 2022

Partially revert "net/smc: Add netlink net namespace support"



The change of sizeof(struct smc_diag_linkinfo) by commit 79d39fc5
("net/smc: Add netlink net namespace support") introduced an ABI
regression: since struct smc_diag_lgrinfo contains an object of
type "struct smc_diag_linkinfo", offset of all subsequent members
of struct smc_diag_lgrinfo was changed by that change.

As result, applications compiled with the old version
of struct smc_diag_linkinfo will receive garbage in
struct smc_diag_lgrinfo.role if the kernel implements
this new version of struct smc_diag_linkinfo.

Fix this regression by reverting the part of commit 79d39fc5 that
changes struct smc_diag_linkinfo.  After all, there is SMC_GEN_NETLINK
interface which is good enough, so there is probably no need to touch
the smc_diag ABI in the first place.

Fixes: 79d39fc5 ("net/smc: Add netlink net namespace support")
Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
Reviewed-by: Karsten Graul <kgraul@linux.ibm.com>
Link: https://lore.kernel.org/r/20220202030904.GA9742@altlinux.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>

parent c8ff576e

include/uapi/linux/smc_diag.h

+5 −6

Original line number	Original line	Diff line number	Diff line
	@@ -89,7 +89,6 @@ struct smc_diag_linkinfo {
	__u8 ibport; /* RDMA device port number */		__u8 ibport; /* RDMA device port number */
	__u8 gid[40]; /* local GID */		__u8 gid[40]; /* local GID */
	__u8 peer_gid[40]; /* peer GID */		__u8 peer_gid[40]; /* peer GID */
	__aligned_u64 net_cookie; /* RDMA device net namespace */
	};		};

	struct smc_diag_lgrinfo {		struct smc_diag_lgrinfo {

net/smc/smc_diag.c

+0 −2

Original line number	Original line	Diff line number	Diff line
	@@ -146,13 +146,11 @@ static int __smc_diag_dump(struct sock sk, struct sk_buff skb,
	(req->diag_ext & (1 << (SMC_DIAG_LGRINFO - 1))) &&		(req->diag_ext & (1 << (SMC_DIAG_LGRINFO - 1))) &&
	!list_empty(&smc->conn.lgr->list)) {		!list_empty(&smc->conn.lgr->list)) {
	struct smc_link *link = smc->conn.lnk;		struct smc_link *link = smc->conn.lnk;
	struct net *net = read_pnet(&link->smcibdev->ibdev->coredev.rdma_net);

	struct smc_diag_lgrinfo linfo = {		struct smc_diag_lgrinfo linfo = {
	.role = smc->conn.lgr->role,		.role = smc->conn.lgr->role,
	.lnk[0].ibport = link->ibport,		.lnk[0].ibport = link->ibport,
	.lnk[0].link_id = link->link_id,		.lnk[0].link_id = link->link_id,
	.lnk[0].net_cookie = net->net_cookie,
	};		};

	memcpy(linfo.lnk[0].ibname,		memcpy(linfo.lnk[0].ibname,