From 01ae8969a9eed652fbd894faa5b31b1593079ed8 Mon Sep 17 00:00:00 2001 From: Rick Macklem Date: Tue, 30 Mar 2021 14:31:05 -0700 Subject: [PATCH] nfsd: do not implicitly bind the back channel for NFSv4.1/4.2 mounts The NFSv4.1 (and 4.2 on 13) server incorrectly binds a new TCP connection to the back channel when first used by an RPC with a Sequence op in it (almost all of them). RFC5661 specifies that only the fore channel should be bound. This was done because early clients (including FreeBSD) did not do the required BindConnectionToSession RPC. Unfortunately, this breaks the Linux client when the "nconnects" mount option is used, since the server may do a callback on the incorrect TCP connection. This patch converts the server behaviour to that required by the RFC. It also makes the server test/indicate failure of the back channel more aggressively. Until this patch is applied to the server, the "nconnects" mount option is not recommended for a Linux NFSv4.1/4.2 client mount to the FreeBSD server. Reported by: bcodding@redhat.com Tested by: bcodding@redhat.com PR: 254560 MFC after: 1 week --- sys/fs/nfsserver/nfs_nfsdstate.c | 33 ++++---------------------------- 1 file changed, 4 insertions(+), 29 deletions(-) diff --git a/sys/fs/nfsserver/nfs_nfsdstate.c b/sys/fs/nfsserver/nfs_nfsdstate.c index 1f6e8b7ef526..5ac37ed07cae 100644 --- a/sys/fs/nfsserver/nfs_nfsdstate.c +++ b/sys/fs/nfsserver/nfs_nfsdstate.c @@ -6209,7 +6209,6 @@ nfsrv_checksequence(struct nfsrv_descript *nd, uint32_t sequenceid, struct nfsdsession *sep; struct nfssessionhash *shp; int error; - SVCXPRT *savxprt; shp = NFSSESSIONHASH(nd->nd_sessionid); NFSLOCKSESSION(shp); @@ -6235,36 +6234,11 @@ nfsrv_checksequence(struct nfsrv_descript *nd, uint32_t sequenceid, nd->nd_maxreq = sep->sess_maxreq; nd->nd_maxresp = sep->sess_maxresp; - /* - * If this session handles the backchannel, save the nd_xprt for this - * RPC, since this is the one being used. - * RFC-5661 specifies that the fore channel will be implicitly - * bound by a Sequence operation. However, since some NFSv4.1 clients - * erroneously assumed that the back channel would be implicitly - * bound as well, do the implicit binding unless a - * BindConnectiontoSession has already been done on the session. - */ - savxprt = NULL; - if (sep->sess_clp->lc_req.nr_client != NULL && - sep->sess_cbsess.nfsess_xprt != nd->nd_xprt && - (sep->sess_crflags & NFSV4CRSESS_CONNBACKCHAN) != 0 && - (sep->sess_clp->lc_flags & LCL_DONEBINDCONN) == 0) { - NFSD_DEBUG(2, - "nfsrv_checksequence: implicit back channel bind\n"); - savxprt = sep->sess_cbsess.nfsess_xprt; - SVC_ACQUIRE(nd->nd_xprt); - nd->nd_xprt->xp_p2 = - sep->sess_clp->lc_req.nr_client->cl_private; - nd->nd_xprt->xp_idletimeout = 0; /* Disable timeout. */ - sep->sess_cbsess.nfsess_xprt = nd->nd_xprt; - } - *sflagsp = 0; - if (sep->sess_clp->lc_req.nr_client == NULL) + if (sep->sess_clp->lc_req.nr_client == NULL || + (sep->sess_clp->lc_flags & LCL_CBDOWN) != 0) *sflagsp |= NFSV4SEQ_CBPATHDOWN; NFSUNLOCKSESSION(shp); - if (savxprt != NULL) - SVC_RELEASE(savxprt); if (error == NFSERR_EXPIRED) { *sflagsp |= NFSV4SEQ_EXPIREDALLSTATEREVOKED; error = 0; @@ -6464,7 +6438,8 @@ nfsrv_bindconnsess(struct nfsrv_descript *nd, uint8_t *sessionid, int *foreaftp) nd->nd_xprt->xp_idletimeout = 0; sep->sess_cbsess.nfsess_xprt = nd->nd_xprt; sep->sess_crflags |= NFSV4CRSESS_CONNBACKCHAN; - clp->lc_flags |= LCL_DONEBINDCONN; + clp->lc_flags |= LCL_DONEBINDCONN | + LCL_NEEDSCBNULL; if (*foreaftp == NFSCDFS4_BACK) *foreaftp = NFSCDFS4_BACK; else