[RFC PATCH 1/6] NFSD: Handle @rqstp == NULL in check_nfsd_access()

[cel@kernel.org]

From: NeilBrown <neilb@suse.de>

LOCALIO-initiated open operations are not running in an nfsd thread
and thus do not have an associated svc_rqst context.

Signed-off-by: NeilBrown <neilb@suse.de>
Co-developed-by: Mike Snitzer <snitzer@kernel.org>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 fs/nfsd/export.c | 29 ++++++++++++++++++++++++-----
 1 file changed, 24 insertions(+), 5 deletions(-)

diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c
index 7bb4f2075ac5..46a4d989c850 100644
--- a/fs/nfsd/export.c
+++ b/fs/nfsd/export.c
@@ -1074,10 +1074,29 @@ static struct svc_export *exp_find(struct cache_detail *cd,
 	return exp;
 }
 
+/**
+ * check_nfsd_access - check if access to export is allowed.
+ * @exp: svc_export that is being accessed.
+ * @rqstp: svc_rqst attempting to access @exp (will be NULL for LOCALIO).
+ *
+ * Return values:
+ *   %nfs_ok if access is granted, or
+ *   %nfserr_wrongsec if access is denied
+ */
 __be32 check_nfsd_access(struct svc_export *exp, struct svc_rqst *rqstp)
 {
 	struct exp_flavor_info *f, *end = exp->ex_flavors + exp->ex_nflavors;
-	struct svc_xprt *xprt = rqstp->rq_xprt;
+	struct svc_xprt *xprt;
+
+	/*
+	 * The target use case for rqstp being NULL is LOCALIO, which
+	 * currently only supports AUTH_UNIX. The behavior for LOCALIO
+	 * is therefore the same as the AUTH_UNIX check below.
+	 */
+	if (!rqstp)
+		return nfs_ok;
+
+	xprt = rqstp->rq_xprt;
 
 	if (exp->ex_xprtsec_modes & NFSEXP_XPRTSEC_NONE) {
 		if (!test_bit(XPT_TLS_SESSION, &xprt->xpt_flags))
@@ -1098,17 +1117,17 @@ __be32 check_nfsd_access(struct svc_export *exp, struct svc_rqst *rqstp)
 ok:
 	/* legacy gss-only clients are always OK: */
 	if (exp->ex_client == rqstp->rq_gssclient)
-		return 0;
+		return nfs_ok;
 	/* ip-address based client; check sec= export option: */
 	for (f = exp->ex_flavors; f < end; f++) {
 		if (f->pseudoflavor == rqstp->rq_cred.cr_flavor)
-			return 0;
+			return nfs_ok;
 	}
 	/* defaults in absence of sec= options: */
 	if (exp->ex_nflavors == 0) {
 		if (rqstp->rq_cred.cr_flavor == RPC_AUTH_NULL ||
 		    rqstp->rq_cred.cr_flavor == RPC_AUTH_UNIX)
-			return 0;
+			return nfs_ok;
 	}
 
 	/* If the compound op contains a spo_must_allowed op,
@@ -1118,7 +1137,7 @@ __be32 check_nfsd_access(struct svc_export *exp, struct svc_rqst *rqstp)
 	 */
 
 	if (nfsd4_spo_must_allow(rqstp))
-		return 0;
+		return nfs_ok;
 
 denied:
 	return nfserr_wrongsec;
-- 
2.45.2