The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x e4f574ca9c6dfa66695bb054ff5df43ecea873ec # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2025101611-revisit-ranging-52d6@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From e4f574ca9c6dfa66695bb054ff5df43ecea873ec Mon Sep 17 00:00:00 2001 From: Scott Mayhew smayhew@redhat.com Date: Wed, 6 Aug 2025 15:15:43 -0400 Subject: [PATCH] nfsd: decouple the xprtsec policy check from check_nfsd_access()

A while back I had reported that an NFSv3 client could successfully mount using '-o xprtsec=none' an export that had been exported with 'xprtsec=tls:mtls'. By "successfully" I mean that the mount command would succeed and the mount would show up in /proc/mount. Attempting to do anything futher with the mount would be met with NFS3ERR_ACCES.

This was fixed (albeit accidentally) by commit bb4f07f2409c ("nfsd: Fix NFSD_MAY_BYPASS_GSS and NFSD_MAY_BYPASS_GSS_ON_ROOT") and was subsequently re-broken by commit 0813c5f01249 ("nfsd: fix access checking for NLM under XPRTSEC policies").

Transport Layer Security isn't an RPC security flavor or pseudo-flavor, so we shouldn't be conflating them when determining whether the access checks can be bypassed. Split check_nfsd_access() into two helpers, and have __fh_verify() call the helpers directly since __fh_verify() has logic that allows one or both of the checks to be skipped. All other sites will continue to call check_nfsd_access().

Link: https://lore.kernel.org/linux-nfs/ZjO3Qwf_G87yNXb2@aion/ Fixes: 9280c5774314 ("NFSD: Handle new xprtsec= export option") Cc: stable@vger.kernel.org Signed-off-by: Scott Mayhew smayhew@redhat.com Signed-off-by: Chuck Lever chuck.lever@oracle.com

diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c index cadfc2bae60e..95b5681152c4 100644 --- a/fs/nfsd/export.c +++ b/fs/nfsd/export.c @@ -1082,50 +1082,62 @@ static struct svc_export *exp_find(struct cache_detail *cd, }

/** - * check_nfsd_access - check if access to export is allowed. + * check_xprtsec_policy - check if access to export is allowed by the + * xprtsec policy * @exp: svc_export that is being accessed. - * @rqstp: svc_rqst attempting to access @exp (will be NULL for LOCALIO). - * @may_bypass_gss: reduce strictness of authorization check + * @rqstp: svc_rqst attempting to access @exp. + * + * Helper function for check_nfsd_access(). Note that callers should be + * using check_nfsd_access() instead of calling this function directly. The + * one exception is __fh_verify() since it has logic that may result in one + * or both of the helpers being skipped. * * 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, - bool may_bypass_gss) +__be32 check_xprtsec_policy(struct svc_export *exp, struct svc_rqst *rqstp) { - struct exp_flavor_info *f, *end = exp->ex_flavors + exp->ex_nflavors; - struct svc_xprt *xprt; - - /* - * If rqstp is NULL, this is a LOCALIO request which will only - * ever use a filehandle/credential pair for which access has - * been affirmed (by ACCESS or OPEN NFS requests) over the - * wire. So there is no need for further checks here. - */ - if (!rqstp) - return nfs_ok; - - xprt = rqstp->rq_xprt; + struct svc_xprt *xprt = rqstp->rq_xprt;

if (exp->ex_xprtsec_modes & NFSEXP_XPRTSEC_NONE) { if (!test_bit(XPT_TLS_SESSION, &xprt->xpt_flags)) - goto ok; + return nfs_ok; } if (exp->ex_xprtsec_modes & NFSEXP_XPRTSEC_TLS) { if (test_bit(XPT_TLS_SESSION, &xprt->xpt_flags) && !test_bit(XPT_PEER_AUTH, &xprt->xpt_flags)) - goto ok; + return nfs_ok; } if (exp->ex_xprtsec_modes & NFSEXP_XPRTSEC_MTLS) { if (test_bit(XPT_TLS_SESSION, &xprt->xpt_flags) && test_bit(XPT_PEER_AUTH, &xprt->xpt_flags)) - goto ok; + return nfs_ok; } - if (!may_bypass_gss) - goto denied; + return nfserr_wrongsec; +} + +/** + * check_security_flavor - check if access to export is allowed by the + * security flavor + * @exp: svc_export that is being accessed. + * @rqstp: svc_rqst attempting to access @exp. + * @may_bypass_gss: reduce strictness of authorization check + * + * Helper function for check_nfsd_access(). Note that callers should be + * using check_nfsd_access() instead of calling this function directly. The + * one exception is __fh_verify() since it has logic that may result in one + * or both of the helpers being skipped. + * + * Return values: + * %nfs_ok if access is granted, or + * %nfserr_wrongsec if access is denied + */ +__be32 check_security_flavor(struct svc_export *exp, struct svc_rqst *rqstp, + bool may_bypass_gss) +{ + struct exp_flavor_info *f, *end = exp->ex_flavors + exp->ex_nflavors;

-ok: /* legacy gss-only clients are always OK: */ if (exp->ex_client == rqstp->rq_gssclient) return nfs_ok; @@ -1167,10 +1179,30 @@ __be32 check_nfsd_access(struct svc_export *exp, struct svc_rqst *rqstp, } }

-denied: return nfserr_wrongsec; }

+/** + * check_nfsd_access - check if access to export is allowed. + * @exp: svc_export that is being accessed. + * @rqstp: svc_rqst attempting to access @exp. + * @may_bypass_gss: reduce strictness of authorization check + * + * 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, + bool may_bypass_gss) +{ + __be32 status; + + status = check_xprtsec_policy(exp, rqstp); + if (status != nfs_ok) + return status; + return check_security_flavor(exp, rqstp, may_bypass_gss); +} + /* * Uses rq_client and rq_gssclient to find an export; uses rq_client (an * auth_unix client) if it's available and has secinfo information; diff --git a/fs/nfsd/export.h b/fs/nfsd/export.h index b9c0adb3ce09..ef5581911d5b 100644 --- a/fs/nfsd/export.h +++ b/fs/nfsd/export.h @@ -101,6 +101,9 @@ struct svc_expkey {

struct svc_cred; int nfsexp_flags(struct svc_cred *cred, struct svc_export *exp); +__be32 check_xprtsec_policy(struct svc_export *exp, struct svc_rqst *rqstp); +__be32 check_security_flavor(struct svc_export *exp, struct svc_rqst *rqstp, + bool may_bypass_gss); __be32 check_nfsd_access(struct svc_export *exp, struct svc_rqst *rqstp, bool may_bypass_gss);

diff --git a/fs/nfsd/nfsfh.c b/fs/nfsd/nfsfh.c index f4c2fb3dd5d0..062cfc18d8c6 100644 --- a/fs/nfsd/nfsfh.c +++ b/fs/nfsd/nfsfh.c @@ -364,10 +364,30 @@ __fh_verify(struct svc_rqst *rqstp, if (error) goto out;

+ /* + * If rqstp is NULL, this is a LOCALIO request which will only + * ever use a filehandle/credential pair for which access has + * been affirmed (by ACCESS or OPEN NFS requests) over the + * wire. Skip both the xprtsec policy and the security flavor + * checks. + */ + if (!rqstp) + goto check_permissions; + if ((access & NFSD_MAY_NLM) && (exp->ex_flags & NFSEXP_NOAUTHNLM)) /* NLM is allowed to fully bypass authentication */ goto out;

+ /* + * NLM is allowed to bypass the xprtsec policy check because lockd + * doesn't support xprtsec. + */ + if (!(access & NFSD_MAY_NLM)) { + error = check_xprtsec_policy(exp, rqstp); + if (error) + goto out; + } + if (access & NFSD_MAY_BYPASS_GSS) may_bypass_gss = true; /* @@ -379,13 +399,15 @@ __fh_verify(struct svc_rqst *rqstp, && exp->ex_path.dentry == dentry) may_bypass_gss = true;

- error = check_nfsd_access(exp, rqstp, may_bypass_gss); + error = check_security_flavor(exp, rqstp, may_bypass_gss); if (error) goto out; + /* During LOCALIO call to fh_verify will be called with a NULL rqstp */ if (rqstp) svc_xprt_set_valid(rqstp->rq_xprt);

+check_permissions: /* Finally, check access permissions. */ error = nfsd_permission(cred, exp, dentry, access); out: