[ Upstream commit e4f574ca9c6dfa66695bb054ff5df43ecea873ec ]
This is a backport of e4f574ca9c6d specifically for the 6.6-stable kernel. It differs from the upstream version mainly in that it's working around the absence of some 6.12-era commits: - 1459ad57673b nfsd: Move error code mapping to per-version proc code. - 0a183f24a7ae NFSD: Handle @rqstp == NULL in check_nfsd_access() - 5e66d2d92a1c nfsd: factor out __fh_verify to allow NULL rqstp to be passed
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.
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") Signed-off-by: Scott Mayhew smayhew@redhat.com --- fs/nfsd/export.c | 60 +++++++++++++++++++++++++++++++++++++++++------- fs/nfsd/export.h | 2 ++ fs/nfsd/nfsfh.c | 12 +++++++++- 3 files changed, 65 insertions(+), 9 deletions(-)
diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c index 4b5d998cbc2f..f4e77859aa85 100644 --- a/fs/nfsd/export.c +++ b/fs/nfsd/export.c @@ -1071,28 +1071,62 @@ static struct svc_export *exp_find(struct cache_detail *cd, return exp; }
-__be32 check_nfsd_access(struct svc_export *exp, struct svc_rqst *rqstp) +/** + * 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. + * + * 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_acces or %nfserr_wrongsec if access is denied + */ +__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 = 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; } - goto denied;
-ok: + return rqstp->rq_vers < 4 ? nfserr_acces : nfserr_wrongsec; +} + +/** + * check_security_flavor - 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. + * + * 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_acces or %nfserr_wrongsec if access is denied + */ +__be32 check_security_flavor(struct svc_export *exp, struct svc_rqst *rqstp) +{ + struct exp_flavor_info *f, *end = exp->ex_flavors + exp->ex_nflavors; + /* legacy gss-only clients are always OK: */ if (exp->ex_client == rqstp->rq_gssclient) return 0; @@ -1117,10 +1151,20 @@ __be32 check_nfsd_access(struct svc_export *exp, struct svc_rqst *rqstp) if (nfsd4_spo_must_allow(rqstp)) return 0;
-denied: return rqstp->rq_vers < 4 ? nfserr_acces : nfserr_wrongsec; }
+__be32 check_nfsd_access(struct svc_export *exp, struct svc_rqst *rqstp) +{ + __be32 status; + + status = check_xprtsec_policy(exp, rqstp); + if (status != nfs_ok) + return status; + + return check_security_flavor(exp, rqstp); +} + /* * 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 ca9dc230ae3d..4a48b2ad5606 100644 --- a/fs/nfsd/export.h +++ b/fs/nfsd/export.h @@ -100,6 +100,8 @@ struct svc_expkey { #define EX_WGATHER(exp) ((exp)->ex_flags & NFSEXP_GATHERED_WRITES)
int nfsexp_flags(struct svc_rqst *rqstp, 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); __be32 check_nfsd_access(struct svc_export *exp, struct svc_rqst *rqstp);
/* diff --git a/fs/nfsd/nfsfh.c b/fs/nfsd/nfsfh.c index c2495d98c189..283c1a60c846 100644 --- a/fs/nfsd/nfsfh.c +++ b/fs/nfsd/nfsfh.c @@ -370,6 +370,16 @@ fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type, int access) if (error) goto out;
+ /* + * NLM is allowed to bypass the xprtsec policy check because lockd + * doesn't support xprtsec. + */ + if (!(access & NFSD_MAY_LOCK)) { + error = check_xprtsec_policy(exp, rqstp); + if (error) + goto out; + } + /* * pseudoflavor restrictions are not enforced on NLM, * which clients virtually always use auth_sys for, @@ -386,7 +396,7 @@ fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type, int access) && exp->ex_path.dentry == dentry) goto skip_pseudoflavor_check;
- error = check_nfsd_access(exp, rqstp); + error = check_security_flavor(exp, rqstp); if (error) goto out;