On Wed, 12 Mar 2025, Olga Kornievskaia wrote:
> On Tue, Mar 11, 2025 at 11:28 AM Olga Kornievskaia <aglo@xxxxxxxxx> wrote:
> >
> > On Thu, Oct 17, 2024 at 5:42 PM NeilBrown <neilb@xxxxxxx> wrote:
> > >
> > >
> > > NFSD_MAY_LOCK means a few different things.
> > > - it means that GSS is not required.
> > > - it means that with NFSEXP_NOAUTHNLM, authentication is not required
> > > - it means that OWNER_OVERRIDE is allowed.
> > >
> > > None of these are specific to locking, they are specific to the NLM
> > > protocol.
> > > So:
> > > - rename to NFSD_MAY_NLM
> > > - set NFSD_MAY_OWNER_OVERRIDE and NFSD_MAY_BYPASS_GSS in nlm_fopen()
> > > so that NFSD_MAY_NLM doesn't need to imply these.
> > > - move the test on NFSEXP_NOAUTHNLM out of nfsd_permission() and
> > > into fh_verify where other special-case tests on the MAY flags
> > > happen. nfsd_permission() can be called from other places than
> > > fh_verify(), but none of these will have NFSD_MAY_NLM.
> >
> > This patch breaks NLM when used in combination with TLS.
>
> I was too quick to link this to TLS. It's presence of security policy
> so sec=krb* causes the same problems.
>
> > If exports
> > have xprtsec=tls:mtls and mount is done with tls/mtls, the server
> > won't give any locks and client will get "no locks available" error.
> >
> > >
> > > Signed-off-by: NeilBrown <neilb@xxxxxxx>
> > > ---
> > >
> > > No change from previous patch - the corruption in the email has been
> > > avoided (I hope).
> > >
> > >
> > > fs/nfsd/lockd.c | 13 +++++++++++--
> > > fs/nfsd/nfsfh.c | 12 ++++--------
> > > fs/nfsd/trace.h | 2 +-
> > > fs/nfsd/vfs.c | 12 +-----------
> > > fs/nfsd/vfs.h | 2 +-
> > > 5 files changed, 18 insertions(+), 23 deletions(-)
> > >
> > > diff --git a/fs/nfsd/lockd.c b/fs/nfsd/lockd.c
> > > index 46a7f9b813e5..edc9f75dc75c 100644
> > > --- a/fs/nfsd/lockd.c
> > > +++ b/fs/nfsd/lockd.c
> > > @@ -38,11 +38,20 @@ nlm_fopen(struct svc_rqst *rqstp, struct nfs_fh *f, struct file **filp,
> > > memcpy(&fh.fh_handle.fh_raw, f->data, f->size);
> > > fh.fh_export = NULL;
> > >
> > > + /*
> > > + * Allow BYPASS_GSS as some client implementations use AUTH_SYS
> > > + * for NLM even when GSS is used for NFS.
> > > + * Allow OWNER_OVERRIDE as permission might have been changed
> > > + * after the file was opened.
> > > + * Pass MAY_NLM so that authentication can be completely bypassed
> > > + * if NFSEXP_NOAUTHNLM is set. Some older clients use AUTH_NULL
> > > + * for NLM requests.
> > > + */
> > > access = (mode == O_WRONLY) ? NFSD_MAY_WRITE : NFSD_MAY_READ;
> > > - access |= NFSD_MAY_LOCK;
> > > + access |= NFSD_MAY_NLM | NFSD_MAY_OWNER_OVERRIDE | NFSD_MAY_BYPASS_GSS;
> > > nfserr = nfsd_open(rqstp, &fh, S_IFREG, access, filp);
> > > fh_put(&fh);
> > > - /* We return nlm error codes as nlm doesn't know
> > > + /* We return nlm error codes as nlm doesn't know
> > > * about nfsd, but nfsd does know about nlm..
> > > */
> > > switch (nfserr) {
> > > diff --git a/fs/nfsd/nfsfh.c b/fs/nfsd/nfsfh.c
> > > index 40533f7c7297..6a831cb242df 100644
> > > --- a/fs/nfsd/nfsfh.c
> > > +++ b/fs/nfsd/nfsfh.c
> > > @@ -363,13 +363,10 @@ __fh_verify(struct svc_rqst *rqstp,
> > > if (error)
> > > goto out;
> > >
> > > - /*
> > > - * pseudoflavor restrictions are not enforced on NLM,
> > > - * which clients virtually always use auth_sys for,
> > > - * even while using RPCSEC_GSS for NFS.
> > > - */
> > > - if (access & NFSD_MAY_LOCK)
> > > - goto skip_pseudoflavor_check;
> > > + if ((access & NFSD_MAY_NLM) && (exp->ex_flags & NFSEXP_NOAUTHNLM))
>
> I think this should either be an OR or the fact that "nlm but only
> with insecurelock export option and not other" is the only way to
> bypass checking is wrong. I think it's just a check for NLM that
> stays.
I don't think that NLM gets a complete bypass unless no_auth_nlm is set.
For the case you are describing, I think NFSD_MAY_BYPASS_GSS is supposed
to make it work.
I assume the NLM request is arriving with AUTH_SYS authentication?
So check_nfsd_access() is being called with may_bypass_gss and this:
if (may_bypass_gss && (
rqstp->rq_cred.cr_flavor == RPC_AUTH_NULL ||
rqstp->rq_cred.cr_flavor == RPC_AUTH_UNIX)) {
for (f = exp->ex_flavors; f < end; f++) {
if (f->pseudoflavor >= RPC_AUTH_DES)
return 0;
}
}
in check_nfsd_access() should succeed.
Can you add some tracing and see what is happening in here?
Maybe the "goto denied" earlier in the function is being reached. I
don't fully understand the TLS code yet - maybe it needs some test on
may_bypass_gss.
Thanks,
NeilBrown
>
> > > + /* NLM is allowed to fully bypass authentication */
> > > + goto out;
> > > +
> > > if (access & NFSD_MAY_BYPASS_GSS)
> > > may_bypass_gss = true;
> > > /*
> > > @@ -385,7 +382,6 @@ __fh_verify(struct svc_rqst *rqstp,
> > > if (error)
> > > goto out;
> > >
> > > -skip_pseudoflavor_check:
> > > /* Finally, check access permissions. */
> > > error = nfsd_permission(cred, exp, dentry, access);
> > > out:
> > > diff --git a/fs/nfsd/trace.h b/fs/nfsd/trace.h
> > > index b8470d4cbe99..3448e444d410 100644
> > > --- a/fs/nfsd/trace.h
> > > +++ b/fs/nfsd/trace.h
> > > @@ -79,7 +79,7 @@ DEFINE_NFSD_XDR_ERR_EVENT(cant_encode);
> > > { NFSD_MAY_READ, "READ" }, \
> > > { NFSD_MAY_SATTR, "SATTR" }, \
> > > { NFSD_MAY_TRUNC, "TRUNC" }, \
> > > - { NFSD_MAY_LOCK, "LOCK" }, \
> > > + { NFSD_MAY_NLM, "NLM" }, \
> > > { NFSD_MAY_OWNER_OVERRIDE, "OWNER_OVERRIDE" }, \
> > > { NFSD_MAY_LOCAL_ACCESS, "LOCAL_ACCESS" }, \
> > > { NFSD_MAY_BYPASS_GSS_ON_ROOT, "BYPASS_GSS_ON_ROOT" }, \
> > > diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
> > > index 51f5a0b181f9..2610638f4301 100644
> > > --- a/fs/nfsd/vfs.c
> > > +++ b/fs/nfsd/vfs.c
> > > @@ -2509,7 +2509,7 @@ nfsd_permission(struct svc_cred *cred, struct svc_export *exp,
> > > (acc & NFSD_MAY_EXEC)? " exec" : "",
> > > (acc & NFSD_MAY_SATTR)? " sattr" : "",
> > > (acc & NFSD_MAY_TRUNC)? " trunc" : "",
> > > - (acc & NFSD_MAY_LOCK)? " lock" : "",
> > > + (acc & NFSD_MAY_NLM)? " nlm" : "",
> > > (acc & NFSD_MAY_OWNER_OVERRIDE)? " owneroverride" : "",
> > > inode->i_mode,
> > > IS_IMMUTABLE(inode)? " immut" : "",
> > > @@ -2534,16 +2534,6 @@ nfsd_permission(struct svc_cred *cred, struct svc_export *exp,
> > > if ((acc & NFSD_MAY_TRUNC) && IS_APPEND(inode))
> > > return nfserr_perm;
> > >
> > > - if (acc & NFSD_MAY_LOCK) {
> > > - /* If we cannot rely on authentication in NLM requests,
> > > - * just allow locks, otherwise require read permission, or
> > > - * ownership
> > > - */
> > > - if (exp->ex_flags & NFSEXP_NOAUTHNLM)
> > > - return 0;
> > > - else
> > > - acc = NFSD_MAY_READ | NFSD_MAY_OWNER_OVERRIDE;
> > > - }
> > > /*
> > > * The file owner always gets access permission for accesses that
> > > * would normally be checked at open time. This is to make
> > > diff --git a/fs/nfsd/vfs.h b/fs/nfsd/vfs.h
> > > index 854fb95dfdca..f9b09b842856 100644
> > > --- a/fs/nfsd/vfs.h
> > > +++ b/fs/nfsd/vfs.h
> > > @@ -20,7 +20,7 @@
> > > #define NFSD_MAY_READ 0x004 /* == MAY_READ */
> > > #define NFSD_MAY_SATTR 0x008
> > > #define NFSD_MAY_TRUNC 0x010
> > > -#define NFSD_MAY_LOCK 0x020
> > > +#define NFSD_MAY_NLM 0x020 /* request is from lockd */
> > > #define NFSD_MAY_MASK 0x03f
> > >
> > > /* extra hints to permission and open routines: */
> > >
> > > base-commit: c4e418a53fe30d8e1da68f5aabca352b682fd331
> > > --
> > > 2.46.0
> > >
> > >
>
