From patchwork Thu Sep 12 22:19:17 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Pali_Roh=C3=A1r?= X-Patchwork-Id: 13802739 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AE0DF18EFED; Thu, 12 Sep 2024 22:20:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726179620; cv=none; b=P4baKAOh2SbrOvrtVL4HyRyZ4I8EIREjhM0JY6e50xp15iaXutkW4v51BB5trUPVQw/RPSg9kYVsGHVYmTUQ0DIa4VSJiJ4r0YkeYrHDfLmEViDDQY3P/nwN15tciVifJjNXPa4u1Izt/VLlR7etoxinRSHhyj5/gk8PYDN/vpk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726179620; c=relaxed/simple; bh=nj9fV5kOVzpzl9DstAMQLd8D+jcdOATomopimDXm1ww=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version:Content-Type; b=Xtt3rPNJ1aWQzj5CyFV0VpuiYIjBfnantfhCkspjOv1lnaBLDrWpSojULkAQpLGbrn4hRUTqLjLRt62RhXitpNry9nugGAuVryARAvnIqmm+zMyjBFxcsj7NSLVrcTss47uWEE2IhiID9uhcRGiTKYdi2v5vCJy1Z9INCHWNifo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=kK/OzA+n; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="kK/OzA+n" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E3A76C4CEC3; Thu, 12 Sep 2024 22:20:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1726179620; bh=nj9fV5kOVzpzl9DstAMQLd8D+jcdOATomopimDXm1ww=; h=From:To:Cc:Subject:Date:From; b=kK/OzA+nauT1/FdtJCLjvkypJ6WJw0pRAmWoAoJc3H0kyOBUf2/Xrc0hmD5ET/Cgj 6lX/JNF92ihjRRKipMXlS5LLPWJmkUiQPuE94I7MHCeb1lh9Sxa7IjC7ZiUXwP/7AN rNu3lINp2wqy6EEuRT7EyuCiUmonnphYAsVgjODRANsHO5giVHRe3WXAhPodFdWmmE a7JF3AkQI+T1RgnUWSNDNBQT8mGiHQeNt7RsjI/eTkKx7Z1RLZsF4aAVP90RCWcAza TeIwNRJ3nRSHGwZFUqianhlOCDMVM6YxI9GPf8eFiMIEJG+vrSNRqFSS/qgcw51vvQ aCfUD3VcgzZTQ== Received: by pali.im (Postfix) id 43A0D5E9; Fri, 13 Sep 2024 00:20:15 +0200 (CEST) From: =?utf-8?q?Pali_Roh=C3=A1r?= To: Chuck Lever , Jeff Layton , Neil Brown , Olga Kornievskaia , Dai Ngo , Tom Talpey Cc: linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] nfsd: Fix NFSD_MAY_BYPASS_GSS and NFSD_MAY_BYPASS_GSS_ON_ROOT Date: Fri, 13 Sep 2024 00:19:17 +0200 Message-Id: <20240912221917.23802-1-pali@kernel.org> X-Mailer: git-send-email 2.39.2 Precedence: bulk X-Mailing-List: linux-nfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Currently NFSD_MAY_BYPASS_GSS and NFSD_MAY_BYPASS_GSS_ON_ROOT do not bypass only GSS, but bypass any authentication method. This is problem specially for NFS3 AUTH_NULL-only exports. The purpose of NFSD_MAY_BYPASS_GSS_ON_ROOT is described in RFC 2623, section 2.3.2, to allow mounting NFS2/3 GSS-only export without authentication. So few procedures which do not expose security risk used during mount time can be called also with AUTH_NONE or AUTH_SYS, to allow client mount operation to finish successfully. The problem with current implementation is that for AUTH_NULL-only exports, the NFSD_MAY_BYPASS_GSS_ON_ROOT is active also for NFS3 AUTH_UNIX mount attempts which confuse NFS3 clients, and make them think that AUTH_UNIX is enabled and is working. Linux NFS3 client never switches from AUTH_UNIX to AUTH_NONE on active mount, which makes the mount inaccessible. Fix the NFSD_MAY_BYPASS_GSS and NFSD_MAY_BYPASS_GSS_ON_ROOT implementation and really allow to bypass only exports which have some GSS auth flavor enabled. The result would be: For AUTH_NULL-only export if client attempts to do mount with AUTH_UNIX flavor then it will receive access errors, which instruct client that AUTH_UNIX flavor is not usable and will either try other auth flavor (AUTH_NULL if enabled) or fails mount procedure. This should fix problems with AUTH_NULL-only or AUTH_UNIX-only exports if client attempts to mount it with other auth flavor (e.g. with AUTH_NULL for AUTH_UNIX-only export, or with AUTH_UNIX for AUTH_NULL-only export). Signed-off-by: Pali Rohár --- fs/nfsd/export.c | 19 ++++++++++++++++++- fs/nfsd/export.h | 2 +- fs/nfsd/nfs4proc.c | 2 +- fs/nfsd/nfs4xdr.c | 2 +- fs/nfsd/nfsfh.c | 12 +++++++++--- fs/nfsd/vfs.c | 2 +- 6 files changed, 31 insertions(+), 8 deletions(-) diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c index 50b3135d07ac..eb11d3fdffe1 100644 --- a/fs/nfsd/export.c +++ b/fs/nfsd/export.c @@ -1074,7 +1074,7 @@ static struct svc_export *exp_find(struct cache_detail *cd, return exp; } -__be32 check_nfsd_access(struct svc_export *exp, struct svc_rqst *rqstp) +__be32 check_nfsd_access(struct svc_export *exp, struct svc_rqst *rqstp, bool may_bypass_gss) { struct exp_flavor_info *f, *end = exp->ex_flavors + exp->ex_nflavors; struct svc_xprt *xprt = rqstp->rq_xprt; @@ -1120,6 +1120,23 @@ __be32 check_nfsd_access(struct svc_export *exp, struct svc_rqst *rqstp) if (nfsd4_spo_must_allow(rqstp)) return 0; + /* Some calls may be processed without authentication + * on GSS exports. For example NFS2/3 calls on root + * directory, see section 2.3.2 of rfc 2623. + * For "may_bypass_gss" check that export has really + * enabled some GSS flavor and also check that the + * used auth flavor is without auth (none or sys). + */ + 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_GSS || + f->pseudoflavor >= RPC_AUTH_GSS_KRB5) + return 0; + } + } + denied: return rqstp->rq_vers < 4 ? nfserr_acces : nfserr_wrongsec; } diff --git a/fs/nfsd/export.h b/fs/nfsd/export.h index ca9dc230ae3d..dc7cf4f6ac53 100644 --- a/fs/nfsd/export.h +++ b/fs/nfsd/export.h @@ -100,7 +100,7 @@ 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_nfsd_access(struct svc_export *exp, struct svc_rqst *rqstp); +__be32 check_nfsd_access(struct svc_export *exp, struct svc_rqst *rqstp, bool may_bypass_gss); /* * Function declarations diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c index 2e39cf2e502a..0f67f4a7b8b2 100644 --- a/fs/nfsd/nfs4proc.c +++ b/fs/nfsd/nfs4proc.c @@ -2791,7 +2791,7 @@ nfsd4_proc_compound(struct svc_rqst *rqstp) if (current_fh->fh_export && need_wrongsec_check(rqstp)) - op->status = check_nfsd_access(current_fh->fh_export, rqstp); + op->status = check_nfsd_access(current_fh->fh_export, rqstp, false); } encode_op: if (op->status == nfserr_replay_me) { diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c index 97f583777972..b45ea5757652 100644 --- a/fs/nfsd/nfs4xdr.c +++ b/fs/nfsd/nfs4xdr.c @@ -3775,7 +3775,7 @@ nfsd4_encode_entry4_fattr(struct nfsd4_readdir *cd, const char *name, nfserr = nfserrno(err); goto out_put; } - nfserr = check_nfsd_access(exp, cd->rd_rqstp); + nfserr = check_nfsd_access(exp, cd->rd_rqstp, false); if (nfserr) goto out_put; diff --git a/fs/nfsd/nfsfh.c b/fs/nfsd/nfsfh.c index dd4e11a703aa..ed0eabfa3cb0 100644 --- a/fs/nfsd/nfsfh.c +++ b/fs/nfsd/nfsfh.c @@ -329,6 +329,7 @@ fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type, int access) { struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id); struct svc_export *exp = NULL; + bool may_bypass_gss = false; struct dentry *dentry; __be32 error; @@ -375,8 +376,13 @@ fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type, int access) * which clients virtually always use auth_sys for, * even while using RPCSEC_GSS for NFS. */ - if (access & NFSD_MAY_LOCK || access & NFSD_MAY_BYPASS_GSS) + if (access & NFSD_MAY_LOCK) goto skip_pseudoflavor_check; + /* + * NFS4 PUTFH may bypass GSS (see nfsd4_putfh() in nfs4proc.c). + */ + if (access & NFSD_MAY_BYPASS_GSS) + may_bypass_gss = true; /* * Clients may expect to be able to use auth_sys during mount, * even if they use gss for everything else; see section 2.3.2 @@ -384,9 +390,9 @@ fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type, int access) */ if (access & NFSD_MAY_BYPASS_GSS_ON_ROOT && exp->ex_path.dentry == dentry) - goto skip_pseudoflavor_check; + may_bypass_gss = true; - error = check_nfsd_access(exp, rqstp); + error = check_nfsd_access(exp, rqstp, may_bypass_gss); if (error) goto out; diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c index 29b1f3613800..b2f5ea7c2187 100644 --- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -320,7 +320,7 @@ nfsd_lookup(struct svc_rqst *rqstp, struct svc_fh *fhp, const char *name, err = nfsd_lookup_dentry(rqstp, fhp, name, len, &exp, &dentry); if (err) return err; - err = check_nfsd_access(exp, rqstp); + err = check_nfsd_access(exp, rqstp, false); if (err) goto out; /*