Return-Path: linux-nfs-owner@vger.kernel.org Received: from aserp1040.oracle.com ([141.146.126.69]:36946 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758674Ab3BGP6g convert rfc822-to-8bit (ORCPT ); Thu, 7 Feb 2013 10:58:36 -0500 Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 6.2 \(1499\)) Subject: Re: [PATCH] SUNRPC: Refactor nfsd4_do_encode_secinfo() From: Chuck Lever In-Reply-To: <20130207150213.GC3222@fieldses.org> Date: Thu, 7 Feb 2013 10:58:25 -0500 Cc: Linux NFS Mailing List Message-Id: <87316F41-4E5E-473C-A372-0AFC6721A355@oracle.com> References: <20130201220308.13518.82164.stgit@seurat.1015granger.net> <20130207150213.GC3222@fieldses.org> To: "J. Bruce Fields" Sender: linux-nfs-owner@vger.kernel.org List-ID: On Feb 7, 2013, at 10:02 AM, J. Bruce Fields wrote: > On Fri, Feb 01, 2013 at 05:43:44PM -0500, Chuck Lever wrote: >> Clean up. This matches a similar API for the client side, and >> keeps ULP fingers out the of the GSS mech switch. >> >> Signed-off-by: Chuck Lever >> Acked-by: J. Bruce Fields >> --- >> >> Bruce- >> >> This version of the patch follows the existing logic in >> nfsd4_do_encode_secinfo(): If the RPC layer can't find GSS info >> that matches an export security flavor, it assumes the flavor is >> not a GSS pseudoflavor, and simply puts it on the wire. >> >> However, if the below XDR encoding logic is given a legitimate GSS >> pseudoflavor but the RPC layer says it does not support that >> pseudoflavor for some reason, then we leak GSS pseudoflavor numbers >> onto the wire. >> >> I confirmed this happens by blacklisting rpcsec_gss_krb5, then >> attempted a client transition from the pseudo-fs to a Kerberos-only >> share. The client received a flavor list containing the Kerberos >> pseudoflavor numbers, rather than GSS tuples. >> >> The encoder logic can check that each pseudoflavor is less than >> MAXFLAVOR before writing it into the buffer, to prevent this. But >> after "nflavs" is written into the XDR buffer, the encoder can't >> skip writing flavor information into the buffer when it discovers >> the RPC layer doesn't support that flavor. >> >> Is there some way of writing "nflavs" into the XDR buffer after >> the loop that writes the flavor information is complete? > > Yes, you can save a pointer and then go back and fill that in--see > encode_fattr for an example. Thanks, I will submit an additional patch that describes this issue and fixes it. I asked David Noveck, as one of the authors of RFC 3530, whether an NFS server should return a zero-length flavor list or an error if SECINFO can't find any flavors a client is allowed to use. His opinion was to return NFS4_OK and a zero-length flavor list. > > --b. > >> >> What if "nflavs" turns out to be zero? RFC 3530bis, 15.33.4 does >> not explicitly say what should be done if the array of security >> mechanisms for that client and file handle contains zero items. >> >> Or is there a better way to handle this situation? Also, should we >> care about this scenario? >> >> >> fs/nfsd/nfs4xdr.c | 24 +++++++++++------------ >> include/linux/sunrpc/auth.h | 2 ++ >> include/linux/sunrpc/gss_api.h | 3 +++ >> net/sunrpc/auth.c | 34 +++++++++++++++++++++++++++++++++ >> net/sunrpc/auth_gss/auth_gss.c | 1 + >> net/sunrpc/auth_gss/gss_mech_switch.c | 34 +++++++++++++++++++++++++++++++-- >> 6 files changed, 83 insertions(+), 15 deletions(-) >> >> diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c >> index 0dc1158..424f5a2 100644 >> --- a/fs/nfsd/nfs4xdr.c >> +++ b/fs/nfsd/nfs4xdr.c >> @@ -3127,10 +3127,9 @@ nfsd4_encode_rename(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd4_ >> >> static __be32 >> nfsd4_do_encode_secinfo(struct nfsd4_compoundres *resp, >> - __be32 nfserr,struct svc_export *exp) >> + __be32 nfserr, struct svc_export *exp) >> { >> - int i = 0; >> - u32 nflavs; >> + u32 i, nflavs; >> struct exp_flavor_info *flavs; >> struct exp_flavor_info def_flavs[2]; >> __be32 *p; >> @@ -3161,30 +3160,29 @@ nfsd4_do_encode_secinfo(struct nfsd4_compoundres *resp, >> WRITE32(nflavs); >> ADJUST_ARGS(); >> for (i = 0; i < nflavs; i++) { >> - u32 flav = flavs[i].pseudoflavor; >> - struct gss_api_mech *gm = gss_mech_get_by_pseudoflavor(flav); >> + struct rpcsec_gss_info info; >> >> - if (gm) { >> + if (rpcauth_get_gssinfo(flavs[i].pseudoflavor, &info) == 0) { >> RESERVE_SPACE(4); >> WRITE32(RPC_AUTH_GSS); >> ADJUST_ARGS(); >> - RESERVE_SPACE(4 + gm->gm_oid.len); >> - WRITE32(gm->gm_oid.len); >> - WRITEMEM(gm->gm_oid.data, gm->gm_oid.len); >> + RESERVE_SPACE(4 + info.oid.len); >> + WRITE32(info.oid.len); >> + WRITEMEM(info.oid.data, info.oid.len); >> ADJUST_ARGS(); >> RESERVE_SPACE(4); >> - WRITE32(0); /* qop */ >> + WRITE32(info.qop); >> ADJUST_ARGS(); >> RESERVE_SPACE(4); >> - WRITE32(gss_pseudoflavor_to_service(gm, flav)); >> + WRITE32(info.service); >> ADJUST_ARGS(); >> - gss_mech_put(gm); >> } else { >> RESERVE_SPACE(4); >> - WRITE32(flav); >> + WRITE32(flavs[i].pseudoflavor); >> ADJUST_ARGS(); >> } >> } >> + >> out: >> if (exp) >> exp_put(exp); >> diff --git a/include/linux/sunrpc/auth.h b/include/linux/sunrpc/auth.h >> index 476e97c..c34ac17 100644 >> --- a/include/linux/sunrpc/auth.h >> +++ b/include/linux/sunrpc/auth.h >> @@ -105,6 +105,7 @@ struct rpc_authops { >> void (*pipes_destroy)(struct rpc_auth *); >> int (*list_pseudoflavors)(rpc_authflavor_t *, int); >> rpc_authflavor_t (*info2flavor)(struct rpcsec_gss_info *); >> + int (*flavor2info)(rpc_authflavor_t, struct rpcsec_gss_info *); >> }; >> >> struct rpc_credops { >> @@ -140,6 +141,7 @@ int rpcauth_unregister(const struct rpc_authops *); >> struct rpc_auth * rpcauth_create(rpc_authflavor_t, struct rpc_clnt *); >> void rpcauth_release(struct rpc_auth *); >> rpc_authflavor_t rpcauth_get_pseudoflavor(rpc_authflavor_t, struct rpcsec_gss_info *); >> +int rpcauth_get_gssinfo(rpc_authflavor_t, struct rpcsec_gss_info *); >> int rpcauth_list_flavors(rpc_authflavor_t *, int); >> struct rpc_cred * rpcauth_lookup_credcache(struct rpc_auth *, struct auth_cred *, int); >> void rpcauth_init_cred(struct rpc_cred *, const struct auth_cred *, struct rpc_auth *, const struct rpc_credops *); >> diff --git a/include/linux/sunrpc/gss_api.h b/include/linux/sunrpc/gss_api.h >> index e8299b2..dc1e51b 100644 >> --- a/include/linux/sunrpc/gss_api.h >> +++ b/include/linux/sunrpc/gss_api.h >> @@ -132,6 +132,9 @@ void gss_mech_unregister(struct gss_api_mech *); >> /* Given a GSS security tuple, look up a pseudoflavor */ >> rpc_authflavor_t gss_mech_info2flavor(struct rpcsec_gss_info *); >> >> +/* Given a pseudoflavor, look up a GSS security tuple */ >> +int gss_mech_flavor2info(rpc_authflavor_t, struct rpcsec_gss_info *); >> + >> /* Returns a reference to a mechanism, given a name like "krb5" etc. */ >> struct gss_api_mech *gss_mech_get_by_name(const char *); >> >> diff --git a/net/sunrpc/auth.c b/net/sunrpc/auth.c >> index ec18827..4c551f9 100644 >> --- a/net/sunrpc/auth.c >> +++ b/net/sunrpc/auth.c >> @@ -158,6 +158,40 @@ rpcauth_get_pseudoflavor(rpc_authflavor_t flavor, struct rpcsec_gss_info *info) >> EXPORT_SYMBOL_GPL(rpcauth_get_pseudoflavor); >> >> /** >> + * rpcauth_get_gssinfo - find GSS tuple matching a GSS pseudoflavor >> + * @pseudoflavor: GSS pseudoflavor to match >> + * @info: rpcsec_gss_info structure to fill in >> + * >> + * Returns zero and fills in "info" if pseudoflavor matches a >> + * supported mechanism. >> + */ >> +int >> +rpcauth_get_gssinfo(rpc_authflavor_t pseudoflavor, struct rpcsec_gss_info *info) >> +{ >> + rpc_authflavor_t flavor = pseudoflavor_to_flavor(pseudoflavor); >> + const struct rpc_authops *ops; >> + int result; >> + >> + if ((ops = auth_flavors[flavor]) == NULL) >> + request_module("rpc-auth-%u", flavor); >> + spin_lock(&rpc_authflavor_lock); >> + ops = auth_flavors[flavor]; >> + if (ops == NULL || !try_module_get(ops->owner)) { >> + spin_unlock(&rpc_authflavor_lock); >> + return -ENOENT; >> + } >> + spin_unlock(&rpc_authflavor_lock); >> + >> + result = -ENOENT; >> + if (ops->flavor2info != NULL) >> + result = ops->flavor2info(pseudoflavor, info); >> + >> + module_put(ops->owner); >> + return result; >> +} >> +EXPORT_SYMBOL_GPL(rpcauth_get_gssinfo); >> + >> +/** >> * rpcauth_list_flavors - discover registered flavors and pseudoflavors >> * @array: array to fill in >> * @size: size of "array" >> diff --git a/net/sunrpc/auth_gss/auth_gss.c b/net/sunrpc/auth_gss/auth_gss.c >> index 4522297..ade24b2 100644 >> --- a/net/sunrpc/auth_gss/auth_gss.c >> +++ b/net/sunrpc/auth_gss/auth_gss.c >> @@ -1630,6 +1630,7 @@ static const struct rpc_authops authgss_ops = { >> .pipes_destroy = gss_pipes_dentries_destroy, >> .list_pseudoflavors = gss_mech_list_pseudoflavors, >> .info2flavor = gss_mech_info2flavor, >> + .flavor2info = gss_mech_flavor2info, >> }; >> >> static const struct rpc_credops gss_credops = { >> diff --git a/net/sunrpc/auth_gss/gss_mech_switch.c b/net/sunrpc/auth_gss/gss_mech_switch.c >> index c8da89e..a8d6ee5 100644 >> --- a/net/sunrpc/auth_gss/gss_mech_switch.c >> +++ b/net/sunrpc/auth_gss/gss_mech_switch.c >> @@ -240,8 +240,6 @@ gss_mech_get_by_pseudoflavor(u32 pseudoflavor) >> return gm; >> } >> >> -EXPORT_SYMBOL_GPL(gss_mech_get_by_pseudoflavor); >> - >> /** >> * gss_mech_list_pseudoflavors - Discover registered GSS pseudoflavors >> * @array: array to fill in >> @@ -314,6 +312,38 @@ rpc_authflavor_t gss_mech_info2flavor(struct rpcsec_gss_info *info) >> return pseudoflavor; >> } >> >> +/** >> + * gss_mech_flavor2info - look up a GSS tuple for a given pseudoflavor >> + * @pseudoflavor: GSS pseudoflavor to match >> + * @info: rpcsec_gss_info structure to fill in >> + * >> + * Returns zero and fills in "info" if pseudoflavor matches a >> + * supported mechanism. Otherwise a negative errno is returned. >> + */ >> +int gss_mech_flavor2info(rpc_authflavor_t pseudoflavor, struct rpcsec_gss_info *info) >> +{ >> + struct gss_api_mech *gm; >> + int i; >> + >> + gm = gss_mech_get_by_pseudoflavor(pseudoflavor); >> + if (gm == NULL) >> + return -ENOENT; >> + >> + for (i = 0; i < gm->gm_pf_num; i++) { >> + if (gm->gm_pfs[i].pseudoflavor == pseudoflavor) { >> + memcpy(info->oid.data, gm->gm_oid.data, gm->gm_oid.len); >> + info->oid.len = gm->gm_oid.len; >> + info->qop = gm->gm_pfs[i].qop; >> + info->service = gm->gm_pfs[i].service; >> + gss_mech_put(gm); >> + return 0; >> + } >> + } >> + >> + gss_mech_put(gm); >> + return -ENOENT; >> +} >> + >> u32 >> gss_pseudoflavor_to_service(struct gss_api_mech *gm, u32 pseudoflavor) >> { >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html > -- > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Chuck Lever chuck[dot]lever[at]oracle[dot]com