nfsd: allow secinfo to bypass gss checks
Subsystems (2)
PATCH 1/1 nfsd: allow secinfo to bypass gss checks
Also planning to queue this up for 3.1.... Objections?
commit ea53eb9a87848610f1a2465881d8ef6ab6c62c59
Author: J. Bruce Fields <[email protected]> Date: Wed Jun 29 18:33:11 2011 -0400
nfsd: allow secinfo to bypass gss checks
PUTFH+SECINFO should succeed and return a security list even when using an authentication flavor not permitted on the given filehandle.
There's the risk of a small information leak here: as part of the SECINFO, we have to do a lookup. If that lookup fails, we return the error from that lookup instead of a secinfo list. That allows an unprivileged user to answer the question "does a file named $x exist in directory $d" by guessing a filehandle for $d and then sending a secinfo request for $x and seeing whether or not they get NFS4ERR_NOENT.
To avoid that, we return secinfo for the parent in the NOENT case.
fs/nfsd/nfs4proc.c +19 -4
@@ -762,19 +762,34 @@ nfsd4_secinfo(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,__be32 err;fh_init (&resfh,NFS4_FHSIZE ); - err =fh_verify (rqstp, &cstate->current_fh,S_IFDIR ,NFSD_MAY_EXEC ); + err =fh_verify (rqstp, &cstate->current_fh,S_IFDIR , +NFSD_MAY_EXEC |NFSD_MAY_BYPASS_GSS );if (err)return err; +/* +* XXX: arguably we should do this with elevated privileges, to +* ensure consistent results regardless of the cred used by the +* client: +*/ err =nfsd_lookup_dentry (rqstp, &cstate->current_fh, secinfo->si_name, secinfo->si_namelen, &exp, &dentry);if (err)return err;if (dentry->d_inode ==NULL ) { +/* +* An nfserr_noent return would tell the rpc caller +* (who may be unprivileged) that a file by that name +* does not exist in this directory. That may be +* information we don't want to give out. So return +* secinfo list for the parent in that case instead of +* failing here. +*/ exp_put (exp); - err = nfserr_noent; - }else - secinfo->si_exp = exp; + exp = cstate->current_fh.fh_export; +exp_get (exp); + } + secinfo->si_exp = exp;dput (dentry);if (cstate->minorversion)/* See rfc 5661 section 2.6.3.1.1.8 */