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authorJ. Bruce Fields <bfields@citi.umich.edu>2008-08-07 21:00:20 +0400
committerJ. Bruce Fields <bfields@citi.umich.edu>2008-09-30 01:56:56 +0400
commit04716e6621ff4abb422d64ba7b48718f52716a3e (patch)
tree742e2e7b6d4c7cf3a39f504000a49e57fe0b538b /fs/nfsd/nfsfh.c
parent5dd248f6f1ffe1f691fd66749e2a3dc8f8eb7b5e (diff)
downloadlinux-04716e6621ff4abb422d64ba7b48718f52716a3e.tar.xz
nfsd: permit unauthenticated stat of export root
RFC 2623 section 2.3.2 permits the server to bypass gss authentication checks for certain operations that a client may perform when mounting. In the case of a client that doesn't have some form of credentials available to it on boot, this allows it to perform the mount unattended. (Presumably real file access won't be needed until a user with credentials logs in.) Being slightly more lenient allows lots of old clients to access krb5-only exports, with the only loss being a small amount of information leaked about the root directory of the export. This affects only v2 and v3; v4 still requires authentication for all access. Thanks to Peter Staubach testing against a Solaris client, which suggesting addition of v3 getattr, to the list, and to Trond for noting that doing so exposes no additional information. Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu> Cc: Peter Staubach <staubach@redhat.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Diffstat (limited to 'fs/nfsd/nfsfh.c')
-rw-r--r--fs/nfsd/nfsfh.c30
1 files changed, 20 insertions, 10 deletions
diff --git a/fs/nfsd/nfsfh.c b/fs/nfsd/nfsfh.c
index ea37c96f0445..cd25d91895a1 100644
--- a/fs/nfsd/nfsfh.c
+++ b/fs/nfsd/nfsfh.c
@@ -302,17 +302,27 @@ fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, int type, int access)
if (error)
goto out;
- if (!(access & NFSD_MAY_LOCK)) {
- /*
- * pseudoflavor restrictions are not enforced on NLM,
- * which clients virtually always use auth_sys for,
- * even while using RPCSEC_GSS for NFS.
- */
- error = check_nfsd_access(exp, 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;
+ /*
+ * 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
+ * of rfc 2623.
+ */
+ if (access & NFSD_MAY_BYPASS_GSS_ON_ROOT
+ && exp->ex_path.dentry == dentry)
+ goto skip_pseudoflavor_check;
+
+ error = check_nfsd_access(exp, rqstp);
+ if (error)
+ goto out;
+skip_pseudoflavor_check:
/* Finally, check access permissions. */
error = nfsd_permission(rqstp, exp, dentry, access);