Bug 168335

While accessing nfs shares exported with NFSv4 sec=krb5i,
no other export types,
vfs.nfsd.server_max_nfsvers: 4
vfs.nfsd.server_min_nfsvers: 4

access rights to be provided by some groups are not granted (permission denied).
A test reveals it to be the case with the groups not within the first 16 ones in the output of "id [-G] <account>" command (on the server).

A quick glance at the source suggests that it may have to do with

fs/nfs/rpcv2.h:#define    RPCAUTH_UNIXGIDS 16

which is being used in

./../rpc/rpcsec_gss/svc_rpcsec_gss.c:  gid_t cl_gid_storage[RPCAUTH_UNIXGIDS];
./../rpc/rpcsec_gss/svc_rpcsec_gss.c:  numgroups = RPCAUTH_UNIXGIDS;

This problem is a showstopper for a deployment (migrating from a *Solaris server) as we are using groups very extensively.

Regards,
Rune

How-To-Repeat: put an account in more than 16 unix groups
export a share over NFSv4 sec=krb5i  (well, any krb*)
create a directory not owned by the account, chgrp to the account's group with a highest gid (or otherwise "one of the later groups on its list"), chmod 770

access the share (e.g. from a RHEL5.6 Linux client) with the Kerberos credentials of the corresponding account

ls -ld <the-directory>   shows owner,group and the rwxrwx--- permissions
ls -l <the-directory>    yields "permission denied"

Note that the same test passes (no "permission denied") against both Solaris and Linux NFSv4 servers with the same Kerberos realm, passwd/group database, accounts and client hosts.