// SPDX-License-Identifier: GPL-2.0

  /* Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de> */

  #include <linux/sched.h>

  #include "nfsd.h"

  #include "auth.h"

  int nfsexp_flags(struct svc_rqst *rqstp, struct svc_export *exp)

  {
  	struct exp_flavor_info *f;
  	struct exp_flavor_info *end = exp->ex_flavors + exp->ex_nflavors;
  
  	for (f = exp->ex_flavors; f < end; f++) {

  		if (f->pseudoflavor == rqstp->rq_cred.cr_flavor)

  			return f->flags;
  	}
  	return exp->ex_flags;
  
  }

  int nfsd_setuser(struct svc_rqst *rqstp, struct svc_export *exp)
  {

  	struct group_info *rqgi;
  	struct group_info *gi;
  	struct cred *new;

  	int i;

  	int flags = nfsexp_flags(rqstp, exp);

  	validate_process_creds();

  	/* discard any old override before preparing the new set */

  	revert_creds(get_cred(current_real_cred()));

  	new = prepare_creds();
  	if (!new)
  		return -ENOMEM;
  
  	new->fsuid = rqstp->rq_cred.cr_uid;
  	new->fsgid = rqstp->rq_cred.cr_gid;
  
  	rqgi = rqstp->rq_cred.cr_group_info;

  	if (flags & NFSEXP_ALLSQUASH) {

  		new->fsuid = exp->ex_anon_uid;
  		new->fsgid = exp->ex_anon_gid;
  		gi = groups_alloc(0);

  		if (!gi)
  			goto oom;

  	} else if (flags & NFSEXP_ROOTSQUASH) {

  		if (uid_eq(new->fsuid, GLOBAL_ROOT_UID))

  			new->fsuid = exp->ex_anon_uid;

  		if (gid_eq(new->fsgid, GLOBAL_ROOT_GID))

  			new->fsgid = exp->ex_anon_gid;

  		gi = groups_alloc(rqgi->ngroups);
  		if (!gi)
  			goto oom;
  
  		for (i = 0; i < rqgi->ngroups; i++) {

  			if (gid_eq(GLOBAL_ROOT_GID, rqgi->gid[i]))
  				gi->gid[i] = exp->ex_anon_gid;

  			else

  				gi->gid[i] = rqgi->gid[i];

  		}

  
  		/* Each thread allocates its own gi, no race */
  		groups_sort(gi);

  	} else {

  		gi = get_group_info(rqgi);

  	}

  	if (uid_eq(new->fsuid, INVALID_UID))

  		new->fsuid = exp->ex_anon_uid;

  	if (gid_eq(new->fsgid, INVALID_GID))

  		new->fsgid = exp->ex_anon_gid;

  	set_groups(new, gi);

  	put_group_info(gi);

  	if (!uid_eq(new->fsuid, GLOBAL_ROOT_UID))

  		new->cap_effective = cap_drop_nfsd_set(new->cap_effective);
  	else
  		new->cap_effective = cap_raise_nfsd_set(new->cap_effective,
  							new->cap_permitted);

  	validate_process_creds();

  	put_cred(override_creds(new));

  	put_cred(new);

  	validate_process_creds();

  	return 0;

  
  oom:

  	abort_creds(new);

  	return -ENOMEM;

  }