// 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_cred *cred, 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 == cred->cr_flavor)
                        return f->flags;
        }
        return exp->ex_flags;

}

int nfsd_setuser(struct svc_cred *cred, struct svc_export *exp)
{
        struct group_info *rqgi;
        struct group_info *gi;
        struct cred *new;
        int i;
        int flags = nfsexp_flags(cred, exp);

        /* discard any old override before preparing the new set */
        put_cred(revert_creds(get_cred(current_real_cred())));
        new = prepare_creds();
        if (!new)
                return -ENOMEM;

        new->fsuid = cred->cr_uid;
        new->fsgid = cred->cr_gid;

        rqgi = 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);
        put_cred(override_creds(new));
        return 0;

oom:
        abort_creds(new);
        return -ENOMEM;
}