text: // SPDX-License-Identifier: GPL-2.0-only
  #include <linux/types.h>
  #include <linux/sched.h>
  #include <linux/module.h>
  #include <linux/sunrpc/types.h>
  #include <linux/sunrpc/xdr.h>
  #include <linux/sunrpc/svcsock.h>
  #include <linux/sunrpc/svcauth.h>
  #include <linux/sunrpc/gss_api.h>
  #include <linux/sunrpc/addr.h>
  #include <linux/err.h>
  #include <linux/seq_file.h>
  #include <linux/hash.h>
  #include <linux/string.h>
  #include <linux/slab.h>
  #include <net/sock.h>
  #include <net/ipv6.h>
  #include <linux/kernel.h>
  #include <linux/user_namespace.h>
  #define RPCDBG_FACILITY	RPCDBG_AUTH
  
  
  #include "netns.h"
  
  /*
   * AUTHUNIX and AUTHNULL credentials are both handled here.
   * AUTHNULL is treated just like AUTHUNIX except that the uid/gid
   * are always nobody (-2).  i.e. we do the same IP address checks for
   * AUTHNULL as for AUTHUNIX, and that is done here.
   */
  
  
  struct unix_domain {
  	struct auth_domain	h;
  	/* other stuff later */
  };
  
  extern struct auth_ops svcauth_null;
  extern struct auth_ops svcauth_unix;
  
  static void svcauth_unix_domain_release_rcu(struct rcu_head *head)
  {
  	struct auth_domain *dom = container_of(head, struct auth_domain, rcu_head);
  	struct unix_domain *ud = container_of(dom, struct unix_domain, h);
  
  	kfree(dom->name);
  	kfree(ud);
  }
  
  static void svcauth_unix_domain_release(struct auth_domain *dom)
  {
  	call_rcu(&dom->rcu_head, svcauth_unix_domain_release_rcu);
  }
  
  struct auth_domain *unix_domain_find(char *name)
  {
  	struct auth_domain *rv;
  	struct unix_domain *new = NULL;
  
  	rv = auth_domain_find(name);
  	while(1) {
  		if (rv) {
  			if (new && rv != &new->h)
  				svcauth_unix_domain_release(&new->h);
  
  			if (rv->flavour != &svcauth_unix) {
  				auth_domain_put(rv);
  				return NULL;
  			}
  			return rv;
  		}
  
  		new = kmalloc(sizeof(*new), GFP_KERNEL);
  		if (new == NULL)
  			return NULL;
  		kref_init(&new->h.ref);
  		new->h.name = kstrdup(name, GFP_KERNEL);
  		if (new->h.name == NULL) {
  			kfree(new);
  			return NULL;
  		}
  		new->h.flavour = &svcauth_unix;
  		rv = auth_domain_lookup(name, &new->h);
  	}
  }
  EXPORT_SYMBOL_GPL(unix_domain_find);
  
  
  /**************************************************
   * cache for IP address to unix_domain
   * as needed by AUTH_UNIX
   */
  #define	IP_HASHBITS	8
  #define	IP_HASHMAX	(1<<IP_HASHBITS)
  
  struct ip_map {
  	struct cache_head	h;
  	char			m_class[8]; /* e.g. "nfsd" */
  	struct in6_addr		m_addr;
  	struct unix_domain	*m_client;
  	struct rcu_head		m_rcu;
  };
  
  static void ip_map_put(struct kref *kref)
  {
  	struct cache_head *item = container_of(kref, struct cache_head, ref);
  	struct ip_map *im = container_of(item, struct ip_map,h);
  
  	if (test_bit(CACHE_VALID, &item->flags) &&
  	    !test_bit(CACHE_NEGATIVE, &item->flags))
  		auth_domain_put(&im->m_client->h);
  	kfree_rcu(im, m_rcu);
  }
  
  static inline int hash_ip6(const struct in6_addr *ip)
  {
  	return hash_32(ipv6_addr_hash(ip), IP_HASHBITS);
  }
  static int ip_map_match(struct cache_head *corig, struct cache_head *cnew)
  {
  	struct ip_map *orig = container_of(corig, struct ip_map, h);
  	struct ip_map *new = container_of(cnew, struct ip_map, h);
  	return strcmp(orig->m_class, new->m_class) == 0 &&
  	       ipv6_addr_equal(&orig->m_addr, &new->m_addr);
  }
  static void ip_map_init(struct cache_head *cnew, struct cache_head *citem)
  {
  	struct ip_map *new = container_of(cnew, struct ip_map, h);
  	struct ip_map *item = container_of(citem, struct ip_map, h);
  
  	strcpy(new->m_class, item->m_class);
  	new->m_addr = item->m_addr;
  }
  static void update(struct cache_head *cnew, struct cache_head *citem)
  {
  	struct ip_map *new = container_of(cnew, struct ip_map, h);
  	struct ip_map *item = container_of(citem, struct ip_map, h);
  
  	kref_get(&item->m_client->h.ref);
  	new->m_client = item->m_client;
  }
  static struct cache_head *ip_map_alloc(void)
  {
  	struct ip_map *i = kmalloc(sizeof(*i), GFP_KERNEL);
  	if (i)
  		return &i->h;
  	else
  		return NULL;
  }
  
  static int ip_map_upcall(struct cache_detail *cd, struct cache_head *h)
  {
  	return sunrpc_cache_pipe_upcall(cd, h);
  }
  
  static void ip_map_request(struct cache_detail *cd,
  				  struct cache_head *h,
  				  char **bpp, int *blen)
  {
  	char text_addr[40];
  	struct ip_map *im = container_of(h, struct ip_map, h);
  
  	if (ipv6_addr_v4mapped(&(im->m_addr))) {
  		snprintf(text_addr, 20, "%pI4", &im->m_addr.s6_addr32[3]);
  	} else {
  		snprintf(text_addr, 40, "%pI6", &im->m_addr);
  	}
  	qword_add(bpp, blen, im->m_class);
  	qword_add(bpp, blen, text_addr);
  	(*bpp)[-1] = '\n';
  }
  
  static struct ip_map *__ip_map_lookup(struct cache_detail *cd, char *class, struct in6_addr *addr);
  static int __ip_map_update(struct cache_detail *cd, struct ip_map *ipm, struct unix_domain *udom, time64_t expiry);
  
  static int ip_map_parse(struct cache_detail *cd,
  			  char *mesg, int mlen)
  {
  	/* class ipaddress [domainname] */
  	/* should be safe just to use the start of the input buffer
  	 * for scratch: */
  	char *buf = mesg;
  	int len;
  	char class[8];
  	union {
  		struct sockaddr		sa;
  		struct sockaddr_in	s4;
  		struct sockaddr_in6	s6;
  	} address;
  	struct sockaddr_in6 sin6;
  	int err;
  
  	struct ip_map *ipmp;
  	struct auth_domain *dom;
  	time64_t expiry;
  
  	if (mesg[mlen-1] != '\n')
  		return -EINVAL;
  	mesg[mlen-1] = 0;
  
  	/* class */
  	len = qword_get(&mesg, class, sizeof(class));
  	if (len <= 0) return -EINVAL;
  
  	/* ip address */
  	len = qword_get(&mesg, buf, mlen);
  	if (len <= 0) return -EINVAL;
  
  	if (rpc_pton(cd->net, buf, len, &address.sa, sizeof(address)) == 0)
  		return -EINVAL;
  	switch (address.sa.sa_family) {
  	case AF_INET:
  		/* Form a mapped IPv4 address in sin6 */
  		sin6.sin6_family = AF_INET6;
  		ipv6_addr_set_v4mapped(address.s4.sin_addr.s_addr,
  				&sin6.sin6_addr);
  		break;
  #if IS_ENABLED(CONFIG_IPV6)
  	case AF_INET6:
  		memcpy(&sin6, &address.s6, sizeof(sin6));
  		break;
  #endif
  	default:
  		return -EINVAL;
  	}
  
  	expiry = get_expiry(&mesg);
  	if (expiry ==0)
  		return -EINVAL;
  
  	/* domainname, or empty for NEGATIVE */
  	len = qword_get(&mesg, buf, mlen);
  	if (len < 0) return -EINVAL;
  
  	if (len) {
  		dom = unix_domain_find(buf);
  		if (dom == NULL)
  			return -ENOENT;
  	} else
  		dom = NULL;
  
  	/* IPv6 scope IDs are ignored for now */
  	ipmp = __ip_map_lookup(cd, class, &sin6.sin6_addr);
  	if (ipmp) {
  		err = __ip_map_update(cd, ipmp,
  			     container_of(dom, struct unix_domain, h),
  			     expiry);
  	} else
  		err = -ENOMEM;
  
  	if (dom)
  		auth_domain_put(dom);
  
  	cache_flush();
  	return err;
  }
  
  static int ip_map_show(struct seq_file *m,
  		       struct cache_detail *cd,
  		       struct cache_head *h)
  {
  	struct ip_map *im;
  	struct in6_addr addr;
  	char *dom = "-no-domain-";
  
  	if (h == NULL) {
  		seq_puts(m, "#class IP domain\n");
  		return 0;
  	}
  	im = container_of(h, struct ip_map, h);
  	/* class addr domain */
  	addr = im->m_addr;
  
  	if (test_bit(CACHE_VALID, &h->flags) &&
  	    !test_bit(CACHE_NEGATIVE, &h->flags))
  		dom = im->m_client->h.name;
  
  	if (ipv6_addr_v4mapped(&addr)) {
  		seq_printf(m, "%s %pI4 %s\n",
  			im->m_class, &addr.s6_addr32[3], dom);
  	} else {
  		seq_printf(m, "%s %pI6 %s\n", im->m_class, &addr, dom);
  	}
  	return 0;
  }
  
  
  static struct ip_map *__ip_map_lookup(struct cache_detail *cd, char *class,
  		struct in6_addr *addr)
  {
  	struct ip_map ip;
  	struct cache_head *ch;
  
  	strcpy(ip.m_class, class);
  	ip.m_addr = *addr;
  	ch = sunrpc_cache_lookup_rcu(cd, &ip.h,
  				     hash_str(class, IP_HASHBITS) ^
  				     hash_ip6(addr));
  
  	if (ch)
  		return container_of(ch, struct ip_map, h);
  	else
  		return NULL;
  }
  
  static int __ip_map_update(struct cache_detail *cd, struct ip_map *ipm,
  		struct unix_domain *udom, time64_t expiry)
  {
  	struct ip_map ip;
  	struct cache_head *ch;
  
  	ip.m_client = udom;
  	ip.h.flags = 0;
  	if (!udom)
  		set_bit(CACHE_NEGATIVE, &ip.h.flags);
  	ip.h.expiry_time = expiry;
  	ch = sunrpc_cache_update(cd, &ip.h, &ipm->h,
  				 hash_str(ipm->m_class, IP_HASHBITS) ^
  				 hash_ip6(&ipm->m_addr));
  	if (!ch)
  		return -ENOMEM;
  	cache_put(ch, cd);
  	return 0;
  }
  
  void svcauth_unix_purge(struct net *net)
  {
  	struct sunrpc_net *sn;
  
  	sn = net_generic(net, sunrpc_net_id);
  	cache_purge(sn->ip_map_cache);
  }
  EXPORT_SYMBOL_GPL(svcauth_unix_purge);
  
  static inline struct ip_map *
  ip_map_cached_get(struct svc_xprt *xprt)
  {
  	struct ip_map *ipm = NULL;
  	struct sunrpc_net *sn;
  
  	if (test_bit(XPT_CACHE_AUTH, &xprt->xpt_flags)) {
  		spin_lock(&xprt->xpt_lock);
  		ipm = xprt->xpt_auth_cache;
  		if (ipm != NULL) {
  			sn = net_generic(xprt->xpt_net, sunrpc_net_id);
  			if (cache_is_expired(sn->ip_map_cache, &ipm->h)) {
  				/*
  				 * The entry has been invalidated since it was
  				 * remembered, e.g. by a second mount from the
  				 * same IP address.
  				 */
  				xprt->xpt_auth_cache = NULL;
  				spin_unlock(&xprt->xpt_lock);
  				cache_put(&ipm->h, sn->ip_map_cache);
  				return NULL;
  			}
  			cache_get(&ipm->h);
  		}
  		spin_unlock(&xprt->xpt_lock);
  	}
  	return ipm;
  }
  
  static inline void
  ip_map_cached_put(struct svc_xprt *xprt, struct ip_map *ipm)
  {
  	if (test_bit(XPT_CACHE_AUTH, &xprt->xpt_flags)) {
  		spin_lock(&xprt->xpt_lock);
  		if (xprt->xpt_auth_cache == NULL) {
  			/* newly cached, keep the reference */
  			xprt->xpt_auth_cache = ipm;
  			ipm = NULL;
  		}
  		spin_unlock(&xprt->xpt_lock);
  	}
  	if (ipm) {
  		struct sunrpc_net *sn;
  
  		sn = net_generic(xprt->xpt_net, sunrpc_net_id);
  		cache_put(&ipm->h, sn->ip_map_cache);
  	}
  }
  
  void
  svcauth_unix_info_release(struct svc_xprt *xpt)
  {
  	struct ip_map *ipm;
  
  	ipm = xpt->xpt_auth_cache;
  	if (ipm != NULL) {
  		struct sunrpc_net *sn;
  
  		sn = net_generic(xpt->xpt_net, sunrpc_net_id);
  		cache_put(&ipm->h, sn->ip_map_cache);
  	}
  }
  
  /****************************************************************************
   * auth.unix.gid cache
   * simple cache to map a UID to a list of GIDs
   * because AUTH_UNIX aka AUTH_SYS has a max of UNX_NGROUPS
   */
  #define	GID_HASHBITS	8
  #define	GID_HASHMAX	(1<<GID_HASHBITS)
  
  struct unix_gid {
  	struct cache_head	h;
  	kuid_t			uid;
  	struct group_info	*gi;
  	struct rcu_head		rcu;
  };
  
  static int unix_gid_hash(kuid_t uid)
  {
  	return hash_long(from_kuid(&init_user_ns, uid), GID_HASHBITS);
  }
  
  static void unix_gid_put(struct kref *kref)
  {
  	struct cache_head *item = container_of(kref, struct cache_head, ref);
  	struct unix_gid *ug = container_of(item, struct unix_gid, h);
  	if (test_bit(CACHE_VALID, &item->flags) &&
  	    !test_bit(CACHE_NEGATIVE, &item->flags))
  		put_group_info(ug->gi);
  	kfree_rcu(ug, rcu);
  }
  
  static int unix_gid_match(struct cache_head *corig, struct cache_head *cnew)
  {
  	struct unix_gid *orig = container_of(corig, struct unix_gid, h);
  	struct unix_gid *new = container_of(cnew, struct unix_gid, h);
  	return uid_eq(orig->uid, new->uid);
  }
  static void unix_gid_init(struct cache_head *cnew, struct cache_head *citem)
  {
  	struct unix_gid *new = container_of(cnew, struct unix_gid, h);
  	struct unix_gid *item = container_of(citem, struct unix_gid, h);
  	new->uid = item->uid;
  }
  static void unix_gid_update(struct cache_head *cnew, struct cache_head *citem)
  {
  	struct unix_gid *new = container_of(cnew, struct unix_gid, h);
  	struct unix_gid *item = container_of(citem, struct unix_gid, h);
  
  	get_group_info(item->gi);
  	new->gi = item->gi;
  }
  static struct cache_head *unix_gid_alloc(void)
  {
  	struct unix_gid *g = kmalloc(sizeof(*g), GFP_KERNEL);
  	if (g)
  		return &g->h;
  	else
  		return NULL;
  }
  
  static int unix_gid_upcall(struct cache_detail *cd, struct cache_head *h)
  {
  	return sunrpc_cache_pipe_upcall_timeout(cd, h);
  }
  
  static void unix_gid_request(struct cache_detail *cd,
  			     struct cache_head *h,
  			     char **bpp, int *blen)
  {
  	char tuid[20];
  	struct unix_gid *ug = container_of(h, struct unix_gid, h);
  
  	snprintf(tuid, 20, "%u", from_kuid(&init_user_ns, ug->uid));
  	qword_add(bpp, blen, tuid);
  	(*bpp)[-1] = '\n';
  }
  
  static struct unix_gid *unix_gid_lookup(struct cache_detail *cd, kuid_t uid);
  
  static int unix_gid_parse(struct cache_detail *cd,
  			char *mesg, int mlen)
  {
  	/* uid expiry Ngid gid0 gid1 ... gidN-1 */
  	int id;
  	kuid_t uid;
  	int gids;
  	int rv;
  	int i;
  	int err;
  	time64_t expiry;
  	struct unix_gid ug, *ugp;
  
  	if (mesg[mlen - 1] != '\n')
  		return -EINVAL;
  	mesg[mlen-1] = 0;
  
  	rv = get_int(&mesg, &id);
  	if (rv)
  		return -EINVAL;
  	uid = make_kuid(current_user_ns(), id);
  	ug.uid = uid;
  
  	expiry = get_expiry(&mesg);
  	if (expiry == 0)
  		return -EINVAL;
  
  	rv = get_int(&mesg, &gids);
  	if (rv || gids < 0 || gids > 8192)
  		return -EINVAL;
  
  	ug.gi = groups_alloc(gids);
  	if (!ug.gi)
  		return -ENOMEM;
  
  	for (i = 0 ; i < gids ; i++) {
  		int gid;
  		kgid_t kgid;
  		rv = get_int(&mesg, &gid);
  		err = -EINVAL;
  		if (rv)
  			goto out;
  		kgid = make_kgid(current_user_ns(), gid);
  		if (!gid_valid(kgid))
  			goto out;
  		ug.gi->gid[i] = kgid;
  	}
  
  	groups_sort(ug.gi);
  	ugp = unix_gid_lookup(cd, uid);
  	if (ugp) {
  		struct cache_head *ch;
  		ug.h.flags = 0;
  		ug.h.expiry_time = expiry;
  		ch = sunrpc_cache_update(cd,
  					 &ug.h, &ugp->h,
  					 unix_gid_hash(uid));
  		if (!ch)
  			err = -ENOMEM;
  		else {
  			err = 0;
  			cache_put(ch, cd);
  		}
  	} else
  		err = -ENOMEM;
   out:
  	if (ug.gi)
  		put_group_info(ug.gi);
  	return err;
  }
  
  static int unix_gid_show(struct seq_file *m,
  			 struct cache_detail *cd,
  			 struct cache_head *h)
  {
  	struct user_namespace *user_ns = m->file->f_cred->user_ns;
  	struct unix_gid *ug;
  	int i;
  	int glen;
  
  	if (h == NULL) {
  		seq_puts(m, "#uid cnt: gids...\n");
  		return 0;
  	}
  	ug = container_of(h, struct unix_gid, h);
  	if (test_bit(CACHE_VALID, &h->flags) &&
  	    !test_bit(CACHE_NEGATIVE, &h->flags))
  		glen = ug->gi->ngroups;
  	else
  		glen = 0;
  
  	seq_printf(m, "%u %d:", from_kuid_munged(user_ns, ug->uid), glen);
  	for (i = 0; i < glen; i++)
  		seq_printf(m, " %d", from_kgid_munged(user_ns, ug->gi->gid[i]));
  	seq_printf(m, "\n");
  	return 0;
  }
  
  static const struct cache_detail unix_gid_cache_template = {
  	.owner		= THIS_MODULE,
  	.hash_size	= GID_HASHMAX,
  	.name		= "auth.unix.gid",
  	.cache_put	= unix_gid_put,
  	.cache_upcall	= unix_gid_upcall,
  	.cache_request	= unix_gid_request,
  	.cache_parse	= unix_gid_parse,
  	.cache_show	= unix_gid_show,
  	.match		= unix_gid_match,
  	.init		= unix_gid_init,
  	.update		= unix_gid_update,
  	.alloc		= unix_gid_alloc,
  };
  
  int unix_gid_cache_create(struct net *net)
  {
  	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
  	struct cache_detail *cd;
  	int err;
  
  	cd = cache_create_net(&unix_gid_cache_template, net);
  	if (IS_ERR(cd))
  		return PTR_ERR(cd);
  	err = cache_register_net(cd, net);
  	if (err) {
  		cache_destroy_net(cd, net);
  		return err;
  	}
  	sn->unix_gid_cache = cd;
  	return 0;
  }
  
  void unix_gid_cache_destroy(struct net *net)
  {
  	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
  	struct cache_detail *cd = sn->unix_gid_cache;
  
  	sn->unix_gid_cache = NULL;
  	cache_purge(cd);
  	cache_unregister_net(cd, net);
  	cache_destroy_net(cd, net);
  }
  
  static struct unix_gid *unix_gid_lookup(struct cache_detail *cd, kuid_t uid)
  {
  	struct unix_gid ug;
  	struct cache_head *ch;
  
  	ug.uid = uid;
  	ch = sunrpc_cache_lookup_rcu(cd, &ug.h, unix_gid_hash(uid));
  	if (ch)
  		return container_of(ch, struct unix_gid, h);
  	else
  		return NULL;
  }
  
  static struct group_info *unix_gid_find(kuid_t uid, struct svc_rqst *rqstp)
  {
  	struct unix_gid *ug;
  	struct group_info *gi;
  	int ret;
  	struct sunrpc_net *sn = net_generic(rqstp->rq_xprt->xpt_net,
  					    sunrpc_net_id);
  
  	ug = unix_gid_lookup(sn->unix_gid_cache, uid);
  	if (!ug)
  		return ERR_PTR(-EAGAIN);
  	ret = cache_check(sn->unix_gid_cache, &ug->h, &rqstp->rq_chandle);
  	switch (ret) {
  	case -ENOENT:
  		return ERR_PTR(-ENOENT);
  	case -ETIMEDOUT:
  		return ERR_PTR(-ESHUTDOWN);
  	case 0:
  		gi = get_group_info(ug->gi);
  		cache_put(&ug->h, sn->unix_gid_cache);
  		return gi;
  	default:
  		return ERR_PTR(-EAGAIN);
  	}
  }
  
  int
  svcauth_unix_set_client(struct svc_rqst *rqstp)
  {
  	struct sockaddr_in *sin;
  	struct sockaddr_in6 *sin6, sin6_storage;
  	struct ip_map *ipm;
  	struct group_info *gi;
  	struct svc_cred *cred = &rqstp->rq_cred;
  	struct svc_xprt *xprt = rqstp->rq_xprt;
  	struct net *net = xprt->xpt_net;
  	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
  
  	switch (rqstp->rq_addr.ss_family) {
  	case AF_INET:
  		sin = svc_addr_in(rqstp);
  		sin6 = &sin6_storage;
  		ipv6_addr_set_v4mapped(sin->sin_addr.s_addr, &sin6->sin6_addr);
  		break;
  	case AF_INET6:
  		sin6 = svc_addr_in6(rqstp);
  		break;
  	default:
  		BUG();
  	}
  
  	rqstp->rq_client = NULL;
  	if (rqstp->rq_proc == 0)
  		return SVC_OK;
  
  	ipm = ip_map_cached_get(xprt);
  	if (ipm == NULL)
  		ipm = __ip_map_lookup(sn->ip_map_cache, rqstp->rq_server->sv_program->pg_class,
  				    &sin6->sin6_addr);
  
  	if (ipm == NULL)
  		return SVC_DENIED;
  
  	switch (cache_check(sn->ip_map_cache, &ipm->h, &rqstp->rq_chandle)) {
  		default:
  			BUG();
  		case -ETIMEDOUT:
  			return SVC_CLOSE;
  		case -EAGAIN:
  			return SVC_DROP;
  		case -ENOENT:
  			return SVC_DENIED;
  		case 0:
  			rqstp->rq_client = &ipm->m_client->h;
  			kref_get(&rqstp->rq_client->ref);
  			ip_map_cached_put(xprt, ipm);
  			break;
  	}
  
  	gi = unix_gid_find(cred->cr_uid, rqstp);
  	switch (PTR_ERR(gi)) {
  	case -EAGAIN:
  		return SVC_DROP;
  	case -ESHUTDOWN:
  		return SVC_CLOSE;
  	case -ENOENT:
  		break;
  	default:
  		put_group_info(cred->cr_group_info);
  		cred->cr_group_info = gi;
  	}
  	return SVC_OK;
  }
  
  EXPORT_SYMBOL_GPL(svcauth_unix_set_client);
  
  static int
  svcauth_null_accept(struct svc_rqst *rqstp, __be32 *authp)
  {
  	struct kvec	*argv = &rqstp->rq_arg.head[0];
  	struct kvec	*resv = &rqstp->rq_res.head[0];
  	struct svc_cred	*cred = &rqstp->rq_cred;
  
  	if (argv->iov_len < 3*4)
  		return SVC_GARBAGE;
  
  	if (svc_getu32(argv) != 0) {
  		dprintk("svc: bad null cred\n");
  		*authp = rpc_autherr_badcred;
  		return SVC_DENIED;
  	}
  	if (svc_getu32(argv) != htonl(RPC_AUTH_NULL) || svc_getu32(argv) != 0) {
  		dprintk("svc: bad null verf\n");
  		*authp = rpc_autherr_badverf;
  		return SVC_DENIED;
  	}
  
  	/* Signal that mapping to nobody uid/gid is required */
  	cred->cr_uid = INVALID_UID;
  	cred->cr_gid = INVALID_GID;
  	cred->cr_group_info = groups_alloc(0);
  	if (cred->cr_group_info == NULL)
  		return SVC_CLOSE; /* kmalloc failure - client must retry */
  
  	/* Put NULL verifier */
  	svc_putnl(resv, RPC_AUTH_NULL);
  	svc_putnl(resv, 0);
  
  	rqstp->rq_cred.cr_flavor = RPC_AUTH_NULL;
  	return SVC_OK;
  }
  
  static int
  svcauth_null_release(struct svc_rqst *rqstp)
  {
  	if (rqstp->rq_client)
  		auth_domain_put(rqstp->rq_client);
  	rqstp->rq_client = NULL;
  	if (rqstp->rq_cred.cr_group_info)
  		put_group_info(rqstp->rq_cred.cr_group_info);
  	rqstp->rq_cred.cr_group_info = NULL;
  
  	return 0; /* don't drop */
  }
  
  
  struct auth_ops svcauth_null = {
  	.name		= "null",
  	.owner		= THIS_MODULE,
  	.flavour	= RPC_AUTH_NULL,
  	.accept 	= svcauth_null_accept,
  	.release	= svcauth_null_release,
  	.set_client	= svcauth_unix_set_client,
  };
  
  
  static int
  svcauth_unix_accept(struct svc_rqst *rqstp, __be32 *authp)
  {
  	struct kvec	*argv = &rqstp->rq_arg.head[0];
  	struct kvec	*resv = &rqstp->rq_res.head[0];
  	struct svc_cred	*cred = &rqstp->rq_cred;
  	struct user_namespace *userns;
  	u32		slen, i;
  	int		len   = argv->iov_len;
  
  	if ((len -= 3*4) < 0)
  		return SVC_GARBAGE;
  
  	svc_getu32(argv);			/* length */
  	svc_getu32(argv);			/* time stamp */
  	slen = XDR_QUADLEN(svc_getnl(argv));	/* machname length */
  	if (slen > 64 || (len -= (slen + 3)*4) < 0)
  		goto badcred;
  	argv->iov_base = (void*)((__be32*)argv->iov_base + slen);	/* skip machname */
  	argv->iov_len -= slen*4;
  	/*
  	 * Note: we skip uid_valid()/gid_valid() checks here for
  	 * backwards compatibility with clients that use -1 id's.
  	 * Instead, -1 uid or gid is later mapped to the
  	 * (export-specific) anonymous id by nfsd_setuser.
  	 * Supplementary gid's will be left alone.
  	 */
  	userns = (rqstp->rq_xprt && rqstp->rq_xprt->xpt_cred) ?
  		rqstp->rq_xprt->xpt_cred->user_ns : &init_user_ns;
  	cred->cr_uid = make_kuid(userns, svc_getnl(argv)); /* uid */
  	cred->cr_gid = make_kgid(userns, svc_getnl(argv)); /* gid */
  	slen = svc_getnl(argv);			/* gids length */
  	if (slen > UNX_NGROUPS || (len -= (slen + 2)*4) < 0)
  		goto badcred;
  	cred->cr_group_info = groups_alloc(slen);
  	if (cred->cr_group_info == NULL)
  		return SVC_CLOSE;
  	for (i = 0; i < slen; i++) {
  		kgid_t kgid = make_kgid(userns, svc_getnl(argv));
  		cred->cr_group_info->gid[i] = kgid;
  	}
  	groups_sort(cred->cr_group_info);
  	if (svc_getu32(argv) != htonl(RPC_AUTH_NULL) || svc_getu32(argv) != 0) {
  		*authp = rpc_autherr_badverf;
  		return SVC_DENIED;
  	}
  
  	/* Put NULL verifier */
  	svc_putnl(resv, RPC_AUTH_NULL);
  	svc_putnl(resv, 0);
  
  	rqstp->rq_cred.cr_flavor = RPC_AUTH_UNIX;
  	return SVC_OK;
  
  badcred:
  	*authp = rpc_autherr_badcred;
  	return SVC_DENIED;
  }
  
  static int
  svcauth_unix_release(struct svc_rqst *rqstp)
  {
  	/* Verifier (such as it is) is already in place.
  	 */
  	if (rqstp->rq_client)
  		auth_domain_put(rqstp->rq_client);
  	rqstp->rq_client = NULL;
  	if (rqstp->rq_cred.cr_group_info)
  		put_group_info(rqstp->rq_cred.cr_group_info);
  	rqstp->rq_cred.cr_group_info = NULL;
  
  	return 0;
  }
  
  
  struct auth_ops svcauth_unix = {
  	.name		= "unix",
  	.owner		= THIS_MODULE,
  	.flavour	= RPC_AUTH_UNIX,
  	.accept 	= svcauth_unix_accept,
  	.release	= svcauth_unix_release,
  	.domain_release	= svcauth_unix_domain_release,
  	.set_client	= svcauth_unix_set_client,
  };
  
  static const struct cache_detail ip_map_cache_template = {
  	.owner		= THIS_MODULE,
  	.hash_size	= IP_HASHMAX,
  	.name		= "auth.unix.ip",
  	.cache_put	= ip_map_put,
  	.cache_upcall	= ip_map_upcall,
  	.cache_request	= ip_map_request,
  	.cache_parse	= ip_map_parse,
  	.cache_show	= ip_map_show,
  	.match		= ip_map_match,
  	.init		= ip_map_init,
  	.update		= update,
  	.alloc		= ip_map_alloc,
  };
  
  int ip_map_cache_create(struct net *net)
  {
  	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
  	struct cache_detail *cd;
  	int err;
  
  	cd = cache_create_net(&ip_map_cache_template, net);
  	if (IS_ERR(cd))
  		return PTR_ERR(cd);
  	err = cache_register_net(cd, net);
  	if (err) {
  		cache_destroy_net(cd, net);
  		return err;
  	}
  	sn->ip_map_cache = cd;
  	return 0;
  }
  
  void ip_map_cache_destroy(struct net *net)
  {
  	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
  	struct cache_detail *cd = sn->ip_map_cache;
  
  	sn->ip_map_cache = NULL;
  	cache_purge(cd);
  	cache_unregister_net(cd, net);
  	cache_destroy_net(cd, net);
  }
  