net/sunrpc/auth_gss/gss_mech_switch.c - linux - Git at Google

 // SPDX-License-Identifier: BSD-3-Clause
 /*
  *  linux/net/sunrpc/gss_mech_switch.c
  *
  *  Copyright (c) 2001 The Regents of the University of Michigan.
  *  All rights reserved.
  *
  *  J. Bruce Fields   <bfields@umich.edu>
  */

 #include <linux/types.h>
 #include <linux/slab.h>
 #include <linux/module.h>
 #include <linux/oid_registry.h>
 #include <linux/sunrpc/msg_prot.h>
 #include <linux/sunrpc/gss_asn1.h>
 #include <linux/sunrpc/auth_gss.h>
 #include <linux/sunrpc/svcauth_gss.h>
 #include <linux/sunrpc/gss_err.h>
 #include <linux/sunrpc/sched.h>
 #include <linux/sunrpc/gss_api.h>
 #include <linux/sunrpc/clnt.h>
 #include <trace/events/rpcgss.h>

 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
 # define RPCDBG_FACILITY        RPCDBG_AUTH
 #endif

 static LIST_HEAD(registered_mechs);
 static DEFINE_SPINLOCK(registered_mechs_lock);

 static void
 gss_mech_free(struct gss_api_mech *gm)
 {
 	struct pf_desc *pf;
 	int i;

 	for (i = 0; i < gm->gm_pf_num; i++) {
 		pf = &gm->gm_pfs[i];
 		if (pf->domain)
 			auth_domain_put(pf->domain);
 		kfree(pf->auth_domain_name);
 		pf->auth_domain_name = NULL;
 	}
 }

 static inline char *
 make_auth_domain_name(char *name)
 {
 	static char	*prefix = "gss/";
 	char		*new;

 	new = kmalloc(strlen(name) + strlen(prefix) + 1, GFP_KERNEL);
 	if (new) {
 		strcpy(new, prefix);
 		strcat(new, name);
 	}
 	return new;
 }

 static int
 gss_mech_svc_setup(struct gss_api_mech *gm)
 {
 	struct auth_domain *dom;
 	struct pf_desc *pf;
 	int i, status;

 	for (i = 0; i < gm->gm_pf_num; i++) {
 		pf = &gm->gm_pfs[i];
 		pf->auth_domain_name = make_auth_domain_name(pf->name);
 		status = -ENOMEM;
 		if (pf->auth_domain_name == NULL)
 			goto out;
 		dom = svcauth_gss_register_pseudoflavor(
 			pf->pseudoflavor, pf->auth_domain_name);
 		if (IS_ERR(dom)) {
 			status = PTR_ERR(dom);
 			goto out;
 		}
 		pf->domain = dom;
 	}
 	return 0;
 out:
 	gss_mech_free(gm);
 	return status;
 }

 /**
  * gss_mech_register - register a GSS mechanism
  * @gm: GSS mechanism handle
  *
  * Returns zero if successful, or a negative errno.
  */
 int gss_mech_register(struct gss_api_mech *gm)
 {
 	int status;

 	status = gss_mech_svc_setup(gm);
 	if (status)
 		return status;
 	spin_lock(&registered_mechs_lock);
 	list_add_rcu(&gm->gm_list, &registered_mechs);
 	spin_unlock(&registered_mechs_lock);
 	dprintk("RPC:       registered gss mechanism %s\n", gm->gm_name);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(gss_mech_register);

 /**
  * gss_mech_unregister - release a GSS mechanism
  * @gm: GSS mechanism handle
  *
  */
 void gss_mech_unregister(struct gss_api_mech *gm)
 {
 	spin_lock(&registered_mechs_lock);
 	list_del_rcu(&gm->gm_list);
 	spin_unlock(&registered_mechs_lock);
 	dprintk("RPC:       unregistered gss mechanism %s\n", gm->gm_name);
 	gss_mech_free(gm);
 }
 EXPORT_SYMBOL_GPL(gss_mech_unregister);

 struct gss_api_mech *gss_mech_get(struct gss_api_mech *gm)
 {
 	__module_get(gm->gm_owner);
 	return gm;
 }
 EXPORT_SYMBOL(gss_mech_get);

 static struct gss_api_mech *
 _gss_mech_get_by_name(const char *name)
 {
 	struct gss_api_mech	*pos, *gm = NULL;

 	rcu_read_lock();
 	list_for_each_entry_rcu(pos, &registered_mechs, gm_list) {
 		if (0 == strcmp(name, pos->gm_name)) {
 			if (try_module_get(pos->gm_owner))
 				gm = pos;
 			break;
 		}
 	}
 	rcu_read_unlock();
 	return gm;

 }

 struct gss_api_mech * gss_mech_get_by_name(const char *name)
 {
 	struct gss_api_mech *gm = NULL;

 	gm = _gss_mech_get_by_name(name);
 	if (!gm) {
 		request_module("rpc-auth-gss-%s", name);
 		gm = _gss_mech_get_by_name(name);
 	}
 	return gm;
 }

 struct gss_api_mech *gss_mech_get_by_OID(struct rpcsec_gss_oid *obj)
 {
 	struct gss_api_mech	*pos, *gm = NULL;
 	char buf[32];

 	if (sprint_oid(obj->data, obj->len, buf, sizeof(buf)) < 0)
 		return NULL;
 	request_module("rpc-auth-gss-%s", buf);

 	rcu_read_lock();
 	list_for_each_entry_rcu(pos, &registered_mechs, gm_list) {
 		if (obj->len == pos->gm_oid.len) {
 			if (0 == memcmp(obj->data, pos->gm_oid.data, obj->len)) {
 				if (try_module_get(pos->gm_owner))
 					gm = pos;
 				break;
 			}
 		}
 	}
 	rcu_read_unlock();
 	if (!gm)
 		trace_rpcgss_oid_to_mech(buf);
 	return gm;
 }

 static inline int
 mech_supports_pseudoflavor(struct gss_api_mech *gm, u32 pseudoflavor)
 {
 	int i;

 	for (i = 0; i < gm->gm_pf_num; i++) {
 		if (gm->gm_pfs[i].pseudoflavor == pseudoflavor)
 			return 1;
 	}
 	return 0;
 }

 static struct gss_api_mech *_gss_mech_get_by_pseudoflavor(u32 pseudoflavor)
 {
 	struct gss_api_mech *gm = NULL, *pos;

 	rcu_read_lock();
 	list_for_each_entry_rcu(pos, &registered_mechs, gm_list) {
 		if (!mech_supports_pseudoflavor(pos, pseudoflavor))
 			continue;
 		if (try_module_get(pos->gm_owner))
 			gm = pos;
 		break;
 	}
 	rcu_read_unlock();
 	return gm;
 }

 struct gss_api_mech *
 gss_mech_get_by_pseudoflavor(u32 pseudoflavor)
 {
 	struct gss_api_mech *gm;

 	gm = _gss_mech_get_by_pseudoflavor(pseudoflavor);

 	if (!gm) {
 		request_module("rpc-auth-gss-%u", pseudoflavor);
 		gm = _gss_mech_get_by_pseudoflavor(pseudoflavor);
 	}
 	return gm;
 }

 /**
  * gss_svc_to_pseudoflavor - map a GSS service number to a pseudoflavor
  * @gm: GSS mechanism handle
  * @qop: GSS quality-of-protection value
  * @service: GSS service value
  *
  * Returns a matching security flavor, or RPC_AUTH_MAXFLAVOR if none is found.
  */
 rpc_authflavor_t gss_svc_to_pseudoflavor(struct gss_api_mech *gm, u32 qop,
 					 u32 service)
 {
 	int i;

 	for (i = 0; i < gm->gm_pf_num; i++) {
 		if (gm->gm_pfs[i].qop == qop &&
 		    gm->gm_pfs[i].service == service) {
 			return gm->gm_pfs[i].pseudoflavor;
 		}
 	}
 	return RPC_AUTH_MAXFLAVOR;
 }

 /**
  * gss_mech_info2flavor - look up a pseudoflavor given a GSS tuple
  * @info: a GSS mech OID, quality of protection, and service value
  *
  * Returns a matching pseudoflavor, or RPC_AUTH_MAXFLAVOR if the tuple is
  * not supported.
  */
 rpc_authflavor_t gss_mech_info2flavor(struct rpcsec_gss_info *info)
 {
 	rpc_authflavor_t pseudoflavor;
 	struct gss_api_mech *gm;

 	gm = gss_mech_get_by_OID(&info->oid);
 	if (gm == NULL)
 		return RPC_AUTH_MAXFLAVOR;

 	pseudoflavor = gss_svc_to_pseudoflavor(gm, info->qop, info->service);

 	gss_mech_put(gm);
 	return pseudoflavor;
 }

 /**
  * gss_mech_flavor2info - look up a GSS tuple for a given pseudoflavor
  * @pseudoflavor: GSS pseudoflavor to match
  * @info: rpcsec_gss_info structure to fill in
  *
  * Returns zero and fills in "info" if pseudoflavor matches a
  * supported mechanism.  Otherwise a negative errno is returned.
  */
 int gss_mech_flavor2info(rpc_authflavor_t pseudoflavor,
 			 struct rpcsec_gss_info *info)
 {
 	struct gss_api_mech *gm;
 	int i;

 	gm = gss_mech_get_by_pseudoflavor(pseudoflavor);
 	if (gm == NULL)
 		return -ENOENT;

 	for (i = 0; i < gm->gm_pf_num; i++) {
 		if (gm->gm_pfs[i].pseudoflavor == pseudoflavor) {
 			memcpy(info->oid.data, gm->gm_oid.data, gm->gm_oid.len);
 			info->oid.len = gm->gm_oid.len;
 			info->qop = gm->gm_pfs[i].qop;
 			info->service = gm->gm_pfs[i].service;
 			gss_mech_put(gm);
 			return 0;
 		}
 	}

 	gss_mech_put(gm);
 	return -ENOENT;
 }

 u32
 gss_pseudoflavor_to_service(struct gss_api_mech *gm, u32 pseudoflavor)
 {
 	int i;

 	for (i = 0; i < gm->gm_pf_num; i++) {
 		if (gm->gm_pfs[i].pseudoflavor == pseudoflavor)
 			return gm->gm_pfs[i].service;
 	}
 	return 0;
 }
 EXPORT_SYMBOL(gss_pseudoflavor_to_service);

 bool
 gss_pseudoflavor_to_datatouch(struct gss_api_mech *gm, u32 pseudoflavor)
 {
 	int i;

 	for (i = 0; i < gm->gm_pf_num; i++) {
 		if (gm->gm_pfs[i].pseudoflavor == pseudoflavor)
 			return gm->gm_pfs[i].datatouch;
 	}
 	return false;
 }

 char *
 gss_service_to_auth_domain_name(struct gss_api_mech *gm, u32 service)
 {
 	int i;

 	for (i = 0; i < gm->gm_pf_num; i++) {
 		if (gm->gm_pfs[i].service == service)
 			return gm->gm_pfs[i].auth_domain_name;
 	}
 	return NULL;
 }

 void
 gss_mech_put(struct gss_api_mech * gm)
 {
 	if (gm)
 		module_put(gm->gm_owner);
 }
 EXPORT_SYMBOL(gss_mech_put);

 /* The mech could probably be determined from the token instead, but it's just
  * as easy for now to pass it in. */
 int
 gss_import_sec_context(const void *input_token, size_t bufsize,
 		       struct gss_api_mech	*mech,
 		       struct gss_ctx		**ctx_id,
 		       time64_t			*endtime,
 		       gfp_t gfp_mask)
 {
 	if (!(*ctx_id = kzalloc(sizeof(**ctx_id), gfp_mask)))
 		return -ENOMEM;
 	(*ctx_id)->mech_type = gss_mech_get(mech);

 	return mech->gm_ops->gss_import_sec_context(input_token, bufsize,
 						*ctx_id, endtime, gfp_mask);
 }

 /* gss_get_mic: compute a mic over message and return mic_token. */

 u32
 gss_get_mic(struct gss_ctx	*context_handle,
 	    struct xdr_buf	*message,
 	    struct xdr_netobj	*mic_token)
 {
 	 return context_handle->mech_type->gm_ops
 		->gss_get_mic(context_handle,
 			      message,
 			      mic_token);
 }

 /* gss_verify_mic: check whether the provided mic_token verifies message. */

 u32
 gss_verify_mic(struct gss_ctx		*context_handle,
 	       struct xdr_buf		*message,
 	       struct xdr_netobj	*mic_token)
 {
 	return context_handle->mech_type->gm_ops
 		->gss_verify_mic(context_handle,
 				 message,
 				 mic_token);
 }

 /*
  * This function is called from both the client and server code.
  * Each makes guarantees about how much "slack" space is available
  * for the underlying function in "buf"'s head and tail while
  * performing the wrap.
  *
  * The client and server code allocate RPC_MAX_AUTH_SIZE extra
  * space in both the head and tail which is available for use by
  * the wrap function.
  *
  * Underlying functions should verify they do not use more than
  * RPC_MAX_AUTH_SIZE of extra space in either the head or tail
  * when performing the wrap.
  */
 u32
 gss_wrap(struct gss_ctx	*ctx_id,
 	 int		offset,
 	 struct xdr_buf	*buf,
 	 struct page	**inpages)
 {
 	return ctx_id->mech_type->gm_ops
 		->gss_wrap(ctx_id, offset, buf, inpages);
 }

 u32
 gss_unwrap(struct gss_ctx	*ctx_id,
 	   int			offset,
 	   int			len,
 	   struct xdr_buf	*buf)
 {
 	return ctx_id->mech_type->gm_ops
 		->gss_unwrap(ctx_id, offset, len, buf);
 }


 /* gss_delete_sec_context: free all resources associated with context_handle.
  * Note this differs from the RFC 2744-specified prototype in that we don't
  * bother returning an output token, since it would never be used anyway. */

 u32
 gss_delete_sec_context(struct gss_ctx	**context_handle)
 {
 	dprintk("RPC:       gss_delete_sec_context deleting %p\n",
 			*context_handle);

 	if (!*context_handle)
 		return GSS_S_NO_CONTEXT;
 	if ((*context_handle)->internal_ctx_id)
 		(*context_handle)->mech_type->gm_ops
 			->gss_delete_sec_context((*context_handle)
 							->internal_ctx_id);
 	gss_mech_put((*context_handle)->mech_type);
 	kfree(*context_handle);
 	*context_handle=NULL;
 	return GSS_S_COMPLETE;
 }
	// SPDX-License-Identifier: BSD-3-Clause
	/*
	* linux/net/sunrpc/gss_mech_switch.c
	*
	* Copyright (c) 2001 The Regents of the University of Michigan.
	* All rights reserved.
	*
	* J. Bruce Fields <bfields@umich.edu>
	*/

	#include <linux/types.h>
	#include <linux/slab.h>
	#include <linux/module.h>
	#include <linux/oid_registry.h>
	#include <linux/sunrpc/msg_prot.h>
	#include <linux/sunrpc/gss_asn1.h>
	#include <linux/sunrpc/auth_gss.h>
	#include <linux/sunrpc/svcauth_gss.h>
	#include <linux/sunrpc/gss_err.h>
	#include <linux/sunrpc/sched.h>
	#include <linux/sunrpc/gss_api.h>
	#include <linux/sunrpc/clnt.h>
	#include <trace/events/rpcgss.h>

	#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
	# define RPCDBG_FACILITY RPCDBG_AUTH
	#endif

	static LIST_HEAD(registered_mechs);
	static DEFINE_SPINLOCK(registered_mechs_lock);

	static void
	gss_mech_free(struct gss_api_mech *gm)
	{
	struct pf_desc *pf;
	int i;

	for (i = 0; i < gm->gm_pf_num; i++) {
	pf = &gm->gm_pfs[i];
	if (pf->domain)
	auth_domain_put(pf->domain);
	kfree(pf->auth_domain_name);
	pf->auth_domain_name = NULL;
	}
	}

	static inline char *
	make_auth_domain_name(char *name)
	{
	static char *prefix = "gss/";
	char *new;

	new = kmalloc(strlen(name) + strlen(prefix) + 1, GFP_KERNEL);
	if (new) {
	strcpy(new, prefix);
	strcat(new, name);
	}
	return new;
	}

	static int
	gss_mech_svc_setup(struct gss_api_mech *gm)
	{
	struct auth_domain *dom;
	struct pf_desc *pf;
	int i, status;

	for (i = 0; i < gm->gm_pf_num; i++) {
	pf = &gm->gm_pfs[i];
	pf->auth_domain_name = make_auth_domain_name(pf->name);
	status = -ENOMEM;
	if (pf->auth_domain_name == NULL)
	goto out;
	dom = svcauth_gss_register_pseudoflavor(
	pf->pseudoflavor, pf->auth_domain_name);
	if (IS_ERR(dom)) {
	status = PTR_ERR(dom);
	goto out;
	}
	pf->domain = dom;
	}
	return 0;
	out:
	gss_mech_free(gm);
	return status;
	}

	/**
	* gss_mech_register - register a GSS mechanism
	* @gm: GSS mechanism handle
	*
	* Returns zero if successful, or a negative errno.
	*/
	int gss_mech_register(struct gss_api_mech *gm)
	{
	int status;

	status = gss_mech_svc_setup(gm);
	if (status)
	return status;
	spin_lock(&registered_mechs_lock);
	list_add_rcu(&gm->gm_list, &registered_mechs);
	spin_unlock(&registered_mechs_lock);
	dprintk("RPC: registered gss mechanism %s\n", gm->gm_name);
	return 0;
	}
	EXPORT_SYMBOL_GPL(gss_mech_register);

	/**
	* gss_mech_unregister - release a GSS mechanism
	* @gm: GSS mechanism handle
	*
	*/
	void gss_mech_unregister(struct gss_api_mech *gm)
	{
	spin_lock(&registered_mechs_lock);
	list_del_rcu(&gm->gm_list);
	spin_unlock(&registered_mechs_lock);
	dprintk("RPC: unregistered gss mechanism %s\n", gm->gm_name);
	gss_mech_free(gm);
	}
	EXPORT_SYMBOL_GPL(gss_mech_unregister);

	struct gss_api_mech gss_mech_get(struct gss_api_mech gm)
	{
	__module_get(gm->gm_owner);
	return gm;
	}
	EXPORT_SYMBOL(gss_mech_get);

	static struct gss_api_mech *
	_gss_mech_get_by_name(const char *name)
	{
	struct gss_api_mech pos, gm = NULL;

	rcu_read_lock();
	list_for_each_entry_rcu(pos, &registered_mechs, gm_list) {
	if (0 == strcmp(name, pos->gm_name)) {
	if (try_module_get(pos->gm_owner))
	gm = pos;
	break;
	}
	}
	rcu_read_unlock();
	return gm;

	}

	struct gss_api_mech * gss_mech_get_by_name(const char *name)
	{
	struct gss_api_mech *gm = NULL;

	gm = _gss_mech_get_by_name(name);
	if (!gm) {
	request_module("rpc-auth-gss-%s", name);
	gm = _gss_mech_get_by_name(name);
	}
	return gm;
	}

	struct gss_api_mech gss_mech_get_by_OID(struct rpcsec_gss_oid obj)
	{
	struct gss_api_mech pos, gm = NULL;
	char buf[32];

	if (sprint_oid(obj->data, obj->len, buf, sizeof(buf)) < 0)
	return NULL;
	request_module("rpc-auth-gss-%s", buf);

	rcu_read_lock();
	list_for_each_entry_rcu(pos, &registered_mechs, gm_list) {
	if (obj->len == pos->gm_oid.len) {
	if (0 == memcmp(obj->data, pos->gm_oid.data, obj->len)) {
	if (try_module_get(pos->gm_owner))
	gm = pos;
	break;
	}
	}
	}
	rcu_read_unlock();
	if (!gm)
	trace_rpcgss_oid_to_mech(buf);
	return gm;
	}

	static inline int
	mech_supports_pseudoflavor(struct gss_api_mech *gm, u32 pseudoflavor)
	{
	int i;

	for (i = 0; i < gm->gm_pf_num; i++) {
	if (gm->gm_pfs[i].pseudoflavor == pseudoflavor)
	return 1;
	}
	return 0;
	}

	static struct gss_api_mech *_gss_mech_get_by_pseudoflavor(u32 pseudoflavor)
	{
	struct gss_api_mech gm = NULL, pos;

	rcu_read_lock();
	list_for_each_entry_rcu(pos, &registered_mechs, gm_list) {
	if (!mech_supports_pseudoflavor(pos, pseudoflavor))
	continue;
	if (try_module_get(pos->gm_owner))
	gm = pos;
	break;
	}
	rcu_read_unlock();
	return gm;
	}

	struct gss_api_mech *
	gss_mech_get_by_pseudoflavor(u32 pseudoflavor)
	{
	struct gss_api_mech *gm;

	gm = _gss_mech_get_by_pseudoflavor(pseudoflavor);

	if (!gm) {
	request_module("rpc-auth-gss-%u", pseudoflavor);
	gm = _gss_mech_get_by_pseudoflavor(pseudoflavor);
	}
	return gm;
	}

	/**
	* gss_svc_to_pseudoflavor - map a GSS service number to a pseudoflavor
	* @gm: GSS mechanism handle
	* @qop: GSS quality-of-protection value
	* @service: GSS service value
	*
	* Returns a matching security flavor, or RPC_AUTH_MAXFLAVOR if none is found.
	*/
	rpc_authflavor_t gss_svc_to_pseudoflavor(struct gss_api_mech *gm, u32 qop,
	u32 service)
	{
	int i;

	for (i = 0; i < gm->gm_pf_num; i++) {
	if (gm->gm_pfs[i].qop == qop &&
	gm->gm_pfs[i].service == service) {
	return gm->gm_pfs[i].pseudoflavor;
	}
	}
	return RPC_AUTH_MAXFLAVOR;
	}

	/**
	* gss_mech_info2flavor - look up a pseudoflavor given a GSS tuple
	* @info: a GSS mech OID, quality of protection, and service value
	*
	* Returns a matching pseudoflavor, or RPC_AUTH_MAXFLAVOR if the tuple is
	* not supported.
	*/
	rpc_authflavor_t gss_mech_info2flavor(struct rpcsec_gss_info *info)
	{
	rpc_authflavor_t pseudoflavor;
	struct gss_api_mech *gm;

	gm = gss_mech_get_by_OID(&info->oid);
	if (gm == NULL)
	return RPC_AUTH_MAXFLAVOR;

	pseudoflavor = gss_svc_to_pseudoflavor(gm, info->qop, info->service);

	gss_mech_put(gm);
	return pseudoflavor;
	}

	/**
	* gss_mech_flavor2info - look up a GSS tuple for a given pseudoflavor
	* @pseudoflavor: GSS pseudoflavor to match
	* @info: rpcsec_gss_info structure to fill in
	*
	* Returns zero and fills in "info" if pseudoflavor matches a
	* supported mechanism. Otherwise a negative errno is returned.
	*/
	int gss_mech_flavor2info(rpc_authflavor_t pseudoflavor,
	struct rpcsec_gss_info *info)
	{
	struct gss_api_mech *gm;
	int i;

	gm = gss_mech_get_by_pseudoflavor(pseudoflavor);
	if (gm == NULL)
	return -ENOENT;

	for (i = 0; i < gm->gm_pf_num; i++) {
	if (gm->gm_pfs[i].pseudoflavor == pseudoflavor) {
	memcpy(info->oid.data, gm->gm_oid.data, gm->gm_oid.len);
	info->oid.len = gm->gm_oid.len;
	info->qop = gm->gm_pfs[i].qop;
	info->service = gm->gm_pfs[i].service;
	gss_mech_put(gm);
	return 0;
	}
	}

	gss_mech_put(gm);
	return -ENOENT;
	}

	u32
	gss_pseudoflavor_to_service(struct gss_api_mech *gm, u32 pseudoflavor)
	{
	int i;

	for (i = 0; i < gm->gm_pf_num; i++) {
	if (gm->gm_pfs[i].pseudoflavor == pseudoflavor)
	return gm->gm_pfs[i].service;
	}
	return 0;
	}
	EXPORT_SYMBOL(gss_pseudoflavor_to_service);

	bool
	gss_pseudoflavor_to_datatouch(struct gss_api_mech *gm, u32 pseudoflavor)
	{
	int i;

	for (i = 0; i < gm->gm_pf_num; i++) {
	if (gm->gm_pfs[i].pseudoflavor == pseudoflavor)
	return gm->gm_pfs[i].datatouch;
	}
	return false;
	}

	char *
	gss_service_to_auth_domain_name(struct gss_api_mech *gm, u32 service)
	{
	int i;

	for (i = 0; i < gm->gm_pf_num; i++) {
	if (gm->gm_pfs[i].service == service)
	return gm->gm_pfs[i].auth_domain_name;
	}
	return NULL;
	}

	void
	gss_mech_put(struct gss_api_mech * gm)
	{
	if (gm)
	module_put(gm->gm_owner);
	}
	EXPORT_SYMBOL(gss_mech_put);

	/* The mech could probably be determined from the token instead, but it's just
	* as easy for now to pass it in. */
	int
	gss_import_sec_context(const void *input_token, size_t bufsize,
	struct gss_api_mech *mech,
	struct gss_ctx **ctx_id,
	time64_t *endtime,
	gfp_t gfp_mask)
	{
	if (!(ctx_id = kzalloc(sizeof(*ctx_id), gfp_mask)))
	return -ENOMEM;
	(*ctx_id)->mech_type = gss_mech_get(mech);

	return mech->gm_ops->gss_import_sec_context(input_token, bufsize,
	*ctx_id, endtime, gfp_mask);
	}

	/* gss_get_mic: compute a mic over message and return mic_token. */

	u32
	gss_get_mic(struct gss_ctx *context_handle,
	struct xdr_buf *message,
	struct xdr_netobj *mic_token)
	{
	return context_handle->mech_type->gm_ops
	->gss_get_mic(context_handle,
	message,
	mic_token);
	}

	/* gss_verify_mic: check whether the provided mic_token verifies message. */

	u32
	gss_verify_mic(struct gss_ctx *context_handle,
	struct xdr_buf *message,
	struct xdr_netobj *mic_token)
	{
	return context_handle->mech_type->gm_ops
	->gss_verify_mic(context_handle,
	message,
	mic_token);
	}

	/*
	* This function is called from both the client and server code.
	* Each makes guarantees about how much "slack" space is available
	* for the underlying function in "buf"'s head and tail while
	* performing the wrap.
	*
	* The client and server code allocate RPC_MAX_AUTH_SIZE extra
	* space in both the head and tail which is available for use by
	* the wrap function.
	*
	* Underlying functions should verify they do not use more than
	* RPC_MAX_AUTH_SIZE of extra space in either the head or tail
	* when performing the wrap.
	*/
	u32
	gss_wrap(struct gss_ctx *ctx_id,
	int offset,
	struct xdr_buf *buf,
	struct page **inpages)
	{
	return ctx_id->mech_type->gm_ops
	->gss_wrap(ctx_id, offset, buf, inpages);
	}

	u32
	gss_unwrap(struct gss_ctx *ctx_id,
	int offset,
	int len,
	struct xdr_buf *buf)
	{
	return ctx_id->mech_type->gm_ops
	->gss_unwrap(ctx_id, offset, len, buf);
	}


	/* gss_delete_sec_context: free all resources associated with context_handle.
	* Note this differs from the RFC 2744-specified prototype in that we don't
	* bother returning an output token, since it would never be used anyway. */

	u32
	gss_delete_sec_context(struct gss_ctx **context_handle)
	{
	dprintk("RPC: gss_delete_sec_context deleting %p\n",
	*context_handle);

	if (!*context_handle)
	return GSS_S_NO_CONTEXT;
	if ((*context_handle)->internal_ctx_id)
	(*context_handle)->mech_type->gm_ops
	->gss_delete_sec_context((*context_handle)
	->internal_ctx_id);
	gss_mech_put((*context_handle)->mech_type);
	kfree(*context_handle);
	*context_handle=NULL;
	return GSS_S_COMPLETE;
	}