// SPDX-License-Identifier: BSD-3-Clause
/*
 * linux/net/sunrpc/auth_gss/auth_gss.c
 *
 * RPCSEC_GSS client authentication.
 *
 *  Copyright (c) 2000 The Regents of the University of Michigan.
 *  All rights reserved.
 *
 *  Dug Song       <dugsong@monkey.org>
 *  Andy Adamson   <andros@umich.edu>
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/pagemap.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/auth.h>
#include <linux/sunrpc/auth_gss.h>
#include <linux/sunrpc/gss_krb5.h>
#include <linux/sunrpc/svcauth_gss.h>
#include <linux/sunrpc/gss_err.h>
#include <linux/workqueue.h>
#include <linux/sunrpc/rpc_pipe_fs.h>
#include <linux/sunrpc/gss_api.h>
#include <linux/uaccess.h>
#include <linux/hashtable.h>

#include "auth_gss_internal.h"
#include "../netns.h"

#include <trace/events/rpcgss.h>

static const struct rpc_authops authgss_ops;

static const struct rpc_credops gss_credops;
static const struct rpc_credops gss_nullops;

static void gss_free_callback(struct kref *kref);

#define GSS_RETRY_EXPIRED 5
static unsigned int gss_expired_cred_retry_delay = GSS_RETRY_EXPIRED;

#define GSS_KEY_EXPIRE_TIMEO 240
static unsigned int gss_key_expire_timeo = GSS_KEY_EXPIRE_TIMEO;

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

/*
 * This compile-time check verifies that we will not exceed the
 * slack space allotted by the client and server auth_gss code
 * before they call gss_wrap().
 */
#define GSS_KRB5_MAX_SLACK_NEEDED					\
	(GSS_KRB5_TOK_HDR_LEN		/* gss token header */		\
	+ GSS_KRB5_MAX_CKSUM_LEN	/* gss token checksum */	\
	+ GSS_KRB5_MAX_BLOCKSIZE	/* confounder */		\
	+ GSS_KRB5_MAX_BLOCKSIZE	/* possible padding */		\
	+ GSS_KRB5_TOK_HDR_LEN		/* encrypted hdr in v2 token */	\
	+ GSS_KRB5_MAX_CKSUM_LEN	/* encryption hmac */		\
	+ XDR_UNIT * 2			/* RPC verifier */		\
	+ GSS_KRB5_TOK_HDR_LEN						\
	+ GSS_KRB5_MAX_CKSUM_LEN)

#define GSS_CRED_SLACK		(RPC_MAX_AUTH_SIZE * 2)
/* length of a krb5 verifier (48), plus data added before arguments when
 * using integrity (two 4-byte integers): */
#define GSS_VERF_SLACK		100

static DEFINE_HASHTABLE(gss_auth_hash_table, 4);
static DEFINE_SPINLOCK(gss_auth_hash_lock);

struct gss_pipe {
	struct rpc_pipe_dir_object pdo;
	struct rpc_pipe *pipe;
	struct rpc_clnt *clnt;
	const char *name;
	struct kref kref;
};

struct gss_auth {
	struct kref kref;
	struct hlist_node hash;
	struct rpc_auth rpc_auth;
	struct gss_api_mech *mech;
	enum rpc_gss_svc service;
	struct rpc_clnt *client;
	struct net	*net;
	netns_tracker	ns_tracker;
	/*
	 * There are two upcall pipes; dentry[1], named "gssd", is used
	 * for the new text-based upcall; dentry[0] is named after the
	 * mechanism (for example, "krb5") and exists for
	 * backwards-compatibility with older gssd's.
	 */
	struct gss_pipe *gss_pipe[2];
	const char *target_name;
};

/* pipe_version >= 0 if and only if someone has a pipe open. */
static DEFINE_SPINLOCK(pipe_version_lock);
static struct rpc_wait_queue pipe_version_rpc_waitqueue;
static DECLARE_WAIT_QUEUE_HEAD(pipe_version_waitqueue);
static void gss_put_auth(struct gss_auth *gss_auth);

static void gss_free_ctx(struct gss_cl_ctx *);
static const struct rpc_pipe_ops gss_upcall_ops_v0;
static const struct rpc_pipe_ops gss_upcall_ops_v1;

static inline struct gss_cl_ctx *
gss_get_ctx(struct gss_cl_ctx *ctx)
{
	refcount_inc(&ctx->count);
	return ctx;
}

static inline void
gss_put_ctx(struct gss_cl_ctx *ctx)
{
	if (refcount_dec_and_test(&ctx->count))
		gss_free_ctx(ctx);
}

/* gss_cred_set_ctx:
 * called by gss_upcall_callback and gss_create_upcall in order
 * to set the gss context. The actual exchange of an old context
 * and a new one is protected by the pipe->lock.
 */
static void
gss_cred_set_ctx(struct rpc_cred *cred, struct gss_cl_ctx *ctx)
{
	struct gss_cred *gss_cred = container_of(cred, struct gss_cred, gc_base);

	if (!test_bit(RPCAUTH_CRED_NEW, &cred->cr_flags))
		return;
	gss_get_ctx(ctx);
	rcu_assign_pointer(gss_cred->gc_ctx, ctx);
	set_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
	smp_mb__before_atomic();
	clear_bit(RPCAUTH_CRED_NEW, &cred->cr_flags);
}

static struct gss_cl_ctx *
gss_cred_get_ctx(struct rpc_cred *cred)
{
	struct gss_cred *gss_cred = container_of(cred, struct gss_cred, gc_base);
	struct gss_cl_ctx *ctx = NULL;

	rcu_read_lock();
	ctx = rcu_dereference(gss_cred->gc_ctx);
	if (ctx)
		gss_get_ctx(ctx);
	rcu_read_unlock();
	return ctx;
}

static struct gss_cl_ctx *
gss_alloc_context(void)
{
	struct gss_cl_ctx *ctx;

	ctx = kzalloc_obj(*ctx);
	if (ctx != NULL) {
		ctx->gc_proc = RPC_GSS_PROC_DATA;
		ctx->gc_seq = 1;	/* NetApp 6.4R1 doesn't accept seq. no. 0 */
		spin_lock_init(&ctx->gc_seq_lock);
		refcount_set(&ctx->count,1);
	}
	return ctx;
}

#define GSSD_MIN_TIMEOUT (60 * 60)
static const void *
gss_fill_context(const void *p, const void *end, struct gss_cl_ctx *ctx, struct gss_api_mech *gm)
{
	const void *q;
	unsigned int seclen;
	unsigned int timeout;
	unsigned long now = jiffies;
	u32 window_size;
	int ret;

	/* First unsigned int gives the remaining lifetime in seconds of the
	 * credential - e.g. the remaining TGT lifetime for Kerberos or
	 * the -t value passed to GSSD.
	 */
	p = simple_get_bytes(p, end, &timeout, sizeof(timeout));
	if (IS_ERR(p))
		goto err;
	if (timeout == 0)
		timeout = GSSD_MIN_TIMEOUT;
	ctx->gc_expiry = now + ((unsigned long)timeout * HZ);
	/* Sequence number window. Determines the maximum number of
	 * simultaneous requests
	 */
	p = simple_get_bytes(p, end, &window_size, sizeof(window_size));
	if (IS_ERR(p))
		goto err;
	ctx->gc_win = window_size;
	/* gssd signals an error by passing ctx->gc_win = 0: */
	if (ctx->gc_win == 0) {
		/*
		 * in which case, p points to an error code. Anything other
		 * than -EKEYEXPIRED gets converted to -EACCES.
		 */
		p = simple_get_bytes(p, end, &ret, sizeof(ret));
		if (!IS_ERR(p))
			p = (ret == -EKEYEXPIRED) ? ERR_PTR(-EKEYEXPIRED) :
						    ERR_PTR(-EACCES);
		goto err;
	}
	/* copy the opaque wire context */
	p = simple_get_netobj(p, end, &ctx->gc_wire_ctx);
	if (IS_ERR(p))
		goto err;
	/* import the opaque security context */
	p  = simple_get_bytes(p, end, &seclen, sizeof(seclen));
	if (IS_ERR(p))
		goto err;
	q = (const void *)((const char *)p + seclen);
	if (unlikely(q > end || q < p)) {
		p = ERR_PTR(-EFAULT);
		goto err;
	}
	ret = gss_import_sec_context(p, seclen, gm, &ctx->gc_gss_ctx, NULL, GFP_KERNEL);
	if (ret < 0) {
		trace_rpcgss_import_ctx(ret);
		p = ERR_PTR(ret);
		goto err;
	}

	/* is there any trailing data? */
	if (q == end) {
		p = q;
		goto done;
	}

	/* pull in acceptor name (if there is one) */
	p = simple_get_netobj(q, end, &ctx->gc_acceptor);
	if (IS_ERR(p))
		goto err;
done:
	trace_rpcgss_context(window_size, ctx->gc_expiry, now, timeout,
			     ctx->gc_acceptor.len, ctx->gc_acceptor.data);
err:
	return p;
}

/* XXX: Need some documentation about why UPCALL_BUF_LEN is so small.
 *	Is user space expecting no more than UPCALL_BUF_LEN bytes?
 *	Note that there are now _two_ NI_MAXHOST sized data items
 *	being passed in this string.
 */
#define UPCALL_BUF_LEN	256

struct gss_upcall_msg {
	refcount_t count;
	kuid_t	uid;
	const char *service_name;
	struct rpc_pipe_msg msg;
	struct list_head list;
	struct gss_auth *auth;
	struct rpc_pipe *pipe;
	struct rpc_wait_queue rpc_waitqueue;
	wait_queue_head_t waitqueue;
	struct gss_cl_ctx *ctx;
	char databuf[UPCALL_BUF_LEN];
};

static int get_pipe_version(struct net *net)
{
	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
	int ret;

	spin_lock(&pipe_version_lock);
	if (sn->pipe_version >= 0) {
		atomic_inc(&sn->pipe_users);
		ret = sn->pipe_version;
	} else
		ret = -EAGAIN;
	spin_unlock(&pipe_version_lock);
	return ret;
}

static void put_pipe_version(struct net *net)
{
	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);

	if (atomic_dec_and_lock(&sn->pipe_users, &pipe_version_lock)) {
		sn->pipe_version = -1;
		spin_unlock(&pipe_version_lock);
	}
}

static void
gss_release_msg(struct gss_upcall_msg *gss_msg)
{
	struct net *net = gss_msg->auth->net;
	if (!refcount_dec_and_test(&gss_msg->count))
		return;
	put_pipe_version(net);
	BUG_ON(!list_empty(&gss_msg->list));
	if (gss_msg->ctx != NULL)
		gss_put_ctx(gss_msg->ctx);
	rpc_destroy_wait_queue(&gss_msg->rpc_waitqueue);
	gss_put_auth(gss_msg->auth);
	kfree_const(gss_msg->service_name);
	kfree(gss_msg);
}

static struct gss_upcall_msg *
__gss_find_upcall(struct rpc_pipe *pipe, kuid_t uid, const struct gss_auth *auth)
{
	struct gss_upcall_msg *pos;
	list_for_each_entry(pos, &pipe->in_downcall, list) {
		if (!uid_eq(pos->uid, uid))
			continue;
		if (pos->auth->service != auth->service)
			continue;
		refcount_inc(&pos->count);
		return pos;
	}
	return NULL;
}

/* Try to add an upcall to the pipefs queue.
 * If an upcall owned by our uid already exists, then we return a reference
 * to that upcall instead of adding the new upcall.
 */
static inline struct gss_upcall_msg *
gss_add_msg(struct gss_upcall_msg *gss_msg)
{
	struct rpc_pipe *pipe = gss_msg->pipe;
	struct gss_upcall_msg *old;

	spin_lock(&pipe->lock);
	old = __gss_find_upcall(pipe, gss_msg->uid, gss_msg->auth);
	if (old == NULL) {
		refcount_inc(&gss_msg->count);
		list_add(&gss_msg->list, &pipe->in_downcall);
	} else
		gss_msg = old;
	spin_unlock(&pipe->lock);
	return gss_msg;
}

static void
__gss_unhash_msg(struct gss_upcall_msg *gss_msg)
{
	list_del_init(&gss_msg->list);
	rpc_wake_up_status(&gss_msg->rpc_waitqueue, gss_msg->msg.errno);
	wake_up_all(&gss_msg->waitqueue);
	refcount_dec(&gss_msg->count);
}

static void
gss_unhash_msg(struct gss_upcall_msg *gss_msg)
{
	struct rpc_pipe *pipe = gss_msg->pipe;

	if (list_empty(&gss_msg->list))
		return;
	spin_lock(&pipe->lock);
	if (!list_empty(&gss_msg->list))
		__gss_unhash_msg(gss_msg);
	spin_unlock(&pipe->lock);
}

static void
gss_handle_downcall_result(struct gss_cred *gss_cred, struct gss_upcall_msg *gss_msg)
{
	switch (gss_msg->msg.errno) {
	case 0:
		if (gss_msg->ctx == NULL)
			break;
		clear_bit(RPCAUTH_CRED_NEGATIVE, &gss_cred->gc_base.cr_flags);
		gss_cred_set_ctx(&gss_cred->gc_base, gss_msg->ctx);
		break;
	case -EKEYEXPIRED:
		set_bit(RPCAUTH_CRED_NEGATIVE, &gss_cred->gc_base.cr_flags);
	}
	gss_cred->gc_upcall_timestamp = jiffies;
	gss_cred->gc_upcall = NULL;
	rpc_wake_up_status(&gss_msg->rpc_waitqueue, gss_msg->msg.errno);
}

static void
gss_upcall_callback(struct rpc_task *task)
{
	struct gss_cred *gss_cred = container_of(task->tk_rqstp->rq_cred,
			struct gss_cred, gc_base);
	struct gss_upcall_msg *gss_msg = gss_cred->gc_upcall;
	struct rpc_pipe *pipe = gss_msg->pipe;

	spin_lock(&pipe->lock);
	gss_handle_downcall_result(gss_cred, gss_msg);
	spin_unlock(&pipe->lock);
	task->tk_status = gss_msg->msg.errno;
	gss_release_msg(gss_msg);
}

static void gss_encode_v0_msg(struct gss_upcall_msg *gss_msg,
			      const struct cred *cred)
{
	struct user_namespace *userns = cred->user_ns;

	uid_t uid = from_kuid_munged(userns, gss_msg->uid);
	memcpy(gss_msg->databuf, &uid, sizeof(uid));
	gss_msg->msg.data = gss_msg->databuf;
	gss_msg->msg.len = sizeof(uid);

	BUILD_BUG_ON(sizeof(uid) > sizeof(gss_msg->databuf));
}

static ssize_t
gss_v0_upcall(struct file *file, struct rpc_pipe_msg *msg,
		char __user *buf, size_t buflen)
{
	struct gss_upcall_msg *gss_msg = container_of(msg,
						      struct gss_upcall_msg,
						      msg);
	if (msg->copied == 0)
		gss_encode_v0_msg(gss_msg, file->f_cred);
	return rpc_pipe_generic_upcall(file, msg, buf, buflen);
}

static int gss_encode_v1_msg(struct gss_upcall_msg *gss_msg,
				const char *service_name,
				const char *target_name,
				const struct cred *cred)
{
	struct user_namespace *userns = cred->user_ns;
	struct gss_api_mech *mech = gss_msg->auth->mech;
	char *p = gss_msg->databuf;
	size_t buflen = sizeof(gss_msg->databuf);
	int len;

	len = scnprintf(p, buflen, "mech=%s uid=%d", mech->gm_name,
			from_kuid_munged(userns, gss_msg->uid));
	buflen -= len;
	p += len;
	gss_msg->msg.len = len;

	/*
	 * target= is a full service principal that names the remote
	 * identity that we are authenticating to.
	 */
	if (target_name) {
		len = scnprintf(p, buflen, " target=%s", target_name);
		buflen -= len;
		p += len;
		gss_msg->msg.len += len;
	}

	/*
	 * gssd uses service= and srchost= to select a matching key from
	 * the system's keytab to use as the source principal.
	 *
	 * service= is the service name part of the source principal,
	 * or "*" (meaning choose any).
	 *
	 * srchost= is the hostname part of the source principal. When
	 * not provided, gssd uses the local hostname.
	 */
	if (service_name) {
		char *c = strchr(service_name, '@');

		if (!c)
			len = scnprintf(p, buflen, " service=%s",
					service_name);
		else
			len = scnprintf(p, buflen,
					" service=%.*s srchost=%s",
					(int)(c - service_name),
					service_name, c + 1);
		buflen -= len;
		p += len;
		gss_msg->msg.len += len;
	}

	if (mech->gm_upcall_enctypes) {
		len = scnprintf(p, buflen, " enctypes=%s",
				mech->gm_upcall_enctypes);
		buflen -= len;
		p += len;
		gss_msg->msg.len += len;
	}
	trace_rpcgss_upcall_msg(gss_msg->databuf);
	len = scnprintf(p, buflen, "\n");
	if (len == 0)
		goto out_overflow;
	gss_msg->msg.len += len;
	gss_msg->msg.data = gss_msg->databuf;
	return 0;
out_overflow:
	WARN_ON_ONCE(1);
	return -ENOMEM;
}

static ssize_t
gss_v1_upcall(struct file *file, struct rpc_pipe_msg *msg,
		char __user *buf, size_t buflen)
{
	struct gss_upcall_msg *gss_msg = container_of(msg,
						      struct gss_upcall_msg,
						      msg);
	int err;
	if (msg->copied == 0) {
		err = gss_encode_v1_msg(gss_msg,
					gss_msg->service_name,
					gss_msg->auth->target_name,
					file->f_cred);
		if (err)
			return err;
	}
	return rpc_pipe_generic_upcall(file, msg, buf, buflen);
}

static struct gss_upcall_msg *
gss_alloc_msg(struct gss_auth *gss_auth,
		kuid_t uid, const char *service_name)
{
	struct gss_upcall_msg *gss_msg;
	int vers;
	int err = -ENOMEM;

	gss_msg = kzalloc_obj(*gss_msg);
	if (gss_msg == NULL)
		goto err;
	vers = get_pipe_version(gss_auth->net);
	err = vers;
	if (err < 0)
		goto err_free_msg;
	gss_msg->pipe = gss_auth->gss_pipe[vers]->pipe;
	INIT_LIST_HEAD(&gss_msg->list);
	rpc_init_wait_queue(&gss_msg->rpc_waitqueue, "RPCSEC_GSS upcall waitq");
	init_waitqueue_head(&gss_msg->waitqueue);
	refcount_set(&gss_msg->count, 1);
	gss_msg->uid = uid;
	gss_msg->auth = gss_auth;
	kref_get(&gss_auth->kref);
	if (service_name) {
		gss_msg->service_name = kstrdup_const(service_name, GFP_KERNEL);
		if (!gss_msg->service_name) {
			err = -ENOMEM;
			goto err_put_pipe_version;
		}
	}
	return gss_msg;
err_put_pipe_version:
	kref_put(&gss_auth->kref, gss_free_callback);
	put_pipe_version(gss_auth->net);
err_free_msg:
	kfree(gss_msg);
err:
	return ERR_PTR(err);
}

static struct gss_upcall_msg *
gss_setup_upcall(struct gss_auth *gss_auth, struct rpc_cred *cred)
{
	struct gss_cred *gss_cred = container_of(cred,
			struct gss_cred, gc_base);
	struct gss_upcall_msg *gss_new, *gss_msg;
	kuid_t uid = cred->cr_cred->fsuid;

	gss_new = gss_alloc_msg(gss_auth, uid, gss_cred->gc_principal);
	if (IS_ERR(gss_new))
		return gss_new;
	gss_msg = gss_add_msg(gss_new);
	if (gss_msg == gss_new) {
		int res;
		refcount_inc(&gss_msg->count);
		res = rpc_queue_upcall(gss_new->pipe, &gss_new->msg);
		if (res) {
			gss_unhash_msg(gss_new);
			refcount_dec(&gss_msg->count);
			gss_release_msg(gss_new);
			gss_msg = ERR_PTR(res);
		}
	} else
		gss_release_msg(gss_new);
	return gss_msg;
}

static void warn_gssd(void)
{
	dprintk("AUTH_GSS upcall failed. Please check user daemon is running.\n");
}

static inline int
gss_refresh_upcall(struct rpc_task *task)
{
	struct rpc_cred *cred = task->tk_rqstp->rq_cred;
	struct gss_auth *gss_auth = container_of(cred->cr_auth,
			struct gss_auth, rpc_auth);
	struct gss_cred *gss_cred = container_of(cred,
			struct gss_cred, gc_base);
	struct gss_upcall_msg *gss_msg;
	struct rpc_pipe *pipe;
	int err = 0;

	gss_msg = gss_setup_upcall(gss_auth, cred);
	if (PTR_ERR(gss_msg) == -EAGAIN) {
		/* XXX: warning on the first, under the assumption we
		 * shouldn't normally hit this case on a refresh. */
		warn_gssd();
		rpc_sleep_on_timeout(&pipe_version_rpc_waitqueue,
				task, NULL, jiffies + (15 * HZ));
		err = -EAGAIN;
		goto out;
	}
	if (IS_ERR(gss_msg)) {
		err = PTR_ERR(gss_msg);
		goto out;
	}
	pipe = gss_msg->pipe;
	spin_lock(&pipe->lock);
	if (gss_cred->gc_upcall != NULL)
		rpc_sleep_on(&gss_cred->gc_upcall->rpc_waitqueue, task, NULL);
	else if (gss_msg->ctx == NULL && gss_msg->msg.errno >= 0) {
		gss_cred->gc_upcall = gss_msg;
		/* gss_upcall_callback will release the reference to gss_upcall_msg */
		refcount_inc(&gss_msg->count);
		rpc_sleep_on(&gss_msg->rpc_waitqueue, task, gss_upcall_callback);
	} else {
		gss_handle_downcall_result(gss_cred, gss_msg);
		err = gss_msg->msg.errno;
	}
	spin_unlock(&pipe->lock);
	gss_release_msg(gss_msg);
out:
	trace_rpcgss_upcall_result(from_kuid(&init_user_ns,
					     cred->cr_cred->fsuid), err);
	return err;
}

static inline int
gss_create_upcall(struct gss_auth *gss_auth, struct gss_cred *gss_cred)
{
	struct net *net = gss_auth->net;
	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
	struct rpc_pipe *pipe;
	struct rpc_cred *cred = &gss_cred->gc_base;
	struct gss_upcall_msg *gss_msg;
	DEFINE_WAIT(wait);
	int err;

retry:
	err = 0;
	/* if gssd is down, just skip upcalling altogether */
	if (!gssd_running(net)) {
		warn_gssd();
		err = -EACCES;
		goto out;
	}
	gss_msg = gss_setup_upcall(gss_auth, cred);
	if (PTR_ERR(gss_msg) == -EAGAIN) {
		err = wait_event_interruptible_timeout(pipe_version_waitqueue,
				sn->pipe_version >= 0, 15 * HZ);
		if (sn->pipe_version < 0) {
			warn_gssd();
			err = -EACCES;
		}
		if (err < 0)
			goto out;
		goto retry;
	}
	if (IS_ERR(gss_msg)) {
		err = PTR_ERR(gss_msg);
		goto out;
	}
	pipe = gss_msg->pipe;
	for (;;) {
		prepare_to_wait(&gss_msg->waitqueue, &wait, TASK_KILLABLE);
		spin_lock(&pipe->lock);
		if (gss_msg->ctx != NULL || gss_msg->msg.errno < 0) {
			break;
		}
		spin_unlock(&pipe->lock);
		if (fatal_signal_pending(current)) {
			err = -ERESTARTSYS;
			goto out_intr;
		}
		schedule();
	}
	if (gss_msg->ctx) {
		trace_rpcgss_ctx_init(gss_cred);
		gss_cred_set_ctx(cred, gss_msg->ctx);
	} else {
		err = gss_msg->msg.errno;
	}
	spin_unlock(&pipe->lock);
out_intr:
	finish_wait(&gss_msg->waitqueue, &wait);
	gss_release_msg(gss_msg);
out:
	trace_rpcgss_upcall_result(from_kuid(&init_user_ns,
					     cred->cr_cred->fsuid), err);
	return err;
}

static struct gss_upcall_msg *
gss_find_downcall(struct rpc_pipe *pipe, kuid_t uid)
{
	struct gss_upcall_msg *pos;
	list_for_each_entry(pos, &pipe->in_downcall, list) {
		if (!uid_eq(pos->uid, uid))
			continue;
		if (!rpc_msg_is_inflight(&pos->msg))
			continue;
		refcount_inc(&pos->count);
		return pos;
	}
	return NULL;
}

#define MSG_BUF_MAXSIZE 1024

static ssize_t
gss_pipe_downcall(struct file *filp, const char __user *src, size_t mlen)
{
	const void *p, *end;
	void *buf;
	struct gss_upcall_msg *gss_msg;
	struct rpc_pipe *pipe = RPC_I(file_inode(filp))->pipe;
	struct gss_cl_ctx *ctx;
	uid_t id;
	kuid_t uid;
	ssize_t err = -EFBIG;

	if (mlen > MSG_BUF_MAXSIZE)
		goto out;
	err = -ENOMEM;
	buf = kmalloc(mlen, GFP_KERNEL);
	if (!buf)
		goto out;

	err = -EFAULT;
	if (copy_from_user(buf, src, mlen))
		goto err;

	end = (const void *)((char *)buf + mlen);
	p = simple_get_bytes(buf, end, &id, sizeof(id));
	if (IS_ERR(p)) {
		err = PTR_ERR(p);
		goto err;
	}

	uid = make_kuid(current_user_ns(), id);
	if (!uid_valid(uid)) {
		err = -EINVAL;
		goto err;
	}

	err = -ENOMEM;
	ctx = gss_alloc_context();
	if (ctx == NULL)
		goto err;

	err = -ENOENT;
	/* Find a matching upcall */
	spin_lock(&pipe->lock);
	gss_msg = gss_find_downcall(pipe, uid);
	if (gss_msg == NULL) {
		spin_unlock(&pipe->lock);
		goto err_put_ctx;
	}
	list_del_init(&gss_msg->list);
	spin_unlock(&pipe->lock);

	p = gss_fill_context(p, end, ctx, gss_msg->auth->mech);
	if (IS_ERR(p)) {
		err = PTR_ERR(p);
		switch (err) {
		case -EACCES:
		case -EKEYEXPIRED:
			gss_msg->msg.errno = err;
			err = mlen;
			break;
		case -EFAULT:
		case -ENOMEM:
		case -EINVAL:
		case -ENOSYS:
			gss_msg->msg.errno = -EAGAIN;
			break;
		default:
			printk(KERN_CRIT "%s: bad return from "
				"gss_fill_context: %zd\n", __func__, err);
			gss_msg->msg.errno = -EIO;
		}
		goto err_release_msg;
	}
	gss_msg->ctx = gss_get_ctx(ctx);
	err = mlen;

err_release_msg:
	spin_lock(&pipe->lock);
	__gss_unhash_msg(gss_msg);
	spin_unlock(&pipe->lock);
	gss_release_msg(gss_msg);
err_put_ctx:
	gss_put_ctx(ctx);
err:
	kfree(buf);
out:
	return err;
}

static int gss_pipe_open(struct inode *inode, int new_version)
{
	struct net *net = inode->i_sb->s_fs_info;
	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
	int ret = 0;

	spin_lock(&pipe_version_lock);
	if (sn->pipe_version < 0) {
		/* First open of any gss pipe determines the version: */
		sn->pipe_version = new_version;
		rpc_wake_up(&pipe_version_rpc_waitqueue);
		wake_up(&pipe_version_waitqueue);
	} else if (sn->pipe_version != new_version) {
		/* Trying to open a pipe of a different version */
		ret = -EBUSY;
		goto out;
	}
	atomic_inc(&sn->pipe_users);
out:
	spin_unlock(&pipe_version_lock);
	return ret;

}

static int gss_pipe_open_v0(struct inode *inode)
{
	return gss_pipe_open(inode, 0);
}

static int gss_pipe_open_v1(struct inode *inode)
{
	return gss_pipe_open(inode, 1);
}

static void
gss_pipe_release(struct inode *inode)
{
	struct net *net = inode->i_sb->s_fs_info;
	struct rpc_pipe *pipe = RPC_I(inode)->pipe;
	struct gss_upcall_msg *gss_msg;

restart:
	spin_lock(&pipe->lock);
	list_for_each_entry(gss_msg, &pipe->in_downcall, list) {

		if (!list_empty(&gss_msg->msg.list))
			continue;
		gss_msg->msg.errno = -EPIPE;
		refcount_inc(&gss_msg->count);
		__gss_unhash_msg(gss_msg);
		spin_unlock(&pipe->lock);
		gss_release_msg(gss_msg);
		goto restart;
	}
	spin_unlock(&pipe->lock);

	put_pipe_version(net);
}

static void
gss_pipe_destroy_msg(struct rpc_pipe_msg *msg)
{
	struct gss_upcall_msg *gss_msg = container_of(msg, struct gss_upcall_msg, msg);

	if (msg->errno < 0) {
		refcount_inc(&gss_msg->count);
		gss_unhash_msg(gss_msg);
		if (msg->errno == -ETIMEDOUT)
			warn_gssd();
		gss_release_msg(gss_msg);
	}
	gss_release_msg(gss_msg);
}

static void gss_pipe_dentry_destroy(struct dentry *dir,
		struct rpc_pipe_dir_object *pdo)
{
	struct gss_pipe *gss_pipe = pdo->pdo_data;

	rpc_unlink(gss_pipe->pipe);
}

static int gss_pipe_dentry_create(struct dentry *dir,
		struct rpc_pipe_dir_object *pdo)
{
	struct gss_pipe *p = pdo->pdo_data;

	return rpc_mkpipe_dentry(dir, p->name, p->clnt, p->pipe);
}

static const struct rpc_pipe_dir_object_ops gss_pipe_dir_object_ops = {
	.create = gss_pipe_dentry_create,
	.destroy = gss_pipe_dentry_destroy,
};

static struct gss_pipe *gss_pipe_alloc(struct rpc_clnt *clnt,
		const char *name,
		const struct rpc_pipe_ops *upcall_ops)
{
	struct gss_pipe *p;
	int err = -ENOMEM;

	p = kmalloc_obj(*p);
	if (p == NULL)
		goto err;
	p->pipe = rpc_mkpipe_data(upcall_ops, RPC_PIPE_WAIT_FOR_OPEN);
	if (IS_ERR(p->pipe)) {
		err = PTR_ERR(p->pipe);
		goto err_free_gss_pipe;
	}
	p->name = name;
	p->clnt = clnt;
	kref_init(&p->kref);
	rpc_init_pipe_dir_object(&p->pdo,
			&gss_pipe_dir_object_ops,
			p);
	return p;
err_free_gss_pipe:
	kfree(p);
err:
	return ERR_PTR(err);
}

struct gss_alloc_pdo {
	struct rpc_clnt *clnt;
	const char *name;
	const struct rpc_pipe_ops *upcall_ops;
};

static int gss_pipe_match_pdo(struct rpc_pipe_dir_object *pdo, void *data)
{
	struct gss_pipe *gss_pipe;
	struct gss_alloc_pdo *args = data;

	if (pdo->pdo_ops != &gss_pipe_dir_object_ops)
		return 0;
	gss_pipe = container_of(pdo, struct gss_pipe, pdo);
	if (strcmp(gss_pipe->name, args->name) != 0)
		return 0;
	if (!kref_get_unless_zero(&gss_pipe->kref))
		return 0;
	return 1;
}

static struct rpc_pipe_dir_object *gss_pipe_alloc_pdo(void *data)
{
	struct gss_pipe *gss_pipe;
	struct gss_alloc_pdo *args = data;

	gss_pipe = gss_pipe_alloc(args->clnt, args->name, args->upcall_ops);
	if (!IS_ERR(gss_pipe))
		return &gss_pipe->pdo;
	return NULL;
}

static struct gss_pipe *gss_pipe_get(struct rpc_clnt *clnt,
		const char *name,
		const struct rpc_pipe_ops *upcall_ops)
{
	struct net *net = rpc_net_ns(clnt);
	struct rpc_pipe_dir_object *pdo;
	struct gss_alloc_pdo args = {
		.clnt = clnt,
		.name = name,
		.upcall_ops = upcall_ops,
	};

	pdo = rpc_find_or_alloc_pipe_dir_object(net,
			&clnt->cl_pipedir_objects,
			gss_pipe_match_pdo,
			gss_pipe_alloc_pdo,
			&args);
	if (pdo != NULL)
		return container_of(pdo, struct gss_pipe, pdo);
	return ERR_PTR(-ENOMEM);
}

static void __gss_pipe_free(struct gss_pipe *p)
{
	struct rpc_clnt *clnt = p->clnt;
	struct net *net = rpc_net_ns(clnt);

	rpc_remove_pipe_dir_object(net,
			&clnt->cl_pipedir_objects,
			&p->pdo);
	rpc_destroy_pipe_data(p->pipe);
	kfree(p);
}

static void __gss_pipe_release(struct kref *kref)
{
	struct gss_pipe *p = container_of(kref, struct gss_pipe, kref);

	__gss_pipe_free(p);
}

static void gss_pipe_free(struct gss_pipe *p)
{
	if (p != NULL)
		kref_put(&p->kref, __gss_pipe_release);
}

/*
 * NOTE: we have the opportunity to use different
 * parameters based on the input flavor (which must be a pseudoflavor)
 */
static struct gss_auth *
gss_create_new(const struct rpc_auth_create_args *args, struct rpc_clnt *clnt)
{
	rpc_authflavor_t flavor = args->pseudoflavor;
	struct gss_auth *gss_auth;
	struct gss_pipe *gss_pipe;
	struct rpc_auth * auth;
	int err = -ENOMEM; /* XXX? */

	if (!try_module_get(THIS_MODULE))
		return ERR_PTR(err);
	if (!(gss_auth = kmalloc_obj(*gss_auth)))
		goto out_dec;
	INIT_HLIST_NODE(&gss_auth->hash);
	gss_auth->target_name = NULL;
	if (args->target_name) {
		gss_auth->target_name = kstrdup(args->target_name, GFP_KERNEL);
		if (gss_auth->target_name == NULL)
			goto err_free;
	}
	gss_auth->client = clnt;
	gss_auth->net = get_net_track(rpc_net_ns(clnt), &gss_auth->ns_tracker,
				      GFP_KERNEL);
	err = -EINVAL;
	gss_auth->mech = gss_mech_get_by_pseudoflavor(flavor);
	if (!gss_auth->mech)
		goto err_put_net;
	gss_auth->service = gss_pseudoflavor_to_service(gss_auth->mech, flavor);
	if (gss_auth->service == 0)
		goto err_put_mech;
	if (!gssd_running(gss_auth->net))
		goto err_put_mech;
	auth = &gss_auth->rpc_auth;
	auth->au_cslack = GSS_CRED_SLACK >> 2;
	BUILD_BUG_ON(GSS_KRB5_MAX_SLACK_NEEDED > RPC_MAX_AUTH_SIZE);
	auth->au_rslack = GSS_KRB5_MAX_SLACK_NEEDED >> 2;
	auth->au_verfsize = GSS_VERF_SLACK >> 2;
	auth->au_ralign = GSS_VERF_SLACK >> 2;
	__set_bit(RPCAUTH_AUTH_UPDATE_SLACK, &auth->au_flags);
	auth->au_ops = &authgss_ops;
	auth->au_flavor = flavor;
	if (gss_pseudoflavor_to_datatouch(gss_auth->mech, flavor))
		__set_bit(RPCAUTH_AUTH_DATATOUCH, &auth->au_flags);
	refcount_set(&auth->au_count, 1);
	kref_init(&gss_auth->kref);

	err = rpcauth_init_credcache(auth);
	if (err)
		goto err_put_mech;
	/*
	 * Note: if we created the old pipe first, then someone who
	 * examined the directory at the right moment might conclude
	 * that we supported only the old pipe.  So we instead create
	 * the new pipe first.
	 */
	gss_pipe = gss_pipe_get(clnt, "gssd", &gss_upcall_ops_v1);
	if (IS_ERR(gss_pipe)) {
		err = PTR_ERR(gss_pipe);
		goto err_destroy_credcache;
	}
	gss_auth->gss_pipe[1] = gss_pipe;

	gss_pipe = gss_pipe_get(clnt, gss_auth->mech->gm_name,
			&gss_upcall_ops_v0);
	if (IS_ERR(gss_pipe)) {
		err = PTR_ERR(gss_pipe);
		goto err_destroy_pipe_1;
	}
	gss_auth->gss_pipe[0] = gss_pipe;

	return gss_auth;
err_destroy_pipe_1:
	gss_pipe_free(gss_auth->gss_pipe[1]);
err_destroy_credcache:
	rpcauth_destroy_credcache(auth);
err_put_mech:
	gss_mech_put(gss_auth->mech);
err_put_net:
	put_net_track(gss_auth->net, &gss_auth->ns_tracker);
err_free:
	kfree(gss_auth->target_name);
	kfree(gss_auth);
out_dec:
	module_put(THIS_MODULE);
	trace_rpcgss_createauth(flavor, err);
	return ERR_PTR(err);
}

static void
gss_free(struct gss_auth *gss_auth)
{
	gss_pipe_free(gss_auth->gss_pipe[0]);
	gss_pipe_free(gss_auth->gss_pipe[1]);
	gss_mech_put(gss_auth->mech);
	put_net_track(gss_auth->net, &gss_auth->ns_tracker);
	kfree(gss_auth->target_name);

	kfree(gss_auth);
	module_put(THIS_MODULE);
}

static void
gss_free_callback(struct kref *kref)
{
	struct gss_auth *gss_auth = container_of(kref, struct gss_auth, kref);

	gss_free(gss_auth);
}

static void
gss_put_auth(struct gss_auth *gss_auth)
{
	kref_put(&gss_auth->kref, gss_free_callback);
}

static void
gss_destroy(struct rpc_auth *auth)
{
	struct gss_auth *gss_auth = container_of(auth,
			struct gss_auth, rpc_auth);

	if (hash_hashed(&gss_auth->hash)) {
		spin_lock(&gss_auth_hash_lock);
		hash_del(&gss_auth->hash);
		spin_unlock(&gss_auth_hash_lock);
	}

	gss_pipe_free(gss_auth->gss_pipe[0]);
	gss_auth->gss_pipe[0] = NULL;
	gss_pipe_free(gss_auth->gss_pipe[1]);
	gss_auth->gss_pipe[1] = NULL;
	rpcauth_destroy_credcache(auth);

	gss_put_auth(gss_auth);
}

/*
 * Auths may be shared between rpc clients that were cloned from a
 * common client with the same xprt, if they also share the flavor and
 * target_name.
 *
 * The auth is looked up from the oldest parent sharing the same
 * cl_xprt, and the auth itself references only that common parent
 * (which is guaranteed to last as long as any of its descendants).
 */
static struct gss_auth *
gss_auth_find_or_add_hashed(const struct rpc_auth_create_args *args,
		struct rpc_clnt *clnt,
		struct gss_auth *new)
{
	struct gss_auth *gss_auth;
	unsigned long hashval = (unsigned long)clnt;

	spin_lock(&gss_auth_hash_lock);
	hash_for_each_possible(gss_auth_hash_table,
			gss_auth,
			hash,
			hashval) {
		if (gss_auth->client != clnt)
			continue;
		if (gss_auth->rpc_auth.au_flavor != args->pseudoflavor)
			continue;
		if (gss_auth->target_name != args->target_name) {
			if (gss_auth->target_name == NULL)
				continue;
			if (args->target_name == NULL)
				continue;
			if (strcmp(gss_auth->target_name, args->target_name))
				continue;
		}
		if (!refcount_inc_not_zero(&gss_auth->rpc_auth.au_count))
			continue;
		goto out;
	}
	if (new)
		hash_add(gss_auth_hash_table, &new->hash, hashval);
	gss_auth = new;
out:
	spin_unlock(&gss_auth_hash_lock);
	return gss_auth;
}

static struct gss_auth *
gss_create_hashed(const struct rpc_auth_create_args *args,
		  struct rpc_clnt *clnt)
{
	struct gss_auth *gss_auth;
	struct gss_auth *new;

	gss_auth = gss_auth_find_or_add_hashed(args, clnt, NULL);
	if (gss_auth != NULL)
		goto out;
	new = gss_create_new(args, clnt);
	if (IS_ERR(new))
		return new;
	gss_auth = gss_auth_find_or_add_hashed(args, clnt, new);
	if (gss_auth != new)
		gss_destroy(&new->rpc_auth);
out:
	return gss_auth;
}

static struct rpc_auth *
gss_create(const struct rpc_auth_create_args *args, struct rpc_clnt *clnt)
{
	struct gss_auth *gss_auth;
	struct rpc_xprt_switch *xps = rcu_access_pointer(clnt->cl_xpi.xpi_xpswitch);

	while (clnt != clnt->cl_parent) {
		struct rpc_clnt *parent = clnt->cl_parent;
		/* Find the original parent for this transport */
		if (rcu_access_pointer(parent->cl_xpi.xpi_xpswitch) != xps)
			break;
		clnt = parent;
	}

	gss_auth = gss_create_hashed(args, clnt);
	if (IS_ERR(gss_auth))
		return ERR_CAST(gss_auth);
	return &gss_auth->rpc_auth;
}

static struct gss_cred *
gss_dup_cred(struct gss_auth *gss_auth, struct gss_cred *gss_cred)
{
	struct gss_cred *new;

	/* Make a copy of the cred so that we can reference count it */
	new = kzalloc_obj(*gss_cred);
	if (new) {
		struct auth_cred acred = {
			.cred = gss_cred->gc_base.cr_cred,
		};
		struct gss_cl_ctx *ctx =
			rcu_dereference_protected(gss_cred->gc_ctx, 1);

		rpcauth_init_cred(&new->gc_base, &acred,
				&gss_auth->rpc_auth,
				&gss_nullops);
		new->gc_base.cr_flags = 1UL << RPCAUTH_CRED_UPTODATE;
		new->gc_service = gss_cred->gc_service;
		new->gc_principal = gss_cred->gc_principal;
		kref_get(&gss_auth->kref);
		rcu_assign_pointer(new->gc_ctx, ctx);
		gss_get_ctx(ctx);
	}
	return new;
}

/*
 * gss_send_destroy_context will cause the RPCSEC_GSS to send a NULL RPC call
 * to the server with the GSS control procedure field set to
 * RPC_GSS_PROC_DESTROY. This should normally cause the server to release
 * all RPCSEC_GSS state associated with that context.
 */
static void
gss_send_destroy_context(struct rpc_cred *cred)
{
	struct gss_cred *gss_cred = container_of(cred, struct gss_cred, gc_base);
	struct gss_auth *gss_auth = container_of(cred->cr_auth, struct gss_auth, rpc_auth);
	struct gss_cl_ctx *ctx = rcu_dereference_protected(gss_cred->gc_ctx, 1);
	struct gss_cred *new;
	struct rpc_task *task;

	new = gss_dup_cred(gss_auth, gss_cred);
	if (new) {
		ctx->gc_proc = RPC_GSS_PROC_DESTROY;

		trace_rpcgss_ctx_destroy(gss_cred);
		task = rpc_call_null(gss_auth->client, &new->gc_base,
				     RPC_TASK_ASYNC);
		if (!IS_ERR(task))
			rpc_put_task(task);

		put_rpccred(&new->gc_base);
	}
}

/* gss_destroy_cred (and gss_free_ctx) are used to clean up after failure
 * to create a new cred or context, so they check that things have been
 * allocated before freeing them. */
static void
gss_do_free_ctx(struct gss_cl_ctx *ctx)
{
	gss_delete_sec_context(&ctx->gc_gss_ctx);
	kfree(ctx->gc_wire_ctx.data);
	kfree(ctx->gc_acceptor.data);
	kfree(ctx);
}

static void
gss_free_ctx_callback(struct rcu_head *head)
{
	struct gss_cl_ctx *ctx = container_of(head, struct gss_cl_ctx, gc_rcu);
	gss_do_free_ctx(ctx);
}

static void
gss_free_ctx(struct gss_cl_ctx *ctx)
{
	call_rcu(&ctx->gc_rcu, gss_free_ctx_callback);
}

static void
gss_free_cred(struct gss_cred *gss_cred)
{
	kfree(gss_cred);
}

static void
gss_free_cred_callback(struct rcu_head *head)
{
	struct gss_cred *gss_cred = container_of(head, struct gss_cred, gc_base.cr_rcu);
	gss_free_cred(gss_cred);
}

static void
gss_destroy_nullcred(struct rpc_cred *cred)
{
	struct gss_cred *gss_cred = container_of(cred, struct gss_cred, gc_base);
	struct gss_auth *gss_auth = container_of(cred->cr_auth, struct gss_auth, rpc_auth);
	struct gss_cl_ctx *ctx = rcu_dereference_protected(gss_cred->gc_ctx, 1);

	RCU_INIT_POINTER(gss_cred->gc_ctx, NULL);
	put_cred(cred->cr_cred);
	call_rcu(&cred->cr_rcu, gss_free_cred_callback);
	if (ctx)
		gss_put_ctx(ctx);
	gss_put_auth(gss_auth);
}

static void
gss_destroy_cred(struct rpc_cred *cred)
{
	if (test_and_clear_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) != 0)
		gss_send_destroy_context(cred);
	gss_destroy_nullcred(cred);
}

static int
gss_hash_cred(struct auth_cred *acred, unsigned int hashbits)
{
	return hash_64(from_kuid(&init_user_ns, acred->cred->fsuid), hashbits);
}

/*
 * Lookup RPCSEC_GSS cred for the current process
 */
static struct rpc_cred *gss_lookup_cred(struct rpc_auth *auth,
					struct auth_cred *acred, int flags)
{
	return rpcauth_lookup_credcache(auth, acred, flags,
					rpc_task_gfp_mask());
}

static struct rpc_cred *
gss_create_cred(struct rpc_auth *auth, struct auth_cred *acred, int flags, gfp_t gfp)
{
	struct gss_auth *gss_auth = container_of(auth, struct gss_auth, rpc_auth);
	struct gss_cred	*cred = NULL;
	int err = -ENOMEM;

	if (!(cred = kzalloc_obj(*cred, gfp)))
		goto out_err;

	rpcauth_init_cred(&cred->gc_base, acred, auth, &gss_credops);
	/*
	 * Note: in order to force a call to call_refresh(), we deliberately
	 * fail to flag the credential as RPCAUTH_CRED_UPTODATE.
	 */
	cred->gc_base.cr_flags = 1UL << RPCAUTH_CRED_NEW;
	cred->gc_service = gss_auth->service;
	cred->gc_principal = acred->principal;
	kref_get(&gss_auth->kref);
	return &cred->gc_base;

out_err:
	return ERR_PTR(err);
}

static int
gss_cred_init(struct rpc_auth *auth, struct rpc_cred *cred)
{
	struct gss_auth *gss_auth = container_of(auth, struct gss_auth, rpc_auth);
	struct gss_cred *gss_cred = container_of(cred,struct gss_cred, gc_base);
	int err;

	do {
		err = gss_create_upcall(gss_auth, gss_cred);
	} while (err == -EAGAIN);
	return err;
}

static char *
gss_stringify_acceptor(struct rpc_cred *cred)
{
	char *string = NULL;
	struct gss_cred *gss_cred = container_of(cred, struct gss_cred, gc_base);
	struct gss_cl_ctx *ctx;
	unsigned int len;
	struct xdr_netobj *acceptor;

	rcu_read_lock();
	ctx = rcu_dereference(gss_cred->gc_ctx);
	if (!ctx)
		goto out;

	len = ctx->gc_acceptor.len;
	rcu_read_unlock();

	/* no point if there's no string */
	if (!len)
		return NULL;
realloc:
	string = kmalloc(len + 1, GFP_KERNEL);
	if (!string)
		return NULL;

	rcu_read_lock();
	ctx = rcu_dereference(gss_cred->gc_ctx);

	/* did the ctx disappear or was it replaced by one with no acceptor? */
	if (!ctx || !ctx->gc_acceptor.len) {
		kfree(string);
		string = NULL;
		goto out;
	}

	acceptor = &ctx->gc_acceptor;

	/*
	 * Did we find a new acceptor that's longer than the original? Allocate
	 * a longer buffer and try again.
	 */
	if (len < acceptor->len) {
		len = acceptor->len;
		rcu_read_unlock();
		kfree(string);
		goto realloc;
	}

	memcpy(string, acceptor->data, acceptor->len);
	string[acceptor->len] = '\0';
out:
	rcu_read_unlock();
	return string;
}

/*
 * Returns -EACCES if GSS context is NULL or will expire within the
 * timeout (miliseconds)
 */
static int
gss_key_timeout(struct rpc_cred *rc)
{
	struct gss_cred *gss_cred = container_of(rc, struct gss_cred, gc_base);
	struct gss_cl_ctx *ctx;
	unsigned long timeout = jiffies + (gss_key_expire_timeo * HZ);
	int ret = 0;

	rcu_read_lock();
	ctx = rcu_dereference(gss_cred->gc_ctx);
	if (!ctx || time_after(timeout, ctx->gc_expiry))
		ret = -EACCES;
	rcu_read_unlock();

	return ret;
}

static int
gss_match(struct auth_cred *acred, struct rpc_cred *rc, int flags)
{
	struct gss_cred *gss_cred = container_of(rc, struct gss_cred, gc_base);
	struct gss_cl_ctx *ctx;
	int ret;

	if (test_bit(RPCAUTH_CRED_NEW, &rc->cr_flags))
		goto out;
	/* Don't match with creds that have expired. */
	rcu_read_lock();
	ctx = rcu_dereference(gss_cred->gc_ctx);
	if (!ctx || time_after(jiffies, ctx->gc_expiry)) {
		rcu_read_unlock();
		return 0;
	}
	rcu_read_unlock();
	if (!test_bit(RPCAUTH_CRED_UPTODATE, &rc->cr_flags))
		return 0;
out:
	if (acred->principal != NULL) {
		if (gss_cred->gc_principal == NULL)
			return 0;
		ret = strcmp(acred->principal, gss_cred->gc_principal) == 0;
	} else {
		if (gss_cred->gc_principal != NULL)
			return 0;
		ret = uid_eq(rc->cr_cred->fsuid, acred->cred->fsuid);
	}
	return ret;
}

/*
 * Marshal credentials.
 *
 * The expensive part is computing the verifier. We can't cache a
 * pre-computed version of the verifier because the seqno, which
 * is different every time, is included in the MIC.
 */
static int gss_marshal(struct rpc_task *task, struct xdr_stream *xdr)
{
	struct rpc_rqst *req = task->tk_rqstp;
	struct rpc_cred *cred = req->rq_cred;
	struct gss_cred	*gss_cred = container_of(cred, struct gss_cred,
						 gc_base);
	struct gss_cl_ctx	*ctx = gss_cred_get_ctx(cred);
	__be32		*p, *cred_len;
	u32             maj_stat = 0;
	struct xdr_netobj mic;
	struct kvec	iov;
	struct xdr_buf	verf_buf;
	int status;
	u32 seqno;

	/* Credential */

	p = xdr_reserve_space(xdr, 7 * sizeof(*p) +
			      ctx->gc_wire_ctx.len);
	if (!p)
		goto marshal_failed;
	*p++ = rpc_auth_gss;
	cred_len = p++;

	spin_lock(&ctx->gc_seq_lock);
	seqno = (ctx->gc_seq < MAXSEQ) ? ctx->gc_seq++ : MAXSEQ;
	xprt_rqst_add_seqno(req, seqno);
	spin_unlock(&ctx->gc_seq_lock);
	if (*req->rq_seqnos == MAXSEQ)
		goto expired;
	trace_rpcgss_seqno(task);

	*p++ = cpu_to_be32(RPC_GSS_VERSION);
	*p++ = cpu_to_be32(ctx->gc_proc);
	*p++ = cpu_to_be32(*req->rq_seqnos);
	*p++ = cpu_to_be32(gss_cred->gc_service);
	p = xdr_encode_netobj(p, &ctx->gc_wire_ctx);
	*cred_len = cpu_to_be32((p - (cred_len + 1)) << 2);

	/* Verifier */

	/* We compute the checksum for the verifier over the xdr-encoded bytes
	 * starting with the xid and ending at the end of the credential: */
	iov.iov_base = req->rq_snd_buf.head[0].iov_base;
	iov.iov_len = (u8 *)p - (u8 *)iov.iov_base;
	xdr_buf_from_iov(&iov, &verf_buf);

	p = xdr_reserve_space(xdr, sizeof(*p));
	if (!p)
		goto marshal_failed;
	*p++ = rpc_auth_gss;
	mic.data = (u8 *)(p + 1);
	maj_stat = gss_get_mic(ctx->gc_gss_ctx, &verf_buf, &mic);
	if (maj_stat == GSS_S_CONTEXT_EXPIRED)
		goto expired;
	else if (maj_stat != 0)
		goto bad_mic;
	if (xdr_stream_encode_opaque_inline(xdr, (void **)&p, mic.len) < 0)
		goto marshal_failed;
	status = 0;
out:
	gss_put_ctx(ctx);
	return status;
expired:
	clear_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
	status = -EKEYEXPIRED;
	goto out;
marshal_failed:
	status = -EMSGSIZE;
	goto out;
bad_mic:
	trace_rpcgss_get_mic(task, maj_stat);
	status = -EIO;
	goto out;
}

static int gss_renew_cred(struct rpc_task *task)
{
	struct rpc_cred *oldcred = task->tk_rqstp->rq_cred;
	struct gss_cred *gss_cred = container_of(oldcred,
						 struct gss_cred,
						 gc_base);
	struct rpc_auth *auth = oldcred->cr_auth;
	struct auth_cred acred = {
		.cred = oldcred->cr_cred,
		.principal = gss_cred->gc_principal,
	};
	struct rpc_cred *new;

	new = gss_lookup_cred(auth, &acred, RPCAUTH_LOOKUP_NEW);
	if (IS_ERR(new))
		return PTR_ERR(new);

	task->tk_rqstp->rq_cred = new;
	put_rpccred(oldcred);
	return 0;
}

static int gss_cred_is_negative_entry(struct rpc_cred *cred)
{
	if (test_bit(RPCAUTH_CRED_NEGATIVE, &cred->cr_flags)) {
		unsigned long now = jiffies;
		unsigned long begin, expire;
		struct gss_cred *gss_cred;

		gss_cred = container_of(cred, struct gss_cred, gc_base);
		begin = gss_cred->gc_upcall_timestamp;
		expire = begin + gss_expired_cred_retry_delay * HZ;

		if (time_in_range_open(now, begin, expire))
			return 1;
	}
	return 0;
}

/*
* Refresh credentials. XXX - finish
*/
static int
gss_refresh(struct rpc_task *task)
{
	struct rpc_cred *cred = task->tk_rqstp->rq_cred;
	int ret = 0;

	if (gss_cred_is_negative_entry(cred))
		return -EKEYEXPIRED;

	if (!test_bit(RPCAUTH_CRED_NEW, &cred->cr_flags) &&
			!test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags)) {
		ret = gss_renew_cred(task);
		if (ret < 0)
			goto out;
		cred = task->tk_rqstp->rq_cred;
	}

	if (test_bit(RPCAUTH_CRED_NEW, &cred->cr_flags))
		ret = gss_refresh_upcall(task);
out:
	return ret;
}

/* Dummy refresh routine: used only when destroying the context */
static int
gss_refresh_null(struct rpc_task *task)
{
	return 0;
}

static u32
gss_validate_seqno_mic(struct gss_cl_ctx *ctx, u32 seqno, __be32 *seq, __be32 *p, u32 len)
{
	struct kvec iov;
	struct xdr_buf verf_buf;
	struct xdr_netobj mic;

	*seq = cpu_to_be32(seqno);
	iov.iov_base = seq;
	iov.iov_len = 4;
	xdr_buf_from_iov(&iov, &verf_buf);
	mic.data = (u8 *)p;
	mic.len = len;
	return gss_verify_mic(ctx->gc_gss_ctx, &verf_buf, &mic);
}

static int
gss_validate(struct rpc_task *task, struct xdr_stream *xdr)
{
	struct rpc_cred *cred = task->tk_rqstp->rq_cred;
	struct gss_cl_ctx *ctx = gss_cred_get_ctx(cred);
	__be32		*p, *seq = NULL;
	u32		len, maj_stat;
	int		status;
	int		i = 1; /* don't recheck the first item */

	p = xdr_inline_decode(xdr, 2 * sizeof(*p));
	if (!p)
		goto validate_failed;
	if (*p++ != rpc_auth_gss)
		goto validate_failed;
	len = be32_to_cpup(p);
	if (len > RPC_MAX_AUTH_SIZE)
		goto validate_failed;
	p = xdr_inline_decode(xdr, len);
	if (!p)
		goto validate_failed;

	seq = kmalloc(4, GFP_KERNEL);
	if (!seq)
		goto validate_failed;
	maj_stat = gss_validate_seqno_mic(ctx, task->tk_rqstp->rq_seqnos[0], seq, p, len);
	/* RFC 2203 5.3.3.1 - compute the checksum of each sequence number in the cache */
	while (unlikely(maj_stat == GSS_S_BAD_SIG && i < task->tk_rqstp->rq_seqno_count))
		maj_stat = gss_validate_seqno_mic(ctx, task->tk_rqstp->rq_seqnos[i++], seq, p, len);
	if (maj_stat == GSS_S_CONTEXT_EXPIRED)
		clear_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
	if (maj_stat)
		goto bad_mic;

	/* We leave it to unwrap to calculate au_rslack. For now we just
	 * calculate the length of the verifier: */
	if (test_bit(RPCAUTH_AUTH_UPDATE_SLACK, &cred->cr_auth->au_flags))
		cred->cr_auth->au_verfsize = XDR_QUADLEN(len) + 2;
	status = 0;
out:
	gss_put_ctx(ctx);
	kfree(seq);
	return status;

validate_failed:
	status = -EIO;
	goto out;
bad_mic:
	trace_rpcgss_verify_mic(task, maj_stat);
	status = -EACCES;
	goto out;
}

static noinline_for_stack int
gss_wrap_req_integ(struct rpc_cred *cred, struct gss_cl_ctx *ctx,
		   struct rpc_task *task, struct xdr_stream *xdr)
{
	struct rpc_rqst *rqstp = task->tk_rqstp;
	struct xdr_buf integ_buf, *snd_buf = &rqstp->rq_snd_buf;
	struct xdr_netobj mic;
	__be32 *p, *integ_len;
	u32 offset, maj_stat;

	p = xdr_reserve_space(xdr, 2 * sizeof(*p));
	if (!p)
		goto wrap_failed;
	integ_len = p++;
	*p = cpu_to_be32(*rqstp->rq_seqnos);

	if (rpcauth_wrap_req_encode(task, xdr))
		goto wrap_failed;

	offset = (u8 *)p - (u8 *)snd_buf->head[0].iov_base;
	if (xdr_buf_subsegment(snd_buf, &integ_buf,
				offset, snd_buf->len - offset))
		goto wrap_failed;
	*integ_len = cpu_to_be32(integ_buf.len);

	p = xdr_reserve_space(xdr, 0);
	if (!p)
		goto wrap_failed;
	mic.data = (u8 *)(p + 1);
	maj_stat = gss_get_mic(ctx->gc_gss_ctx, &integ_buf, &mic);
	if (maj_stat == GSS_S_CONTEXT_EXPIRED)
		clear_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
	else if (maj_stat)
		goto bad_mic;
	/* Check that the trailing MIC fit in the buffer, after the fact */
	if (xdr_stream_encode_opaque_inline(xdr, (void **)&p, mic.len) < 0)
		goto wrap_failed;
	return 0;
wrap_failed:
	return -EMSGSIZE;
bad_mic:
	trace_rpcgss_get_mic(task, maj_stat);
	return -EIO;
}

static void
priv_release_snd_buf(struct rpc_rqst *rqstp)
{
	int i;

	for (i=0; i < rqstp->rq_enc_pages_num; i++)
		__free_page(rqstp->rq_enc_pages[i]);
	kfree(rqstp->rq_enc_pages);
	rqstp->rq_release_snd_buf = NULL;
}

static int
alloc_enc_pages(struct rpc_rqst *rqstp)
{
	struct xdr_buf *snd_buf = &rqstp->rq_snd_buf;
	int first, last, i;

	if (rqstp->rq_release_snd_buf)
		rqstp->rq_release_snd_buf(rqstp);

	if (snd_buf->page_len == 0) {
		rqstp->rq_enc_pages_num = 0;
		return 0;
	}

	first = snd_buf->page_base >> PAGE_SHIFT;
	last = (snd_buf->page_base + snd_buf->page_len - 1) >> PAGE_SHIFT;
	rqstp->rq_enc_pages_num = last - first + 1 + 1;
	rqstp->rq_enc_pages
		= kmalloc_objs(struct page *, rqstp->rq_enc_pages_num);
	if (!rqstp->rq_enc_pages)
		goto out;
	for (i=0; i < rqstp->rq_enc_pages_num; i++) {
		rqstp->rq_enc_pages[i] = alloc_page(GFP_KERNEL);
		if (rqstp->rq_enc_pages[i] == NULL)
			goto out_free;
	}
	rqstp->rq_release_snd_buf = priv_release_snd_buf;
	return 0;
out_free:
	rqstp->rq_enc_pages_num = i;
	priv_release_snd_buf(rqstp);
out:
	return -EAGAIN;
}

static noinline_for_stack int
gss_wrap_req_priv(struct rpc_cred *cred, struct gss_cl_ctx *ctx,
		  struct rpc_task *task, struct xdr_stream *xdr)
{
	struct rpc_rqst *rqstp = task->tk_rqstp;
	struct xdr_buf	*snd_buf = &rqstp->rq_snd_buf;
	u32		pad, offset, maj_stat;
	int		status;
	__be32		*p, *opaque_len;
	struct page	**inpages;
	int		first;
	struct kvec	*iov;

	status = -EIO;
	p = xdr_reserve_space(xdr, 2 * sizeof(*p));
	if (!p)
		goto wrap_failed;
	opaque_len = p++;
	*p = cpu_to_be32(*rqstp->rq_seqnos);

	if (rpcauth_wrap_req_encode(task, xdr))
		goto wrap_failed;

	status = alloc_enc_pages(rqstp);
	if (unlikely(status))
		goto wrap_failed;
	first = snd_buf->page_base >> PAGE_SHIFT;
	inpages = snd_buf->pages + first;
	snd_buf->pages = rqstp->rq_enc_pages;
	snd_buf->page_base -= first << PAGE_SHIFT;
	/*
	 * Move the tail into its own page, in case gss_wrap needs
	 * more space in the head when wrapping.
	 *
	 * Still... Why can't gss_wrap just slide the tail down?
	 */
	if (snd_buf->page_len || snd_buf->tail[0].iov_len) {
		char *tmp;

		tmp = page_address(rqstp->rq_enc_pages[rqstp->rq_enc_pages_num - 1]);
		memcpy(tmp, snd_buf->tail[0].iov_base, snd_buf->tail[0].iov_len);
		snd_buf->tail[0].iov_base = tmp;
	}
	offset = (u8 *)p - (u8 *)snd_buf->head[0].iov_base;
	maj_stat = gss_wrap(ctx->gc_gss_ctx, offset, snd_buf, inpages);
	/* slack space should prevent this ever happening: */
	if (unlikely(snd_buf->len > snd_buf->buflen)) {
		status = -EIO;
		goto wrap_failed;
	}
	/* We're assuming that when GSS_S_CONTEXT_EXPIRED, the encryption was
	 * done anyway, so it's safe to put the request on the wire: */
	if (maj_stat == GSS_S_CONTEXT_EXPIRED)
		clear_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
	else if (maj_stat)
		goto bad_wrap;

	*opaque_len = cpu_to_be32(snd_buf->len - offset);
	/* guess whether the pad goes into the head or the tail: */
	if (snd_buf->page_len || snd_buf->tail[0].iov_len)
		iov = snd_buf->tail;
	else
		iov = snd_buf->head;
	p = iov->iov_base + iov->iov_len;
	pad = xdr_pad_size(snd_buf->len - offset);
	memset(p, 0, pad);
	iov->iov_len += pad;
	snd_buf->len += pad;

	return 0;
wrap_failed:
	return status;
bad_wrap:
	trace_rpcgss_wrap(task, maj_stat);
	return -EIO;
}

static int gss_wrap_req(struct rpc_task *task, struct xdr_stream *xdr)
{
	struct rpc_cred *cred = task->tk_rqstp->rq_cred;
	struct gss_cred	*gss_cred = container_of(cred, struct gss_cred,
			gc_base);
	struct gss_cl_ctx *ctx = gss_cred_get_ctx(cred);
	int status;

	status = -EIO;
	if (ctx->gc_proc != RPC_GSS_PROC_DATA) {
		/* The spec seems a little ambiguous here, but I think that not
		 * wrapping context destruction requests makes the most sense.
		 */
		status = rpcauth_wrap_req_encode(task, xdr);
		goto out;
	}
	switch (gss_cred->gc_service) {
	case RPC_GSS_SVC_NONE:
		status = rpcauth_wrap_req_encode(task, xdr);
		break;
	case RPC_GSS_SVC_INTEGRITY:
		status = gss_wrap_req_integ(cred, ctx, task, xdr);
		break;
	case RPC_GSS_SVC_PRIVACY:
		status = gss_wrap_req_priv(cred, ctx, task, xdr);
		break;
	default:
		status = -EIO;
	}
out:
	gss_put_ctx(ctx);
	return status;
}

/**
 * gss_update_rslack - Possibly update RPC receive buffer size estimates
 * @task: rpc_task for incoming RPC Reply being unwrapped
 * @cred: controlling rpc_cred for @task
 * @before: XDR words needed before each RPC Reply message
 * @after: XDR words needed following each RPC Reply message
 *
 */
static void gss_update_rslack(struct rpc_task *task, struct rpc_cred *cred,
			      unsigned int before, unsigned int after)
{
	struct rpc_auth *auth = cred->cr_auth;

	if (test_and_clear_bit(RPCAUTH_AUTH_UPDATE_SLACK, &auth->au_flags)) {
		auth->au_ralign = auth->au_verfsize + before;
		auth->au_rslack = auth->au_verfsize + after;
		trace_rpcgss_update_slack(task, auth);
	}
}

static int
gss_unwrap_resp_auth(struct rpc_task *task, struct rpc_cred *cred)
{
	gss_update_rslack(task, cred, 0, 0);
	return 0;
}

/*
 * RFC 2203, Section 5.3.2.2
 *
 *	struct rpc_gss_integ_data {
 *		opaque databody_integ<>;
 *		opaque checksum<>;
 *	};
 *
 *	struct rpc_gss_data_t {
 *		unsigned int seq_num;
 *		proc_req_arg_t arg;
 *	};
 */
static noinline_for_stack int
gss_unwrap_resp_integ(struct rpc_task *task, struct rpc_cred *cred,
		      struct gss_cl_ctx *ctx, struct rpc_rqst *rqstp,
		      struct xdr_stream *xdr)
{
	struct xdr_buf gss_data, *rcv_buf = &rqstp->rq_rcv_buf;
	u32 len, offset, seqno, maj_stat;
	struct xdr_netobj mic;
	int ret;

	ret = -EIO;
	mic.data = NULL;

	/* opaque databody_integ<>; */
	if (xdr_stream_decode_u32(xdr, &len))
		goto unwrap_failed;
	if (len & 3)
		goto unwrap_failed;
	offset = rcv_buf->len - xdr_stream_remaining(xdr);
	if (xdr_stream_decode_u32(xdr, &seqno))
		goto unwrap_failed;
	if (seqno != *rqstp->rq_seqnos)
		goto bad_seqno;
	if (xdr_buf_subsegment(rcv_buf, &gss_data, offset, len))
		goto unwrap_failed;

	/*
	 * The xdr_stream now points to the beginning of the
	 * upper layer payload, to be passed below to
	 * rpcauth_unwrap_resp_decode(). The checksum, which
	 * follows the upper layer payload in @rcv_buf, is
	 * located and parsed without updating the xdr_stream.
	 */

	/* opaque checksum<>; */
	offset += len;
	if (xdr_decode_word(rcv_buf, offset, &len))
		goto unwrap_failed;
	offset += sizeof(__be32);
	if (offset + len > rcv_buf->len)
		goto unwrap_failed;
	mic.len = len;
	mic.data = kmalloc(len, GFP_KERNEL);
	if (ZERO_OR_NULL_PTR(mic.data))
		goto unwrap_failed;
	if (read_bytes_from_xdr_buf(rcv_buf, offset, mic.data, mic.len))
		goto unwrap_failed;

	maj_stat = gss_verify_mic(ctx->gc_gss_ctx, &gss_data, &mic);
	if (maj_stat == GSS_S_CONTEXT_EXPIRED)
		clear_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
	if (maj_stat != GSS_S_COMPLETE)
		goto bad_mic;

	gss_update_rslack(task, cred, 2, 2 + 1 + XDR_QUADLEN(mic.len));
	ret = 0;

out:
	kfree(mic.data);
	return ret;

unwrap_failed:
	trace_rpcgss_unwrap_failed(task);
	goto out;
bad_seqno:
	trace_rpcgss_bad_seqno(task, *rqstp->rq_seqnos, seqno);
	goto out;
bad_mic:
	trace_rpcgss_verify_mic(task, maj_stat);
	goto out;
}

static noinline_for_stack int
gss_unwrap_resp_priv(struct rpc_task *task, struct rpc_cred *cred,
		     struct gss_cl_ctx *ctx, struct rpc_rqst *rqstp,
		     struct xdr_stream *xdr)
{
	struct xdr_buf *rcv_buf = &rqstp->rq_rcv_buf;
	struct kvec *head = rqstp->rq_rcv_buf.head;
	u32 offset, opaque_len, maj_stat;
	__be32 *p;

	p = xdr_inline_decode(xdr, 2 * sizeof(*p));
	if (unlikely(!p))
		goto unwrap_failed;
	opaque_len = be32_to_cpup(p++);
	offset = (u8 *)(p) - (u8 *)head->iov_base;
	if (offset + opaque_len > rcv_buf->len)
		goto unwrap_failed;

	maj_stat = gss_unwrap(ctx->gc_gss_ctx, offset,
			      offset + opaque_len, rcv_buf);
	if (maj_stat == GSS_S_CONTEXT_EXPIRED)
		clear_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
	if (maj_stat != GSS_S_COMPLETE)
		goto bad_unwrap;
	/* gss_unwrap decrypted the sequence number */
	if (be32_to_cpup(p++) != *rqstp->rq_seqnos)
		goto bad_seqno;

	/* gss_unwrap redacts the opaque blob from the head iovec.
	 * rcv_buf has changed, thus the stream needs to be reset.
	 */
	xdr_init_decode(xdr, rcv_buf, p, rqstp);

	gss_update_rslack(task, cred, 2 + ctx->gc_gss_ctx->align,
			  2 + ctx->gc_gss_ctx->slack);

	return 0;
unwrap_failed:
	trace_rpcgss_unwrap_failed(task);
	return -EIO;
bad_seqno:
	trace_rpcgss_bad_seqno(task, *rqstp->rq_seqnos, be32_to_cpup(--p));
	return -EIO;
bad_unwrap:
	trace_rpcgss_unwrap(task, maj_stat);
	return -EIO;
}

static bool
gss_seq_is_newer(u32 new, u32 old)
{
	return (s32)(new - old) > 0;
}

static bool
gss_xmit_need_reencode(struct rpc_task *task)
{
	struct rpc_rqst *req = task->tk_rqstp;
	struct rpc_cred *cred = req->rq_cred;
	struct gss_cl_ctx *ctx = gss_cred_get_ctx(cred);
	u32 win, seq_xmit = 0;
	bool ret = true;

	if (!ctx)
		goto out;

	if (gss_seq_is_newer(*req->rq_seqnos, READ_ONCE(ctx->gc_seq)))
		goto out_ctx;

	seq_xmit = READ_ONCE(ctx->gc_seq_xmit);
	while (gss_seq_is_newer(*req->rq_seqnos, seq_xmit)) {
		u32 tmp = seq_xmit;

		seq_xmit = cmpxchg(&ctx->gc_seq_xmit, tmp, *req->rq_seqnos);
		if (seq_xmit == tmp) {
			ret = false;
			goto out_ctx;
		}
	}

	win = ctx->gc_win;
	if (win > 0)
		ret = !gss_seq_is_newer(*req->rq_seqnos, seq_xmit - win);

out_ctx:
	gss_put_ctx(ctx);
out:
	trace_rpcgss_need_reencode(task, seq_xmit, ret);
	return ret;
}

static int
gss_unwrap_resp(struct rpc_task *task, struct xdr_stream *xdr)
{
	struct rpc_rqst *rqstp = task->tk_rqstp;
	struct rpc_cred *cred = rqstp->rq_cred;
	struct gss_cred *gss_cred = container_of(cred, struct gss_cred,
			gc_base);
	struct gss_cl_ctx *ctx = gss_cred_get_ctx(cred);
	int status = -EIO;

	if (ctx->gc_proc != RPC_GSS_PROC_DATA)
		goto out_decode;
	switch (gss_cred->gc_service) {
	case RPC_GSS_SVC_NONE:
		status = gss_unwrap_resp_auth(task, cred);
		break;
	case RPC_GSS_SVC_INTEGRITY:
		status = gss_unwrap_resp_integ(task, cred, ctx, rqstp, xdr);
		break;
	case RPC_GSS_SVC_PRIVACY:
		status = gss_unwrap_resp_priv(task, cred, ctx, rqstp, xdr);
		break;
	}
	if (status)
		goto out;

out_decode:
	status = rpcauth_unwrap_resp_decode(task, xdr);
out:
	gss_put_ctx(ctx);
	return status;
}

static const struct rpc_authops authgss_ops = {
	.owner		= THIS_MODULE,
	.au_flavor	= RPC_AUTH_GSS,
	.au_name	= "RPCSEC_GSS",
	.create		= gss_create,
	.destroy	= gss_destroy,
	.hash_cred	= gss_hash_cred,
	.lookup_cred	= gss_lookup_cred,
	.crcreate	= gss_create_cred,
	.info2flavor	= gss_mech_info2flavor,
	.flavor2info	= gss_mech_flavor2info,
};

static const struct rpc_credops gss_credops = {
	.cr_name		= "AUTH_GSS",
	.crdestroy		= gss_destroy_cred,
	.cr_init		= gss_cred_init,
	.crmatch		= gss_match,
	.crmarshal		= gss_marshal,
	.crrefresh		= gss_refresh,
	.crvalidate		= gss_validate,
	.crwrap_req		= gss_wrap_req,
	.crunwrap_resp		= gss_unwrap_resp,
	.crkey_timeout		= gss_key_timeout,
	.crstringify_acceptor	= gss_stringify_acceptor,
	.crneed_reencode	= gss_xmit_need_reencode,
};

static const struct rpc_credops gss_nullops = {
	.cr_name		= "AUTH_GSS",
	.crdestroy		= gss_destroy_nullcred,
	.crmatch		= gss_match,
	.crmarshal		= gss_marshal,
	.crrefresh		= gss_refresh_null,
	.crvalidate		= gss_validate,
	.crwrap_req		= gss_wrap_req,
	.crunwrap_resp		= gss_unwrap_resp,
	.crstringify_acceptor	= gss_stringify_acceptor,
};

static const struct rpc_pipe_ops gss_upcall_ops_v0 = {
	.upcall		= gss_v0_upcall,
	.downcall	= gss_pipe_downcall,
	.destroy_msg	= gss_pipe_destroy_msg,
	.open_pipe	= gss_pipe_open_v0,
	.release_pipe	= gss_pipe_release,
};

static const struct rpc_pipe_ops gss_upcall_ops_v1 = {
	.upcall		= gss_v1_upcall,
	.downcall	= gss_pipe_downcall,
	.destroy_msg	= gss_pipe_destroy_msg,
	.open_pipe	= gss_pipe_open_v1,
	.release_pipe	= gss_pipe_release,
};

static __net_init int rpcsec_gss_init_net(struct net *net)
{
	return gss_svc_init_net(net);
}

static __net_exit void rpcsec_gss_exit_net(struct net *net)
{
	gss_svc_shutdown_net(net);
}

static struct pernet_operations rpcsec_gss_net_ops = {
	.init = rpcsec_gss_init_net,
	.exit = rpcsec_gss_exit_net,
};

/*
 * Initialize RPCSEC_GSS module
 */
static int __init init_rpcsec_gss(void)
{
	int err = 0;

	err = rpcauth_register(&authgss_ops);
	if (err)
		goto out;
	err = gss_svc_init();
	if (err)
		goto out_unregister;
	err = register_pernet_subsys(&rpcsec_gss_net_ops);
	if (err)
		goto out_svc_exit;
	rpc_init_wait_queue(&pipe_version_rpc_waitqueue, "gss pipe version");
	return 0;
out_svc_exit:
	gss_svc_shutdown();
out_unregister:
	rpcauth_unregister(&authgss_ops);
out:
	return err;
}

static void __exit exit_rpcsec_gss(void)
{
	unregister_pernet_subsys(&rpcsec_gss_net_ops);
	gss_svc_shutdown();
	rpcauth_unregister(&authgss_ops);
	rcu_barrier(); /* Wait for completion of call_rcu()'s */
}

MODULE_ALIAS("rpc-auth-6");
MODULE_DESCRIPTION("Sun RPC Kerberos RPCSEC_GSS client authentication");
MODULE_LICENSE("GPL");
module_param_named(expired_cred_retry_delay,
		   gss_expired_cred_retry_delay,
		   uint, 0644);
MODULE_PARM_DESC(expired_cred_retry_delay, "Timeout (in seconds) until "
		"the RPC engine retries an expired credential");

module_param_named(key_expire_timeo,
		   gss_key_expire_timeo,
		   uint, 0644);
MODULE_PARM_DESC(key_expire_timeo, "Time (in seconds) at the end of a "
		"credential keys lifetime where the NFS layer cleans up "
		"prior to key expiration");

module_init(init_rpcsec_gss)
module_exit(exit_rpcsec_gss)
