auth_gss.c

/*
 * 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>
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *
 *  1. Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *  3. Neither the name of the University nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
 *  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 *  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 *  DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 *  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 *  BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 *  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 *  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 *  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */


#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/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 <asm/uaccess.h>

static const struct rpc_authops authgss_ops;

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

#define GSS_RETRY_EXPIRED 5
static unsigned int gss_expired_cred_retry_delay = GSS_RETRY_EXPIRED;

#ifdef RPC_DEBUG
# define RPCDBG_FACILITY	RPCDBG_AUTH
#endif

#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

struct gss_auth {
	struct kref kref;
	struct rpc_auth rpc_auth;
	struct gss_api_mech *mech;
	enum rpc_gss_svc service;
	struct rpc_clnt *client;
	/*
	 * 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 dentry *dentry[2];
};

/* pipe_version >= 0 if and only if someone has a pipe open. */
static int pipe_version = -1;
static atomic_t pipe_users = ATOMIC_INIT(0);
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_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)
{
	atomic_inc(&ctx->count);
	return ctx;
}

static inline void
gss_put_ctx(struct gss_cl_ctx *ctx)
{
	if (atomic_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 inode->i_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_INIT_POINTER(gss_cred->gc_ctx, ctx);
	set_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
	smp_mb__before_clear_bit();
	clear_bit(RPCAUTH_CRED_NEW, &cred->cr_flags);
}

static const void *
simple_get_bytes(const void *p, const void *end, void *res, size_t len)
{
	const void *q = (const void *)((const char *)p + len);
	if (unlikely(q > end || q < p))
		return ERR_PTR(-EFAULT);
	memcpy(res, p, len);
	return q;
}

static inline const void *
simple_get_netobj(const void *p, const void *end, struct xdr_netobj *dest)
{
	const void *q;
	unsigned int len;

	p = simple_get_bytes(p, end, &len, sizeof(len));
	if (IS_ERR(p))
		return p;
	q = (const void *)((const char *)p + len);
	if (unlikely(q > end || q < p))
		return ERR_PTR(-EFAULT);
	dest->data = kmemdup(p, len, GFP_NOFS);
	if (unlikely(dest->data == NULL))
		return ERR_PTR(-ENOMEM);
	dest->len = len;
	return q;
}

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

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

	ctx = kzalloc(sizeof(*ctx), GFP_NOFS);
	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);
		atomic_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;
	u32 window_size;
	int ret;

	/* First unsigned int gives the lifetime (in seconds) of the cred */
	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 = jiffies + (unsigned long)timeout * HZ * 3 / 4;
	/* 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, GFP_NOFS);
	if (ret < 0) {
		p = ERR_PTR(ret);
		goto err;
	}
	return q;
err:
	dprintk("RPC:       gss_fill_context returning %ld\n", -PTR_ERR(p));
	return p;
}

#define UPCALL_BUF_LEN 128

struct gss_upcall_msg {
	atomic_t count;
	uid_t	uid;
	struct rpc_pipe_msg msg;
	struct list_head list;
	struct gss_auth *auth;
	struct rpc_inode *inode;
	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(void)
{
	int ret;

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

static void put_pipe_version(void)
{
	if (atomic_dec_and_lock(&pipe_users, &pipe_version_lock)) {
		pipe_version = -1;
		spin_unlock(&pipe_version_lock);
	}
}

static void
gss_release_msg(struct gss_upcall_msg *gss_msg)
{
	if (!atomic_dec_and_test(&gss_msg->count))
		return;
	put_pipe_version();
	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);
	kfree(gss_msg);
}

static struct gss_upcall_msg *
__gss_find_upcall(struct rpc_inode *rpci, uid_t uid)
{
	struct gss_upcall_msg *pos;
	list_for_each_entry(pos, &rpci->in_downcall, list) {
		if (pos->uid != uid)
			continue;
		atomic_inc(&pos->count);
		dprintk("RPC:       gss_find_upcall found msg %p\n", pos);
		return pos;
	}
	dprintk("RPC:       gss_find_upcall found nothing\n");
	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_inode *rpci = gss_msg->inode;
	struct inode *inode = &rpci->vfs_inode;
	struct gss_upcall_msg *old;

	spin_lock(&inode->i_lock);
	old = __gss_find_upcall(rpci, gss_msg->uid);
	if (old == NULL) {
		atomic_inc(&gss_msg->count);
		list_add(&gss_msg->list, &rpci->in_downcall);
	} else
		gss_msg = old;
	spin_unlock(&inode->i_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);
	atomic_dec(&gss_msg->count);
}

static void
gss_unhash_msg(struct gss_upcall_msg *gss_msg)
{
	struct inode *inode = &gss_msg->inode->vfs_inode;

	if (list_empty(&gss_msg->list))
		return;
	spin_lock(&inode->i_lock);
	if (!list_empty(&gss_msg->list))
		__gss_unhash_msg(gss_msg);
	spin_unlock(&inode->i_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 inode *inode = &gss_msg->inode->vfs_inode;

	spin_lock(&inode->i_lock);
	gss_handle_downcall_result(gss_cred, gss_msg);
	spin_unlock(&inode->i_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)
{
	gss_msg->msg.data = &gss_msg->uid;
	gss_msg->msg.len = sizeof(gss_msg->uid);
}

static void gss_encode_v1_msg(struct gss_upcall_msg *gss_msg,
				struct rpc_clnt *clnt, int machine_cred)
{
	struct gss_api_mech *mech = gss_msg->auth->mech;
	char *p = gss_msg->databuf;
	int len = 0;

	gss_msg->msg.len = sprintf(gss_msg->databuf, "mech=%s uid=%d ",
				   mech->gm_name,
				   gss_msg->uid);
	p += gss_msg->msg.len;
	if (clnt->cl_principal) {
		len = sprintf(p, "target=%s ", clnt->cl_principal);
		p += len;
		gss_msg->msg.len += len;
	}
	if (machine_cred) {
		len = sprintf(p, "service=* ");
		p += len;
		gss_msg->msg.len += len;
	} else if (!strcmp(clnt->cl_program->name, "nfs4_cb")) {
		len = sprintf(p, "service=nfs ");
		p += len;
		gss_msg->msg.len += len;
	}
	if (mech->gm_upcall_enctypes) {
		len = sprintf(p, "enctypes=%s ", mech->gm_upcall_enctypes);
		p += len;
		gss_msg->msg.len += len;
	}
	len = sprintf(p, "\n");
	gss_msg->msg.len += len;

	gss_msg->msg.data = gss_msg->databuf;
	BUG_ON(gss_msg->msg.len > UPCALL_BUF_LEN);
}

static void gss_encode_msg(struct gss_upcall_msg *gss_msg,
				struct rpc_clnt *clnt, int machine_cred)
{
	if (pipe_version == 0)
		gss_encode_v0_msg(gss_msg);
	else /* pipe_version == 1 */
		gss_encode_v1_msg(gss_msg, clnt, machine_cred);
}

static inline struct gss_upcall_msg *
gss_alloc_msg(struct gss_auth *gss_auth, uid_t uid, struct rpc_clnt *clnt,
		int machine_cred)
{
	struct gss_upcall_msg *gss_msg;
	int vers;

	gss_msg = kzalloc(sizeof(*gss_msg), GFP_NOFS);
	if (gss_msg == NULL)
		return ERR_PTR(-ENOMEM);
	vers = get_pipe_version();
	if (vers < 0) {
		kfree(gss_msg);
		return ERR_PTR(vers);
	}
	gss_msg->inode = RPC_I(gss_auth->dentry[vers]->d_inode);
	INIT_LIST_HEAD(&gss_msg->list);
	rpc_init_wait_queue(&gss_msg->rpc_waitqueue, "RPCSEC_GSS upcall waitq");
	init_waitqueue_head(&gss_msg->waitqueue);
	atomic_set(&gss_msg->count, 1);
	gss_msg->uid = uid;
	gss_msg->auth = gss_auth;
	gss_encode_msg(gss_msg, clnt, machine_cred);
	return gss_msg;
}

static struct gss_upcall_msg *
gss_setup_upcall(struct rpc_clnt *clnt, 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;
	uid_t uid = cred->cr_uid;

	gss_new = gss_alloc_msg(gss_auth, uid, clnt, gss_cred->gc_machine_cred);
	if (IS_ERR(gss_new))
		return gss_new;
	gss_msg = gss_add_msg(gss_new);
	if (gss_msg == gss_new) {
		struct inode *inode = &gss_new->inode->vfs_inode;
		int res = rpc_queue_upcall(inode, &gss_new->msg);
		if (res) {
			gss_unhash_msg(gss_new);
			gss_msg = ERR_PTR(res);
		}
	} else
		gss_release_msg(gss_new);
	return gss_msg;
}

static void warn_gssd(void)
{
	static unsigned long ratelimit;
	unsigned long now = jiffies;

	if (time_after(now, ratelimit)) {
		printk(KERN_WARNING "RPC: AUTH_GSS upcall timed out.\n"
				"Please check user daemon is running.\n");
		ratelimit = now + 15*HZ;
	}
}

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 inode *inode;
	int err = 0;

	dprintk("RPC: %5u gss_refresh_upcall for uid %u\n", task->tk_pid,
								cred->cr_uid);
	gss_msg = gss_setup_upcall(task->tk_client, 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();
		task->tk_timeout = 15*HZ;
		rpc_sleep_on(&pipe_version_rpc_waitqueue, task, NULL);
		return -EAGAIN;
	}
	if (IS_ERR(gss_msg)) {
		err = PTR_ERR(gss_msg);
		goto out;
	}
	inode = &gss_msg->inode->vfs_inode;
	spin_lock(&inode->i_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) {
		task->tk_timeout = 0;
		gss_cred->gc_upcall = gss_msg;
		/* gss_upcall_callback will release the reference to gss_upcall_msg */
		atomic_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(&inode->i_lock);
	gss_release_msg(gss_msg);
out:
	dprintk("RPC: %5u gss_refresh_upcall for uid %u result %d\n",
			task->tk_pid, cred->cr_uid, err);
	return err;
}

static inline int
gss_create_upcall(struct gss_auth *gss_auth, struct gss_cred *gss_cred)
{
	struct inode *inode;
	struct rpc_cred *cred = &gss_cred->gc_base;
	struct gss_upcall_msg *gss_msg;
	DEFINE_WAIT(wait);
	int err = 0;

	dprintk("RPC:       gss_upcall for uid %u\n", cred->cr_uid);
retry:
	gss_msg = gss_setup_upcall(gss_auth->client, gss_auth, cred);
	if (PTR_ERR(gss_msg) == -EAGAIN) {
		err = wait_event_interruptible_timeout(pipe_version_waitqueue,
				pipe_version >= 0, 15*HZ);
		if (pipe_version < 0) {
			warn_gssd();
			err = -EACCES;
		}
		if (err)
			goto out;
		goto retry;
	}
	if (IS_ERR(gss_msg)) {
		err = PTR_ERR(gss_msg);
		goto out;
	}
	inode = &gss_msg->inode->vfs_inode;
	for (;;) {
		prepare_to_wait(&gss_msg->waitqueue, &wait, TASK_KILLABLE);
		spin_lock(&inode->i_lock);
		if (gss_msg->ctx != NULL || gss_msg->msg.errno < 0) {
			break;
		}
		spin_unlock(&inode->i_lock);
		if (fatal_signal_pending(current)) {
			err = -ERESTARTSYS;
			goto out_intr;
		}
		schedule();
	}
	if (gss_msg->ctx)
		gss_cred_set_ctx(cred, gss_msg->ctx);
	else
		err = gss_msg->msg.errno;
	spin_unlock(&inode->i_lock);
out_intr:
	finish_wait(&gss_msg->waitqueue, &wait);
	gss_release_msg(gss_msg);
out:
	dprintk("RPC:       gss_create_upcall for uid %u result %d\n",
			cred->cr_uid, err);
	return err;
}

#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 inode *inode = filp->f_path.dentry->d_inode;
	struct gss_cl_ctx *ctx;
	uid_t uid;
	ssize_t err = -EFBIG;

	if (mlen > MSG_BUF_MAXSIZE)
		goto out;
	err = -ENOMEM;
	buf = kmalloc(mlen, GFP_NOFS);
	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, &uid, sizeof(uid));
	if (IS_ERR(p)) {
		err = PTR_ERR(p);
		goto err;
	}

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

	err = -ENOENT;
	/* Find a matching upcall */
	spin_lock(&inode->i_lock);
	gss_msg = __gss_find_upcall(RPC_I(inode), uid);
	if (gss_msg == NULL) {
		spin_unlock(&inode->i_lock);
		goto err_put_ctx;
	}
	list_del_init(&gss_msg->list);
	spin_unlock(&inode->i_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);
			BUG();
		}
		goto err_release_msg;
	}
	gss_msg->ctx = gss_get_ctx(ctx);
	err = mlen;

err_release_msg:
	spin_lock(&inode->i_lock);
	__gss_unhash_msg(gss_msg);
	spin_unlock(&inode->i_lock);
	gss_release_msg(gss_msg);
err_put_ctx:
	gss_put_ctx(ctx);
err:
	kfree(buf);
out:
	dprintk("RPC:       gss_pipe_downcall returning %Zd\n", err);
	return err;
}

static int gss_pipe_open(struct inode *inode, int new_version)
{
	int ret = 0;

	spin_lock(&pipe_version_lock);
	if (pipe_version < 0) {
		/* First open of any gss pipe determines the version: */
		pipe_version = new_version;
		rpc_wake_up(&pipe_version_rpc_waitqueue);
		wake_up(&pipe_version_waitqueue);
	} else if (pipe_version != new_version) {
		/* Trying to open a pipe of a different version */
		ret = -EBUSY;
		goto out;
	}
	atomic_inc(&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 rpc_inode *rpci = RPC_I(inode);
	struct gss_upcall_msg *gss_msg;

restart:
	spin_lock(&inode->i_lock);
	list_for_each_entry(gss_msg, &rpci->in_downcall, list) {

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

	put_pipe_version();
}

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) {
		dprintk("RPC:       gss_pipe_destroy_msg releasing msg %p\n",
				gss_msg);
		atomic_inc(&gss_msg->count);
		gss_unhash_msg(gss_msg);
		if (msg->errno == -ETIMEDOUT)
			warn_gssd();
		gss_release_msg(gss_msg);
	}
}

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

	dprintk("RPC:       creating GSS authenticator for client %p\n", clnt);

	if (!try_module_get(THIS_MODULE))
		return ERR_PTR(err);
	if (!(gss_auth = kmalloc(sizeof(*gss_auth), GFP_KERNEL)))
		goto out_dec;
	gss_auth->client = clnt;
	err = -EINVAL;
	gss_auth->mech = gss_mech_get_by_pseudoflavor(flavor);
	if (!gss_auth->mech) {
		printk(KERN_WARNING "%s: Pseudoflavor %d not found!\n",
				__func__, flavor);
		goto err_free;
	}
	gss_auth->service = gss_pseudoflavor_to_service(gss_auth->mech, flavor);
	if (gss_auth->service == 0)
		goto err_put_mech;
	auth = &gss_auth->rpc_auth;
	auth->au_cslack = GSS_CRED_SLACK >> 2;
	auth->au_rslack = GSS_VERF_SLACK >> 2;
	auth->au_ops = &authgss_ops;
	auth->au_flavor = flavor;
	atomic_set(&auth->au_count, 1);
	kref_init(&gss_auth->kref);

	/*
	 * 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_auth->dentry[1] = rpc_mkpipe(clnt->cl_path.dentry,
					 "gssd",
					 clnt, &gss_upcall_ops_v1,
					 RPC_PIPE_WAIT_FOR_OPEN);
	if (IS_ERR(gss_auth->dentry[1])) {
		err = PTR_ERR(gss_auth->dentry[1]);
		goto err_put_mech;
	}

	gss_auth->dentry[0] = rpc_mkpipe(clnt->cl_path.dentry,
					 gss_auth->mech->gm_name,
					 clnt, &gss_upcall_ops_v0,
					 RPC_PIPE_WAIT_FOR_OPEN);
	if (IS_ERR(gss_auth->dentry[0])) {
		err = PTR_ERR(gss_auth->dentry[0]);
		goto err_unlink_pipe_1;
	}
	err = rpcauth_init_credcache(auth);
	if (err)
		goto err_unlink_pipe_0;

	return auth;
err_unlink_pipe_0:
	rpc_unlink(gss_auth->dentry[0]);
err_unlink_pipe_1:
	rpc_unlink(gss_auth->dentry[1]);
err_put_mech:
	gss_mech_put(gss_auth->mech);
err_free:
	kfree(gss_auth);
out_dec:
	module_put(THIS_MODULE);
	return ERR_PTR(err);
}

static void
gss_free(struct gss_auth *gss_auth)
{
	rpc_unlink(gss_auth->dentry[1]);
	rpc_unlink(gss_auth->dentry[0]);
	gss_mech_put(gss_auth->mech);

	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_destroy(struct rpc_auth *auth)
{
	struct gss_auth *gss_auth;

	dprintk("RPC:       destroying GSS authenticator %p flavor %d\n",
			auth, auth->au_flavor);

	rpcauth_destroy_credcache(auth);

	gss_auth = container_of(auth, struct gss_auth, rpc_auth);
	kref_put(&gss_auth->kref, gss_free_callback);
}

/*
 * gss_destroying_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 int
gss_destroying_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 rpc_task *task;

	if (gss_cred->gc_ctx == NULL ||
	    test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) == 0)
		return 0;

	gss_cred->gc_ctx->gc_proc = RPC_GSS_PROC_DESTROY;
	cred->cr_ops = &gss_nullops;

	/* Take a reference to ensure the cred will be destroyed either
	 * by the RPC call or by the put_rpccred() below */
	get_rpccred(cred);

	task = rpc_call_null(gss_auth->client, cred, RPC_TASK_ASYNC|RPC_TASK_SOFT);
	if (!IS_ERR(task))
		rpc_put_task(task);

	put_rpccred(cred);
	return 1;
}

/* 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)
{
	dprintk("RPC:       gss_free_ctx\n");

	gss_delete_sec_context(&ctx->gc_gss_ctx);
	kfree(ctx->gc_wire_ctx.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)
{
	dprintk("RPC:       gss_free_cred %p\n", 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 = gss_cred->gc_ctx;

	RCU_INIT_POINTER(gss_cred->gc_ctx, NULL);
	call_rcu(&cred->cr_rcu, gss_free_cred_callback);
	if (ctx)
		gss_put_ctx(ctx);
	kref_put(&gss_auth->kref, gss_free_callback);
}

static void
gss_destroy_cred(struct rpc_cred *cred)
{

	if (gss_destroying_context(cred))
		return;
	gss_destroy_nullcred(cred);
}

/*
 * 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);
}

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

	dprintk("RPC:       gss_create_cred for uid %d, flavor %d\n",
		acred->uid, auth->au_flavor);

	if (!(cred = kzalloc(sizeof(*cred), GFP_NOFS)))
		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_machine_cred = acred->machine_cred;
	kref_get(&gss_auth->kref);
	return &cred->gc_base;