/*
 * Neil Brown <neilb@cse.unsw.edu.au>
 * J. Bruce Fields <bfields@umich.edu>
 * Andy Adamson <andros@umich.edu>
 * Dug Song <dugsong@monkey.org>
 *
 * RPCSEC_GSS server authentication.
 * This implements RPCSEC_GSS as defined in rfc2203 (rpcsec_gss) and rfc2078
 * (gssapi)
 *
 * The RPCSEC_GSS involves three stages:
 *  1/ context creation
 *  2/ data exchange
 *  3/ context destruction
 *
 * Context creation is handled largely by upcalls to user-space.
 *  In particular, GSS_Accept_sec_context is handled by an upcall
 * Data exchange is handled entirely within the kernel
 *  In particular, GSS_GetMIC, GSS_VerifyMIC, GSS_Seal, GSS_Unseal are in-kernel.
 * Context destruction is handled in-kernel
 *  GSS_Delete_sec_context is in-kernel
 *
 * Context creation is initiated by a RPCSEC_GSS_INIT request arriving.
 * The context handle and gss_token are used as a key into the rpcsec_init cache.
 * The content of this cache includes some of the outputs of GSS_Accept_sec_context,
 * being major_status, minor_status, context_handle, reply_token.
 * These are sent back to the client.
 * Sequence window management is handled by the kernel.  The window size if currently
 * a compile time constant.
 *
 * When user-space is happy that a context is established, it places an entry
 * in the rpcsec_context cache. The key for this cache is the context_handle.
 * The content includes:
 *   uid/gidlist - for determining access rights
 *   mechanism type
 *   mechanism specific information, such as a key
 *
 */

#include <linux/types.h>
#include <linux/module.h>
#include <linux/pagemap.h>

#include <linux/sunrpc/auth_gss.h>
#include <linux/sunrpc/svcauth.h>
#include <linux/sunrpc/gss_err.h>
#include <linux/sunrpc/svcauth.h>
#include <linux/sunrpc/svcauth_gss.h>
#include <linux/sunrpc/cache.h>

#ifdef RPC_DEBUG
# define RPCDBG_FACILITY	RPCDBG_AUTH
#endif

/* The rpcsec_init cache is used for mapping RPCSEC_GSS_{,CONT_}INIT requests
 * into replies.
 *
 * Key is context handle (\x if empty) and gss_token.
 * Content is major_status minor_status (integers) context_handle, reply_token.
 *
 */

static int netobj_equal(struct xdr_netobj *a, struct xdr_netobj *b)
{
	return a->len == b->len && 0 == memcmp(a->data, b->data, a->len);
}

#define	RSI_HASHBITS	6
#define	RSI_HASHMAX	(1<<RSI_HASHBITS)
#define	RSI_HASHMASK	(RSI_HASHMAX-1)

struct rsi {
	struct cache_head	h;
	struct xdr_netobj	in_handle, in_token;
	struct xdr_netobj	out_handle, out_token;
	int			major_status, minor_status;
};

static struct cache_head *rsi_table[RSI_HASHMAX];
static struct cache_detail rsi_cache;
static struct rsi *rsi_lookup(struct rsi *item, int set);

static void rsi_free(struct rsi *rsii)
{
	kfree(rsii->in_handle.data);
	kfree(rsii->in_token.data);
	kfree(rsii->out_handle.data);
	kfree(rsii->out_token.data);
}

static void rsi_put(struct cache_head *item, struct cache_detail *cd)
{
	struct rsi *rsii = container_of(item, struct rsi, h);
	if (cache_put(item, cd)) {
		rsi_free(rsii);
		kfree(rsii);
	}
}

static inline int rsi_hash(struct rsi *item)
{
	return hash_mem(item->in_handle.data, item->in_handle.len, RSI_HASHBITS)
	     ^ hash_mem(item->in_token.data, item->in_token.len, RSI_HASHBITS);
}

static inline int rsi_match(struct rsi *item, struct rsi *tmp)
{
	return netobj_equal(&item->in_handle, &tmp->in_handle)
		&& netobj_equal(&item->in_token, &tmp->in_token);
}

static int dup_to_netobj(struct xdr_netobj *dst, char *src, int len)
{
	dst->len = len;
	dst->data = (len ? kmalloc(len, GFP_KERNEL) : NULL);
	if (dst->data)
		memcpy(dst->data, src, len);
	if (len && !dst->data)
		return -ENOMEM;
	return 0;
}

static inline int dup_netobj(struct xdr_netobj *dst, struct xdr_netobj *src)
{
	return dup_to_netobj(dst, src->data, src->len);
}

static inline void rsi_init(struct rsi *new, struct rsi *item)
{
	new->out_handle.data = NULL;
	new->out_handle.len = 0;
	new->out_token.data = NULL;
	new->out_token.len = 0;
	new->in_handle.len = item->in_handle.len;
	item->in_handle.len = 0;
	new->in_token.len = item->in_token.len;
	item->in_token.len = 0;
	new->in_handle.data = item->in_handle.data;
	item->in_handle.data = NULL;
	new->in_token.data = item->in_token.data;
	item->in_token.data = NULL;
}

static inline void rsi_update(struct rsi *new, struct rsi *item)
{
	BUG_ON(new->out_handle.data || new->out_token.data);
	new->out_handle.len = item->out_handle.len;
	item->out_handle.len = 0;
	new->out_token.len = item->out_token.len;
	item->out_token.len = 0;
	new->out_handle.data = item->out_handle.data;
	item->out_handle.data = NULL;
	new->out_token.data = item->out_token.data;
	item->out_token.data = NULL;

	new->major_status = item->major_status;
	new->minor_status = item->minor_status;
}

static void rsi_request(struct cache_detail *cd,
                       struct cache_head *h,
                       char **bpp, int *blen)
{
	struct rsi *rsii = container_of(h, struct rsi, h);

	qword_addhex(bpp, blen, rsii->in_handle.data, rsii->in_handle.len);
	qword_addhex(bpp, blen, rsii->in_token.data, rsii->in_token.len);
	(*bpp)[-1] = '\n';
}


static int rsi_parse(struct cache_detail *cd,
                    char *mesg, int mlen)
{
	/* context token expiry major minor context token */
	char *buf = mesg;
	char *ep;
	int len;
	struct rsi rsii, *rsip = NULL;
	time_t expiry;
	int status = -EINVAL;

	memset(&rsii, 0, sizeof(rsii));
	/* handle */
	len = qword_get(&mesg, buf, mlen);
	if (len < 0)
		goto out;
	status = -ENOMEM;
	if (dup_to_netobj(&rsii.in_handle, buf, len))
		goto out;

	/* token */
	len = qword_get(&mesg, buf, mlen);
	status = -EINVAL;
	if (len < 0)
		goto out;;
	status = -ENOMEM;
	if (dup_to_netobj(&rsii.in_token, buf, len))
		goto out;

	rsii.h.flags = 0;
	/* expiry */
	expiry = get_expiry(&mesg);
	status = -EINVAL;
	if (expiry == 0)
		goto out;

	/* major/minor */
	len = qword_get(&mesg, buf, mlen);
	if (len < 0)
		goto out;
	if (len == 0) {
		goto out;
	} else {
		rsii.major_status = simple_strtoul(buf, &ep, 10);
		if (*ep)
			goto out;
		len = qword_get(&mesg, buf, mlen);
		if (len <= 0)
			goto out;
		rsii.minor_status = simple_strtoul(buf, &ep, 10);
		if (*ep)
			goto out;

		/* out_handle */
		len = qword_get(&mesg, buf, mlen);
		if (len < 0)
			goto out;
		status = -ENOMEM;
		if (dup_to_netobj(&rsii.out_handle, buf, len))
			goto out;

		/* out_token */
		len = qword_get(&mesg, buf, mlen);
		status = -EINVAL;
		if (len < 0)
			goto out;
		status = -ENOMEM;
		if (dup_to_netobj(&rsii.out_token, buf, len))
			goto out;
	}
	rsii.h.expiry_time = expiry;
	rsip = rsi_lookup(&rsii, 1);
	status = 0;
out:
	rsi_free(&rsii);
	if (rsip)
		rsi_put(&rsip->h, &rsi_cache);
	return status;
}

static struct cache_detail rsi_cache = {
	.hash_size	= RSI_HASHMAX,
	.hash_table     = rsi_table,
	.name           = "auth.rpcsec.init",
	.cache_put      = rsi_put,
	.cache_request  = rsi_request,
	.cache_parse    = rsi_parse,
};

static DefineSimpleCacheLookup(rsi, 0)

/*
 * The rpcsec_context cache is used to store a context that is
 * used in data exchange.
 * The key is a context handle. The content is:
 *  uid, gidlist, mechanism, service-set, mech-specific-data
 */

#define	RSC_HASHBITS	10
#define	RSC_HASHMAX	(1<<RSC_HASHBITS)
#define	RSC_HASHMASK	(RSC_HASHMAX-1)

#define GSS_SEQ_WIN	128

struct gss_svc_seq_data {
	/* highest seq number seen so far: */
	int			sd_max;
	/* for i such that sd_max-GSS_SEQ_WIN < i <= sd_max, the i-th bit of
	 * sd_win is nonzero iff sequence number i has been seen already: */
	unsigned long		sd_win[GSS_SEQ_WIN/BITS_PER_LONG];
	spinlock_t		sd_lock;
};

struct rsc {
	struct cache_head	h;
	struct xdr_netobj	handle;
	struct svc_cred		cred;
	struct gss_svc_seq_data	seqdata;
	struct gss_ctx		*mechctx;
};

static struct cache_head *rsc_table[RSC_HASHMAX];
static struct cache_detail rsc_cache;
static struct rsc *rsc_lookup(struct rsc *item, int set);

static void rsc_free(struct rsc *rsci)
{
	kfree(rsci->handle.data);
	if (rsci->mechctx)
		gss_delete_sec_context(&rsci->mechctx);
	if (rsci->cred.cr_group_info)
		put_group_info(rsci->cred.cr_group_info);
}

static void rsc_put(struct cache_head *item, struct cache_detail *cd)
{
	struct rsc *rsci = container_of(item, struct rsc, h);

	if (cache_put(item, cd)) {
		rsc_free(rsci);
		kfree(rsci);
	}
}

static inline int
rsc_hash(struct rsc *rsci)
{
	return hash_mem(rsci->handle.data, rsci->handle.len, RSC_HASHBITS);
}

static inline int
rsc_match(struct rsc *new, struct rsc *tmp)
{
	return netobj_equal(&new->handle, &tmp->handle);
}

static inline void
rsc_init(struct rsc *new, struct rsc *tmp)
{
	new->handle.len = tmp->handle.len;
	tmp->handle.len = 0;
	new->handle.data = tmp->handle.data;
	tmp->handle.data = NULL;
	new->mechctx = NULL;
}

static inline void
rsc_update(struct rsc *new, struct rsc *tmp)
{
	new->mechctx = tmp->mechctx;
	tmp->mechctx = NULL;
	memset(&new->seqdata, 0, sizeof(new->seqdata));
	spin_lock_init(&new->seqdata.sd_lock);
	new->cred = tmp->cred;
	tmp->cred.cr_group_info = NULL;
}

static int rsc_parse(struct cache_detail *cd,
		     char *mesg, int mlen)
{
	/* contexthandle expiry [ uid gid N <n gids> mechname ...mechdata... ] */
	char *buf = mesg;
	int len, rv;
	struct rsc rsci, *rscp = NULL;
	time_t expiry;
	int status = -EINVAL;

	memset(&rsci, 0, sizeof(rsci));
	/* context handle */
	len = qword_get(&mesg, buf, mlen);
	if (len < 0) goto out;
	status = -ENOMEM;
	if (dup_to_netobj(&rsci.handle, buf, len))
		goto out;

	rsci.h.flags = 0;
	/* expiry */
	expiry = get_expiry(&mesg);
	status = -EINVAL;
	if (expiry == 0)
		goto out;

	/* uid, or NEGATIVE */
	rv = get_int(&mesg, &rsci.cred.cr_uid);
	if (rv == -EINVAL)
		goto out;
	if (rv == -ENOENT)
		set_bit(CACHE_NEGATIVE, &rsci.h.flags);
	else {
		int N, i;
		struct gss_api_mech *gm;
		struct xdr_netobj tmp_buf;

		/* gid */
		if (get_int(&mesg, &rsci.cred.cr_gid))
			goto out;

		/* number of additional gid's */
		if (get_int(&mesg, &N))
			goto out;
		rsci.cred.cr_group_info = groups_alloc(N);
		if (rsci.cred.cr_group_info == NULL)
			goto out;

		/* gid's */
		for (i=0; i<N; i++) {
			gid_t gid;
			if (get_int(&mesg, &gid))
				goto out;
			GROUP_AT(rsci.cred.cr_group_info, i) = gid;
		}

		/* mech name */
		len = qword_get(&mesg, buf, mlen);
		if (len < 0)
			goto out;
		gm = gss_mech_get_by_name(buf);

		/* mech-specific data: */
		len = qword_get(&mesg, buf, mlen);
		if (len < 0) {
			gss_mech_put(gm);
			goto out;
		}
		tmp_buf.len = len;
		tmp_buf.data = buf;
		if (gss_import_sec_context(&tmp_buf, gm, &rsci.mechctx)) {
			gss_mech_put(gm);
			goto out;
		}
		gss_mech_put(gm);
	}
	rsci.h.expiry_time = expiry;
	rscp = rsc_lookup(&rsci, 1);
	status = 0;
out:
	rsc_free(&rsci);
	if (rscp)
		rsc_put(&rscp->h, &rsc_cache);
	return status;
}

static struct cache_detail rsc_cache = {
	.hash_size	= RSC_HASHMAX,
	.hash_table	= rsc_table,
	.name		= "auth.rpcsec.context",
	.cache_put	= rsc_put,
	.cache_parse	= rsc_parse,
};

static DefineSimpleCacheLookup(rsc, 0);

struct rsc *
gss_svc_searchbyctx(struct xdr_netobj *handle)
{
	struct rsc rsci;
	struct rsc *found;

	rsci.handle = *handle;
	found = rsc_lookup(&rsci, 0);
	if (!found)
		return NULL;
	if (cache_check(&rsc_cache, &found->h, NULL))
		return NULL;
	return found;
}

/* Implements sequence number algorithm as specified in RFC 2203. */
static int
gss_check_seq_num(struct rsc *rsci, int seq_num)
{
	struct gss_svc_seq_data *sd = &rsci->seqdata;

	spin_lock(&sd->sd_lock);
	if (seq_num > sd->sd_max) {
		if (seq_num >= sd->sd_max + GSS_SEQ_WIN) {
			memset(sd->sd_win,0,sizeof(sd->sd_win));
			sd->sd_max = seq_num;
		} else while (sd->sd_max < seq_num) {
			sd->sd_max++;
			__clear_bit(sd->sd_max % GSS_SEQ_WIN, sd->sd_win);
		}
		__set_bit(seq_num % GSS_SEQ_WIN, sd->sd_win);
		goto ok;
	} else if (seq_num <= sd->sd_max - GSS_SEQ_WIN) {
		goto drop;
	}
	/* sd_max - GSS_SEQ_WIN < seq_num <= sd_max */
	if (__test_and_set_bit(seq_num % GSS_SEQ_WIN, sd->sd_win))
		goto drop;
ok:
	spin_unlock(&sd->sd_lock);
	return 1;
drop:
	spin_unlock(&sd->sd_lock);
	return 0;
}

static inline u32 round_up_to_quad(u32 i)
{
	return (i + 3 ) & ~3;
}

static inline int
svc_safe_getnetobj(struct iovec *argv, struct xdr_netobj *o)
{
	int l;

	if (argv->iov_len < 4)
		return -1;
	o->len = ntohl(svc_getu32(argv));
	l = round_up_to_quad(o->len);
	if (argv->iov_len < l)
		return -1;
	o->data = argv->iov_base;
	argv->iov_base += l;
	argv->iov_len -= l;
	return 0;
}

static inline int
svc_safe_putnetobj(struct iovec *resv, struct xdr_netobj *o)
{
	u32 *p;

	if (resv->iov_len + 4 > PAGE_SIZE)
		return -1;
	svc_putu32(resv, htonl(o->len));
	p = resv->iov_base + resv->iov_len;
	resv->iov_len += round_up_to_quad(o->len);
	if (resv->iov_len > PAGE_SIZE)
		return -1;
	memcpy(p, o->data, o->len);
	memset((u8 *)p + o->len, 0, round_up_to_quad(o->len) - o->len);
	return 0;
}

/* Verify the checksum on the header and return SVC_OK on success.
 * Otherwise, return SVC_DROP (in the case of a bad sequence number)
 * or return SVC_DENIED and indicate error in authp.
 */
static int
gss_verify_header(struct svc_rqst *rqstp, struct rsc *rsci,
		  u32 *rpcstart, struct rpc_gss_wire_cred *gc, u32 *authp)
{
	struct gss_ctx		*ctx_id = rsci->mechctx;
	struct xdr_buf		rpchdr;
	struct xdr_netobj	checksum;
	u32			flavor = 0;
	struct iovec		*argv = &rqstp->rq_arg.head[0];
	struct iovec		iov;

	/* data to compute the checksum over: */
	iov.iov_base = rpcstart;
	iov.iov_len = (u8 *)argv->iov_base - (u8 *)rpcstart;
	xdr_buf_from_iov(&iov, &rpchdr);

	*authp = rpc_autherr_badverf;
	if (argv->iov_len < 4)
		return SVC_DENIED;
	flavor = ntohl(svc_getu32(argv));
	if (flavor != RPC_AUTH_GSS)
		return SVC_DENIED;
	if (svc_safe_getnetobj(argv, &checksum))
		return SVC_DENIED;

	if (rqstp->rq_deferred) /* skip verification of revisited request */
		return SVC_OK;
	if (gss_verify_mic(ctx_id, &rpchdr, &checksum, NULL)
							!= GSS_S_COMPLETE) {
		*authp = rpcsec_gsserr_credproblem;
		return SVC_DENIED;
	}

	if (gc->gc_seq > MAXSEQ) {
		dprintk("svcauth_gss: discarding request with large"
			" sequence number %d\n", gc->gc_seq);
		*authp = rpcsec_gsserr_ctxproblem;
		return SVC_DENIED;
	}
	if (!gss_check_seq_num(rsci, gc->gc_seq)) {
		dprintk("svcauth_gss: discarding request with old"
				" sequence number %d\n", gc->gc_seq);
		return SVC_DROP;
	}
	return SVC_OK;
}

static int
gss_write_verf(struct svc_rqst *rqstp, struct gss_ctx *ctx_id, u32 seq)
{
	u32			xdr_seq;
	u32			maj_stat;
	struct xdr_buf		verf_data;
	struct xdr_netobj	mic;
	u32			*p;
	struct iovec		iov;

	svc_putu32(rqstp->rq_res.head, htonl(RPC_AUTH_GSS));
	xdr_seq = htonl(seq);

	iov.iov_base = &xdr_seq;
	iov.iov_len = sizeof(xdr_seq);
	xdr_buf_from_iov(&iov, &verf_data);
	p = rqstp->rq_res.head->iov_base + rqstp->rq_res.head->iov_len;
	mic.data = (u8 *)(p + 1);
	maj_stat = gss_get_mic(ctx_id, 0, &verf_data, &mic);
	if (maj_stat != GSS_S_COMPLETE)
		return -1;
	*p++ = htonl(mic.len);
	memset((u8 *)p + mic.len, 0, round_up_to_quad(mic.len) - mic.len);
	p += XDR_QUADLEN(mic.len);
	if (!xdr_ressize_check(rqstp, p))
		return -1;
	return 0;
}

struct gss_domain {
	struct auth_domain	h;
	u32			pseudoflavor;
};

/* XXX this should be done in gss_pseudoflavors, and shouldn't be hardcoded: */
static struct auth_domain *
find_gss_auth_domain(struct gss_ctx *ctx, u32 svc)
{
	switch(gss_get_pseudoflavor(ctx, 0, svc)) {
		case RPC_AUTH_GSS_KRB5:
			return auth_domain_find("gss/krb5");
		case RPC_AUTH_GSS_KRB5I:
			return auth_domain_find("gss/krb5i");
		case RPC_AUTH_GSS_KRB5P:
			return auth_domain_find("gss/krb5p");
	}
	return NULL;
}

int
svcauth_gss_register_pseudoflavor(u32 pseudoflavor, char * name)
{
	struct gss_domain	*new;
	struct auth_domain	*test;
	static char		*prefix = "gss/";
	int			stat = -1;

	new = kmalloc(sizeof(*new), GFP_KERNEL);
	if (!new)
		goto out;
	cache_init(&new->h.h);
	atomic_inc(&new->h.h.refcnt);
	new->h.name = kmalloc(strlen(name) + strlen(prefix) + 1, GFP_KERNEL);
	if (!new->h.name)
		goto out_free_dom;
	strcpy(new->h.name, prefix);
	strcat(new->h.name, name);
	new->h.flavour = RPC_AUTH_GSS;
	new->pseudoflavor = pseudoflavor;
	new->h.h.expiry_time = NEVER;
	new->h.h.flags = 0;

	test = auth_domain_lookup(&new->h, 1);
	if (test == &new->h) {
		BUG_ON(atomic_dec_and_test(&new->h.h.refcnt));
	} else { /* XXX Duplicate registration? */
		auth_domain_put(&new->h);
		goto out;
	}
	return 0;

out_free_dom:
	kfree(new);
out:
	return stat;
}

/*
 * Accept an rpcsec packet.
 * If context establishment, punt to user space
 * If data exchange, verify/decrypt
 * If context destruction, handle here
 * In the context establishment and destruction case we encode
 * response here and return SVC_COMPLETE.
 */
static int
svcauth_gss_accept(struct svc_rqst *rqstp, u32 *authp)
{
	struct iovec	*argv = &rqstp->rq_arg.head[0];
	struct iovec	*resv = &rqstp->rq_res.head[0];
	u32		crlen;
	struct xdr_netobj tmpobj;
	struct gss_svc_data *svcdata = rqstp->rq_auth_data;
	struct rpc_gss_wire_cred *gc;
	struct rsc	*rsci = NULL;
	struct rsi	*rsip, rsikey;
	u32		*rpcstart;
	u32		*reject_stat = resv->iov_base;
	int		ret;

	dprintk("RPC: svcauth_gss: argv->iov_len = %zd\n",argv->iov_len);

	*authp = rpc_autherr_badcred;
	if (!svcdata)
		svcdata = kmalloc(sizeof(*svcdata), GFP_KERNEL);
	if (!svcdata)
		goto auth_err;
	rqstp->rq_auth_data = svcdata;
	gc = &svcdata->clcred;

	/* start of rpc packet is 7 u32's back from here:
	 * xid direction rpcversion prog vers proc flavour
	 */
	rpcstart = argv->iov_base;
	rpcstart -= 7;

	/* credential is:
	 *   version(==1), proc(0,1,2,3), seq, service (1,2,3), handle
	 * at least 5 u32s, and is preceeded by length, so that makes 6.
	 */

	if (argv->iov_len < 5 * 4)
		goto auth_err;
	crlen = ntohl(svc_getu32(argv));
	if (ntohl(svc_getu32(argv)) != RPC_GSS_VERSION)
		goto auth_err;
	gc->gc_proc = ntohl(svc_getu32(argv));
	gc->gc_seq = ntohl(svc_getu32(argv));
	gc->gc_svc = ntohl(svc_getu32(argv));
	if (svc_safe_getnetobj(argv, &gc->gc_ctx))
		goto auth_err;
	if (crlen != round_up_to_quad(gc->gc_ctx.len) + 5 * 4)
		goto auth_err;

	if ((gc->gc_proc != RPC_GSS_PROC_DATA) && (rqstp->rq_proc != 0))
		goto auth_err;

	/*
	 * We've successfully parsed the credential. Let's check out the
	 * verifier.  An AUTH_NULL verifier is allowed (and required) for
	 * INIT and CONTINUE_INIT requests. AUTH_RPCSEC_GSS is required for
	 * PROC_DATA and PROC_DESTROY.
	 *
	 * AUTH_NULL verifier is 0 (AUTH_NULL), 0 (length).
	 * AUTH_RPCSEC_GSS verifier is:
	 *   6 (AUTH_RPCSEC_GSS), length, checksum.
	 * checksum is calculated over rpcheader from xid up to here.
	 */
	*authp = rpc_autherr_badverf;
	switch (gc->gc_proc) {
	case RPC_GSS_PROC_INIT:
	case RPC_GSS_PROC_CONTINUE_INIT:
		if (argv->iov_len < 2 * 4)
			goto auth_err;
		if (ntohl(svc_getu32(argv)) != RPC_AUTH_NULL)
			goto auth_err;
		if (ntohl(svc_getu32(argv)) != 0)
			goto auth_err;
		break;
	case RPC_GSS_PROC_DATA:
	case RPC_GSS_PROC_DESTROY:
		/* integrity and privacy unsupported: */
		if (gc->gc_svc != RPC_GSS_SVC_NONE)
			goto auth_err;
		*authp = rpcsec_gsserr_credproblem;
		rsci = gss_svc_searchbyctx(&gc->gc_ctx);
		if (!rsci)
			goto auth_err;
		switch (gss_verify_header(rqstp, rsci, rpcstart, gc, authp)) {
		case SVC_OK:
			break;
		case SVC_DENIED:
			goto auth_err;
		case SVC_DROP:
			goto drop;
		}
		break;
	default:
		*authp = rpc_autherr_rejectedcred;
		goto auth_err;
	}

	/* now act upon the command: */
	switch (gc->gc_proc) {
	case RPC_GSS_PROC_INIT:
	case RPC_GSS_PROC_CONTINUE_INIT:
		*authp = rpc_autherr_badcred;
		if (gc->gc_proc == RPC_GSS_PROC_INIT && gc->gc_ctx.len != 0)
			goto auth_err;
		memset(&rsikey, 0, sizeof(rsikey));
		if (dup_netobj(&rsikey.in_handle, &gc->gc_ctx))
			goto drop;
		*authp = rpc_autherr_badverf;
		if (svc_safe_getnetobj(argv, &tmpobj)) {
			kfree(rsikey.in_handle.data);
			goto auth_err;
		}
		if (dup_netobj(&rsikey.in_token, &tmpobj)) {
			kfree(rsikey.in_handle.data);
			goto drop;
		}

		rsip = rsi_lookup(&rsikey, 0);
		rsi_free(&rsikey);
		if (!rsip) {
			goto drop;
		}
		switch(cache_check(&rsi_cache, &rsip->h, &rqstp->rq_chandle)) {
		case -EAGAIN:
			goto drop;
		case -ENOENT:
			goto drop;
		case 0:
			rsci = gss_svc_searchbyctx(&rsip->out_handle);
			if (!rsci) {
				goto drop;
			}
			if (gss_write_verf(rqstp, rsci->mechctx, GSS_SEQ_WIN))
				goto drop;
			if (resv->iov_len + 4 > PAGE_SIZE)
				goto drop;
			svc_putu32(resv, rpc_success);
			if (svc_safe_putnetobj(resv, &rsip->out_handle))
				goto drop;
			if (resv->iov_len + 3 * 4 > PAGE_SIZE)
				goto drop;
			svc_putu32(resv, htonl(rsip->major_status));
			svc_putu32(resv, htonl(rsip->minor_status));
			svc_putu32(resv, htonl(GSS_SEQ_WIN));
			if (svc_safe_putnetobj(resv, &rsip->out_token))
				goto drop;
			rqstp->rq_client = NULL;
		}
		goto complete;
	case RPC_GSS_PROC_DESTROY:
		set_bit(CACHE_NEGATIVE, &rsci->h.flags);
		if (resv->iov_len + 4 > PAGE_SIZE)
			goto drop;
		svc_putu32(resv, rpc_success);
		goto complete;
	case RPC_GSS_PROC_DATA:
		rqstp->rq_client =
			find_gss_auth_domain(rsci->mechctx, gc->gc_svc);
		if (rqstp->rq_client == NULL)
			goto auth_err;
		*authp = rpcsec_gsserr_ctxproblem;
		if (gss_write_verf(rqstp, rsci->mechctx, gc->gc_seq))
			goto auth_err;
		/* For use when wrapping: */
		svcdata->body_start = resv->iov_base + 1;
		rqstp->rq_cred = rsci->cred;
		get_group_info(rsci->cred.cr_group_info);
		ret = SVC_OK;
		goto out;
	}
auth_err:
	/* Restore write pointer to original value: */
	xdr_ressize_check(rqstp, reject_stat);
	ret = SVC_DENIED;
	goto out;
complete:
	ret = SVC_COMPLETE;
	goto out;
drop:
	ret = SVC_DROP;
out:
	if (rsci)
		rsc_put(&rsci->h, &rsc_cache);
	return ret;
}

static int
svcauth_gss_release(struct svc_rqst *rqstp)
{
	if (rqstp->rq_client)
		auth_domain_put(rqstp->rq_client);
	rqstp->rq_client = NULL;
	if (rqstp->rq_cred.cr_group_info)
		put_group_info(rqstp->rq_cred.cr_group_info);
	rqstp->rq_cred.cr_group_info = NULL;

	return 0;
}

static void
svcauth_gss_domain_release(struct auth_domain *dom)
{
	struct gss_domain *gd = container_of(dom, struct gss_domain, h);

	kfree(dom->name);
	kfree(gd);
}

struct auth_ops svcauthops_gss = {
	.name		= "rpcsec_gss",
	.flavour	= RPC_AUTH_GSS,
	.accept		= svcauth_gss_accept,
	.release	= svcauth_gss_release,
	.domain_release = svcauth_gss_domain_release,
};

int
gss_svc_init(void)
{
	cache_register(&rsc_cache);
	cache_register(&rsi_cache);
	svc_auth_register(RPC_AUTH_GSS, &svcauthops_gss);
	return 0;
}
