/*
 *  linux/net/sunrpc/gss_mech_switch.c
 *
 *  Copyright (c) 2001 The Regents of the University of Michigan.
 *  All rights reserved.
 *
 *  J. Bruce Fields   <bfields@umich.edu>
 *
 *  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/types.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/oid_registry.h>
#include <linux/sunrpc/msg_prot.h>
#include <linux/sunrpc/gss_asn1.h>
#include <linux/sunrpc/auth_gss.h>
#include <linux/sunrpc/svcauth_gss.h>
#include <linux/sunrpc/gss_err.h>
#include <linux/sunrpc/sched.h>
#include <linux/sunrpc/gss_api.h>
#include <linux/sunrpc/clnt.h>

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

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

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

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

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

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

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

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

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

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

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

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

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

	spin_lock(&registered_mechs_lock);
	list_for_each_entry(pos, &registered_mechs, gm_list) {
		if (0 == strcmp(name, pos->gm_name)) {
			if (try_module_get(pos->gm_owner))
				gm = pos;
			break;
		}
	}
	spin_unlock(&registered_mechs_lock);
	return gm;

}

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

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

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

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

	spin_lock(&registered_mechs_lock);
	list_for_each_entry(pos, &registered_mechs, gm_list) {
		if (obj->len == pos->gm_oid.len) {
			if (0 == memcmp(obj->data, pos->gm_oid.data, obj->len)) {
				if (try_module_get(pos->gm_owner))
					gm = pos;
				break;
			}
		}
	}
	spin_unlock(&registered_mechs_lock);
	return gm;
}

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

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

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

	spin_lock(&registered_mechs_lock);
	list_for_each_entry(pos, &registered_mechs, gm_list) {
		if (!mech_supports_pseudoflavor(pos, pseudoflavor))
			continue;
		if (try_module_get(pos->gm_owner))
			gm = pos;
		break;
	}
	spin_unlock(&registered_mechs_lock);
	return gm;
}

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

	gm = _gss_mech_get_by_pseudoflavor(pseudoflavor);

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

/**
 * gss_mech_list_pseudoflavors - Discover registered GSS pseudoflavors
 * @array: array to fill in
 * @size: size of "array"
 *
 * Returns the number of array items filled in, or a negative errno.
 *
 * The returned array is not sorted by any policy.  Callers should not
 * rely on the order of the items in the returned array.
 */
int gss_mech_list_pseudoflavors(rpc_authflavor_t *array_ptr, int size)
{
	struct gss_api_mech *pos = NULL;
	int j, i = 0;

	spin_lock(&registered_mechs_lock);
	list_for_each_entry(pos, &registered_mechs, gm_list) {
		for (j = 0; j < pos->gm_pf_num; j++) {
			if (i >= size) {
				spin_unlock(&registered_mechs_lock);
				return -ENOMEM;
			}
			array_ptr[i++] = pos->gm_pfs[j].pseudoflavor;
		}
	}
	spin_unlock(&registered_mechs_lock);
	return i;
}

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

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

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

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

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

	gss_mech_put(gm);
	return pseudoflavor;
}

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

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

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

	gss_mech_put(gm);
	return -ENOENT;
}

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

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

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

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

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

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

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

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

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

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

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

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

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


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

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

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