/* Upcall routine, designed to work as a key type and working through
 * /sbin/request-key to contact userspace when handling DNS queries.
 *
 * See Documentation/networking/dns_resolver.txt
 *
 *   Copyright (c) 2007 Igor Mammedov
 *   Author(s): Igor Mammedov (niallain@gmail.com)
 *              Steve French (sfrench@us.ibm.com)
 *              Wang Lei (wang840925@gmail.com)
 *		David Howells (dhowells@redhat.com)
 *
 *   The upcall wrapper used to make an arbitrary DNS query.
 *
 *   This function requires the appropriate userspace tool dns.upcall to be
 *   installed and something like the following lines should be added to the
 *   /etc/request-key.conf file:
 *
 *	create dns_resolver * * /sbin/dns.upcall %k
 *
 *   For example to use this module to query AFSDB RR:
 *
 *	create dns_resolver afsdb:* * /sbin/dns.afsdb %k
 *
 *   This library is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU Lesser General Public License as published
 *   by the Free Software Foundation; either version 2.1 of the License, or
 *   (at your option) any later version.
 *
 *   This library is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
 *   the GNU Lesser General Public License for more details.
 *
 *   You should have received a copy of the GNU Lesser General Public License
 *   along with this library; if not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/module.h>
#include <linux/slab.h>
#include <linux/dns_resolver.h>
#include <linux/err.h>
#include <keys/dns_resolver-type.h>
#include <keys/user-type.h>

#include "internal.h"

/**
 * dns_query - Query the DNS
 * @type: Query type (or NULL for straight host->IP lookup)
 * @name: Name to look up
 * @namelen: Length of name
 * @options: Request options (or NULL if no options)
 * @_result: Where to place the returned data.
 * @_expiry: Where to store the result expiry time (or NULL)
 *
 * The data will be returned in the pointer at *result, and the caller is
 * responsible for freeing it.
 *
 * The description should be of the form "[<query_type>:]<domain_name>", and
 * the options need to be appropriate for the query type requested.  If no
 * query_type is given, then the query is a straight hostname to IP address
 * lookup.
 *
 * The DNS resolution lookup is performed by upcalling to userspace by way of
 * requesting a key of type dns_resolver.
 *
 * Returns the size of the result on success, -ve error code otherwise.
 */
int dns_query(const char *type, const char *name, size_t namelen,
	      const char *options, char **_result, time64_t *_expiry)
{
	struct key *rkey;
	const struct user_key_payload *upayload;
	const struct cred *saved_cred;
	size_t typelen, desclen;
	char *desc, *cp;
	int ret, len;

	kenter("%s,%*.*s,%zu,%s",
	       type, (int)namelen, (int)namelen, name, namelen, options);

	if (!name || namelen == 0 || !_result)
		return -EINVAL;

	/* construct the query key description as "[<type>:]<name>" */
	typelen = 0;
	desclen = 0;
	if (type) {
		typelen = strlen(type);
		if (typelen < 1)
			return -EINVAL;
		desclen += typelen + 1;
	}

	if (!namelen)
		namelen = strnlen(name, 256);
	if (namelen < 3 || namelen > 255)
		return -EINVAL;
	desclen += namelen + 1;

	desc = kmalloc(desclen, GFP_KERNEL);
	if (!desc)
		return -ENOMEM;

	cp = desc;
	if (type) {
		memcpy(cp, type, typelen);
		cp += typelen;
		*cp++ = ':';
	}
	memcpy(cp, name, namelen);
	cp += namelen;
	*cp = '\0';

	if (!options)
		options = "";
	kdebug("call request_key(,%s,%s)", desc, options);

	/* make the upcall, using special credentials to prevent the use of
	 * add_key() to preinstall malicious redirections
	 */
	saved_cred = override_creds(dns_resolver_cache);
	rkey = request_key(&key_type_dns_resolver, desc, options);
	revert_creds(saved_cred);
	kfree(desc);
	if (IS_ERR(rkey)) {
		ret = PTR_ERR(rkey);
		goto out;
	}

	down_read(&rkey->sem);
	set_bit(KEY_FLAG_ROOT_CAN_INVAL, &rkey->flags);
	rkey->perm |= KEY_USR_VIEW;

	ret = key_validate(rkey);
	if (ret < 0)
		goto put;

	/* If the DNS server gave an error, return that to the caller */
	ret = PTR_ERR(rkey->payload.data[dns_key_error]);
	if (ret)
		goto put;

	upayload = user_key_payload(rkey);
	len = upayload->datalen;

	ret = -ENOMEM;
	*_result = kmalloc(len + 1, GFP_KERNEL);
	if (!*_result)
		goto put;

	memcpy(*_result, upayload->data, len);
	(*_result)[len] = '\0';

	if (_expiry)
		*_expiry = rkey->expiry;

	ret = len;
put:
	up_read(&rkey->sem);
	key_put(rkey);
out:
	kleave(" = %d", ret);
	return ret;
}
EXPORT_SYMBOL(dns_query);
/table></form></div><table summary='commit info' class='commit-info'>
<tr><th>author</th><td>Linus Walleij &lt;linus.walleij@linaro.org&gt;</td><td class='right'>2016-11-12 15:22:38 +0100</td></tr>
<tr><th>committer</th><td>Mark Brown &lt;broonie@kernel.org&gt;</td><td class='right'>2016-11-13 09:22:37 +0000</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/include/crypto/internal/kpp.h?id=295070e9aa015abb9b92cccfbb1e43954e938133'>295070e9aa015abb9b92cccfbb1e43954e938133</a> (<a href='/cgit.cgi/linux/net-next.git/patch/include/crypto/internal/kpp.h?id=295070e9aa015abb9b92cccfbb1e43954e938133'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/tree/?id=295070e9aa015abb9b92cccfbb1e43954e938133'>d0a08e7ce280bc877e22424437dbe59fa1857d9a</a> /<a href='/cgit.cgi/linux/net-next.git/tree/include/crypto/internal/kpp.h?id=295070e9aa015abb9b92cccfbb1e43954e938133'>include/crypto/internal/kpp.h</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/include/crypto/internal/kpp.h?id=1001354ca34179f3db924eb66672442a173147dc'>1001354ca34179f3db924eb66672442a173147dc</a> (<a href='/cgit.cgi/linux/net-next.git/diff/include/crypto/internal/kpp.h?id=295070e9aa015abb9b92cccfbb1e43954e938133&amp;id2=1001354ca34179f3db924eb66672442a173147dc'>diff</a>)</td></tr></table>
<div class='commit-subject'>regulator: stw481x-vmmc: fix ages old enable error</div><div class='commit-msg'>The regulator has never been properly enabled, it has been
dormant all the time. It's strange that MMC was working
at all, but it likely worked by the signals going through
the levelshifter and reaching the card anyways.

Fixes: 3615a34ea1a6 ("regulator: add STw481x VMMC driver")
Signed-off-by: Linus Walleij &lt;linus.walleij@linaro.org&gt;
Signed-off-by: Mark Brown &lt;broonie@kernel.org&gt;
Cc: stable@vger.kernel.org
</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?id=295070e9aa015abb9b92cccfbb1e43954e938133'>Diffstat</a> (limited to 'include/crypto/internal/kpp.h')</div><table summary='diffstat' class='diffstat'>