/* 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);
ary='commit info' class='commit-info'>
<tr><th>author</th><td>Ard Biesheuvel &lt;ard.biesheuvel@linaro.org&gt;</td><td class='right'>2017-02-01 17:45:02 +0000</td></tr>
<tr><th>committer</th><td>Ingo Molnar &lt;mingo@kernel.org&gt;</td><td class='right'>2017-02-01 21:17:49 +0100</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/drivers/usb/host/ehci-sh.c?id=c8f325a59cfc718d13a50fbc746ed9b415c25e92'>c8f325a59cfc718d13a50fbc746ed9b415c25e92</a> (<a href='/cgit.cgi/linux/net-next.git/patch/drivers/usb/host/ehci-sh.c?id=c8f325a59cfc718d13a50fbc746ed9b415c25e92'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/tree/?id=c8f325a59cfc718d13a50fbc746ed9b415c25e92'>d53fbdac9d0781e39a13b2ac6b2bd258cf3b4140</a> /<a href='/cgit.cgi/linux/net-next.git/tree/drivers/usb/host/ehci-sh.c?id=c8f325a59cfc718d13a50fbc746ed9b415c25e92'>drivers/usb/host/ehci-sh.c</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/drivers/usb/host/ehci-sh.c?id=bf29bddf0417a4783da3b24e8c9e017ac649326f'>bf29bddf0417a4783da3b24e8c9e017ac649326f</a> (<a href='/cgit.cgi/linux/net-next.git/diff/drivers/usb/host/ehci-sh.c?id=c8f325a59cfc718d13a50fbc746ed9b415c25e92&amp;id2=bf29bddf0417a4783da3b24e8c9e017ac649326f'>diff</a>)</td></tr></table>
<div class='commit-subject'>efi/fdt: Avoid FDT manipulation after ExitBootServices()</div><div class='commit-msg'>Some AArch64 UEFI implementations disable the MMU in ExitBootServices(),
after which unaligned accesses to RAM are no longer supported.

Commit:

  abfb7b686a3e ("efi/libstub/arm*: Pass latest memory map to the kernel")

fixed an issue in the memory map handling of the stub FDT code, but
inadvertently created an issue with such firmware, by moving some
of the FDT manipulation to after the invocation of ExitBootServices().

Given that the stub's libfdt implementation uses the ordinary, accelerated
string functions, which rely on hardware handling of unaligned accesses,
manipulating the FDT with the MMU off may result in alignment faults.

So fix the situation by moving the update_fdt_memmap() call into the
callback function invoked by efi_exit_boot_services() right before it
calls the ExitBootServices() UEFI service (which is arguably a better
place for it anyway)

Note that disabling the MMU in ExitBootServices() is not compliant with
the UEFI spec, and carries great risk due to the fact that switching from
cached to uncached memory accesses halfway through compiler generated code
(i.e., involving a stack) can never be done in a way that is architecturally
safe.

Fixes: abfb7b686a3e ("efi/libstub/arm*: Pass latest memory map to the kernel")
Signed-off-by: Ard Biesheuvel &lt;ard.biesheuvel@linaro.org&gt;
Tested-by: Riku Voipio &lt;riku.voipio@linaro.org&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Cc: mark.rutland@arm.com
Cc: linux-efi@vger.kernel.org
Cc: matt@codeblueprint.co.uk
Cc: leif.lindholm@linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/1485971102-23330-2-git-send-email-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?id=c8f325a59cfc718d13a50fbc746ed9b415c25e92'>Diffstat</a> (limited to 'drivers/usb/host/ehci-sh.c')</div><table summary='diffstat' class='diffstat'>