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authorYunhong Jiang <yunhong.jiang@intel.com>2015-08-04 12:17:53 -0700
committerYunhong Jiang <yunhong.jiang@intel.com>2015-08-04 15:44:42 -0700
commit9ca8dbcc65cfc63d6f5ef3312a33184e1d726e00 (patch)
tree1c9cafbcd35f783a87880a10f85d1a060db1a563 /kernel/net/dns_resolver/dns_query.c
parent98260f3884f4a202f9ca5eabed40b1354c489b29 (diff)
Add the rt linux 4.1.3-rt3 as base
Import the rt linux 4.1.3-rt3 as OPNFV kvm base. It's from git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-4.1.y-rt and the base is: commit 0917f823c59692d751951bf5ea699a2d1e2f26a2 Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Date: Sat Jul 25 12:13:34 2015 +0200 Prepare v4.1.3-rt3 Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> We lose all the git history this way and it's not good. We should apply another opnfv project repo in future. Change-Id: I87543d81c9df70d99c5001fbdf646b202c19f423 Signed-off-by: Yunhong Jiang <yunhong.jiang@intel.com>
Diffstat (limited to 'kernel/net/dns_resolver/dns_query.c')
-rw-r--r--kernel/net/dns_resolver/dns_query.c167
1 files changed, 167 insertions, 0 deletions
diff --git a/kernel/net/dns_resolver/dns_query.c b/kernel/net/dns_resolver/dns_query.c
new file mode 100644
index 000000000..39d2c39bd
--- /dev/null
+++ b/kernel/net/dns_resolver/dns_query.c
@@ -0,0 +1,167 @@
+/* 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, time_t *_expiry)
+{
+ struct key *rkey;
+ 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 = rkey->type_data.x[0];
+ if (ret)
+ goto put;
+
+ upayload = rcu_dereference_protected(rkey->payload.data,
+ lockdep_is_held(&rkey->sem));
+ 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);