linux/fs/cifs/dns_resolve.c

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/*
* fs/cifs/dns_resolve.c
*
* Copyright (c) 2007 Igor Mammedov
* Author(s): Igor Mammedov (niallain@gmail.com)
* Steve French (sfrench@us.ibm.com)
*
* Contains the CIFS DFS upcall routines used for hostname to
* IP address translation.
*
* 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, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h percpu.h is included by sched.h and module.h and thus ends up being included when building most .c files. percpu.h includes slab.h which in turn includes gfp.h making everything defined by the two files universally available and complicating inclusion dependencies. percpu.h -> slab.h dependency is about to be removed. Prepare for this change by updating users of gfp and slab facilities include those headers directly instead of assuming availability. As this conversion needs to touch large number of source files, the following script is used as the basis of conversion. http://userweb.kernel.org/~tj/misc/slabh-sweep.py The script does the followings. * Scan files for gfp and slab usages and update includes such that only the necessary includes are there. ie. if only gfp is used, gfp.h, if slab is used, slab.h. * When the script inserts a new include, it looks at the include blocks and try to put the new include such that its order conforms to its surrounding. It's put in the include block which contains core kernel includes, in the same order that the rest are ordered - alphabetical, Christmas tree, rev-Xmas-tree or at the end if there doesn't seem to be any matching order. * If the script can't find a place to put a new include (mostly because the file doesn't have fitting include block), it prints out an error message indicating which .h file needs to be added to the file. The conversion was done in the following steps. 1. The initial automatic conversion of all .c files updated slightly over 4000 files, deleting around 700 includes and adding ~480 gfp.h and ~3000 slab.h inclusions. The script emitted errors for ~400 files. 2. Each error was manually checked. Some didn't need the inclusion, some needed manual addition while adding it to implementation .h or embedding .c file was more appropriate for others. This step added inclusions to around 150 files. 3. The script was run again and the output was compared to the edits from #2 to make sure no file was left behind. 4. Several build tests were done and a couple of problems were fixed. e.g. lib/decompress_*.c used malloc/free() wrappers around slab APIs requiring slab.h to be added manually. 5. The script was run on all .h files but without automatically editing them as sprinkling gfp.h and slab.h inclusions around .h files could easily lead to inclusion dependency hell. Most gfp.h inclusion directives were ignored as stuff from gfp.h was usually wildly available and often used in preprocessor macros. Each slab.h inclusion directive was examined and added manually as necessary. 6. percpu.h was updated not to include slab.h. 7. Build test were done on the following configurations and failures were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my distributed build env didn't work with gcov compiles) and a few more options had to be turned off depending on archs to make things build (like ipr on powerpc/64 which failed due to missing writeq). * x86 and x86_64 UP and SMP allmodconfig and a custom test config. * powerpc and powerpc64 SMP allmodconfig * sparc and sparc64 SMP allmodconfig * ia64 SMP allmodconfig * s390 SMP allmodconfig * alpha SMP allmodconfig * um on x86_64 SMP allmodconfig 8. percpu.h modifications were reverted so that it could be applied as a separate patch and serve as bisection point. Given the fact that I had only a couple of failures from tests on step 6, I'm fairly confident about the coverage of this conversion patch. If there is a breakage, it's likely to be something in one of the arch headers which should be easily discoverable easily on most builds of the specific arch. Signed-off-by: Tejun Heo <tj@kernel.org> Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
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#include <linux/slab.h>
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#include <linux/keyctl.h>
#include <linux/key-type.h>
#include <keys/user-type.h>
#include "dns_resolve.h"
#include "cifsglob.h"
#include "cifsproto.h"
#include "cifs_debug.h"
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static const struct cred *dns_resolver_cache;
/* Checks if supplied name is IP address
* returns:
* 1 - name is IP
* 0 - name is not IP
*/
static int
is_ip(char *name)
{
struct sockaddr_storage ss;
return cifs_convert_address((struct sockaddr *)&ss, name);
}
static int
dns_resolver_instantiate(struct key *key, const void *data,
size_t datalen)
{
int rc = 0;
char *ip;
ip = kmalloc(datalen + 1, GFP_KERNEL);
if (!ip)
return -ENOMEM;
memcpy(ip, data, datalen);
ip[datalen] = '\0';
/* make sure this looks like an address */
if (!is_ip(ip)) {
kfree(ip);
return -EINVAL;
}
key->type_data.x[0] = datalen;
key->payload.data = ip;
return rc;
}
static void
dns_resolver_destroy(struct key *key)
{
kfree(key->payload.data);
}
struct key_type key_type_dns_resolver = {
.name = "dns_resolver",
.def_datalen = sizeof(struct in_addr),
.describe = user_describe,
.instantiate = dns_resolver_instantiate,
.destroy = dns_resolver_destroy,
.match = user_match,
};
/* Resolves server name to ip address.
* input:
* unc - server UNC
* output:
* *ip_addr - pointer to server ip, caller responcible for freeing it.
* return 0 on success
*/
int
dns_resolve_server_name_to_ip(const char *unc, char **ip_addr)
{
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const struct cred *saved_cred;
int rc = -EAGAIN;
struct key *rkey = ERR_PTR(-EAGAIN);
char *name;
char *data = NULL;
int len;
if (!ip_addr || !unc)
return -EINVAL;
/* search for server name delimiter */
len = strlen(unc);
if (len < 3) {
cFYI(1, "%s: unc is too short: %s", __func__, unc);
return -EINVAL;
}
len -= 2;
name = memchr(unc+2, '\\', len);
if (!name) {
cFYI(1, "%s: probably server name is whole unc: %s",
__func__, unc);
} else {
len = (name - unc) - 2/* leading // */;
}
name = kmalloc(len+1, GFP_KERNEL);
if (!name) {
rc = -ENOMEM;
return rc;
}
memcpy(name, unc+2, len);
name[len] = 0;
if (is_ip(name)) {
cFYI(1, "%s: it is IP, skipping dns upcall: %s",
__func__, name);
data = name;
goto skip_upcall;
}
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saved_cred = override_creds(dns_resolver_cache);
rkey = request_key(&key_type_dns_resolver, name, "");
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revert_creds(saved_cred);
if (!IS_ERR(rkey)) {
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if (!(rkey->perm & KEY_USR_VIEW)) {
down_read(&rkey->sem);
rkey->perm |= KEY_USR_VIEW;
up_read(&rkey->sem);
}
len = rkey->type_data.x[0];
data = rkey->payload.data;
} else {
cERROR(1, "%s: unable to resolve: %s", __func__, name);
goto out;
}
skip_upcall:
if (data) {
*ip_addr = kmalloc(len + 1, GFP_KERNEL);
if (*ip_addr) {
memcpy(*ip_addr, data, len + 1);
if (!IS_ERR(rkey))
cFYI(1, "%s: resolved: %s to %s", __func__,
name,
*ip_addr
);
rc = 0;
} else {
rc = -ENOMEM;
}
if (!IS_ERR(rkey))
key_put(rkey);
}
out:
kfree(name);
return rc;
}
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int __init cifs_init_dns_resolver(void)
{
struct cred *cred;
struct key *keyring;
int ret;
printk(KERN_NOTICE "Registering the %s key type\n",
key_type_dns_resolver.name);
/* create an override credential set with a special thread keyring in
* which DNS requests are cached
*
* this is used to prevent malicious redirections from being installed
* with add_key().
*/
cred = prepare_kernel_cred(NULL);
if (!cred)
return -ENOMEM;
keyring = key_alloc(&key_type_keyring, ".dns_resolver", 0, 0, cred,
(KEY_POS_ALL & ~KEY_POS_SETATTR) |
KEY_USR_VIEW | KEY_USR_READ,
KEY_ALLOC_NOT_IN_QUOTA);
if (IS_ERR(keyring)) {
ret = PTR_ERR(keyring);
goto failed_put_cred;
}
ret = key_instantiate_and_link(keyring, NULL, 0, NULL, NULL);
if (ret < 0)
goto failed_put_key;
ret = register_key_type(&key_type_dns_resolver);
if (ret < 0)
goto failed_put_key;
/* instruct request_key() to use this special keyring as a cache for
* the results it looks up */
cred->thread_keyring = keyring;
cred->jit_keyring = KEY_REQKEY_DEFL_THREAD_KEYRING;
dns_resolver_cache = cred;
return 0;
failed_put_key:
key_put(keyring);
failed_put_cred:
put_cred(cred);
return ret;
}
void cifs_exit_dns_resolver(void)
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{
key_revoke(dns_resolver_cache->thread_keyring);
unregister_key_type(&key_type_dns_resolver);
put_cred(dns_resolver_cache);
printk(KERN_NOTICE "Unregistered %s key type\n",
key_type_dns_resolver.name);
}