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Merge git://git.kernel.org/pub/scm/linux/kernel/git/sfrench/cifs-2.6 

* git://git.kernel.org/pub/scm/linux/kernel/git/sfrench/cifs-2.6:
  [DNS RESOLVER] Minor typo correction
  DNS: Fixes for the DNS query module
  cifs: Include linux/err.h for IS_ERR and PTR_ERR
  DNS: Make AFS go to the DNS for AFSDB records for unknown cells
  DNS: Separate out CIFS DNS Resolver code
  cifs: account for new creduid=0x%x parameter in spnego upcall string
  cifs: reduce false positives with inode aliasing serverino autodisable
  CIFS: Make cifs_convert_address() take a const src pointer and a length
  cifs: show features compiled in as part of DebugData
  cifs: update README

Fix up trivial conflicts in fs/cifs/cifsfs.c due to workqueue changes
This commit is contained in:
Linus Torvalds 2010-08-07 12:54:46 -07:00
parent 3b7433b8a8 5227bbb008
commit 1fc7995d19
24 changed files with 831 additions and 255 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

146
Documentation/networking/dns_resolver.txt Normal file
View File

@ -0,0 +1,146 @@
===================
DNS Resolver Module
===================
Contents:
- Overview.
- Compilation.
- Setting up.
- Usage.
- Mechanism.
- Debugging.
========
OVERVIEW
========
The DNS resolver module provides a way for kernel services to make DNS queries
by way of requesting a key of key type dns_resolver. These queries are
upcalled to userspace through /sbin/request-key.
These routines must be supported by userspace tools dns.upcall, cifs.upcall and
request-key. It is under development and does not yet provide the full feature
set. The features it does support include:
(*) Implements the dns_resolver key_type to contact userspace.
It does not yet support the following AFS features:
(*) Dns query support for AFSDB resource record.
This code is extracted from the CIFS filesystem.
===========
COMPILATION
===========
The module should be enabled by turning on the kernel configuration options:
CONFIG_DNS_RESOLVER - tristate "DNS Resolver support"
==========
SETTING UP
==========
To set up this facility, the /etc/request-key.conf file must be altered so that
/sbin/request-key can appropriately direct the upcalls. For example, to handle
basic dname to IPv4/IPv6 address resolution, the following line should be
added:
#OP TYPE DESC CO-INFO PROGRAM ARG1 ARG2 ARG3 ...
#====== ============ ======= ======= ==========================
create dns_resolver * * /usr/sbin/cifs.upcall %k
To direct a query for query type 'foo', a line of the following should be added
before the more general line given above as the first match is the one taken.
create dns_resolver foo:* * /usr/sbin/dns.foo %k
=====
USAGE
=====
To make use of this facility, one of the following functions that are
implemented in the module can be called after doing:
#include <linux/dns_resolver.h>
(1) int dns_query(const char *type, const char *name, size_t namelen,
const char *options, char **_result, time_t *_expiry);
This is the basic access function. It looks for a cached DNS query and if
it doesn't find it, it upcalls to userspace to make a new DNS query, which
may then be cached. The key description is constructed as a string of the
form:
[<type>:]<name>
where <type> optionally specifies the particular upcall program to invoke,
and thus the type of query to do, and <name> specifies the string to be
looked up. The default query type is a straight hostname to IP address
set lookup.
The name parameter is not required to be a NUL-terminated string, and its
length should be given by the namelen argument.
The options parameter may be NULL or it may be a set of options
appropriate to the query type.
The return value is a string appropriate to the query type. For instance,
for the default query type it is just a list of comma-separated IPv4 and
IPv6 addresses. The caller must free the result.
The length of the result string is returned on success, and a negative
error code is returned otherwise. -EKEYREJECTED will be returned if the
DNS lookup failed.
If _expiry is non-NULL, the expiry time (TTL) of the result will be
returned also.
=========
MECHANISM
=========
The dnsresolver module registers a key type called "dns_resolver". Keys of
this type are used to transport and cache DNS lookup results from userspace.
When dns_query() is invoked, it calls request_key() to search the local
keyrings for a cached DNS result. If that fails to find one, it upcalls to
userspace to get a new result.
Upcalls to userspace are made through the request_key() upcall vector, and are
directed by means of configuration lines in /etc/request-key.conf that tell
/sbin/request-key what program to run to instantiate the key.
The upcall handler program is responsible for querying the DNS, processing the
result into a form suitable for passing to the keyctl_instantiate_key()
routine. This then passes the data to dns_resolver_instantiate() which strips
off and processes any options included in the data, and then attaches the
remainder of the string to the key as its payload.
The upcall handler program should set the expiry time on the key to that of the
lowest TTL of all the records it has extracted a result from. This means that
the key will be discarded and recreated when the data it holds has expired.
dns_query() returns a copy of the value attached to the key, or an error if
that is indicated instead.
See <file:Documentation/keys-request-key.txt> for further information about
request-key function.
=========
DEBUGGING
=========
Debugging messages can be turned on dynamically by writing a 1 into the
following file:
/sys/module/dnsresolver/parameters/debug

1
fs/afs/Kconfig
View File

@ -2,6 +2,7 @@ config AFS_FS
tristate "Andrew File System support (AFS) (EXPERIMENTAL)" tristate "Andrew File System support (AFS) (EXPERIMENTAL)"
depends on INET && EXPERIMENTAL depends on INET && EXPERIMENTAL
select AF_RXRPC select AF_RXRPC
select DNS_RESOLVER
help help
If you say Y here, you will get an experimental Andrew File System If you say Y here, you will get an experimental Andrew File System
driver. It currently only supports unsecured read-only AFS access. driver. It currently only supports unsecured read-only AFS access.

40
fs/afs/cell.c
View File

@ -13,6 +13,7 @@
#include <linux/slab.h> #include <linux/slab.h>
#include <linux/key.h> #include <linux/key.h>
#include <linux/ctype.h> #include <linux/ctype.h>
#include <linux/dns_resolver.h>
#include <linux/sched.h> #include <linux/sched.h>
#include <keys/rxrpc-type.h> #include <keys/rxrpc-type.h>
#include "internal.h" #include "internal.h"
@ -36,6 +37,8 @@ static struct afs_cell *afs_cell_alloc(const char *name, char *vllist)
struct key *key; struct key *key;
size_t namelen; size_t namelen;
char keyname[4 + AFS_MAXCELLNAME + 1], *cp, *dp, *next; char keyname[4 + AFS_MAXCELLNAME + 1], *cp, *dp, *next;
char *dvllist = NULL, *_vllist = NULL;
char delimiter = ':';
int ret; int ret;
_enter("%s,%s", name, vllist); _enter("%s,%s", name, vllist);
@ -43,8 +46,10 @@ static struct afs_cell *afs_cell_alloc(const char *name, char *vllist)
BUG_ON(!name); /* TODO: want to look up "this cell" in the cache */ BUG_ON(!name); /* TODO: want to look up "this cell" in the cache */
namelen = strlen(name); namelen = strlen(name);
if (namelen > AFS_MAXCELLNAME) if (namelen > AFS_MAXCELLNAME) {
_leave(" = -ENAMETOOLONG");
return ERR_PTR(-ENAMETOOLONG); return ERR_PTR(-ENAMETOOLONG);
}
/* allocate and initialise a cell record */ /* allocate and initialise a cell record */
cell = kzalloc(sizeof(struct afs_cell) + namelen + 1, GFP_KERNEL); cell = kzalloc(sizeof(struct afs_cell) + namelen + 1, GFP_KERNEL);
@ -64,15 +69,31 @@ static struct afs_cell *afs_cell_alloc(const char *name, char *vllist)
INIT_LIST_HEAD(&cell->vl_list); INIT_LIST_HEAD(&cell->vl_list);
spin_lock_init(&cell->vl_lock); spin_lock_init(&cell->vl_lock);
/* if the ip address is invalid, try dns query */
if (!vllist || strlen(vllist) < 7) {
ret = dns_query("afsdb", name, namelen, "ipv4", &dvllist, NULL);
if (ret < 0) {
_leave(" = %d", ret);
return ERR_PTR(ret);
}
_vllist = dvllist;
/* change the delimiter for user-space reply */
delimiter = ',';
} else {
_vllist = vllist;
}
/* fill in the VL server list from the rest of the string */ /* fill in the VL server list from the rest of the string */
do { do {
unsigned a, b, c, d; unsigned a, b, c, d;
next = strchr(vllist, ':'); next = strchr(_vllist, delimiter);
if (next) if (next)
*next++ = 0; *next++ = 0;
if (sscanf(vllist, "%u.%u.%u.%u", &a, &b, &c, &d) != 4) if (sscanf(_vllist, "%u.%u.%u.%u", &a, &b, &c, &d) != 4)
goto bad_address; goto bad_address;
if (a > 255 || b > 255 || c > 255 || d > 255) if (a > 255 || b > 255 || c > 255 || d > 255)
@ -81,7 +102,7 @@ static struct afs_cell *afs_cell_alloc(const char *name, char *vllist)
cell->vl_addrs[cell->vl_naddrs++].s_addr = cell->vl_addrs[cell->vl_naddrs++].s_addr =
htonl((a << 24) | (b << 16) | (c << 8) | d); htonl((a << 24) | (b << 16) | (c << 8) | d);
} while (cell->vl_naddrs < AFS_CELL_MAX_ADDRS && (vllist = next)); } while (cell->vl_naddrs < AFS_CELL_MAX_ADDRS && (_vllist = next));
/* create a key to represent an anonymous user */ /* create a key to represent an anonymous user */
memcpy(keyname, "afs@", 4); memcpy(keyname, "afs@", 4);
@ -110,6 +131,7 @@ bad_address:
ret = -EINVAL; ret = -EINVAL;
error: error:
key_put(cell->anonymous_key); key_put(cell->anonymous_key);
kfree(dvllist);
kfree(cell); kfree(cell);
_leave(" = %d", ret); _leave(" = %d", ret);
return ERR_PTR(ret); return ERR_PTR(ret);
@ -201,14 +223,12 @@ int afs_cell_init(char *rootcell)
} }
cp = strchr(rootcell, ':'); cp = strchr(rootcell, ':');
if (!cp) { if (!cp)
printk(KERN_ERR "kAFS: no VL server IP addresses specified\n"); _debug("kAFS: no VL server IP addresses specified");
_leave(" = -EINVAL"); else
return -EINVAL; *cp++ = 0;
}
/* allocate a cell record for the root cell */ /* allocate a cell record for the root cell */
*cp++ = 0;
new_root = afs_cell_create(rootcell, cp); new_root = afs_cell_create(rootcell, cp);
if (IS_ERR(new_root)) { if (IS_ERR(new_root)) {
_leave(" = %ld", PTR_ERR(new_root)); _leave(" = %ld", PTR_ERR(new_root));

17
fs/cifs/Kconfig
View File

@ -70,14 +70,14 @@ config CIFS_WEAK_PW_HASH
If unsure, say N. If unsure, say N.
config CIFS_UPCALL config CIFS_UPCALL
bool "Kerberos/SPNEGO advanced session setup" bool "Kerberos/SPNEGO advanced session setup"
depends on CIFS && KEYS depends on CIFS && KEYS
help select DNS_RESOLVER
Enables an upcall mechanism for CIFS which accesses help
userspace helper utilities to provide SPNEGO packaged (RFC 4178) Enables an upcall mechanism for CIFS which accesses userspace helper
Kerberos tickets which are needed to mount to certain secure servers utilities to provide SPNEGO packaged (RFC 4178) Kerberos tickets
(for which more secure Kerberos authentication is required). If which are needed to mount to certain secure servers (for which more
unsure, say N. secure Kerberos authentication is required). If unsure, say N.
config CIFS_XATTR config CIFS_XATTR
bool "CIFS extended attributes" bool "CIFS extended attributes"
@ -121,6 +121,7 @@ config CIFS_DEBUG2
config CIFS_DFS_UPCALL config CIFS_DFS_UPCALL
bool "DFS feature support" bool "DFS feature support"
depends on CIFS && KEYS depends on CIFS && KEYS
select DNS_RESOLVER
help help
Distributed File System (DFS) support is used to access shares Distributed File System (DFS) support is used to access shares
transparently in an enterprise name space, even if the share transparently in an enterprise name space, even if the share

5
fs/cifs/README
View File

@ -568,8 +568,9 @@ module can be displayed via modinfo.
Misc /proc/fs/cifs Flags and Debug Info Misc /proc/fs/cifs Flags and Debug Info
======================================= =======================================
Informational pseudo-files: Informational pseudo-files:
DebugData Displays information about active CIFS sessions DebugData Displays information about active CIFS sessions and
and shares, as well as the cifs.ko version. shares, features enabled as well as the cifs.ko
version.
Stats Lists summary resource usage information as well as per Stats Lists summary resource usage information as well as per
share statistics, if CONFIG_CIFS_STATS in enabled share statistics, if CONFIG_CIFS_STATS in enabled
in the kernel configuration. in the kernel configuration.

25
fs/cifs/cifs_debug.c
View File

@ -119,6 +119,31 @@ static int cifs_debug_data_proc_show(struct seq_file *m, void *v)
"Display Internal CIFS Data Structures for Debugging\n" "Display Internal CIFS Data Structures for Debugging\n"
"---------------------------------------------------\n"); "---------------------------------------------------\n");
seq_printf(m, "CIFS Version %s\n", CIFS_VERSION); seq_printf(m, "CIFS Version %s\n", CIFS_VERSION);
seq_printf(m, "Features: ");
#ifdef CONFIG_CIFS_DFS_UPCALL
seq_printf(m, "dfs");
seq_putc(m, ' ');
#endif
#ifdef CONFIG_CIFS_FSCACHE
seq_printf(m, "fscache");
seq_putc(m, ' ');
#endif
#ifdef CONFIG_CIFS_WEAK_PW_HASH
seq_printf(m, "lanman");
seq_putc(m, ' ');
#endif
#ifdef CONFIG_CIFS_POSIX
seq_printf(m, "posix");
seq_putc(m, ' ');
#endif
#ifdef CONFIG_CIFS_UPCALL
seq_printf(m, "spnego");
seq_putc(m, ' ');
#endif
#ifdef CONFIG_CIFS_XATTR
seq_printf(m, "xattr");
#endif
seq_putc(m, '\n');
seq_printf(m, "Active VFS Requests: %d\n", GlobalTotalActiveXid); seq_printf(m, "Active VFS Requests: %d\n", GlobalTotalActiveXid);
seq_printf(m, "Servers:"); seq_printf(m, "Servers:");

5
fs/cifs/cifs_dfs_ref.c
View File

@ -141,7 +141,7 @@ char *cifs_compose_mount_options(const char *sb_mountdata,
} }
rc = dns_resolve_server_name_to_ip(*devname, &srvIP); rc = dns_resolve_server_name_to_ip(*devname, &srvIP);
if (rc != 0) { if (rc < 0) {
cERROR(1, "%s: Failed to resolve server part of %s to IP: %d", cERROR(1, "%s: Failed to resolve server part of %s to IP: %d",
__func__, *devname, rc); __func__, *devname, rc);
goto compose_mount_options_err; goto compose_mount_options_err;
@ -150,8 +150,7 @@ char *cifs_compose_mount_options(const char *sb_mountdata,
* assuming that we have 'unc=' and 'ip=' in * assuming that we have 'unc=' and 'ip=' in
* the original sb_mountdata * the original sb_mountdata
*/ */
md_len = strlen(sb_mountdata) + strlen(srvIP) + md_len = strlen(sb_mountdata) + rc + strlen(ref->node_name) + 12;
strlen(ref->node_name) + 12;
mountdata = kzalloc(md_len+1, GFP_KERNEL); mountdata = kzalloc(md_len+1, GFP_KERNEL);
if (mountdata == NULL) { if (mountdata == NULL) {
rc = -ENOMEM; rc = -ENOMEM;

4
fs/cifs/cifs_spnego.c
View File

@ -84,6 +84,9 @@ struct key_type cifs_spnego_key_type = {
/* strlen of ";uid=0x" */ /* strlen of ";uid=0x" */
#define UID_KEY_LEN 7 #define UID_KEY_LEN 7
/* strlen of ";creduid=0x" */
#define CREDUID_KEY_LEN 11
/* strlen of ";user=" */ /* strlen of ";user=" */
#define USER_KEY_LEN 6 #define USER_KEY_LEN 6
@ -107,6 +110,7 @@ cifs_get_spnego_key(struct cifsSesInfo *sesInfo)
IP_KEY_LEN + INET6_ADDRSTRLEN + IP_KEY_LEN + INET6_ADDRSTRLEN +
MAX_MECH_STR_LEN + MAX_MECH_STR_LEN +
UID_KEY_LEN + (sizeof(uid_t) * 2) + UID_KEY_LEN + (sizeof(uid_t) * 2) +
CREDUID_KEY_LEN + (sizeof(uid_t) * 2) +
USER_KEY_LEN + strlen(sesInfo->userName) + USER_KEY_LEN + strlen(sesInfo->userName) +
PID_KEY_LEN + (sizeof(pid_t) * 2) + 1; PID_KEY_LEN + (sizeof(pid_t) * 2) + 1;

13
fs/cifs/cifsfs.c
View File

@ -45,7 +45,6 @@
#include "cifs_fs_sb.h" #include "cifs_fs_sb.h"
#include <linux/mm.h> #include <linux/mm.h>
#include <linux/key-type.h> #include <linux/key-type.h>
#include "dns_resolve.h"
#include "cifs_spnego.h" #include "cifs_spnego.h"
#include "fscache.h" #include "fscache.h"
#define CIFS_MAGIC_NUMBER 0xFF534D42 /* the first four bytes of SMB PDUs */ #define CIFS_MAGIC_NUMBER 0xFF534D42 /* the first four bytes of SMB PDUs */
@ -934,22 +933,13 @@ init_cifs(void)
if (rc) if (rc)
goto out_unregister_filesystem; goto out_unregister_filesystem;
#endif #endif
#ifdef CONFIG_CIFS_DFS_UPCALL
rc = cifs_init_dns_resolver();
if (rc)
goto out_unregister_key_type;
#endif
return 0; return 0;
#ifdef CONFIG_CIFS_DFS_UPCALL
out_unregister_key_type:
#endif
#ifdef CONFIG_CIFS_UPCALL #ifdef CONFIG_CIFS_UPCALL
unregister_key_type(&cifs_spnego_key_type);
out_unregister_filesystem: out_unregister_filesystem:
#endif
unregister_filesystem(&cifs_fs_type); unregister_filesystem(&cifs_fs_type);
#endif
out_destroy_request_bufs: out_destroy_request_bufs:
cifs_destroy_request_bufs(); cifs_destroy_request_bufs();
out_destroy_mids: out_destroy_mids:
@ -971,7 +961,6 @@ exit_cifs(void)
cifs_fscache_unregister(); cifs_fscache_unregister();
#ifdef CONFIG_CIFS_DFS_UPCALL #ifdef CONFIG_CIFS_DFS_UPCALL
cifs_dfs_release_automount_timer(); cifs_dfs_release_automount_timer();
cifs_exit_dns_resolver();
#endif #endif
#ifdef CONFIG_CIFS_UPCALL #ifdef CONFIG_CIFS_UPCALL
unregister_key_type(&cifs_spnego_key_type); unregister_key_type(&cifs_spnego_key_type);

4
fs/cifs/cifsproto.h
View File

@ -86,8 +86,8 @@ extern unsigned int smbCalcSize(struct smb_hdr *ptr);
extern unsigned int smbCalcSize_LE(struct smb_hdr *ptr); extern unsigned int smbCalcSize_LE(struct smb_hdr *ptr);
extern int decode_negTokenInit(unsigned char *security_blob, int length, extern int decode_negTokenInit(unsigned char *security_blob, int length,
struct TCP_Server_Info *server); struct TCP_Server_Info *server);
extern int cifs_convert_address(struct sockaddr *dst, char *src); extern int cifs_convert_address(struct sockaddr *dst, const char *src, int len);
extern int cifs_fill_sockaddr(struct sockaddr *dst, char *src, extern int cifs_fill_sockaddr(struct sockaddr *dst, const char *src, int len,
unsigned short int port); unsigned short int port);
extern int map_smb_to_linux_error(struct smb_hdr *smb, int logErr); extern int map_smb_to_linux_error(struct smb_hdr *smb, int logErr);
extern void header_assemble(struct smb_hdr *, char /* command */ , extern void header_assemble(struct smb_hdr *, char /* command */ ,

1
fs/cifs/connect.c
View File

@ -1543,6 +1543,7 @@ cifs_get_tcp_session(struct smb_vol *volume_info)
if (volume_info->UNCip && volume_info->UNC) { if (volume_info->UNCip && volume_info->UNC) {
rc = cifs_fill_sockaddr((struct sockaddr *)&addr, rc = cifs_fill_sockaddr((struct sockaddr *)&addr,
volume_info->UNCip, volume_info->UNCip,
strlen(volume_info->UNCip),
volume_info->port); volume_info->port);
if (!rc) { if (!rc) {
/* we failed translating address */ /* we failed translating address */

227
fs/cifs/dns_resolve.c
View File

@ -4,6 +4,8 @@
* Copyright (c) 2007 Igor Mammedov * Copyright (c) 2007 Igor Mammedov
* Author(s): Igor Mammedov (niallain@gmail.com) * Author(s): Igor Mammedov (niallain@gmail.com)
* Steve French (sfrench@us.ibm.com) * Steve French (sfrench@us.ibm.com)
* Wang Lei (wang840925@gmail.com)
* David Howells (dhowells@redhat.com)
* *
* Contains the CIFS DFS upcall routines used for hostname to * Contains the CIFS DFS upcall routines used for hostname to
* IP address translation. * IP address translation.
@ -24,214 +26,73 @@
*/ */
#include <linux/slab.h> #include <linux/slab.h>
#include <linux/keyctl.h> #include <linux/dns_resolver.h>
#include <linux/key-type.h>
#include <keys/user-type.h>
#include "dns_resolve.h" #include "dns_resolve.h"
#include "cifsglob.h" #include "cifsglob.h"
#include "cifsproto.h" #include "cifsproto.h"
#include "cifs_debug.h" #include "cifs_debug.h"
static const struct cred *dns_resolver_cache; /**
* dns_resolve_server_name_to_ip - Resolve UNC server name to ip address.
/* Checks if supplied name is IP address * @unc: UNC path specifying the server
* returns: * @ip_addr: Where to return the IP address.
* 1 - name is IP *
* 0 - name is not IP * The IP address will be returned in string form, and the caller is
*/ * responsible for freeing it.
static int *
is_ip(char *name) * Returns length of result on success, -ve on error.
{
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 int
dns_resolve_server_name_to_ip(const char *unc, char **ip_addr) dns_resolve_server_name_to_ip(const char *unc, char **ip_addr)
{ {
const struct cred *saved_cred; struct sockaddr_storage ss;
int rc = -EAGAIN; const char *hostname, *sep;
struct key *rkey = ERR_PTR(-EAGAIN);
char *name; char *name;
char *data = NULL; int len, rc;
int len;
if (!ip_addr || !unc) if (!ip_addr || !unc)
return -EINVAL; return -EINVAL;
/* search for server name delimiter */
len = strlen(unc); len = strlen(unc);
if (len < 3) { if (len < 3) {
cFYI(1, "%s: unc is too short: %s", __func__, unc); cFYI(1, "%s: unc is too short: %s", __func__, unc);
return -EINVAL; return -EINVAL;
} }
/* Discount leading slashes for cifs */
len -= 2; len -= 2;
name = memchr(unc+2, '\\', len); hostname = unc + 2;
if (!name) {
/* Search for server name delimiter */
sep = memchr(hostname, '\\', len);
if (sep)
len = sep - unc;
else
cFYI(1, "%s: probably server name is whole unc: %s", cFYI(1, "%s: probably server name is whole unc: %s",
__func__, unc); __func__, unc);
} else {
len = (name - unc) - 2/* leading // */;
}
name = kmalloc(len+1, GFP_KERNEL); /* Try to interpret hostname as an IPv4 or IPv6 address */
if (!name) { rc = cifs_convert_address((struct sockaddr *)&ss, hostname, len);
rc = -ENOMEM; if (rc > 0)
return rc; goto name_is_IP_address;
}
memcpy(name, unc+2, len);
name[len] = 0;
if (is_ip(name)) { /* Perform the upcall */
cFYI(1, "%s: it is IP, skipping dns upcall: %s", rc = dns_query(NULL, hostname, len, NULL, ip_addr, NULL);
__func__, name); if (rc < 0)
data = name; cERROR(1, "%s: unable to resolve: %*.*s",
goto skip_upcall; __func__, len, len, hostname);
} else
cFYI(1, "%s: resolved: %*.*s to %s",
saved_cred = override_creds(dns_resolver_cache); __func__, len, len, hostname, *ip_addr);
rkey = request_key(&key_type_dns_resolver, name, "");
revert_creds(saved_cred);
if (!IS_ERR(rkey)) {
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; return rc;
}
int __init cifs_init_dns_resolver(void) name_is_IP_address:
{ name = kmalloc(len + 1, GFP_KERNEL);
struct cred *cred; if (!name)
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; return -ENOMEM;
memcpy(name, hostname, len);
keyring = key_alloc(&key_type_keyring, ".dns_resolver", 0, 0, cred, name[len] = 0;
(KEY_POS_ALL & ~KEY_POS_SETATTR) | cFYI(1, "%s: unc is IP, skipping dns upcall: %s", __func__, name);
KEY_USR_VIEW | KEY_USR_READ, *ip_addr = name;
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; return 0;
failed_put_key:
key_put(keyring);
failed_put_cred:
put_cred(cred);
return ret;
}
void cifs_exit_dns_resolver(void)
{
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);
} }

2
fs/cifs/dns_resolve.h
View File

@ -24,8 +24,6 @@
#define _DNS_RESOLVE_H #define _DNS_RESOLVE_H
#ifdef __KERNEL__ #ifdef __KERNEL__
extern int __init cifs_init_dns_resolver(void);
extern void cifs_exit_dns_resolver(void);
extern int dns_resolve_server_name_to_ip(const char *unc, char **ip_addr); extern int dns_resolve_server_name_to_ip(const char *unc, char **ip_addr);
#endif /* KERNEL */ #endif /* KERNEL */

43
fs/cifs/inode.c
View File

@ -732,15 +732,9 @@ cifs_find_inode(struct inode *inode, void *opaque)
if ((inode->i_mode & S_IFMT) != (fattr->cf_mode & S_IFMT)) if ((inode->i_mode & S_IFMT) != (fattr->cf_mode & S_IFMT))
return 0; return 0;
/* /* if it's not a directory or has no dentries, then flag it */
* uh oh -- it's a directory. We can't use it since hardlinked dirs are if (S_ISDIR(inode->i_mode) && !list_empty(&inode->i_dentry))
* verboten. Disable serverino and return it as if it were found, the
* caller can discard it, generate a uniqueid and retry the find
*/
if (S_ISDIR(inode->i_mode) && !list_empty(&inode->i_dentry)) {
fattr->cf_flags |= CIFS_FATTR_INO_COLLISION; fattr->cf_flags |= CIFS_FATTR_INO_COLLISION;
cifs_autodisable_serverino(CIFS_SB(inode->i_sb));
}
return 1; return 1;
} }
@ -754,6 +748,27 @@ cifs_init_inode(struct inode *inode, void *opaque)
return 0; return 0;
} }
/*
* walk dentry list for an inode and report whether it has aliases that
* are hashed. We use this to determine if a directory inode can actually
* be used.
*/
static bool
inode_has_hashed_dentries(struct inode *inode)
{
struct dentry *dentry;
spin_lock(&dcache_lock);
list_for_each_entry(dentry, &inode->i_dentry, d_alias) {
if (!d_unhashed(dentry) || IS_ROOT(dentry)) {
spin_unlock(&dcache_lock);
return true;
}
}
spin_unlock(&dcache_lock);
return false;
}
/* Given fattrs, get a corresponding inode */ /* Given fattrs, get a corresponding inode */
struct inode * struct inode *
cifs_iget(struct super_block *sb, struct cifs_fattr *fattr) cifs_iget(struct super_block *sb, struct cifs_fattr *fattr)
@ -769,12 +784,16 @@ retry_iget5_locked:
inode = iget5_locked(sb, hash, cifs_find_inode, cifs_init_inode, fattr); inode = iget5_locked(sb, hash, cifs_find_inode, cifs_init_inode, fattr);
if (inode) { if (inode) {
/* was there a problematic inode number collision? */ /* was there a potentially problematic inode collision? */
if (fattr->cf_flags & CIFS_FATTR_INO_COLLISION) { if (fattr->cf_flags & CIFS_FATTR_INO_COLLISION) {
iput(inode);
fattr->cf_uniqueid = iunique(sb, ROOT_I);
fattr->cf_flags &= ~CIFS_FATTR_INO_COLLISION; fattr->cf_flags &= ~CIFS_FATTR_INO_COLLISION;
goto retry_iget5_locked;
if (inode_has_hashed_dentries(inode)) {
cifs_autodisable_serverino(CIFS_SB(sb));
iput(inode);
fattr->cf_uniqueid = iunique(sb, ROOT_I);
goto retry_iget5_locked;
}
} }
cifs_fattr_to_inode(inode, fattr); cifs_fattr_to_inode(inode, fattr);

45
fs/cifs/netmisc.c
View File

@ -140,17 +140,18 @@ static const struct smb_to_posix_error mapping_table_ERRHRD[] = {
* Returns 0 on failure. * Returns 0 on failure.
*/ */
static int static int
cifs_inet_pton(const int address_family, const char *cp, void *dst) cifs_inet_pton(const int address_family, const char *cp, int len, void *dst)
{ {
int ret = 0; int ret = 0;
/* calculate length by finding first slash or NULL */ /* calculate length by finding first slash or NULL */
if (address_family == AF_INET) if (address_family == AF_INET)
ret = in4_pton(cp, -1 /* len */, dst, '\\', NULL); ret = in4_pton(cp, len, dst, '\\', NULL);
else if (address_family == AF_INET6) else if (address_family == AF_INET6)
ret = in6_pton(cp, -1 /* len */, dst , '\\', NULL); ret = in6_pton(cp, len, dst , '\\', NULL);
cFYI(DBG2, "address conversion returned %d for %s", ret, cp); cFYI(DBG2, "address conversion returned %d for %*.*s",
ret, len, len, cp);
if (ret > 0) if (ret > 0)
ret = 1; ret = 1;
return ret; return ret;
@ -165,37 +166,39 @@ cifs_inet_pton(const int address_family, const char *cp, void *dst)
* Returns 0 on failure. * Returns 0 on failure.
*/ */
int int
cifs_convert_address(struct sockaddr *dst, char *src) cifs_convert_address(struct sockaddr *dst, const char *src, int len)
{ {
int rc; int rc, alen, slen;
char *pct, *endp; const char *pct;
char *endp, scope_id[13];
struct sockaddr_in *s4 = (struct sockaddr_in *) dst; struct sockaddr_in *s4 = (struct sockaddr_in *) dst;
struct sockaddr_in6 *s6 = (struct sockaddr_in6 *) dst; struct sockaddr_in6 *s6 = (struct sockaddr_in6 *) dst;
/* IPv4 address */ /* IPv4 address */
if (cifs_inet_pton(AF_INET, src, &s4->sin_addr.s_addr)) { if (cifs_inet_pton(AF_INET, src, len, &s4->sin_addr.s_addr)) {
s4->sin_family = AF_INET; s4->sin_family = AF_INET;
return 1; return 1;
} }
/* temporarily terminate string */ /* attempt to exclude the scope ID from the address part */
pct = strchr(src, '%'); pct = memchr(src, '%', len);
if (pct) alen = pct ? pct - src : len;
*pct = '\0';
rc = cifs_inet_pton(AF_INET6, src, &s6->sin6_addr.s6_addr);
/* repair temp termination (if any) and make pct point to scopeid */
if (pct)
*pct++ = '%';
rc = cifs_inet_pton(AF_INET6, src, alen, &s6->sin6_addr.s6_addr);
if (!rc) if (!rc)
return rc; return rc;
s6->sin6_family = AF_INET6; s6->sin6_family = AF_INET6;
if (pct) { if (pct) {
/* grab the scope ID */
slen = len - (alen + 1);
if (slen <= 0 || slen > 12)
return 0;
memcpy(scope_id, pct + 1, slen);
scope_id[slen] = '\0';
s6->sin6_scope_id = (u32) simple_strtoul(pct, &endp, 0); s6->sin6_scope_id = (u32) simple_strtoul(pct, &endp, 0);
if (!*pct || *endp) if (endp != scope_id + slen)
return 0; return 0;
} }
@ -203,10 +206,10 @@ cifs_convert_address(struct sockaddr *dst, char *src)
} }
int int
cifs_fill_sockaddr(struct sockaddr *dst, char *src, cifs_fill_sockaddr(struct sockaddr *dst, const char *src, int len,
const unsigned short int port) const unsigned short int port)
{ {
if (!cifs_convert_address(dst, src)) if (!cifs_convert_address(dst, src, len))
return 0; return 0;
switch (dst->sa_family) { switch (dst->sa_family) {

23
include/keys/dns_resolver-type.h Normal file
View File

@ -0,0 +1,23 @@
/* DNS resolver key type
*
* Copyright (C) 2010 Wang Lei. All Rights Reserved.
* Written by Wang Lei (wang840925@gmail.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#ifndef _KEYS_DNS_RESOLVER_TYPE_H
#define _KEYS_DNS_RESOLVER_TYPE_H
#include <linux/key-type.h>
extern struct key_type key_type_dns_resolver;
extern int request_dns_resolver_key(const char *description,
const char *callout_info,
char **data);
#endif /* _KEYS_DNS_RESOLVER_TYPE_H */

34
include/linux/dns_resolver.h Normal file
View File

@ -0,0 +1,34 @@
/*
* DNS Resolver upcall management for CIFS DFS and AFS
* Handles host name to IP address resolution and DNS query for AFSDB RR.
*
* Copyright (c) International Business Machines Corp., 2008
* Author(s): Steve French (sfrench@us.ibm.com)
* Wang Lei (wang840925@gmail.com)
*
* 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
*/
#ifndef _LINUX_DNS_RESOLVER_H
#define _LINUX_DNS_RESOLVER_H
#ifdef __KERNEL__
extern int dns_query(const char *type, const char *name, size_t namelen,
const char *options, char **_result, time_t *_expiry);
#endif /* KERNEL */
#endif /* _LINUX_DNS_RESOLVER_H */

1
net/Kconfig
View File

@ -213,6 +213,7 @@ source "net/phonet/Kconfig"
source "net/ieee802154/Kconfig" source "net/ieee802154/Kconfig"
source "net/sched/Kconfig" source "net/sched/Kconfig"
source "net/dcb/Kconfig" source "net/dcb/Kconfig"
source "net/dns_resolver/Kconfig"
config RPS config RPS
boolean boolean

1
net/Makefile
View File

@ -67,3 +67,4 @@ ifeq ($(CONFIG_NET),y)
obj-$(CONFIG_SYSCTL) += sysctl_net.o obj-$(CONFIG_SYSCTL) += sysctl_net.o
endif endif
obj-$(CONFIG_WIMAX) += wimax/ obj-$(CONFIG_WIMAX) += wimax/
obj-$(CONFIG_DNS_RESOLVER) += dns_resolver/

27
net/dns_resolver/Kconfig Normal file
View File

@ -0,0 +1,27 @@
#
# Configuration for DNS Resolver
#
config DNS_RESOLVER
tristate "DNS Resolver support"
depends on NET && KEYS
help
Saying Y here will include support for the DNS Resolver key type
which can be used to make upcalls to perform DNS lookups in
userspace.
DNS Resolver is used to query DNS server for information. Examples
being resolving a UNC hostname element to an IP address for CIFS or
performing a DNS query for AFSDB records so that AFS can locate a
cell's volume location database servers.
DNS Resolver is used by the CIFS and AFS modules, and would support
SMB2 later. DNS Resolver is supported by the userspace upcall
helper "/sbin/dns.resolver" via /etc/request-key.conf.
See <file:Documentation/networking/dns_resolver.txt> for further
information.
To compile this as a module, choose M here: the module will be called
dnsresolver.
If unsure, say N.

7
net/dns_resolver/Makefile Normal file
View File

@ -0,0 +1,7 @@
#
# Makefile for the Linux DNS Resolver.
#
obj-$(CONFIG_DNS_RESOLVER) += dns_resolver.o
dns_resolver-objs := dns_key.o dns_query.o

211
net/dns_resolver/dns_key.c Normal file
View File

@ -0,0 +1,211 @@
/* Key type used to cache DNS lookups made by the kernel
*
* 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)
*
* 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 <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/keyctl.h>
#include <linux/err.h>
#include <keys/dns_resolver-type.h>
#include <keys/user-type.h>
#include "internal.h"
MODULE_DESCRIPTION("DNS Resolver");
MODULE_AUTHOR("Wang Lei");
MODULE_LICENSE("GPL");
unsigned dns_resolver_debug;
module_param_named(debug, dns_resolver_debug, uint, S_IWUSR | S_IRUGO);
MODULE_PARM_DESC(debug, "DNS Resolver debugging mask");
const struct cred *dns_resolver_cache;
/*
* Instantiate a user defined key for dns_resolver.
*
* The data must be a NUL-terminated string, with the NUL char accounted in
* datalen.
*
* If the data contains a '#' characters, then we take the clause after each
* one to be an option of the form 'key=value'. The actual data of interest is
* the string leading up to the first '#'. For instance:
*
* "ip1,ip2,...#foo=bar"
*/
static int
dns_resolver_instantiate(struct key *key, const void *_data, size_t datalen)
{
struct user_key_payload *upayload;
int ret;
size_t result_len = 0;
const char *data = _data, *opt;
kenter("%%%d,%s,'%s',%zu",
key->serial, key->description, data, datalen);
if (datalen <= 1 || !data || data[datalen - 1] != '\0')
return -EINVAL;
datalen--;
/* deal with any options embedded in the data */
opt = memchr(data, '#', datalen);
if (!opt) {
kdebug("no options currently supported");
return -EINVAL;
}
result_len = datalen;
ret = key_payload_reserve(key, result_len);
if (ret < 0)
return -EINVAL;
upayload = kmalloc(sizeof(*upayload) + result_len + 1, GFP_KERNEL);
if (!upayload) {
kleave(" = -ENOMEM");
return -ENOMEM;
}
upayload->datalen = result_len;
memcpy(upayload->data, data, result_len);
upayload->data[result_len] = '\0';
rcu_assign_pointer(key->payload.data, upayload);
kleave(" = 0");
return 0;
}
/*
* The description is of the form "[<type>:]<domain_name>"
*
* The domain name may be a simple name or an absolute domain name (which
* should end with a period). The domain name is case-independent.
*/
static int
dns_resolver_match(const struct key *key, const void *description)
{
int slen, dlen, ret = 0;
const char *src = key->description, *dsp = description;
kenter("%s,%s", src, dsp);
if (!src || !dsp)
goto no_match;
if (strcasecmp(src, dsp) == 0)
goto matched;
slen = strlen(src);
dlen = strlen(dsp);
if (slen <= 0 || dlen <= 0)
goto no_match;
if (src[slen - 1] == '.')
slen--;
if (dsp[dlen - 1] == '.')
dlen--;
if (slen != dlen || strncasecmp(src, dsp, slen) != 0)
goto no_match;
matched:
ret = 1;
no_match:
kleave(" = %d", ret);
return ret;
}
struct key_type key_type_dns_resolver = {
.name = "dns_resolver",
.instantiate = dns_resolver_instantiate,
.match = dns_resolver_match,
.revoke = user_revoke,
.destroy = user_destroy,
.describe = user_describe,
.read = user_read,
};
static int __init 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;
kdebug("DNS resolver keyring: %d\n", key_serial(keyring));
return 0;
failed_put_key:
key_put(keyring);
failed_put_cred:
put_cred(cred);
return ret;
}
static void __exit exit_dns_resolver(void)
{
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);
}
module_init(init_dns_resolver)
module_exit(exit_dns_resolver)
MODULE_LICENSE("GPL");

160
net/dns_resolver/dns_query.c Normal file
View File

@ -0,0 +1,160 @@
/* 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, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#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 = strlen(name);
if (namelen < 3)
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);
rkey->perm |= KEY_USR_VIEW;
ret = key_validate(rkey);
if (ret < 0)
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 + 1);
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);

44
net/dns_resolver/internal.h Normal file
View File

@ -0,0 +1,44 @@
/*
* Copyright (c) 2010 Wang Lei
* Author(s): Wang Lei (wang840925@gmail.com). All Rights Reserved.
*
* Internal DNS Rsolver stuff
*
* 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 <linux/compiler.h>
#include <linux/kernel.h>
#include <linux/sched.h>
/*
* dns_key.c
*/
extern const struct cred *dns_resolver_cache;
/*
* debug tracing
*/
extern unsigned dns_resolver_debug;
#define kdebug(FMT, ...) \
do { \
if (unlikely(dns_resolver_debug)) \
printk(KERN_DEBUG "[%-6.6s] "FMT"\n", \
current->comm, ##__VA_ARGS__); \
} while (0)
#define kenter(FMT, ...) kdebug("==> %s("FMT")", __func__, ##__VA_ARGS__)
#define kleave(FMT, ...) kdebug("<== %s()"FMT"", __func__, ##__VA_ARGS__)