linux/fs/nfs/dns_resolve.c
Bryan Schumaker 89d77c8fa8 NFS: Convert v4 into a module
This patch exports symbols needed by the v4 module.  In addition, I also
switch over to using IS_ENABLED() to check if CONFIG_NFS_V4 or
CONFIG_NFS_V4_MODULE are set.

The module (nfs4.ko) will be created in the same directory as nfs.ko and
will be automatically loaded the first time you try to mount over NFS v4.

Signed-off-by: Bryan Schumaker <bjschuma@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-07-30 19:06:52 -04:00

453 lines
9.6 KiB
C

/*
* linux/fs/nfs/dns_resolve.c
*
* Copyright (c) 2009 Trond Myklebust <Trond.Myklebust@netapp.com>
*
* Resolves DNS hostnames into valid ip addresses
*/
#ifdef CONFIG_NFS_USE_KERNEL_DNS
#include <linux/module.h>
#include <linux/sunrpc/clnt.h>
#include <linux/dns_resolver.h>
#include "dns_resolve.h"
ssize_t nfs_dns_resolve_name(struct net *net, char *name, size_t namelen,
struct sockaddr *sa, size_t salen)
{
ssize_t ret;
char *ip_addr = NULL;
int ip_len;
ip_len = dns_query(NULL, name, namelen, NULL, &ip_addr, NULL);
if (ip_len > 0)
ret = rpc_pton(net, ip_addr, ip_len, sa, salen);
else
ret = -ESRCH;
kfree(ip_addr);
return ret;
}
EXPORT_SYMBOL_GPL(nfs_dns_resolve_name);
#else
#include <linux/module.h>
#include <linux/hash.h>
#include <linux/string.h>
#include <linux/kmod.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/socket.h>
#include <linux/seq_file.h>
#include <linux/inet.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/cache.h>
#include <linux/sunrpc/svcauth.h>
#include <linux/sunrpc/rpc_pipe_fs.h>
#include "dns_resolve.h"
#include "cache_lib.h"
#include "netns.h"
#define NFS_DNS_HASHBITS 4
#define NFS_DNS_HASHTBL_SIZE (1 << NFS_DNS_HASHBITS)
struct nfs_dns_ent {
struct cache_head h;
char *hostname;
size_t namelen;
struct sockaddr_storage addr;
size_t addrlen;
};
static void nfs_dns_ent_update(struct cache_head *cnew,
struct cache_head *ckey)
{
struct nfs_dns_ent *new;
struct nfs_dns_ent *key;
new = container_of(cnew, struct nfs_dns_ent, h);
key = container_of(ckey, struct nfs_dns_ent, h);
memcpy(&new->addr, &key->addr, key->addrlen);
new->addrlen = key->addrlen;
}
static void nfs_dns_ent_init(struct cache_head *cnew,
struct cache_head *ckey)
{
struct nfs_dns_ent *new;
struct nfs_dns_ent *key;
new = container_of(cnew, struct nfs_dns_ent, h);
key = container_of(ckey, struct nfs_dns_ent, h);
kfree(new->hostname);
new->hostname = kstrndup(key->hostname, key->namelen, GFP_KERNEL);
if (new->hostname) {
new->namelen = key->namelen;
nfs_dns_ent_update(cnew, ckey);
} else {
new->namelen = 0;
new->addrlen = 0;
}
}
static void nfs_dns_ent_put(struct kref *ref)
{
struct nfs_dns_ent *item;
item = container_of(ref, struct nfs_dns_ent, h.ref);
kfree(item->hostname);
kfree(item);
}
static struct cache_head *nfs_dns_ent_alloc(void)
{
struct nfs_dns_ent *item = kmalloc(sizeof(*item), GFP_KERNEL);
if (item != NULL) {
item->hostname = NULL;
item->namelen = 0;
item->addrlen = 0;
return &item->h;
}
return NULL;
};
static unsigned int nfs_dns_hash(const struct nfs_dns_ent *key)
{
return hash_str(key->hostname, NFS_DNS_HASHBITS);
}
static void nfs_dns_request(struct cache_detail *cd,
struct cache_head *ch,
char **bpp, int *blen)
{
struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h);
qword_add(bpp, blen, key->hostname);
(*bpp)[-1] = '\n';
}
static int nfs_dns_upcall(struct cache_detail *cd,
struct cache_head *ch)
{
struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h);
int ret;
ret = nfs_cache_upcall(cd, key->hostname);
if (ret)
ret = sunrpc_cache_pipe_upcall(cd, ch, nfs_dns_request);
return ret;
}
static int nfs_dns_match(struct cache_head *ca,
struct cache_head *cb)
{
struct nfs_dns_ent *a;
struct nfs_dns_ent *b;
a = container_of(ca, struct nfs_dns_ent, h);
b = container_of(cb, struct nfs_dns_ent, h);
if (a->namelen == 0 || a->namelen != b->namelen)
return 0;
return memcmp(a->hostname, b->hostname, a->namelen) == 0;
}
static int nfs_dns_show(struct seq_file *m, struct cache_detail *cd,
struct cache_head *h)
{
struct nfs_dns_ent *item;
long ttl;
if (h == NULL) {
seq_puts(m, "# ip address hostname ttl\n");
return 0;
}
item = container_of(h, struct nfs_dns_ent, h);
ttl = item->h.expiry_time - seconds_since_boot();
if (ttl < 0)
ttl = 0;
if (!test_bit(CACHE_NEGATIVE, &h->flags)) {
char buf[INET6_ADDRSTRLEN+IPV6_SCOPE_ID_LEN+1];
rpc_ntop((struct sockaddr *)&item->addr, buf, sizeof(buf));
seq_printf(m, "%15s ", buf);
} else
seq_puts(m, "<none> ");
seq_printf(m, "%15s %ld\n", item->hostname, ttl);
return 0;
}
static struct nfs_dns_ent *nfs_dns_lookup(struct cache_detail *cd,
struct nfs_dns_ent *key)
{
struct cache_head *ch;
ch = sunrpc_cache_lookup(cd,
&key->h,
nfs_dns_hash(key));
if (!ch)
return NULL;
return container_of(ch, struct nfs_dns_ent, h);
}
static struct nfs_dns_ent *nfs_dns_update(struct cache_detail *cd,
struct nfs_dns_ent *new,
struct nfs_dns_ent *key)
{
struct cache_head *ch;
ch = sunrpc_cache_update(cd,
&new->h, &key->h,
nfs_dns_hash(key));
if (!ch)
return NULL;
return container_of(ch, struct nfs_dns_ent, h);
}
static int nfs_dns_parse(struct cache_detail *cd, char *buf, int buflen)
{
char buf1[NFS_DNS_HOSTNAME_MAXLEN+1];
struct nfs_dns_ent key, *item;
unsigned long ttl;
ssize_t len;
int ret = -EINVAL;
if (buf[buflen-1] != '\n')
goto out;
buf[buflen-1] = '\0';
len = qword_get(&buf, buf1, sizeof(buf1));
if (len <= 0)
goto out;
key.addrlen = rpc_pton(cd->net, buf1, len,
(struct sockaddr *)&key.addr,
sizeof(key.addr));
len = qword_get(&buf, buf1, sizeof(buf1));
if (len <= 0)
goto out;
key.hostname = buf1;
key.namelen = len;
memset(&key.h, 0, sizeof(key.h));
ttl = get_expiry(&buf);
if (ttl == 0)
goto out;
key.h.expiry_time = ttl + seconds_since_boot();
ret = -ENOMEM;
item = nfs_dns_lookup(cd, &key);
if (item == NULL)
goto out;
if (key.addrlen == 0)
set_bit(CACHE_NEGATIVE, &key.h.flags);
item = nfs_dns_update(cd, &key, item);
if (item == NULL)
goto out;
ret = 0;
cache_put(&item->h, cd);
out:
return ret;
}
static int do_cache_lookup(struct cache_detail *cd,
struct nfs_dns_ent *key,
struct nfs_dns_ent **item,
struct nfs_cache_defer_req *dreq)
{
int ret = -ENOMEM;
*item = nfs_dns_lookup(cd, key);
if (*item) {
ret = cache_check(cd, &(*item)->h, &dreq->req);
if (ret)
*item = NULL;
}
return ret;
}
static int do_cache_lookup_nowait(struct cache_detail *cd,
struct nfs_dns_ent *key,
struct nfs_dns_ent **item)
{
int ret = -ENOMEM;
*item = nfs_dns_lookup(cd, key);
if (!*item)
goto out_err;
ret = -ETIMEDOUT;
if (!test_bit(CACHE_VALID, &(*item)->h.flags)
|| (*item)->h.expiry_time < seconds_since_boot()
|| cd->flush_time > (*item)->h.last_refresh)
goto out_put;
ret = -ENOENT;
if (test_bit(CACHE_NEGATIVE, &(*item)->h.flags))
goto out_put;
return 0;
out_put:
cache_put(&(*item)->h, cd);
out_err:
*item = NULL;
return ret;
}
static int do_cache_lookup_wait(struct cache_detail *cd,
struct nfs_dns_ent *key,
struct nfs_dns_ent **item)
{
struct nfs_cache_defer_req *dreq;
int ret = -ENOMEM;
dreq = nfs_cache_defer_req_alloc();
if (!dreq)
goto out;
ret = do_cache_lookup(cd, key, item, dreq);
if (ret == -EAGAIN) {
ret = nfs_cache_wait_for_upcall(dreq);
if (!ret)
ret = do_cache_lookup_nowait(cd, key, item);
}
nfs_cache_defer_req_put(dreq);
out:
return ret;
}
ssize_t nfs_dns_resolve_name(struct net *net, char *name,
size_t namelen, struct sockaddr *sa, size_t salen)
{
struct nfs_dns_ent key = {
.hostname = name,
.namelen = namelen,
};
struct nfs_dns_ent *item = NULL;
ssize_t ret;
struct nfs_net *nn = net_generic(net, nfs_net_id);
ret = do_cache_lookup_wait(nn->nfs_dns_resolve, &key, &item);
if (ret == 0) {
if (salen >= item->addrlen) {
memcpy(sa, &item->addr, item->addrlen);
ret = item->addrlen;
} else
ret = -EOVERFLOW;
cache_put(&item->h, nn->nfs_dns_resolve);
} else if (ret == -ENOENT)
ret = -ESRCH;
return ret;
}
EXPORT_SYMBOL_GPL(nfs_dns_resolve_name);
int nfs_dns_resolver_cache_init(struct net *net)
{
int err = -ENOMEM;
struct nfs_net *nn = net_generic(net, nfs_net_id);
struct cache_detail *cd;
struct cache_head **tbl;
cd = kzalloc(sizeof(struct cache_detail), GFP_KERNEL);
if (cd == NULL)
goto err_cd;
tbl = kzalloc(NFS_DNS_HASHTBL_SIZE * sizeof(struct cache_head *),
GFP_KERNEL);
if (tbl == NULL)
goto err_tbl;
cd->owner = THIS_MODULE,
cd->hash_size = NFS_DNS_HASHTBL_SIZE,
cd->hash_table = tbl,
cd->name = "dns_resolve",
cd->cache_put = nfs_dns_ent_put,
cd->cache_upcall = nfs_dns_upcall,
cd->cache_parse = nfs_dns_parse,
cd->cache_show = nfs_dns_show,
cd->match = nfs_dns_match,
cd->init = nfs_dns_ent_init,
cd->update = nfs_dns_ent_update,
cd->alloc = nfs_dns_ent_alloc,
nfs_cache_init(cd);
err = nfs_cache_register_net(net, cd);
if (err)
goto err_reg;
nn->nfs_dns_resolve = cd;
return 0;
err_reg:
nfs_cache_destroy(cd);
kfree(cd->hash_table);
err_tbl:
kfree(cd);
err_cd:
return err;
}
void nfs_dns_resolver_cache_destroy(struct net *net)
{
struct nfs_net *nn = net_generic(net, nfs_net_id);
struct cache_detail *cd = nn->nfs_dns_resolve;
nfs_cache_unregister_net(net, cd);
nfs_cache_destroy(cd);
kfree(cd->hash_table);
kfree(cd);
}
static int rpc_pipefs_event(struct notifier_block *nb, unsigned long event,
void *ptr)
{
struct super_block *sb = ptr;
struct net *net = sb->s_fs_info;
struct nfs_net *nn = net_generic(net, nfs_net_id);
struct cache_detail *cd = nn->nfs_dns_resolve;
int ret = 0;
if (cd == NULL)
return 0;
if (!try_module_get(THIS_MODULE))
return 0;
switch (event) {
case RPC_PIPEFS_MOUNT:
ret = nfs_cache_register_sb(sb, cd);
break;
case RPC_PIPEFS_UMOUNT:
nfs_cache_unregister_sb(sb, cd);
break;
default:
ret = -ENOTSUPP;
break;
}
module_put(THIS_MODULE);
return ret;
}
static struct notifier_block nfs_dns_resolver_block = {
.notifier_call = rpc_pipefs_event,
};
int nfs_dns_resolver_init(void)
{
return rpc_pipefs_notifier_register(&nfs_dns_resolver_block);
}
void nfs_dns_resolver_destroy(void)
{
rpc_pipefs_notifier_unregister(&nfs_dns_resolver_block);
}
#endif