linux-stable/fs/nfs/dns_resolve.c
NeilBrown c5b29f885a sunrpc: use seconds since boot in expiry cache
This protects us from confusion when the wallclock time changes.

We convert to and from wallclock when  setting or reading expiry
times.

Also use seconds since boot for last_clost time.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2010-09-07 19:21:20 -04:00

372 lines
7.8 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/sunrpc/clnt.h>
#include <linux/dns_resolver.h>
ssize_t nfs_dns_resolve_name(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(ip_addr, ip_len, sa, salen);
else
ret = -ESRCH;
kfree(ip_addr);
return ret;
}
#else
#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 "dns_resolve.h"
#include "cache_lib.h"
#define NFS_DNS_HASHBITS 4
#define NFS_DNS_HASHTBL_SIZE (1 << NFS_DNS_HASHBITS)
static struct cache_head *nfs_dns_table[NFS_DNS_HASHTBL_SIZE];
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(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 struct cache_detail nfs_dns_resolve = {
.owner = THIS_MODULE,
.hash_size = NFS_DNS_HASHTBL_SIZE,
.hash_table = nfs_dns_table,
.name = "dns_resolve",
.cache_put = nfs_dns_ent_put,
.cache_upcall = nfs_dns_upcall,
.cache_parse = nfs_dns_parse,
.cache_show = nfs_dns_show,
.match = nfs_dns_match,
.init = nfs_dns_ent_init,
.update = nfs_dns_ent_update,
.alloc = nfs_dns_ent_alloc,
};
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(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;
ret = do_cache_lookup_wait(&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, &nfs_dns_resolve);
} else if (ret == -ENOENT)
ret = -ESRCH;
return ret;
}
int nfs_dns_resolver_init(void)
{
return nfs_cache_register(&nfs_dns_resolve);
}
void nfs_dns_resolver_destroy(void)
{
nfs_cache_unregister(&nfs_dns_resolve);
}
#endif