[mirror_ubuntu-bionic-kernel.git] / fs / nfs / dns_resolve.c

/*
 * linux/fs/nfs/dns_resolve.c
 *
 * Copyright (c) 2009 Trond Myklebust <Trond.Myklebust@netapp.com>
 *
 * Resolves DNS hostnames into valid ip addresses
 */

#include <linux/hash.h>
#include <linux/string.h>
#include <linux/kmod.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 = (long)item->h.expiry_time - (long)get_seconds();
	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 + get_seconds();

	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 < get_seconds()
			|| 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);
}
Commit	Line	Data
e571cbf1 TM	1	/*
	2	* linux/fs/nfs/dns_resolve.c
	3	*
	4	* Copyright (c) 2009 Trond Myklebust <Trond.Myklebust@netapp.com>
	5	*
	6	* Resolves DNS hostnames into valid ip addresses
	7	*/
	8
	9	#include <linux/hash.h>
	10	#include <linux/string.h>
	11	#include <linux/kmod.h>
	12	#include <linux/module.h>
	13	#include <linux/socket.h>
	14	#include <linux/seq_file.h>
	15	#include <linux/inet.h>
	16	#include <linux/sunrpc/clnt.h>
	17	#include <linux/sunrpc/cache.h>
	18	#include <linux/sunrpc/svcauth.h>
	19
	20	#include "dns_resolve.h"
	21	#include "cache_lib.h"
	22
	23	#define NFS_DNS_HASHBITS 4
	24	#define NFS_DNS_HASHTBL_SIZE (1 << NFS_DNS_HASHBITS)
	25
	26	static struct cache_head *nfs_dns_table[NFS_DNS_HASHTBL_SIZE];
	27
	28	struct nfs_dns_ent {
	29	struct cache_head h;
	30
	31	char *hostname;
	32	size_t namelen;
	33
	34	struct sockaddr_storage addr;
	35	size_t addrlen;
	36	};
	37
	38
ebed9203 TM	39	static void nfs_dns_ent_update(struct cache_head *cnew,
	40	struct cache_head *ckey)
	41	{
	42	struct nfs_dns_ent *new;
	43	struct nfs_dns_ent *key;
	44
	45	new = container_of(cnew, struct nfs_dns_ent, h);
	46	key = container_of(ckey, struct nfs_dns_ent, h);
	47
	48	memcpy(&new->addr, &key->addr, key->addrlen);
	49	new->addrlen = key->addrlen;
	50	}
	51
e571cbf1 TM	52	static void nfs_dns_ent_init(struct cache_head *cnew,
	53	struct cache_head *ckey)
	54	{
	55	struct nfs_dns_ent *new;
	56	struct nfs_dns_ent *key;
	57
	58	new = container_of(cnew, struct nfs_dns_ent, h);
	59	key = container_of(ckey, struct nfs_dns_ent, h);
	60
	61	kfree(new->hostname);
	62	new->hostname = kstrndup(key->hostname, key->namelen, GFP_KERNEL);
	63	if (new->hostname) {
	64	new->namelen = key->namelen;
ebed9203	65	nfs_dns_ent_update(cnew, ckey);
e571cbf1 TM	66	} else {
	67	new->namelen = 0;
	68	new->addrlen = 0;
	69	}
	70	}
	71
	72	static void nfs_dns_ent_put(struct kref *ref)
	73	{
	74	struct nfs_dns_ent *item;
	75
	76	item = container_of(ref, struct nfs_dns_ent, h.ref);
	77	kfree(item->hostname);
	78	kfree(item);
	79	}
	80
	81	static struct cache_head *nfs_dns_ent_alloc(void)
	82	{
	83	struct nfs_dns_ent item = kmalloc(sizeof(item), GFP_KERNEL);
	84
	85	if (item != NULL) {
	86	item->hostname = NULL;
	87	item->namelen = 0;
	88	item->addrlen = 0;
	89	return &item->h;
	90	}
	91	return NULL;
	92	};
	93
	94	static unsigned int nfs_dns_hash(const struct nfs_dns_ent *key)
	95	{
	96	return hash_str(key->hostname, NFS_DNS_HASHBITS);
	97	}
	98
	99	static void nfs_dns_request(struct cache_detail *cd,
	100	struct cache_head *ch,
	101	char *bpp, int blen)
	102	{
	103	struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h);
	104
	105	qword_add(bpp, blen, key->hostname);
	106	(*bpp)[-1] = '\n';
	107	}
	108
	109	static int nfs_dns_upcall(struct cache_detail *cd,
	110	struct cache_head *ch)
	111	{
	112	struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h);
	113	int ret;
	114
	115	ret = nfs_cache_upcall(cd, key->hostname);
	116	if (ret)
	117	ret = sunrpc_cache_pipe_upcall(cd, ch, nfs_dns_request);
	118	return ret;
	119	}
	120
	121	static int nfs_dns_match(struct cache_head *ca,
	122	struct cache_head *cb)
	123	{
	124	struct nfs_dns_ent *a;
	125	struct nfs_dns_ent *b;
	126
	127	a = container_of(ca, struct nfs_dns_ent, h);
	128	b = container_of(cb, struct nfs_dns_ent, h);
	129
130	if (a->namelen == 0 \|\| a->namelen != b->namelen)
131	return 0;
132	return memcmp(a->hostname, b->hostname, a->namelen) == 0;
133	}
134
135	static int nfs_dns_show(struct seq_file m, struct cache_detail cd,
136	struct cache_head *h)
137	{
138	struct nfs_dns_ent *item;
139	long ttl;
140
141	if (h == NULL) {
142	seq_puts(m, "# ip address hostname ttl\n");
143	return 0;
144	}
145	item = container_of(h, struct nfs_dns_ent, h);
146	ttl = (long)item->h.expiry_time - (long)get_seconds();
147	if (ttl < 0)
148	ttl = 0;
149
150	if (!test_bit(CACHE_NEGATIVE, &h->flags)) {
151	char buf[INET6_ADDRSTRLEN+IPV6_SCOPE_ID_LEN+1];
152
153	rpc_ntop((struct sockaddr *)&item->addr, buf, sizeof(buf));
154	seq_printf(m, "%15s ", buf);
155	} else
156	seq_puts(m, "<none> ");
157	seq_printf(m, "%15s %ld\n", item->hostname, ttl);
158	return 0;
159	}
160
0a6566ec	161	static struct nfs_dns_ent nfs_dns_lookup(struct cache_detail cd,
e571cbf1 TM	162	struct nfs_dns_ent *key)
	163	{
	164	struct cache_head *ch;
	165
	166	ch = sunrpc_cache_lookup(cd,
	167	&key->h,
	168	nfs_dns_hash(key));
	169	if (!ch)
	170	return NULL;
	171	return container_of(ch, struct nfs_dns_ent, h);
	172	}
	173
0a6566ec	174	static struct nfs_dns_ent nfs_dns_update(struct cache_detail cd,
e571cbf1 TM	175	struct nfs_dns_ent *new,
	176	struct nfs_dns_ent *key)
	177	{
	178	struct cache_head *ch;
	179
	180	ch = sunrpc_cache_update(cd,
	181	&new->h, &key->h,
	182	nfs_dns_hash(key));
	183	if (!ch)
	184	return NULL;
	185	return container_of(ch, struct nfs_dns_ent, h);
	186	}
	187
	188	static int nfs_dns_parse(struct cache_detail cd, char buf, int buflen)
	189	{
	190	char buf1[NFS_DNS_HOSTNAME_MAXLEN+1];
	191	struct nfs_dns_ent key, *item;
	192	unsigned long ttl;
	193	ssize_t len;
	194	int ret = -EINVAL;
	195
	196	if (buf[buflen-1] != '\n')
	197	goto out;
	198	buf[buflen-1] = '\0';
	199
	200	len = qword_get(&buf, buf1, sizeof(buf1));
	201	if (len <= 0)
	202	goto out;
	203	key.addrlen = rpc_pton(buf1, len,
	204	(struct sockaddr *)&key.addr,
	205	sizeof(key.addr));
	206
	207	len = qword_get(&buf, buf1, sizeof(buf1));
	208	if (len <= 0)
	209	goto out;
	210
	211	key.hostname = buf1;
	212	key.namelen = len;
	213	memset(&key.h, 0, sizeof(key.h));
	214
	215	ttl = get_expiry(&buf);
	216	if (ttl == 0)
	217	goto out;
	218	key.h.expiry_time = ttl + get_seconds();
	219
	220	ret = -ENOMEM;
	221	item = nfs_dns_lookup(cd, &key);
	222	if (item == NULL)
	223	goto out;
	224
	225	if (key.addrlen == 0)
	226	set_bit(CACHE_NEGATIVE, &key.h.flags);
	227
	228	item = nfs_dns_update(cd, &key, item);
	229	if (item == NULL)
	230	goto out;
	231
	232	ret = 0;
	233	cache_put(&item->h, cd);
	234	out:
	235	return ret;
	236	}
	237
	238	static struct cache_detail nfs_dns_resolve = {
239	.owner = THIS_MODULE,
240	.hash_size = NFS_DNS_HASHTBL_SIZE,
241	.hash_table = nfs_dns_table,
242	.name = "dns_resolve",
243	.cache_put = nfs_dns_ent_put,
244	.cache_upcall = nfs_dns_upcall,
245	.cache_parse = nfs_dns_parse,
246	.cache_show = nfs_dns_show,
247	.match = nfs_dns_match,
248	.init = nfs_dns_ent_init,
ebed9203	249	.update = nfs_dns_ent_update,
e571cbf1 TM	250	.alloc = nfs_dns_ent_alloc,
	251	};
	252
	253	static int do_cache_lookup(struct cache_detail *cd,
	254	struct nfs_dns_ent *key,
	255	struct nfs_dns_ent **item,
	256	struct nfs_cache_defer_req *dreq)
	257	{
	258	int ret = -ENOMEM;
	259
	260	*item = nfs_dns_lookup(cd, key);
	261	if (*item) {
	262	ret = cache_check(cd, &(*item)->h, &dreq->req);
	263	if (ret)
	264	*item = NULL;
	265	}
	266	return ret;
	267	}
	268
	269	static int do_cache_lookup_nowait(struct cache_detail *cd,
	270	struct nfs_dns_ent *key,
	271	struct nfs_dns_ent **item)
	272	{
	273	int ret = -ENOMEM;
	274
	275	*item = nfs_dns_lookup(cd, key);
	276	if (!*item)
	277	goto out_err;
	278	ret = -ETIMEDOUT;
	279	if (!test_bit(CACHE_VALID, &(*item)->h.flags)
	280	\|\| (*item)->h.expiry_time < get_seconds()
	281	\|\| cd->flush_time > (*item)->h.last_refresh)
	282	goto out_put;
	283	ret = -ENOENT;
	284	if (test_bit(CACHE_NEGATIVE, &(*item)->h.flags))
	285	goto out_put;
	286	return 0;
	287	out_put:
	288	cache_put(&(*item)->h, cd);
	289	out_err:
	290	*item = NULL;
	291	return ret;
	292	}
	293
	294	static int do_cache_lookup_wait(struct cache_detail *cd,
	295	struct nfs_dns_ent *key,
	296	struct nfs_dns_ent **item)
	297	{
	298	struct nfs_cache_defer_req *dreq;
	299	int ret = -ENOMEM;
	300
	301	dreq = nfs_cache_defer_req_alloc();
	302	if (!dreq)
	303	goto out;
	304	ret = do_cache_lookup(cd, key, item, dreq);
	305	if (ret == -EAGAIN) {
	306	ret = nfs_cache_wait_for_upcall(dreq);
	307	if (!ret)
	308	ret = do_cache_lookup_nowait(cd, key, item);
	309	}
	310	nfs_cache_defer_req_put(dreq);
	311	out:
	312	return ret;
	313	}
314
315	ssize_t nfs_dns_resolve_name(char *name, size_t namelen,
316	struct sockaddr *sa, size_t salen)
317	{
318	struct nfs_dns_ent key = {
319	.hostname = name,
320	.namelen = namelen,
321	};
322	struct nfs_dns_ent *item = NULL;
323	ssize_t ret;
324
325	ret = do_cache_lookup_wait(&nfs_dns_resolve, &key, &item);
326	if (ret == 0) {
327	if (salen >= item->addrlen) {
328	memcpy(sa, &item->addr, item->addrlen);
329	ret = item->addrlen;
330	} else
331	ret = -EOVERFLOW;
332	cache_put(&item->h, &nfs_dns_resolve);
333	} else if (ret == -ENOENT)
334	ret = -ESRCH;
335	return ret;
336	}
337
338	int nfs_dns_resolver_init(void)
339	{
340	return nfs_cache_register(&nfs_dns_resolve);
341	}
342
343	void nfs_dns_resolver_destroy(void)
344	{
345	nfs_cache_unregister(&nfs_dns_resolve);
346	}
347