[linux-2.6-block.git] / fs / afs / addr_list.c

/* Server address list management
 *
 * Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public Licence
 * as published by the Free Software Foundation; either version
 * 2 of the Licence, or (at your option) any later version.
 */

#include <linux/slab.h>
#include <linux/ctype.h>
#include <linux/dns_resolver.h>
#include <linux/inet.h>
#include <keys/rxrpc-type.h>
#include "internal.h"
#include "afs_fs.h"

/*
 * Release an address list.
 */
void afs_put_addrlist(struct afs_addr_list *alist)
{
	if (alist && refcount_dec_and_test(&alist->usage))
		call_rcu(&alist->rcu, (rcu_callback_t)kfree);
}

/*
 * Allocate an address list.
 */
struct afs_addr_list *afs_alloc_addrlist(unsigned int nr,
					 unsigned short service,
					 unsigned short port)
{
	struct afs_addr_list *alist;
	unsigned int i;

	_enter("%u,%u,%u", nr, service, port);

	if (nr > AFS_MAX_ADDRESSES)
		nr = AFS_MAX_ADDRESSES;

	alist = kzalloc(struct_size(alist, addrs, nr), GFP_KERNEL);
	if (!alist)
		return NULL;

	refcount_set(&alist->usage, 1);
	alist->max_addrs = nr;

	for (i = 0; i < nr; i++) {
		struct sockaddr_rxrpc *srx = &alist->addrs[i];
		srx->srx_family			= AF_RXRPC;
		srx->srx_service		= service;
		srx->transport_type		= SOCK_DGRAM;
		srx->transport_len		= sizeof(srx->transport.sin6);
		srx->transport.sin6.sin6_family	= AF_INET6;
		srx->transport.sin6.sin6_port	= htons(port);
	}

	return alist;
}

/*
 * Parse a text string consisting of delimited addresses.
 */
struct afs_addr_list *afs_parse_text_addrs(const char *text, size_t len,
					   char delim,
					   unsigned short service,
					   unsigned short port)
{
	struct afs_addr_list *alist;
	const char *p, *end = text + len;
	unsigned int nr = 0;

	_enter("%*.*s,%c", (int)len, (int)len, text, delim);

	if (!len)
		return ERR_PTR(-EDESTADDRREQ);

	if (delim == ':' && (memchr(text, ',', len) || !memchr(text, '.', len)))
		delim = ',';

	/* Count the addresses */
	p = text;
	do {
		if (!*p)
			return ERR_PTR(-EINVAL);
		if (*p == delim)
			continue;
		nr++;
		if (*p == '[') {
			p++;
			if (p == end)
				return ERR_PTR(-EINVAL);
			p = memchr(p, ']', end - p);
			if (!p)
				return ERR_PTR(-EINVAL);
			p++;
			if (p >= end)
				break;
		}

		p = memchr(p, delim, end - p);
		if (!p)
			break;
		p++;
	} while (p < end);

	_debug("%u/%u addresses", nr, AFS_MAX_ADDRESSES);

	alist = afs_alloc_addrlist(nr, service, port);
	if (!alist)
		return ERR_PTR(-ENOMEM);

	/* Extract the addresses */
	p = text;
	do {
		const char *q, *stop;
		unsigned int xport = port;
		__be32 x[4];
		int family;

		if (*p == delim) {
			p++;
			continue;
		}

		if (*p == '[') {
			p++;
			q = memchr(p, ']', end - p);
		} else {
			for (q = p; q < end; q++)
				if (*q == '+' || *q == delim)
					break;
		}

		if (in4_pton(p, q - p, (u8 *)&x[0], -1, &stop))
			family = AF_INET;
		else if (in6_pton(p, q - p, (u8 *)x, -1, &stop))
			family = AF_INET6;
		else
			goto bad_address;

		if (stop != q)
			goto bad_address;

		p = q;
		if (q < end && *q == ']')
			p++;

		if (p < end) {
			if (*p == '+') {
				/* Port number specification "+1234" */
				xport = 0;
				p++;
				if (p >= end || !isdigit(*p))
					goto bad_address;
				do {
					xport *= 10;
					xport += *p - '0';
					if (xport > 65535)
						goto bad_address;
					p++;
				} while (p < end && isdigit(*p));
			} else if (*p == delim) {
				p++;
			} else {
				goto bad_address;
			}
		}

		if (family == AF_INET)
			afs_merge_fs_addr4(alist, x[0], xport);
		else
			afs_merge_fs_addr6(alist, x, xport);

	} while (p < end);

	_leave(" = [nr %u]", alist->nr_addrs);
	return alist;

bad_address:
	kfree(alist);
	return ERR_PTR(-EINVAL);
}

/*
 * Compare old and new address lists to see if there's been any change.
 * - How to do this in better than O(Nlog(N)) time?
 *   - We don't really want to sort the address list, but would rather take the
 *     list as we got it so as not to undo record rotation by the DNS server.
 */
#if 0
static int afs_cmp_addr_list(const struct afs_addr_list *a1,
			     const struct afs_addr_list *a2)
{
}
#endif

/*
 * Perform a DNS query for VL servers and build a up an address list.
 */
struct afs_addr_list *afs_dns_query(struct afs_cell *cell, time64_t *_expiry)
{
	struct afs_addr_list *alist;
	char *vllist = NULL;
	int ret;

	_enter("%s", cell->name);

	ret = dns_query("afsdb", cell->name, cell->name_len,
			"", &vllist, _expiry);
	if (ret < 0)
		return ERR_PTR(ret);

	alist = afs_parse_text_addrs(vllist, strlen(vllist), ',',
				     VL_SERVICE, AFS_VL_PORT);
	if (IS_ERR(alist)) {
		kfree(vllist);
		if (alist != ERR_PTR(-ENOMEM))
			pr_err("Failed to parse DNS data\n");
		return alist;
	}

	kfree(vllist);
	return alist;
}

/*
 * Merge an IPv4 entry into a fileserver address list.
 */
void afs_merge_fs_addr4(struct afs_addr_list *alist, __be32 xdr, u16 port)
{
	struct sockaddr_rxrpc *srx;
	u32 addr = ntohl(xdr);
	int i;

	if (alist->nr_addrs >= alist->max_addrs)
		return;

	for (i = 0; i < alist->nr_ipv4; i++) {
		struct sockaddr_in *a = &alist->addrs[i].transport.sin;
		u32 a_addr = ntohl(a->sin_addr.s_addr);
		u16 a_port = ntohs(a->sin_port);

		if (addr == a_addr && port == a_port)
			return;
		if (addr == a_addr && port < a_port)
			break;
		if (addr < a_addr)
			break;
	}

	if (i < alist->nr_addrs)
		memmove(alist->addrs + i + 1,
			alist->addrs + i,
			sizeof(alist->addrs[0]) * (alist->nr_addrs - i));

	srx = &alist->addrs[i];
	srx->transport_len = sizeof(srx->transport.sin);
	srx->transport.sin.sin_family = AF_INET;
	srx->transport.sin.sin_port = htons(port);
	srx->transport.sin.sin_addr.s_addr = xdr;
	alist->nr_ipv4++;
	alist->nr_addrs++;
}

/*
 * Merge an IPv6 entry into a fileserver address list.
 */
void afs_merge_fs_addr6(struct afs_addr_list *alist, __be32 *xdr, u16 port)
{
	struct sockaddr_rxrpc *srx;
	int i, diff;

	if (alist->nr_addrs >= alist->max_addrs)
		return;

	for (i = alist->nr_ipv4; i < alist->nr_addrs; i++) {
		struct sockaddr_in6 *a = &alist->addrs[i].transport.sin6;
		u16 a_port = ntohs(a->sin6_port);

		diff = memcmp(xdr, &a->sin6_addr, 16);
		if (diff == 0 && port == a_port)
			return;
		if (diff == 0 && port < a_port)
			break;
		if (diff < 0)
			break;
	}

	if (i < alist->nr_addrs)
		memmove(alist->addrs + i + 1,
			alist->addrs + i,
			sizeof(alist->addrs[0]) * (alist->nr_addrs - i));

	srx = &alist->addrs[i];
	srx->transport_len = sizeof(srx->transport.sin6);
	srx->transport.sin6.sin6_family = AF_INET6;
	srx->transport.sin6.sin6_port = htons(port);
	memcpy(&srx->transport.sin6.sin6_addr, xdr, 16);
	alist->nr_addrs++;
}

/*
 * Get an address to try.
 */
bool afs_iterate_addresses(struct afs_addr_cursor *ac)
{
	_enter("%hu+%hd", ac->start, (short)ac->index);

	if (!ac->alist)
		return false;

	if (ac->begun) {
		ac->index++;
		if (ac->index == ac->alist->nr_addrs)
			ac->index = 0;

		if (ac->index == ac->start) {
			ac->error = -EDESTADDRREQ;
			return false;
		}
	}

	ac->begun = true;
	ac->responded = false;
	ac->addr = &ac->alist->addrs[ac->index];
	return true;
}

/*
 * Release an address list cursor.
 */
int afs_end_cursor(struct afs_addr_cursor *ac)
{
	struct afs_addr_list *alist;

	alist = ac->alist;
	if (alist) {
		if (ac->responded && ac->index != ac->start)
			WRITE_ONCE(alist->index, ac->index);
		afs_put_addrlist(alist);
	}

	ac->addr = NULL;
	ac->alist = NULL;
	ac->begun = false;
	return ac->error;
}

/*
 * Set the address cursor for iterating over VL servers.
 */
int afs_set_vl_cursor(struct afs_addr_cursor *ac, struct afs_cell *cell)
{
	struct afs_addr_list *alist;
	int ret;

	if (!rcu_access_pointer(cell->vl_addrs)) {
		ret = wait_on_bit(&cell->flags, AFS_CELL_FL_NO_LOOKUP_YET,
				  TASK_INTERRUPTIBLE);
		if (ret < 0)
			return ret;

		if (!rcu_access_pointer(cell->vl_addrs) &&
		    ktime_get_real_seconds() < cell->dns_expiry)
			return cell->error;
	}

	read_lock(&cell->vl_addrs_lock);
	alist = rcu_dereference_protected(cell->vl_addrs,
					  lockdep_is_held(&cell->vl_addrs_lock));
	if (alist->nr_addrs > 0)
		afs_get_addrlist(alist);
	else
		alist = NULL;
	read_unlock(&cell->vl_addrs_lock);

	if (!alist)
		return -EDESTADDRREQ;

	ac->alist = alist;
	ac->addr = NULL;
	ac->start = READ_ONCE(alist->index);
	ac->index = ac->start;
	ac->error = 0;
	ac->begun = false;
	return 0;
}
Commit	Line	Data
8b2a464c DH	1	/* Server address list management
	2	*
	3	* Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
	4	* Written by David Howells (dhowells@redhat.com)
	5	*
	6	* This program is free software; you can redistribute it and/or
	7	* modify it under the terms of the GNU General Public Licence
	8	* as published by the Free Software Foundation; either version
	9	* 2 of the Licence, or (at your option) any later version.
	10	*/
	11
	12	#include <linux/slab.h>
	13	#include <linux/ctype.h>
	14	#include <linux/dns_resolver.h>
	15	#include <linux/inet.h>
	16	#include <keys/rxrpc-type.h>
	17	#include "internal.h"
	18	#include "afs_fs.h"
	19
8b2a464c DH	20	/*
	21	* Release an address list.
	22	*/
	23	void afs_put_addrlist(struct afs_addr_list *alist)
	24	{
	25	if (alist && refcount_dec_and_test(&alist->usage))
	26	call_rcu(&alist->rcu, (rcu_callback_t)kfree);
	27	}
	28
	29	/*
	30	* Allocate an address list.
	31	*/
	32	struct afs_addr_list *afs_alloc_addrlist(unsigned int nr,
	33	unsigned short service,
	34	unsigned short port)
	35	{
	36	struct afs_addr_list *alist;
	37	unsigned int i;
	38
	39	_enter("%u,%u,%u", nr, service, port);
	40
68eb64c3 DH	41	if (nr > AFS_MAX_ADDRESSES)
	42	nr = AFS_MAX_ADDRESSES;
	43
acafe7e3	44	alist = kzalloc(struct_size(alist, addrs, nr), GFP_KERNEL);
8b2a464c DH	45	if (!alist)
	46	return NULL;
	47
	48	refcount_set(&alist->usage, 1);
68eb64c3	49	alist->max_addrs = nr;
8b2a464c DH	50
	51	for (i = 0; i < nr; i++) {
	52	struct sockaddr_rxrpc *srx = &alist->addrs[i];
	53	srx->srx_family = AF_RXRPC;
	54	srx->srx_service = service;
	55	srx->transport_type = SOCK_DGRAM;
	56	srx->transport_len = sizeof(srx->transport.sin6);
	57	srx->transport.sin6.sin6_family = AF_INET6;
	58	srx->transport.sin6.sin6_port = htons(port);
	59	}
	60
	61	return alist;
	62	}
	63
	64	/*
	65	* Parse a text string consisting of delimited addresses.
	66	*/
	67	struct afs_addr_list afs_parse_text_addrs(const char text, size_t len,
	68	char delim,
	69	unsigned short service,
	70	unsigned short port)
	71	{
	72	struct afs_addr_list *alist;
	73	const char p, end = text + len;
	74	unsigned int nr = 0;
	75
	76	_enter("%.s,%c", (int)len, (int)len, text, delim);
	77
	78	if (!len)
	79	return ERR_PTR(-EDESTADDRREQ);
	80
	81	if (delim == ':' && (memchr(text, ',', len) \|\| !memchr(text, '.', len)))
	82	delim = ',';
	83
	84	/* Count the addresses */
	85	p = text;
	86	do {
	87	if (!*p)
	88	return ERR_PTR(-EINVAL);
	89	if (*p == delim)
	90	continue;
	91	nr++;
	92	if (*p == '[') {
	93	p++;
	94	if (p == end)
	95	return ERR_PTR(-EINVAL);
	96	p = memchr(p, ']', end - p);
	97	if (!p)
	98	return ERR_PTR(-EINVAL);
	99	p++;
	100	if (p >= end)
	101	break;
	102	}
	103
	104	p = memchr(p, delim, end - p);
	105	if (!p)
	106	break;
	107	p++;
	108	} while (p < end);
	109
	110	_debug("%u/%u addresses", nr, AFS_MAX_ADDRESSES);
8b2a464c DH	111
	112	alist = afs_alloc_addrlist(nr, service, port);
	113	if (!alist)
	114	return ERR_PTR(-ENOMEM);
	115
	116	/* Extract the addresses */
	117	p = text;
	118	do {
01fd79e6	119	const char q, stop;
4c19bbdc DH	120	unsigned int xport = port;
	121	__be32 x[4];
	122	int family;
8b2a464c DH	123
	124	if (*p == delim) {
	125	p++;
	126	continue;
	127	}
	128
	129	if (*p == '[') {
	130	p++;
01fd79e6 DH	131	q = memchr(p, ']', end - p);
	132	} else {
	133	for (q = p; q < end; q++)
	134	if (q == '+' \|\| q == delim)
	135	break;
8b2a464c DH	136	}
8b2a464c DH	137
4c19bbdc DH	138	if (in4_pton(p, q - p, (u8 *)&x[0], -1, &stop))
	139	family = AF_INET;
	140	else if (in6_pton(p, q - p, (u8 *)x, -1, &stop))
	141	family = AF_INET6;
	142	else
8b2a464c	143	goto bad_address;
8b2a464c	144
01fd79e6 DH	145	if (stop != q)
	146	goto bad_address;
	147
	148	p = q;
	149	if (q < end && *q == ']')
8b2a464c	150	p++;
8b2a464c DH	151
	152	if (p < end) {
	153	if (*p == '+') {
	154	/* Port number specification "+1234" */
4c19bbdc	155	xport = 0;
8b2a464c DH	156	p++;
	157	if (p >= end \|\| !isdigit(*p))
	158	goto bad_address;
	159	do {
	160	xport *= 10;
	161	xport += *p - '0';
	162	if (xport > 65535)
	163	goto bad_address;
	164	p++;
	165	} while (p < end && isdigit(*p));
8b2a464c DH	166	} else if (*p == delim) {
	167	p++;
	168	} else {
	169	goto bad_address;
	170	}
	171	}
	172
4c19bbdc DH	173	if (family == AF_INET)
	174	afs_merge_fs_addr4(alist, x[0], xport);
	175	else
	176	afs_merge_fs_addr6(alist, x, xport);
	177
	178	} while (p < end);
8b2a464c DH	179
	180	_leave(" = [nr %u]", alist->nr_addrs);
	181	return alist;
	182
	183	bad_address:
	184	kfree(alist);
	185	return ERR_PTR(-EINVAL);
	186	}
	187
	188	/*
	189	* Compare old and new address lists to see if there's been any change.
	190	* - How to do this in better than O(Nlog(N)) time?
	191	* - We don't really want to sort the address list, but would rather take the
	192	* list as we got it so as not to undo record rotation by the DNS server.
	193	*/
	194	#if 0
	195	static int afs_cmp_addr_list(const struct afs_addr_list *a1,
	196	const struct afs_addr_list *a2)
	197	{
	198	}
	199	#endif
	200
	201	/*
	202	* Perform a DNS query for VL servers and build a up an address list.
	203	*/
	204	struct afs_addr_list afs_dns_query(struct afs_cell cell, time64_t *_expiry)
	205	{
	206	struct afs_addr_list *alist;
	207	char *vllist = NULL;
	208	int ret;
	209
	210	_enter("%s", cell->name);
	211
	212	ret = dns_query("afsdb", cell->name, cell->name_len,
c88d5a7f	213	"", &vllist, _expiry);
8b2a464c DH	214	if (ret < 0)
	215	return ERR_PTR(ret);
	216
	217	alist = afs_parse_text_addrs(vllist, strlen(vllist), ',',
	218	VL_SERVICE, AFS_VL_PORT);
	219	if (IS_ERR(alist)) {
	220	kfree(vllist);
	221	if (alist != ERR_PTR(-ENOMEM))
	222	pr_err("Failed to parse DNS data\n");
	223	return alist;
	224	}
	225
	226	kfree(vllist);
	227	return alist;
	228	}
	229
d2ddc776 DH	230	/*
	231	* Merge an IPv4 entry into a fileserver address list.
	232	*/
bf99a53c	233	void afs_merge_fs_addr4(struct afs_addr_list *alist, __be32 xdr, u16 port)
d2ddc776	234	{
46894a13	235	struct sockaddr_rxrpc *srx;
66be646b	236	u32 addr = ntohl(xdr);
d2ddc776 DH	237	int i;
d2ddc776 DH	238
68eb64c3 DH	239	if (alist->nr_addrs >= alist->max_addrs)
	240	return;
	241
d2ddc776	242	for (i = 0; i < alist->nr_ipv4; i++) {
46894a13 DH	243	struct sockaddr_in *a = &alist->addrs[i].transport.sin;
	244	u32 a_addr = ntohl(a->sin_addr.s_addr);
	245	u16 a_port = ntohs(a->sin_port);
66be646b DH	246
66be646b DH	247	if (addr == a_addr && port == a_port)
d2ddc776	248	return;
66be646b	249	if (addr == a_addr && port < a_port)
bf99a53c	250	break;
66be646b	251	if (addr < a_addr)
d2ddc776 DH	252	break;
	253	}
	254
	255	if (i < alist->nr_addrs)
	256	memmove(alist->addrs + i + 1,
	257	alist->addrs + i,
	258	sizeof(alist->addrs[0]) * (alist->nr_addrs - i));
	259
46894a13 DH	260	srx = &alist->addrs[i];
	261	srx->transport_len = sizeof(srx->transport.sin);
	262	srx->transport.sin.sin_family = AF_INET;
	263	srx->transport.sin.sin_port = htons(port);
	264	srx->transport.sin.sin_addr.s_addr = xdr;
d2ddc776 DH	265	alist->nr_ipv4++;
	266	alist->nr_addrs++;
	267	}
	268
bf99a53c DH	269	/*
	270	* Merge an IPv6 entry into a fileserver address list.
	271	*/
	272	void afs_merge_fs_addr6(struct afs_addr_list alist, __be32 xdr, u16 port)
	273	{
46894a13	274	struct sockaddr_rxrpc *srx;
bf99a53c DH	275	int i, diff;
bf99a53c DH	276
68eb64c3 DH	277	if (alist->nr_addrs >= alist->max_addrs)
	278	return;
	279
bf99a53c	280	for (i = alist->nr_ipv4; i < alist->nr_addrs; i++) {
66be646b DH	281	struct sockaddr_in6 *a = &alist->addrs[i].transport.sin6;
	282	u16 a_port = ntohs(a->sin6_port);
	283
bf99a53c	284	diff = memcmp(xdr, &a->sin6_addr, 16);
66be646b	285	if (diff == 0 && port == a_port)
bf99a53c	286	return;
66be646b	287	if (diff == 0 && port < a_port)
bf99a53c DH	288	break;
	289	if (diff < 0)
	290	break;
	291	}
	292
	293	if (i < alist->nr_addrs)
	294	memmove(alist->addrs + i + 1,
	295	alist->addrs + i,
	296	sizeof(alist->addrs[0]) * (alist->nr_addrs - i));
	297
46894a13 DH	298	srx = &alist->addrs[i];
	299	srx->transport_len = sizeof(srx->transport.sin6);
	300	srx->transport.sin6.sin6_family = AF_INET6;
	301	srx->transport.sin6.sin6_port = htons(port);
	302	memcpy(&srx->transport.sin6.sin6_addr, xdr, 16);
bf99a53c DH	303	alist->nr_addrs++;
	304	}
	305
8b2a464c DH	306	/*
	307	* Get an address to try.
	308	*/
	309	bool afs_iterate_addresses(struct afs_addr_cursor *ac)
	310	{
	311	_enter("%hu+%hd", ac->start, (short)ac->index);
	312
	313	if (!ac->alist)
	314	return false;
	315
	316	if (ac->begun) {
	317	ac->index++;
	318	if (ac->index == ac->alist->nr_addrs)
	319	ac->index = 0;
	320
	321	if (ac->index == ac->start) {
	322	ac->error = -EDESTADDRREQ;
	323	return false;
	324	}
	325	}
	326
	327	ac->begun = true;
	328	ac->responded = false;
	329	ac->addr = &ac->alist->addrs[ac->index];
	330	return true;
	331	}
	332
	333	/*
	334	* Release an address list cursor.
	335	*/
	336	int afs_end_cursor(struct afs_addr_cursor *ac)
	337	{
fe4d774c DH	338	struct afs_addr_list *alist;
	339
	340	alist = ac->alist;
	341	if (alist) {
	342	if (ac->responded && ac->index != ac->start)
	343	WRITE_ONCE(alist->index, ac->index);
	344	afs_put_addrlist(alist);
	345	}
8b2a464c	346
fe4d774c	347	ac->addr = NULL;
8b2a464c	348	ac->alist = NULL;
fe4d774c	349	ac->begun = false;
8b2a464c DH	350	return ac->error;
	351	}
	352
	353	/*
	354	* Set the address cursor for iterating over VL servers.
	355	*/
	356	int afs_set_vl_cursor(struct afs_addr_cursor ac, struct afs_cell cell)
	357	{
	358	struct afs_addr_list *alist;
	359	int ret;
	360
	361	if (!rcu_access_pointer(cell->vl_addrs)) {
	362	ret = wait_on_bit(&cell->flags, AFS_CELL_FL_NO_LOOKUP_YET,
	363	TASK_INTERRUPTIBLE);
	364	if (ret < 0)
	365	return ret;
	366
	367	if (!rcu_access_pointer(cell->vl_addrs) &&
	368	ktime_get_real_seconds() < cell->dns_expiry)
	369	return cell->error;
	370	}
	371
	372	read_lock(&cell->vl_addrs_lock);
	373	alist = rcu_dereference_protected(cell->vl_addrs,
	374	lockdep_is_held(&cell->vl_addrs_lock));
	375	if (alist->nr_addrs > 0)
	376	afs_get_addrlist(alist);
	377	else
	378	alist = NULL;
	379	read_unlock(&cell->vl_addrs_lock);
	380
	381	if (!alist)
	382	return -EDESTADDRREQ;
	383
	384	ac->alist = alist;
	385	ac->addr = NULL;
	386	ac->start = READ_ONCE(alist->index);
	387	ac->index = ac->start;
	388	ac->error = 0;
	389	ac->begun = false;
	390	return 0;
	391	}