linux-stable/fs/afs/addr_list.c
David Howells bf99a53ce2 afs: Make use of the YFS service upgrade to fully support IPv6
YFS VL servers offer an upgraded Volume Location service that can return
IPv6 addresses to fileservers and volume servers in addition to IPv4
addresses using the YFSVL.GetEndpoints operation which we should use if
it's available.

To this end:

 (1) Make rxrpc_kernel_recv_data() return the call's current service ID so
     that the caller can detect service upgrade and see what the service
     was upgraded to.

 (2) When we see a VL server address we haven't seen before, send a
     VL.GetCapabilities operation to it with the service upgrade bit set.

     If we get an upgrade to the YFS VL service, change the service ID in
     the address list for that address to use the upgraded service and set
     a flag to note that this appears to be a YFS-compatible server.

 (3) If, when a server's addresses are being looked up, we note that we
     previously detected a YFS-compatible server, then send the
     YFSVL.GetEndpoints operation rather than VL.GetAddrsU.

 (4) Build a fileserver address list from the reply of YFSVL.GetEndpoints,
     including both IPv4 and IPv6 addresses.  Volume server addresses are
     discarded.

 (5) The address list is sorted by address and port now, instead of just
     address.  This allows multiple servers on the same host sitting on
     different ports.

Signed-off-by: David Howells <dhowells@redhat.com>
2017-11-13 15:38:19 +00:00

381 lines
8.4 KiB
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"
//#define AFS_MAX_ADDRESSES
// ((unsigned int)((PAGE_SIZE - sizeof(struct afs_addr_list)) /
// sizeof(struct sockaddr_rxrpc)))
#define AFS_MAX_ADDRESSES ((unsigned int)(sizeof(unsigned long) * 8))
/*
* 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);
alist = kzalloc(sizeof(*alist) + sizeof(alist->addrs[0]) * nr,
GFP_KERNEL);
if (!alist)
return NULL;
refcount_set(&alist->usage, 1);
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);
if (nr > AFS_MAX_ADDRESSES)
nr = AFS_MAX_ADDRESSES;
alist = afs_alloc_addrlist(nr, service, port);
if (!alist)
return ERR_PTR(-ENOMEM);
/* Extract the addresses */
p = text;
do {
struct sockaddr_rxrpc *srx = &alist->addrs[alist->nr_addrs];
char tdelim = delim;
if (*p == delim) {
p++;
continue;
}
if (*p == '[') {
p++;
tdelim = ']';
}
if (in4_pton(p, end - p,
(u8 *)&srx->transport.sin6.sin6_addr.s6_addr32[3],
tdelim, &p)) {
srx->transport.sin6.sin6_addr.s6_addr32[0] = 0;
srx->transport.sin6.sin6_addr.s6_addr32[1] = 0;
srx->transport.sin6.sin6_addr.s6_addr32[2] = htonl(0xffff);
} else if (in6_pton(p, end - p,
srx->transport.sin6.sin6_addr.s6_addr,
tdelim, &p)) {
/* Nothing to do */
} else {
goto bad_address;
}
if (tdelim == ']') {
if (p == end || *p != ']')
goto bad_address;
p++;
}
if (p < end) {
if (*p == '+') {
/* Port number specification "+1234" */
unsigned int 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));
srx->transport.sin6.sin6_port = htons(xport);
} else if (*p == delim) {
p++;
} else {
goto bad_address;
}
}
alist->nr_addrs++;
} while (p < end && alist->nr_addrs < AFS_MAX_ADDRESSES);
_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,
"ipv4", &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_in6 *a;
__be16 xport = htons(port);
int i;
for (i = 0; i < alist->nr_ipv4; i++) {
a = &alist->addrs[i].transport.sin6;
if (xdr == a->sin6_addr.s6_addr32[3] &&
xport == a->sin6_port)
return;
if (xdr == a->sin6_addr.s6_addr32[3] &&
xport < a->sin6_port)
break;
if (xdr < a->sin6_addr.s6_addr32[3])
break;
}
if (i < alist->nr_addrs)
memmove(alist->addrs + i + 1,
alist->addrs + i,
sizeof(alist->addrs[0]) * (alist->nr_addrs - i));
a = &alist->addrs[i].transport.sin6;
a->sin6_port = xport;
a->sin6_addr.s6_addr32[0] = 0;
a->sin6_addr.s6_addr32[1] = 0;
a->sin6_addr.s6_addr32[2] = htonl(0xffff);
a->sin6_addr.s6_addr32[3] = 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_in6 *a;
__be16 xport = htons(port);
int i, diff;
for (i = alist->nr_ipv4; i < alist->nr_addrs; i++) {
a = &alist->addrs[i].transport.sin6;
diff = memcmp(xdr, &a->sin6_addr, 16);
if (diff == 0 &&
xport == a->sin6_port)
return;
if (diff == 0 &&
xport < a->sin6_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));
a = &alist->addrs[i].transport.sin6;
a->sin6_port = xport;
a->sin6_addr.s6_addr32[0] = xdr[0];
a->sin6_addr.s6_addr32[1] = xdr[1];
a->sin6_addr.s6_addr32[2] = xdr[2];
a->sin6_addr.s6_addr32[3] = xdr[3];
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)
{
if (ac->responded && ac->index != ac->start)
WRITE_ONCE(ac->alist->index, ac->index);
afs_put_addrlist(ac->alist);
ac->alist = NULL;
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;
}