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-rw-r--r--fs/afs/addr_list.c308
1 files changed, 308 insertions, 0 deletions
diff --git a/fs/afs/addr_list.c b/fs/afs/addr_list.c
new file mode 100644
index 000000000000..ecb9c72aebd2
--- /dev/null
+++ b/fs/afs/addr_list.c
@@ -0,0 +1,308 @@
+/* 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)))
+
+/*
+ * 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;
+}
+
+/*
+ * 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;
+}