diff options
Diffstat (limited to 'fs/afs/addr_list.c')
| -rw-r--r-- | fs/afs/addr_list.c | 308 |
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; +} |