struct timer_list cells_timer;
atomic_t cells_outstanding;
seqlock_t cells_lock;
+ struct mutex cells_alias_lock;
struct mutex proc_cells_lock;
struct hlist_head proc_cells;
* for authentication and encryption. The cell name is not typically used in
* the protocol.
*
- * There is no easy way to determine if two cells are aliases or one is a
- * subset of another.
+ * Two cells are determined to be aliases if they have an explicit alias (YFS
+ * only), share any VL servers in common or have at least one volume in common.
+ * "In common" means that the address list of the VL servers or the fileservers
+ * share at least one endpoint.
*/
struct afs_cell {
union {
struct rb_node net_node; /* Node in net->cells */
};
struct afs_net *net;
+ struct afs_cell *alias_of; /* The cell this is an alias of */
+ struct afs_volume *root_volume; /* The root.cell volume if there is one */
struct key *anonymous_key; /* anonymous user key for this cell */
struct work_struct manager; /* Manager for init/deinit/dns */
struct hlist_node proc_link; /* /proc cell list link */
unsigned long flags;
#define AFS_CELL_FL_NO_GC 0 /* The cell was added manually, don't auto-gc */
#define AFS_CELL_FL_DO_LOOKUP 1 /* DNS lookup requested */
+#define AFS_CELL_FL_CHECK_ALIAS 2 /* Need to check for aliases */
enum afs_cell_state state;
short error;
enum dns_record_source dns_source:8; /* Latest source of data from lookup */
#ifdef CONFIG_AFS_FSCACHE
struct fscache_cookie *cache; /* caching cookie */
#endif
- struct afs_server_list *servers; /* List of servers on which volume resides */
+ struct afs_server_list __rcu *servers; /* List of servers on which volume resides */
rwlock_t servers_lock; /* Lock for ->servers */
unsigned int servers_seq; /* Incremented each time ->servers changes */
extern struct afs_addr_list *afs_yfsvl_get_endpoints(struct afs_vl_cursor *, const uuid_t *);
extern char *afs_yfsvl_get_cell_name(struct afs_vl_cursor *);
+/*
+ * vl_alias.c
+ */
+extern int afs_cell_detect_alias(struct afs_cell *, struct key *);
+
/*
* vl_probe.c
*/
--- /dev/null
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* AFS cell alias detection
+ *
+ * Copyright (C) 2020 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include <linux/namei.h>
+#include <keys/rxrpc-type.h>
+#include "internal.h"
+
+/*
+ * Sample a volume.
+ */
+static struct afs_volume *afs_sample_volume(struct afs_cell *cell, struct key *key,
+ const char *name, unsigned int namelen)
+{
+ struct afs_volume *volume;
+ struct afs_fs_context fc = {
+ .type = 0, /* Explicitly leave it to the VLDB */
+ .volnamesz = namelen,
+ .volname = name,
+ .net = cell->net,
+ .cell = cell,
+ .key = key, /* This might need to be something */
+ };
+
+ volume = afs_create_volume(&fc);
+ _leave(" = %px", volume);
+ return volume;
+}
+
+/*
+ * Compare two addresses.
+ */
+static int afs_compare_addrs(const struct sockaddr_rxrpc *srx_a,
+ const struct sockaddr_rxrpc *srx_b)
+{
+ short port_a, port_b;
+ int addr_a, addr_b, diff;
+
+ diff = (short)srx_a->transport_type - (short)srx_b->transport_type;
+ if (diff)
+ goto out;
+
+ switch (srx_a->transport_type) {
+ case AF_INET: {
+ const struct sockaddr_in *a = &srx_a->transport.sin;
+ const struct sockaddr_in *b = &srx_b->transport.sin;
+ addr_a = ntohl(a->sin_addr.s_addr);
+ addr_b = ntohl(b->sin_addr.s_addr);
+ diff = addr_a - addr_b;
+ if (diff == 0) {
+ port_a = ntohs(a->sin_port);
+ port_b = ntohs(b->sin_port);
+ diff = port_a - port_b;
+ }
+ break;
+ }
+
+ case AF_INET6: {
+ const struct sockaddr_in6 *a = &srx_a->transport.sin6;
+ const struct sockaddr_in6 *b = &srx_b->transport.sin6;
+ diff = memcmp(&a->sin6_addr, &b->sin6_addr, 16);
+ if (diff == 0) {
+ port_a = ntohs(a->sin6_port);
+ port_b = ntohs(b->sin6_port);
+ diff = port_a - port_b;
+ }
+ break;
+ }
+
+ default:
+ BUG();
+ }
+
+out:
+ return diff;
+}
+
+/*
+ * Compare the address lists of a pair of fileservers.
+ */
+static int afs_compare_fs_alists(const struct afs_server *server_a,
+ const struct afs_server *server_b)
+{
+ const struct afs_addr_list *la, *lb;
+ int a = 0, b = 0, addr_matches = 0;
+
+ la = rcu_dereference(server_a->addresses);
+ lb = rcu_dereference(server_b->addresses);
+
+ while (a < la->nr_addrs && b < lb->nr_addrs) {
+ const struct sockaddr_rxrpc *srx_a = &la->addrs[a];
+ const struct sockaddr_rxrpc *srx_b = &lb->addrs[b];
+ int diff = afs_compare_addrs(srx_a, srx_b);
+
+ if (diff < 0) {
+ a++;
+ } else if (diff > 0) {
+ b++;
+ } else {
+ addr_matches++;
+ a++;
+ b++;
+ }
+ }
+
+ return addr_matches;
+}
+
+/*
+ * Compare the fileserver lists of two volumes. The server lists are sorted in
+ * order of ascending UUID.
+ */
+static int afs_compare_volume_slists(const struct afs_volume *vol_a,
+ const struct afs_volume *vol_b)
+{
+ const struct afs_server_list *la, *lb;
+ int i, a = 0, b = 0, uuid_matches = 0, addr_matches = 0;
+
+ la = rcu_dereference(vol_a->servers);
+ lb = rcu_dereference(vol_b->servers);
+
+ for (i = 0; i < AFS_MAXTYPES; i++)
+ if (la->vids[i] != lb->vids[i])
+ return 0;
+
+ while (a < la->nr_servers && b < lb->nr_servers) {
+ const struct afs_server *server_a = la->servers[a].server;
+ const struct afs_server *server_b = lb->servers[b].server;
+ int diff = memcmp(&server_a->uuid, &server_b->uuid, sizeof(uuid_t));
+
+ if (diff < 0) {
+ a++;
+ } else if (diff > 0) {
+ b++;
+ } else {
+ uuid_matches++;
+ addr_matches += afs_compare_fs_alists(server_a, server_b);
+ a++;
+ b++;
+ }
+ }
+
+ _leave(" = %d [um %d]", addr_matches, uuid_matches);
+ return addr_matches;
+}
+
+/*
+ * Compare root.cell volumes.
+ */
+static int afs_compare_cell_roots(struct afs_cell *cell)
+{
+ struct afs_cell *p;
+
+ _enter("");
+
+ rcu_read_lock();
+
+ hlist_for_each_entry_rcu(p, &cell->net->proc_cells, proc_link) {
+ if (p == cell || p->alias_of)
+ continue;
+ if (!p->root_volume)
+ continue; /* Ignore cells that don't have a root.cell volume. */
+
+ if (afs_compare_volume_slists(cell->root_volume, p->root_volume) != 0)
+ goto is_alias;
+ }
+
+ rcu_read_unlock();
+ _leave(" = 0");
+ return 0;
+
+is_alias:
+ rcu_read_unlock();
+ cell->alias_of = afs_get_cell(p);
+ return 1;
+}
+
+static int afs_do_cell_detect_alias(struct afs_cell *cell, struct key *key)
+{
+ struct afs_volume *root_volume;
+
+ _enter("%s", cell->name);
+
+ /* Try and get the root.cell volume for comparison with other cells */
+ root_volume = afs_sample_volume(cell, key, "root.cell", 9);
+ if (!IS_ERR(root_volume)) {
+ cell->root_volume = root_volume;
+ return afs_compare_cell_roots(cell);
+ }
+
+ if (PTR_ERR(root_volume) != -ENOMEDIUM)
+ return PTR_ERR(root_volume);
+
+ /* Okay, this cell doesn't have an root.cell volume. We need to
+ * locate some other random volume and use that to check.
+ */
+ return -ENOMEDIUM;
+}
+
+/*
+ * Check to see if a new cell is an alias of a cell we already have. At this
+ * point we have the cell's volume server list.
+ *
+ * Returns 0 if we didn't detect an alias, 1 if we found an alias and an error
+ * if we had problems gathering the data required. In the case the we did
+ * detect an alias, cell->alias_of is set to point to the assumed master.
+ */
+int afs_cell_detect_alias(struct afs_cell *cell, struct key *key)
+{
+ struct afs_net *net = cell->net;
+ int ret;
+
+ if (mutex_lock_interruptible(&net->cells_alias_lock) < 0)
+ return -ERESTARTSYS;
+
+ if (test_bit(AFS_CELL_FL_CHECK_ALIAS, &cell->flags)) {
+ ret = afs_do_cell_detect_alias(cell, key);
+ if (ret >= 0)
+ clear_bit_unlock(AFS_CELL_FL_CHECK_ALIAS, &cell->flags);
+ } else {
+ ret = cell->alias_of ? 1 : 0;
+ }
+
+ mutex_unlock(&net->cells_alias_lock);
+
+ if (ret == 1)
+ pr_notice("kAFS: Cell %s is an alias of %s\n",
+ cell->name, cell->alias_of->name);
+ return ret;
+}
projects / linux.git / commitdiff