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-rw-r--r--fs/afs/vl_alias.c383
1 files changed, 383 insertions, 0 deletions
diff --git a/fs/afs/vl_alias.c b/fs/afs/vl_alias.c
new file mode 100644
index 0000000000..f04a80e4f5
--- /dev/null
+++ b/fs/afs/vl_alias.c
@@ -0,0 +1,383 @@
+// 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(" = %p", 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:
+ WARN_ON(1);
+ diff = 1;
+ }
+
+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_use_cell(p, afs_cell_trace_use_alias);
+ return 1;
+}
+
+/*
+ * Query the new cell for a volume from a cell we're already using.
+ */
+static int afs_query_for_alias_one(struct afs_cell *cell, struct key *key,
+ struct afs_cell *p)
+{
+ struct afs_volume *volume, *pvol = NULL;
+ int ret;
+
+ /* Arbitrarily pick a volume from the list. */
+ read_seqlock_excl(&p->volume_lock);
+ if (!RB_EMPTY_ROOT(&p->volumes))
+ pvol = afs_get_volume(rb_entry(p->volumes.rb_node,
+ struct afs_volume, cell_node),
+ afs_volume_trace_get_query_alias);
+ read_sequnlock_excl(&p->volume_lock);
+ if (!pvol)
+ return 0;
+
+ _enter("%s:%s", cell->name, pvol->name);
+
+ /* And see if it's in the new cell. */
+ volume = afs_sample_volume(cell, key, pvol->name, pvol->name_len);
+ if (IS_ERR(volume)) {
+ afs_put_volume(cell->net, pvol, afs_volume_trace_put_query_alias);
+ if (PTR_ERR(volume) != -ENOMEDIUM)
+ return PTR_ERR(volume);
+ /* That volume is not in the new cell, so not an alias */
+ return 0;
+ }
+
+ /* The new cell has a like-named volume also - compare volume ID,
+ * server and address lists.
+ */
+ ret = 0;
+ if (pvol->vid == volume->vid) {
+ rcu_read_lock();
+ if (afs_compare_volume_slists(volume, pvol))
+ ret = 1;
+ rcu_read_unlock();
+ }
+
+ afs_put_volume(cell->net, volume, afs_volume_trace_put_query_alias);
+ afs_put_volume(cell->net, pvol, afs_volume_trace_put_query_alias);
+ return ret;
+}
+
+/*
+ * Query the new cell for volumes we know exist in cells we're already using.
+ */
+static int afs_query_for_alias(struct afs_cell *cell, struct key *key)
+{
+ struct afs_cell *p;
+
+ _enter("%s", cell->name);
+
+ if (mutex_lock_interruptible(&cell->net->proc_cells_lock) < 0)
+ return -ERESTARTSYS;
+
+ hlist_for_each_entry(p, &cell->net->proc_cells, proc_link) {
+ if (p == cell || p->alias_of)
+ continue;
+ if (RB_EMPTY_ROOT(&p->volumes))
+ continue;
+ if (p->root_volume)
+ continue; /* Ignore cells that have a root.cell volume. */
+ afs_use_cell(p, afs_cell_trace_use_check_alias);
+ mutex_unlock(&cell->net->proc_cells_lock);
+
+ if (afs_query_for_alias_one(cell, key, p) != 0)
+ goto is_alias;
+
+ if (mutex_lock_interruptible(&cell->net->proc_cells_lock) < 0) {
+ afs_unuse_cell(cell->net, p, afs_cell_trace_unuse_check_alias);
+ return -ERESTARTSYS;
+ }
+
+ afs_unuse_cell(cell->net, p, afs_cell_trace_unuse_check_alias);
+ }
+
+ mutex_unlock(&cell->net->proc_cells_lock);
+ _leave(" = 0");
+ return 0;
+
+is_alias:
+ cell->alias_of = p; /* Transfer our ref */
+ return 1;
+}
+
+/*
+ * Look up a VLDB record for a volume.
+ */
+static char *afs_vl_get_cell_name(struct afs_cell *cell, struct key *key)
+{
+ struct afs_vl_cursor vc;
+ char *cell_name = ERR_PTR(-EDESTADDRREQ);
+ bool skipped = false, not_skipped = false;
+ int ret;
+
+ if (!afs_begin_vlserver_operation(&vc, cell, key))
+ return ERR_PTR(-ERESTARTSYS);
+
+ while (afs_select_vlserver(&vc)) {
+ if (!test_bit(AFS_VLSERVER_FL_IS_YFS, &vc.server->flags)) {
+ vc.ac.error = -EOPNOTSUPP;
+ skipped = true;
+ continue;
+ }
+ not_skipped = true;
+ cell_name = afs_yfsvl_get_cell_name(&vc);
+ }
+
+ ret = afs_end_vlserver_operation(&vc);
+ if (skipped && !not_skipped)
+ ret = -EOPNOTSUPP;
+ return ret < 0 ? ERR_PTR(ret) : cell_name;
+}
+
+static int yfs_check_canonical_cell_name(struct afs_cell *cell, struct key *key)
+{
+ struct afs_cell *master;
+ char *cell_name;
+
+ cell_name = afs_vl_get_cell_name(cell, key);
+ if (IS_ERR(cell_name))
+ return PTR_ERR(cell_name);
+
+ if (strcmp(cell_name, cell->name) == 0) {
+ kfree(cell_name);
+ return 0;
+ }
+
+ master = afs_lookup_cell(cell->net, cell_name, strlen(cell_name),
+ NULL, false);
+ kfree(cell_name);
+ if (IS_ERR(master))
+ return PTR_ERR(master);
+
+ cell->alias_of = master; /* Transfer our ref */
+ return 1;
+}
+
+static int afs_do_cell_detect_alias(struct afs_cell *cell, struct key *key)
+{
+ struct afs_volume *root_volume;
+ int ret;
+
+ _enter("%s", cell->name);
+
+ ret = yfs_check_canonical_cell_name(cell, key);
+ if (ret != -EOPNOTSUPP)
+ return ret;
+
+ /* 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 afs_query_for_alias(cell, key);
+}
+
+/*
+ * 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;
+}