diff --git a/fs/afs/Makefile b/fs/afs/Makefile
index 924f02e9d7e7..75c4e4043d1d 100644
--- a/fs/afs/Makefile
+++ b/fs/afs/Makefile
@@ -31,6 +31,7 @@ kafs-y := \
server_list.o \
super.o \
vlclient.o \
+ vl_alias.o \
vl_list.o \
vl_probe.o \
vl_rotate.o \
diff --git a/fs/afs/cell.c b/fs/afs/cell.c
index 78ba5f932287..212098514ebf 100644
--- a/fs/afs/cell.c
+++ b/fs/afs/cell.c
@@ -164,6 +164,7 @@ static struct afs_cell *afs_alloc_cell(struct afs_net *net,
INIT_LIST_HEAD(&cell->proc_volumes);
rwlock_init(&cell->proc_lock);
rwlock_init(&cell->vl_servers_lock);
+ cell->flags = (1 << AFS_CELL_FL_CHECK_ALIAS);
/* Provide a VL server list, filling it in if we were given a list of
* addresses to use.
@@ -481,7 +482,9 @@ static void afs_cell_destroy(struct rcu_head *rcu)
ASSERTCMP(atomic_read(&cell->usage), ==, 0);
+ afs_put_volume(cell->net, cell->root_volume);
afs_put_vlserverlist(cell->net, rcu_access_pointer(cell->vl_servers));
+ afs_put_cell(cell->net, cell->alias_of);
key_put(cell->anonymous_key);
kfree(cell);
diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index 3606cfa50832..a3ef97d560ca 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -269,6 +269,7 @@ struct afs_net {
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;
@@ -342,8 +343,10 @@ enum afs_cell_state {
* 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 {
@@ -351,6 +354,8 @@ struct afs_cell {
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 */
@@ -363,6 +368,7 @@ struct afs_cell {
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 */
@@ -584,7 +590,7 @@ struct afs_volume {
#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 */
@@ -1376,6 +1382,11 @@ extern struct afs_call *afs_vl_get_capabilities(struct afs_net *, struct afs_add
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
*/
diff --git a/fs/afs/main.c b/fs/afs/main.c
index 56b52f8dbf15..9c79c91e8005 100644
--- a/fs/afs/main.c
+++ b/fs/afs/main.c
@@ -82,6 +82,7 @@ static int __net_init afs_net_init(struct net *net_ns)
INIT_WORK(&net->cells_manager, afs_manage_cells);
timer_setup(&net->cells_timer, afs_cells_timer, 0);
+ mutex_init(&net->cells_alias_lock);
mutex_init(&net->proc_cells_lock);
INIT_HLIST_HEAD(&net->proc_cells);
diff --git a/fs/afs/proc.c b/fs/afs/proc.c
index 1d21465a4108..256c3eff8c82 100644
--- a/fs/afs/proc.c
+++ b/fs/afs/proc.c
@@ -38,7 +38,7 @@ static int afs_proc_cells_show(struct seq_file *m, void *v)
if (v == SEQ_START_TOKEN) {
/* display header on line 1 */
- seq_puts(m, "USE TTL SV NAME\n");
+ seq_puts(m, "USE TTL SV ST NAME\n");
return 0;
}
@@ -46,10 +46,11 @@ static int afs_proc_cells_show(struct seq_file *m, void *v)
vllist = rcu_dereference(cell->vl_servers);
/* display one cell per line on subsequent lines */
- seq_printf(m, "%3u %6lld %2u %s\n",
+ seq_printf(m, "%3u %6lld %2u %2u %s\n",
atomic_read(&cell->usage),
cell->dns_expiry - ktime_get_real_seconds(),
vllist->nr_servers,
+ cell->state,
cell->name);
return 0;
}
diff --git a/fs/afs/rotate.c b/fs/afs/rotate.c
index 8c8dc2397c5d..d67b8c7eb3b9 100644
--- a/fs/afs/rotate.c
+++ b/fs/afs/rotate.c
@@ -25,7 +25,9 @@ static bool afs_start_fs_iteration(struct afs_operation *op,
int i;
read_lock(&op->volume->servers_lock);
- op->server_list = afs_get_serverlist(op->volume->servers);
+ op->server_list = afs_get_serverlist(
+ rcu_dereference_protected(op->volume->servers,
+ lockdep_is_held(&op->volume->servers_lock)));
read_unlock(&op->volume->servers_lock);
op->untried = (1UL << op->server_list->nr_servers) - 1;
@@ -173,7 +175,7 @@ bool afs_select_fileserver(struct afs_operation *op)
/* If the server list didn't change, then assume that
* it's the fileserver having trouble.
*/
- if (op->volume->servers == op->server_list) {
+ if (rcu_access_pointer(op->volume->servers) == op->server_list) {
op->error = -EREMOTEIO;
goto next_server;
}
@@ -263,7 +265,7 @@ bool afs_select_fileserver(struct afs_operation *op)
*
* TODO: Retry a few times with sleeps.
*/
- if (op->volume->servers == op->server_list) {
+ if (rcu_access_pointer(op->volume->servers) == op->server_list) {
op->error = -ENOMEDIUM;
goto failed;
}
diff --git a/fs/afs/super.c b/fs/afs/super.c
index c4bb314a22ae..aae6866ed209 100644
--- a/fs/afs/super.c
+++ b/fs/afs/super.c
@@ -352,7 +352,9 @@ static int afs_validate_fc(struct fs_context *fc)
{
struct afs_fs_context *ctx = fc->fs_private;
struct afs_volume *volume;
+ struct afs_cell *cell;
struct key *key;
+ int ret;
if (!ctx->dyn_root) {
if (ctx->no_cell) {
@@ -365,6 +367,7 @@ static int afs_validate_fc(struct fs_context *fc)
return -EDESTADDRREQ;
}
+ reget_key:
/* We try to do the mount securely. */
key = afs_request_key(ctx->cell);
if (IS_ERR(key))
@@ -377,6 +380,21 @@ static int afs_validate_fc(struct fs_context *fc)
ctx->volume = NULL;
}
+ if (test_bit(AFS_CELL_FL_CHECK_ALIAS, &ctx->cell->flags)) {
+ ret = afs_cell_detect_alias(ctx->cell, key);
+ if (ret < 0)
+ return ret;
+ if (ret == 1) {
+ _debug("switch to alias");
+ key_put(ctx->key);
+ ctx->key = NULL;
+ cell = afs_get_cell(ctx->cell->alias_of);
+ afs_put_cell(ctx->net, ctx->cell);
+ ctx->cell = cell;
+ goto reget_key;
+ }
+ }
+
volume = afs_create_volume(ctx);
if (IS_ERR(volume))
return PTR_ERR(volume);
@@ -518,7 +536,8 @@ static void afs_kill_super(struct super_block *sb)
* deactivating the superblock.
*/
if (as->volume)
- afs_clear_callback_interests(net, as->volume->servers);
+ afs_clear_callback_interests(
+ net, rcu_access_pointer(as->volume->servers));
kill_anon_super(sb);
if (as->volume)
afs_deactivate_volume(as->volume);
diff --git a/fs/afs/vl_alias.c b/fs/afs/vl_alias.c
new file mode 100644
index 000000000000..d1d91a25fbe0
--- /dev/null
+++ b/fs/afs/vl_alias.c
@@ -0,0 +1,235 @@
+// 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;
+}
diff --git a/fs/afs/volume.c b/fs/afs/volume.c
index 57d0509f7353..d4d9a8fbba3d 100644
--- a/fs/afs/volume.c
+++ b/fs/afs/volume.c
@@ -51,7 +51,7 @@ static struct afs_volume *afs_alloc_volume(struct afs_fs_context *params,
}
refcount_set(&slist->usage, 1);
- volume->servers = slist;
+ rcu_assign_pointer(volume->servers, slist);
return volume;
error_1:
@@ -156,7 +156,7 @@ static void afs_destroy_volume(struct afs_net *net, struct afs_volume *volume)
ASSERTCMP(volume->cache, ==, NULL);
#endif
- afs_put_serverlist(net, volume->servers);
+ afs_put_serverlist(net, rcu_access_pointer(volume->servers));
afs_put_cell(net, volume->cell);
kfree(volume);
@@ -256,10 +256,11 @@ static int afs_update_volume_status(struct afs_volume *volume, struct key *key)
write_lock(&volume->servers_lock);
discard = new;
- old = volume->servers;
+ old = rcu_dereference_protected(volume->servers,
+ lockdep_is_held(&volume->servers_lock));
if (afs_annotate_server_list(new, old)) {
new->seq = volume->servers_seq + 1;
- volume->servers = new;
+ rcu_assign_pointer(volume->servers, new);
smp_wmb();
volume->servers_seq++;
discard = old;