[PATCH 6.4 544/800] smb: client: fix shared DFS root mounts with different prefixes

Greg Kroah-Hartman
2023-07-16T20:18:16Z

From: Paulo Alcantara <pc@manguebit.com>

[ Upstream commit 3ae872de410751fe5e629e04da491a632d95201c ]

When having two DFS root mounts that are connected to same namespace,
same mount options but different prefix paths, we can't really use the
shared @server->origin_fullpath when chasing DFS links in them.

Move the origin_fullpath field to cifs_tcon structure so when having
shared DFS root mounts with different prefix paths, and we need to
chase any DFS links, dfs_get_automount_devname() will pick up the
correct full path out of the @tcon that will be used for the new
mount.

Before patch

mount.cifs //dom/dfs/dir /mnt/1 -o ...
mount.cifs //dom/dfs /mnt/2 -o ...
# shared server, ses, tcon
# server: origin_fullpath=//dom/dfs/dir

# @server->origin_fullpath + '/dir/link1'
$ ls /mnt/2/dir/link1
ls: cannot open directory '/mnt/2/dir/link1': No such file or directory

After patch

mount.cifs //dom/dfs/dir /mnt/1 -o ...
mount.cifs //dom/dfs /mnt/2 -o ...
# shared server & ses
# tcon_1: origin_fullpath=//dom/dfs/dir
# tcon_2: origin_fullpath=//dom/dfs

# @tcon_2->origin_fullpath + '/dir/link1'
$ ls /mnt/2/dir/link1
dir0 dir1 dir10 dir3 dir5 dir6 dir7 dir9 target2_file.txt tsub

Fixes: 8e3554150d6c ("cifs: fix sharing of DFS connections")
Signed-off-by: Paulo Alcantara (SUSE) <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/smb/client/cifs_debug.c | 16 +++++----
fs/smb/client/cifsglob.h | 10 +++---
fs/smb/client/cifsproto.h | 2 +-
fs/smb/client/connect.c | 70 ++++++++++++++++++++++----------------
fs/smb/client/dfs.c | 55 ++++++++++++------------------
fs/smb/client/dfs.h | 19 +++++------
fs/smb/client/dfs_cache.c | 8 +++--
fs/smb/client/misc.c | 38 ++++++++++++++++-----
8 files changed, 118 insertions(+), 100 deletions(-)

diff --git a/fs/smb/client/cifs_debug.c b/fs/smb/client/cifs_debug.c
index b279f745466e4..ed0f71137584f 100644
--- a/fs/smb/client/cifs_debug.c
+++ b/fs/smb/client/cifs_debug.c
@@ -122,6 +122,12 @@ static void cifs_debug_tcon(struct seq_file *m, struct cifs_tcon *tcon)
seq_puts(m, " nosparse");
if (tcon->need_reconnect)
seq_puts(m, "\tDISCONNECTED ");
+ spin_lock(&tcon->tc_lock);
+ if (tcon->origin_fullpath) {
+ seq_printf(m, "\n\tDFS origin fullpath: %s",
+ tcon->origin_fullpath);
+ }
+ spin_unlock(&tcon->tc_lock);
seq_putc(m, '\n');
}

@@ -427,13 +433,9 @@ static int cifs_debug_data_proc_show(struct seq_file *m, void *v)
seq_printf(m, "\nIn Send: %d In MaxReq Wait: %d",
atomic_read(&server->in_send),
atomic_read(&server->num_waiters));
- if (IS_ENABLED(CONFIG_CIFS_DFS_UPCALL)) {
- if (server->origin_fullpath)
- seq_printf(m, "\nDFS origin full path: %s",
- server->origin_fullpath);
- if (server->leaf_fullpath)
- seq_printf(m, "\nDFS leaf full path: %s",
- server->leaf_fullpath);
+ if (server->leaf_fullpath) {
+ seq_printf(m, "\nDFS leaf full path: %s",
+ server->leaf_fullpath);
}

seq_printf(m, "\n\n\tSessions: ");
diff --git a/fs/smb/client/cifsglob.h b/fs/smb/client/cifsglob.h
index b212a4e16b39b..ca2da713c5fe9 100644
--- a/fs/smb/client/cifsglob.h
+++ b/fs/smb/client/cifsglob.h
@@ -736,23 +736,20 @@ struct TCP_Server_Info {
#endif
struct mutex refpath_lock; /* protects leaf_fullpath */
/*
- * origin_fullpath: Canonical copy of smb3_fs_context::source.
- * It is used for matching existing DFS tcons.
- *
* leaf_fullpath: Canonical DFS referral path related to this
* connection.
* It is used in DFS cache refresher, reconnect and may
* change due to nested DFS links.
*
- * Both protected by @refpath_lock and @srv_lock. The @refpath_lock is
- * mosly used for not requiring a copy of @leaf_fullpath when getting
+ * Protected by @refpath_lock and @srv_lock. The @refpath_lock is
+ * mostly used for not requiring a copy of @leaf_fullpath when getting
* cached or new DFS referrals (which might also sleep during I/O).
* While @srv_lock is held for making string and NULL comparions against
* both fields as in mount(2) and cache refresh.
*
* format: \\HOST\SHARE[\OPTIONAL PATH]
*/
- char *origin_fullpath, *leaf_fullpath;
+ char *leaf_fullpath;
};

static inline bool is_smb1(struct TCP_Server_Info *server)
@@ -1205,6 +1202,7 @@ struct cifs_tcon {
struct delayed_work dfs_cache_work;
#endif
struct delayed_work query_interfaces; /* query interfaces workqueue job */
+ char *origin_fullpath; /* canonical copy of smb3_fs_context::source */
};

/*
diff --git a/fs/smb/client/cifsproto.h b/fs/smb/client/cifsproto.h
index d127aded2f287..94ab6402965c5 100644
--- a/fs/smb/client/cifsproto.h
+++ b/fs/smb/client/cifsproto.h
@@ -650,7 +650,7 @@ int smb2_parse_query_directory(struct cifs_tcon *tcon, struct kvec *rsp_iov,
int resp_buftype,
struct cifs_search_info *srch_inf);

-struct super_block *cifs_get_tcp_super(struct TCP_Server_Info *server);
+struct super_block *cifs_get_dfs_tcon_super(struct cifs_tcon *tcon);
void cifs_put_tcp_super(struct super_block *sb);
int cifs_update_super_prepath(struct cifs_sb_info *cifs_sb, char *prefix);
char *extract_hostname(const char *unc);
diff --git a/fs/smb/client/connect.c b/fs/smb/client/connect.c
index 9d16626e7a669..d9f0b3b94f007 100644
--- a/fs/smb/client/connect.c
+++ b/fs/smb/client/connect.c
@@ -996,7 +996,6 @@ static void clean_demultiplex_info(struct TCP_Server_Info *server)
*/
}

- kfree(server->origin_fullpath);
kfree(server->leaf_fullpath);
kfree(server);

@@ -1436,7 +1435,9 @@ match_security(struct TCP_Server_Info *server, struct smb3_fs_context *ctx)
}

/* this function must be called with srv_lock held */
-static int match_server(struct TCP_Server_Info *server, struct smb3_fs_context *ctx)
+static int match_server(struct TCP_Server_Info *server,
+ struct smb3_fs_context *ctx,
+ bool match_super)
{
struct sockaddr *addr = (struct sockaddr *)&ctx->dstaddr;

@@ -1467,36 +1468,38 @@ static int match_server(struct TCP_Server_Info *server, struct smb3_fs_context *
(struct sockaddr *)&server->srcaddr))
return 0;
/*
- * - Match for an DFS tcon (@server->origin_fullpath).
- * - Match for an DFS root server connection (@server->leaf_fullpath).
- * - If none of the above and @ctx->leaf_fullpath is set, then
- * it is a new DFS connection.
- * - If 'nodfs' mount option was passed, then match only connections
- * that have no DFS referrals set
- * (e.g. can't failover to other targets).
+ * When matching cifs.ko superblocks (@match_super == true), we can't
+ * really match either @server->leaf_fullpath or @server->dstaddr
+ * directly since this @server might belong to a completely different
+ * server -- in case of domain-based DFS referrals or DFS links -- as
+ * provided earlier by mount(2) through 'source' and 'ip' options.
+ *
+ * Otherwise, match the DFS referral in @server->leaf_fullpath or the
+ * destination address in @server->dstaddr.
+ *
+ * When using 'nodfs' mount option, we avoid sharing it with DFS
+ * connections as they might failover.
*/
- if (!ctx->nodfs) {
- if (ctx->source && server->origin_fullpath) {
- if (!dfs_src_pathname_equal(ctx->source,
- server->origin_fullpath))
+ if (!match_super) {
+ if (!ctx->nodfs) {
+ if (server->leaf_fullpath) {
+ if (!ctx->leaf_fullpath ||
+ strcasecmp(server->leaf_fullpath,
+ ctx->leaf_fullpath))
+ return 0;
+ } else if (ctx->leaf_fullpath) {
return 0;
+ }
} else if (server->leaf_fullpath) {
- if (!ctx->leaf_fullpath ||
- strcasecmp(server->leaf_fullpath,
- ctx->leaf_fullpath))
- return 0;
- } else if (ctx->leaf_fullpath) {
return 0;
}
- } else if (server->origin_fullpath || server->leaf_fullpath) {
- return 0;
}

/*
* Match for a regular connection (address/hostname/port) which has no
* DFS referrals set.
*/
- if (!server->origin_fullpath && !server->leaf_fullpath &&
+ if (!server->leaf_fullpath &&
(strcasecmp(server->hostname, ctx->server_hostname) ||
!match_server_address(server, addr) ||
!match_port(server, addr)))
@@ -1532,7 +1535,8 @@ cifs_find_tcp_session(struct smb3_fs_context *ctx)
* Skip ses channels since they're only handled in lower layers
* (e.g. cifs_send_recv).
*/
- if (CIFS_SERVER_IS_CHAN(server) || !match_server(server, ctx)) {
+ if (CIFS_SERVER_IS_CHAN(server) ||
+ !match_server(server, ctx, false)) {
spin_unlock(&server->srv_lock);
continue;
}
@@ -2320,10 +2324,16 @@ static int match_tcon(struct cifs_tcon *tcon, struct smb3_fs_context *ctx)

if (tcon->status == TID_EXITING)
return 0;
- /* Skip UNC validation when matching DFS connections or superblocks */
- if (!server->origin_fullpath && !server->leaf_fullpath &&
- strncmp(tcon->tree_name, ctx->UNC, MAX_TREE_SIZE))
+
+ if (tcon->origin_fullpath) {
+ if (!ctx->source ||
+ !dfs_src_pathname_equal(ctx->source,
+ tcon->origin_fullpath))
+ return 0;
+ } else if (!server->leaf_fullpath &&
+ strncmp(tcon->tree_name, ctx->UNC, MAX_TREE_SIZE)) {
return 0;
+ }
if (tcon->seal != ctx->seal)
return 0;
if (tcon->snapshot_time != ctx->snapshot_time)
@@ -2722,7 +2732,7 @@ compare_mount_options(struct super_block *sb, struct cifs_mnt_data *mnt_data)
}

static int match_prepath(struct super_block *sb,
- struct TCP_Server_Info *server,
+ struct cifs_tcon *tcon,
struct cifs_mnt_data *mnt_data)
{
struct smb3_fs_context *ctx = mnt_data->ctx;
@@ -2733,8 +2743,8 @@ static int match_prepath(struct super_block *sb,
bool new_set = (new->mnt_cifs_flags & CIFS_MOUNT_USE_PREFIX_PATH) &&
new->prepath;

- if (server->origin_fullpath &&
- dfs_src_pathname_equal(server->origin_fullpath, ctx->source))
+ if (tcon->origin_fullpath &&
+ dfs_src_pathname_equal(tcon->origin_fullpath, ctx->source))
return 1;

if (old_set && new_set && !strcmp(new->prepath, old->prepath))
@@ -2782,10 +2792,10 @@ cifs_match_super(struct super_block *sb, void *data)
spin_lock(&ses->ses_lock);
spin_lock(&ses->chan_lock);
spin_lock(&tcon->tc_lock);
- if (!match_server(tcp_srv, ctx) ||
+ if (!match_server(tcp_srv, ctx, true) ||
!match_session(ses, ctx) ||
!match_tcon(tcon, ctx) ||
- !match_prepath(sb, tcp_srv, mnt_data)) {
+ !match_prepath(sb, tcon, mnt_data)) {
rc = 0;
goto out;
}
diff --git a/fs/smb/client/dfs.c b/fs/smb/client/dfs.c
index 2390b2fedd6a3..267536a7531df 100644
--- a/fs/smb/client/dfs.c
+++ b/fs/smb/client/dfs.c
@@ -249,14 +249,12 @@ static int __dfs_mount_share(struct cifs_mount_ctx *mnt_ctx)
server = mnt_ctx->server;
tcon = mnt_ctx->tcon;

- mutex_lock(&server->refpath_lock);
- spin_lock(&server->srv_lock);
- if (!server->origin_fullpath) {
- server->origin_fullpath = origin_fullpath;
+ spin_lock(&tcon->tc_lock);
+ if (!tcon->origin_fullpath) {
+ tcon->origin_fullpath = origin_fullpath;
origin_fullpath = NULL;
}
- spin_unlock(&server->srv_lock);
- mutex_unlock(&server->refpath_lock);
+ spin_unlock(&tcon->tc_lock);

if (list_empty(&tcon->dfs_ses_list)) {
list_replace_init(&mnt_ctx->dfs_ses_list,
@@ -279,18 +277,13 @@ int dfs_mount_share(struct cifs_mount_ctx *mnt_ctx, bool *isdfs)
{
struct smb3_fs_context *ctx = mnt_ctx->fs_ctx;
struct cifs_ses *ses;
- char *source = ctx->source;
bool nodfs = ctx->nodfs;
int rc;

*isdfs = false;
- /* Temporarily set @ctx->source to NULL as we're not matching DFS
- * superblocks yet. See cifs_match_super() and match_server().
- */
- ctx->source = NULL;
rc = get_session(mnt_ctx, NULL);
if (rc)
- goto out;
+ return rc;

ctx->dfs_root_ses = mnt_ctx->ses;
/*
@@ -304,7 +297,7 @@ int dfs_mount_share(struct cifs_mount_ctx *mnt_ctx, bool *isdfs)
rc = dfs_get_referral(mnt_ctx, ctx->UNC + 1, NULL, NULL);
if (rc) {
if (rc != -ENOENT && rc != -EOPNOTSUPP && rc != -EIO)
- goto out;
+ return rc;
nodfs = true;
}
}
@@ -312,7 +305,7 @@ int dfs_mount_share(struct cifs_mount_ctx *mnt_ctx, bool *isdfs)
rc = cifs_mount_get_tcon(mnt_ctx);
if (!rc)
rc = cifs_is_path_remote(mnt_ctx);
- goto out;
+ return rc;
}

*isdfs = true;
@@ -328,12 +321,7 @@ int dfs_mount_share(struct cifs_mount_ctx *mnt_ctx, bool *isdfs)
rc = __dfs_mount_share(mnt_ctx);
if (ses == ctx->dfs_root_ses)
cifs_put_smb_ses(ses);
-out:
- /*
- * Restore previous value of @ctx->source so DFS superblock can be
- * matched in cifs_match_super().
- */
- ctx->source = source;
+
return rc;
}

@@ -567,11 +555,11 @@ int cifs_tree_connect(const unsigned int xid, struct cifs_tcon *tcon, const stru
int rc;
struct TCP_Server_Info *server = tcon->ses->server;
const struct smb_version_operations *ops = server->ops;
- struct super_block *sb = NULL;
- struct cifs_sb_info *cifs_sb;
struct dfs_cache_tgt_list tl = DFS_CACHE_TGT_LIST_INIT(tl);
- char *tree;
+ struct cifs_sb_info *cifs_sb = NULL;
+ struct super_block *sb = NULL;
struct dfs_info3_param ref = {0};
+ char *tree;

/* only send once per connect */
spin_lock(&tcon->tc_lock);
@@ -603,19 +591,18 @@ int cifs_tree_connect(const unsigned int xid, struct cifs_tcon *tcon, const stru
goto out;
}

- sb = cifs_get_tcp_super(server);
- if (IS_ERR(sb)) {
- rc = PTR_ERR(sb);
- cifs_dbg(VFS, "%s: could not find superblock: %d\n", __func__, rc);
- goto out;
- }
-
- cifs_sb = CIFS_SB(sb);
+ sb = cifs_get_dfs_tcon_super(tcon);
+ if (!IS_ERR(sb))
+ cifs_sb = CIFS_SB(sb);

- /* If it is not dfs or there was no cached dfs referral, then reconnect to same share */
- if (!server->leaf_fullpath ||
+ /*
+ * Tree connect to last share in @tcon->tree_name whether dfs super or
+ * cached dfs referral was not found.
+ */
+ if (!cifs_sb || !server->leaf_fullpath ||
dfs_cache_noreq_find(server->leaf_fullpath + 1, &ref, &tl)) {
- rc = ops->tree_connect(xid, tcon->ses, tcon->tree_name, tcon, cifs_sb->local_nls);
+ rc = ops->tree_connect(xid, tcon->ses, tcon->tree_name, tcon,
+ cifs_sb ? cifs_sb->local_nls : nlsc);
goto out;
}

diff --git a/fs/smb/client/dfs.h b/fs/smb/client/dfs.h
index 1c90df5ecfbda..98e9d2aca6a7a 100644
--- a/fs/smb/client/dfs.h
+++ b/fs/smb/client/dfs.h
@@ -39,16 +39,15 @@ static inline char *dfs_get_automount_devname(struct dentry *dentry, void *page)
{
struct cifs_sb_info *cifs_sb = CIFS_SB(dentry->d_sb);
struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);
- struct TCP_Server_Info *server = tcon->ses->server;
size_t len;
char *s;

- spin_lock(&server->srv_lock);
- if (unlikely(!server->origin_fullpath)) {
- spin_unlock(&server->srv_lock);
+ spin_lock(&tcon->tc_lock);
+ if (unlikely(!tcon->origin_fullpath)) {
+ spin_unlock(&tcon->tc_lock);
return ERR_PTR(-EREMOTE);
}
- spin_unlock(&server->srv_lock);
+ spin_unlock(&tcon->tc_lock);

s = dentry_path_raw(dentry, page, PATH_MAX);
if (IS_ERR(s))
@@ -57,16 +56,16 @@ static inline char *dfs_get_automount_devname(struct dentry *dentry, void *page)
if (!s[1])
s++;

- spin_lock(&server->srv_lock);
- len = strlen(server->origin_fullpath);
+ spin_lock(&tcon->tc_lock);
+ len = strlen(tcon->origin_fullpath);
if (s < (char *)page + len) {
- spin_unlock(&server->srv_lock);
+ spin_unlock(&tcon->tc_lock);
return ERR_PTR(-ENAMETOOLONG);
}

s -= len;
- memcpy(s, server->origin_fullpath, len);
- spin_unlock(&server->srv_lock);
+ memcpy(s, tcon->origin_fullpath, len);
+ spin_unlock(&tcon->tc_lock);
convert_delimiter(s, '/');

return s;
diff --git a/fs/smb/client/dfs_cache.c b/fs/smb/client/dfs_cache.c
index 1513b2709889b..33adf43a01f1d 100644
--- a/fs/smb/client/dfs_cache.c
+++ b/fs/smb/client/dfs_cache.c
@@ -1248,18 +1248,20 @@ static int refresh_tcon(struct cifs_tcon *tcon, bool force_refresh)
int dfs_cache_remount_fs(struct cifs_sb_info *cifs_sb)
{
struct cifs_tcon *tcon;
- struct TCP_Server_Info *server;

if (!cifs_sb || !cifs_sb->master_tlink)
return -EINVAL;

tcon = cifs_sb_master_tcon(cifs_sb);
- server = tcon->ses->server;

- if (!server->origin_fullpath) {
+ spin_lock(&tcon->tc_lock);
+ if (!tcon->origin_fullpath) {
+ spin_unlock(&tcon->tc_lock);
cifs_dbg(FYI, "%s: not a dfs mount\n", __func__);
return 0;
}
+ spin_unlock(&tcon->tc_lock);
+
/*
* After reconnecting to a different server, unique ids won't match anymore, so we disable
* serverino. This prevents dentry revalidation to think the dentry are stale (ESTALE).
diff --git a/fs/smb/client/misc.c b/fs/smb/client/misc.c
index cd914be905b24..b0dedc26643b6 100644
--- a/fs/smb/client/misc.c
+++ b/fs/smb/client/misc.c
@@ -156,6 +156,7 @@ tconInfoFree(struct cifs_tcon *tcon)
#ifdef CONFIG_CIFS_DFS_UPCALL
dfs_put_root_smb_sessions(&tcon->dfs_ses_list);
#endif
+ kfree(tcon->origin_fullpath);
kfree(tcon);
}

@@ -1106,20 +1107,25 @@ struct super_cb_data {
struct super_block *sb;
};

-static void tcp_super_cb(struct super_block *sb, void *arg)
+static void tcon_super_cb(struct super_block *sb, void *arg)
{
struct super_cb_data *sd = arg;
- struct TCP_Server_Info *server = sd->data;
struct cifs_sb_info *cifs_sb;
- struct cifs_tcon *tcon;
+ struct cifs_tcon *t1 = sd->data, *t2;

if (sd->sb)
return;

cifs_sb = CIFS_SB(sb);
- tcon = cifs_sb_master_tcon(cifs_sb);
- if (tcon->ses->server == server)
+ t2 = cifs_sb_master_tcon(cifs_sb);
+
+ spin_lock(&t2->tc_lock);
+ if (t1->ses == t2->ses &&
+ t1->ses->server == t2->ses->server &&
+ t2->origin_fullpath &&
+ dfs_src_pathname_equal(t2->origin_fullpath, t1->origin_fullpath))
sd->sb = sb;
+ spin_unlock(&t2->tc_lock);
}

static struct super_block *__cifs_get_super(void (*f)(struct super_block *, void *),
@@ -1145,6 +1151,7 @@ static struct super_block *__cifs_get_super(void (*f)(struct super_block *, void
return sd.sb;
}
}
+ pr_warn_once("%s: could not find dfs superblock\n", __func__);
return ERR_PTR(-EINVAL);
}

@@ -1154,9 +1161,15 @@ static void __cifs_put_super(struct super_block *sb)
cifs_sb_deactive(sb);
}

-struct super_block *cifs_get_tcp_super(struct TCP_Server_Info *server)
+struct super_block *cifs_get_dfs_tcon_super(struct cifs_tcon *tcon)
{
- return __cifs_get_super(tcp_super_cb, server);
+ spin_lock(&tcon->tc_lock);
+ if (!tcon->origin_fullpath) {
+ spin_unlock(&tcon->tc_lock);
+ return ERR_PTR(-ENOENT);
+ }
+ spin_unlock(&tcon->tc_lock);
+ return __cifs_get_super(tcon_super_cb, tcon);
}

void cifs_put_tcp_super(struct super_block *sb)
@@ -1238,9 +1251,16 @@ int cifs_inval_name_dfs_link_error(const unsigned int xid,
*/
if (strlen(full_path) < 2 || !cifs_sb ||
(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_DFS) ||
- !is_tcon_dfs(tcon) || !ses->server->origin_fullpath)
+ !is_tcon_dfs(tcon))
return 0;

+ spin_lock(&tcon->tc_lock);
+ if (!tcon->origin_fullpath) {
+ spin_unlock(&tcon->tc_lock);
+ return 0;
+ }
+ spin_unlock(&tcon->tc_lock);
+
/*
* Slow path - tcon is DFS and @full_path has prefix path, so attempt
* to get a referral to figure out whether it is an DFS link.
@@ -1264,7 +1284,7 @@ int cifs_inval_name_dfs_link_error(const unsigned int xid,

/*
* XXX: we are not using dfs_cache_find() here because we might
- * end filling all the DFS cache and thus potentially
+ * end up filling all the DFS cache and thus potentially
* removing cached DFS targets that the client would eventually
* need during failover.
*/
--
2.39.2