The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x bc962159e8e326af634a506508034a375bf2b858 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '168000344359180@kroah.com' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

bc962159e8e3 ("cifs: avoid race conditions with parallel reconnects") 1bcd548d935a ("cifs: prevent data race in cifs_reconnect_tcon()") e77978de4765 ("cifs: update ip_addr for ses only for primary chan setup") 3c0070f54b31 ("cifs: prevent data race in smb2_reconnect()") 25cf01b7c920 ("cifs: set correct status of tcon ipc when reconnecting") d7d7a66aacd6 ("cifs: avoid use of global locks for high contention data") 9543c8ab3016 ("cifs: list_for_each() -> list_for_each_entry()") af3a6d1018f0 ("cifs: update cifs_ses::ip_addr after failover") b54034a73baf ("cifs: during reconnect, update interface if necessary") cc391b694ff0 ("cifs: fix potential deadlock in direct reclaim") 5752bf645f9d ("cifs: avoid parallel session setups on same channel") dd3cd8709ed5 ("cifs: use new enum for ses_status") 1a6a41d4cedd ("cifs: do not use tcpStatus after negotiate completes") cd70a3e8988a ("cifs: use correct lock type in cifs_reconnect()") fb39d30e2272 ("cifs: force new session setup and tcon for dfs") 9a005bea4f59 ("Merge tag '5.18-smb3-fixes-part2' of git://git.samba.org/sfrench/cifs-2.6")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From bc962159e8e326af634a506508034a375bf2b858 Mon Sep 17 00:00:00 2001 From: Shyam Prasad N sprasad@microsoft.com Date: Mon, 20 Mar 2023 06:08:19 +0000 Subject: [PATCH] cifs: avoid race conditions with parallel reconnects

When multiple processes/channels do reconnects in parallel we used to return success immediately negotiate/session-setup/tree-connect, causing race conditions between processes that enter the function in parallel. This caused several errors related to session not found to show up during parallel reconnects.

Signed-off-by: Shyam Prasad N sprasad@microsoft.com Reviewed-by: Paulo Alcantara (SUSE) pc@manguebit.com Cc: stable@vger.kernel.org Signed-off-by: Steve French stfrench@microsoft.com

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c index f42cc7077312..c3162ef9c9e9 100644 --- a/fs/cifs/connect.c +++ b/fs/cifs/connect.c @@ -212,31 +212,42 @@ cifs_mark_tcp_ses_conns_for_reconnect(struct TCP_Server_Info *server, cifs_chan_update_iface(ses, server);

spin_lock(&ses->chan_lock); - if (!mark_smb_session && cifs_chan_needs_reconnect(ses, server)) - goto next_session; + if (!mark_smb_session && cifs_chan_needs_reconnect(ses, server)) { + spin_unlock(&ses->chan_lock); + continue; + }

if (mark_smb_session) CIFS_SET_ALL_CHANS_NEED_RECONNECT(ses); else cifs_chan_set_need_reconnect(ses, server);

+ cifs_dbg(FYI, "%s: channel connect bitmap: 0x%lx\n", + __func__, ses->chans_need_reconnect); + /* If all channels need reconnect, then tcon needs reconnect */ - if (!mark_smb_session && !CIFS_ALL_CHANS_NEED_RECONNECT(ses)) - goto next_session; + if (!mark_smb_session && !CIFS_ALL_CHANS_NEED_RECONNECT(ses)) { + spin_unlock(&ses->chan_lock); + continue; + } + spin_unlock(&ses->chan_lock);

+ spin_lock(&ses->ses_lock); ses->ses_status = SES_NEED_RECON; + spin_unlock(&ses->ses_lock);

list_for_each_entry(tcon, &ses->tcon_list, tcon_list) { tcon->need_reconnect = true; + spin_lock(&tcon->tc_lock); tcon->status = TID_NEED_RECON; + spin_unlock(&tcon->tc_lock); } if (ses->tcon_ipc) { ses->tcon_ipc->need_reconnect = true; + spin_lock(&ses->tcon_ipc->tc_lock); ses->tcon_ipc->status = TID_NEED_RECON; + spin_unlock(&ses->tcon_ipc->tc_lock); } - -next_session: - spin_unlock(&ses->chan_lock); } spin_unlock(&cifs_tcp_ses_lock); } @@ -3653,11 +3664,19 @@ cifs_negotiate_protocol(const unsigned int xid, struct cifs_ses *ses,

/* only send once per connect */ spin_lock(&server->srv_lock); - if (!server->ops->need_neg(server) || + if (server->tcpStatus != CifsGood && + server->tcpStatus != CifsNew && server->tcpStatus != CifsNeedNegotiate) { + spin_unlock(&server->srv_lock); + return -EHOSTDOWN; + } + + if (!server->ops->need_neg(server) && + server->tcpStatus == CifsGood) { spin_unlock(&server->srv_lock); return 0; } + server->tcpStatus = CifsInNegotiate; spin_unlock(&server->srv_lock);

@@ -3691,23 +3710,28 @@ cifs_setup_session(const unsigned int xid, struct cifs_ses *ses, bool is_binding = false;

spin_lock(&ses->ses_lock); + cifs_dbg(FYI, "%s: channel connect bitmap: 0x%lx\n", + __func__, ses->chans_need_reconnect); + if (ses->ses_status != SES_GOOD && ses->ses_status != SES_NEW && ses->ses_status != SES_NEED_RECON) { spin_unlock(&ses->ses_lock); - return 0; + return -EHOSTDOWN; }

/* only send once per connect */ spin_lock(&ses->chan_lock); - if (CIFS_ALL_CHANS_GOOD(ses) || - cifs_chan_in_reconnect(ses, server)) { + if (CIFS_ALL_CHANS_GOOD(ses)) { + if (ses->ses_status == SES_NEED_RECON) + ses->ses_status = SES_GOOD; spin_unlock(&ses->chan_lock); spin_unlock(&ses->ses_lock); return 0; } - is_binding = !CIFS_ALL_CHANS_NEED_RECONNECT(ses); + cifs_chan_set_in_reconnect(ses, server); + is_binding = !CIFS_ALL_CHANS_NEED_RECONNECT(ses); spin_unlock(&ses->chan_lock);

if (!is_binding) diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c index caeb92a69b5f..a9fb95b7ef82 100644 --- a/fs/cifs/smb2pdu.c +++ b/fs/cifs/smb2pdu.c @@ -203,6 +203,7 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon, } spin_unlock(&server->srv_lock);

+again: rc = cifs_wait_for_server_reconnect(server, tcon->retry); if (rc) return rc; @@ -221,6 +222,7 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,

nls_codepage = load_nls_default();

+ mutex_lock(&ses->session_mutex); /* * Recheck after acquire mutex. If another thread is negotiating * and the server never sends an answer the socket will be closed @@ -229,6 +231,11 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon, spin_lock(&server->srv_lock); if (server->tcpStatus == CifsNeedReconnect) { spin_unlock(&server->srv_lock); + mutex_unlock(&ses->session_mutex); + + if (tcon->retry) + goto again; + rc = -EHOSTDOWN; goto out; } @@ -238,19 +245,22 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon, * need to prevent multiple threads trying to simultaneously * reconnect the same SMB session */ + spin_lock(&ses->ses_lock); spin_lock(&ses->chan_lock); - if (!cifs_chan_needs_reconnect(ses, server)) { + if (!cifs_chan_needs_reconnect(ses, server) && + ses->ses_status == SES_GOOD) { spin_unlock(&ses->chan_lock); - + spin_unlock(&ses->ses_lock); /* this means that we only need to tree connect */ if (tcon->need_reconnect) goto skip_sess_setup;

+ mutex_unlock(&ses->session_mutex); goto out; } spin_unlock(&ses->chan_lock); + spin_unlock(&ses->ses_lock);

- mutex_lock(&ses->session_mutex); rc = cifs_negotiate_protocol(0, ses, server); if (!rc) { rc = cifs_setup_session(0, ses, server, nls_codepage); @@ -266,10 +276,8 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon, mutex_unlock(&ses->session_mutex); goto out; } - mutex_unlock(&ses->session_mutex);

skip_sess_setup: - mutex_lock(&ses->session_mutex); if (!tcon->need_reconnect) { mutex_unlock(&ses->session_mutex); goto out; @@ -284,7 +292,7 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon, cifs_dbg(FYI, "reconnect tcon rc = %d\n", rc); if (rc) { /* If sess reconnected but tcon didn't, something strange ... */ - pr_warn_once("reconnect tcon failed rc = %d\n", rc); + cifs_dbg(VFS, "reconnect tcon failed rc = %d\n", rc); goto out; }

@@ -1256,9 +1264,9 @@ SMB2_sess_alloc_buffer(struct SMB2_sess_data *sess_data) if (rc) return rc;

- spin_lock(&ses->chan_lock); - is_binding = !CIFS_ALL_CHANS_NEED_RECONNECT(ses); - spin_unlock(&ses->chan_lock); + spin_lock(&ses->ses_lock); + is_binding = (ses->ses_status == SES_GOOD); + spin_unlock(&ses->ses_lock);

if (is_binding) { req->hdr.SessionId = cpu_to_le64(ses->Suid); @@ -1416,9 +1424,9 @@ SMB2_auth_kerberos(struct SMB2_sess_data *sess_data) goto out_put_spnego_key; }

- spin_lock(&ses->chan_lock); - is_binding = !CIFS_ALL_CHANS_NEED_RECONNECT(ses); - spin_unlock(&ses->chan_lock); + spin_lock(&ses->ses_lock); + is_binding = (ses->ses_status == SES_GOOD); + spin_unlock(&ses->ses_lock);

/* keep session key if binding */ if (!is_binding) { @@ -1542,9 +1550,9 @@ SMB2_sess_auth_rawntlmssp_negotiate(struct SMB2_sess_data *sess_data)

cifs_dbg(FYI, "rawntlmssp session setup challenge phase\n");

- spin_lock(&ses->chan_lock); - is_binding = !CIFS_ALL_CHANS_NEED_RECONNECT(ses); - spin_unlock(&ses->chan_lock); + spin_lock(&ses->ses_lock); + is_binding = (ses->ses_status == SES_GOOD); + spin_unlock(&ses->ses_lock);

/* keep existing ses id and flags if binding */ if (!is_binding) { @@ -1610,9 +1618,9 @@ SMB2_sess_auth_rawntlmssp_authenticate(struct SMB2_sess_data *sess_data)

rsp = (struct smb2_sess_setup_rsp *)sess_data->iov[0].iov_base;

- spin_lock(&ses->chan_lock); - is_binding = !CIFS_ALL_CHANS_NEED_RECONNECT(ses); - spin_unlock(&ses->chan_lock); + spin_lock(&ses->ses_lock); + is_binding = (ses->ses_status == SES_GOOD); + spin_unlock(&ses->ses_lock);

/* keep existing ses id and flags if binding */ if (!is_binding) { diff --git a/fs/cifs/smb2transport.c b/fs/cifs/smb2transport.c index d827b7547ffa..790acf65a092 100644 --- a/fs/cifs/smb2transport.c +++ b/fs/cifs/smb2transport.c @@ -81,6 +81,7 @@ int smb2_get_sign_key(__u64 ses_id, struct TCP_Server_Info *server, u8 *key) struct cifs_ses *ses = NULL; int i; int rc = 0; + bool is_binding = false;

spin_lock(&cifs_tcp_ses_lock);

@@ -97,9 +98,12 @@ int smb2_get_sign_key(__u64 ses_id, struct TCP_Server_Info *server, u8 *key) goto out;

found: + spin_lock(&ses->ses_lock); spin_lock(&ses->chan_lock); - if (cifs_chan_needs_reconnect(ses, server) && - !CIFS_ALL_CHANS_NEED_RECONNECT(ses)) { + + is_binding = (cifs_chan_needs_reconnect(ses, server) && + ses->ses_status == SES_GOOD); + if (is_binding) { /* * If we are in the process of binding a new channel * to an existing session, use the master connection @@ -107,6 +111,7 @@ int smb2_get_sign_key(__u64 ses_id, struct TCP_Server_Info *server, u8 *key) */ memcpy(key, ses->smb3signingkey, SMB3_SIGN_KEY_SIZE); spin_unlock(&ses->chan_lock); + spin_unlock(&ses->ses_lock); goto out; }

@@ -119,10 +124,12 @@ int smb2_get_sign_key(__u64 ses_id, struct TCP_Server_Info *server, u8 *key) if (chan->server == server) { memcpy(key, chan->signkey, SMB3_SIGN_KEY_SIZE); spin_unlock(&ses->chan_lock); + spin_unlock(&ses->ses_lock); goto out; } } spin_unlock(&ses->chan_lock); + spin_unlock(&ses->ses_lock);

cifs_dbg(VFS, "%s: Could not find channel signing key for session 0x%llx\n", @@ -392,11 +399,15 @@ generate_smb3signingkey(struct cifs_ses *ses, bool is_binding = false; int chan_index = 0;

+ spin_lock(&ses->ses_lock); spin_lock(&ses->chan_lock); - is_binding = !CIFS_ALL_CHANS_NEED_RECONNECT(ses); + is_binding = (cifs_chan_needs_reconnect(ses, server) && + ses->ses_status == SES_GOOD); + chan_index = cifs_ses_get_chan_index(ses, server); /* TODO: introduce ref counting for channels when the can be freed */ spin_unlock(&ses->chan_lock); + spin_unlock(&ses->ses_lock);

/* * All channels use the same encryption/decryption keys but