From bc962159e8e326af634a506508034a375bf2b858 Mon Sep 17 00:00:00 2001 From: Shyam Prasad N 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 Reviewed-by: Paulo Alcantara (SUSE) Cc: stable@vger.kernel.org Signed-off-by: Steve French --- fs/cifs/connect.c | 48 ++++++++++++++++++++++++++++++++++++------------ fs/cifs/smb2pdu.c | 44 ++++++++++++++++++++++++++------------------ fs/cifs/smb2transport.c | 17 ++++++++++++++--- 3 files changed, 76 insertions(+), 33 deletions(-) diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c index f42cc70..c3162ef 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 caeb92a..a9fb95b 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 @@ skip_sess_setup: 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 d827b75..790acf6 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 @@ found: */ memcpy(key, ses->smb3signingkey, SMB3_SIGN_KEY_SIZE); spin_unlock(&ses->chan_lock); + spin_unlock(&ses->ses_lock); goto out; } @@ -119,10 +124,12 @@ found: 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 -- 2.7.4