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* [WIP] multichannel
@ 2019-09-17 22:14 Aurelien Aptel
  2019-09-17 23:51 ` [WIP v3] multichannel Aurelien Aptel
  0 siblings, 1 reply; 4+ messages in thread
From: Aurelien Aptel @ 2019-09-17 22:14 UTC (permalink / raw)
  To: linux-cifs; +Cc: smfrench, Aurelien Aptel

WIP WIP WIP WIP WIP WIP

New version that applies and work on top of for-next, please test and
comment :)

to test, mount server offering multiple interface with

    -o vers=3.11,multichannel,max_channels=3 to test

WIP WIP WIP WIP WIP WIP

Signed-off-by: Aurelien Aptel <aaptel@suse.com>
---
 fs/cifs/cifs_debug.c    |   6 +-
 fs/cifs/cifs_spnego.c   |   2 +-
 fs/cifs/cifsglob.h      |  28 ++++++-
 fs/cifs/cifsproto.h     |   8 ++
 fs/cifs/connect.c       |  79 ++++++++++++++----
 fs/cifs/sess.c          | 212 +++++++++++++++++++++++++++++++++++++++++++++++-
 fs/cifs/smb2misc.c      |  37 ++++++---
 fs/cifs/smb2ops.c       |  13 ++-
 fs/cifs/smb2pdu.c       | 106 ++++++++++++++----------
 fs/cifs/smb2proto.h     |   3 +-
 fs/cifs/smb2transport.c | 162 +++++++++++++++++++++++++++---------
 fs/cifs/transport.c     |  14 +++-
 12 files changed, 552 insertions(+), 118 deletions(-)

diff --git a/fs/cifs/cifs_debug.c b/fs/cifs/cifs_debug.c
index 0b4eee3bed66..ef454170f37d 100644
--- a/fs/cifs/cifs_debug.c
+++ b/fs/cifs/cifs_debug.c
@@ -410,8 +410,12 @@ static int cifs_debug_data_proc_show(struct seq_file *m, void *v)
 				seq_printf(m, "\n\tServer interfaces: %zu\n",
 					   ses->iface_count);
 			for (j = 0; j < ses->iface_count; j++) {
+				struct cifs_server_iface *iface;
+				iface = &ses->iface_list[j];
 				seq_printf(m, "\t%d)", j);
-				cifs_dump_iface(m, &ses->iface_list[j]);
+				cifs_dump_iface(m, iface);
+				if (is_ses_using_iface(ses, iface))
+					seq_puts(m, "\t\t[CONNECTED]\n");
 			}
 			spin_unlock(&ses->iface_lock);
 		}
diff --git a/fs/cifs/cifs_spnego.c b/fs/cifs/cifs_spnego.c
index 7f01c6e60791..7b9b876b513b 100644
--- a/fs/cifs/cifs_spnego.c
+++ b/fs/cifs/cifs_spnego.c
@@ -98,7 +98,7 @@ struct key_type cifs_spnego_key_type = {
 struct key *
 cifs_get_spnego_key(struct cifs_ses *sesInfo)
 {
-	struct TCP_Server_Info *server = sesInfo->server;
+	struct TCP_Server_Info *server = cifs_ses_server(sesInfo);
 	struct sockaddr_in *sa = (struct sockaddr_in *) &server->dstaddr;
 	struct sockaddr_in6 *sa6 = (struct sockaddr_in6 *) &server->dstaddr;
 	char *description, *dp;
diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 54e204589cb9..b4e1fc815ed7 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -230,7 +230,8 @@ struct smb_version_operations {
 	bool (*compare_fids)(struct cifsFileInfo *, struct cifsFileInfo *);
 	/* setup request: allocate mid, sign message */
 	struct mid_q_entry *(*setup_request)(struct cifs_ses *,
-						struct smb_rqst *);
+					     struct TCP_Server_Info *,
+					     struct smb_rqst *);
 	/* setup async request: allocate mid, sign message */
 	struct mid_q_entry *(*setup_async_request)(struct TCP_Server_Info *,
 						struct smb_rqst *);
@@ -590,6 +591,7 @@ struct smb_vol {
 	bool resilient:1; /* noresilient not required since not fored for CA */
 	bool domainauto:1;
 	bool rdma:1;
+	bool multichannel:1;
 	unsigned int bsize;
 	unsigned int rsize;
 	unsigned int wsize;
@@ -606,6 +608,7 @@ struct smb_vol {
 	__u64 snapshot_time; /* needed for timewarp tokens */
 	__u32 handle_timeout; /* persistent and durable handle timeout in ms */
 	unsigned int max_credits; /* smb3 max_credits 10 < credits < 60000 */
+	unsigned int max_channels;
 	__u16 compression; /* compression algorithm 0xFFFF default 0=disabled */
 	bool rootfs:1; /* if it's a SMB root file system */
 };
@@ -952,11 +955,17 @@ struct cifs_server_iface {
 	struct sockaddr_storage sockaddr;
 };
 
+struct cifs_chan {
+	struct TCP_Server_Info *server;
+	__u8 signkey[SMB3_SIGN_KEY_SIZE];
+};
+
 /*
  * Session structure.  One of these for each uid session with a particular host
  */
 struct cifs_ses {
 	struct list_head smb_ses_list;
+	struct list_head chan_ses_list;
 	struct list_head tcon_list;
 	struct cifs_tcon *tcon_ipc;
 	struct mutex session_mutex;
@@ -982,12 +991,15 @@ struct cifs_ses {
 	bool sign;		/* is signing required? */
 	bool need_reconnect:1; /* connection reset, uid now invalid */
 	bool domainAuto:1;
+	bool binding:1; /* are we binding the session? */
 	__u16 session_flags;
 	__u8 smb3signingkey[SMB3_SIGN_KEY_SIZE];
 	__u8 smb3encryptionkey[SMB3_SIGN_KEY_SIZE];
 	__u8 smb3decryptionkey[SMB3_SIGN_KEY_SIZE];
 	__u8 preauth_sha_hash[SMB2_PREAUTH_HASH_SIZE];
 
+	__u8 binding_preauth_sha_hash[SMB2_PREAUTH_HASH_SIZE];
+
 	/*
 	 * Network interfaces available on the server this session is
 	 * connected to.
@@ -1001,8 +1013,22 @@ struct cifs_ses {
 	struct cifs_server_iface *iface_list;
 	size_t iface_count;
 	unsigned long iface_last_update; /* jiffies */
+
+#define CIFS_MAX_CHANNELS 16
+	struct cifs_chan chans[CIFS_MAX_CHANNELS];
+	size_t chan_count;
+	size_t chan_max;
 };
 
+static inline
+struct TCP_Server_Info *cifs_ses_server(struct cifs_ses *ses)
+{
+	if (ses->binding)
+		return ses->chans[ses->chan_count].server;
+	else
+		return ses->server;
+}
+
 static inline bool
 cap_unix(struct cifs_ses *ses)
 {
diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index 99b1b1ef558c..4cda8bba308b 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -109,6 +109,7 @@ extern int SendReceive(const unsigned int /* xid */ , struct cifs_ses *,
 extern int SendReceiveNoRsp(const unsigned int xid, struct cifs_ses *ses,
 			    char *in_buf, int flags);
 extern struct mid_q_entry *cifs_setup_request(struct cifs_ses *,
+				struct TCP_Server_Info *,
 				struct smb_rqst *);
 extern struct mid_q_entry *cifs_setup_async_request(struct TCP_Server_Info *,
 						struct smb_rqst *);
@@ -241,6 +242,7 @@ extern void cifs_add_pending_open_locked(struct cifs_fid *fid,
 					 struct tcon_link *tlink,
 					 struct cifs_pending_open *open);
 extern void cifs_del_pending_open(struct cifs_pending_open *open);
+extern struct TCP_Server_Info *cifs_get_tcp_session(struct smb_vol *vol);
 extern void cifs_put_tcp_session(struct TCP_Server_Info *server,
 				 int from_reconnect);
 extern void cifs_put_tcon(struct cifs_tcon *tcon);
@@ -582,6 +584,12 @@ void cifs_free_hash(struct crypto_shash **shash, struct sdesc **sdesc);
 
 extern void rqst_page_get_length(struct smb_rqst *rqst, unsigned int page,
 				unsigned int *len, unsigned int *offset);
+int cifs_try_adding_channels(struct cifs_ses *ses);
+int cifs_ses_add_channel(struct cifs_ses *ses,
+				struct cifs_server_iface *iface);
+bool is_server_using_iface(struct TCP_Server_Info *server,
+			   struct cifs_server_iface *iface);
+bool is_ses_using_iface(struct cifs_ses *ses, struct cifs_server_iface *iface);
 
 void extract_unc_hostname(const char *unc, const char **h, size_t *len);
 int copy_path_name(char *dst, const char *src);
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 2850c3ce4391..0d5212cb1ed6 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -97,6 +97,7 @@ enum {
 	Opt_persistent, Opt_nopersistent,
 	Opt_resilient, Opt_noresilient,
 	Opt_domainauto, Opt_rdma, Opt_modesid, Opt_rootfs,
+	Opt_multichannel, Opt_nomultichannel,
 	Opt_compress,
 
 	/* Mount options which take numeric value */
@@ -106,7 +107,7 @@ enum {
 	Opt_min_enc_offload,
 	Opt_blocksize, Opt_rsize, Opt_wsize, Opt_actimeo,
 	Opt_echo_interval, Opt_max_credits, Opt_handletimeout,
-	Opt_snapshot,
+	Opt_snapshot, Opt_max_channels,
 
 	/* Mount options which take string value */
 	Opt_user, Opt_pass, Opt_ip,
@@ -199,6 +200,8 @@ static const match_table_t cifs_mount_option_tokens = {
 	{ Opt_noresilient, "noresilienthandles"},
 	{ Opt_domainauto, "domainauto"},
 	{ Opt_rdma, "rdma"},
+	{ Opt_multichannel, "multichannel" },
+	{ Opt_nomultichannel, "nomultichannel" },
 
 	{ Opt_backupuid, "backupuid=%s" },
 	{ Opt_backupgid, "backupgid=%s" },
@@ -218,6 +221,7 @@ static const match_table_t cifs_mount_option_tokens = {
 	{ Opt_echo_interval, "echo_interval=%s" },
 	{ Opt_max_credits, "max_credits=%s" },
 	{ Opt_snapshot, "snapshot=%s" },
+	{ Opt_max_channels, "max_channels=%s" },
 	{ Opt_compress, "compress=%s" },
 
 	{ Opt_blank_user, "user=" },
@@ -1664,6 +1668,10 @@ cifs_parse_mount_options(const char *mountdata, const char *devname,
 
 	vol->echo_interval = SMB_ECHO_INTERVAL_DEFAULT;
 
+	/* default to no multichannel (single server connection) */
+	vol->multichannel = false;
+	vol->max_channels = 1;
+
 	if (!mountdata)
 		goto cifs_parse_mount_err;
 
@@ -1957,6 +1965,12 @@ cifs_parse_mount_options(const char *mountdata, const char *devname,
 		case Opt_rdma:
 			vol->rdma = true;
 			break;
+		case Opt_multichannel:
+			vol->multichannel = true;
+			break;
+		case Opt_nomultichannel:
+			vol->multichannel = false;
+			break;
 		case Opt_compress:
 			vol->compression = UNKNOWN_TYPE;
 			cifs_dbg(VFS,
@@ -2120,6 +2134,15 @@ cifs_parse_mount_options(const char *mountdata, const char *devname,
 			}
 			vol->max_credits = option;
 			break;
+		case Opt_max_channels:
+			if (get_option_ul(args, &option) || option < 1 ||
+				option > CIFS_MAX_CHANNELS) {
+				cifs_dbg(VFS, "%s: Invalid max_channels value, needs to be 1-%d\n",
+					 __func__, CIFS_MAX_CHANNELS);
+				goto cifs_parse_mount_err;
+			}
+			vol->max_channels = option;
+			break;
 
 		/* String Arguments */
 
@@ -2665,6 +2688,7 @@ cifs_put_tcp_session(struct TCP_Server_Info *server, int from_reconnect)
 {
 	struct task_struct *task;
 
+	cifs_dbg(VFS, "XXX server %px", server);
 	spin_lock(&cifs_tcp_ses_lock);
 	if (--server->srv_count > 0) {
 		spin_unlock(&cifs_tcp_ses_lock);
@@ -2705,7 +2729,7 @@ cifs_put_tcp_session(struct TCP_Server_Info *server, int from_reconnect)
 		send_sig(SIGKILL, task, 1);
 }
 
-static struct TCP_Server_Info *
+struct TCP_Server_Info *
 cifs_get_tcp_session(struct smb_vol *volume_info)
 {
 	struct TCP_Server_Info *tcp_ses = NULL;
@@ -2853,6 +2877,13 @@ static int match_session(struct cifs_ses *ses, struct smb_vol *vol)
 	    vol->sectype != ses->sectype)
 		return 0;
 
+	/*
+	 * If an existing session is limited to less channels than
+	 * requested, it should not be reused
+	 */
+	if (ses->chan_max < vol->max_channels)
+		return 0;
+
 	switch (ses->sectype) {
 	case Kerberos:
 		if (!uid_eq(vol->cred_uid, ses->cred_uid))
@@ -3269,14 +3300,25 @@ cifs_get_smb_ses(struct TCP_Server_Info *server, struct smb_vol *volume_info)
 	ses->sectype = volume_info->sectype;
 	ses->sign = volume_info->sign;
 	mutex_lock(&ses->session_mutex);
+
+	/* add server as first channel */
+	ses->chans[0].server = server;
+	ses->chan_count = 1;
+	ses->chan_max = volume_info->multichannel ? volume_info->max_channels:1;
+
 	rc = cifs_negotiate_protocol(xid, ses);
 	if (!rc)
 		rc = cifs_setup_session(xid, ses, volume_info->local_nls);
+
+	/* each channel uses a different signing key */
+	memcpy(ses->chans[0].signkey, ses->smb3signingkey,
+	       sizeof(ses->smb3signingkey));
+
 	mutex_unlock(&ses->session_mutex);
 	if (rc)
 		goto get_ses_fail;
 
-	/* success, put it on the list */
+	/* success, put it on the list and add it as first channel */
 	spin_lock(&cifs_tcp_ses_lock);
 	list_add(&ses->smb_ses_list, &server->smb_ses_list);
 	spin_unlock(&cifs_tcp_ses_lock);
@@ -4885,6 +4927,7 @@ int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb_vol *vol)
 	cifs_autodisable_serverino(cifs_sb);
 out:
 	free_xid(xid);
+	cifs_try_adding_channels(ses);
 	return mount_setup_tlink(cifs_sb, ses, tcon);
 
 error:
@@ -5130,7 +5173,7 @@ int
 cifs_negotiate_protocol(const unsigned int xid, struct cifs_ses *ses)
 {
 	int rc = 0;
-	struct TCP_Server_Info *server = ses->server;
+	struct TCP_Server_Info *server = cifs_ses_server(ses);
 
 	if (!server->ops->need_neg || !server->ops->negotiate)
 		return -ENOSYS;
@@ -5157,23 +5200,25 @@ cifs_setup_session(const unsigned int xid, struct cifs_ses *ses,
 		   struct nls_table *nls_info)
 {
 	int rc = -ENOSYS;
-	struct TCP_Server_Info *server = ses->server;
-
-	ses->capabilities = server->capabilities;
-	if (linuxExtEnabled == 0)
-		ses->capabilities &= (~server->vals->cap_unix);
+	struct TCP_Server_Info *server = cifs_ses_server(ses);
+
+	if (!ses->binding) {
+		ses->capabilities = server->capabilities;
+		if (linuxExtEnabled == 0)
+			ses->capabilities &= (~server->vals->cap_unix);
+
+		if (ses->auth_key.response) {
+			cifs_dbg(FYI, "Free previous auth_key.response = %p\n",
+				 ses->auth_key.response);
+			kfree(ses->auth_key.response);
+			ses->auth_key.response = NULL;
+			ses->auth_key.len = 0;
+		}
+	}
 
 	cifs_dbg(FYI, "Security Mode: 0x%x Capabilities: 0x%x TimeAdjust: %d\n",
 		 server->sec_mode, server->capabilities, server->timeAdj);
 
-	if (ses->auth_key.response) {
-		cifs_dbg(FYI, "Free previous auth_key.response = %p\n",
-			 ses->auth_key.response);
-		kfree(ses->auth_key.response);
-		ses->auth_key.response = NULL;
-		ses->auth_key.len = 0;
-	}
-
 	if (server->ops->sess_setup)
 		rc = server->ops->sess_setup(xid, ses, nls_info);
 
diff --git a/fs/cifs/sess.c b/fs/cifs/sess.c
index 4c764ff7edd2..473ec41ccb60 100644
--- a/fs/cifs/sess.c
+++ b/fs/cifs/sess.c
@@ -31,6 +31,213 @@
 #include <linux/utsname.h>
 #include <linux/slab.h>
 #include "cifs_spnego.h"
+#include "smb2proto.h"
+
+bool
+is_server_using_iface(struct TCP_Server_Info *server,
+		      struct cifs_server_iface *iface)
+{
+	struct sockaddr_in *i4 = (struct sockaddr_in *)&iface->sockaddr;
+	struct sockaddr_in6 *i6 = (struct sockaddr_in6 *)&iface->sockaddr;
+	struct sockaddr_in *s4 = (struct sockaddr_in *)&server->dstaddr;
+	struct sockaddr_in6 *s6 = (struct sockaddr_in6 *)&server->dstaddr;
+
+	if (server->dstaddr.ss_family != iface->sockaddr.ss_family)
+		return false;
+	if (server->dstaddr.ss_family == AF_INET) {
+		if (s4->sin_addr.s_addr != i4->sin_addr.s_addr)
+			return false;
+	} else if (server->dstaddr.ss_family == AF_INET6) {
+		if (memcmp(&s6->sin6_addr, &i6->sin6_addr,
+			   sizeof(i6->sin6_addr)) != 0)
+			return false;
+	} else {
+		/* unknown family.. */
+		return false;
+	}
+	return true;
+}
+
+bool is_ses_using_iface(struct cifs_ses *ses, struct cifs_server_iface *iface)
+{
+	int i;
+	for (i = 0; i < ses->chan_count; i++) {
+		if (is_server_using_iface(ses->chans[i].server, iface))
+			return true;
+	}
+	return false;
+}
+
+/* returns number of channels added */
+int cifs_try_adding_channels(struct cifs_ses *ses)
+{
+	int old_chan_count = ses->chan_count;
+	int left = ses->chan_max - ses->chan_count;
+	int i = 0;
+	int rc = 0;
+
+	if (left <= 0) {
+		cifs_dbg(FYI,
+			 "ses already at max_channels (%zu), nothing to open\n",
+			 ses->chan_max);
+		return 0;
+	}
+
+	if (ses->server->dialect != SMB311_PROT_ID) {
+		cifs_dbg(VFS, "multichannel is not supported on this protocol version, use 3.1.1\n");
+		return 0;
+	}
+
+	/* ifaces are sorted by speed, try them in order */
+	for (i = 0; left > 0 && i < ses->iface_count; i++) {
+		struct cifs_server_iface *iface;
+
+		iface = &ses->iface_list[i];
+		if (is_ses_using_iface(ses, iface) && !iface->rss_capable)
+			continue;
+
+		rc = cifs_ses_add_channel(ses, iface);
+		if (rc) {
+			cifs_dbg(FYI, "failed to open extra channel\n");
+			continue;
+		}
+
+		cifs_dbg(FYI, "sucessfully opened new channel\n");
+		left--;
+	}
+
+	/*
+	 * TODO: if we still have channels left to open try to connect
+	 * to same RSS-capable iface multiple times
+	 */
+
+	return ses->chan_count - old_chan_count;
+}
+
+int
+cifs_ses_add_channel(struct cifs_ses *ses, struct cifs_server_iface *iface)
+{
+	struct cifs_chan *chan;
+	struct smb_vol vol = {0};
+	const char unc_fmt[] = "\\%s\\foo";
+	char unc[sizeof(unc_fmt)+SERVER_NAME_LEN_WITH_NULL] = {0};
+	struct sockaddr_in *ipv4 = (struct sockaddr_in *)&iface->sockaddr;
+	struct sockaddr_in6 *ipv6 = (struct sockaddr_in6 *)&iface->sockaddr;
+	int rc;
+	unsigned int xid = get_xid();
+
+	cifs_dbg(FYI, "adding channel to ses %p (speed:%zu bps rdma:%s ",
+		 ses, iface->speed, iface->rdma_capable ? "yes" : "no");
+	if (iface->sockaddr.ss_family == AF_INET)
+		cifs_dbg(FYI, "ip:%pI4)\n", &ipv4->sin_addr);
+	else
+		cifs_dbg(FYI, "ip:%pI6)\n", &ipv6->sin6_addr);
+
+	/*
+	 * Setup a smb_vol with mostly the same info as the existing
+	 * session and overwrite it with the requested iface data.
+	 *
+	 * We need to setup at least the fields used for negprot and
+	 * sesssetup.
+	 *
+	 * We only need the volume here, so we can reuse memory from
+	 * the session and server without caring about memory
+	 * management.
+	 */
+
+	/* Always make new connection for now (TODO?) */
+	vol.nosharesock = true;
+
+	/* Auth */
+	vol.domainauto = ses->domainAuto;
+	vol.domainname = ses->domainName;
+	vol.username = ses->user_name;
+	vol.password = ses->password;
+	vol.sectype = ses->sectype;
+	vol.sign = ses->sign;
+
+	/* UNC and paths */
+	/* XXX: Use ses->server->hostname? */
+	sprintf(unc, unc_fmt, ses->serverName);
+	vol.UNC = unc;
+	vol.prepath = "";
+
+	/* Require SMB3.1.1 */
+	vol.vals = &smb311_values;
+	vol.ops = &smb311_operations;
+
+	vol.noblocksnd = ses->server->noblocksnd;
+	vol.noautotune = ses->server->noautotune;
+	vol.sockopt_tcp_nodelay = ses->server->tcp_nodelay;
+	vol.echo_interval = ses->server->echo_interval / HZ;
+
+	/*
+	 * This will be used for encoding/decoding user/domain/pw
+	 * during sess setup auth.
+	 *
+	 * XXX: We use the default for simplicity but the proper way
+	 * would be to use the one that ses used, which is not
+	 * stored. This might break when dealing with non-ascii
+	 * strings.
+	 */
+	vol.local_nls = load_nls_default();
+
+	/* Use RDMA if possible */
+	vol.rdma = iface->rdma_capable;
+	memcpy(&vol.dstaddr, &iface->sockaddr, sizeof(struct sockaddr_storage));
+
+	mutex_lock(&ses->session_mutex);
+
+	chan = &ses->chans[ses->chan_count];
+	chan->server = cifs_get_tcp_session(&vol);
+	if (IS_ERR(chan->server)) {
+		rc = PTR_ERR(chan->server);
+		chan->server = NULL;
+		goto out;
+	}
+
+	/*
+	 * We need to allocate the server crypto now as we will need
+	 * to sign packets before we generate the channel signing key
+	 * (we sign with the session key)
+	 */
+	rc = smb311_crypto_shash_allocate(chan->server);
+	if (rc) {
+		cifs_dbg(VFS, "%s: crypto alloc failed\n", __func__);
+		goto out;
+	}
+
+	ses->binding = true;
+	rc = cifs_negotiate_protocol(xid, ses);
+	if (rc)
+		goto out;
+
+	rc = cifs_setup_session(xid, ses, vol.local_nls);
+	if (rc)
+		goto out;
+
+	/* success, put it on the list
+	 * XXX: sharing ses between 2 tcp server is not possible, the
+	 * way "internal" linked lists works in linux makes element
+	 * only able to belong to one list
+	 *
+	 * the binding session is already established so the rest of
+	 * the code should be able to look it up, no need to add the
+	 * ses to the new server.
+	 */
+
+	ses->chan_count++;
+
+out:
+	ses->binding = false;
+	mutex_unlock(&ses->session_mutex);
+
+	if (rc && chan->server)
+		cifs_put_tcp_session(chan->server, 0);
+	unload_nls(vol.local_nls);
+
+	return rc;
+}
 
 static __u32 cifs_ssetup_hdr(struct cifs_ses *ses, SESSION_SETUP_ANDX *pSMB)
 {
@@ -342,6 +549,7 @@ int decode_ntlmssp_challenge(char *bcc_ptr, int blob_len,
 void build_ntlmssp_negotiate_blob(unsigned char *pbuffer,
 					 struct cifs_ses *ses)
 {
+	struct TCP_Server_Info *server = cifs_ses_server(ses);
 	NEGOTIATE_MESSAGE *sec_blob = (NEGOTIATE_MESSAGE *)pbuffer;
 	__u32 flags;
 
@@ -354,9 +562,9 @@ void build_ntlmssp_negotiate_blob(unsigned char *pbuffer,
 		NTLMSSP_NEGOTIATE_128 | NTLMSSP_NEGOTIATE_UNICODE |
 		NTLMSSP_NEGOTIATE_NTLM | NTLMSSP_NEGOTIATE_EXTENDED_SEC |
 		NTLMSSP_NEGOTIATE_SEAL;
-	if (ses->server->sign)
+	if (server->sign)
 		flags |= NTLMSSP_NEGOTIATE_SIGN;
-	if (!ses->server->session_estab || ses->ntlmssp->sesskey_per_smbsess)
+	if (!server->session_estab || ses->ntlmssp->sesskey_per_smbsess)
 		flags |= NTLMSSP_NEGOTIATE_KEY_XCH;
 
 	sec_blob->NegotiateFlags = cpu_to_le32(flags);
diff --git a/fs/cifs/smb2misc.c b/fs/cifs/smb2misc.c
index e311f58dc1c8..a95ed951c67f 100644
--- a/fs/cifs/smb2misc.c
+++ b/fs/cifs/smb2misc.c
@@ -29,6 +29,7 @@
 #include "cifs_unicode.h"
 #include "smb2status.h"
 #include "smb2glob.h"
+#include "nterr.h"
 
 static int
 check_smb2_hdr(struct smb2_sync_hdr *shdr, __u64 mid)
@@ -788,23 +789,37 @@ smb311_update_preauth_hash(struct cifs_ses *ses, struct kvec *iov, int nvec)
 	int i, rc;
 	struct sdesc *d;
 	struct smb2_sync_hdr *hdr;
+	struct TCP_Server_Info *server = cifs_ses_server(ses);
 
-	if (ses->server->tcpStatus == CifsGood) {
-		/* skip non smb311 connections */
-		if (ses->server->dialect != SMB311_PROT_ID)
-			return 0;
+	hdr = (struct smb2_sync_hdr *)iov[0].iov_base;
+	/* neg prot are always taken */
+	if (hdr->Command == SMB2_NEGOTIATE)
+		goto ok;
 
-		/* skip last sess setup response */
-		hdr = (struct smb2_sync_hdr *)iov[0].iov_base;
-		if (hdr->Flags & SMB2_FLAGS_SIGNED)
-			return 0;
-	}
+	/*
+	 * If we process a command which wasn't a negprot it means the
+	 * neg prot was already done, so the server dialect was set
+	 * and we can test it. Preauth requires 3.1.1 for now.
+	 */
+	if (server->dialect != SMB311_PROT_ID)
+		return 0;
+
+	if (hdr->Command != SMB2_SESSION_SETUP)
+		return 0;
+
+	/* skip last sess setup response */
+	if ((hdr->Flags & SMB2_FLAGS_SERVER_TO_REDIR)
+	    && (hdr->Status == NT_STATUS_OK
+		|| (hdr->Status !=
+		    cpu_to_le32(NT_STATUS_MORE_PROCESSING_REQUIRED))))
+		return 0;
 
-	rc = smb311_crypto_shash_allocate(ses->server);
+ok:
+	rc = smb311_crypto_shash_allocate(server);
 	if (rc)
 		return rc;
 
-	d = ses->server->secmech.sdescsha512;
+	d = server->secmech.sdescsha512;
 	rc = crypto_shash_init(&d->shash);
 	if (rc) {
 		cifs_dbg(VFS, "%s: could not init sha512 shash\n", __func__);
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index eaed18061314..0e66dc1aa1c9 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -10,6 +10,7 @@
 #include <linux/falloc.h>
 #include <linux/scatterlist.h>
 #include <linux/uuid.h>
+#include <linux/sort.h>
 #include <crypto/aead.h>
 #include "cifsglob.h"
 #include "smb2pdu.h"
@@ -315,7 +316,7 @@ smb2_negotiate(const unsigned int xid, struct cifs_ses *ses)
 {
 	int rc;
 
-	ses->server->CurrentMid = 0;
+	cifs_ses_server(ses)->CurrentMid = 0;
 	rc = SMB2_negotiate(xid, ses);
 	/* BB we probably don't need to retry with modern servers */
 	if (rc == -EAGAIN)
@@ -558,6 +559,13 @@ parse_server_interfaces(struct network_interface_info_ioctl_rsp *buf,
 	return rc;
 }
 
+static int compare_iface(const void *ia, const void *ib)
+{
+	const struct cifs_server_iface *a = (struct cifs_server_iface *)ia;
+	const struct cifs_server_iface *b = (struct cifs_server_iface *)ib;
+
+	return a->speed == b->speed ? 0 : (a->speed > b->speed ? -1 : 1);
+}
 
 static int
 SMB3_request_interfaces(const unsigned int xid, struct cifs_tcon *tcon)
@@ -587,6 +595,9 @@ SMB3_request_interfaces(const unsigned int xid, struct cifs_tcon *tcon)
 	if (rc)
 		goto out;
 
+	/* sort interfaces from fastest to slowest */
+	sort(iface_list, iface_count, sizeof(*iface_list), compare_iface, NULL);
+
 	spin_lock(&ses->iface_lock);
 	kfree(ses->iface_list);
 	ses->iface_list = iface_list;
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 87066f1af12c..8bcb278fdb0a 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -789,7 +789,7 @@ SMB2_negotiate(const unsigned int xid, struct cifs_ses *ses)
 	struct kvec rsp_iov;
 	int rc = 0;
 	int resp_buftype;
-	struct TCP_Server_Info *server = ses->server;
+	struct TCP_Server_Info *server = cifs_ses_server(ses);
 	int blob_offset, blob_length;
 	char *security_blob;
 	int flags = CIFS_NEG_OP;
@@ -811,7 +811,7 @@ SMB2_negotiate(const unsigned int xid, struct cifs_ses *ses)
 	memset(server->preauth_sha_hash, 0, SMB2_PREAUTH_HASH_SIZE);
 	memset(ses->preauth_sha_hash, 0, SMB2_PREAUTH_HASH_SIZE);
 
-	if (strcmp(ses->server->vals->version_string,
+	if (strcmp(server->vals->version_string,
 		   SMB3ANY_VERSION_STRING) == 0) {
 		req->Dialects[0] = cpu_to_le16(SMB30_PROT_ID);
 		req->Dialects[1] = cpu_to_le16(SMB302_PROT_ID);
@@ -827,7 +827,7 @@ SMB2_negotiate(const unsigned int xid, struct cifs_ses *ses)
 		total_len += 8;
 	} else {
 		/* otherwise send specific dialect */
-		req->Dialects[0] = cpu_to_le16(ses->server->vals->protocol_id);
+		req->Dialects[0] = cpu_to_le16(server->vals->protocol_id);
 		req->DialectCount = cpu_to_le16(1);
 		total_len += 2;
 	}
@@ -1169,7 +1169,7 @@ SMB2_sess_alloc_buffer(struct SMB2_sess_data *sess_data)
 	int rc;
 	struct cifs_ses *ses = sess_data->ses;
 	struct smb2_sess_setup_req *req;
-	struct TCP_Server_Info *server = ses->server;
+	struct TCP_Server_Info *server = cifs_ses_server(ses);
 	unsigned int total_len;
 
 	rc = smb2_plain_req_init(SMB2_SESSION_SETUP, NULL, (void **) &req,
@@ -1177,13 +1177,18 @@ SMB2_sess_alloc_buffer(struct SMB2_sess_data *sess_data)
 	if (rc)
 		return rc;
 
-	/* First session, not a reauthenticate */
-	req->sync_hdr.SessionId = 0;
-
-	/* if reconnect, we need to send previous sess id, otherwise it is 0 */
-	req->PreviousSessionId = sess_data->previous_session;
-
-	req->Flags = 0; /* MBZ */
+	if (sess_data->ses->binding) {
+		req->sync_hdr.SessionId = sess_data->ses->Suid;
+		req->sync_hdr.Flags |= SMB2_FLAGS_SIGNED;
+		req->PreviousSessionId = 0;
+		req->Flags = SMB2_SESSION_REQ_FLAG_BINDING;
+	} else {
+		/* First session, not a reauthenticate */
+		req->sync_hdr.SessionId = 0;
+		/* if reconnect, we need to send previous sess id, otherwise it is 0 */
+		req->PreviousSessionId = sess_data->previous_session;
+		req->Flags = 0; /* MBZ */
+	}
 
 	/* enough to enable echos and oplocks and one max size write */
 	req->sync_hdr.CreditRequest = cpu_to_le16(130);
@@ -1256,28 +1261,33 @@ SMB2_sess_establish_session(struct SMB2_sess_data *sess_data)
 {
 	int rc = 0;
 	struct cifs_ses *ses = sess_data->ses;
+	struct TCP_Server_Info *server = cifs_ses_server(ses);
 
-	mutex_lock(&ses->server->srv_mutex);
-	if (ses->server->ops->generate_signingkey) {
-		rc = ses->server->ops->generate_signingkey(ses);
+	mutex_lock(&server->srv_mutex);
+	if (server->ops->generate_signingkey) {
+		rc = server->ops->generate_signingkey(ses);
 		if (rc) {
 			cifs_dbg(FYI,
 				"SMB3 session key generation failed\n");
-			mutex_unlock(&ses->server->srv_mutex);
+			mutex_unlock(&server->srv_mutex);
 			return rc;
 		}
 	}
-	if (!ses->server->session_estab) {
-		ses->server->sequence_number = 0x2;
-		ses->server->session_estab = true;
+	if (!server->session_estab) {
+		server->sequence_number = 0x2;
+		server->session_estab = true;
 	}
-	mutex_unlock(&ses->server->srv_mutex);
+	mutex_unlock(&server->srv_mutex);
 
 	cifs_dbg(FYI, "SMB2/3 session established successfully\n");
-	spin_lock(&GlobalMid_Lock);
-	ses->status = CifsGood;
-	ses->need_reconnect = false;
-	spin_unlock(&GlobalMid_Lock);
+	/* keep exising ses state if binding */
+	if (!ses->binding) {
+		spin_lock(&GlobalMid_Lock);
+		ses->status = CifsGood;
+		ses->need_reconnect = false;
+		spin_unlock(&GlobalMid_Lock);
+	}
+
 	return rc;
 }
 
@@ -1315,16 +1325,19 @@ SMB2_auth_kerberos(struct SMB2_sess_data *sess_data)
 		goto out_put_spnego_key;
 	}
 
-	ses->auth_key.response = kmemdup(msg->data, msg->sesskey_len,
-					 GFP_KERNEL);
-	if (!ses->auth_key.response) {
-		cifs_dbg(VFS,
-			"Kerberos can't allocate (%u bytes) memory",
-			msg->sesskey_len);
-		rc = -ENOMEM;
-		goto out_put_spnego_key;
+	/* keep session key if binding */
+	if (!ses->binding) {
+		ses->auth_key.response = kmemdup(msg->data, msg->sesskey_len,
+						 GFP_KERNEL);
+		if (!ses->auth_key.response) {
+			cifs_dbg(VFS,
+				 "Kerberos can't allocate (%u bytes) memory",
+				 msg->sesskey_len);
+			rc = -ENOMEM;
+			goto out_put_spnego_key;
+		}
+		ses->auth_key.len = msg->sesskey_len;
 	}
-	ses->auth_key.len = msg->sesskey_len;
 
 	sess_data->iov[1].iov_base = msg->data + msg->sesskey_len;
 	sess_data->iov[1].iov_len = msg->secblob_len;
@@ -1334,9 +1347,11 @@ SMB2_auth_kerberos(struct SMB2_sess_data *sess_data)
 		goto out_put_spnego_key;
 
 	rsp = (struct smb2_sess_setup_rsp *)sess_data->iov[0].iov_base;
-	ses->Suid = rsp->sync_hdr.SessionId;
-
-	ses->session_flags = le16_to_cpu(rsp->SessionFlags);
+	/* keep session id and flags if binding */
+	if (!ses->binding) {
+		ses->Suid = rsp->sync_hdr.SessionId;
+		ses->session_flags = le16_to_cpu(rsp->SessionFlags);
+	}
 
 	rc = SMB2_sess_establish_session(sess_data);
 out_put_spnego_key:
@@ -1430,9 +1445,11 @@ SMB2_sess_auth_rawntlmssp_negotiate(struct SMB2_sess_data *sess_data)
 
 	cifs_dbg(FYI, "rawntlmssp session setup challenge phase\n");
 
-
-	ses->Suid = rsp->sync_hdr.SessionId;
-	ses->session_flags = le16_to_cpu(rsp->SessionFlags);
+	/* keep existing ses id and flags if binding */
+	if (!ses->binding) {
+		ses->Suid = rsp->sync_hdr.SessionId;
+		ses->session_flags = le16_to_cpu(rsp->SessionFlags);
+	}
 
 out:
 	kfree(ntlmssp_blob);
@@ -1489,8 +1506,11 @@ SMB2_sess_auth_rawntlmssp_authenticate(struct SMB2_sess_data *sess_data)
 
 	rsp = (struct smb2_sess_setup_rsp *)sess_data->iov[0].iov_base;
 
-	ses->Suid = rsp->sync_hdr.SessionId;
-	ses->session_flags = le16_to_cpu(rsp->SessionFlags);
+	/* keep existing ses id and flags if binding */
+	if (!ses->binding) {
+		ses->Suid = rsp->sync_hdr.SessionId;
+		ses->session_flags = le16_to_cpu(rsp->SessionFlags);
+	}
 
 	rc = SMB2_sess_establish_session(sess_data);
 out:
@@ -1507,7 +1527,7 @@ SMB2_select_sec(struct cifs_ses *ses, struct SMB2_sess_data *sess_data)
 {
 	int type;
 
-	type = smb2_select_sectype(ses->server, ses->sectype);
+	type = smb2_select_sectype(cifs_ses_server(ses), ses->sectype);
 	cifs_dbg(FYI, "sess setup type %d\n", type);
 	if (type == Unspecified) {
 		cifs_dbg(VFS,
@@ -1535,7 +1555,7 @@ SMB2_sess_setup(const unsigned int xid, struct cifs_ses *ses,
 		const struct nls_table *nls_cp)
 {
 	int rc = 0;
-	struct TCP_Server_Info *server = ses->server;
+	struct TCP_Server_Info *server = cifs_ses_server(ses);
 	struct SMB2_sess_data *sess_data;
 
 	cifs_dbg(FYI, "Session Setup\n");
@@ -1561,7 +1581,7 @@ SMB2_sess_setup(const unsigned int xid, struct cifs_ses *ses,
 	/*
 	 * Initialize the session hash with the server one.
 	 */
-	memcpy(ses->preauth_sha_hash, ses->server->preauth_sha_hash,
+	memcpy(ses->preauth_sha_hash, server->preauth_sha_hash,
 	       SMB2_PREAUTH_HASH_SIZE);
 
 	while (sess_data->func)
diff --git a/fs/cifs/smb2proto.h b/fs/cifs/smb2proto.h
index 67a91b11fd59..804b6dc5546b 100644
--- a/fs/cifs/smb2proto.h
+++ b/fs/cifs/smb2proto.h
@@ -46,7 +46,8 @@ extern int smb2_verify_signature(struct smb_rqst *, struct TCP_Server_Info *);
 extern int smb2_check_receive(struct mid_q_entry *mid,
 			      struct TCP_Server_Info *server, bool log_error);
 extern struct mid_q_entry *smb2_setup_request(struct cifs_ses *ses,
-			      struct smb_rqst *rqst);
+					      struct TCP_Server_Info *,
+					      struct smb_rqst *rqst);
 extern struct mid_q_entry *smb2_setup_async_request(
 			struct TCP_Server_Info *server, struct smb_rqst *rqst);
 extern struct cifs_ses *smb2_find_smb_ses(struct TCP_Server_Info *server,
diff --git a/fs/cifs/smb2transport.c b/fs/cifs/smb2transport.c
index 148d7942c796..539cf2fc1f3b 100644
--- a/fs/cifs/smb2transport.c
+++ b/fs/cifs/smb2transport.c
@@ -48,7 +48,7 @@ smb2_crypto_shash_allocate(struct TCP_Server_Info *server)
 			       &server->secmech.sdeschmacsha256);
 }
 
-static int
+int
 smb3_crypto_shash_allocate(struct TCP_Server_Info *server)
 {
 	struct cifs_secmech *p = &server->secmech;
@@ -98,6 +98,47 @@ smb311_crypto_shash_allocate(struct TCP_Server_Info *server)
 	return rc;
 }
 
+u8 *smb2_find_chan_signkey(struct cifs_ses *ses, struct TCP_Server_Info *server)
+{
+	int i;
+	struct cifs_chan *chan;
+	int count;
+	spin_lock(&cifs_tcp_ses_lock);
+	count = ses->chan_count;
+	if (ses->binding)
+		count++;
+	for (i = 0; i < count; i++) {
+		chan = ses->chans + i;
+		if (chan->server == server) {
+			spin_unlock(&cifs_tcp_ses_lock);
+			return chan->signkey;
+		}
+	}
+	spin_unlock(&cifs_tcp_ses_lock);
+	return NULL;
+}
+
+struct cifs_ses *
+smb2_find_global_smb_ses(__u64 ses_id)
+{
+	struct TCP_Server_Info *server;
+	struct cifs_ses *ses;
+	cifs_dbg(VFS, "XXX: searching for sesid %llu", ses_id);
+	spin_lock(&cifs_tcp_ses_lock);
+	list_for_each_entry(server, &cifs_tcp_ses_list, tcp_ses_list) {
+		cifs_dbg(VFS, "XXX: server %px ", server);
+		list_for_each_entry(ses, &server->smb_ses_list, smb_ses_list) {
+			cifs_dbg(VFS, "XXX: ses %px ", ses);
+			if (ses->Suid == ses_id) {
+				spin_unlock(&cifs_tcp_ses_lock);
+				return ses;
+			}
+		}
+	}
+	spin_unlock(&cifs_tcp_ses_lock);
+	return NULL;
+}
+
 static struct cifs_ses *
 smb2_find_smb_ses_unlocked(struct TCP_Server_Info *server, __u64 ses_id)
 {
@@ -328,21 +369,34 @@ generate_smb3signingkey(struct cifs_ses *ses,
 {
 	int rc;
 
-	rc = generate_key(ses, ptriplet->signing.label,
-			  ptriplet->signing.context, ses->smb3signingkey,
-			  SMB3_SIGN_KEY_SIZE);
-	if (rc)
-		return rc;
-
-	rc = generate_key(ses, ptriplet->encryption.label,
-			  ptriplet->encryption.context, ses->smb3encryptionkey,
-			  SMB3_SIGN_KEY_SIZE);
-	if (rc)
-		return rc;
-
-	rc = generate_key(ses, ptriplet->decryption.label,
-			  ptriplet->decryption.context,
-			  ses->smb3decryptionkey, SMB3_SIGN_KEY_SIZE);
+	if (ses->binding) {
+		struct TCP_Server_Info *server;
+		cifs_dbg(VFS, "XXX: BINDING! gen signkey");
+		server = cifs_ses_server(ses);
+		rc = generate_key(ses, ptriplet->signing.label,
+				  ptriplet->signing.context,
+				  smb2_find_chan_signkey(ses, server),
+				  SMB3_SIGN_KEY_SIZE);
+		if (rc)
+			return rc;
+	} else {
+		rc = generate_key(ses, ptriplet->signing.label,
+				  ptriplet->signing.context,
+				  ses->smb3signingkey,
+				  SMB3_SIGN_KEY_SIZE);
+		if (rc)
+			return rc;
+		rc = generate_key(ses, ptriplet->encryption.label,
+				  ptriplet->encryption.context,
+				  ses->smb3encryptionkey,
+				  SMB3_SIGN_KEY_SIZE);
+		rc = generate_key(ses, ptriplet->decryption.label,
+				  ptriplet->decryption.context,
+				  ses->smb3decryptionkey,
+				  SMB3_SIGN_KEY_SIZE);
+		if (rc)
+			return rc;
+	}
 
 	if (rc)
 		return rc;
@@ -434,18 +488,35 @@ smb3_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
 	struct cifs_ses *ses;
 	struct shash_desc *shash = &server->secmech.sdesccmacaes->shash;
 	struct smb_rqst drqst;
+	u8 *key;
 
-	ses = smb2_find_smb_ses(server, shdr->SessionId);
+	ses = smb2_find_global_smb_ses(shdr->SessionId);
 	if (!ses) {
 		cifs_server_dbg(VFS, "%s: Could not find session\n", __func__);
 		return 0;
 	}
 
+	/*
+	 * If we are binding an existing session use the session key,
+	 * otherwise use the channel key
+	 */
+	if (ses->binding) {
+		key = ses->smb3signingkey;
+		cifs_dbg(VFS, "XXX: using bind ses key %px", key);
+	} else {
+		key = smb2_find_chan_signkey(ses, server);
+		cifs_dbg(VFS, "XXX: using chan ses key %px", key);
+		if (!key) {
+			cifs_dbg(VFS, "XXX: could not find channel key");
+			return 0;
+		}
+        }
+
 	memset(smb3_signature, 0x0, SMB2_CMACAES_SIZE);
 	memset(shdr->Signature, 0x0, SMB2_SIGNATURE_SIZE);
 
 	rc = crypto_shash_setkey(server->secmech.cmacaes,
-				 ses->smb3signingkey, SMB2_CMACAES_SIZE);
+				 key, SMB2_CMACAES_SIZE);
 	if (rc) {
 		cifs_server_dbg(VFS, "%s: Could not set key for cmac aes\n", __func__);
 		return rc;
@@ -494,18 +565,35 @@ static int
 smb2_sign_rqst(struct smb_rqst *rqst, struct TCP_Server_Info *server)
 {
 	int rc = 0;
-	struct smb2_sync_hdr *shdr =
-			(struct smb2_sync_hdr *)rqst->rq_iov[0].iov_base;
+	struct smb2_sync_hdr *shdr;
+	struct smb2_sess_setup_req *ssr;
+	bool is_binding;
+	bool is_signed;
 
-	if (!(shdr->Flags & SMB2_FLAGS_SIGNED) ||
-	    server->tcpStatus == CifsNeedNegotiate)
-		return rc;
+	shdr = (struct smb2_sync_hdr *)rqst->rq_iov[0].iov_base;
+	ssr = (struct smb2_sess_setup_req *)shdr;
 
-	if (!server->session_estab) {
+	is_binding = shdr->Command == SMB2_SESSION_SETUP &&
+		(ssr->Flags & SMB2_SESSION_REQ_FLAG_BINDING);
+	is_signed = shdr->Flags & SMB2_FLAGS_SIGNED;
+
+	printk(KERN_WARNING "XXX: sign_rqst\n");
+
+	if (!is_signed) {
+		printk(KERN_WARNING "XXX: no signed flag\n");
+		return 0;
+	}
+	if (server->tcpStatus == CifsNeedNegotiate) {
+		printk(KERN_WARNING "XXX: need nego\n");
+		return 0;
+	}
+	if (!is_binding && !server->session_estab) {
 		strncpy(shdr->Signature, "BSRSPYL", 8);
-		return rc;
+		printk(KERN_WARNING "XXX: !session_estab\n");
+		return 0;
 	}
 
+	printk(KERN_WARNING "XXX: actually signing!\n");
 	rc = server->ops->calc_signature(rqst, server);
 
 	return rc;
@@ -610,18 +698,18 @@ smb2_mid_entry_alloc(const struct smb2_sync_hdr *shdr,
 }
 
 static int
-smb2_get_mid_entry(struct cifs_ses *ses, struct smb2_sync_hdr *shdr,
+smb2_get_mid_entry(struct cifs_ses *ses, struct TCP_Server_Info *server, struct smb2_sync_hdr *shdr,
 		   struct mid_q_entry **mid)
 {
-	if (ses->server->tcpStatus == CifsExiting)
+	if (server->tcpStatus == CifsExiting)
 		return -ENOENT;
 
-	if (ses->server->tcpStatus == CifsNeedReconnect) {
+	if (server->tcpStatus == CifsNeedReconnect) {
 		cifs_dbg(FYI, "tcp session dead - return to caller to retry\n");
 		return -EAGAIN;
 	}
 
-	if (ses->server->tcpStatus == CifsNeedNegotiate &&
+	if (server->tcpStatus == CifsNeedNegotiate &&
 	   shdr->Command != SMB2_NEGOTIATE)
 		return -EAGAIN;
 
@@ -638,11 +726,11 @@ smb2_get_mid_entry(struct cifs_ses *ses, struct smb2_sync_hdr *shdr,
 		/* else ok - we are shutting down the session */
 	}
 
-	*mid = smb2_mid_entry_alloc(shdr, ses->server);
+	*mid = smb2_mid_entry_alloc(shdr, server);
 	if (*mid == NULL)
 		return -ENOMEM;
 	spin_lock(&GlobalMid_Lock);
-	list_add_tail(&(*mid)->qhead, &ses->server->pending_mid_q);
+	list_add_tail(&(*mid)->qhead, &server->pending_mid_q);
 	spin_unlock(&GlobalMid_Lock);
 
 	return 0;
@@ -675,24 +763,24 @@ smb2_check_receive(struct mid_q_entry *mid, struct TCP_Server_Info *server,
 }
 
 struct mid_q_entry *
-smb2_setup_request(struct cifs_ses *ses, struct smb_rqst *rqst)
+smb2_setup_request(struct cifs_ses *ses, struct TCP_Server_Info *server, struct smb_rqst *rqst)
 {
 	int rc;
 	struct smb2_sync_hdr *shdr =
 			(struct smb2_sync_hdr *)rqst->rq_iov[0].iov_base;
 	struct mid_q_entry *mid;
 
-	smb2_seq_num_into_buf(ses->server, shdr);
+	smb2_seq_num_into_buf(server, shdr);
 
-	rc = smb2_get_mid_entry(ses, shdr, &mid);
+	rc = smb2_get_mid_entry(ses, server, shdr, &mid);
 	if (rc) {
-		revert_current_mid_from_hdr(ses->server, shdr);
+		revert_current_mid_from_hdr(server, shdr);
 		return ERR_PTR(rc);
 	}
 
-	rc = smb2_sign_rqst(rqst, ses->server);
+	rc = smb2_sign_rqst(rqst, server);
 	if (rc) {
-		revert_current_mid_from_hdr(ses->server, shdr);
+		revert_current_mid_from_hdr(server, shdr);
 		cifs_delete_mid(mid);
 		return ERR_PTR(rc);
 	}
diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
index 308ad0f495e1..a4c2d62ee437 100644
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -923,7 +923,7 @@ cifs_check_receive(struct mid_q_entry *mid, struct TCP_Server_Info *server,
 }
 
 struct mid_q_entry *
-cifs_setup_request(struct cifs_ses *ses, struct smb_rqst *rqst)
+cifs_setup_request(struct cifs_ses *ses, struct TCP_Server_Info *ignored, struct smb_rqst *rqst)
 {
 	int rc;
 	struct smb_hdr *hdr = (struct smb_hdr *)rqst->rq_iov[0].iov_base;
@@ -995,7 +995,15 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
 		return -EIO;
 	}
 
-	server = ses->server;
+	if (!ses->binding) {
+		uint index = ((unsigned)get_random_int()) % ses->chan_count;
+		cifs_dbg(VFS, "XXX: send/recv: using random channel %d", index);
+		server = ses->chans[index].server;
+	} else {
+		cifs_dbg(VFS, "XXX: send/recv: binding, using last serv");
+		server = cifs_ses_server(ses);
+	}
+
 	if (server->tcpStatus == CifsExiting)
 		return -ENOENT;
 
@@ -1040,7 +1048,7 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
 	}
 
 	for (i = 0; i < num_rqst; i++) {
-		midQ[i] = server->ops->setup_request(ses, &rqst[i]);
+		midQ[i] = server->ops->setup_request(ses, server, &rqst[i]);
 		if (IS_ERR(midQ[i])) {
 			revert_current_mid(server, i);
 			for (j = 0; j < i; j++)
-- 
2.16.4


^ permalink raw reply	[flat|nested] 4+ messages in thread

* [WIP v3] multichannel
  2019-09-17 22:14 [WIP] multichannel Aurelien Aptel
@ 2019-09-17 23:51 ` Aurelien Aptel
  2019-09-18  2:44   ` Steve French
  0 siblings, 1 reply; 4+ messages in thread
From: Aurelien Aptel @ 2019-09-17 23:51 UTC (permalink / raw)
  To: linux-cifs; +Cc: smfrench, Aurelien Aptel

WIP WIP WIP WIP WIP WIP

to test, mount server with multiple interface with

    -o vers=3.11,multichannel,max_channels=3

WIP WIP WIP WIP WIP WIP

changes since last version:
- reuse client guid from master tcp connection
- now works against samba & windows server

Signed-off-by: Aurelien Aptel <aaptel@suse.com>
---
 fs/cifs/cifs_debug.c    |   6 +-
 fs/cifs/cifs_spnego.c   |   2 +-
 fs/cifs/cifsglob.h      |  30 ++++++-
 fs/cifs/cifsproto.h     |   8 ++
 fs/cifs/connect.c       |  84 +++++++++++++++----
 fs/cifs/sess.c          | 216 +++++++++++++++++++++++++++++++++++++++++++++++-
 fs/cifs/smb2misc.c      |  37 ++++++---
 fs/cifs/smb2ops.c       |  13 ++-
 fs/cifs/smb2pdu.c       | 106 ++++++++++++++----------
 fs/cifs/smb2proto.h     |   3 +-
 fs/cifs/smb2transport.c | 162 +++++++++++++++++++++++++++---------
 fs/cifs/transport.c     |  14 +++-
 12 files changed, 562 insertions(+), 119 deletions(-)

diff --git a/fs/cifs/cifs_debug.c b/fs/cifs/cifs_debug.c
index 0b4eee3bed66..ef454170f37d 100644
--- a/fs/cifs/cifs_debug.c
+++ b/fs/cifs/cifs_debug.c
@@ -410,8 +410,12 @@ static int cifs_debug_data_proc_show(struct seq_file *m, void *v)
 				seq_printf(m, "\n\tServer interfaces: %zu\n",
 					   ses->iface_count);
 			for (j = 0; j < ses->iface_count; j++) {
+				struct cifs_server_iface *iface;
+				iface = &ses->iface_list[j];
 				seq_printf(m, "\t%d)", j);
-				cifs_dump_iface(m, &ses->iface_list[j]);
+				cifs_dump_iface(m, iface);
+				if (is_ses_using_iface(ses, iface))
+					seq_puts(m, "\t\t[CONNECTED]\n");
 			}
 			spin_unlock(&ses->iface_lock);
 		}
diff --git a/fs/cifs/cifs_spnego.c b/fs/cifs/cifs_spnego.c
index 7f01c6e60791..7b9b876b513b 100644
--- a/fs/cifs/cifs_spnego.c
+++ b/fs/cifs/cifs_spnego.c
@@ -98,7 +98,7 @@ struct key_type cifs_spnego_key_type = {
 struct key *
 cifs_get_spnego_key(struct cifs_ses *sesInfo)
 {
-	struct TCP_Server_Info *server = sesInfo->server;
+	struct TCP_Server_Info *server = cifs_ses_server(sesInfo);
 	struct sockaddr_in *sa = (struct sockaddr_in *) &server->dstaddr;
 	struct sockaddr_in6 *sa6 = (struct sockaddr_in6 *) &server->dstaddr;
 	char *description, *dp;
diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 54e204589cb9..441970293697 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -230,7 +230,8 @@ struct smb_version_operations {
 	bool (*compare_fids)(struct cifsFileInfo *, struct cifsFileInfo *);
 	/* setup request: allocate mid, sign message */
 	struct mid_q_entry *(*setup_request)(struct cifs_ses *,
-						struct smb_rqst *);
+					     struct TCP_Server_Info *,
+					     struct smb_rqst *);
 	/* setup async request: allocate mid, sign message */
 	struct mid_q_entry *(*setup_async_request)(struct TCP_Server_Info *,
 						struct smb_rqst *);
@@ -590,6 +591,9 @@ struct smb_vol {
 	bool resilient:1; /* noresilient not required since not fored for CA */
 	bool domainauto:1;
 	bool rdma:1;
+	bool multichannel:1;
+	bool use_client_guid:1;
+	u8 client_guid[SMB2_CLIENT_GUID_SIZE]; /* reuse existing guid from master channel */
 	unsigned int bsize;
 	unsigned int rsize;
 	unsigned int wsize;
@@ -606,6 +610,7 @@ struct smb_vol {
 	__u64 snapshot_time; /* needed for timewarp tokens */
 	__u32 handle_timeout; /* persistent and durable handle timeout in ms */
 	unsigned int max_credits; /* smb3 max_credits 10 < credits < 60000 */
+	unsigned int max_channels;
 	__u16 compression; /* compression algorithm 0xFFFF default 0=disabled */
 	bool rootfs:1; /* if it's a SMB root file system */
 };
@@ -952,11 +957,17 @@ struct cifs_server_iface {
 	struct sockaddr_storage sockaddr;
 };
 
+struct cifs_chan {
+	struct TCP_Server_Info *server;
+	__u8 signkey[SMB3_SIGN_KEY_SIZE];
+};
+
 /*
  * Session structure.  One of these for each uid session with a particular host
  */
 struct cifs_ses {
 	struct list_head smb_ses_list;
+	struct list_head chan_ses_list;
 	struct list_head tcon_list;
 	struct cifs_tcon *tcon_ipc;
 	struct mutex session_mutex;
@@ -982,12 +993,15 @@ struct cifs_ses {
 	bool sign;		/* is signing required? */
 	bool need_reconnect:1; /* connection reset, uid now invalid */
 	bool domainAuto:1;
+	bool binding:1; /* are we binding the session? */
 	__u16 session_flags;
 	__u8 smb3signingkey[SMB3_SIGN_KEY_SIZE];
 	__u8 smb3encryptionkey[SMB3_SIGN_KEY_SIZE];
 	__u8 smb3decryptionkey[SMB3_SIGN_KEY_SIZE];
 	__u8 preauth_sha_hash[SMB2_PREAUTH_HASH_SIZE];
 
+	__u8 binding_preauth_sha_hash[SMB2_PREAUTH_HASH_SIZE];
+
 	/*
 	 * Network interfaces available on the server this session is
 	 * connected to.
@@ -1001,8 +1015,22 @@ struct cifs_ses {
 	struct cifs_server_iface *iface_list;
 	size_t iface_count;
 	unsigned long iface_last_update; /* jiffies */
+
+#define CIFS_MAX_CHANNELS 16
+	struct cifs_chan chans[CIFS_MAX_CHANNELS];
+	size_t chan_count;
+	size_t chan_max;
 };
 
+static inline
+struct TCP_Server_Info *cifs_ses_server(struct cifs_ses *ses)
+{
+	if (ses->binding)
+		return ses->chans[ses->chan_count].server;
+	else
+		return ses->server;
+}
+
 static inline bool
 cap_unix(struct cifs_ses *ses)
 {
diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index 99b1b1ef558c..4cda8bba308b 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -109,6 +109,7 @@ extern int SendReceive(const unsigned int /* xid */ , struct cifs_ses *,
 extern int SendReceiveNoRsp(const unsigned int xid, struct cifs_ses *ses,
 			    char *in_buf, int flags);
 extern struct mid_q_entry *cifs_setup_request(struct cifs_ses *,
+				struct TCP_Server_Info *,
 				struct smb_rqst *);
 extern struct mid_q_entry *cifs_setup_async_request(struct TCP_Server_Info *,
 						struct smb_rqst *);
@@ -241,6 +242,7 @@ extern void cifs_add_pending_open_locked(struct cifs_fid *fid,
 					 struct tcon_link *tlink,
 					 struct cifs_pending_open *open);
 extern void cifs_del_pending_open(struct cifs_pending_open *open);
+extern struct TCP_Server_Info *cifs_get_tcp_session(struct smb_vol *vol);
 extern void cifs_put_tcp_session(struct TCP_Server_Info *server,
 				 int from_reconnect);
 extern void cifs_put_tcon(struct cifs_tcon *tcon);
@@ -582,6 +584,12 @@ void cifs_free_hash(struct crypto_shash **shash, struct sdesc **sdesc);
 
 extern void rqst_page_get_length(struct smb_rqst *rqst, unsigned int page,
 				unsigned int *len, unsigned int *offset);
+int cifs_try_adding_channels(struct cifs_ses *ses);
+int cifs_ses_add_channel(struct cifs_ses *ses,
+				struct cifs_server_iface *iface);
+bool is_server_using_iface(struct TCP_Server_Info *server,
+			   struct cifs_server_iface *iface);
+bool is_ses_using_iface(struct cifs_ses *ses, struct cifs_server_iface *iface);
 
 void extract_unc_hostname(const char *unc, const char **h, size_t *len);
 int copy_path_name(char *dst, const char *src);
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 2850c3ce4391..efd9ed46d5d6 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -97,6 +97,7 @@ enum {
 	Opt_persistent, Opt_nopersistent,
 	Opt_resilient, Opt_noresilient,
 	Opt_domainauto, Opt_rdma, Opt_modesid, Opt_rootfs,
+	Opt_multichannel, Opt_nomultichannel,
 	Opt_compress,
 
 	/* Mount options which take numeric value */
@@ -106,7 +107,7 @@ enum {
 	Opt_min_enc_offload,
 	Opt_blocksize, Opt_rsize, Opt_wsize, Opt_actimeo,
 	Opt_echo_interval, Opt_max_credits, Opt_handletimeout,
-	Opt_snapshot,
+	Opt_snapshot, Opt_max_channels,
 
 	/* Mount options which take string value */
 	Opt_user, Opt_pass, Opt_ip,
@@ -199,6 +200,8 @@ static const match_table_t cifs_mount_option_tokens = {
 	{ Opt_noresilient, "noresilienthandles"},
 	{ Opt_domainauto, "domainauto"},
 	{ Opt_rdma, "rdma"},
+	{ Opt_multichannel, "multichannel" },
+	{ Opt_nomultichannel, "nomultichannel" },
 
 	{ Opt_backupuid, "backupuid=%s" },
 	{ Opt_backupgid, "backupgid=%s" },
@@ -218,6 +221,7 @@ static const match_table_t cifs_mount_option_tokens = {
 	{ Opt_echo_interval, "echo_interval=%s" },
 	{ Opt_max_credits, "max_credits=%s" },
 	{ Opt_snapshot, "snapshot=%s" },
+	{ Opt_max_channels, "max_channels=%s" },
 	{ Opt_compress, "compress=%s" },
 
 	{ Opt_blank_user, "user=" },
@@ -1664,6 +1668,10 @@ cifs_parse_mount_options(const char *mountdata, const char *devname,
 
 	vol->echo_interval = SMB_ECHO_INTERVAL_DEFAULT;
 
+	/* default to no multichannel (single server connection) */
+	vol->multichannel = false;
+	vol->max_channels = 1;
+
 	if (!mountdata)
 		goto cifs_parse_mount_err;
 
@@ -1957,6 +1965,12 @@ cifs_parse_mount_options(const char *mountdata, const char *devname,
 		case Opt_rdma:
 			vol->rdma = true;
 			break;
+		case Opt_multichannel:
+			vol->multichannel = true;
+			break;
+		case Opt_nomultichannel:
+			vol->multichannel = false;
+			break;
 		case Opt_compress:
 			vol->compression = UNKNOWN_TYPE;
 			cifs_dbg(VFS,
@@ -2120,6 +2134,15 @@ cifs_parse_mount_options(const char *mountdata, const char *devname,
 			}
 			vol->max_credits = option;
 			break;
+		case Opt_max_channels:
+			if (get_option_ul(args, &option) || option < 1 ||
+				option > CIFS_MAX_CHANNELS) {
+				cifs_dbg(VFS, "%s: Invalid max_channels value, needs to be 1-%d\n",
+					 __func__, CIFS_MAX_CHANNELS);
+				goto cifs_parse_mount_err;
+			}
+			vol->max_channels = option;
+			break;
 
 		/* String Arguments */
 
@@ -2665,6 +2688,7 @@ cifs_put_tcp_session(struct TCP_Server_Info *server, int from_reconnect)
 {
 	struct task_struct *task;
 
+	cifs_dbg(VFS, "XXX server %px", server);
 	spin_lock(&cifs_tcp_ses_lock);
 	if (--server->srv_count > 0) {
 		spin_unlock(&cifs_tcp_ses_lock);
@@ -2705,7 +2729,7 @@ cifs_put_tcp_session(struct TCP_Server_Info *server, int from_reconnect)
 		send_sig(SIGKILL, task, 1);
 }
 
-static struct TCP_Server_Info *
+struct TCP_Server_Info *
 cifs_get_tcp_session(struct smb_vol *volume_info)
 {
 	struct TCP_Server_Info *tcp_ses = NULL;
@@ -2764,7 +2788,10 @@ cifs_get_tcp_session(struct smb_vol *volume_info)
 	       sizeof(tcp_ses->srcaddr));
 	memcpy(&tcp_ses->dstaddr, &volume_info->dstaddr,
 		sizeof(tcp_ses->dstaddr));
-	generate_random_uuid(tcp_ses->client_guid);
+	if (volume_info->use_client_guid)
+		memcpy(tcp_ses->client_guid, volume_info->client_guid, SMB2_CLIENT_GUID_SIZE);
+	else
+		generate_random_uuid(tcp_ses->client_guid);
 	/*
 	 * at this point we are the only ones with the pointer
 	 * to the struct since the kernel thread not created yet
@@ -2853,6 +2880,13 @@ static int match_session(struct cifs_ses *ses, struct smb_vol *vol)
 	    vol->sectype != ses->sectype)
 		return 0;
 
+	/*
+	 * If an existing session is limited to less channels than
+	 * requested, it should not be reused
+	 */
+	if (ses->chan_max < vol->max_channels)
+		return 0;
+
 	switch (ses->sectype) {
 	case Kerberos:
 		if (!uid_eq(vol->cred_uid, ses->cred_uid))
@@ -3269,14 +3303,25 @@ cifs_get_smb_ses(struct TCP_Server_Info *server, struct smb_vol *volume_info)
 	ses->sectype = volume_info->sectype;
 	ses->sign = volume_info->sign;
 	mutex_lock(&ses->session_mutex);
+
+	/* add server as first channel */
+	ses->chans[0].server = server;
+	ses->chan_count = 1;
+	ses->chan_max = volume_info->multichannel ? volume_info->max_channels:1;
+
 	rc = cifs_negotiate_protocol(xid, ses);
 	if (!rc)
 		rc = cifs_setup_session(xid, ses, volume_info->local_nls);
+
+	/* each channel uses a different signing key */
+	memcpy(ses->chans[0].signkey, ses->smb3signingkey,
+	       sizeof(ses->smb3signingkey));
+
 	mutex_unlock(&ses->session_mutex);
 	if (rc)
 		goto get_ses_fail;
 
-	/* success, put it on the list */
+	/* success, put it on the list and add it as first channel */
 	spin_lock(&cifs_tcp_ses_lock);
 	list_add(&ses->smb_ses_list, &server->smb_ses_list);
 	spin_unlock(&cifs_tcp_ses_lock);
@@ -4885,6 +4930,7 @@ int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb_vol *vol)
 	cifs_autodisable_serverino(cifs_sb);
 out:
 	free_xid(xid);
+	cifs_try_adding_channels(ses);
 	return mount_setup_tlink(cifs_sb, ses, tcon);
 
 error:
@@ -5130,7 +5176,7 @@ int
 cifs_negotiate_protocol(const unsigned int xid, struct cifs_ses *ses)
 {
 	int rc = 0;
-	struct TCP_Server_Info *server = ses->server;
+	struct TCP_Server_Info *server = cifs_ses_server(ses);
 
 	if (!server->ops->need_neg || !server->ops->negotiate)
 		return -ENOSYS;
@@ -5157,23 +5203,25 @@ cifs_setup_session(const unsigned int xid, struct cifs_ses *ses,
 		   struct nls_table *nls_info)
 {
 	int rc = -ENOSYS;
-	struct TCP_Server_Info *server = ses->server;
-
-	ses->capabilities = server->capabilities;
-	if (linuxExtEnabled == 0)
-		ses->capabilities &= (~server->vals->cap_unix);
+	struct TCP_Server_Info *server = cifs_ses_server(ses);
+
+	if (!ses->binding) {
+		ses->capabilities = server->capabilities;
+		if (linuxExtEnabled == 0)
+			ses->capabilities &= (~server->vals->cap_unix);
+
+		if (ses->auth_key.response) {
+			cifs_dbg(FYI, "Free previous auth_key.response = %p\n",
+				 ses->auth_key.response);
+			kfree(ses->auth_key.response);
+			ses->auth_key.response = NULL;
+			ses->auth_key.len = 0;
+		}
+	}
 
 	cifs_dbg(FYI, "Security Mode: 0x%x Capabilities: 0x%x TimeAdjust: %d\n",
 		 server->sec_mode, server->capabilities, server->timeAdj);
 
-	if (ses->auth_key.response) {
-		cifs_dbg(FYI, "Free previous auth_key.response = %p\n",
-			 ses->auth_key.response);
-		kfree(ses->auth_key.response);
-		ses->auth_key.response = NULL;
-		ses->auth_key.len = 0;
-	}
-
 	if (server->ops->sess_setup)
 		rc = server->ops->sess_setup(xid, ses, nls_info);
 
diff --git a/fs/cifs/sess.c b/fs/cifs/sess.c
index 4c764ff7edd2..20c73a42755d 100644
--- a/fs/cifs/sess.c
+++ b/fs/cifs/sess.c
@@ -31,6 +31,217 @@
 #include <linux/utsname.h>
 #include <linux/slab.h>
 #include "cifs_spnego.h"
+#include "smb2proto.h"
+
+bool
+is_server_using_iface(struct TCP_Server_Info *server,
+		      struct cifs_server_iface *iface)
+{
+	struct sockaddr_in *i4 = (struct sockaddr_in *)&iface->sockaddr;
+	struct sockaddr_in6 *i6 = (struct sockaddr_in6 *)&iface->sockaddr;
+	struct sockaddr_in *s4 = (struct sockaddr_in *)&server->dstaddr;
+	struct sockaddr_in6 *s6 = (struct sockaddr_in6 *)&server->dstaddr;
+
+	if (server->dstaddr.ss_family != iface->sockaddr.ss_family)
+		return false;
+	if (server->dstaddr.ss_family == AF_INET) {
+		if (s4->sin_addr.s_addr != i4->sin_addr.s_addr)
+			return false;
+	} else if (server->dstaddr.ss_family == AF_INET6) {
+		if (memcmp(&s6->sin6_addr, &i6->sin6_addr,
+			   sizeof(i6->sin6_addr)) != 0)
+			return false;
+	} else {
+		/* unknown family.. */
+		return false;
+	}
+	return true;
+}
+
+bool is_ses_using_iface(struct cifs_ses *ses, struct cifs_server_iface *iface)
+{
+	int i;
+	for (i = 0; i < ses->chan_count; i++) {
+		if (is_server_using_iface(ses->chans[i].server, iface))
+			return true;
+	}
+	return false;
+}
+
+/* returns number of channels added */
+int cifs_try_adding_channels(struct cifs_ses *ses)
+{
+	int old_chan_count = ses->chan_count;
+	int left = ses->chan_max - ses->chan_count;
+	int i = 0;
+	int rc = 0;
+
+	if (left <= 0) {
+		cifs_dbg(FYI,
+			 "ses already at max_channels (%zu), nothing to open\n",
+			 ses->chan_max);
+		return 0;
+	}
+
+	if (ses->server->dialect != SMB311_PROT_ID) {
+		cifs_dbg(VFS, "multichannel is not supported on this protocol version, use 3.1.1\n");
+		return 0;
+	}
+
+	/* ifaces are sorted by speed, try them in order */
+	for (i = 0; left > 0 && i < ses->iface_count; i++) {
+		struct cifs_server_iface *iface;
+
+		iface = &ses->iface_list[i];
+		if (is_ses_using_iface(ses, iface) && !iface->rss_capable)
+			continue;
+
+		rc = cifs_ses_add_channel(ses, iface);
+		if (rc) {
+			cifs_dbg(FYI, "failed to open extra channel\n");
+			continue;
+		}
+
+		cifs_dbg(FYI, "sucessfully opened new channel\n");
+		left--;
+	}
+
+	/*
+	 * TODO: if we still have channels left to open try to connect
+	 * to same RSS-capable iface multiple times
+	 */
+
+	return ses->chan_count - old_chan_count;
+}
+
+int
+cifs_ses_add_channel(struct cifs_ses *ses, struct cifs_server_iface *iface)
+{
+	struct cifs_chan *chan;
+	struct smb_vol vol = {0};
+	const char unc_fmt[] = "\\%s\\foo";
+	char unc[sizeof(unc_fmt)+SERVER_NAME_LEN_WITH_NULL] = {0};
+	struct sockaddr_in *ipv4 = (struct sockaddr_in *)&iface->sockaddr;
+	struct sockaddr_in6 *ipv6 = (struct sockaddr_in6 *)&iface->sockaddr;
+	int rc;
+	unsigned int xid = get_xid();
+
+	cifs_dbg(FYI, "adding channel to ses %p (speed:%zu bps rdma:%s ",
+		 ses, iface->speed, iface->rdma_capable ? "yes" : "no");
+	if (iface->sockaddr.ss_family == AF_INET)
+		cifs_dbg(FYI, "ip:%pI4)\n", &ipv4->sin_addr);
+	else
+		cifs_dbg(FYI, "ip:%pI6)\n", &ipv6->sin6_addr);
+
+	/*
+	 * Setup a smb_vol with mostly the same info as the existing
+	 * session and overwrite it with the requested iface data.
+	 *
+	 * We need to setup at least the fields used for negprot and
+	 * sesssetup.
+	 *
+	 * We only need the volume here, so we can reuse memory from
+	 * the session and server without caring about memory
+	 * management.
+	 */
+
+	/* Always make new connection for now (TODO?) */
+	vol.nosharesock = true;
+
+	/* Auth */
+	vol.domainauto = ses->domainAuto;
+	vol.domainname = ses->domainName;
+	vol.username = ses->user_name;
+	vol.password = ses->password;
+	vol.sectype = ses->sectype;
+	vol.sign = ses->sign;
+
+	/* UNC and paths */
+	/* XXX: Use ses->server->hostname? */
+	sprintf(unc, unc_fmt, ses->serverName);
+	vol.UNC = unc;
+	vol.prepath = "";
+
+	/* Require SMB3.1.1 */
+	vol.vals = &smb311_values;
+	vol.ops = &smb311_operations;
+
+	vol.noblocksnd = ses->server->noblocksnd;
+	vol.noautotune = ses->server->noautotune;
+	vol.sockopt_tcp_nodelay = ses->server->tcp_nodelay;
+	vol.echo_interval = ses->server->echo_interval / HZ;
+
+	/*
+	 * This will be used for encoding/decoding user/domain/pw
+	 * during sess setup auth.
+	 *
+	 * XXX: We use the default for simplicity but the proper way
+	 * would be to use the one that ses used, which is not
+	 * stored. This might break when dealing with non-ascii
+	 * strings.
+	 */
+	vol.local_nls = load_nls_default();
+
+	/* Use RDMA if possible */
+	vol.rdma = iface->rdma_capable;
+	memcpy(&vol.dstaddr, &iface->sockaddr, sizeof(struct sockaddr_storage));
+
+	/* reuse master con client guid */
+	memcpy(&vol.client_guid, ses->server->client_guid, SMB2_CLIENT_GUID_SIZE);
+	vol.use_client_guid = true;
+
+	mutex_lock(&ses->session_mutex);
+
+	chan = &ses->chans[ses->chan_count];
+	chan->server = cifs_get_tcp_session(&vol);
+	if (IS_ERR(chan->server)) {
+		rc = PTR_ERR(chan->server);
+		chan->server = NULL;
+		goto out;
+	}
+
+	/*
+	 * We need to allocate the server crypto now as we will need
+	 * to sign packets before we generate the channel signing key
+	 * (we sign with the session key)
+	 */
+	rc = smb311_crypto_shash_allocate(chan->server);
+	if (rc) {
+		cifs_dbg(VFS, "%s: crypto alloc failed\n", __func__);
+		goto out;
+	}
+
+	ses->binding = true;
+	rc = cifs_negotiate_protocol(xid, ses);
+	if (rc)
+		goto out;
+
+	rc = cifs_setup_session(xid, ses, vol.local_nls);
+	if (rc)
+		goto out;
+
+	/* success, put it on the list
+	 * XXX: sharing ses between 2 tcp server is not possible, the
+	 * way "internal" linked lists works in linux makes element
+	 * only able to belong to one list
+	 *
+	 * the binding session is already established so the rest of
+	 * the code should be able to look it up, no need to add the
+	 * ses to the new server.
+	 */
+
+	ses->chan_count++;
+
+out:
+	ses->binding = false;
+	mutex_unlock(&ses->session_mutex);
+
+	if (rc && chan->server)
+		cifs_put_tcp_session(chan->server, 0);
+	unload_nls(vol.local_nls);
+
+	return rc;
+}
 
 static __u32 cifs_ssetup_hdr(struct cifs_ses *ses, SESSION_SETUP_ANDX *pSMB)
 {
@@ -342,6 +553,7 @@ int decode_ntlmssp_challenge(char *bcc_ptr, int blob_len,
 void build_ntlmssp_negotiate_blob(unsigned char *pbuffer,
 					 struct cifs_ses *ses)
 {
+	struct TCP_Server_Info *server = cifs_ses_server(ses);
 	NEGOTIATE_MESSAGE *sec_blob = (NEGOTIATE_MESSAGE *)pbuffer;
 	__u32 flags;
 
@@ -354,9 +566,9 @@ void build_ntlmssp_negotiate_blob(unsigned char *pbuffer,
 		NTLMSSP_NEGOTIATE_128 | NTLMSSP_NEGOTIATE_UNICODE |
 		NTLMSSP_NEGOTIATE_NTLM | NTLMSSP_NEGOTIATE_EXTENDED_SEC |
 		NTLMSSP_NEGOTIATE_SEAL;
-	if (ses->server->sign)
+	if (server->sign)
 		flags |= NTLMSSP_NEGOTIATE_SIGN;
-	if (!ses->server->session_estab || ses->ntlmssp->sesskey_per_smbsess)
+	if (!server->session_estab || ses->ntlmssp->sesskey_per_smbsess)
 		flags |= NTLMSSP_NEGOTIATE_KEY_XCH;
 
 	sec_blob->NegotiateFlags = cpu_to_le32(flags);
diff --git a/fs/cifs/smb2misc.c b/fs/cifs/smb2misc.c
index e311f58dc1c8..a95ed951c67f 100644
--- a/fs/cifs/smb2misc.c
+++ b/fs/cifs/smb2misc.c
@@ -29,6 +29,7 @@
 #include "cifs_unicode.h"
 #include "smb2status.h"
 #include "smb2glob.h"
+#include "nterr.h"
 
 static int
 check_smb2_hdr(struct smb2_sync_hdr *shdr, __u64 mid)
@@ -788,23 +789,37 @@ smb311_update_preauth_hash(struct cifs_ses *ses, struct kvec *iov, int nvec)
 	int i, rc;
 	struct sdesc *d;
 	struct smb2_sync_hdr *hdr;
+	struct TCP_Server_Info *server = cifs_ses_server(ses);
 
-	if (ses->server->tcpStatus == CifsGood) {
-		/* skip non smb311 connections */
-		if (ses->server->dialect != SMB311_PROT_ID)
-			return 0;
+	hdr = (struct smb2_sync_hdr *)iov[0].iov_base;
+	/* neg prot are always taken */
+	if (hdr->Command == SMB2_NEGOTIATE)
+		goto ok;
 
-		/* skip last sess setup response */
-		hdr = (struct smb2_sync_hdr *)iov[0].iov_base;
-		if (hdr->Flags & SMB2_FLAGS_SIGNED)
-			return 0;
-	}
+	/*
+	 * If we process a command which wasn't a negprot it means the
+	 * neg prot was already done, so the server dialect was set
+	 * and we can test it. Preauth requires 3.1.1 for now.
+	 */
+	if (server->dialect != SMB311_PROT_ID)
+		return 0;
+
+	if (hdr->Command != SMB2_SESSION_SETUP)
+		return 0;
+
+	/* skip last sess setup response */
+	if ((hdr->Flags & SMB2_FLAGS_SERVER_TO_REDIR)
+	    && (hdr->Status == NT_STATUS_OK
+		|| (hdr->Status !=
+		    cpu_to_le32(NT_STATUS_MORE_PROCESSING_REQUIRED))))
+		return 0;
 
-	rc = smb311_crypto_shash_allocate(ses->server);
+ok:
+	rc = smb311_crypto_shash_allocate(server);
 	if (rc)
 		return rc;
 
-	d = ses->server->secmech.sdescsha512;
+	d = server->secmech.sdescsha512;
 	rc = crypto_shash_init(&d->shash);
 	if (rc) {
 		cifs_dbg(VFS, "%s: could not init sha512 shash\n", __func__);
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index eaed18061314..0e66dc1aa1c9 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -10,6 +10,7 @@
 #include <linux/falloc.h>
 #include <linux/scatterlist.h>
 #include <linux/uuid.h>
+#include <linux/sort.h>
 #include <crypto/aead.h>
 #include "cifsglob.h"
 #include "smb2pdu.h"
@@ -315,7 +316,7 @@ smb2_negotiate(const unsigned int xid, struct cifs_ses *ses)
 {
 	int rc;
 
-	ses->server->CurrentMid = 0;
+	cifs_ses_server(ses)->CurrentMid = 0;
 	rc = SMB2_negotiate(xid, ses);
 	/* BB we probably don't need to retry with modern servers */
 	if (rc == -EAGAIN)
@@ -558,6 +559,13 @@ parse_server_interfaces(struct network_interface_info_ioctl_rsp *buf,
 	return rc;
 }
 
+static int compare_iface(const void *ia, const void *ib)
+{
+	const struct cifs_server_iface *a = (struct cifs_server_iface *)ia;
+	const struct cifs_server_iface *b = (struct cifs_server_iface *)ib;
+
+	return a->speed == b->speed ? 0 : (a->speed > b->speed ? -1 : 1);
+}
 
 static int
 SMB3_request_interfaces(const unsigned int xid, struct cifs_tcon *tcon)
@@ -587,6 +595,9 @@ SMB3_request_interfaces(const unsigned int xid, struct cifs_tcon *tcon)
 	if (rc)
 		goto out;
 
+	/* sort interfaces from fastest to slowest */
+	sort(iface_list, iface_count, sizeof(*iface_list), compare_iface, NULL);
+
 	spin_lock(&ses->iface_lock);
 	kfree(ses->iface_list);
 	ses->iface_list = iface_list;
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 87066f1af12c..8bcb278fdb0a 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -789,7 +789,7 @@ SMB2_negotiate(const unsigned int xid, struct cifs_ses *ses)
 	struct kvec rsp_iov;
 	int rc = 0;
 	int resp_buftype;
-	struct TCP_Server_Info *server = ses->server;
+	struct TCP_Server_Info *server = cifs_ses_server(ses);
 	int blob_offset, blob_length;
 	char *security_blob;
 	int flags = CIFS_NEG_OP;
@@ -811,7 +811,7 @@ SMB2_negotiate(const unsigned int xid, struct cifs_ses *ses)
 	memset(server->preauth_sha_hash, 0, SMB2_PREAUTH_HASH_SIZE);
 	memset(ses->preauth_sha_hash, 0, SMB2_PREAUTH_HASH_SIZE);
 
-	if (strcmp(ses->server->vals->version_string,
+	if (strcmp(server->vals->version_string,
 		   SMB3ANY_VERSION_STRING) == 0) {
 		req->Dialects[0] = cpu_to_le16(SMB30_PROT_ID);
 		req->Dialects[1] = cpu_to_le16(SMB302_PROT_ID);
@@ -827,7 +827,7 @@ SMB2_negotiate(const unsigned int xid, struct cifs_ses *ses)
 		total_len += 8;
 	} else {
 		/* otherwise send specific dialect */
-		req->Dialects[0] = cpu_to_le16(ses->server->vals->protocol_id);
+		req->Dialects[0] = cpu_to_le16(server->vals->protocol_id);
 		req->DialectCount = cpu_to_le16(1);
 		total_len += 2;
 	}
@@ -1169,7 +1169,7 @@ SMB2_sess_alloc_buffer(struct SMB2_sess_data *sess_data)
 	int rc;
 	struct cifs_ses *ses = sess_data->ses;
 	struct smb2_sess_setup_req *req;
-	struct TCP_Server_Info *server = ses->server;
+	struct TCP_Server_Info *server = cifs_ses_server(ses);
 	unsigned int total_len;
 
 	rc = smb2_plain_req_init(SMB2_SESSION_SETUP, NULL, (void **) &req,
@@ -1177,13 +1177,18 @@ SMB2_sess_alloc_buffer(struct SMB2_sess_data *sess_data)
 	if (rc)
 		return rc;
 
-	/* First session, not a reauthenticate */
-	req->sync_hdr.SessionId = 0;
-
-	/* if reconnect, we need to send previous sess id, otherwise it is 0 */
-	req->PreviousSessionId = sess_data->previous_session;
-
-	req->Flags = 0; /* MBZ */
+	if (sess_data->ses->binding) {
+		req->sync_hdr.SessionId = sess_data->ses->Suid;
+		req->sync_hdr.Flags |= SMB2_FLAGS_SIGNED;
+		req->PreviousSessionId = 0;
+		req->Flags = SMB2_SESSION_REQ_FLAG_BINDING;
+	} else {
+		/* First session, not a reauthenticate */
+		req->sync_hdr.SessionId = 0;
+		/* if reconnect, we need to send previous sess id, otherwise it is 0 */
+		req->PreviousSessionId = sess_data->previous_session;
+		req->Flags = 0; /* MBZ */
+	}
 
 	/* enough to enable echos and oplocks and one max size write */
 	req->sync_hdr.CreditRequest = cpu_to_le16(130);
@@ -1256,28 +1261,33 @@ SMB2_sess_establish_session(struct SMB2_sess_data *sess_data)
 {
 	int rc = 0;
 	struct cifs_ses *ses = sess_data->ses;
+	struct TCP_Server_Info *server = cifs_ses_server(ses);
 
-	mutex_lock(&ses->server->srv_mutex);
-	if (ses->server->ops->generate_signingkey) {
-		rc = ses->server->ops->generate_signingkey(ses);
+	mutex_lock(&server->srv_mutex);
+	if (server->ops->generate_signingkey) {
+		rc = server->ops->generate_signingkey(ses);
 		if (rc) {
 			cifs_dbg(FYI,
 				"SMB3 session key generation failed\n");
-			mutex_unlock(&ses->server->srv_mutex);
+			mutex_unlock(&server->srv_mutex);
 			return rc;
 		}
 	}
-	if (!ses->server->session_estab) {
-		ses->server->sequence_number = 0x2;
-		ses->server->session_estab = true;
+	if (!server->session_estab) {
+		server->sequence_number = 0x2;
+		server->session_estab = true;
 	}
-	mutex_unlock(&ses->server->srv_mutex);
+	mutex_unlock(&server->srv_mutex);
 
 	cifs_dbg(FYI, "SMB2/3 session established successfully\n");
-	spin_lock(&GlobalMid_Lock);
-	ses->status = CifsGood;
-	ses->need_reconnect = false;
-	spin_unlock(&GlobalMid_Lock);
+	/* keep exising ses state if binding */
+	if (!ses->binding) {
+		spin_lock(&GlobalMid_Lock);
+		ses->status = CifsGood;
+		ses->need_reconnect = false;
+		spin_unlock(&GlobalMid_Lock);
+	}
+
 	return rc;
 }
 
@@ -1315,16 +1325,19 @@ SMB2_auth_kerberos(struct SMB2_sess_data *sess_data)
 		goto out_put_spnego_key;
 	}
 
-	ses->auth_key.response = kmemdup(msg->data, msg->sesskey_len,
-					 GFP_KERNEL);
-	if (!ses->auth_key.response) {
-		cifs_dbg(VFS,
-			"Kerberos can't allocate (%u bytes) memory",
-			msg->sesskey_len);
-		rc = -ENOMEM;
-		goto out_put_spnego_key;
+	/* keep session key if binding */
+	if (!ses->binding) {
+		ses->auth_key.response = kmemdup(msg->data, msg->sesskey_len,
+						 GFP_KERNEL);
+		if (!ses->auth_key.response) {
+			cifs_dbg(VFS,
+				 "Kerberos can't allocate (%u bytes) memory",
+				 msg->sesskey_len);
+			rc = -ENOMEM;
+			goto out_put_spnego_key;
+		}
+		ses->auth_key.len = msg->sesskey_len;
 	}
-	ses->auth_key.len = msg->sesskey_len;
 
 	sess_data->iov[1].iov_base = msg->data + msg->sesskey_len;
 	sess_data->iov[1].iov_len = msg->secblob_len;
@@ -1334,9 +1347,11 @@ SMB2_auth_kerberos(struct SMB2_sess_data *sess_data)
 		goto out_put_spnego_key;
 
 	rsp = (struct smb2_sess_setup_rsp *)sess_data->iov[0].iov_base;
-	ses->Suid = rsp->sync_hdr.SessionId;
-
-	ses->session_flags = le16_to_cpu(rsp->SessionFlags);
+	/* keep session id and flags if binding */
+	if (!ses->binding) {
+		ses->Suid = rsp->sync_hdr.SessionId;
+		ses->session_flags = le16_to_cpu(rsp->SessionFlags);
+	}
 
 	rc = SMB2_sess_establish_session(sess_data);
 out_put_spnego_key:
@@ -1430,9 +1445,11 @@ SMB2_sess_auth_rawntlmssp_negotiate(struct SMB2_sess_data *sess_data)
 
 	cifs_dbg(FYI, "rawntlmssp session setup challenge phase\n");
 
-
-	ses->Suid = rsp->sync_hdr.SessionId;
-	ses->session_flags = le16_to_cpu(rsp->SessionFlags);
+	/* keep existing ses id and flags if binding */
+	if (!ses->binding) {
+		ses->Suid = rsp->sync_hdr.SessionId;
+		ses->session_flags = le16_to_cpu(rsp->SessionFlags);
+	}
 
 out:
 	kfree(ntlmssp_blob);
@@ -1489,8 +1506,11 @@ SMB2_sess_auth_rawntlmssp_authenticate(struct SMB2_sess_data *sess_data)
 
 	rsp = (struct smb2_sess_setup_rsp *)sess_data->iov[0].iov_base;
 
-	ses->Suid = rsp->sync_hdr.SessionId;
-	ses->session_flags = le16_to_cpu(rsp->SessionFlags);
+	/* keep existing ses id and flags if binding */
+	if (!ses->binding) {
+		ses->Suid = rsp->sync_hdr.SessionId;
+		ses->session_flags = le16_to_cpu(rsp->SessionFlags);
+	}
 
 	rc = SMB2_sess_establish_session(sess_data);
 out:
@@ -1507,7 +1527,7 @@ SMB2_select_sec(struct cifs_ses *ses, struct SMB2_sess_data *sess_data)
 {
 	int type;
 
-	type = smb2_select_sectype(ses->server, ses->sectype);
+	type = smb2_select_sectype(cifs_ses_server(ses), ses->sectype);
 	cifs_dbg(FYI, "sess setup type %d\n", type);
 	if (type == Unspecified) {
 		cifs_dbg(VFS,
@@ -1535,7 +1555,7 @@ SMB2_sess_setup(const unsigned int xid, struct cifs_ses *ses,
 		const struct nls_table *nls_cp)
 {
 	int rc = 0;
-	struct TCP_Server_Info *server = ses->server;
+	struct TCP_Server_Info *server = cifs_ses_server(ses);
 	struct SMB2_sess_data *sess_data;
 
 	cifs_dbg(FYI, "Session Setup\n");
@@ -1561,7 +1581,7 @@ SMB2_sess_setup(const unsigned int xid, struct cifs_ses *ses,
 	/*
 	 * Initialize the session hash with the server one.
 	 */
-	memcpy(ses->preauth_sha_hash, ses->server->preauth_sha_hash,
+	memcpy(ses->preauth_sha_hash, server->preauth_sha_hash,
 	       SMB2_PREAUTH_HASH_SIZE);
 
 	while (sess_data->func)
diff --git a/fs/cifs/smb2proto.h b/fs/cifs/smb2proto.h
index 67a91b11fd59..804b6dc5546b 100644
--- a/fs/cifs/smb2proto.h
+++ b/fs/cifs/smb2proto.h
@@ -46,7 +46,8 @@ extern int smb2_verify_signature(struct smb_rqst *, struct TCP_Server_Info *);
 extern int smb2_check_receive(struct mid_q_entry *mid,
 			      struct TCP_Server_Info *server, bool log_error);
 extern struct mid_q_entry *smb2_setup_request(struct cifs_ses *ses,
-			      struct smb_rqst *rqst);
+					      struct TCP_Server_Info *,
+					      struct smb_rqst *rqst);
 extern struct mid_q_entry *smb2_setup_async_request(
 			struct TCP_Server_Info *server, struct smb_rqst *rqst);
 extern struct cifs_ses *smb2_find_smb_ses(struct TCP_Server_Info *server,
diff --git a/fs/cifs/smb2transport.c b/fs/cifs/smb2transport.c
index 148d7942c796..539cf2fc1f3b 100644
--- a/fs/cifs/smb2transport.c
+++ b/fs/cifs/smb2transport.c
@@ -48,7 +48,7 @@ smb2_crypto_shash_allocate(struct TCP_Server_Info *server)
 			       &server->secmech.sdeschmacsha256);
 }
 
-static int
+int
 smb3_crypto_shash_allocate(struct TCP_Server_Info *server)
 {
 	struct cifs_secmech *p = &server->secmech;
@@ -98,6 +98,47 @@ smb311_crypto_shash_allocate(struct TCP_Server_Info *server)
 	return rc;
 }
 
+u8 *smb2_find_chan_signkey(struct cifs_ses *ses, struct TCP_Server_Info *server)
+{
+	int i;
+	struct cifs_chan *chan;
+	int count;
+	spin_lock(&cifs_tcp_ses_lock);
+	count = ses->chan_count;
+	if (ses->binding)
+		count++;
+	for (i = 0; i < count; i++) {
+		chan = ses->chans + i;
+		if (chan->server == server) {
+			spin_unlock(&cifs_tcp_ses_lock);
+			return chan->signkey;
+		}
+	}
+	spin_unlock(&cifs_tcp_ses_lock);
+	return NULL;
+}
+
+struct cifs_ses *
+smb2_find_global_smb_ses(__u64 ses_id)
+{
+	struct TCP_Server_Info *server;
+	struct cifs_ses *ses;
+	cifs_dbg(VFS, "XXX: searching for sesid %llu", ses_id);
+	spin_lock(&cifs_tcp_ses_lock);
+	list_for_each_entry(server, &cifs_tcp_ses_list, tcp_ses_list) {
+		cifs_dbg(VFS, "XXX: server %px ", server);
+		list_for_each_entry(ses, &server->smb_ses_list, smb_ses_list) {
+			cifs_dbg(VFS, "XXX: ses %px ", ses);
+			if (ses->Suid == ses_id) {
+				spin_unlock(&cifs_tcp_ses_lock);
+				return ses;
+			}
+		}
+	}
+	spin_unlock(&cifs_tcp_ses_lock);
+	return NULL;
+}
+
 static struct cifs_ses *
 smb2_find_smb_ses_unlocked(struct TCP_Server_Info *server, __u64 ses_id)
 {
@@ -328,21 +369,34 @@ generate_smb3signingkey(struct cifs_ses *ses,
 {
 	int rc;
 
-	rc = generate_key(ses, ptriplet->signing.label,
-			  ptriplet->signing.context, ses->smb3signingkey,
-			  SMB3_SIGN_KEY_SIZE);
-	if (rc)
-		return rc;
-
-	rc = generate_key(ses, ptriplet->encryption.label,
-			  ptriplet->encryption.context, ses->smb3encryptionkey,
-			  SMB3_SIGN_KEY_SIZE);
-	if (rc)
-		return rc;
-
-	rc = generate_key(ses, ptriplet->decryption.label,
-			  ptriplet->decryption.context,
-			  ses->smb3decryptionkey, SMB3_SIGN_KEY_SIZE);
+	if (ses->binding) {
+		struct TCP_Server_Info *server;
+		cifs_dbg(VFS, "XXX: BINDING! gen signkey");
+		server = cifs_ses_server(ses);
+		rc = generate_key(ses, ptriplet->signing.label,
+				  ptriplet->signing.context,
+				  smb2_find_chan_signkey(ses, server),
+				  SMB3_SIGN_KEY_SIZE);
+		if (rc)
+			return rc;
+	} else {
+		rc = generate_key(ses, ptriplet->signing.label,
+				  ptriplet->signing.context,
+				  ses->smb3signingkey,
+				  SMB3_SIGN_KEY_SIZE);
+		if (rc)
+			return rc;
+		rc = generate_key(ses, ptriplet->encryption.label,
+				  ptriplet->encryption.context,
+				  ses->smb3encryptionkey,
+				  SMB3_SIGN_KEY_SIZE);
+		rc = generate_key(ses, ptriplet->decryption.label,
+				  ptriplet->decryption.context,
+				  ses->smb3decryptionkey,
+				  SMB3_SIGN_KEY_SIZE);
+		if (rc)
+			return rc;
+	}
 
 	if (rc)
 		return rc;
@@ -434,18 +488,35 @@ smb3_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
 	struct cifs_ses *ses;
 	struct shash_desc *shash = &server->secmech.sdesccmacaes->shash;
 	struct smb_rqst drqst;
+	u8 *key;
 
-	ses = smb2_find_smb_ses(server, shdr->SessionId);
+	ses = smb2_find_global_smb_ses(shdr->SessionId);
 	if (!ses) {
 		cifs_server_dbg(VFS, "%s: Could not find session\n", __func__);
 		return 0;
 	}
 
+	/*
+	 * If we are binding an existing session use the session key,
+	 * otherwise use the channel key
+	 */
+	if (ses->binding) {
+		key = ses->smb3signingkey;
+		cifs_dbg(VFS, "XXX: using bind ses key %px", key);
+	} else {
+		key = smb2_find_chan_signkey(ses, server);
+		cifs_dbg(VFS, "XXX: using chan ses key %px", key);
+		if (!key) {
+			cifs_dbg(VFS, "XXX: could not find channel key");
+			return 0;
+		}
+        }
+
 	memset(smb3_signature, 0x0, SMB2_CMACAES_SIZE);
 	memset(shdr->Signature, 0x0, SMB2_SIGNATURE_SIZE);
 
 	rc = crypto_shash_setkey(server->secmech.cmacaes,
-				 ses->smb3signingkey, SMB2_CMACAES_SIZE);
+				 key, SMB2_CMACAES_SIZE);
 	if (rc) {
 		cifs_server_dbg(VFS, "%s: Could not set key for cmac aes\n", __func__);
 		return rc;
@@ -494,18 +565,35 @@ static int
 smb2_sign_rqst(struct smb_rqst *rqst, struct TCP_Server_Info *server)
 {
 	int rc = 0;
-	struct smb2_sync_hdr *shdr =
-			(struct smb2_sync_hdr *)rqst->rq_iov[0].iov_base;
+	struct smb2_sync_hdr *shdr;
+	struct smb2_sess_setup_req *ssr;
+	bool is_binding;
+	bool is_signed;
 
-	if (!(shdr->Flags & SMB2_FLAGS_SIGNED) ||
-	    server->tcpStatus == CifsNeedNegotiate)
-		return rc;
+	shdr = (struct smb2_sync_hdr *)rqst->rq_iov[0].iov_base;
+	ssr = (struct smb2_sess_setup_req *)shdr;
 
-	if (!server->session_estab) {
+	is_binding = shdr->Command == SMB2_SESSION_SETUP &&
+		(ssr->Flags & SMB2_SESSION_REQ_FLAG_BINDING);
+	is_signed = shdr->Flags & SMB2_FLAGS_SIGNED;
+
+	printk(KERN_WARNING "XXX: sign_rqst\n");
+
+	if (!is_signed) {
+		printk(KERN_WARNING "XXX: no signed flag\n");
+		return 0;
+	}
+	if (server->tcpStatus == CifsNeedNegotiate) {
+		printk(KERN_WARNING "XXX: need nego\n");
+		return 0;
+	}
+	if (!is_binding && !server->session_estab) {
 		strncpy(shdr->Signature, "BSRSPYL", 8);
-		return rc;
+		printk(KERN_WARNING "XXX: !session_estab\n");
+		return 0;
 	}
 
+	printk(KERN_WARNING "XXX: actually signing!\n");
 	rc = server->ops->calc_signature(rqst, server);
 
 	return rc;
@@ -610,18 +698,18 @@ smb2_mid_entry_alloc(const struct smb2_sync_hdr *shdr,
 }
 
 static int
-smb2_get_mid_entry(struct cifs_ses *ses, struct smb2_sync_hdr *shdr,
+smb2_get_mid_entry(struct cifs_ses *ses, struct TCP_Server_Info *server, struct smb2_sync_hdr *shdr,
 		   struct mid_q_entry **mid)
 {
-	if (ses->server->tcpStatus == CifsExiting)
+	if (server->tcpStatus == CifsExiting)
 		return -ENOENT;
 
-	if (ses->server->tcpStatus == CifsNeedReconnect) {
+	if (server->tcpStatus == CifsNeedReconnect) {
 		cifs_dbg(FYI, "tcp session dead - return to caller to retry\n");
 		return -EAGAIN;
 	}
 
-	if (ses->server->tcpStatus == CifsNeedNegotiate &&
+	if (server->tcpStatus == CifsNeedNegotiate &&
 	   shdr->Command != SMB2_NEGOTIATE)
 		return -EAGAIN;
 
@@ -638,11 +726,11 @@ smb2_get_mid_entry(struct cifs_ses *ses, struct smb2_sync_hdr *shdr,
 		/* else ok - we are shutting down the session */
 	}
 
-	*mid = smb2_mid_entry_alloc(shdr, ses->server);
+	*mid = smb2_mid_entry_alloc(shdr, server);
 	if (*mid == NULL)
 		return -ENOMEM;
 	spin_lock(&GlobalMid_Lock);
-	list_add_tail(&(*mid)->qhead, &ses->server->pending_mid_q);
+	list_add_tail(&(*mid)->qhead, &server->pending_mid_q);
 	spin_unlock(&GlobalMid_Lock);
 
 	return 0;
@@ -675,24 +763,24 @@ smb2_check_receive(struct mid_q_entry *mid, struct TCP_Server_Info *server,
 }
 
 struct mid_q_entry *
-smb2_setup_request(struct cifs_ses *ses, struct smb_rqst *rqst)
+smb2_setup_request(struct cifs_ses *ses, struct TCP_Server_Info *server, struct smb_rqst *rqst)
 {
 	int rc;
 	struct smb2_sync_hdr *shdr =
 			(struct smb2_sync_hdr *)rqst->rq_iov[0].iov_base;
 	struct mid_q_entry *mid;
 
-	smb2_seq_num_into_buf(ses->server, shdr);
+	smb2_seq_num_into_buf(server, shdr);
 
-	rc = smb2_get_mid_entry(ses, shdr, &mid);
+	rc = smb2_get_mid_entry(ses, server, shdr, &mid);
 	if (rc) {
-		revert_current_mid_from_hdr(ses->server, shdr);
+		revert_current_mid_from_hdr(server, shdr);
 		return ERR_PTR(rc);
 	}
 
-	rc = smb2_sign_rqst(rqst, ses->server);
+	rc = smb2_sign_rqst(rqst, server);
 	if (rc) {
-		revert_current_mid_from_hdr(ses->server, shdr);
+		revert_current_mid_from_hdr(server, shdr);
 		cifs_delete_mid(mid);
 		return ERR_PTR(rc);
 	}
diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
index 308ad0f495e1..a4c2d62ee437 100644
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -923,7 +923,7 @@ cifs_check_receive(struct mid_q_entry *mid, struct TCP_Server_Info *server,
 }
 
 struct mid_q_entry *
-cifs_setup_request(struct cifs_ses *ses, struct smb_rqst *rqst)
+cifs_setup_request(struct cifs_ses *ses, struct TCP_Server_Info *ignored, struct smb_rqst *rqst)
 {
 	int rc;
 	struct smb_hdr *hdr = (struct smb_hdr *)rqst->rq_iov[0].iov_base;
@@ -995,7 +995,15 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
 		return -EIO;
 	}
 
-	server = ses->server;
+	if (!ses->binding) {
+		uint index = ((unsigned)get_random_int()) % ses->chan_count;
+		cifs_dbg(VFS, "XXX: send/recv: using random channel %d", index);
+		server = ses->chans[index].server;
+	} else {
+		cifs_dbg(VFS, "XXX: send/recv: binding, using last serv");
+		server = cifs_ses_server(ses);
+	}
+
 	if (server->tcpStatus == CifsExiting)
 		return -ENOENT;
 
@@ -1040,7 +1048,7 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
 	}
 
 	for (i = 0; i < num_rqst; i++) {
-		midQ[i] = server->ops->setup_request(ses, &rqst[i]);
+		midQ[i] = server->ops->setup_request(ses, server, &rqst[i]);
 		if (IS_ERR(midQ[i])) {
 			revert_current_mid(server, i);
 			for (j = 0; j < i; j++)
-- 
2.16.4


^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [WIP v3] multichannel
  2019-09-17 23:51 ` [WIP v3] multichannel Aurelien Aptel
@ 2019-09-18  2:44   ` Steve French
  0 siblings, 0 replies; 4+ messages in thread
From: Steve French @ 2019-09-18  2:44 UTC (permalink / raw)
  To: Aurelien Aptel; +Cc: CIFS

Checkpatch had a few minor indentation complaints and then probably a
valid one about not using %px and these two as well:

WARNING: Prefer 'unsigned int' to bare use of 'unsigned'
#1245: FILE: fs/cifs/transport.c:999:
+        uint index = ((unsigned)get_random_int()) % ses->chan_count;

WARNING: Missing a blank line after declarations
#1246: FILE: fs/cifs/transport.c:1000:
+        uint index = ((unsigned)get_random_int()) % ses->chan_count;
+        cifs_dbg(VFS, "XXX: send/recv: using random channel %d", index);

On Tue, Sep 17, 2019 at 6:51 PM Aurelien Aptel <aaptel@suse.com> wrote:
>
> WIP WIP WIP WIP WIP WIP
>
> to test, mount server with multiple interface with
>
>     -o vers=3.11,multichannel,max_channels=3
>
> WIP WIP WIP WIP WIP WIP
>
> changes since last version:
> - reuse client guid from master tcp connection
> - now works against samba & windows server
>
> Signed-off-by: Aurelien Aptel <aaptel@suse.com>
> ---
>  fs/cifs/cifs_debug.c    |   6 +-
>  fs/cifs/cifs_spnego.c   |   2 +-
>  fs/cifs/cifsglob.h      |  30 ++++++-
>  fs/cifs/cifsproto.h     |   8 ++
>  fs/cifs/connect.c       |  84 +++++++++++++++----
>  fs/cifs/sess.c          | 216 +++++++++++++++++++++++++++++++++++++++++++++++-
>  fs/cifs/smb2misc.c      |  37 ++++++---
>  fs/cifs/smb2ops.c       |  13 ++-
>  fs/cifs/smb2pdu.c       | 106 ++++++++++++++----------
>  fs/cifs/smb2proto.h     |   3 +-
>  fs/cifs/smb2transport.c | 162 +++++++++++++++++++++++++++---------
>  fs/cifs/transport.c     |  14 +++-
>  12 files changed, 562 insertions(+), 119 deletions(-)
>
> diff --git a/fs/cifs/cifs_debug.c b/fs/cifs/cifs_debug.c
> index 0b4eee3bed66..ef454170f37d 100644
> --- a/fs/cifs/cifs_debug.c
> +++ b/fs/cifs/cifs_debug.c
> @@ -410,8 +410,12 @@ static int cifs_debug_data_proc_show(struct seq_file *m, void *v)
>                                 seq_printf(m, "\n\tServer interfaces: %zu\n",
>                                            ses->iface_count);
>                         for (j = 0; j < ses->iface_count; j++) {
> +                               struct cifs_server_iface *iface;
> +                               iface = &ses->iface_list[j];
>                                 seq_printf(m, "\t%d)", j);
> -                               cifs_dump_iface(m, &ses->iface_list[j]);
> +                               cifs_dump_iface(m, iface);
> +                               if (is_ses_using_iface(ses, iface))
> +                                       seq_puts(m, "\t\t[CONNECTED]\n");
>                         }
>                         spin_unlock(&ses->iface_lock);
>                 }
> diff --git a/fs/cifs/cifs_spnego.c b/fs/cifs/cifs_spnego.c
> index 7f01c6e60791..7b9b876b513b 100644
> --- a/fs/cifs/cifs_spnego.c
> +++ b/fs/cifs/cifs_spnego.c
> @@ -98,7 +98,7 @@ struct key_type cifs_spnego_key_type = {
>  struct key *
>  cifs_get_spnego_key(struct cifs_ses *sesInfo)
>  {
> -       struct TCP_Server_Info *server = sesInfo->server;
> +       struct TCP_Server_Info *server = cifs_ses_server(sesInfo);
>         struct sockaddr_in *sa = (struct sockaddr_in *) &server->dstaddr;
>         struct sockaddr_in6 *sa6 = (struct sockaddr_in6 *) &server->dstaddr;
>         char *description, *dp;
> diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
> index 54e204589cb9..441970293697 100644
> --- a/fs/cifs/cifsglob.h
> +++ b/fs/cifs/cifsglob.h
> @@ -230,7 +230,8 @@ struct smb_version_operations {
>         bool (*compare_fids)(struct cifsFileInfo *, struct cifsFileInfo *);
>         /* setup request: allocate mid, sign message */
>         struct mid_q_entry *(*setup_request)(struct cifs_ses *,
> -                                               struct smb_rqst *);
> +                                            struct TCP_Server_Info *,
> +                                            struct smb_rqst *);
>         /* setup async request: allocate mid, sign message */
>         struct mid_q_entry *(*setup_async_request)(struct TCP_Server_Info *,
>                                                 struct smb_rqst *);
> @@ -590,6 +591,9 @@ struct smb_vol {
>         bool resilient:1; /* noresilient not required since not fored for CA */
>         bool domainauto:1;
>         bool rdma:1;
> +       bool multichannel:1;
> +       bool use_client_guid:1;
> +       u8 client_guid[SMB2_CLIENT_GUID_SIZE]; /* reuse existing guid from master channel */
>         unsigned int bsize;
>         unsigned int rsize;
>         unsigned int wsize;
> @@ -606,6 +610,7 @@ struct smb_vol {
>         __u64 snapshot_time; /* needed for timewarp tokens */
>         __u32 handle_timeout; /* persistent and durable handle timeout in ms */
>         unsigned int max_credits; /* smb3 max_credits 10 < credits < 60000 */
> +       unsigned int max_channels;
>         __u16 compression; /* compression algorithm 0xFFFF default 0=disabled */
>         bool rootfs:1; /* if it's a SMB root file system */
>  };
> @@ -952,11 +957,17 @@ struct cifs_server_iface {
>         struct sockaddr_storage sockaddr;
>  };
>
> +struct cifs_chan {
> +       struct TCP_Server_Info *server;
> +       __u8 signkey[SMB3_SIGN_KEY_SIZE];
> +};
> +
>  /*
>   * Session structure.  One of these for each uid session with a particular host
>   */
>  struct cifs_ses {
>         struct list_head smb_ses_list;
> +       struct list_head chan_ses_list;
>         struct list_head tcon_list;
>         struct cifs_tcon *tcon_ipc;
>         struct mutex session_mutex;
> @@ -982,12 +993,15 @@ struct cifs_ses {
>         bool sign;              /* is signing required? */
>         bool need_reconnect:1; /* connection reset, uid now invalid */
>         bool domainAuto:1;
> +       bool binding:1; /* are we binding the session? */
>         __u16 session_flags;
>         __u8 smb3signingkey[SMB3_SIGN_KEY_SIZE];
>         __u8 smb3encryptionkey[SMB3_SIGN_KEY_SIZE];
>         __u8 smb3decryptionkey[SMB3_SIGN_KEY_SIZE];
>         __u8 preauth_sha_hash[SMB2_PREAUTH_HASH_SIZE];
>
> +       __u8 binding_preauth_sha_hash[SMB2_PREAUTH_HASH_SIZE];
> +
>         /*
>          * Network interfaces available on the server this session is
>          * connected to.
> @@ -1001,8 +1015,22 @@ struct cifs_ses {
>         struct cifs_server_iface *iface_list;
>         size_t iface_count;
>         unsigned long iface_last_update; /* jiffies */
> +
> +#define CIFS_MAX_CHANNELS 16
> +       struct cifs_chan chans[CIFS_MAX_CHANNELS];
> +       size_t chan_count;
> +       size_t chan_max;
>  };
>
> +static inline
> +struct TCP_Server_Info *cifs_ses_server(struct cifs_ses *ses)
> +{
> +       if (ses->binding)
> +               return ses->chans[ses->chan_count].server;
> +       else
> +               return ses->server;
> +}
> +
>  static inline bool
>  cap_unix(struct cifs_ses *ses)
>  {
> diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
> index 99b1b1ef558c..4cda8bba308b 100644
> --- a/fs/cifs/cifsproto.h
> +++ b/fs/cifs/cifsproto.h
> @@ -109,6 +109,7 @@ extern int SendReceive(const unsigned int /* xid */ , struct cifs_ses *,
>  extern int SendReceiveNoRsp(const unsigned int xid, struct cifs_ses *ses,
>                             char *in_buf, int flags);
>  extern struct mid_q_entry *cifs_setup_request(struct cifs_ses *,
> +                               struct TCP_Server_Info *,
>                                 struct smb_rqst *);
>  extern struct mid_q_entry *cifs_setup_async_request(struct TCP_Server_Info *,
>                                                 struct smb_rqst *);
> @@ -241,6 +242,7 @@ extern void cifs_add_pending_open_locked(struct cifs_fid *fid,
>                                          struct tcon_link *tlink,
>                                          struct cifs_pending_open *open);
>  extern void cifs_del_pending_open(struct cifs_pending_open *open);
> +extern struct TCP_Server_Info *cifs_get_tcp_session(struct smb_vol *vol);
>  extern void cifs_put_tcp_session(struct TCP_Server_Info *server,
>                                  int from_reconnect);
>  extern void cifs_put_tcon(struct cifs_tcon *tcon);
> @@ -582,6 +584,12 @@ void cifs_free_hash(struct crypto_shash **shash, struct sdesc **sdesc);
>
>  extern void rqst_page_get_length(struct smb_rqst *rqst, unsigned int page,
>                                 unsigned int *len, unsigned int *offset);
> +int cifs_try_adding_channels(struct cifs_ses *ses);
> +int cifs_ses_add_channel(struct cifs_ses *ses,
> +                               struct cifs_server_iface *iface);
> +bool is_server_using_iface(struct TCP_Server_Info *server,
> +                          struct cifs_server_iface *iface);
> +bool is_ses_using_iface(struct cifs_ses *ses, struct cifs_server_iface *iface);
>
>  void extract_unc_hostname(const char *unc, const char **h, size_t *len);
>  int copy_path_name(char *dst, const char *src);
> diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
> index 2850c3ce4391..efd9ed46d5d6 100644
> --- a/fs/cifs/connect.c
> +++ b/fs/cifs/connect.c
> @@ -97,6 +97,7 @@ enum {
>         Opt_persistent, Opt_nopersistent,
>         Opt_resilient, Opt_noresilient,
>         Opt_domainauto, Opt_rdma, Opt_modesid, Opt_rootfs,
> +       Opt_multichannel, Opt_nomultichannel,
>         Opt_compress,
>
>         /* Mount options which take numeric value */
> @@ -106,7 +107,7 @@ enum {
>         Opt_min_enc_offload,
>         Opt_blocksize, Opt_rsize, Opt_wsize, Opt_actimeo,
>         Opt_echo_interval, Opt_max_credits, Opt_handletimeout,
> -       Opt_snapshot,
> +       Opt_snapshot, Opt_max_channels,
>
>         /* Mount options which take string value */
>         Opt_user, Opt_pass, Opt_ip,
> @@ -199,6 +200,8 @@ static const match_table_t cifs_mount_option_tokens = {
>         { Opt_noresilient, "noresilienthandles"},
>         { Opt_domainauto, "domainauto"},
>         { Opt_rdma, "rdma"},
> +       { Opt_multichannel, "multichannel" },
> +       { Opt_nomultichannel, "nomultichannel" },
>
>         { Opt_backupuid, "backupuid=%s" },
>         { Opt_backupgid, "backupgid=%s" },
> @@ -218,6 +221,7 @@ static const match_table_t cifs_mount_option_tokens = {
>         { Opt_echo_interval, "echo_interval=%s" },
>         { Opt_max_credits, "max_credits=%s" },
>         { Opt_snapshot, "snapshot=%s" },
> +       { Opt_max_channels, "max_channels=%s" },
>         { Opt_compress, "compress=%s" },
>
>         { Opt_blank_user, "user=" },
> @@ -1664,6 +1668,10 @@ cifs_parse_mount_options(const char *mountdata, const char *devname,
>
>         vol->echo_interval = SMB_ECHO_INTERVAL_DEFAULT;
>
> +       /* default to no multichannel (single server connection) */
> +       vol->multichannel = false;
> +       vol->max_channels = 1;
> +
>         if (!mountdata)
>                 goto cifs_parse_mount_err;
>
> @@ -1957,6 +1965,12 @@ cifs_parse_mount_options(const char *mountdata, const char *devname,
>                 case Opt_rdma:
>                         vol->rdma = true;
>                         break;
> +               case Opt_multichannel:
> +                       vol->multichannel = true;
> +                       break;
> +               case Opt_nomultichannel:
> +                       vol->multichannel = false;
> +                       break;
>                 case Opt_compress:
>                         vol->compression = UNKNOWN_TYPE;
>                         cifs_dbg(VFS,
> @@ -2120,6 +2134,15 @@ cifs_parse_mount_options(const char *mountdata, const char *devname,
>                         }
>                         vol->max_credits = option;
>                         break;
> +               case Opt_max_channels:
> +                       if (get_option_ul(args, &option) || option < 1 ||
> +                               option > CIFS_MAX_CHANNELS) {
> +                               cifs_dbg(VFS, "%s: Invalid max_channels value, needs to be 1-%d\n",
> +                                        __func__, CIFS_MAX_CHANNELS);
> +                               goto cifs_parse_mount_err;
> +                       }
> +                       vol->max_channels = option;
> +                       break;
>
>                 /* String Arguments */
>
> @@ -2665,6 +2688,7 @@ cifs_put_tcp_session(struct TCP_Server_Info *server, int from_reconnect)
>  {
>         struct task_struct *task;
>
> +       cifs_dbg(VFS, "XXX server %px", server);
>         spin_lock(&cifs_tcp_ses_lock);
>         if (--server->srv_count > 0) {
>                 spin_unlock(&cifs_tcp_ses_lock);
> @@ -2705,7 +2729,7 @@ cifs_put_tcp_session(struct TCP_Server_Info *server, int from_reconnect)
>                 send_sig(SIGKILL, task, 1);
>  }
>
> -static struct TCP_Server_Info *
> +struct TCP_Server_Info *
>  cifs_get_tcp_session(struct smb_vol *volume_info)
>  {
>         struct TCP_Server_Info *tcp_ses = NULL;
> @@ -2764,7 +2788,10 @@ cifs_get_tcp_session(struct smb_vol *volume_info)
>                sizeof(tcp_ses->srcaddr));
>         memcpy(&tcp_ses->dstaddr, &volume_info->dstaddr,
>                 sizeof(tcp_ses->dstaddr));
> -       generate_random_uuid(tcp_ses->client_guid);
> +       if (volume_info->use_client_guid)
> +               memcpy(tcp_ses->client_guid, volume_info->client_guid, SMB2_CLIENT_GUID_SIZE);
> +       else
> +               generate_random_uuid(tcp_ses->client_guid);
>         /*
>          * at this point we are the only ones with the pointer
>          * to the struct since the kernel thread not created yet
> @@ -2853,6 +2880,13 @@ static int match_session(struct cifs_ses *ses, struct smb_vol *vol)
>             vol->sectype != ses->sectype)
>                 return 0;
>
> +       /*
> +        * If an existing session is limited to less channels than
> +        * requested, it should not be reused
> +        */
> +       if (ses->chan_max < vol->max_channels)
> +               return 0;
> +
>         switch (ses->sectype) {
>         case Kerberos:
>                 if (!uid_eq(vol->cred_uid, ses->cred_uid))
> @@ -3269,14 +3303,25 @@ cifs_get_smb_ses(struct TCP_Server_Info *server, struct smb_vol *volume_info)
>         ses->sectype = volume_info->sectype;
>         ses->sign = volume_info->sign;
>         mutex_lock(&ses->session_mutex);
> +
> +       /* add server as first channel */
> +       ses->chans[0].server = server;
> +       ses->chan_count = 1;
> +       ses->chan_max = volume_info->multichannel ? volume_info->max_channels:1;
> +
>         rc = cifs_negotiate_protocol(xid, ses);
>         if (!rc)
>                 rc = cifs_setup_session(xid, ses, volume_info->local_nls);
> +
> +       /* each channel uses a different signing key */
> +       memcpy(ses->chans[0].signkey, ses->smb3signingkey,
> +              sizeof(ses->smb3signingkey));
> +
>         mutex_unlock(&ses->session_mutex);
>         if (rc)
>                 goto get_ses_fail;
>
> -       /* success, put it on the list */
> +       /* success, put it on the list and add it as first channel */
>         spin_lock(&cifs_tcp_ses_lock);
>         list_add(&ses->smb_ses_list, &server->smb_ses_list);
>         spin_unlock(&cifs_tcp_ses_lock);
> @@ -4885,6 +4930,7 @@ int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb_vol *vol)
>         cifs_autodisable_serverino(cifs_sb);
>  out:
>         free_xid(xid);
> +       cifs_try_adding_channels(ses);
>         return mount_setup_tlink(cifs_sb, ses, tcon);
>
>  error:
> @@ -5130,7 +5176,7 @@ int
>  cifs_negotiate_protocol(const unsigned int xid, struct cifs_ses *ses)
>  {
>         int rc = 0;
> -       struct TCP_Server_Info *server = ses->server;
> +       struct TCP_Server_Info *server = cifs_ses_server(ses);
>
>         if (!server->ops->need_neg || !server->ops->negotiate)
>                 return -ENOSYS;
> @@ -5157,23 +5203,25 @@ cifs_setup_session(const unsigned int xid, struct cifs_ses *ses,
>                    struct nls_table *nls_info)
>  {
>         int rc = -ENOSYS;
> -       struct TCP_Server_Info *server = ses->server;
> -
> -       ses->capabilities = server->capabilities;
> -       if (linuxExtEnabled == 0)
> -               ses->capabilities &= (~server->vals->cap_unix);
> +       struct TCP_Server_Info *server = cifs_ses_server(ses);
> +
> +       if (!ses->binding) {
> +               ses->capabilities = server->capabilities;
> +               if (linuxExtEnabled == 0)
> +                       ses->capabilities &= (~server->vals->cap_unix);
> +
> +               if (ses->auth_key.response) {
> +                       cifs_dbg(FYI, "Free previous auth_key.response = %p\n",
> +                                ses->auth_key.response);
> +                       kfree(ses->auth_key.response);
> +                       ses->auth_key.response = NULL;
> +                       ses->auth_key.len = 0;
> +               }
> +       }
>
>         cifs_dbg(FYI, "Security Mode: 0x%x Capabilities: 0x%x TimeAdjust: %d\n",
>                  server->sec_mode, server->capabilities, server->timeAdj);
>
> -       if (ses->auth_key.response) {
> -               cifs_dbg(FYI, "Free previous auth_key.response = %p\n",
> -                        ses->auth_key.response);
> -               kfree(ses->auth_key.response);
> -               ses->auth_key.response = NULL;
> -               ses->auth_key.len = 0;
> -       }
> -
>         if (server->ops->sess_setup)
>                 rc = server->ops->sess_setup(xid, ses, nls_info);
>
> diff --git a/fs/cifs/sess.c b/fs/cifs/sess.c
> index 4c764ff7edd2..20c73a42755d 100644
> --- a/fs/cifs/sess.c
> +++ b/fs/cifs/sess.c
> @@ -31,6 +31,217 @@
>  #include <linux/utsname.h>
>  #include <linux/slab.h>
>  #include "cifs_spnego.h"
> +#include "smb2proto.h"
> +
> +bool
> +is_server_using_iface(struct TCP_Server_Info *server,
> +                     struct cifs_server_iface *iface)
> +{
> +       struct sockaddr_in *i4 = (struct sockaddr_in *)&iface->sockaddr;
> +       struct sockaddr_in6 *i6 = (struct sockaddr_in6 *)&iface->sockaddr;
> +       struct sockaddr_in *s4 = (struct sockaddr_in *)&server->dstaddr;
> +       struct sockaddr_in6 *s6 = (struct sockaddr_in6 *)&server->dstaddr;
> +
> +       if (server->dstaddr.ss_family != iface->sockaddr.ss_family)
> +               return false;
> +       if (server->dstaddr.ss_family == AF_INET) {
> +               if (s4->sin_addr.s_addr != i4->sin_addr.s_addr)
> +                       return false;
> +       } else if (server->dstaddr.ss_family == AF_INET6) {
> +               if (memcmp(&s6->sin6_addr, &i6->sin6_addr,
> +                          sizeof(i6->sin6_addr)) != 0)
> +                       return false;
> +       } else {
> +               /* unknown family.. */
> +               return false;
> +       }
> +       return true;
> +}
> +
> +bool is_ses_using_iface(struct cifs_ses *ses, struct cifs_server_iface *iface)
> +{
> +       int i;
> +       for (i = 0; i < ses->chan_count; i++) {
> +               if (is_server_using_iface(ses->chans[i].server, iface))
> +                       return true;
> +       }
> +       return false;
> +}
> +
> +/* returns number of channels added */
> +int cifs_try_adding_channels(struct cifs_ses *ses)
> +{
> +       int old_chan_count = ses->chan_count;
> +       int left = ses->chan_max - ses->chan_count;
> +       int i = 0;
> +       int rc = 0;
> +
> +       if (left <= 0) {
> +               cifs_dbg(FYI,
> +                        "ses already at max_channels (%zu), nothing to open\n",
> +                        ses->chan_max);
> +               return 0;
> +       }
> +
> +       if (ses->server->dialect != SMB311_PROT_ID) {
> +               cifs_dbg(VFS, "multichannel is not supported on this protocol version, use 3.1.1\n");
> +               return 0;
> +       }
> +
> +       /* ifaces are sorted by speed, try them in order */
> +       for (i = 0; left > 0 && i < ses->iface_count; i++) {
> +               struct cifs_server_iface *iface;
> +
> +               iface = &ses->iface_list[i];
> +               if (is_ses_using_iface(ses, iface) && !iface->rss_capable)
> +                       continue;
> +
> +               rc = cifs_ses_add_channel(ses, iface);
> +               if (rc) {
> +                       cifs_dbg(FYI, "failed to open extra channel\n");
> +                       continue;
> +               }
> +
> +               cifs_dbg(FYI, "sucessfully opened new channel\n");
> +               left--;
> +       }
> +
> +       /*
> +        * TODO: if we still have channels left to open try to connect
> +        * to same RSS-capable iface multiple times
> +        */
> +
> +       return ses->chan_count - old_chan_count;
> +}
> +
> +int
> +cifs_ses_add_channel(struct cifs_ses *ses, struct cifs_server_iface *iface)
> +{
> +       struct cifs_chan *chan;
> +       struct smb_vol vol = {0};
> +       const char unc_fmt[] = "\\%s\\foo";
> +       char unc[sizeof(unc_fmt)+SERVER_NAME_LEN_WITH_NULL] = {0};
> +       struct sockaddr_in *ipv4 = (struct sockaddr_in *)&iface->sockaddr;
> +       struct sockaddr_in6 *ipv6 = (struct sockaddr_in6 *)&iface->sockaddr;
> +       int rc;
> +       unsigned int xid = get_xid();
> +
> +       cifs_dbg(FYI, "adding channel to ses %p (speed:%zu bps rdma:%s ",
> +                ses, iface->speed, iface->rdma_capable ? "yes" : "no");
> +       if (iface->sockaddr.ss_family == AF_INET)
> +               cifs_dbg(FYI, "ip:%pI4)\n", &ipv4->sin_addr);
> +       else
> +               cifs_dbg(FYI, "ip:%pI6)\n", &ipv6->sin6_addr);
> +
> +       /*
> +        * Setup a smb_vol with mostly the same info as the existing
> +        * session and overwrite it with the requested iface data.
> +        *
> +        * We need to setup at least the fields used for negprot and
> +        * sesssetup.
> +        *
> +        * We only need the volume here, so we can reuse memory from
> +        * the session and server without caring about memory
> +        * management.
> +        */
> +
> +       /* Always make new connection for now (TODO?) */
> +       vol.nosharesock = true;
> +
> +       /* Auth */
> +       vol.domainauto = ses->domainAuto;
> +       vol.domainname = ses->domainName;
> +       vol.username = ses->user_name;
> +       vol.password = ses->password;
> +       vol.sectype = ses->sectype;
> +       vol.sign = ses->sign;
> +
> +       /* UNC and paths */
> +       /* XXX: Use ses->server->hostname? */
> +       sprintf(unc, unc_fmt, ses->serverName);
> +       vol.UNC = unc;
> +       vol.prepath = "";
> +
> +       /* Require SMB3.1.1 */
> +       vol.vals = &smb311_values;
> +       vol.ops = &smb311_operations;
> +
> +       vol.noblocksnd = ses->server->noblocksnd;
> +       vol.noautotune = ses->server->noautotune;
> +       vol.sockopt_tcp_nodelay = ses->server->tcp_nodelay;
> +       vol.echo_interval = ses->server->echo_interval / HZ;
> +
> +       /*
> +        * This will be used for encoding/decoding user/domain/pw
> +        * during sess setup auth.
> +        *
> +        * XXX: We use the default for simplicity but the proper way
> +        * would be to use the one that ses used, which is not
> +        * stored. This might break when dealing with non-ascii
> +        * strings.
> +        */
> +       vol.local_nls = load_nls_default();
> +
> +       /* Use RDMA if possible */
> +       vol.rdma = iface->rdma_capable;
> +       memcpy(&vol.dstaddr, &iface->sockaddr, sizeof(struct sockaddr_storage));
> +
> +       /* reuse master con client guid */
> +       memcpy(&vol.client_guid, ses->server->client_guid, SMB2_CLIENT_GUID_SIZE);
> +       vol.use_client_guid = true;
> +
> +       mutex_lock(&ses->session_mutex);
> +
> +       chan = &ses->chans[ses->chan_count];
> +       chan->server = cifs_get_tcp_session(&vol);
> +       if (IS_ERR(chan->server)) {
> +               rc = PTR_ERR(chan->server);
> +               chan->server = NULL;
> +               goto out;
> +       }
> +
> +       /*
> +        * We need to allocate the server crypto now as we will need
> +        * to sign packets before we generate the channel signing key
> +        * (we sign with the session key)
> +        */
> +       rc = smb311_crypto_shash_allocate(chan->server);
> +       if (rc) {
> +               cifs_dbg(VFS, "%s: crypto alloc failed\n", __func__);
> +               goto out;
> +       }
> +
> +       ses->binding = true;
> +       rc = cifs_negotiate_protocol(xid, ses);
> +       if (rc)
> +               goto out;
> +
> +       rc = cifs_setup_session(xid, ses, vol.local_nls);
> +       if (rc)
> +               goto out;
> +
> +       /* success, put it on the list
> +        * XXX: sharing ses between 2 tcp server is not possible, the
> +        * way "internal" linked lists works in linux makes element
> +        * only able to belong to one list
> +        *
> +        * the binding session is already established so the rest of
> +        * the code should be able to look it up, no need to add the
> +        * ses to the new server.
> +        */
> +
> +       ses->chan_count++;
> +
> +out:
> +       ses->binding = false;
> +       mutex_unlock(&ses->session_mutex);
> +
> +       if (rc && chan->server)
> +               cifs_put_tcp_session(chan->server, 0);
> +       unload_nls(vol.local_nls);
> +
> +       return rc;
> +}
>
>  static __u32 cifs_ssetup_hdr(struct cifs_ses *ses, SESSION_SETUP_ANDX *pSMB)
>  {
> @@ -342,6 +553,7 @@ int decode_ntlmssp_challenge(char *bcc_ptr, int blob_len,
>  void build_ntlmssp_negotiate_blob(unsigned char *pbuffer,
>                                          struct cifs_ses *ses)
>  {
> +       struct TCP_Server_Info *server = cifs_ses_server(ses);
>         NEGOTIATE_MESSAGE *sec_blob = (NEGOTIATE_MESSAGE *)pbuffer;
>         __u32 flags;
>
> @@ -354,9 +566,9 @@ void build_ntlmssp_negotiate_blob(unsigned char *pbuffer,
>                 NTLMSSP_NEGOTIATE_128 | NTLMSSP_NEGOTIATE_UNICODE |
>                 NTLMSSP_NEGOTIATE_NTLM | NTLMSSP_NEGOTIATE_EXTENDED_SEC |
>                 NTLMSSP_NEGOTIATE_SEAL;
> -       if (ses->server->sign)
> +       if (server->sign)
>                 flags |= NTLMSSP_NEGOTIATE_SIGN;
> -       if (!ses->server->session_estab || ses->ntlmssp->sesskey_per_smbsess)
> +       if (!server->session_estab || ses->ntlmssp->sesskey_per_smbsess)
>                 flags |= NTLMSSP_NEGOTIATE_KEY_XCH;
>
>         sec_blob->NegotiateFlags = cpu_to_le32(flags);
> diff --git a/fs/cifs/smb2misc.c b/fs/cifs/smb2misc.c
> index e311f58dc1c8..a95ed951c67f 100644
> --- a/fs/cifs/smb2misc.c
> +++ b/fs/cifs/smb2misc.c
> @@ -29,6 +29,7 @@
>  #include "cifs_unicode.h"
>  #include "smb2status.h"
>  #include "smb2glob.h"
> +#include "nterr.h"
>
>  static int
>  check_smb2_hdr(struct smb2_sync_hdr *shdr, __u64 mid)
> @@ -788,23 +789,37 @@ smb311_update_preauth_hash(struct cifs_ses *ses, struct kvec *iov, int nvec)
>         int i, rc;
>         struct sdesc *d;
>         struct smb2_sync_hdr *hdr;
> +       struct TCP_Server_Info *server = cifs_ses_server(ses);
>
> -       if (ses->server->tcpStatus == CifsGood) {
> -               /* skip non smb311 connections */
> -               if (ses->server->dialect != SMB311_PROT_ID)
> -                       return 0;
> +       hdr = (struct smb2_sync_hdr *)iov[0].iov_base;
> +       /* neg prot are always taken */
> +       if (hdr->Command == SMB2_NEGOTIATE)
> +               goto ok;
>
> -               /* skip last sess setup response */
> -               hdr = (struct smb2_sync_hdr *)iov[0].iov_base;
> -               if (hdr->Flags & SMB2_FLAGS_SIGNED)
> -                       return 0;
> -       }
> +       /*
> +        * If we process a command which wasn't a negprot it means the
> +        * neg prot was already done, so the server dialect was set
> +        * and we can test it. Preauth requires 3.1.1 for now.
> +        */
> +       if (server->dialect != SMB311_PROT_ID)
> +               return 0;
> +
> +       if (hdr->Command != SMB2_SESSION_SETUP)
> +               return 0;
> +
> +       /* skip last sess setup response */
> +       if ((hdr->Flags & SMB2_FLAGS_SERVER_TO_REDIR)
> +           && (hdr->Status == NT_STATUS_OK
> +               || (hdr->Status !=
> +                   cpu_to_le32(NT_STATUS_MORE_PROCESSING_REQUIRED))))
> +               return 0;
>
> -       rc = smb311_crypto_shash_allocate(ses->server);
> +ok:
> +       rc = smb311_crypto_shash_allocate(server);
>         if (rc)
>                 return rc;
>
> -       d = ses->server->secmech.sdescsha512;
> +       d = server->secmech.sdescsha512;
>         rc = crypto_shash_init(&d->shash);
>         if (rc) {
>                 cifs_dbg(VFS, "%s: could not init sha512 shash\n", __func__);
> diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
> index eaed18061314..0e66dc1aa1c9 100644
> --- a/fs/cifs/smb2ops.c
> +++ b/fs/cifs/smb2ops.c
> @@ -10,6 +10,7 @@
>  #include <linux/falloc.h>
>  #include <linux/scatterlist.h>
>  #include <linux/uuid.h>
> +#include <linux/sort.h>
>  #include <crypto/aead.h>
>  #include "cifsglob.h"
>  #include "smb2pdu.h"
> @@ -315,7 +316,7 @@ smb2_negotiate(const unsigned int xid, struct cifs_ses *ses)
>  {
>         int rc;
>
> -       ses->server->CurrentMid = 0;
> +       cifs_ses_server(ses)->CurrentMid = 0;
>         rc = SMB2_negotiate(xid, ses);
>         /* BB we probably don't need to retry with modern servers */
>         if (rc == -EAGAIN)
> @@ -558,6 +559,13 @@ parse_server_interfaces(struct network_interface_info_ioctl_rsp *buf,
>         return rc;
>  }
>
> +static int compare_iface(const void *ia, const void *ib)
> +{
> +       const struct cifs_server_iface *a = (struct cifs_server_iface *)ia;
> +       const struct cifs_server_iface *b = (struct cifs_server_iface *)ib;
> +
> +       return a->speed == b->speed ? 0 : (a->speed > b->speed ? -1 : 1);
> +}
>
>  static int
>  SMB3_request_interfaces(const unsigned int xid, struct cifs_tcon *tcon)
> @@ -587,6 +595,9 @@ SMB3_request_interfaces(const unsigned int xid, struct cifs_tcon *tcon)
>         if (rc)
>                 goto out;
>
> +       /* sort interfaces from fastest to slowest */
> +       sort(iface_list, iface_count, sizeof(*iface_list), compare_iface, NULL);
> +
>         spin_lock(&ses->iface_lock);
>         kfree(ses->iface_list);
>         ses->iface_list = iface_list;
> diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
> index 87066f1af12c..8bcb278fdb0a 100644
> --- a/fs/cifs/smb2pdu.c
> +++ b/fs/cifs/smb2pdu.c
> @@ -789,7 +789,7 @@ SMB2_negotiate(const unsigned int xid, struct cifs_ses *ses)
>         struct kvec rsp_iov;
>         int rc = 0;
>         int resp_buftype;
> -       struct TCP_Server_Info *server = ses->server;
> +       struct TCP_Server_Info *server = cifs_ses_server(ses);
>         int blob_offset, blob_length;
>         char *security_blob;
>         int flags = CIFS_NEG_OP;
> @@ -811,7 +811,7 @@ SMB2_negotiate(const unsigned int xid, struct cifs_ses *ses)
>         memset(server->preauth_sha_hash, 0, SMB2_PREAUTH_HASH_SIZE);
>         memset(ses->preauth_sha_hash, 0, SMB2_PREAUTH_HASH_SIZE);
>
> -       if (strcmp(ses->server->vals->version_string,
> +       if (strcmp(server->vals->version_string,
>                    SMB3ANY_VERSION_STRING) == 0) {
>                 req->Dialects[0] = cpu_to_le16(SMB30_PROT_ID);
>                 req->Dialects[1] = cpu_to_le16(SMB302_PROT_ID);
> @@ -827,7 +827,7 @@ SMB2_negotiate(const unsigned int xid, struct cifs_ses *ses)
>                 total_len += 8;
>         } else {
>                 /* otherwise send specific dialect */
> -               req->Dialects[0] = cpu_to_le16(ses->server->vals->protocol_id);
> +               req->Dialects[0] = cpu_to_le16(server->vals->protocol_id);
>                 req->DialectCount = cpu_to_le16(1);
>                 total_len += 2;
>         }
> @@ -1169,7 +1169,7 @@ SMB2_sess_alloc_buffer(struct SMB2_sess_data *sess_data)
>         int rc;
>         struct cifs_ses *ses = sess_data->ses;
>         struct smb2_sess_setup_req *req;
> -       struct TCP_Server_Info *server = ses->server;
> +       struct TCP_Server_Info *server = cifs_ses_server(ses);
>         unsigned int total_len;
>
>         rc = smb2_plain_req_init(SMB2_SESSION_SETUP, NULL, (void **) &req,
> @@ -1177,13 +1177,18 @@ SMB2_sess_alloc_buffer(struct SMB2_sess_data *sess_data)
>         if (rc)
>                 return rc;
>
> -       /* First session, not a reauthenticate */
> -       req->sync_hdr.SessionId = 0;
> -
> -       /* if reconnect, we need to send previous sess id, otherwise it is 0 */
> -       req->PreviousSessionId = sess_data->previous_session;
> -
> -       req->Flags = 0; /* MBZ */
> +       if (sess_data->ses->binding) {
> +               req->sync_hdr.SessionId = sess_data->ses->Suid;
> +               req->sync_hdr.Flags |= SMB2_FLAGS_SIGNED;
> +               req->PreviousSessionId = 0;
> +               req->Flags = SMB2_SESSION_REQ_FLAG_BINDING;
> +       } else {
> +               /* First session, not a reauthenticate */
> +               req->sync_hdr.SessionId = 0;
> +               /* if reconnect, we need to send previous sess id, otherwise it is 0 */
> +               req->PreviousSessionId = sess_data->previous_session;
> +               req->Flags = 0; /* MBZ */
> +       }
>
>         /* enough to enable echos and oplocks and one max size write */
>         req->sync_hdr.CreditRequest = cpu_to_le16(130);
> @@ -1256,28 +1261,33 @@ SMB2_sess_establish_session(struct SMB2_sess_data *sess_data)
>  {
>         int rc = 0;
>         struct cifs_ses *ses = sess_data->ses;
> +       struct TCP_Server_Info *server = cifs_ses_server(ses);
>
> -       mutex_lock(&ses->server->srv_mutex);
> -       if (ses->server->ops->generate_signingkey) {
> -               rc = ses->server->ops->generate_signingkey(ses);
> +       mutex_lock(&server->srv_mutex);
> +       if (server->ops->generate_signingkey) {
> +               rc = server->ops->generate_signingkey(ses);
>                 if (rc) {
>                         cifs_dbg(FYI,
>                                 "SMB3 session key generation failed\n");
> -                       mutex_unlock(&ses->server->srv_mutex);
> +                       mutex_unlock(&server->srv_mutex);
>                         return rc;
>                 }
>         }
> -       if (!ses->server->session_estab) {
> -               ses->server->sequence_number = 0x2;
> -               ses->server->session_estab = true;
> +       if (!server->session_estab) {
> +               server->sequence_number = 0x2;
> +               server->session_estab = true;
>         }
> -       mutex_unlock(&ses->server->srv_mutex);
> +       mutex_unlock(&server->srv_mutex);
>
>         cifs_dbg(FYI, "SMB2/3 session established successfully\n");
> -       spin_lock(&GlobalMid_Lock);
> -       ses->status = CifsGood;
> -       ses->need_reconnect = false;
> -       spin_unlock(&GlobalMid_Lock);
> +       /* keep exising ses state if binding */
> +       if (!ses->binding) {
> +               spin_lock(&GlobalMid_Lock);
> +               ses->status = CifsGood;
> +               ses->need_reconnect = false;
> +               spin_unlock(&GlobalMid_Lock);
> +       }
> +
>         return rc;
>  }
>
> @@ -1315,16 +1325,19 @@ SMB2_auth_kerberos(struct SMB2_sess_data *sess_data)
>                 goto out_put_spnego_key;
>         }
>
> -       ses->auth_key.response = kmemdup(msg->data, msg->sesskey_len,
> -                                        GFP_KERNEL);
> -       if (!ses->auth_key.response) {
> -               cifs_dbg(VFS,
> -                       "Kerberos can't allocate (%u bytes) memory",
> -                       msg->sesskey_len);
> -               rc = -ENOMEM;
> -               goto out_put_spnego_key;
> +       /* keep session key if binding */
> +       if (!ses->binding) {
> +               ses->auth_key.response = kmemdup(msg->data, msg->sesskey_len,
> +                                                GFP_KERNEL);
> +               if (!ses->auth_key.response) {
> +                       cifs_dbg(VFS,
> +                                "Kerberos can't allocate (%u bytes) memory",
> +                                msg->sesskey_len);
> +                       rc = -ENOMEM;
> +                       goto out_put_spnego_key;
> +               }
> +               ses->auth_key.len = msg->sesskey_len;
>         }
> -       ses->auth_key.len = msg->sesskey_len;
>
>         sess_data->iov[1].iov_base = msg->data + msg->sesskey_len;
>         sess_data->iov[1].iov_len = msg->secblob_len;
> @@ -1334,9 +1347,11 @@ SMB2_auth_kerberos(struct SMB2_sess_data *sess_data)
>                 goto out_put_spnego_key;
>
>         rsp = (struct smb2_sess_setup_rsp *)sess_data->iov[0].iov_base;
> -       ses->Suid = rsp->sync_hdr.SessionId;
> -
> -       ses->session_flags = le16_to_cpu(rsp->SessionFlags);
> +       /* keep session id and flags if binding */
> +       if (!ses->binding) {
> +               ses->Suid = rsp->sync_hdr.SessionId;
> +               ses->session_flags = le16_to_cpu(rsp->SessionFlags);
> +       }
>
>         rc = SMB2_sess_establish_session(sess_data);
>  out_put_spnego_key:
> @@ -1430,9 +1445,11 @@ SMB2_sess_auth_rawntlmssp_negotiate(struct SMB2_sess_data *sess_data)
>
>         cifs_dbg(FYI, "rawntlmssp session setup challenge phase\n");
>
> -
> -       ses->Suid = rsp->sync_hdr.SessionId;
> -       ses->session_flags = le16_to_cpu(rsp->SessionFlags);
> +       /* keep existing ses id and flags if binding */
> +       if (!ses->binding) {
> +               ses->Suid = rsp->sync_hdr.SessionId;
> +               ses->session_flags = le16_to_cpu(rsp->SessionFlags);
> +       }
>
>  out:
>         kfree(ntlmssp_blob);
> @@ -1489,8 +1506,11 @@ SMB2_sess_auth_rawntlmssp_authenticate(struct SMB2_sess_data *sess_data)
>
>         rsp = (struct smb2_sess_setup_rsp *)sess_data->iov[0].iov_base;
>
> -       ses->Suid = rsp->sync_hdr.SessionId;
> -       ses->session_flags = le16_to_cpu(rsp->SessionFlags);
> +       /* keep existing ses id and flags if binding */
> +       if (!ses->binding) {
> +               ses->Suid = rsp->sync_hdr.SessionId;
> +               ses->session_flags = le16_to_cpu(rsp->SessionFlags);
> +       }
>
>         rc = SMB2_sess_establish_session(sess_data);
>  out:
> @@ -1507,7 +1527,7 @@ SMB2_select_sec(struct cifs_ses *ses, struct SMB2_sess_data *sess_data)
>  {
>         int type;
>
> -       type = smb2_select_sectype(ses->server, ses->sectype);
> +       type = smb2_select_sectype(cifs_ses_server(ses), ses->sectype);
>         cifs_dbg(FYI, "sess setup type %d\n", type);
>         if (type == Unspecified) {
>                 cifs_dbg(VFS,
> @@ -1535,7 +1555,7 @@ SMB2_sess_setup(const unsigned int xid, struct cifs_ses *ses,
>                 const struct nls_table *nls_cp)
>  {
>         int rc = 0;
> -       struct TCP_Server_Info *server = ses->server;
> +       struct TCP_Server_Info *server = cifs_ses_server(ses);
>         struct SMB2_sess_data *sess_data;
>
>         cifs_dbg(FYI, "Session Setup\n");
> @@ -1561,7 +1581,7 @@ SMB2_sess_setup(const unsigned int xid, struct cifs_ses *ses,
>         /*
>          * Initialize the session hash with the server one.
>          */
> -       memcpy(ses->preauth_sha_hash, ses->server->preauth_sha_hash,
> +       memcpy(ses->preauth_sha_hash, server->preauth_sha_hash,
>                SMB2_PREAUTH_HASH_SIZE);
>
>         while (sess_data->func)
> diff --git a/fs/cifs/smb2proto.h b/fs/cifs/smb2proto.h
> index 67a91b11fd59..804b6dc5546b 100644
> --- a/fs/cifs/smb2proto.h
> +++ b/fs/cifs/smb2proto.h
> @@ -46,7 +46,8 @@ extern int smb2_verify_signature(struct smb_rqst *, struct TCP_Server_Info *);
>  extern int smb2_check_receive(struct mid_q_entry *mid,
>                               struct TCP_Server_Info *server, bool log_error);
>  extern struct mid_q_entry *smb2_setup_request(struct cifs_ses *ses,
> -                             struct smb_rqst *rqst);
> +                                             struct TCP_Server_Info *,
> +                                             struct smb_rqst *rqst);
>  extern struct mid_q_entry *smb2_setup_async_request(
>                         struct TCP_Server_Info *server, struct smb_rqst *rqst);
>  extern struct cifs_ses *smb2_find_smb_ses(struct TCP_Server_Info *server,
> diff --git a/fs/cifs/smb2transport.c b/fs/cifs/smb2transport.c
> index 148d7942c796..539cf2fc1f3b 100644
> --- a/fs/cifs/smb2transport.c
> +++ b/fs/cifs/smb2transport.c
> @@ -48,7 +48,7 @@ smb2_crypto_shash_allocate(struct TCP_Server_Info *server)
>                                &server->secmech.sdeschmacsha256);
>  }
>
> -static int
> +int
>  smb3_crypto_shash_allocate(struct TCP_Server_Info *server)
>  {
>         struct cifs_secmech *p = &server->secmech;
> @@ -98,6 +98,47 @@ smb311_crypto_shash_allocate(struct TCP_Server_Info *server)
>         return rc;
>  }
>
> +u8 *smb2_find_chan_signkey(struct cifs_ses *ses, struct TCP_Server_Info *server)
> +{
> +       int i;
> +       struct cifs_chan *chan;
> +       int count;
> +       spin_lock(&cifs_tcp_ses_lock);
> +       count = ses->chan_count;
> +       if (ses->binding)
> +               count++;
> +       for (i = 0; i < count; i++) {
> +               chan = ses->chans + i;
> +               if (chan->server == server) {
> +                       spin_unlock(&cifs_tcp_ses_lock);
> +                       return chan->signkey;
> +               }
> +       }
> +       spin_unlock(&cifs_tcp_ses_lock);
> +       return NULL;
> +}
> +
> +struct cifs_ses *
> +smb2_find_global_smb_ses(__u64 ses_id)
> +{
> +       struct TCP_Server_Info *server;
> +       struct cifs_ses *ses;
> +       cifs_dbg(VFS, "XXX: searching for sesid %llu", ses_id);
> +       spin_lock(&cifs_tcp_ses_lock);
> +       list_for_each_entry(server, &cifs_tcp_ses_list, tcp_ses_list) {
> +               cifs_dbg(VFS, "XXX: server %px ", server);
> +               list_for_each_entry(ses, &server->smb_ses_list, smb_ses_list) {
> +                       cifs_dbg(VFS, "XXX: ses %px ", ses);
> +                       if (ses->Suid == ses_id) {
> +                               spin_unlock(&cifs_tcp_ses_lock);
> +                               return ses;
> +                       }
> +               }
> +       }
> +       spin_unlock(&cifs_tcp_ses_lock);
> +       return NULL;
> +}
> +
>  static struct cifs_ses *
>  smb2_find_smb_ses_unlocked(struct TCP_Server_Info *server, __u64 ses_id)
>  {
> @@ -328,21 +369,34 @@ generate_smb3signingkey(struct cifs_ses *ses,
>  {
>         int rc;
>
> -       rc = generate_key(ses, ptriplet->signing.label,
> -                         ptriplet->signing.context, ses->smb3signingkey,
> -                         SMB3_SIGN_KEY_SIZE);
> -       if (rc)
> -               return rc;
> -
> -       rc = generate_key(ses, ptriplet->encryption.label,
> -                         ptriplet->encryption.context, ses->smb3encryptionkey,
> -                         SMB3_SIGN_KEY_SIZE);
> -       if (rc)
> -               return rc;
> -
> -       rc = generate_key(ses, ptriplet->decryption.label,
> -                         ptriplet->decryption.context,
> -                         ses->smb3decryptionkey, SMB3_SIGN_KEY_SIZE);
> +       if (ses->binding) {
> +               struct TCP_Server_Info *server;
> +               cifs_dbg(VFS, "XXX: BINDING! gen signkey");
> +               server = cifs_ses_server(ses);
> +               rc = generate_key(ses, ptriplet->signing.label,
> +                                 ptriplet->signing.context,
> +                                 smb2_find_chan_signkey(ses, server),
> +                                 SMB3_SIGN_KEY_SIZE);
> +               if (rc)
> +                       return rc;
> +       } else {
> +               rc = generate_key(ses, ptriplet->signing.label,
> +                                 ptriplet->signing.context,
> +                                 ses->smb3signingkey,
> +                                 SMB3_SIGN_KEY_SIZE);
> +               if (rc)
> +                       return rc;
> +               rc = generate_key(ses, ptriplet->encryption.label,
> +                                 ptriplet->encryption.context,
> +                                 ses->smb3encryptionkey,
> +                                 SMB3_SIGN_KEY_SIZE);
> +               rc = generate_key(ses, ptriplet->decryption.label,
> +                                 ptriplet->decryption.context,
> +                                 ses->smb3decryptionkey,
> +                                 SMB3_SIGN_KEY_SIZE);
> +               if (rc)
> +                       return rc;
> +       }
>
>         if (rc)
>                 return rc;
> @@ -434,18 +488,35 @@ smb3_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
>         struct cifs_ses *ses;
>         struct shash_desc *shash = &server->secmech.sdesccmacaes->shash;
>         struct smb_rqst drqst;
> +       u8 *key;
>
> -       ses = smb2_find_smb_ses(server, shdr->SessionId);
> +       ses = smb2_find_global_smb_ses(shdr->SessionId);
>         if (!ses) {
>                 cifs_server_dbg(VFS, "%s: Could not find session\n", __func__);
>                 return 0;
>         }
>
> +       /*
> +        * If we are binding an existing session use the session key,
> +        * otherwise use the channel key
> +        */
> +       if (ses->binding) {
> +               key = ses->smb3signingkey;
> +               cifs_dbg(VFS, "XXX: using bind ses key %px", key);
> +       } else {
> +               key = smb2_find_chan_signkey(ses, server);
> +               cifs_dbg(VFS, "XXX: using chan ses key %px", key);
> +               if (!key) {
> +                       cifs_dbg(VFS, "XXX: could not find channel key");
> +                       return 0;
> +               }
> +        }
> +
>         memset(smb3_signature, 0x0, SMB2_CMACAES_SIZE);
>         memset(shdr->Signature, 0x0, SMB2_SIGNATURE_SIZE);
>
>         rc = crypto_shash_setkey(server->secmech.cmacaes,
> -                                ses->smb3signingkey, SMB2_CMACAES_SIZE);
> +                                key, SMB2_CMACAES_SIZE);
>         if (rc) {
>                 cifs_server_dbg(VFS, "%s: Could not set key for cmac aes\n", __func__);
>                 return rc;
> @@ -494,18 +565,35 @@ static int
>  smb2_sign_rqst(struct smb_rqst *rqst, struct TCP_Server_Info *server)
>  {
>         int rc = 0;
> -       struct smb2_sync_hdr *shdr =
> -                       (struct smb2_sync_hdr *)rqst->rq_iov[0].iov_base;
> +       struct smb2_sync_hdr *shdr;
> +       struct smb2_sess_setup_req *ssr;
> +       bool is_binding;
> +       bool is_signed;
>
> -       if (!(shdr->Flags & SMB2_FLAGS_SIGNED) ||
> -           server->tcpStatus == CifsNeedNegotiate)
> -               return rc;
> +       shdr = (struct smb2_sync_hdr *)rqst->rq_iov[0].iov_base;
> +       ssr = (struct smb2_sess_setup_req *)shdr;
>
> -       if (!server->session_estab) {
> +       is_binding = shdr->Command == SMB2_SESSION_SETUP &&
> +               (ssr->Flags & SMB2_SESSION_REQ_FLAG_BINDING);
> +       is_signed = shdr->Flags & SMB2_FLAGS_SIGNED;
> +
> +       printk(KERN_WARNING "XXX: sign_rqst\n");
> +
> +       if (!is_signed) {
> +               printk(KERN_WARNING "XXX: no signed flag\n");
> +               return 0;
> +       }
> +       if (server->tcpStatus == CifsNeedNegotiate) {
> +               printk(KERN_WARNING "XXX: need nego\n");
> +               return 0;
> +       }
> +       if (!is_binding && !server->session_estab) {
>                 strncpy(shdr->Signature, "BSRSPYL", 8);
> -               return rc;
> +               printk(KERN_WARNING "XXX: !session_estab\n");
> +               return 0;
>         }
>
> +       printk(KERN_WARNING "XXX: actually signing!\n");
>         rc = server->ops->calc_signature(rqst, server);
>
>         return rc;
> @@ -610,18 +698,18 @@ smb2_mid_entry_alloc(const struct smb2_sync_hdr *shdr,
>  }
>
>  static int
> -smb2_get_mid_entry(struct cifs_ses *ses, struct smb2_sync_hdr *shdr,
> +smb2_get_mid_entry(struct cifs_ses *ses, struct TCP_Server_Info *server, struct smb2_sync_hdr *shdr,
>                    struct mid_q_entry **mid)
>  {
> -       if (ses->server->tcpStatus == CifsExiting)
> +       if (server->tcpStatus == CifsExiting)
>                 return -ENOENT;
>
> -       if (ses->server->tcpStatus == CifsNeedReconnect) {
> +       if (server->tcpStatus == CifsNeedReconnect) {
>                 cifs_dbg(FYI, "tcp session dead - return to caller to retry\n");
>                 return -EAGAIN;
>         }
>
> -       if (ses->server->tcpStatus == CifsNeedNegotiate &&
> +       if (server->tcpStatus == CifsNeedNegotiate &&
>            shdr->Command != SMB2_NEGOTIATE)
>                 return -EAGAIN;
>
> @@ -638,11 +726,11 @@ smb2_get_mid_entry(struct cifs_ses *ses, struct smb2_sync_hdr *shdr,
>                 /* else ok - we are shutting down the session */
>         }
>
> -       *mid = smb2_mid_entry_alloc(shdr, ses->server);
> +       *mid = smb2_mid_entry_alloc(shdr, server);
>         if (*mid == NULL)
>                 return -ENOMEM;
>         spin_lock(&GlobalMid_Lock);
> -       list_add_tail(&(*mid)->qhead, &ses->server->pending_mid_q);
> +       list_add_tail(&(*mid)->qhead, &server->pending_mid_q);
>         spin_unlock(&GlobalMid_Lock);
>
>         return 0;
> @@ -675,24 +763,24 @@ smb2_check_receive(struct mid_q_entry *mid, struct TCP_Server_Info *server,
>  }
>
>  struct mid_q_entry *
> -smb2_setup_request(struct cifs_ses *ses, struct smb_rqst *rqst)
> +smb2_setup_request(struct cifs_ses *ses, struct TCP_Server_Info *server, struct smb_rqst *rqst)
>  {
>         int rc;
>         struct smb2_sync_hdr *shdr =
>                         (struct smb2_sync_hdr *)rqst->rq_iov[0].iov_base;
>         struct mid_q_entry *mid;
>
> -       smb2_seq_num_into_buf(ses->server, shdr);
> +       smb2_seq_num_into_buf(server, shdr);
>
> -       rc = smb2_get_mid_entry(ses, shdr, &mid);
> +       rc = smb2_get_mid_entry(ses, server, shdr, &mid);
>         if (rc) {
> -               revert_current_mid_from_hdr(ses->server, shdr);
> +               revert_current_mid_from_hdr(server, shdr);
>                 return ERR_PTR(rc);
>         }
>
> -       rc = smb2_sign_rqst(rqst, ses->server);
> +       rc = smb2_sign_rqst(rqst, server);
>         if (rc) {
> -               revert_current_mid_from_hdr(ses->server, shdr);
> +               revert_current_mid_from_hdr(server, shdr);
>                 cifs_delete_mid(mid);
>                 return ERR_PTR(rc);
>         }
> diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
> index 308ad0f495e1..a4c2d62ee437 100644
> --- a/fs/cifs/transport.c
> +++ b/fs/cifs/transport.c
> @@ -923,7 +923,7 @@ cifs_check_receive(struct mid_q_entry *mid, struct TCP_Server_Info *server,
>  }
>
>  struct mid_q_entry *
> -cifs_setup_request(struct cifs_ses *ses, struct smb_rqst *rqst)
> +cifs_setup_request(struct cifs_ses *ses, struct TCP_Server_Info *ignored, struct smb_rqst *rqst)
>  {
>         int rc;
>         struct smb_hdr *hdr = (struct smb_hdr *)rqst->rq_iov[0].iov_base;
> @@ -995,7 +995,15 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
>                 return -EIO;
>         }
>
> -       server = ses->server;
> +       if (!ses->binding) {
> +               uint index = ((unsigned)get_random_int()) % ses->chan_count;
> +               cifs_dbg(VFS, "XXX: send/recv: using random channel %d", index);
> +               server = ses->chans[index].server;
> +       } else {
> +               cifs_dbg(VFS, "XXX: send/recv: binding, using last serv");
> +               server = cifs_ses_server(ses);
> +       }
> +
>         if (server->tcpStatus == CifsExiting)
>                 return -ENOENT;
>
> @@ -1040,7 +1048,7 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
>         }
>
>         for (i = 0; i < num_rqst; i++) {
> -               midQ[i] = server->ops->setup_request(ses, &rqst[i]);
> +               midQ[i] = server->ops->setup_request(ses, server, &rqst[i]);
>                 if (IS_ERR(midQ[i])) {
>                         revert_current_mid(server, i);
>                         for (j = 0; j < i; j++)
> --
> 2.16.4
>


-- 
Thanks,

Steve

^ permalink raw reply	[flat|nested] 4+ messages in thread

* [WIP] multichannel
@ 2019-06-11 14:47 aaptel
  0 siblings, 0 replies; 4+ messages in thread
From: aaptel @ 2019-06-11 14:47 UTC (permalink / raw)
  To: linux-cifs

Hi,

Since I was asked about my multichannel progress at SambaXP I thought I
would send the current state of the code as a WIP for maybe early
feedback. I've discussed it already a bit with Pavel last year when I
was working on it.

I've sort of resurected my multichannel branch and put it on github.
It is based on cifs as of last year so in the middle of compounding and
before the DFS failover (which refactored a lot of reconnection code and
mount code).

Also I now understand cifs reconnection code enough to know that the
multichannel recon code is most likely wrong and needs to be rewritten
:)

I'm juggling large backports for SUSE, debugging customer bugs, the
POSIX extensions reparse point stuff, being a GSoC mentor this summer
and it seems I'm never finishing anything which is pretty
frustrating... anyway (/rant)

Code is *old* but available on my github on the multichannel-v2 branch
as a big single "wip" commit...

https://github.com/aaptel/linux.git multichan-v2

https://github.com/aaptel/linux/commit/bcc0ac27a03e100a5f444ab012cc27711919cf74

Here is a *simplified* overview of the changes:

Datastructure changes
=====================

I've added an array of cifs_chan inside cifs_ses.
I could have added an array of TCP_Server_Info but since a channel uses
a different signing key and signing keys are stored in cifs_ses I needed
the extra struct.

+struct cifs_chan {
+       struct TCP_Server_Info *server;
+       __u8 signkey[SMB3_SIGN_KEY_SIZE];
+};

...

@@ -881,12 +890,15 @@ struct cifs_ses {
        bool sign;              /* is signing required? */
        bool need_reconnect:1; /* connection reset, uid now invalid */
        bool domainAuto:1;
+       bool binding:1; /* are we binding the session? */
        __u16 session_flags;
        __u8 smb3signingkey[SMB3_SIGN_KEY_SIZE];
        __u8 smb3encryptionkey[SMB3_SIGN_KEY_SIZE];
        __u8 smb3decryptionkey[SMB3_SIGN_KEY_SIZE];
        __u8 preauth_sha_hash[SMB2_PREAUTH_HASH_SIZE];
 
@@ -900,8 +912,22 @@ struct cifs_ses {
        struct cifs_server_iface *iface_list;
        size_t iface_count;
        unsigned long iface_last_update; /* jiffies */
+
+#define CIFS_MAX_CHANNELS 16
+       struct cifs_chan chans[CIFS_MAX_CHANNELS];
+       size_t chan_count;
+       size_t chan_max;
 };

The "main" channel is still ses->server (copied to ses->chans[0] for
convinience too)

Sending-to-the-wire code changes
================================

When sending something on the wire, instead of sending it to ses->server
we send it to a random one instead for now:

@@ -809,7 +810,16 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
 
+       if (!ses->binding) {
+               uint index = ((unsigned)get_random_int()) % ses->chan_count;
+               cifs_dbg(VFS, "XXX: send/recv: using random channel %d", index);
+               server = ses->chans[index].server;
+       } else {
+               cifs_dbg(VFS, "XXX: send/recv: binding, using last serv");
+               server = cifs_ses_server(ses);
+       }

Couple of func in that code path take a ses as input but really only use
server properties (we are doing the low-level work of sending after all)
so I had to refactor things a bit to pass just the server, or pass ses
AND server (and remove ses->server usage).

Session establishment code changes
==================================

Currently a lot of the code to initialize a connection & session uses
the cifs_ses as input. But depending on if we are opening a new session
or a new channel we need to use different server pointers. So I've added
a "binding" flag in cifs_ses and this helper function that returns the
current server a session should use (only in the sess establishment code
path):

+static inline
+struct TCP_Server_Info *cifs_ses_server(struct cifs_ses *ses)
+{
+       if (ses->binding)
+               return ses->chans[ses->chan_count].server;
                 //                ^^^^^return the last channel (always the new one)
+       else
+               return ses->server;
+}
+

Which needs to be used in all the code related to establishing a
session. A lot of changes are basically turning this:

void foo(struct cifs_ses *ses, ...)
{
    ses->server->...;
    func(ses->server, ...);
    ...
}

into this:

void foo(struct cifs_ses *ses, ...)
{
    TCP_Server_Info *server = cifs_ses_server(ses);

    server->...;
    func(server, ...);
    ...
}

Mount code changes
==================

- "max_channels=N"
  Sets the max number of channel (set this to 2 or more to get extra
  connections)
  
- "[no]multichannel"
  enables multichannel, without this max_channel will be ignored.

The reason for those 2 steps is so that user can enable multichannel
without having to know the details of how it works. Right now we decide
manually via max_channels but in the future it could be dynamic.

After doing cifs_mount() sucessfully we call cifs_try_adding_channels()
which will open as many channels as it can.

+/* returns number of channels added */
+int cifs_try_adding_channels(struct cifs_ses *ses)
+{
+       int old_chan_count = ses->chan_count;
+       int left = ses->chan_max - ses->chan_count;
+       int i = 0;
+       int rc = 0;
+
+       if (left <= 0) {
+               cifs_dbg(FYI,
+                        "ses already at max_channels (%zu), nothing to open\n",
+                        ses->chan_max);
+               return 0;
+       }
+
+       if (ses->server->dialect != SMB311_PROT_ID) {
+               cifs_dbg(VFS, "multichannel is not supported on this protocol version, use 3.1.1\n");
+               return 0;
+       }
+
+       /* ifaces are sorted by speed, try them in order */
+       for (i = 0; left > 0 && i < ses->iface_count; i++) {
+               struct cifs_server_iface *iface;
+
+               iface = &ses->iface_list[i];
+               if (is_ses_using_iface(ses, iface) && !iface->rss_capable)
+                       continue;
+
+               rc = cifs_ses_add_channel(ses, iface);
+               if (rc) {
+                       cifs_dbg(FYI, "failed to open extra channel\n");
+                       continue;
+               }
+
+               cifs_dbg(FYI, "sucessfully opened new channel\n");
+               left--;
+       }
+
+       /*
+        * TODO: if we still have channels left to open try to connect
+        * to same RSS-capable iface multiple times
+        */
+
+       return ses->chan_count - old_chan_count;
+}


Which in turns calls cifs_ses_add_chanel() to add a channel to an
existing session by connecting to iface:

+cifs_ses_add_channel(struct cifs_ses *ses, struct cifs_server_iface *iface)
+{
+       struct cifs_chan *chan;
+       struct smb_vol vol = {0};
+       const char unc_fmt[] = "\\%s\\foo";
+       char unc[sizeof(unc_fmt)+SERVER_NAME_LEN_WITH_NULL] = {0};
+       struct sockaddr_in *ipv4 = (struct sockaddr_in *)&iface->sockaddr;
+       struct sockaddr_in6 *ipv6 = (struct sockaddr_in6 *)&iface->sockaddr;
+       int rc;
+       unsigned int xid = get_xid();
+
+       cifs_dbg(FYI, "adding channel to ses %p (speed:%zu bps rdma:%s ",
+                ses, iface->speed, iface->rdma_capable ? "yes" : "no");
+       if (iface->sockaddr.ss_family == AF_INET)
+               cifs_dbg(FYI, "ip:%pI4)\n", &ipv4->sin_addr);
+       else
+               cifs_dbg(FYI, "ip:%pI6)\n", &ipv6->sin6_addr);
+
+       /*
+        * Setup a smb_vol with mostly the same info as the existing
+        * session and overwrite it with the requested iface data.
+        *
+        * We need to setup at least the fields used for negprot and
+        * sesssetup.
+        *
+        * We only need the volume here, so we can reuse memory from
+        * the session and server without caring about memory
+        * management.
+        */
+
+       /* Always make new connection for now (TODO?) */
+       vol.nosharesock = true;
+
+       /* Auth */
+       vol.domainauto = ses->domainAuto;
+       vol.domainname = ses->domainName;
+       vol.username = ses->user_name;
+       vol.password = ses->password;
+       vol.sectype = ses->sectype;
+       vol.sign = ses->sign;
+
+       /* UNC and paths */
+       /* XXX: Use ses->server->hostname? */
+       sprintf(unc, unc_fmt, ses->serverName);
+       vol.UNC = unc;
+       vol.prepath = "";
+
+       /* Require SMB3.1.1 */
+       vol.vals = &smb311_values;
+       vol.ops = &smb311_operations;
+
+       vol.noblocksnd = ses->server->noblocksnd;
+       vol.noautotune = ses->server->noautotune;
+       vol.sockopt_tcp_nodelay = ses->server->tcp_nodelay;
+       vol.echo_interval = ses->server->echo_interval / HZ;
+
+       /*
+        * This will be used for encoding/decoding user/domain/pw
+        * during sess setup auth.
+        *
+        * XXX: We use the default for simplicity but the proper way
+        * would be to use the one that ses used, which is not
+        * stored. This might break when dealing with non-ascii
+        * strings.
+        */
+       vol.local_nls = load_nls_default();
+
+       /* Use RDMA if possible */
+       vol.rdma = iface->rdma_capable;
+       memcpy(&vol.dstaddr, &iface->sockaddr, sizeof(struct sockaddr_storage));
+
+       mutex_lock(&ses->session_mutex);
+
+       chan = &ses->chans[ses->chan_count];
+       chan->server = cifs_get_tcp_session(&vol);
+       if (IS_ERR(chan->server)) {
+               rc = PTR_ERR(chan->server);
+               chan->server = NULL;
+               goto out;
+       }
+
+       /*
+        * We need to allocate the server crypto now as we will need
+        * to sign packets before we generate the channel signing key
+        * (we sign with the session key)
+        */
+       rc = smb311_crypto_shash_allocate(chan->server);


Locking
=======

I'm not sure things are race-free. The ses->binding flag could be an
issue.

For signing, we need to have access to the session a channel belongs
to... but we actually cannot walk "up" from the server to the
session. So I decided to walk "down" from the global
cifs_tcp_ses_list. But that requires taking the global spinlock for each
packet we sign. Probably not good for parallelism. See
smb2_find_global_smb_ses() usages.


Testing
=======

I have only tested this on a simple Win 2016 VM. Just add network
interfaces to the VM, Windows automatically lists them back when doing a
FSCTL_QUERY_INTERFACE.

Then mount from linux with -o multichannel,max_channels=2

Look at DebugData, network traces or dmesg for runtime info.

I have not made many any benchmark, reconnection tests, DFS tests,
or compounding tests so this really is WIP but I'm very interested in
people trying it anyway :)

Cheers,
-- 
Aurélien Aptel / SUSE Labs Samba Team
GPG: 1839 CB5F 9F5B FB9B AA97  8C99 03C8 A49B 521B D5D3
SUSE Linux GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany
GF: Felix Imendörffer, Mary Higgins, Sri Rasiah HRB 21284 (AG Nürnberg)


^ permalink raw reply	[flat|nested] 4+ messages in thread

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-- links below jump to the message on this page --
2019-09-17 22:14 [WIP] multichannel Aurelien Aptel
2019-09-17 23:51 ` [WIP v3] multichannel Aurelien Aptel
2019-09-18  2:44   ` Steve French
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2019-06-11 14:47 [WIP] multichannel aaptel

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