[PATCH][SMB3 client] add dynamic trace point for session setup password expired failures

[Steve French <smfrench@xxxxxxxxx>]

There are cases where services need to remount (or change their
credentials files) when keys have expired, but it can be helpful
to have a dynamic trace point to make it easier to notify the
service to refresh the storage account key.

Here is sample output, one from mount with bad password, one
from a reconnect where the password has been changed or expired
and reconnect fails (requiring remount with new storage account key)

       TASK-PID     CPU#  |||||  TIMESTAMP  FUNCTION
          | |         |   |||||     |         |

  mount.cifs-11362  [000] .....  6000.241620: smb3_key_expired:
    rc=-13 user=testpassu conn_id=0x2 server=localhost addr=127.0.0.1:445
  kworker/4:0-8458  [004] .....  6044.892283: smb3_key_expired:
    rc=-13 user=testpassu conn_id=0x3 server=localhost addr=127.0.0.1:445

See attached patch

--

Thanks,

Steve

From d942133cc0a8fae6bddab3a194b00686b85a1d44 Mon Sep 17 00:00:00 2001
From: Steve French <stfrench@xxxxxxxxxxxxx>
Date: Fri, 26 Jul 2024 01:06:20 -0500
Subject: [PATCH] smb3: add dynamic trace point for session setup key expired
 failures

There are cases where services need to remount (or change their
credentials files) when keys have expired, but it can be helpful
to have a dynamic trace point to make it easier to notify the
service to refresh the storage account key.

Here is sample output, one from mount with bad password, one
from a reconnect where the password has been changed or expired
and reconnect fails (requiring remount with new storage account key)

       TASK-PID     CPU#  |||||  TIMESTAMP  FUNCTION
          | |         |   |||||     |         |

  mount.cifs-11362  [000] .....  6000.241620: smb3_key_expired:
    rc=-13 user=testpassu conn_id=0x2 server=localhost addr=127.0.0.1:445
  kworker/4:0-8458  [004] .....  6044.892283: smb3_key_expired:
    rc=-13 user=testpassu conn_id=0x3 server=localhost addr=127.0.0.1:445

Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
---
 fs/smb/client/smb2pdu.c |  8 +++++++-
 fs/smb/client/trace.h   | 40 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/fs/smb/client/smb2pdu.c b/fs/smb/client/smb2pdu.c
index 9fc5b11c0b6c..3dd5a7a02288 100644
--- a/fs/smb/client/smb2pdu.c
+++ b/fs/smb/client/smb2pdu.c
@@ -1562,8 +1562,14 @@ SMB2_sess_sendreceive(struct SMB2_sess_data *sess_data)
 	cifs_small_buf_release(sess_data->iov[0].iov_base);
 	if (rc == 0)
 		sess_data->ses->expired_pwd = false;
-	else if ((rc == -EACCES) || (rc == -EKEYEXPIRED) || (rc == -EKEYREVOKED))
+	else if ((rc == -EACCES) || (rc == -EKEYEXPIRED) || (rc == -EKEYREVOKED)) {
+		if (sess_data->ses->expired_pwd == false)
+			trace_smb3_key_expired(sess_data->server->hostname,
+					       sess_data->ses->user_name,
+					       sess_data->server->conn_id,
+					       &sess_data->server->dstaddr, rc);
 		sess_data->ses->expired_pwd = true;
+	}
 
 	memcpy(&sess_data->iov[0], &rsp_iov, sizeof(struct kvec));
 
diff --git a/fs/smb/client/trace.h b/fs/smb/client/trace.h
index bc4f8b3ad6ff..25e29c662672 100644
--- a/fs/smb/client/trace.h
+++ b/fs/smb/client/trace.h
@@ -1281,6 +1281,46 @@ DEFINE_EVENT(smb3_connect_err_class, smb3_##name,  \
 
 DEFINE_SMB3_CONNECT_ERR_EVENT(connect_err);
 
+DECLARE_EVENT_CLASS(smb3_sess_setup_err_class,
+	TP_PROTO(char *hostname, char *username, __u64 conn_id,
+		const struct __kernel_sockaddr_storage *dst_addr, int rc),
+	TP_ARGS(hostname, username, conn_id, dst_addr, rc),
+	TP_STRUCT__entry(
+		__string(hostname, hostname)
+		__string(username, username)
+		__field(__u64, conn_id)
+		__array(__u8, dst_addr, sizeof(struct sockaddr_storage))
+		__field(int, rc)
+	),
+	TP_fast_assign(
+		struct sockaddr_storage *pss = NULL;
+
+		__entry->conn_id = conn_id;
+		__entry->rc = rc;
+		pss = (struct sockaddr_storage *)__entry->dst_addr;
+		*pss = *dst_addr;
+		__assign_str(hostname);
+		__assign_str(username);
+	),
+	TP_printk("rc=%d user=%s conn_id=0x%llx server=%s addr=%pISpsfc",
+		__entry->rc,
+		__get_str(username),
+		__entry->conn_id,
+		__get_str(hostname),
+		__entry->dst_addr)
+)
+
+#define DEFINE_SMB3_SES_SETUP_ERR_EVENT(name)        \
+DEFINE_EVENT(smb3_sess_setup_err_class, smb3_##name,  \
+	TP_PROTO(char *hostname,		\
+		char *username,			\
+		__u64 conn_id,			\
+		const struct __kernel_sockaddr_storage *addr,	\
+		int rc),			\
+	TP_ARGS(hostname, username, conn_id, addr, rc))
+
+DEFINE_SMB3_SES_SETUP_ERR_EVENT(key_expired);
+
 DECLARE_EVENT_CLASS(smb3_reconnect_class,
 	TP_PROTO(__u64	currmid,
 		__u64 conn_id,
-- 
2.43.0