CIFS: add CONFIG_CIFS_DEBUG_KEYS to dump encryption keys

Add new config option that dumps AES keys to the console when they are
generated. This is obviously for debugging purposes only, and should not
be enabled otherwise.

Signed-off-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <smfrench@gmail.com>
diff --git a/fs/cifs/Kconfig b/fs/cifs/Kconfig
index 034f00f..afeefe7 100644
--- a/fs/cifs/Kconfig
+++ b/fs/cifs/Kconfig
@@ -146,6 +146,15 @@
 	   option can be turned off unless you are debugging
 	   cifs problems.  If unsure, say N.
 
+config CIFS_DEBUG_DUMP_KEYS
+	bool "Dump encryption keys for offline decryption (Unsafe)"
+	depends on CIFS_DEBUG && CIFS_SMB2
+	help
+	   Enabling this will dump the encryption and decryption keys
+	   used to communicate on an encrypted share connection on the
+	   console. This allows Wireshark to decrypt and dissect
+	   encrypted network captures. Enable this carefully.
+
 config CIFS_DFS_UPCALL
 	  bool "DFS feature support"
 	  depends on CIFS && KEYS