https://bz.apache.org/bugzilla/show_bug.cgi?id=57931
Bug ID: 57931
Summary: NIO connector incorrectly closes connection when
client certificate verification fails
Product: Tomcat 7
Version: 7.0.61
Hardware: PC
Status: NEW
Severity: normal
Priority: P2
Component: Connectors
Assignee: dev@tomcat.apache.org
Reporter: loths...@yahoo.com
Created attachment 32738
--> https://bz.apache.org/bugzilla/attachment.cgi?id=32738&action=edit
Test program to reproduce the issue
If tomcat is set to use TLS and clientAuth="want" or clientAuth="true", it
appears the NIO connector closes the connection in response to an untrusted
client certificate. This behavior differs from the BIO connector, and violates
RFC 5246, which states that a fatal alert must be provided if "some aspect of
the cert chain was unacceptable". By closing the connection, this causes
OpenSSL to provide an obscure error "Unexpected EOF", which indicates the TLS
protocol was violated.
I have attached a Python test program which demonstrates this behavior. Simply
run this program against a tomcat server, configured with the given server.xml
Connector shown below. Removal of the protocol attribute will use the BIO
connector, and inclusion of the protocol attribute will demonstrate the NIO
connector.
Steps to reproduce:
1) Setup a tomcat server with the connector configuration shown below
2) Install Python as well as pyOpenSSL
3) (If necessary) Modify the test.py program to communicate with the
appropriate server and port.
4) Run the test.py program.
(Alternatively, if Python is not available, you should be able to use
Desired behavior:
Instead of closing the connection, the NIO connector should provide a fatal
error response to an invalid certificate, like the BIO connector.
I would strongly prefer if the response would match the response provided by
Java through the BIO connector: "alert certificate unknown". This would allow
our program to use either connector without any changes.
Impact:
Due to this bug, when using the NIO connector, our program cannot differentiate
between an unexpected network problem and a certificate issue during the
handshake. Because of this, the program is not able to flag and react to the
possibility the certificate is invalid--it assumes an unexpected network error
occurred.
RFC 5246, 7.4.6. Client Certificate:
If the client does not send any certificates, the
server MAY at its discretion either continue the handshake without
client authentication, or respond with a fatal handshake_failure
alert. Also, if some aspect of the certificate chain was
unacceptable (e.g., it was not signed by a known, trusted CA), the
server MAY at its discretion either continue the handshake
(considering the client unauthenticated) or send a fatal alert.
NIO Connector (Incorrect behavior):
python test.py
Connecting...
Performing SSL handshake...
Traceback (most recent call last):
File "test.py", line 18, in <module>
conn.do_handshake()
OpenSSL.SSL.SysCallError: (-1, 'Unexpected EOF')
BIO connector (Correct behavior):
python test.py
Connecting...
Performing SSL handshake...
Traceback (most recent call last):
File "test.py", line 18, in <module>
conn.do_handshake()
File "build/bdist.linux-x86_64/egg/OpenSSL/SSL.py", line 1442, in
do_handshake
File "build/bdist.linux-x86_64/egg/OpenSSL/SSL.py", line 1187, in
_raise_ssl_error
File "build/bdist.linux-x86_64/egg/OpenSSL/_util.py", line 48, in
exception_from_error_queue
OpenSSL.SSL.Error: [('SSL routines', 'SSL3_READ_BYTES', 'sslv3 alert
certificate unknown')]
Connector Configuration:
<Connector port="10443" maxHttpHeaderSize="4096"
maxThreads="75" minSpareThreads="25"
maxKeepAliveRequests="-1"
keepAliveTimeout="180000"
enableLookups="false" disableUploadTimeout="true"
acceptCount="10" scheme="https" secure="true" SSLEnabled="true"
clientAuth="want" sslProtocol="TLS"
sslEnabledProtocols="TLSv1.2,TLSv1"
connectionTimeout="10000"
protocol="org.apache.coyote.http11.Http11NioProtocol"
keystoreFile="example.keystore"
keystorePass="example" algorithm="SunX509"
truststoreFile="example.keystore"
truststorePass="example"
truststoreType="JKS"
keyAlias="tomcat"
compression="on"
compressionMinSize="2048"
ciphers="TLS_DHE_RSA_WITH_AES_128_CBC_SHA"/>
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