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https://issues.apache.org/jira/browse/TS-3283?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Phil Sorber updated TS-3283:
----------------------------
Backport to Version: 4.2.3
> Certain SSL handshake error during client-hello hangs the client and leaves
> network connection open
> ---------------------------------------------------------------------------------------------------
>
> Key: TS-3283
> URL: https://issues.apache.org/jira/browse/TS-3283
> Project: Traffic Server
> Issue Type: Bug
> Components: SSL
> Reporter: Joe Chung
> Assignee: Susan Hinrichs
> Fix For: 5.3.0
>
>
> h3. Problem Description
> Send an SSLv2 Client Hello with an old cipher suite request against Traffic
> Server 4.2.2, and the connection will freeze on the client side and
> eventually time out after 120 seconds.
> The Traffic Server detects the SSL error, but instead of closing the
> connection, goes on to accept new connections.
> h3. Reproduction
> === Client: Macbook Pro running OSX Mavericks 10.9.5 ===
> {code:none}
> $ openssl version -a
> OpenSSL 0.9.8za 5 Jun 2014
> built on: Aug 10 2014
> platform: darwin64-x86_64-llvm
> options: bn(64,64) md2(int) rc4(ptr,char) des(idx,cisc,16,int) blowfish(idx)
> compiler: -arch x86_64 -fmessage-length=0 -pipe -Wno-trigraphs
> -fpascal-strings -fasm-blocks -O3 -D_REENTRANT -DDSO_DLFCN -DHAVE_DLFCN_H
> -DL_ENDIAN -DMD32_REG_T=int -DOPENSSL_NO_IDEA -DOPENSSL_PIC -DOPENSSL_THREADS
> -DZLIB -mmacosx-version-min=10.6
> OPENSSLDIR: "/System/Library/OpenSSL"
> {code}
> h4. The following command triggers the bad behavior on the 4.2.2 server.
> {code:none}
> $ openssl s_client -connect 192.168.20.130:443 -ssl2 -debug
> CONNECTED(00000003)
> write to 0x7fb9f2508610 [0x7fb9f300f201] (45 bytes => 45 (0x2D))
> 0000 - 80 2b 01 00 02 00 12 00-00 00 10 07 00 c0 03 00 .+..............
> 0010 - 80 01 00 80 06 00 40 04-00 80 02 00 80 f4 71 1a ......@.......q.
> 0020 - ad 23 06 59 4d f8 d2 c5-b2 57 a9 66 4c .#.YM....W.fL
> ^C
> {code}
> At this point, the client is hung, and I have to hit ctrl-c to interrupt it
> or wait 120 seconds for tcp timeout.
> h3. Server: Lubuntu 13.10 on VMware
> {code:none}
> $ openssl version -a
> OpenSSL 1.0.1e 11 Feb 2013
> built on: Fri Jun 20 18:52:25 UTC 2014
> platform: debian-i386
> options: bn(64,32) rc4(8x,mmx) des(ptr,risc1,16,long) blowfish(idx)
> compiler: cc -fPIC -DOPENSSL_PIC -DZLIB -DOPENSSL_THREADS -D_REENTRANT
> -DDSO_DLFCN -DHAVE_DLFCN_H -DL_ENDIAN -DTERMIO -g -O2 -fstack-protector
> --param=ssp-buffer-size=4 -Wformat -Werror=format-security
> -D_FORTIFY_SOURCE=2 -Wl,-Bsymbolic-functions -Wl,-z,relro -Wa,--noexecstack
> -Wall -DOPENSSL_NO_TLS1_2_CLIENT -DOPENSSL_MAX_TLS1_2_CIPHER_LENGTH=50
> -DOPENSSL_BN_ASM_PART_WORDS -DOPENSSL_IA32_SSE2 -DOPENSSL_BN_ASM_MONT
> -DOPENSSL_BN_ASM_GF2m -DSHA1_ASM -DSHA256_ASM -DSHA512_ASM -DMD5_ASM
> -DRMD160_ASM -DAES_ASM -DVPAES_ASM -DWHIRLPOOL_ASM -DGHASH_ASM
> OPENSSLDIR: "/usr/lib/ssl"
> {code}
> {code:none}
> $ diff /usr/local/etc/trafficserver/records.config.422
> /usr/local/etc/trafficserver/records.config
> 113c113
> < CONFIG proxy.config.http.server_ports STRING 8080
> ---
> > CONFIG proxy.config.http.server_ports STRING 8080 443:ssl
> 594,595c594,595
> < CONFIG proxy.config.diags.debug.enabled INT 0
> < CONFIG proxy.config.diags.debug.tags STRING http.*|dns.*
> ---
> > CONFIG proxy.config.diags.debug.enabled INT 1
> > CONFIG proxy.config.diags.debug.tags STRING ssl.*
> {code}
> {code:none}
> $ /usr/local/bin/traffic_server --version
> [TrafficServer] using root directory '/usr/local'
> Apache Traffic Server - traffic_server - 4.2.2 - (build # 0723 on Jan 7 2015
> at 23:04:32)
> $ sudo /usr/local/bin/traffic_server
> [sudo] password for user:
> [TrafficServer] using root directory '/usr/local'
> [Jan 8 00:53:42.618] Server {0xb702e700} DEBUG: (ssl) setting SNI callbacks
> with for ctx 0xa4a7928
> [Jan 8 00:53:42.618] Server {0xb702e700} DEBUG: (ssl) indexed '*' with
> SSL_CTX 0xa4a7928
> [Jan 8 00:53:42.619] Server {0xb702e700} DEBUG: (ssl) importing SNI names
> from /usr/local/etc/trafficserver
> [Jan 8 00:54:02.256] Server {0xb6265b40} DEBUG: (ssl)
> [SSLNextProtocolAccept:mainEvent] event 202 netvc 0xb280fa90
> [Jan 8 00:54:02.256] Server {0xb6265b40} DEBUG: (ssl) ssl_callback_info ssl:
> 0xb280fcb8 where: 16 ret: 1
> [Jan 8 00:54:02.256] Server {0xb6265b40} DEBUG: (ssl) ssl_callback_info ssl:
> 0xb280fcb8 where: 8193 ret: 1
> [Jan 8 00:54:02.256] Server {0xb6265b40} DEBUG: (ssl) ssl_callback_info ssl:
> 0xb280fcb8 where: 8194 ret: -1
> [Jan 8 00:54:02.256] Server {0xb6265b40} DEBUG: (ssl)
> SSL::3055967040:error:140760FC:SSL routines:SSL23_GET_CLIENT_HELLO:unknown
> protocol:s23_srvr.c:628
> [Jan 8 00:54:02.256] Server {0xb6265b40} DEBUG: <SSLNetVConnection.cc:526
> (sslServerHandShakeEvent)> (ssl) SSL handshake error: SSL_ERROR_SSL (1),
> errno=0
> {code}
> At this point, the server has not closed the tcp connection, and has instead
> gone back to the accept loop, waiting for new connections.
> After 120 seconds (TCP timeout) the connection is eventually closed. During
> this time, the server process holds onto a file descriptor needlessly for 120
> seconds. I connected to the server from multiple clients and counted the
> server's number of open fds after each connection ({{sudo ls -1 /proc/$pid/fd
> | wc -l}}).
> This behavior makes the server vulnerable to a denial-of-service attack.
> h3. Possible Fix
> In gdb, I compared the behavior of 5.1.2 vs 4.2.2 in the face of an
> {{SSL_ERROR_SSL}} during the Client Hello handshake. I noticed that in 5.1.2,
> there is a {{netvc->do_io(VIO::CLOSE)}} in
> {{SSLNextProtocolTrampoline::ioCompletionEvent()}} that closes the TCP
> connection.
> When I apply the following diff to the 4.2.2 code base (essentially making
> this function look more like the 5.1.2 version), it fixes the problem; i.e.
> the server immediately closes the TCP connection after the error is detected.
> {code:none}
> $ git diff
> diff --git a/iocore/net/SSLNextProtocolAccept.cc
> b/iocore/net/SSLNextProtocolAccept.cc
> index bfc2f0b..a5612c6 100644
> --- a/iocore/net/SSLNextProtocolAccept.cc
> +++ b/iocore/net/SSLNextProtocolAccept.cc
> @@ -78,19 +78,22 @@ struct SSLNextProtocolTrampoline : public Continuation
> Continuation * plugin;
> SSLNetVConnection * netvc;
> + vio = static_cast<VIO *>(edata);
> + netvc = dynamic_cast<SSLNetVConnection *>(vio->vc_server);
> + ink_assert(netvc != NULL);
> +
> switch (event) {
> case VC_EVENT_INACTIVITY_TIMEOUT:
> - case VC_EVENT_READ_COMPLETE:
> case VC_EVENT_ERROR:
> - vio = static_cast<VIO *>(edata);
> + netvc->do_io(VIO::CLOSE);
> + delete this;
> + return EVENT_CONT;
> + case VC_EVENT_READ_COMPLETE:
> break;
> default:
> return EVENT_ERROR;
> }
> - netvc = dynamic_cast<SSLNetVConnection *>(vio->vc_server);
> - ink_assert(netvc != NULL);
> -
> plugin = netvc->endpoint();
> if (plugin) {
> send_plugin_event(plugin, NET_EVENT_ACCEPT, netvc);
> {code}
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