[Privoxy-devel] PATCH for pcre2 support

Thu Mar 16 10:56:09 CET 2023

Gagan Sidhu <broly at mac.com> wrote on 2023-03-13 at 11:28:42:

> therefore it is not my changes per-se that are the problem.
> it is a combination of privoxy’s string preprocessing/postprocessing
> and pcre2 that is the problem.
> 
> i will also add the ’server’ is up. when you go to
> http://127.0.0.1:8118, you get the exact same output for pcre2 and pcre1.

Are you saying you are using the patch:
SHA256 (substandard_pcre2.patch) = 142f99e4b685fee8c6592ea47a89cc4ea29622744458e70d3ae1f370abd9df27
and get actual content when requesting http://127.0.0.1:8118/ and http://p.p:8118/?

> some people were kind enough to share some things that may break in pcre2 (that worked in pcre1):
> 
> https://stackoverflow.com/a/73767663 <https://stackoverflow.com/a/73767663>
> 
> any assistance on fixing this issue would be great.

Very interesting.

I noticed another problem with the patch.

Destination rewriting seems to reproducible result in a stack overflow:

fk at t520 ~/git/privoxy $gdb-privoxy
[...]
[New LWP 101318 of process 33334]
2023-03-16 10:47:16.223 801012700 Connect: Accepted connection from 127.0.0.1 on socket 6
2023-03-16 10:47:16.223 801012000 Connect: Waiting for the next client connection. Currently active threads: 1
2023-03-16 10:47:16.224 801012700 Header: scan: CONNECT twitter.com:443 HTTP/1.1
2023-03-16 10:47:16.225 801012700 Tagging: Tagger 'listen-address' added tag 'LISTEN-ADDRESS: 127.0.1.1:8118'. No action bits update necessary.
2023-03-16 10:47:16.225 801012700 Tagging: Tagger 'http-method' added tag 'CONNECT'. Action bits updated accordingly.
2023-03-16 10:47:16.225 801012700 Tagging: Tagger 'client-ip-address' added tag 'IP-ADDRESS: 127.0.0.1'. No action bits update necessary.
2023-03-16 10:47:16.225 801012700 Header: scan: User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:102.0) Gecko/20100101 Firefox/102.0
2023-03-16 10:47:16.225 801012700 Tagging: Tagger 'user-agent' added tag 'User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:102.0) Gecko/20100101 Firefox/102.0'. No action bits update necessary.
2023-03-16 10:47:16.225 801012700 Header: scan: Proxy-Connection: keep-alive
2023-03-16 10:47:16.225 801012700 Header: scan: Connection: keep-alive
2023-03-16 10:47:16.226 801012700 Header: scan: Host: twitter.com:443
2023-03-16 10:47:16.226 801012700 Header: Modified: User-Agent: Mozilla/5.0 (X11; NetBSD i386; rv:102.0) Gecko/20100101 Firefox/102.0
2023-03-16 10:47:16.226 801012700 Header: crumble crunched: Proxy-Connection: keep-alive!
2023-03-16 10:47:16.226 801012700 Header: Keeping the client header 'Connection: keep-alive' around. The server connection will be kept alive if possible.
2023-03-16 10:47:16.267 801012700 Connect: Performing the TLS/SSL handshake with client. Hash of host: 7905d1c4e12c54933a44d19fcd5f9356
2023-03-16 10:47:16.291 801012700 Connect: Client successfully connected over TLSv1.3 (TLS_AES_128_GCM_SHA256).
2023-03-16 10:47:16.291 801012700 Header: Waiting for encrypted client headers
2023-03-16 10:47:16.291 801012700 Header: Encrypted headers received completely
2023-03-16 10:47:16.291 801012700 Header: Destination extracted from "Host" header. New request URL: /TCNOco/status/1634620446002774018
2023-03-16 10:47:16.292 801012700 Header: scan: GET /TCNOco/status/1634620446002774018 HTTP/1.1
2023-03-16 10:47:16.292 801012700 Tagging: Tagger 'listen-address' added tag 'LISTEN-ADDRESS: 127.0.1.1:8118'. No action bits update necessary.
2023-03-16 10:47:16.292 801012700 Tagging: Tagger 'http-method' added tag 'GET'. No action bits update necessary.
2023-03-16 10:47:16.292 801012700 Tagging: Tagger 'client-ip-address' added tag 'IP-ADDRESS: 127.0.0.1'. No action bits update necessary.
2023-03-16 10:47:16.292 801012700 Header: scan: Host: twitter.com
2023-03-16 10:47:16.292 801012700 Header: scan: User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:102.0) Gecko/20100101 Firefox/102.0
2023-03-16 10:47:16.293 801012700 Tagging: Tagger 'user-agent' added tag 'User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:102.0) Gecko/20100101 Firefox/102.0'. No action bits update necessary.
2023-03-16 10:47:16.293 801012700 Header: scan: Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,*/*;q=0.8
2023-03-16 10:47:16.293 801012700 Header: scan: Accept-Language: en-CA
2023-03-16 10:47:16.293 801012700 Header: scan: Accept-Encoding: gzip, deflate, br
2023-03-16 10:47:16.293 801012700 Header: scan: DNT: 1
2023-03-16 10:47:16.293 801012700 Header: scan: Connection: keep-alive
2023-03-16 10:47:16.293 801012700 Header: scan: Upgrade-Insecure-Requests: 1
2023-03-16 10:47:16.293 801012700 Header: scan: Sec-Fetch-Dest: document
2023-03-16 10:47:16.294 801012700 Header: scan: Sec-Fetch-Mode: navigate
2023-03-16 10:47:16.294 801012700 Header: scan: Sec-Fetch-Site: none
2023-03-16 10:47:16.294 801012700 Header: scan: Sec-Fetch-User: ?1
2023-03-16 10:47:16.294 801012700 Header: Modified: User-Agent: Mozilla/5.0 (X11; NetBSD i386; rv:102.0) Gecko/20100101 Firefox/102.0
2023-03-16 10:47:16.294 801012700 Header: Keeping the client header 'Connection: keep-alive' around. The server connection will be kept alive if possible.
2023-03-16 10:47:16.294 801012700 Header: Accept-Language header crunched and replaced with: Accept-Language: en-nz
2023-03-16 10:47:16.294 801012700 Header: Encrypted request headers processed
2023-03-16 10:47:16.294 801012700 Request: https://twitter.com/TCNOco/status/1634620446002774018
2023-03-16 10:47:16.294 801012700 Redirect: pcrs command "s@^https?://twitter.com/([^?]*)@http://vfaomgh4jxphpbdfizkm5gbtjahmei234giqj4facbwhrfjtcldauqad.onion/$1@" changed "https://twitter.com/TCNOco/status/1634620446002774018" to "http://vfaomgh4jxphpbdfizkm5gbtjahmei234giqj4facbwhrfjtcldauqad.onion/TCNOco/status/1634620446002774018" (1 hit).

Thread 2 received signal SIGABRT, Aborted.
Sent by kill() from pid 33334 and user 1001.
[Switching to LWP 101318 of process 33334]
kill () at kill.S:4
4	kill.S: No such file or directory.
(gdb) where
#0  kill () at kill.S:4
#1  0x000000080089b4e0 in __fail (msg=0x8007a57a4 "stack overflow detected; terminated") at /usr/src/lib/libc/secure/stack_protector.c:130
#2  0x000000080089b450 in __stack_chk_fail () at /usr/src/lib/libc/secure/stack_protector.c:137
#3  0x000000000024abfd in rewrite_url (old_url=0x801c28100 "https://twitter.com/TCNOco/status/1634620446002774018", 
    pcrs_command=0x801c10000 "s@^https?://twitter.com/([^?]*)@http://vfaomgh4jxphpbdfizkm5gbtjahmei234giqj4facbwhrfjtcldauqad.onion/$1@") at filters.c:1038
#4  0x000000000024ad07 in redirect_url (csp=0x8010f1008) at filters.c:1257
#5  0x00000000002583b5 in crunch_response_triggered (csp=0x8010f1008, crunchers=0x218920 <crunchers_all>) at jcc.c:953
#6  0x00000000002569d6 in chat (csp=0x8010f1008) at jcc.c:4482
#7  0x0000000000255736 in serve (csp=0x8010f1008) at jcc.c:5056
#8  0x0000000800745a7a in thread_start (curthread=0x801012700) at /usr/src/lib/libthr/thread/thr_create.c:292
#9  0x0000000000000000 in ?? ()
Backtrace stopped: Cannot access memory at address 0x7fffdfffe000

The rewrite is enabled with an action like:

{+redirect{s@^https?://twitter.com/([^?]*)@http://vfaomgh4jxphpbdfizkm5gbtjahmei234giqj4facbwhrfjtcldauqad.onion/$1@}}
twitter.com

Fabian
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