tests/svnxml.py

dispatch: protect against malicious 'hg serve --stdio' invocations (sec)

Some shared-ssh installations assume that 'hg serve --stdio' is a safe
command to run for minimally trusted users. Unfortunately, the messy
implementation of argument parsing here meant that trying to access a
repo named '--debugger' would give the user a pdb prompt, thereby
sidestepping any hoped-for sandboxing. Serving repositories over HTTP(S)
is unaffected.

We're not currently hardening any subcommands other than 'serve'. If
your service exposes other commands to users with arbitrary repository
names, it is imperative that you defend against repository names of
'--debugger' and anything starting with '--config'.

The read-only mode of hg-ssh stopped working because it provided its hook
configuration to "hg serve --stdio" via --config parameter. This is banned for
security reasons now. This patch switches it to directly call ui.setconfig().
If your custom hosting infrastructure relies on passing --config to
"hg serve --stdio", you'll need to find a different way to get that configuration
into Mercurial, either by using ui.setconfig() as hg-ssh does in this patch,
or by placing an hgrc file someplace where Mercurial will read it.

[e-mail] provided some extra fixes for the dispatch code and
for hg-ssh in places that I overlooked.

# Read the output of a "svn log --xml" command on stdin, parse it and
# print a subset of attributes common to all svn versions tested by
# hg.
from __future__ import absolute_import
import sys
import xml.dom.minidom

def xmltext(e):
    return ''.join(c.data for c
                   in e.childNodes
                   if c.nodeType == c.TEXT_NODE)

def parseentry(entry):
    e = {}
    e['revision'] = entry.getAttribute('revision')
    e['author'] = xmltext(entry.getElementsByTagName('author')[0])
    e['msg'] = xmltext(entry.getElementsByTagName('msg')[0])
    e['paths'] = []
    paths = entry.getElementsByTagName('paths')
    if paths:
        paths = paths[0]
        for p in paths.getElementsByTagName('path'):
            action = p.getAttribute('action')
            path = xmltext(p)
            frompath = p.getAttribute('copyfrom-path')
            fromrev = p.getAttribute('copyfrom-rev')
            e['paths'].append((path, action, frompath, fromrev))
    return e

def parselog(data):
    entries = []
    doc = xml.dom.minidom.parseString(data)
    for e in doc.getElementsByTagName('logentry'):
        entries.append(parseentry(e))
    return entries

def printentries(entries):
    fp = sys.stdout
    for e in entries:
        for k in ('revision', 'author', 'msg'):
            fp.write(('%s: %s\n' % (k, e[k])).encode('utf-8'))
        for path, action, fpath, frev in sorted(e['paths']):
            frominfo = ''
            if frev:
                frominfo = ' (from %s@%s)' % (fpath, frev)
            p = ' %s %s%s\n' % (action, path, frominfo)
            fp.write(p.encode('utf-8'))

if __name__ == '__main__':
    data = sys.stdin.read()
    entries = parselog(data)
    printentries(entries)