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. mitrandir@fb.com provided some extra fixes for the dispatch code and for hg-ssh in places that I overlooked.

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from __future__ import absolute_import, print_function

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import os

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from hgext import (

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    color,

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)

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from mercurial import (

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    dispatch,

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    ui as uimod,

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)

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# ensure errors aren't buffered

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testui = color.colorui()

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testui.pushbuffer()

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testui.write(('buffered\n'))

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testui.warn(('warning\n'))

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testui.write_err('error\n')

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print(repr(testui.popbuffer()))

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# test dispatch.dispatch with the same ui object

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hgrc = open(os.environ["HGRCPATH"], 'w')

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hgrc.write('[extensions]\n')

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hgrc.write('color=\n')

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hgrc.close()

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ui_ = uimod.ui.load()

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ui_.setconfig('ui', 'formatted', 'True')

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# we're not interested in the output, so write that to devnull

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ui_.fout = open(os.devnull, 'w')

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# call some arbitrary command just so we go through

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# color's wrapped _runcommand twice.

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def runcmd():

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    dispatch.dispatch(dispatch.request(['version', '-q'], ui_))

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runcmd()

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print("colored? " + str(issubclass(ui_.__class__, color.colorui)))

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runcmd()

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print("colored? " + str(issubclass(ui_.__class__, color.colorui)))