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Implemented possible solution for path traversal #28

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@schenkd schenkd self-requested a review July 1, 2020 17:13
@schenkd schenkd self-assigned this Jul 1, 2020
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Hey Chris, thanks for your PR. It looks good and you're solving a problem for the v0.3 release, thanks for that!

config_file = os.path.join(nginx_path, name)

if not os.path.commonprefix(os.path.realpath(config_file), nginx_path):
return flask.make_response({'success': False}), 200
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I would choose a different status code. For example a 400 (Bad Request) or 403 (Forbidden).

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@erikgeiser erikgeiser Jul 1, 2020

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Also note that os.path.commonprefix(("/a/b", "/c/d")) returns "/" which is truthy, so the condition is not met. And commonprefix takes an iterable and not variadic arguments so I think this errors out. Maybe use something like os.path.realpath(config_file).startswith(os.path.realpath(nginx_path) + os.sep) (though not as this ugly oneliner maybe).

@@ -57,6 +62,9 @@ def get_domains():
sites_available = []
sites_enabled = []

if not os.path.exists(config_path):
errorMessage = 'The config folder "{}" does not exists.'.format(config_path)
return flask.render_template('domains.html', errorMessage=errorMessage, sites_available=(), sites_enabled=()), 200
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Classic case of Java developer. Lower CamelCase is uncommon in Python. error_message would be nice! :)

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@schenkd schenkd Jul 1, 2020

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I would also like to have the string formatting with f-string syntax. Then it will be consistent in the code.

error_message = f'The config folder "{config_path}" doesn't exists.'

@@ -1,6 +1,11 @@
<div class="column">

<div class="ui cards" id="domain_cards">
{% if errorMessage %}
<div>
{{errorMessage}}
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@schenkd schenkd Jul 1, 2020

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It is functional, but you could enhance it with a message from the semantic framework. Here is a link to the component: Error Messages

@schenkd schenkd changed the base branch from master to dev-0.3 July 1, 2020 17:26
@schenkd schenkd assigned chris18191 and unassigned schenkd Jul 1, 2020
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It seems like you addressed the path traversal issue only in a single endpoint. Looking through endpoints.py, it seems that most API endpoints work rather similar an possibly share the same issue.

@schenkd schenkd added this to In progress in Version 0.3 Jul 1, 2020
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I added a new function to generate valid paths or return None if the path is not valid, e.g. it is no subdirectory of the given folder.
Errors can now also easily be visualized by calling rendeError, which makes use Semantics error message.

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schenkd commented Jul 2, 2020

I added a new function to generate valid paths or return None if the path is not valid, e.g. it is no subdirectory of the given folder.
Errors can now also easily be visualized by calling rendeError, which makes use Semantics error message.

@chris18191 First of all, thank you very much for your efforts. I see you're using lower camel-case everywhere. I did not want to mention every method in the review. Could you adapt it to the Python convention? Unfortunately, I will not be able to do an extensive review before the weekend.

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Possible arbitrary file access though Path Traversal vulnerability in some situations
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