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The `load` and `load_all` methods will issue a warning when they are
called without the 'Loader=' parameter. The warning will point to a URL
that is always up to date with the latest information on the usage of
`load`.
There are several ways to stop the warning:
* Use `full_load(input)` - sugar for `yaml.load(input, FullLoader)`
* FullLoader is the new safe but complete loader class
* Use `safe_load(input)` - sugar for `yaml.load(input, SafeLoader)`
* Make sure your input YAML consists of the 'safe' subset
* Use `unsafe_load(input)` - sugar for `yaml.load(input, UnsafeLoader)`
* Make sure your input YAML consists of the 'safe' subset
* Use `yaml.load(input, Loader=yaml.<loader>)`
* Or shorter `yaml.load(input, yaml.<loader>)`
* Where '<loader>' can be:
* FullLoader - safe, complete Python YAML loading
* SafeLoader - safe, partial Python YAML loading
* UnsafeLoader - more explicit name for the old, unsafe 'Loader' class
* yaml.warnings({'YAMLLoadWarning': False})
* Use this when you use third party modules that use `yaml.load(input)`
* Only do this if input is trusted
The above `load()` expressions all have `load_all()` counterparts.
You can get the original unsafe behavior with:
* `yaml.unsafe_load(input)`
* `yaml.load(input, Loader=yaml.UnsafeLoader)`
In a future release, `yaml.load(input)` will raise an exception.
The new loader called FullLoader is almost entirely complete as
Loader/UnsafeLoader but it does it avoids all known code execution
paths. It is the preferred YAML loader, and the current default for
`yaml.load(input)` when you get the warning.
Here are some of the exploits that can be triggered with UnsafeLoader
but not with FullLoader:
```
python -c 'import os, yaml; yaml.full_load("!!python/object/new:os.system [echo EXPLOIT!]")'`
python -c 'import yaml; print yaml.full_load("!!python/object/new:abs [-5]")'
python -c 'import yaml; yaml.full_load("!!python/object/new:eval [exit(5)]")' ; echo $?
python -c 'import yaml; yaml.full_load("!!python/object/new:exit [5]")' ; echo $?
67 lines
2 KiB
Python
67 lines
2 KiB
Python
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import yaml, test_emitter
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def test_loader_error(error_filename, verbose=False):
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try:
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list(yaml.load_all(open(error_filename, 'rb'), yaml.FullLoader))
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except yaml.YAMLError, exc:
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if verbose:
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print "%s:" % exc.__class__.__name__, exc
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else:
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raise AssertionError("expected an exception")
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test_loader_error.unittest = ['.loader-error']
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def test_loader_error_string(error_filename, verbose=False):
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try:
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list(yaml.load_all(open(error_filename, 'rb').read(), yaml.FullLoader))
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except yaml.YAMLError, exc:
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if verbose:
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print "%s:" % exc.__class__.__name__, exc
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else:
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raise AssertionError("expected an exception")
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test_loader_error_string.unittest = ['.loader-error']
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def test_loader_error_single(error_filename, verbose=False):
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try:
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yaml.load(open(error_filename, 'rb').read(), yaml.FullLoader)
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except yaml.YAMLError, exc:
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if verbose:
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print "%s:" % exc.__class__.__name__, exc
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else:
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raise AssertionError("expected an exception")
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test_loader_error_single.unittest = ['.single-loader-error']
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def test_emitter_error(error_filename, verbose=False):
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events = list(yaml.load(open(error_filename, 'rb'),
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Loader=test_emitter.EventsLoader))
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try:
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yaml.emit(events)
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except yaml.YAMLError, exc:
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if verbose:
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print "%s:" % exc.__class__.__name__, exc
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else:
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raise AssertionError("expected an exception")
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test_emitter_error.unittest = ['.emitter-error']
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def test_dumper_error(error_filename, verbose=False):
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code = open(error_filename, 'rb').read()
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try:
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import yaml
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from StringIO import StringIO
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exec code
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except yaml.YAMLError, exc:
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if verbose:
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print "%s:" % exc.__class__.__name__, exc
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else:
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raise AssertionError("expected an exception")
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test_dumper_error.unittest = ['.dumper-error']
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if __name__ == '__main__':
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import test_appliance
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test_appliance.run(globals())
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