SSLContext._load_windows_store_certs fails with PermissionError

[zooba]

BPO	27114
Nosy	@pfmoore, @tjguk, @zware, @zooba
Files	27114_1.patch

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = 'https://github.com/zooba'
closed_at = <Date 2016-05-26.19:28:09.035>
created_at = <Date 2016-05-24.22:24:35.621>
labels = ['type-bug', 'OS-windows']
title = 'SSLContext._load_windows_store_certs fails with PermissionError'
updated_at = <Date 2016-05-26.19:28:09.034>
user = 'https://github.com/zooba'

bugs.python.org fields:

activity = <Date 2016-05-26.19:28:09.034>
actor = 'steve.dower'
assignee = 'steve.dower'
closed = True
closed_date = <Date 2016-05-26.19:28:09.035>
closer = 'steve.dower'
components = ['Windows']
creation = <Date 2016-05-24.22:24:35.621>
creator = 'steve.dower'
dependencies = []
files = ['42979']
hgrepos = []
issue_num = 27114
keywords = ['patch']
message_count = 5.0
messages = ['266285', '266286', '266448', '266449', '266450']
nosy_count = 5.0
nosy_names = ['paul.moore', 'tim.golden', 'python-dev', 'zach.ware', 'steve.dower']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue27114'
versions = ['Python 2.7', 'Python 3.5', 'Python 3.6']

[zooba]

In some restricted server scenarios, it is not possible to enumerate the Windows machine certificate store. A PermissionError is raised and the operation aborted.

Instead, we should simply return no certificates from _load_windows_store_certs. This will most likely cause the SSL request to fail (as the certificate cannot be verified), but it allows the use of SSL_CERT_FILE to use certificates from a local file. Without handling the PermissionError, it doesn't matter whether the environment variable is set or not - we simply fail every time.

[zooba]

Added a patch against 3.5 that handles PermissionError and warns about the failure.

I think this should be applied against 2.7, 3.5 and 3.6, and that it's unfortunately untestable (without adding extra API to force it to fail). Any concerns?

[python-dev]

New changeset 40f3f2b27112 by Steve Dower in branch '2.7':
Issue bpo-27114: Fix SSLContext._load_windows_store_certs fails with PermissionError
https://hg.python.org/cpython/rev/40f3f2b27112

[python-dev]

New changeset 29f163db229e by Steve Dower in branch '3.5':
Issue bpo-27114: Fix SSLContext._load_windows_store_certs fails with PermissionError
https://hg.python.org/cpython/rev/29f163db229e

New changeset eaee5aed6fbc by Steve Dower in branch 'default':
Issue bpo-27114: Fix SSLContext._load_windows_store_certs fails with PermissionError
https://hg.python.org/cpython/rev/eaee5aed6fbc

[zooba]

One slight change to the patch for 2.7 - has to catch OSError.

Just realised that I forgot to mention the reason we shouldn't just let the exception propagate out is that we then never load certificates specified by the SSL_CERT_FILE variable. Handling the exception allows a workaround.

If the exception occurs and no other certificates have been provided, it seems certain that a later operation is going to fail with a much more useful message (i.e. unverifiable connection, or whatever it says). There are also libraries (I think urllib is the one that was causing me actual trouble) that keep retrying the call when it fails, and all of those would need to be updated to handle this error.

The docs don't specify potential exceptions, so I see only good by not raising an exception here.