Rather than enforce lowercase paths for all drivers, support for
case-sensitivity has been deferred to the driver. There are a few caveats to
this approach:
1. There are possible security implications for tags that only differ in their
case. For instance, a tag "A" may be equivalent to tag "a" on certain file
system backends.
2. All system paths should not use case-sensitive identifiers where possible.
This might be problematic in a blob store that uses case-sensitive ids. For
now, since digest hex ids are all case-insensitive, this will not be an issue.
The recommend workaround is to not run the registry on a case-insensitive
filesystem driver in security sensitive applications.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
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