7fc29c1435
Aside from unconditionally unlocking the OS thread even if restoring the thread's network namespace fails, func (*networkNamespace).InvokeFunc() correctly implements invoking a function inside a network namespace. This is far from obvious, however. func InitOSContext() does much of the heavy lifting but in a bizarre fashion: it restores the initial network namespace before it is changed in the first place, and the cleanup function it returns does not restore the network namespace at all! The InvokeFunc() implementation has to restore the network namespace explicitly by deferring a call to ns.SetNamespace(). func InitOSContext() is a leaky abstraction taped to a footgun. On the one hand, it defensively resets the current thread's network namespace, which has the potential to fix up the thread state if other buggy code had failed to maintain the invariant that an OS thread must be locked to a goroutine unless it is interchangeable with a "clean" thread as spawned by the Go runtime. On the other hand, it _facilitates_ writing buggy code which fails to maintain the aforementioned invariant because the cleanup function it returns unlocks the thread from the goroutine unconditionally while neglecting to restore the thread's network namespace! It is quite scary to need a function which fixes up threads' network namespaces after the fact as an arbitrary number of goroutines could have been scheduled onto a "dirty" thread and run non-libnetwork code before the thread's namespace is fixed up. Any number of (not-so-)subtle misbehaviours could result if an unfortunate goroutine is scheduled onto a "dirty" thread. The whole repository has been audited to ensure that the aforementioned invariant is never violated, making after-the-fact fixing up of thread network namespaces redundant. Make InitOSContext() a no-op on Linux and inline the thread-locking into the function (singular) which previously relied on it to do so. func ns.SetNamespace() is of similarly dubious utility. It intermixes capturing the initial network namespace and restoring the thread's network namespace, which could result in threads getting put into the wrong network namespace if the wrong thread is the first to call it. Delete it entirely; functions which need to manipulate a thread's network namespace are better served by being explicit about capturing and restoring the thread's namespace. Rewrite InvokeFunc() to invoke the closure inside a goroutine to enable a graceful and safe recovery if the thread's network namespace could not be restored. Avoid any potential race conditions due to changing the main thread's network namespace by preventing the aforementioned goroutines from being eligible to be scheduled onto the main thread. Signed-off-by: Cory Snider <csnider@mirantis.com> |
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| docker-bake.hcl | ||
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| LICENSE | ||
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| NOTICE | ||
| README.md | ||
| ROADMAP.md | ||
| SECURITY.md | ||
| TESTING.md | ||
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| VENDORING.md | ||
The Moby Project
Moby is an open-source project created by Docker to enable and accelerate software containerization.
It provides a "Lego set" of toolkit components, the framework for assembling them into custom container-based systems, and a place for all container enthusiasts and professionals to experiment and exchange ideas. Components include container build tools, a container registry, orchestration tools, a runtime and more, and these can be used as building blocks in conjunction with other tools and projects.
Principles
Moby is an open project guided by strong principles, aiming to be modular, flexible and without too strong an opinion on user experience. It is open to the community to help set its direction.
- Modular: the project includes lots of components that have well-defined functions and APIs that work together.
- Batteries included but swappable: Moby includes enough components to build fully featured container system, but its modular architecture ensures that most of the components can be swapped by different implementations.
- Usable security: Moby provides secure defaults without compromising usability.
- Developer focused: The APIs are intended to be functional and useful to build powerful tools. They are not necessarily intended as end user tools but as components aimed at developers. Documentation and UX is aimed at developers not end users.
Audience
The Moby Project is intended for engineers, integrators and enthusiasts looking to modify, hack, fix, experiment, invent and build systems based on containers. It is not for people looking for a commercially supported system, but for people who want to work and learn with open source code.
Relationship with Docker
The components and tools in the Moby Project are initially the open source components that Docker and the community have built for the Docker Project. New projects can be added if they fit with the community goals. Docker is committed to using Moby as the upstream for the Docker Product. However, other projects are also encouraged to use Moby as an upstream, and to reuse the components in diverse ways, and all these uses will be treated in the same way. External maintainers and contributors are welcomed.
The Moby project is not intended as a location for support or feature requests for Docker products, but as a place for contributors to work on open source code, fix bugs, and make the code more useful. The releases are supported by the maintainers, community and users, on a best efforts basis only, and are not intended for customers who want enterprise or commercial support; Docker EE is the appropriate product for these use cases.
Legal
Brought to you courtesy of our legal counsel. For more context, please see the NOTICE document in this repo.
Use and transfer of Moby may be subject to certain restrictions by the United States and other governments.
It is your responsibility to ensure that your use and/or transfer does not violate applicable laws.
For more information, please see https://www.bis.doc.gov
Licensing
Moby is licensed under the Apache License, Version 2.0. See LICENSE for the full license text.