2 ms·

> This also means that very long-lived platforms will probably be forced to upgrade that library every half year or so in line with the development of rust. As

by gpm 6y ago

> This also means that very long-lived platforms will probably be forced to upgrade that library every half year or so in line with the development of rust. As a security library... you really ought to be updating it every half year of so. This has nothing to do with rust though. Rust maintains full backwards compatibility, so even if you upgrade the compiler (which is unlikely on long lived platforms) and not the library nothing breaks. Nor is it necessarily the case that upgrading the library will require updating rust (though this isn't what you appear to be complaining about). Not only is it a build time dependency (that you don't even need to install if you are on common platforms which ave prebuilt binaries), but they are explicitly testing against a particular fixed old version of rust as well as recent ones: https://github.com/pyca/cryptography/blob/main/.github/workflows/ci.yml#L145 https://github.com/pyca/cryptography/blob/main/.github/workf... > I'd say such an initiative needs a long-term supported version of rust, similar to C99 or so. This describes every version of rust since 1.0. Rust is fully backwards compatible, unlike new C standards. > Do we have anyone committed to providing a stable rust environment for these cases? Yes, the entire rust team... > Especially considering that rust has no ABI for dynamic libraries. This is... rather irrelevant? Technically it does have support for the C abi for dynamic libraries though.

choeger 6y ago
I think you should reconsider the actual problem, if you do not understand it. The fact that rustc is backwards compatible is great, sure. But it does not solve the problem of distributors. Say you have libfoo-1.0 that uses rust and cargo 1.2 . A distributor that now releases their linux version and wants to ship libfoo-1.0 must consider the requirements for supporting it. This support usually outlives the upstream support. If libfoo-1.0 uses C, for instance, it is highly likely that a distributor can backport any security-relevant changes from libfoo-1.1, 1.2, and later into 1.0. In the case of rust there are two uncertainties creeping in: One is the highly dynamic nature of cargo dependencies. libfoo might depend on a myriad of crates transitively and rust simply is too young to provide any experience in how long they will be available or supported. And no, it is generally not a good idea to update to new feature releases for security updates. This is something that stable distributions explicitly try to avoid. So our distributor now must consider if changes in libfoo-1.2 pulled in changes via cargo that cannot be easily backported because they are feature releases or have a dependency on a newer version of rust. The second problem is the compiler itself. Any change in libfoo-1.2 might require a newer version of rust. It is great that they want to be backwards compatible but now our distributor must consider upgrading a substantial piece of software during the support period (and testing the backwards compatibility, of course) just to backport a security fix. Please don't get me wrong, I really like rust and I think these problems can be solved. But I also like stable software and all these languages with their package repositories seem to simply ignore everything that's older than one or two years. If rust wants to become a new C, which I would very much like, it needs to demonstrate a certain stability.
- gpm 6y ago
  I think you are missing the fact that the solutions are already in place for all of this. > One is the highly dynamic nature of cargo dependencies. libfoo might depend on a myriad of crates transitively and rust simply is too young to provide any experience in how long they will be available or supported. And no, it is generally not a good idea to update to new feature releases for security updates. This is something that stable distributions explicitly try to avoid. crates.io is designed so that dependencies put up on it remain available forever, and that the only other cargo related dependencies also have to be hosted on crates.io - solving the availability problem. Of course if you're trying to backport a security fix to an old version of a transitive dependency that (like the non-transitive dependency) is no longer supported, you do have to make that backport. Once you make that backport it's easy to update the version of the transitive dependency with a [patch] section in the top level Cargo.toml. > The second problem is the compiler itself. Any change in libfoo-1.2 might require a newer version of rust. This is already mitigated in multiple ways. As discussed before, people do make sure to support old versions of compilers, you don't need to have a compiler on your target platform anyways. But moreover, the amount new language features make backporting difficult is dwarfed by the amount that internal library changes do.
  - kzhukov 6y ago
    What I don't really like in cargo is its' overcentralized and author-centric approach. What if some of your dependencies relies on the crate, which author doesn't support anymore and doesn't even accept patches? You will basically have to maintain a fork either with a different name (because you can't push it to crates.io) or have a patched version which you also can't push and have to manually update every Cargo.toml of every dependency in your project to use your fork. And what if you have not only one Rust project in your complex system? You will have to update or vendor everything. This is a real maintenance hell. While in C/C++ I can just build a fork as dynamic library and put it to the system image or to the own package manager repo. I mean for sure Cargo is great for small hobby projects, but for the big complicated enterprise projects it's not really suitable. Even Google doesn't use Cargo in Fuchsia and vendors everything.

by gpm 6y ago

choeger 6y ago

I think you should reconsider the actual problem, if you do not understand it. The fact that rustc is backwards compatible is great, sure. But it does not solve the problem of distributors. Say you have libfoo-1.0 that uses rust and cargo 1.2 . A distributor that now releases their linux version and wants to ship libfoo-1.0 must consider the requirements for supporting it. This support usually outlives the upstream support. If libfoo-1.0 uses C, for instance, it is highly likely that a distributor can backport any security-relevant changes from libfoo-1.1, 1.2, and later into 1.0. In the case of rust there are two uncertainties creeping in: One is the highly dynamic nature of cargo dependencies. libfoo might depend on a myriad of crates transitively and rust simply is too young to provide any experience in how long they will be available or supported. And no, it is generally not a good idea to update to new feature releases for security updates. This is something that stable distributions explicitly try to avoid. So our distributor now must consider if changes in libfoo-1.2 pulled in changes via cargo that cannot be easily backported because they are feature releases or have a dependency on a newer version of rust. The second problem is the compiler itself. Any change in libfoo-1.2 might require a newer version of rust. It is great that they want to be backwards compatible but now our distributor must consider upgrading a substantial piece of software during the support period (and testing the backwards compatibility, of course) just to backport a security fix. Please don't get me wrong, I really like rust and I think these problems can be solved. But I also like stable software and all these languages with their package repositories seem to simply ignore everything that's older than one or two years. If rust wants to become a new C, which I would very much like, it needs to demonstrate a certain stability.

gpm 6y ago
I think you are missing the fact that the solutions are already in place for all of this. > One is the highly dynamic nature of cargo dependencies. libfoo might depend on a myriad of crates transitively and rust simply is too young to provide any experience in how long they will be available or supported. And no, it is generally not a good idea to update to new feature releases for security updates. This is something that stable distributions explicitly try to avoid. crates.io is designed so that dependencies put up on it remain available forever, and that the only other cargo related dependencies also have to be hosted on crates.io - solving the availability problem. Of course if you're trying to backport a security fix to an old version of a transitive dependency that (like the non-transitive dependency) is no longer supported, you do have to make that backport. Once you make that backport it's easy to update the version of the transitive dependency with a [patch] section in the top level Cargo.toml. > The second problem is the compiler itself. Any change in libfoo-1.2 might require a newer version of rust. This is already mitigated in multiple ways. As discussed before, people do make sure to support old versions of compilers, you don't need to have a compiler on your target platform anyways. But moreover, the amount new language features make backporting difficult is dwarfed by the amount that internal library changes do.
- kzhukov 6y ago
  What I don't really like in cargo is its' overcentralized and author-centric approach. What if some of your dependencies relies on the crate, which author doesn't support anymore and doesn't even accept patches? You will basically have to maintain a fork either with a different name (because you can't push it to crates.io) or have a patched version which you also can't push and have to manually update every Cargo.toml of every dependency in your project to use your fork. And what if you have not only one Rust project in your complex system? You will have to update or vendor everything. This is a real maintenance hell. While in C/C++ I can just build a fork as dynamic library and put it to the system image or to the own package manager repo. I mean for sure Cargo is great for small hobby projects, but for the big complicated enterprise projects it's not really suitable. Even Google doesn't use Cargo in Fuchsia and vendors everything.