It would be useful if a Dart script could change its user and group ids.

Is there an equivalent on Windows?

cc @sgjesse.
cc @skabet.
cc @whesse.
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It would be useful to us to be able to set it; inline with the script would be nice. I don't program in windows so I'm not qualified to mention an alternative.

Added this to the M8 milestone.

On Windows the permissions are defined in a structural ACL object which is much more complicated than the Linux permissions.

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Hi again

After reading this again I - of cause - misunderstood your question. This is not a matter of changing the permissions, but on supporting the setuid /setgid bits on a Dart script.

I assume you would like the following:

  Create test.dart
  $ chown test_user.test_group test.dart
  $ chmod 4755 test.dart
  $ dart test.dart

The last command should then run the Dart script with the effective user ID/effective group ID test_user/test_group.

However for this to work the permissions needs to be set on the Dart executable.

Maybe the Dart executable can do some tricks to handle this. Seems that shell-scripts does not allow this on Linux (for security reasons), but e.g. perl supports it.

We still need setuid/setgid/seteuid/setegid/getuid/geteuid methods in dart:io which will have no counterparts on Windows.

Regarding Windows the only thing available in this area is as far as I can see "run as", see http://support.microsoft.com/kb/305780. I don't think we can use that here though.

This comment was originally written by andre.kaufm...@gmail.com

Please add this ASAP.

We need a way for a HTTP server to start with root permissions to listen on port 80. Then revert back the server permission to a regular user for security reasons.

Thank you in advance.

Running with root permissions sounds like a risky scenario. I would suggest looking into one of the followings:

• Run your service as a daemon (like apache and nginx does).
• Change capabilities (something along the lines of setcap 'cap_net_bind_service=+ep' /path/to/dart)
• Iptable forward to e.g. port 8080.

As Soeren mentioned above, there are some security concerns with set*id and scripts.

• Anders

This comment was originally written by yu.as...@gmail.com

Can you please separate the discussions about two issues?

(1) Provide a way to make setuid and related system calls, or possibly their high-level abstraction.
Because these system calls have different semantics in different Unix OSes (see https://www.usenix.org/legacy/event/sec02/full_papers/chen/chen.pdf), it might be useful for Dart to provide some high-level abstraction for them, if it is possible.

(2) Allow a Dart script to be executed with the set-user-ID mode bit or the set-group-ID mode bit set.

I am not sure which of the above the OP meant by “DartVM Feature Request: setuid / setguid”. Supporting (1) and supporting (2) are pretty much disjoint tasks, although they are sometimes used in combination.

OP here. I was asking about (1) API calls or higher level abstraction. Though now we have other ways of doing this.

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This comment was originally written by @kaendfinger

If you need it now on Unix/Mac, you can use my syscall package:

https://pub.dartlang.org/packages/syscall

setUserId and setGroupId is what you want.

This comment was originally written by @kaendfinger

@kasperl @­kevmoo @­codefu

I plan on implementing setuid/getuid support. I need guidance on what a good naming scheme would be:

Platform.uid with a getter and setter vs. Platform.getUid and Platform.setUid vs. Platform.userId with getter and setter

Support:
Unix-only (includes Mac too): Throws exception on Windows.

This comment was originally written by @seaneagan

@kaendfinger, issue #22037 requests adding the uid/gid getters. Getters/setters definitely are my preference. It might make sense to put them at the top-level of dart:io next to pid, and the getters will also need to be on FileStat. I like uid and gid, given that we already have pid.

And here is a high-level permissions API which would be nice to have as well:

https://github.com/seaneagan/which.dart/blob/master/lib/src/has_permission.dart

This comment was originally written by @kaendfinger

I didn't consider that, I like it. I am just always cautious to add top-level variables, but it is definitely appropriate in this case.

As for the permissions, I'll have to look into this next :)