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fix(libcontainer) no_pivot args is not used #2923

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merged 7 commits into from
Oct 29, 2024

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xujihui1985
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fix the problem that no_pivot args is not used when create container when we prepare rootfs with chroot, we should move_mount the rootfs before chroot, otherwise we will not able to use the new rootfs when exec into the container

@xujihui1985
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@udzura This PR addresses the issue where the no_pivot argument is not recognized. This argument is crucial in environments where the pivot_root syscall is not permitted, such as when running containers within containers.

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udzura commented Sep 22, 2024

I understand what this PR aim to do 👍 But I have no privilege to merge this. I guess you've mistaken me for someone!

@xujihui1985
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I understand what this PR aim to do 👍 But I have no privilege to merge this. I guess you've mistaken me for someone!

@udzura sorry for bother you, could you help to involve someone that is able to have a look at this PR? Really appreciate.

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utam0k commented Sep 23, 2024

I'll check this PR. Thanks for your first contribution!

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utam0k commented Sep 23, 2024

@xujihui1985 May I ask you to add an integration test for this PR?
https://containers.github.io/youki/developer/e2e/rust_oci_test.html

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@xujihui1985 May I ask you to add an integration test for this PR?

https://containers.github.io/youki/developer/e2e/rust_oci_test.html

sure, I'd like to learn how to add integrate test

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utam0k commented Sep 23, 2024

sure, I'd like to learn how to add integrate test

I can help you if you need ;)

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YJDoc2 commented Sep 23, 2024

Hey @xujihui1985 Thanks for your contribution! May I ask you to also take a look at #2597 , which also deals with no_pivot and the create and run commands. Can you check if you need to pick up any changes from there to here? Thanks.

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Hey @xujihui1985 Thanks for your contribution! May I ask you to also take a look at #2597 , which also deals with no_pivot and the create and run commands. Can you check if you need to pick up any changes from there to here? Thanks.

Hi @YJDoc2 I just noticed a similar pull request that addresses this issue and is almost identical to my approach. However, the only problem is that the chroot implementation is incorrect. I can build upon his PR, fix the chroot issue, and include credit for his work.

Vanient and others added 2 commits September 27, 2024 09:04
Move the rootfs to the root of the host filesystem before chrooting,
this is equivalent to pivot_root, if don't move mount first, we will
not see the new rootfs when exec into the container

Signed-off-by: xujihui1985 <[email protected]>
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@YJDoc2 I have pick the change from commit #2597, I will continue work on integration test

…havior

Move the mount operation to occur before calling chroot to better simulate the effect of pivot_root.
Add a check to confirm if the current process is running inside an isolated mount namespace, ensuring proper mount handling.

Signed-off-by: xujihui1985 <[email protected]>
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xujihui1985 commented Oct 8, 2024

@udzura, @YJDoc2 Hi, I have implemented the integration test in commit c82496b. For now, I copied and reused some utility functions, like test_inside_container -> test_inside_container_with_no_pivot, since create_container currently doesn't allow setting the necessary arguments. and change this function will cause lots of change in current testcase. This was done to verify if the test works as expected. Once the test is reviewed and approved, I'll refactor the functions accordingly.

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That's what I expected. But I want @YJDoc2 to review it, too.

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sure, let me know if any improvements are possible

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I'll take a look at this soon. Thanks!

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Hey, the overall implementation looks good, I have a couple of nitpick comments, please take a look at them.

As for the tests, I feel that the added test is ok, but we need to refactor the test_inside... function to avoid duplication. I'll think on a way for more "ergonomic" imple, but if you can think of something, go ahead.

I'm also thinking we should have this functionality in test_outside.. so we can also test for container create,run,delete with no_pivot. WDYT? Would that be useful?

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/cc @Gekko0114

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Hey, the overall implementation looks good, I have a couple of nitpick comments, please take a look at them.

As for the tests, I feel that the added test is ok, but we need to refactor the test_inside... function to avoid duplication. I'll think on a way for more "ergonomic" imple, but if you can think of something, go ahead.

I'm also thinking we should have this functionality in test_outside.. so we can also test for container create,run,delete with no_pivot. WDYT? Would that be useful?

@YJDoc2 I believe the test_outside_container with the no-pivot option doesn't behave any differently from the test with the option enabled. It's unclear what to assert when testing outside the container with the no-pivot option because, outside of a container mount namespace, chroot and pivot_root have no noticeable effect. Any idea?

Signed-off-by: xujihui1985 <[email protected]>
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@YJDoc2 Do you think it would be better to refactor the test_inside... function in a separate PR? It will involve a lot of changes as the change of the signature

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@YJDoc2 Do you think it would be better to refactor the test_inside... function in a separate PR? It will involve a lot of changes as the change of the signature

@YJDoc2 Hi, would you like to proceed the PR or wait until the function been refactored?

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YJDoc2 commented Oct 22, 2024

I believe the test_outside_container with the no-pivot option doesn't behave any differently from the test with the option enabled. It's unclear what to assert when testing outside the container with the no-pivot option because, outside of a container mount namespace, chroot and pivot_root have no noticeable effect.

I mentioned test_outside_container as that is another test fn we use, but I hadn't thought this in detail. My main intention here was that to verify via e2e that basic commands such as start, delete, run etc work properly with the no_pivot, so whatever does the trick, works.

@YJDoc2 Hi, would you like to proceed the PR or wait until the function been refactored?

I think the refactoring should be done in separate PR as that will be a big change, I'll do a final review, hopefully today, and if all's ok then merge, after which you can start with that refactoring.

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xujihui1985 commented Oct 28, 2024

I believe the test_outside_container with the no-pivot option doesn't behave any differently from the test with the option enabled. It's unclear what to assert when testing outside the container with the no-pivot option because, outside of a container mount namespace, chroot and pivot_root have no noticeable effect.

I mentioned test_outside_container as that is another test fn we use, but I hadn't thought this in detail. My main intention here was that to verify via e2e that basic commands such as start, delete, run etc work properly with the no_pivot, so whatever does the trick, works.

@YJDoc2 Hi, would you like to proceed the PR or wait until the function been refactored?

I think the refactoring should be done in separate PR as that will be a big change, I'll do a final review, hopefully today, and if all's ok then merge, after which you can start with that refactoring.

@YJDoc2 Hi, hope everything goes well with you, if there is anything I can improve for this PR, please let me know as

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Hey, I have a couple of nits, but nothing that blocks the merge. I'm approving this PR, and you can address the nits in the PR you'll make to refactor the test function. I'm not merging this right away, in case you want to reply something, but if no reply, I'll merge it by tomorrow.

Comment on lines -346 to -351
if namespaces.get(LinuxNamespaceType::Mount)?.is_some() {
// change the root of filesystem of the process to the rootfs
syscall.pivot_rootfs(rootfs_path).map_err(|err| {
tracing::error!(?err, ?rootfs_path, "failed to pivot root");
InitProcessError::SyscallOther(err)
})?;
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nit: we should move the comment above this to the function where we are doing this

let res = Command::new(get_runtime_path())
// set stdio so that we can get o/p of runtimetest
// in test_inside_container function
fn create_container_command<P: AsRef<Path>>(id: &str, dir: P, with_pivot_root: bool) -> Command {
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nit: I feel a better name for argument would be no_pivot or pivot_root . with_pivot_root feels like a path for pivoting a root to. wdyt?

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YJDoc2 commented Oct 28, 2024

@YJDoc2 Hi, hope everything goes well with you, if there is anything I can improve for this PR, please let me know as

Hey, sorry, I was busy with work and some other stuff and couldn't get to any of this. This is good to merge, and I have approved this. I will wait till tom if you have any replies to my comments, otherwise I'll merge this as-is, and you can address the nits in your next PR.

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@YJDoc2 Hi, hope everything goes well with you, if there is anything I can improve for this PR, please let me know as

Hey, sorry, I was busy with work and some other stuff and couldn't get to any of this. This is good to merge, and I have approved this. I will wait till tom if you have any replies to my comments, otherwise I'll merge this as-is, and you can address the nits in your next PR.

thanks for your reply. I will continue working on the refactoring. Cheers

@YJDoc2 YJDoc2 merged commit d071596 into youki-dev:main Oct 29, 2024
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YJDoc2 commented Oct 29, 2024

I will continue working on the refactoring.

Thank you! Please address the nitpicks in your next PR.

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6 participants