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Wait for reexec to finish when fileOutput is nil #7292

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merged 1 commit into from
Aug 18, 2020
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Wait for reexec to finish when fileOutput is nil #7292

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10 changes: 10 additions & 0 deletions pkg/rootless/rootless_linux.go
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Original file line number Diff line number Diff line change
Expand Up @@ -233,6 +233,11 @@ func becomeRootInUserNS(pausePid, fileToRead string, fileOutput *os.File) (_ boo
if pid < 0 {
return false, -1, errors.Errorf("cannot re-exec process")
}
defer func() {
if retErr != nil {
C.reexec_in_user_namespace_wait(pidC, 0)
}
}()

uids, gids, err := GetConfiguredMappings()
if err != nil {
Expand Down Expand Up @@ -294,6 +299,11 @@ func becomeRootInUserNS(pausePid, fileToRead string, fileOutput *os.File) (_ boo
}

if fileOutput != nil {
ret := C.reexec_in_user_namespace_wait(pidC, 0)
if ret < 0 {
return false, -1, errors.New("error waiting for the re-exec process")
}

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IDK, but will ask. We have a couple of other returns before the end of this function at lines 311 and 315. Do we need to call there too?

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I think we probably should. Can we defer a function that runs reexec_in_user_namespace_wait? Would there be a problem if we ran it against the same PID in rapid succession?

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@jdieter if we did the defer, we'd need to capture the status of the call and return appropriately based on that. I'm not sure that's doable with defer, @mheon or @vrothberg might have some smarter thoughts on that or my question in general.

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we could probably record the exit error and run it only when retErr != nil. What do you think?

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Makes sense to me.

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Ok, I'm not very proficient in Go, but tell me if my lastest push has what you're looking for. I've setup a deferred function that waits for the child if retErr != nil. I don't bother with the return value from reexec_in_user_namespace_wait because we presumably are more interested in passing whatever error is causing us to bail.

return true, 0, nil
}

Expand Down