pkg/netns: NewNS() check if file name already exists #1381
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[APPROVALNOTIFIER] This PR is APPROVED This pull-request has been approved by: Luap99 The full list of commands accepted by this bot can be found here. The pull request process is described here
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@mheon PTAL |
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pkg/netns/netns_linux.go
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| _, err := rand.Reader.Read(b) | ||
| if err != nil { | ||
| return nil, fmt.Errorf("failed to generate random netns name: %v", err) | ||
| for i := 0; i < 1000000; i++ { |
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Maybe a little lower on the iteration count here? 10,000 or so?
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Yeah honestly not sure what a good number is, 10k would be fine for me as well.
The code picks a random name but never checked if this name was already in use. If the RNG generates the same name again we will end up with containers sharing the same netns which can be very bad. It is very unlikely to happen but this the only explanation I find for containers/podman#17903. Signed-off-by: Paul Holzinger <[email protected]>
Because we do not not unlock the OS thread it will be killed by the runtime and not be reused for go 1.10+. Therefore there is no point in joining the original netns back which never worked as rootless. Go 1.10 is EOL for years and our code doesn't compile on such old versions anyway so it is safe to remove. Signed-off-by: Paul Holzinger <[email protected]>
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LGTM, the chance of this happening is very slim, but over 10,000 times yikes. |
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/lgtm |
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I made a change in c/common[1] to prevent duplicates in netns names. This now causes problem in podman[2] where the rootless netns will no longer work after the netns got invalid but the underlying path still exists. AFAICT this happens when the podman pause process got killed and we are now in a different user namespace. While I do not know what causes this, this commit should make it at least possible to recover from this situation automatically as it used to be before[1]. the problem with that is that containers started before it will not be able to talk to contianers started after this. A restart of the previous container will fix it but this was also the case before. [NO NEW TESTS NEEDED] [1] containers/common#1381 [2] containers#17903 (comment) Signed-off-by: Paul Holzinger <[email protected]>
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The code picks a random name but never checked if this name was already
in use. If the RNG generates the same name again we will end up
with containers sharing the same netns which can be very bad.
It is very unlikely to happen but this the only explanation I find for
containers/podman#17903.
pkg/netns: remove old pre go 1.10 workaround
Because we do not not unlock the OS thread it will be killed by the
runtime and not be reused for go 1.10+. Therefore there is no point in
joining the original netns back which never worked as rootless.
Go 1.10 is EOL for years and our code doesn't compile on such old
versions anyway so it is safe to remove.