restore: do mount proc in usernsd on certain conditions #2600
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| int fd, ret; | ||
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| if ((root_ns_mask & CLONE_NEWUSER) && !(root_ns_mask & CLONE_NEWNS)) | ||
| fd = ret = userns_call(userns_mount_proc, UNS_FDOUT, NULL, sizeof(NULL), -1); |
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will it be mounted in the target pid namespace?
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No i don't think it will be mounted and it's gonna be rejected. I fixed this now. The corner case is only when the user namespace is isolated while keeping both mount namespace and pid namespace be shared with host. If either of two namespaces are isolated, the proc fs will be mounted successfully.
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If a target workload is restored in just separate userns and pid namespaces, userns_mount_proc will fail, because the current process doesn't have CAP_SYS_ADMIN in the current mount namespace. The only way to workaround that is to mount proc from usernsd, and the userns mount callback has to enter the target pid namespace before mounting proc.
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Rebased to criu-dev |
When the user namespace is separate from both pid and mount namespace in the given task, cr-restore will fail to mount the procfs in the new user namespace because of the loss of privileges. Delegate usernsd to do the mount job if that corner case arises. Signed-off-by: Yiyang Wu <toolmanp@tlmp.cc>
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A friendly reminder that this PR had no activity for 30 days. |
When only the user namespace is isolated in the given task, cr-restore will fail to mount the procfs in the new user namespace because of the loss of privileges.
Delegate usernsd to do the mount job if that corner case arises.
Fixes: #2597