![]() The value corresponds to a special user without any system rights: nobody, as you can see in uid/gid in the output above. It is shown as 65534 only because this value is used for any unknown id:įunctions getuid(), getgid() returns the value from /proc/sys/kernel/overflowgid for uids/gids which does not have a mapping. What you have done with ~]$ newuidmap 7134 65534 5000 1 was association of userid 5000 in a parent namespace with uid 65534 in a child namespace, but the process still runs as root. In this case the user root is left unknown for the child user namespace: ~ $ id You can try some other mappings, like newuidmap 18526 1 0 1 and see that it is applied to the child user namespace, not the parent one.Įxample 2: Now we does not set a mapping for root: arksnote linux-namespaces # newuidmap 181Īrksnote linux-namespaces # cat /proc/18868/uid_map Here's what happens to the child namespace: ~ $ id Now let's link root from parent namespace with some id (0 in this case) in a child namespace: arksnote linux-namespaces # newuidmap 18526 0 0 1Īrksnote linux-namespaces # cat /proc/18526/uid_map arksnote linux-namespaces # unshare -U ~ $ id Suppose we have created a child user namespace. They of course should be mapped onto the values in the parent namespace, otherwise geteuid() function will fail.Įxample 1. You can call setuid(2) or seteuid(2) from within a child namespace to change the credentials to some other credentials from the same user namespace.The mapping links ids in a child namespace to ids in its parent namespace, not the opposite way. you can make a small fix in an example from user_namespaces(7)) which updates uid_map/gid_map before 'exec', the update will succeed.īut when I run a process from within the new namespace it still seems Still, if you compile some application (e.g. This happens because unshare calls 'exec bash' before returing the control to the user and you loose the necessary capabilities, thus you cannot change uid_map/gid_map from within user namespace. Note that a call to execve(2) will cause a process'sĬapabilities to be recalculated in the usual way (see Starts out with a complete set of capabilities in the new user ![]() The child process created by clone(2) with the CLONE_NEWUSER flag Newuidmap: write to uid_map failed: Operation not permitted
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