user_namespaces(7): obsolete comment about system time

user_namespaces(7): obsolete comment about system time

[Léo Stefanesco]

Hi,

In the man7.org version of the man page for user_namespaces(7), it reads:

there are many privileged operations that affect resources that are
not associated with any
namespace type, for example, changing the system time (governed by CAP_SYS_TIME)

which is not consistent with time_namespaces(7).

Cheers,
Léo

Re: user_namespaces(7): obsolete comment about system time

[Michael Kerrisk (man-pages)]

Hello Léo

On 5/31/20 5:26 PM, Léo Stefanesco wrote:
> Hi,
> 
> In the man7.org version of the man page for user_namespaces(7), it reads:
> 
>    there are many privileged operations that affect
>    resources that are not associated with any namespace type,
>    for example, changing the system time
>    (governed by CAP_SYS_TIME)
> 
> which is not consistent with time_namespaces(7).

In fact, strictly peaking the text still is correct, even after
the arrival of time namespaces.

Time namespaces virtualize only the boot-time and monotonic clocks,
not the "real time" (i.e., calendar time), which is the time
referred in the passage you quote.

That said, the text is perhaps now a little misleading, and
a little clarification would help. I changed the text to:

    there are many privileged operations that affect
    resources are not associated with any namespace type,
    for example, changing the system **(i.e., calendar)** time 
    (governed by CAP_SYS_TIME)

Thanks for your report!

Michael


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/