On 01/02/2015 07:04 PM, Mike Frysinger wrote: > The setns(2) man page already mentions that CLONE_NEWPID may only be > used with descendant namespaces, but this nuance could be listed in > a few more places so it is not missed. Nice additions! Thanks, Mike. Patch applied. Cheers, Michael > > Signed-off-by: Mike Frysinger <vapier@xxxxxxxxxx> > --- > man2/setns.2 | 7 ++++++- > man7/pid_namespaces.7 | 10 ++++++++++ > 2 files changed, 16 insertions(+), 1 deletion(-) > > diff --git a/man2/setns.2 b/man2/setns.2 > index 926842b..3e6c4a5 100644 > --- a/man2/setns.2 > +++ b/man2/setns.2 > @@ -55,7 +55,7 @@ must refer to a mount namespace. > .TP > .BR CLONE_NEWPID " (since Linux 3.8)" > .I fd > -must refer to a PID namespace. > +must refer to a descendant PID namespace. > .TP > .BR CLONE_NEWUSER " (since Linux 3.8)" > .I fd > @@ -157,6 +157,11 @@ refers to a namespace whose type does not match that specified in > There is problem with reassociating > the thread with the specified namespace. > .TP > +.\" See kernel/pid_namespace.c::pidns_install() [kernel 3.18 sources] > +.B EINVAL > +The caller tried to join an ancestor (parent, grandparent, etc...) > +pid namespace. > +.TP > .B EINVAL > The caller attempted to join the user namespace > in which it is already a member. > diff --git a/man7/pid_namespaces.7 b/man7/pid_namespaces.7 > index 8582da3..89c606b 100644 > --- a/man7/pid_namespaces.7 > +++ b/man7/pid_namespaces.7 > @@ -188,6 +188,16 @@ PID namespace from the caller of > Calls to > .BR getppid (2) > for such processes return 0. > + > +While processes may freely descend into children PID namespaces > +(e.g. using > +.BR setns (2) > +with > +.BR CLONE_NEWPID ), > +they may not move in the other direction. > +That is to say, processes may not enter any ancestor namespaces > +(parent, grandparent, etc.). > +Changing PID namespaces is a one way operation. > .\" > .\" ============================================================ > .\" > -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/ -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
