"Michael Kerrisk (man-pages)" <mtk.manpages@xxxxxxxxx> writes: > On 04/05/2018 09:02 AM, Konstantin Khlebnikov wrote: >> On 05.04.2018 01:29, Eric W. Biederman wrote: >>> Nagarathnam Muthusamy <nagarathnam.muthusamy@xxxxxxxxxx> writes: >>> >>>> On 04/04/2018 12:11 PM, Konstantin Khlebnikov wrote: >>>>> Each process have different pids, one for each pid namespace it belongs. >>>>> When interaction happens within single pid-ns translation isn't required. >>>>> More complicated scenarios needs special handling. >>>>> >>>>> For example: >>>>> - reading pid-files or logs written inside container with pid namespace >>>>> - attaching with ptrace to tasks from different pid namespace >>>>> - passing pids across pid namespaces in any kind of API >>>>> >>>>> Currently there are several interfaces that could be used here: >>>>> >>>>> Pid namespaces are identified by inode number of /proc/[pid]/ns/pid. >>> >>> Using the inode number in interfaces is not an option. Especially not >>> withou referencing the device number for the filesystem as well. >> >> This is supposed to be single-instance fs, >> not part of proc but referenced but its magic "symlinks". >> >> Device numbers are not mentioned in "man namespaces". > > Thanks for the heads-up! > > That was a bug in the man-page. ioctl_ns(2) already says the right thing. > Now I patches namespaces(7), as below. Acked-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> For the changes to namespaces.7. I suspect you have already applied them by now, but if not. Eric > Cheers, > > Michael > > diff --git a/man7/namespaces.7 b/man7/namespaces.7 > index 725ebaff6..3c155de7e 100644 > --- a/man7/namespaces.7 > +++ b/man7/namespaces.7 > @@ -154,11 +154,14 @@ In Linux 3.7 and earlier, these files were visible as hard links. > Since Linux 3.8, > .\" commit bf056bfa80596a5d14b26b17276a56a0dcb080e5 > they appear as symbolic links. > -If two processes are in the same namespace, then the inode numbers of their > +If two processes are in the same namespace, > +then the device IDs and inode numbers of their > .IR /proc/[pid]/ns/xxx > symbolic links will be the same; an application can check this using the > +.I stat.st_dev > +and > .I stat.st_ino > -field returned by > +fields returned by > .BR stat (2). > The content of this symbolic link is a string containing > the namespace type and inode number as in the following example: -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
