This is inline with POSIX terminology. See also the earlier
commit a00b7454b8 (in 2012)
which fixed most of these cases.
Reported-by: Jakub Wilk <jwilk@jwilk.net>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
The left-most pid namespace in a given procfs' `NStgid` does not
change based on the pid namespace of the reading process. Rather,
each procfs has an associated outer-most namespace, which gets
set when the procfs is mounted:
```
static struct dentry *proc_mount(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data)
{
struct pid_namespace *ns;
if (flags & MS_KERNMOUNT) {
ns = data;
data = NULL;
} else {
ns = task_active_pid_ns(current);
}
return mount_ns(fs_type, flags, data, ns, ns->user_ns, proc_fill_super);
}
```
i.e. either the root namespace for kernel mounts or the namespace
of the mounting process. This ns then gets saved in the fs' super
block and is the basis for most operations. It is this ns that the
left-most value of `NStgid` is relative to, not the reading process.
Reported-by: Robert O'Callahan <robert@ocallahan.org>
Signed-off-by: Keno Fischer <keno@juliacomputing.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
LC_GLOBAL_HANDLE is not defined anywhere, the doc meant LC_GLOBAL_LOCALE
instead.
Reported-by: Solal Pirelli <solal.pirelli@gmail.com>
Signed-off-by: Antonio Ospite <ao2@ao2.it>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
The EINVAL errors that can occur for clone(2) when it is called
with various CLONE_NEW* flags and the kernel was not configured
with support for the corresponding namespace can also occur for
unshare(2). (As far as I can see, these errors don't occur for
either clone(2) or unshare(2) when it comes to CLONE_NEWNS and
CLONE_NEWCGROUP.)
Reported-by: Shawn Landden <shawn@git.icu>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Note that EINVAL can occur with CLONE_NEWUSER if the kernel was
not configured with CONFIG_USER_NS.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Some other socket options that are applicable for TCP and UDP sockets
are documented in socket(7), so help the reader by pointing them at
that page.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
When it fails, inet_aton() does not set errno, so using
perror() is not appropriate.
Reported-by: Antonio Chirizzi <antonio.chirizzi@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Explain how to determine the top-most mount at a particular
location by inspecting /proc/PID/mountinfo.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Thanks to a tip from Keith Packard:
https://keithp.com/blogs/fd-passing/
(Also verified by experiment.)
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
When sending ancillary data, at least one byte of real data should
also be sent. This is strictly necessary for stream sockets
(verified by experiment). It is not required for datagram sockets
on Linux (verified by experiment), but portable applications
should do so.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
If the ancillary data buffer for receiving SCM_RIGHTS file
descriptors is too small, then the excess file descriptors are
automatically closed in the receiving process. Verified by
experiment.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Michael Kerrisk