From: Mike Frysinger <vapier@gentoo.org>
To: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: linux-man@vger.kernel.org
Subject: [PATCH] setns.2: fix CLONE_NEWNS restriction info
Date: Thu, 19 Sep 2019 01:43:42 -0400 [thread overview]
Message-ID: <20190919054342.5405-1-vapier@gentoo.org> (raw)
Threads are allowed to switch mount namespaces if the filesystem
details aren't being shared. That's the purpose of the check in
the kernel quoted by the comment:
if (fs->users != 1)
return -EINVAL;
It's been this way since the code was originally merged in v3.8.
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
---
man2/setns.2 | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/man2/setns.2 b/man2/setns.2
index 18e80202326a..5985c099b464 100644
--- a/man2/setns.2
+++ b/man2/setns.2
@@ -131,8 +131,12 @@ capabilities in its own user namespace and
.BR CAP_SYS_ADMIN
in the user namespace that owns the target mount namespace.
.IP
-A process may not be reassociated with a new mount namespace if it is
-multithreaded.
+A process can't join a new mount namespace if it is sharing
+filesystem-related attributes
+(the attributes whose sharing is controlled by the
+.BR clone (2)
+.B CLONE_FS
+flag) with another process.
.\" Above check is in fs/namespace.c:mntns_install() [3.8 source]
.IP
See
--
2.23.0
next reply other threads:[~2019-09-19 5:43 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-19 5:43 Mike Frysinger [this message]
2019-09-19 6:38 ` [PATCH] setns.2: fix CLONE_NEWNS restriction info Michael Kerrisk (man-pages)
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