From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kirill Tkhai Subject: [PATCH v2 1/2] ns: Allow ns_entries to have custom symlink content Date: Wed, 12 Apr 2017 18:33:47 +0300 Message-ID: <149201120318.6007.7362655181033883000.stgit@localhost.localdomain> References: <149201102204.6007.8628824763325355297.stgit@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <149201102204.6007.8628824763325355297.stgit-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@public.gmane.org> Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: serge-A9i7LUbDfNHQT0dZR+AlfA@public.gmane.org, ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org, agruenba-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, oleg-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, paul-r2n+y4ga6xFZroRs9YW3xA@public.gmane.org, ktkhai-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org, viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org, avagin-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org, linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, luto-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org, gorcunov-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org, mingo-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org List-Id: linux-api@vger.kernel.org Patch series "Expose task pid_ns_for_children to userspace". pid_ns_for_children set by a task is known only to the task itself, and it's impossible to identify it from outside. It's a big problem for checkpoint/restore software like CRIU, because it can't correctly handle tasks, that do setns(CLONE_NEWPID) in proccess of their work. If they have a custom pid_ns_for_children before dump, they must have the same ns after restore. Otherwise, restored task bumped into enviroment it does not expect. This patchset solves the problem. It exposes pid_ns_for_children to ns directory in standard way with the name "pid_for_children": ~# ls /proc/5531/ns -l | grep pid lrwxrwxrwx 1 root root 0 Jan 14 16:38 pid -> pid:[4026531836] lrwxrwxrwx 1 root root 0 Jan 14 16:38 pid_for_children -> pid:[4026532286] This patch (of 2): Make possible to have link content prefix yyy different from the link name xxx: $ readlink /proc/[pid]/ns/xxx yyy:[4026531838] This will be used in next patch. Signed-off-by: Kirill Tkhai Reviewed-by: Cyrill Gorcunov Acked-by: Andrei Vagin --- fs/nsfs.c | 4 +++- include/linux/proc_ns.h | 1 + 2 files changed, 4 insertions(+), 1 deletion(-) diff --git a/fs/nsfs.c b/fs/nsfs.c index 1656843e87d2..495f12b83a7b 100644 --- a/fs/nsfs.c +++ b/fs/nsfs.c @@ -195,9 +195,11 @@ int ns_get_name(char *buf, size_t size, struct task_struct *task, { struct ns_common *ns; int res = -ENOENT; + const char *name; ns = ns_ops->get(task); if (ns) { - res = snprintf(buf, size, "%s:[%u]", ns_ops->name, ns->inum); + name = ns_ops->real_ns_name ? : ns_ops->name; + res = snprintf(buf, size, "%s:[%u]", name, ns->inum); ns_ops->put(ns); } return res; diff --git a/include/linux/proc_ns.h b/include/linux/proc_ns.h index 12cb8bd81d2d..88dba3b53375 100644 --- a/include/linux/proc_ns.h +++ b/include/linux/proc_ns.h @@ -14,6 +14,7 @@ struct inode; struct proc_ns_operations { const char *name; + const char *real_ns_name; int type; struct ns_common *(*get)(struct task_struct *task); void (*put)(struct ns_common *ns);