From: Kirill Tkhai <ktkhai@xxxxxxxxxxxxx> Subject: ns: allow ns_entries to have custom symlink content 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. Link: http://lkml.kernel.org/r/149201120318.6007.7362655181033883000.stgit@localhost.localdomain Signed-off-by: Kirill Tkhai <ktkhai@xxxxxxxxxxxxx> Reviewed-by: Cyrill Gorcunov <gorcunov@xxxxxxxxxx> Acked-by: Andrei Vagin <avagin@xxxxxxxxxxxxx> Cc: Andreas Gruenbacher <agruenba@xxxxxxxxxx> Cc: Kees Cook <keescook@xxxxxxxxxxxx> Cc: Michael Kerrisk <mtk.manpages@xxxxxxxxxxxxxx> Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx> Cc: Oleg Nesterov <oleg@xxxxxxxxxx> Cc: Paul Moore <paul@xxxxxxxxxxxxxx> Cc: Eric Biederman <ebiederm@xxxxxxxxxxxx> Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Serge Hallyn <serge@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/nsfs.c | 4 +++- include/linux/proc_ns.h | 1 + 2 files changed, 4 insertions(+), 1 deletion(-) diff -puN fs/nsfs.c~ns-allow-ns_entries-to-have-custom-symlink-content fs/nsfs.c --- a/fs/nsfs.c~ns-allow-ns_entries-to-have-custom-symlink-content +++ a/fs/nsfs.c @@ -196,9 +196,11 @@ int ns_get_name(char *buf, size_t size, { 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 -puN include/linux/proc_ns.h~ns-allow-ns_entries-to-have-custom-symlink-content include/linux/proc_ns.h --- a/include/linux/proc_ns.h~ns-allow-ns_entries-to-have-custom-symlink-content +++ a/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); _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
