Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933116AbaFQS10 (ORCPT ); Tue, 17 Jun 2014 14:27:26 -0400 Received: from mail-we0-f171.google.com ([74.125.82.171]:41342 "EHLO mail-we0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752971AbaFQS1Y (ORCPT ); Tue, 17 Jun 2014 14:27:24 -0400 MIME-Version: 1.0 In-Reply-To: <1403000496-10094-1-git-send-email-chenhanxiao@cn.fujitsu.com> References: <1403000496-10094-1-git-send-email-chenhanxiao@cn.fujitsu.com> From: Michael Kerrisk Date: Tue, 17 Jun 2014 20:27:03 +0200 X-Google-Sender-Auth: MhuGvVyGRm7cb5leJYrq9NoVB_w Message-ID: Subject: Re: [PATCH] ns: introduce getnspid syscall To: Chen Hanxiao Cc: containers , Linux Kernel , Richard Weinberger , Serge Hallyn , Oleg Nesterov , David Howells , "Eric W. Biederman" , Andrew Morton , Al Viro , Linux API , Michael Kerrisk-manpages Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Chen Hanxiao On Tue, Jun 17, 2014 at 12:21 PM, Chen Hanxiao wrote: > We need a direct method of getting the pid inside containers. > If some issues occurred inside container guest, host user > could not know which process is in trouble just by guest pid: > the users of container guest only knew the pid inside containers. > This will bring obstacle for trouble shooting. > > int getnspid(pid_t pid, int fd1, int fd2, int pidtype); Please CC linux-api@vger.kernel.org on all patches that change the API that the kernel presents to user space. See https://www.kernel.org/doc/man-pages/linux-api-ml.html Thanks, Michael > pid: the pid number need to be translated. > > fd: a file descriptor referring to one of > the namespace entries in a /proc/[pid]/ns/pid. > fd1 for destination ns(ns1), where the pid came from. > fd2 for reference ns(ns2), while fd2 = -2 means for current ns. > > pidtype: 0 PIDTYPE_PID; 1 PIDTYPE_PGID; 2 PIDTYPE_SID. > > return value: > >0: translated pid in ns1(fd1) seen from ns2(fd2). > <0: on failure. > > Signed-off-by: Chen Hanxiao > --- > arch/x86/syscalls/syscall_32.tbl | 1 + > arch/x86/syscalls/syscall_64.tbl | 1 + > include/linux/syscalls.h | 1 + > kernel/nsproxy.c | 60 ++++++++++++++++++++++++++++++++++++++++ > 4 files changed, 63 insertions(+) > > diff --git a/arch/x86/syscalls/syscall_32.tbl b/arch/x86/syscalls/syscall_32.tbl > index d6b8679..9de0b32 100644 > --- a/arch/x86/syscalls/syscall_32.tbl > +++ b/arch/x86/syscalls/syscall_32.tbl > @@ -360,3 +360,4 @@ > 351 i386 sched_setattr sys_sched_setattr > 352 i386 sched_getattr sys_sched_getattr > 353 i386 renameat2 sys_renameat2 > +354 i386 getnspid sys_getnspid > diff --git a/arch/x86/syscalls/syscall_64.tbl b/arch/x86/syscalls/syscall_64.tbl > index ec255a1..1630a8a 100644 > --- a/arch/x86/syscalls/syscall_64.tbl > +++ b/arch/x86/syscalls/syscall_64.tbl > @@ -323,6 +323,7 @@ > 314 common sched_setattr sys_sched_setattr > 315 common sched_getattr sys_sched_getattr > 316 common renameat2 sys_renameat2 > +317 common getnspid sys_getnspid > > # > # x32-specific system call numbers start at 512 to avoid cache impact > diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h > index b0881a0..271c7b1 100644 > --- a/include/linux/syscalls.h > +++ b/include/linux/syscalls.h > @@ -866,4 +866,5 @@ asmlinkage long sys_process_vm_writev(pid_t pid, > asmlinkage long sys_kcmp(pid_t pid1, pid_t pid2, int type, > unsigned long idx1, unsigned long idx2); > asmlinkage long sys_finit_module(int fd, const char __user *uargs, int flags); > +asmlinkage long sys_getpidns(pid_t pid, int fd1, int fd2, int pidtype); > #endif > diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c > index 8e78110..3eda90a 100644 > --- a/kernel/nsproxy.c > +++ b/kernel/nsproxy.c > @@ -261,6 +261,66 @@ out: > return err; > } > > +SYSCALL_DEFINE4(getnspid, pid_t, pid, int, fd1, int, fd2, int, pidtype) > +{ > + struct file *file1 = NULL, *file2 = NULL; > + struct task_struct *task; > + struct pid_namespace *ns1, *ns2; > + struct proc_ns *ei; > + int ret = -1; > + > + if (pidtype >= PIDTYPE_MAX) > + return -EINVAL; > + > + file1 = proc_ns_fget(fd1); > + if (IS_ERR(file1)) > + return PTR_ERR(file1); > + ei = get_proc_ns(file_inode(file1)); > + ns1 = (struct pid_namespace *)ei->ns; > + > + /* fd == -2 for current pid ns */ > + if (fd2 == -2) { > + ns2 = task_active_pid_ns(current); > + } else { > + file2 = proc_ns_fget(fd2); > + if (IS_ERR(file2)) { > + fput(file1); > + return PTR_ERR(file2); > + } > + ei = get_proc_ns(file_inode(file2)); > + ns2 = (struct pid_namespace *)ei->ns; > + } > + > + rcu_read_lock(); > + task = find_task_by_pid_ns(pid, ns1); > + rcu_read_unlock(); > + if (!task) { > + ret = -ESRCH; > + goto out; > + } > + > + switch (pidtype) { > + case PIDTYPE_PID: > + ret = task_pid_nr_ns(task, ns2); > + break; > + case PIDTYPE_PGID: > + ret = task_pgrp_nr_ns(task, ns2); > + break; > + case PIDTYPE_SID: > + ret = task_session_nr_ns(task, ns2); > + break; > + default: > + ret = -EINVAL; > + } > + ret = (ret == 0) ? -ESRCH : ret; > + > +out: > + fput(file1); > + if (file2) > + fput(file2); > + return ret; > +} > + > int __init nsproxy_cache_init(void) > { > nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC); > -- > 1.9.0 > > _______________________________________________ > Containers mailing list > Containers@lists.linux-foundation.org > https://lists.linuxfoundation.org/mailman/listinfo/containers -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Author of "The Linux Programming Interface", http://blog.man7.org/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/