Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754398AbYKZDqi (ORCPT ); Tue, 25 Nov 2008 22:46:38 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753159AbYKZDq3 (ORCPT ); Tue, 25 Nov 2008 22:46:29 -0500 Received: from e3.ny.us.ibm.com ([32.97.182.143]:52014 "EHLO e3.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751956AbYKZDq3 (ORCPT ); Tue, 25 Nov 2008 22:46:29 -0500 Date: Tue, 25 Nov 2008 19:46:11 -0800 From: Sukadev Bhattiprolu To: oleg@redhat.com, ebiederm@xmission.com, roland@redhat.com Cc: daniel@hozac.com, xemul@openvz.org, containers@lists.osdl.org, linux-kernel@vger.kernel.org, sukadev@us.ibm.com Subject: [RFC][PATCH 3/5] Determine if sender is from ancestor ns Message-ID: <20081126034611.GC23238@us.ibm.com> References: <20081126034242.GA23120@us.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20081126034242.GA23120@us.ibm.com> X-Operating-System: Linux 2.0.32 on an i486 User-Agent: Mutt/1.5.15+20070412 (2007-04-11) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3534 Lines: 111 >From 95ae5f7dfaa77158b07d2cbdc8e5df0a81c93194 Mon Sep 17 00:00:00 2001 From: Sukadev Bhattiprolu Date: Tue, 18 Nov 2008 16:55:06 -0800 Subject: [PATCH 3/5] Determine if sender is from ancestor ns To implement container-init semantics, send_signal() must compute the pid namespace of the sender, but since signals may originate in workqueues/ interrupt handlers, computing the namespace of sender is not always possible/safe. Define a flag, SIG_FROM_USER and set this flag when a signal originates from user-space (i.e in kill(), tkill(), rt_sigqueueinfo()). When this flag is set, send_signal() can safely compute the pid namespace of the sender. Signed-off-by: Sukadev Bhattiprolu --- kernel/signal.c | 35 ++++++++++++++++++++++++++++++++--- 1 files changed, 32 insertions(+), 3 deletions(-) diff --git a/kernel/signal.c b/kernel/signal.c index d8d20d6..45aebf0 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -793,14 +793,42 @@ static inline int legacy_queue(struct sigpending *signals, int sig) return (sig < SIGRTMIN) && sigismember(&signals->signal, sig); } +/* + * Return 1 if this signal originated directly from a user process (i.e via + * kill(), tkill(), sigqueue()) that is in an ancestor pid namespace of @t. + * Return 0 otherwise. + */ +#ifdef CONFIG_PID_NS +#define SIG_FROM_USER INT_MIN /* MSB */ +static inline int siginfo_from_ancestor_ns(struct task_struct *t, + siginfo_t *info) +{ + if (!is_si_special(info) && (info->si_signo & SIG_FROM_USER)) { + /* if t can't see us we are from parent ns */ + if (task_pid_nr_ns(current, task_active_pid_ns(t)) <= 0) + return 1; + } + return 0; +} +#else +static inline int siginfo_from_ancestor_ns(struct task_struct *t, + siginfo_t *info) +{ + return 0; +} +#endif + static int send_signal(int sig, struct siginfo *info, struct task_struct *t, int group) { struct sigpending *pending; struct sigqueue *q; + int from_ancestor_ns; trace_sched_signal_send(sig, t); + from_ancestor_ns = siginfo_from_ancestor_ns(t, info); + assert_spin_locked(&t->sighand->siglock); if (!prepare_signal(sig, t)) return 0; @@ -850,6 +878,7 @@ static int send_signal(int sig, struct siginfo *info, struct task_struct *t, break; default: copy_siginfo(&q->info, info); + q->info.si_signo &= ~SIG_FROM_USER; break; } } else if (!is_si_special(info)) { @@ -2202,7 +2231,7 @@ sys_kill(pid_t pid, int sig) { struct siginfo info; - info.si_signo = sig; + info.si_signo = sig | SIG_FROM_USER; info.si_errno = 0; info.si_code = SI_USER; info.si_pid = task_tgid_vnr(current); @@ -2219,7 +2248,7 @@ static int do_tkill(pid_t tgid, pid_t pid, int sig) unsigned long flags; error = -ESRCH; - info.si_signo = sig; + info.si_signo = sig | SIG_FROM_USER; info.si_errno = 0; info.si_code = SI_TKILL; info.si_pid = task_tgid_vnr(current); @@ -2291,7 +2320,7 @@ sys_rt_sigqueueinfo(pid_t pid, int sig, siginfo_t __user *uinfo) Nor can they impersonate a kill(), which adds source info. */ if (info.si_code >= 0) return -EPERM; - info.si_signo = sig; + info.si_signo = sig | SIG_FROM_USER; /* POSIX.1b doesn't mention process groups. */ return kill_proc_info(sig, &info, pid); -- 1.5.2.5 -- 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/