Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754265AbYL0MUs (ORCPT ); Sat, 27 Dec 2008 07:20:48 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753429AbYL0MUj (ORCPT ); Sat, 27 Dec 2008 07:20:39 -0500 Received: from zelda.netsplit.com ([87.194.19.211]:35233 "EHLO zelda.netsplit.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753213AbYL0MUi (ORCPT ); Sat, 27 Dec 2008 07:20:38 -0500 X-Greylist: delayed 2152 seconds by postgrey-1.27 at vger.kernel.org; Sat, 27 Dec 2008 07:20:37 EST Date: Sat, 27 Dec 2008 11:44:53 +0000 From: Scott James Remnant To: lkml Subject: [RFC][PATCH] Notify init when processes are reparented to it Message-ID: <20081227114452.GA2919@zelda.netsplit.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1230378128.7026.50.camel@quest> User-Agent: Mutt/1.5.17+20080114 (2008-01-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6605 Lines: 190 Allow the init daemon to be notified by signal when processes are reparented to it. The signal has the same form as SIGCHLD except that the si_status field contains the original parent proecss id. Notification is enabled/disabled by prctl(). Signed-off-by: Scott James Remnant --- fs/exec.c | 2 ++ include/linux/prctl.h | 4 ++++ include/linux/sched.h | 2 ++ kernel/exit.c | 3 +++ kernel/signal.c | 37 +++++++++++++++++++++++++++++++++++++ kernel/sys.c | 10 ++++++++++ security/commoncap.c | 1 + security/selinux/hooks.c | 4 +++- 8 files changed, 62 insertions(+), 1 deletions(-) diff --git a/fs/exec.c b/fs/exec.c index c5f1a92..07a8782 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1011,6 +1011,7 @@ int flush_old_exec(struct linux_binprm * bprm) suid_keys(current); set_dumpable(current->mm, suid_dumpable); current->pdeath_signal = 0; + current->adopt_signal = 0; } else if (file_permission(bprm->file, MAY_READ) || (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) { suid_keys(current); @@ -1099,6 +1100,7 @@ void compute_creds(struct linux_binprm *bprm) if (bprm->e_uid != current->uid) { suid_keys(current); current->pdeath_signal = 0; + current->adopt_signal = 0; } exec_keys(current); diff --git a/include/linux/prctl.h b/include/linux/prctl.h index 48d887e..1fa1b75 100644 --- a/include/linux/prctl.h +++ b/include/linux/prctl.h @@ -85,4 +85,8 @@ #define PR_SET_TIMERSLACK 29 #define PR_GET_TIMERSLACK 30 +/* Set/get notification of adoption by signal */ +#define PR_SET_ADOPTSIG 31 /* Second arg is a signal */ +#define PR_GET_ADOPTSIG 32 /* Second arg is a ptr to return the signal */ + #endif /* _LINUX_PRCTL_H */ diff --git a/include/linux/sched.h b/include/linux/sched.h index 55e30d1..bcd2af3 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1133,6 +1133,7 @@ struct task_struct { int exit_state; int exit_code, exit_signal; int pdeath_signal; /* The signal sent when the parent dies */ + int adopt_signal; /* The signal sent when a process is reparented */ /* ??? */ unsigned int personality; unsigned did_exec:1; @@ -1829,6 +1830,7 @@ extern int kill_pgrp(struct pid *pid, int sig, int priv); extern int kill_pid(struct pid *pid, int sig, int priv); extern int kill_proc_info(int, struct siginfo *, pid_t); extern int do_notify_parent(struct task_struct *, int); +extern void do_notify_parent_adopted(struct task_struct *, struct task_struct *); extern void force_sig(int, struct task_struct *); extern void force_sig_specific(int, struct task_struct *); extern int send_sig(int, struct task_struct *, int); diff --git a/kernel/exit.c b/kernel/exit.c index 2d8be7e..813a232 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -813,6 +813,9 @@ static void reparent_thread(struct task_struct *p, struct task_struct *father) /* We already hold the tasklist_lock here. */ group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p); + if (p->real_parent->adopt_signal) + do_notify_parent_adopted(p, father); + list_move_tail(&p->sibling, &p->real_parent->children); /* If this is a threaded reparent there is no need to diff --git a/kernel/signal.c b/kernel/signal.c index 4530fc6..40228e2 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -1474,6 +1474,43 @@ static void do_notify_parent_cldstop(struct task_struct *tsk, int why) spin_unlock_irqrestore(&sighand->siglock, flags); } +/* Let init know that it has adopted a new child */ +void do_notify_parent_adopted(struct task_struct *tsk, struct task_struct *father) +{ + struct siginfo info; + unsigned long flags; + struct task_struct *reaper; + struct sighand_struct *sighand; + int ret; + + reaper = tsk->real_parent; + + memset (&info, 0, sizeof info); + info.si_signo = reaper->adopt_signal; + /* + * set code to the same range as SIGCHLD so the right bits of + * siginfo_t get copied, to userspace this will appear as si_code=0 + */ + info.si_code = __SI_CHLD; + /* + * see comment in do_notify_parent() about the following 4 lines + */ + rcu_read_lock(); + info.si_pid = task_pid_nr_ns(tsk, reaper->nsproxy->pid_ns); + info.si_status = task_pid_nr_ns(father, reaper->nsproxy->pid_ns); + rcu_read_unlock(); + + info.si_uid = tsk->uid; + + info.si_utime = cputime_to_clock_t(tsk->utime); + info.si_stime = cputime_to_clock_t(tsk->stime); + + sighand = reaper->sighand; + spin_lock_irqsave(&sighand->siglock, flags); + __group_send_sig_info(reaper->adopt_signal, &info, reaper); + spin_unlock_irqrestore(&sighand->siglock, flags); +} + static inline int may_ptrace_stop(void) { if (!likely(current->ptrace & PT_PTRACED)) diff --git a/kernel/sys.c b/kernel/sys.c index 31deba8..1720053 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -1726,6 +1726,16 @@ asmlinkage long sys_prctl(int option, unsigned long arg2, unsigned long arg3, else current->timer_slack_ns = arg2; break; + case PR_SET_ADOPTSIG: + if (!valid_signal(arg2)) { + error = -EINVAL; + break; + } + current->adopt_signal = arg2; + break; + case PR_GET_ADOPTSIG: + error = put_user(current->adopt_signal, (int __user *)arg2); + break; default: error = -EINVAL; break; diff --git a/security/commoncap.c b/security/commoncap.c index 6cbec11..a2da3ab 100644 --- a/security/commoncap.c +++ b/security/commoncap.c @@ -365,6 +365,7 @@ void cap_bprm_apply_creds (struct linux_binprm *bprm, int unsafe) current->cap_permitted)) { set_dumpable(current->mm, suid_dumpable); current->pdeath_signal = 0; + current->adopt_signal = 0; if (unsafe & ~LSM_UNSAFE_PTRACE_CAP) { if (!capable(CAP_SETUID)) { diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 75777cb..8f089c8 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -2280,8 +2280,10 @@ static void selinux_bprm_post_apply_creds(struct linux_binprm *bprm) spin_unlock_irq(¤t->sighand->siglock); } - /* Always clear parent death signal on SID transitions. */ + /* Always clear parent death signal and adoption notification + * on SID transitions. */ current->pdeath_signal = 0; + current->adopt_signal = 0; /* Check whether the new SID can inherit resource limits from the old SID. If not, reset all soft limits to -- 1.6.0.5 -- 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/