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Revision 1.90, Tue May 1 16:37:23 2018 UTC (5 years, 10 months ago) by kamil
Branch: MAIN
CVS Tags: pgoyette-compat-0502
Changes since 1.89: +3 -1 lines

Implement PTRACE_VFORK

Add support for tracing vfork(2) events in the context of ptrace(2).

This API covers other frontends to fork1(9) like posix_spawn(2) or clone(2),
if they cause parent to wait for exec(2) or exit(2) of the child.

Changes:
 - Add new argument to sigswitch() determining whether we need to acquire
   the proc_lock or whether it's already held.
 - Refactor fork1(9) for fork(2) and vfork(2)-like events.
   Call sigswitch() from fork(1) for forking or vforking parent, instead of
   emitting kpsignal(9). We need to emit the signal and suspend the parent,
   returning to user and relock proc_lock.
 - Add missing prototype for proc_stop_done() in kern_sig.c.
 - Make sigswitch a public function accessible from other kernel code
   including <sys/signalvar.h>.
 - Remove an entry about unimplemented PTRACE_VFORK in the ptrace(2) man page.
 - Permin PTRACE_VFORK in the ptrace(2) frontend for userland.
 - Remove expected failure for unimplemented PTRACE_VFORK tests in the ATF
   ptrace(2) test-suite.
 - Relax signal routing constraints under a debugger for a vfork(2)ed child.
   This intended to protect from signaling a parent of a vfork(2)ed child that
   called PT_TRACE_ME, but wrongly misrouted other signals in vfork(2)
   use-cases.

Add XXX comments about still existing problems and future enhancements:
 - correct vfork(2) + PT_TRACE_ME handling.
 - fork1(2) handling of scenarios when a process is collected in valid but
   rare cases.

All ATF ptrace(2) fork[1-8] and vfork[1-8] tests pass.

Fix PR kern/51630 by Kamil Rytarowski (myself).

Sponsored by <The NetBSD Foundation>

/*	$NetBSD: signalvar.h,v 1.90 2018/05/01 16:37:23 kamil Exp $	*/

/*
 * Copyright (c) 1991, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)signalvar.h	8.6 (Berkeley) 2/19/95
 */

#ifndef	_SYS_SIGNALVAR_H_
#define	_SYS_SIGNALVAR_H_

#include <sys/siginfo.h>
#include <sys/queue.h>
#include <sys/mutex.h>
#include <sys/stdbool.h>

/*
 * Kernel signal definitions and data structures,
 * not exported to user programs.
 */

/*
 * Queue of signals.
 */
typedef TAILQ_HEAD(ksiginfoq, ksiginfo) ksiginfoq_t;

/*
 * Process signal actions, possibly shared between processes.
 */
struct sigacts {
	struct sigact_sigdesc {
		struct sigaction sd_sigact;
		const void	*sd_tramp;
		int		sd_vers;
	} sa_sigdesc[NSIG];		/* disposition of signals */

	int		sa_refcnt;	/* reference count */
	kmutex_t	sa_mutex;	/* lock on sa_refcnt */
};

/*
 * Pending signals, per LWP and per process.
 */
typedef struct sigpend {
	ksiginfoq_t	sp_info;
	sigset_t	sp_set;
} sigpend_t;

/*
 * Process signal state.
 */
struct sigctx {
	struct _ksiginfo ps_info;	/* for core dump/debugger XXX */
	int		 ps_lwp;	/* for core dump/debugger XXX */
	bool		 ps_faked;	/* for core dump/debugger XXX */
	void		*ps_sigcode;	/* address of signal trampoline */
	sigset_t	 ps_sigignore;	/* Signals being ignored. */
	sigset_t	 ps_sigcatch;	/* Signals being caught by user. */
};

/* additional signal action values, used only temporarily/internally */
#define	SIG_CATCH	(void (*)(int))2

/*
 * get signal action for process and signal; currently only for current process
 */
#define SIGACTION(p, sig)	(p->p_sigacts->sa_sigdesc[(sig)].sd_sigact)
#define	SIGACTION_PS(ps, sig)	(ps->sa_sigdesc[(sig)].sd_sigact)

/*
 * Signal properties and actions.
 * The array below categorizes the signals and their default actions
 * according to the following properties:
 */
#define	SA_KILL		0x0001		/* terminates process by default */
#define	SA_CORE		0x0002		/* ditto and coredumps */
#define	SA_STOP		0x0004		/* suspend process */
#define	SA_TTYSTOP	0x0008		/* ditto, from tty */
#define	SA_IGNORE	0x0010		/* ignore by default */
#define	SA_CONT		0x0020		/* continue if suspended */
#define	SA_CANTMASK	0x0040		/* non-maskable, catchable */
#define	SA_NORESET	0x0080		/* not reset when caught */
#define	SA_TOLWP	0x0100		/* to LWP that generated, if local */
#define	SA_TOALL	0x0200		/* always to all LWPs */

#ifdef _KERNEL

#include <sys/systm.h>			/* for copyin_t/copyout_t */

extern sigset_t contsigmask, sigcantmask;

struct vnode;
struct coredump_iostate;

/*
 * Machine-independent functions:
 */
int	coredump_netbsd(struct lwp *, struct coredump_iostate *);
void	execsigs(struct proc *);
int	issignal(struct lwp *);
void	pgsignal(struct pgrp *, int, int);
void	kpgsignal(struct pgrp *, struct ksiginfo *, void *, int);
void	postsig(int);
void	psignal(struct proc *, int);
void	kpsignal(struct proc *, struct ksiginfo *, void *);
void	child_psignal(struct proc *, int);
void	siginit(struct proc *);
void	trapsignal(struct lwp *, struct ksiginfo *);
void	sigexit(struct lwp *, int) __dead;
void	killproc(struct proc *, const char *);
void	setsigvec(struct proc *, int, struct sigaction *);
int	killpg1(struct lwp *, struct ksiginfo *, int, int);
void	proc_unstop(struct proc *p);
void	sigswitch(int, int, bool);


int	sigaction1(struct lwp *, int, const struct sigaction *,
	    struct sigaction *, const void *, int);
int	sigprocmask1(struct lwp *, int, const sigset_t *, sigset_t *);
void	sigpending1(struct lwp *, sigset_t *);
void	sigsuspendsetup(struct lwp *, const sigset_t *);
void	sigsuspendteardown(struct lwp *);
int	sigsuspend1(struct lwp *, const sigset_t *);
int	sigaltstack1(struct lwp *, const struct sigaltstack *,
	    struct sigaltstack *);
int	sigismasked(struct lwp *, int);

int	sigget(sigpend_t *, ksiginfo_t *, int, const sigset_t *);
void	sigclear(sigpend_t *, const sigset_t *, ksiginfoq_t *);
void	sigclearall(struct proc *, const sigset_t *, ksiginfoq_t *);

int	kpsignal2(struct proc *, ksiginfo_t *);

void	signal_init(void);

struct sigacts	*sigactsinit(struct proc *, int);
void	sigactsunshare(struct proc *);
void	sigactsfree(struct sigacts *);

void	kpsendsig(struct lwp *, const struct ksiginfo *, const sigset_t *);
void	sendsig_reset(struct lwp *, int);
void	sendsig(const struct ksiginfo *, const sigset_t *);

ksiginfo_t	*ksiginfo_alloc(struct proc *, ksiginfo_t *, int);
void	ksiginfo_free(ksiginfo_t *);
void	ksiginfo_queue_drain0(ksiginfoq_t *);

struct sys_____sigtimedwait50_args;
int	sigtimedwait1(struct lwp *, const struct sys_____sigtimedwait50_args *,
    register_t *, copyin_t, copyout_t, copyin_t, copyout_t);

void	signotify(struct lwp *);
int	sigispending(struct lwp *, int);

/*
 * Machine-dependent functions:
 */
void	sendsig_sigcontext(const struct ksiginfo *, const sigset_t *);
void	sendsig_siginfo(const struct ksiginfo *, const sigset_t *);

extern	struct pool ksiginfo_pool;

/*
 * Modularity / compatibility.
 */
extern void	(*sendsig_sigcontext_vec)(const struct ksiginfo *,
					  const sigset_t *);
extern int	(*coredump_vec)(struct lwp *, const char *);

/*
 * firstsig:
 *
 * 	Return the first signal in a signal set.
 */
static __inline int
firstsig(const sigset_t *ss)
{
	int sig;

	sig = ffs(ss->__bits[0]);
	if (sig != 0)
		return (sig);
#if NSIG > 33
	sig = ffs(ss->__bits[1]);
	if (sig != 0)
		return (sig + 32);
#endif
#if NSIG > 65
	sig = ffs(ss->__bits[2]);
	if (sig != 0)
		return (sig + 64);
#endif
#if NSIG > 97
	sig = ffs(ss->__bits[3]);
	if (sig != 0)
		return (sig + 96);
#endif
	return (0);
}

static __inline void
ksiginfo_queue_init(ksiginfoq_t *kq)
{
	TAILQ_INIT(kq);
}

static __inline void
ksiginfo_queue_drain(ksiginfoq_t *kq)
{
	if (!TAILQ_EMPTY(kq))
		ksiginfo_queue_drain0(kq);
}

#endif	/* _KERNEL */

#ifdef	_KERNEL
#ifdef	SIGPROP
const int sigprop[NSIG] = {
	0,					/* 0 unused */
	SA_KILL,				/* 1 SIGHUP */
	SA_KILL,				/* 2 SIGINT */
	SA_KILL|SA_CORE,			/* 3 SIGQUIT */
	SA_KILL|SA_CORE|SA_NORESET|SA_TOLWP,	/* 4 SIGILL */
	SA_KILL|SA_CORE|SA_NORESET|SA_TOLWP,	/* 5 SIGTRAP */
	SA_KILL|SA_CORE,			/* 6 SIGABRT */
	SA_KILL|SA_CORE|SA_TOLWP,		/* 7 SIGEMT */
	SA_KILL|SA_CORE|SA_TOLWP,		/* 8 SIGFPE */
	SA_KILL|SA_CANTMASK|SA_TOALL,		/* 9 SIGKILL */
	SA_KILL|SA_CORE|SA_TOLWP,		/* 10 SIGBUS */
	SA_KILL|SA_CORE|SA_TOLWP,		/* 11 SIGSEGV */
	SA_KILL|SA_CORE|SA_TOLWP,		/* 12 SIGSYS */
	SA_KILL,				/* 13 SIGPIPE */
	SA_KILL,				/* 14 SIGALRM */
	SA_KILL,				/* 15 SIGTERM */
	SA_IGNORE,				/* 16 SIGURG */
	SA_STOP|SA_CANTMASK|SA_TOALL,		/* 17 SIGSTOP */
	SA_STOP|SA_TTYSTOP|SA_TOALL,		/* 18 SIGTSTP */
	SA_IGNORE|SA_CONT|SA_TOALL,		/* 19 SIGCONT */
	SA_IGNORE,				/* 20 SIGCHLD */
	SA_STOP|SA_TTYSTOP|SA_TOALL,		/* 21 SIGTTIN */
	SA_STOP|SA_TTYSTOP|SA_TOALL,		/* 22 SIGTTOU */
	SA_IGNORE,				/* 23 SIGIO */
	SA_KILL,				/* 24 SIGXCPU */
	SA_KILL,				/* 25 SIGXFSZ */
	SA_KILL,				/* 26 SIGVTALRM */
	SA_KILL,				/* 27 SIGPROF */
	SA_IGNORE,				/* 28 SIGWINCH  */
	SA_IGNORE,				/* 29 SIGINFO */
	SA_KILL,				/* 30 SIGUSR1 */
	SA_KILL,				/* 31 SIGUSR2 */
	SA_IGNORE|SA_NORESET,			/* 32 SIGPWR */
	SA_KILL,				/* 33 SIGRTMIN + 0 */
	SA_KILL,				/* 34 SIGRTMIN + 1 */
	SA_KILL,				/* 35 SIGRTMIN + 2 */
	SA_KILL,				/* 36 SIGRTMIN + 3 */
	SA_KILL,				/* 37 SIGRTMIN + 4 */
	SA_KILL,				/* 38 SIGRTMIN + 5 */
	SA_KILL,				/* 39 SIGRTMIN + 6 */
	SA_KILL,				/* 40 SIGRTMIN + 7 */
	SA_KILL,				/* 41 SIGRTMIN + 8 */
	SA_KILL,				/* 42 SIGRTMIN + 9 */
	SA_KILL,				/* 43 SIGRTMIN + 10 */
	SA_KILL,				/* 44 SIGRTMIN + 11 */
	SA_KILL,				/* 45 SIGRTMIN + 12 */
	SA_KILL,				/* 46 SIGRTMIN + 13 */
	SA_KILL,				/* 47 SIGRTMIN + 14 */
	SA_KILL,				/* 48 SIGRTMIN + 15 */
	SA_KILL,				/* 49 SIGRTMIN + 16 */
	SA_KILL,				/* 50 SIGRTMIN + 17 */
	SA_KILL,				/* 51 SIGRTMIN + 18 */
	SA_KILL,				/* 52 SIGRTMIN + 19 */
	SA_KILL,				/* 53 SIGRTMIN + 20 */
	SA_KILL,				/* 54 SIGRTMIN + 21 */
	SA_KILL,				/* 55 SIGRTMIN + 22 */
	SA_KILL,				/* 56 SIGRTMIN + 23 */
	SA_KILL,				/* 57 SIGRTMIN + 24 */
	SA_KILL,				/* 58 SIGRTMIN + 25 */
	SA_KILL,				/* 59 SIGRTMIN + 26 */
	SA_KILL,				/* 60 SIGRTMIN + 27 */
	SA_KILL,				/* 61 SIGRTMIN + 28 */
	SA_KILL,				/* 62 SIGRTMIN + 29 */
	SA_KILL,				/* 63 SIGRTMIN + 30 */
};
#undef	SIGPROP
#else
extern const int sigprop[NSIG];
#endif	/* SIGPROP */
#endif	/* _KERNEL */
#endif	/* !_SYS_SIGNALVAR_H_ */