MFC 302900,302902,302921,303461,304009:

Add a mask of optional ptrace() events.

302900:
Add a test for user signal delivery.

This test verifies we get the correct ptrace event details when a signal
is posted to a traced process from userland.

302902:
Add a mask of optional ptrace() events.

ptrace() now stores a mask of optional events in p_ptevents.  Currently
this mask is a single integer, but it can be expanded into an array of
integers in the future.

Two new ptrace requests can be used to manipulate the event mask:
PT_GET_EVENT_MASK fetches the current event mask and PT_SET_EVENT_MASK
sets the current event mask.

The current set of events include:
- PTRACE_EXEC: trace calls to execve().
- PTRACE_SCE: trace system call entries.
- PTRACE_SCX: trace syscam call exits.
- PTRACE_FORK: trace forks and auto-attach to new child processes.
- PTRACE_LWP: trace LWP events.

The S_PT_SCX and S_PT_SCE events in the procfs p_stops flags have
been replaced by PTRACE_SCE and PTRACE_SCX.  PTRACE_FORK replaces
P_FOLLOW_FORK and PTRACE_LWP replaces P2_LWP_EVENTS.

The PT_FOLLOW_FORK and PT_LWP_EVENTS ptrace requests remain for
compatibility but now simply toggle corresponding flags in the
event mask.

While here, document that PT_SYSCALL, PT_TO_SCE, and PT_TO_SCX both
modify the event mask and continue the traced process.

302921:
Rename PTRACE_SYSCALL to LINUX_PTRACE_SYSCALL.

303461:
Note that not all optional ptrace events use SIGTRAP.

New child processes attached due to PTRACE_FORK use SIGSTOP instead of
SIGTRAP.  All other ptrace events use SIGTRAP.

304009:
Remove description of P_FOLLOWFORK as this flag was removed.

7 files changed, 77 insertions, 28 deletions

diff --git a/sys/kern/kern_exec.c b/sys/kern/kern_exec.c
index 6466a3e..df8e903 100644
--- a/sys/kern/kern_exec.c
+++ b/sys/kern/kern_exec.c
@@ -53,6 +53,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/priv.h>
 #include <sys/proc.h>
 #include <sys/pioctl.h>
+#include <sys/ptrace.h>
 #include <sys/namei.h>
 #include <sys/resourcevar.h>
 #include <sys/rwlock.h>
@@ -905,7 +906,8 @@ exec_fail_dealloc:
 
 	if (error == 0) {
 		PROC_LOCK(p);
-		td->td_dbgflags |= TDB_EXEC;
+		if (p->p_ptevents & PTRACE_EXEC)
+			td->td_dbgflags |= TDB_EXEC;
 		PROC_UNLOCK(p);
 
 		/*
diff --git a/sys/kern/kern_exit.c b/sys/kern/kern_exit.c
index 929c2c0..3b7b9da 100644
--- a/sys/kern/kern_exit.c
+++ b/sys/kern/kern_exit.c
@@ -338,6 +338,7 @@ exit1(struct thread *td, int rval, int signo)
 	PROC_LOCK(p);
 	stopprofclock(p);
 	p->p_flag &= ~(P_TRACED | P_PPWAIT | P_PPTRACE);
+	p->p_ptevents = 0;
 
 	/*
 	 * Stop the real interval timer.  If the handler is currently
@@ -475,6 +476,7 @@ exit1(struct thread *td, int rval, int signo)
 			 */
 			clear_orphan(q);
 			q->p_flag &= ~(P_TRACED | P_STOPPED_TRACE);
+			q->p_ptevents = 0;
 			FOREACH_THREAD_IN_PROC(q, tdt)
 				tdt->td_dbgflags &= ~TDB_SUSPEND;
 			kern_psignal(q, SIGKILL);
diff --git a/sys/kern/kern_fork.c b/sys/kern/kern_fork.c
index 2c98551..84bef4f 100644
--- a/sys/kern/kern_fork.c
+++ b/sys/kern/kern_fork.c
@@ -414,6 +414,7 @@ do_fork(struct thread *td, struct fork_req *fr, struct proc *p2, struct thread *
 
 	bzero(&p2->p_startzero,
 	    __rangeof(struct proc, p_startzero, p_endzero));
+	p2->p_ptevents = 0;
 
 	/* Tell the prison that we exist. */
 	prison_proc_hold(p2->p_ucred->cr_prison);
@@ -720,8 +721,7 @@ do_fork(struct thread *td, struct fork_req *fr, struct proc *p2, struct thread *
 	 * but before we wait for the debugger.
 	 */
 	_PHOLD(p2);
-	if ((p1->p_flag & (P_TRACED | P_FOLLOWFORK)) == (P_TRACED |
-	    P_FOLLOWFORK)) {
+	if (p1->p_ptevents & PTRACE_FORK) {
 		/*
 		 * Arrange for debugger to receive the fork event.
 		 *
@@ -1068,14 +1068,14 @@ fork_return(struct thread *td, struct trapframe *frame)
 	if (td->td_dbgflags & TDB_STOPATFORK) {
 		sx_xlock(&proctree_lock);
 		PROC_LOCK(p);
-		if ((p->p_pptr->p_flag & (P_TRACED | P_FOLLOWFORK)) ==
-		    (P_TRACED | P_FOLLOWFORK)) {
+		if (p->p_pptr->p_ptevents & PTRACE_FORK) {
 			/*
 			 * If debugger still wants auto-attach for the
 			 * parent's children, do it now.
 			 */
 			dbg = p->p_pptr->p_pptr;
 			p->p_flag |= P_TRACED;
+			p->p_ptevents = PTRACE_DEFAULT;
 			p->p_oppid = p->p_pptr->p_pid;
 			CTR2(KTR_PTRACE,
 		    "fork_return: attaching to new child pid %d: oppid %d",
@@ -1102,7 +1102,7 @@ fork_return(struct thread *td, struct trapframe *frame)
 		PROC_LOCK(p);
 		td->td_dbgflags |= TDB_SCX;
 		_STOPEVENT(p, S_SCX, td->td_dbg_sc_code);
-		if ((p->p_stops & S_PT_SCX) != 0 ||
+		if ((p->p_ptevents & PTRACE_SCX) != 0 ||
 		    (td->td_dbgflags & TDB_BORN) != 0)
 			ptracestop(td, SIGTRAP);
 		td->td_dbgflags &= ~(TDB_SCX | TDB_BORN);
diff --git a/sys/kern/kern_sig.c b/sys/kern/kern_sig.c
index 2a5e6de..1da4b99 100644
--- a/sys/kern/kern_sig.c
+++ b/sys/kern/kern_sig.c
@@ -2191,9 +2191,10 @@ tdsendsignal(struct proc *p, struct thread *td, int sig, ksiginfo_t *ksi)
 	    !((prop & SA_CONT) && (p->p_flag & P_STOPPED_SIG)))
 		return (ret);
 	/*
-	 * SIGKILL: Remove procfs STOPEVENTs.
+	 * SIGKILL: Remove procfs STOPEVENTs and ptrace events.
 	 */
 	if (sig == SIGKILL) {
+		p->p_ptevents = 0;
 		/* from procfs_ioctl.c: PIOCBIC */
 		p->p_stops = 0;
 		/* from procfs_ioctl.c: PIOCCONT */
diff --git a/sys/kern/kern_thr.c b/sys/kern/kern_thr.c
index 293574c..10e7b2d 100644
--- a/sys/kern/kern_thr.c
+++ b/sys/kern/kern_thr.c
@@ -36,6 +36,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/priv.h>
 #include <sys/proc.h>
 #include <sys/posix4.h>
+#include <sys/ptrace.h>
 #include <sys/racct.h>
 #include <sys/resourcevar.h>
 #include <sys/rwlock.h>
@@ -254,7 +255,7 @@ thread_create(struct thread *td, struct rtprio *rtp,
 	thread_unlock(td);
 	if (P_SHOULDSTOP(p))
 		newtd->td_flags |= TDF_ASTPENDING | TDF_NEEDSUSPCHK;
-	if (p->p_flag2 & P2_LWP_EVENTS)
+	if (p->p_ptevents & PTRACE_LWP)
 		newtd->td_dbgflags |= TDB_BORN;
 
 	/*
@@ -354,7 +355,7 @@ kern_thr_exit(struct thread *td)
 
 	p->p_pendingexits++;
 	td->td_dbgflags |= TDB_EXIT;
-	if (p->p_flag & P_TRACED && p->p_flag2 & P2_LWP_EVENTS)
+	if (p->p_ptevents & PTRACE_LWP)
 		ptracestop(td, SIGTRAP);
 	PROC_UNLOCK(p);
 	tidhash_remove(td);
diff --git a/sys/kern/subr_syscall.c b/sys/kern/subr_syscall.c
index f7bbdfb..aad2a1e 100644
--- a/sys/kern/subr_syscall.c
+++ b/sys/kern/subr_syscall.c
@@ -87,7 +87,7 @@ syscallenter(struct thread *td, struct syscall_args *sa)
 			PROC_LOCK(p);
 			td->td_dbg_sc_code = sa->code;
 			td->td_dbg_sc_narg = sa->narg;
-			if (p->p_stops & S_PT_SCE)
+			if (p->p_ptevents & PTRACE_SCE)
 				ptracestop((td), SIGTRAP);
 			PROC_UNLOCK(p);
 		}
@@ -208,7 +208,7 @@ syscallret(struct thread *td, int error, struct syscall_args *sa)
 		 */
 		if (traced &&
 		    ((td->td_dbgflags & (TDB_FORK | TDB_EXEC)) != 0 ||
-		    (p->p_stops & S_PT_SCX) != 0))
+		    (p->p_ptevents & PTRACE_SCX) != 0))
 			ptracestop(td, SIGTRAP);
 		td->td_dbgflags &= ~(TDB_SCX | TDB_EXEC | TDB_FORK);
 		PROC_UNLOCK(p);
diff --git a/sys/kern/sys_process.c b/sys/kern/sys_process.c
index af71ea8..f1477ce 100644
--- a/sys/kern/sys_process.c
+++ b/sys/kern/sys_process.c
@@ -586,6 +586,7 @@ sys_ptrace(struct thread *td, struct ptrace_args *uap)
 		struct ptrace_lwpinfo32 pl32;
 		struct ptrace_vm_entry32 pve32;
 #endif
+		int ptevents;
 	} r;
 	void *addr;
 	int error = 0;
@@ -600,6 +601,7 @@ sys_ptrace(struct thread *td, struct ptrace_args *uap)
 	AUDIT_ARG_VALUE(uap->data);
 	addr = &r;
 	switch (uap->req) {
+	case PT_GET_EVENT_MASK:
 	case PT_GETREGS:
 	case PT_GETFPREGS:
 	case PT_GETDBREGS:
@@ -614,6 +616,12 @@ sys_ptrace(struct thread *td, struct ptrace_args *uap)
 	case PT_SETDBREGS:
 		error = COPYIN(uap->addr, &r.dbreg, sizeof r.dbreg);
 		break;
+	case PT_SET_EVENT_MASK:
+		if (uap->data != sizeof(r.ptevents))
+			error = EINVAL;
+		else
+			error = copyin(uap->addr, &r.ptevents, uap->data);
+		break;
 	case PT_IO:
 		error = COPYIN(uap->addr, &r.piod, sizeof r.piod);
 		break;
@@ -647,7 +655,12 @@ sys_ptrace(struct thread *td, struct ptrace_args *uap)
 	case PT_GETDBREGS:
 		error = COPYOUT(&r.dbreg, uap->addr, sizeof r.dbreg);
 		break;
+	case PT_GET_EVENT_MASK:
+		/* NB: The size in uap->data is validated in kern_ptrace(). */
+		error = copyout(&r.ptevents, uap->addr, uap->data);
+		break;
 	case PT_LWPINFO:
+		/* NB: The size in uap->data is validated in kern_ptrace(). */
 		error = copyout(&r.pl, uap->addr, uap->data);
 		break;
 	}
@@ -711,6 +724,8 @@ kern_ptrace(struct thread *td, int req, pid_t pid, void *addr, int data)
 	case PT_SYSCALL:
 	case PT_FOLLOW_FORK:
 	case PT_LWP_EVENTS:
+	case PT_GET_EVENT_MASK:
+	case PT_SET_EVENT_MASK:
 	case PT_DETACH:
 		sx_xlock(&proctree_lock);
 		proctree_locked = 1;
@@ -885,6 +900,7 @@ kern_ptrace(struct thread *td, int req, pid_t pid, void *addr, int data)
 	case PT_TRACE_ME:
 		/* set my trace flag and "owner" so it can read/write me */
 		p->p_flag |= P_TRACED;
+		p->p_ptevents = PTRACE_DEFAULT;
 		if (p->p_flag & P_PPWAIT)
 			p->p_flag |= P_PPTRACE;
 		p->p_oppid = p->p_pptr->p_pid;
@@ -903,6 +919,7 @@ kern_ptrace(struct thread *td, int req, pid_t pid, void *addr, int data)
 		 * on a "detach".
 		 */
 		p->p_flag |= P_TRACED;
+		p->p_ptevents = PTRACE_DEFAULT;
 		p->p_oppid = p->p_pptr->p_pid;
 		if (p->p_pptr != td->td_proc) {
 			proc_reparent(p, td->td_proc);
@@ -941,24 +958,50 @@ kern_ptrace(struct thread *td, int req, pid_t pid, void *addr, int data)
 
 	case PT_FOLLOW_FORK:
 		CTR3(KTR_PTRACE, "PT_FOLLOW_FORK: pid %d %s -> %s", p->p_pid,
-		    p->p_flag & P_FOLLOWFORK ? "enabled" : "disabled",
+		    p->p_ptevents & PTRACE_FORK ? "enabled" : "disabled",
 		    data ? "enabled" : "disabled");
 		if (data)
-			p->p_flag |= P_FOLLOWFORK;
+			p->p_ptevents |= PTRACE_FORK;
 		else
-			p->p_flag &= ~P_FOLLOWFORK;
+			p->p_ptevents &= ~PTRACE_FORK;
 		break;
 
 	case PT_LWP_EVENTS:
 		CTR3(KTR_PTRACE, "PT_LWP_EVENTS: pid %d %s -> %s", p->p_pid,
-		    p->p_flag2 & P2_LWP_EVENTS ? "enabled" : "disabled",
+		    p->p_ptevents & PTRACE_LWP ? "enabled" : "disabled",
 		    data ? "enabled" : "disabled");
 		if (data)
-			p->p_flag2 |= P2_LWP_EVENTS;
+			p->p_ptevents |= PTRACE_LWP;
 		else
-			p->p_flag2 &= ~P2_LWP_EVENTS;
+			p->p_ptevents &= ~PTRACE_LWP;
+		break;
+
+	case PT_GET_EVENT_MASK:
+		if (data != sizeof(p->p_ptevents)) {
+			error = EINVAL;
+			break;
+		}
+		CTR2(KTR_PTRACE, "PT_GET_EVENT_MASK: pid %d mask %#x", p->p_pid,
+		    p->p_ptevents);
+		*(int *)addr = p->p_ptevents;
 		break;
 
+	case PT_SET_EVENT_MASK:
+		if (data != sizeof(p->p_ptevents)) {
+			error = EINVAL;
+			break;
+		}
+		tmp = *(int *)addr;
+		if ((tmp & ~(PTRACE_EXEC | PTRACE_SCE | PTRACE_SCX |
+		    PTRACE_FORK | PTRACE_LWP)) != 0) {
+			error = EINVAL;
+			break;
+		}
+		CTR3(KTR_PTRACE, "PT_SET_EVENT_MASK: pid %d mask %#x -> %#x",
+		    p->p_pid, p->p_ptevents, tmp);
+		p->p_ptevents = tmp;
+		break;
+		
 	case PT_STEP:
 	case PT_CONTINUE:
 	case PT_TO_SCE:
@@ -991,24 +1034,24 @@ kern_ptrace(struct thread *td, int req, pid_t pid, void *addr, int data)
 			}
 			switch (req) {
 			case PT_TO_SCE:
-				p->p_stops |= S_PT_SCE;
+				p->p_ptevents |= PTRACE_SCE;
 				CTR4(KTR_PTRACE,
-		    "PT_TO_SCE: pid %d, stops = %#x, PC = %#lx, sig = %d",
-				    p->p_pid, p->p_stops,
+		    "PT_TO_SCE: pid %d, events = %#x, PC = %#lx, sig = %d",
+				    p->p_pid, p->p_ptevents,
 				    (u_long)(uintfptr_t)addr, data);
 				break;
 			case PT_TO_SCX:
-				p->p_stops |= S_PT_SCX;
+				p->p_ptevents |= PTRACE_SCX;
 				CTR4(KTR_PTRACE,
-		    "PT_TO_SCX: pid %d, stops = %#x, PC = %#lx, sig = %d",
-				    p->p_pid, p->p_stops,
+		    "PT_TO_SCX: pid %d, events = %#x, PC = %#lx, sig = %d",
+				    p->p_pid, p->p_ptevents,
 				    (u_long)(uintfptr_t)addr, data);
 				break;
 			case PT_SYSCALL:
-				p->p_stops |= S_PT_SCE | S_PT_SCX;
+				p->p_ptevents |= PTRACE_SYSCALL;
 				CTR4(KTR_PTRACE,
-		    "PT_SYSCALL: pid %d, stops = %#x, PC = %#lx, sig = %d",
-				    p->p_pid, p->p_stops,
+		    "PT_SYSCALL: pid %d, events = %#x, PC = %#lx, sig = %d",
+				    p->p_pid, p->p_ptevents,
 				    (u_long)(uintfptr_t)addr, data);
 				break;
 			case PT_CONTINUE:
@@ -1027,7 +1070,7 @@ kern_ptrace(struct thread *td, int req, pid_t pid, void *addr, int data)
 			 * parent.  Otherwise the debugee will be set
 			 * as an orphan of the debugger.
 			 */
-			p->p_flag &= ~(P_TRACED | P_WAITED | P_FOLLOWFORK);
+			p->p_flag &= ~(P_TRACED | P_WAITED);
 			if (p->p_oppid != p->p_pptr->p_pid) {
 				PROC_LOCK(p->p_pptr);
 				sigqueue_take(p->p_ksi);
@@ -1044,7 +1087,7 @@ kern_ptrace(struct thread *td, int req, pid_t pid, void *addr, int data)
 				CTR2(KTR_PTRACE, "PT_DETACH: pid %d, sig %d",
 				    p->p_pid, data);
 			p->p_oppid = 0;
-			p->p_stops = 0;
+			p->p_ptevents = 0;
 
 			/* should we send SIGCHLD? */
 			/* childproc_continued(p); */