1 files changed, 75 insertions, 0 deletions

diff --git a/sys/kern/kern_proc.c b/sys/kern/kern_proc.c
index d74295269870..0ff776cf662d 100644
--- a/sys/kern/kern_proc.c
+++ b/sys/kern/kern_proc.c
@@ -2962,6 +2962,77 @@ sysctl_kern_proc_sigtramp(SYSCTL_HANDLER_ARGS)
 	return (error);
 }
 
+static int
+sysctl_kern_proc_sigfastblk(SYSCTL_HANDLER_ARGS)
+{
+	int *name = (int *)arg1;
+	u_int namelen = arg2;
+	pid_t pid;
+	struct proc *p;
+	struct thread *td1;
+	uintptr_t addr;
+#ifdef COMPAT_FREEBSD32
+	uint32_t addr32;
+#endif
+	int error;
+
+	if (namelen != 1 || req->newptr != NULL)
+		return (EINVAL);
+
+	pid = (pid_t)name[0];
+	error = pget(pid, PGET_HOLD | PGET_NOTWEXIT | PGET_CANDEBUG, &p);
+	if (error != 0)
+		return (error);
+
+	PROC_LOCK(p);
+#ifdef COMPAT_FREEBSD32
+	if (SV_CURPROC_FLAG(SV_ILP32)) {
+		if (!SV_PROC_FLAG(p, SV_ILP32)) {
+			error = EINVAL;
+			goto errlocked;
+		}
+	}
+#endif
+	if (pid <= PID_MAX) {
+		td1 = FIRST_THREAD_IN_PROC(p);
+	} else {
+		FOREACH_THREAD_IN_PROC(p, td1) {
+			if (td1->td_tid == pid)
+				break;
+		}
+	}
+	if (td1 == NULL) {
+		error = ESRCH;
+		goto errlocked;
+	}
+	/*
+	 * The access to the private thread flags.  It is fine as far
+	 * as no out-of-thin-air values are read from td_pflags, and
+	 * usermode read of the td_sigblock_ptr is racy inherently,
+	 * since target process might have already changed it
+	 * meantime.
+	 */
+	if ((td1->td_pflags & TDP_SIGFASTBLOCK) != 0)
+		addr = (uintptr_t)td1->td_sigblock_ptr;
+	else
+		error = ENOTTY;
+
+errlocked:
+	_PRELE(p);
+	PROC_UNLOCK(p);
+	if (error != 0)
+		return (error);
+
+#ifdef COMPAT_FREEBSD32
+	if (SV_CURPROC_FLAG(SV_ILP32)) {
+		addr32 = addr;
+		error = SYSCTL_OUT(req, &addr32, sizeof(addr32));
+	} else
+#endif
+		error = SYSCTL_OUT(req, &addr, sizeof(addr));
+	return (error);
+}
+
 SYSCTL_NODE(_kern, KERN_PROC, proc, CTLFLAG_RD,  0, "Process table");
 
 SYSCTL_PROC(_kern_proc, KERN_PROC_ALL, all, CTLFLAG_RD|CTLTYPE_STRUCT|
@@ -3075,6 +3146,10 @@ static SYSCTL_NODE(_kern_proc, KERN_PROC_SIGTRAMP, sigtramp, CTLFLAG_RD |
 	CTLFLAG_MPSAFE, sysctl_kern_proc_sigtramp,
 	"Process signal trampoline location");
 
+static SYSCTL_NODE(_kern_proc, KERN_PROC_SIGFASTBLK, sigfastblk, CTLFLAG_RD |
+	CTLFLAG_ANYBODY | CTLFLAG_MPSAFE, sysctl_kern_proc_sigfastblk,
+	"Thread sigfastblock address");
+
 int allproc_gen;
 
 /*