From 9732458f3518c58a25eba7cdca2ca3d7e2012885 Mon Sep 17 00:00:00 2001
From: Mikolaj Golub <trociny@FreeBSD.org>
Date: Sun, 27 Nov 2011 17:05:26 +0000
Subject: [PATCH] Add sysctl to retrieve ps_strings structure location of
 another process.

Suggested by:	kib
Reviewed by:	kib
---
 sys/kern/kern_proc.c | 57 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 57 insertions(+)

diff --git a/sys/kern/kern_proc.c b/sys/kern/kern_proc.c
index c54908e5fc5..0edcc25ee25 100644
--- a/sys/kern/kern_proc.c
+++ b/sys/kern/kern_proc.c
@@ -2434,6 +2434,59 @@ sysctl_kern_proc_rlimit(SYSCTL_HANDLER_ARGS)
 	return (error);
 }
 
+/*
+ * This sysctl allows a process to retrieve ps_strings structure location of
+ * another process.
+ */
+static int
+sysctl_kern_proc_ps_strings(SYSCTL_HANDLER_ARGS)
+{
+	int *name = (int*) arg1;
+	u_int namelen = arg2;
+	struct proc *p;
+	vm_offset_t ps_strings;
+	int error;
+#ifdef COMPAT_FREEBSD32
+	uint32_t ps_strings32;
+#endif
+
+	if (namelen != 1)
+		return (EINVAL);
+
+	p = pfind((pid_t)name[0]);
+	if (p == NULL)
+		return (ESRCH);
+	if (p->p_flag & P_WEXIT) {
+		PROC_UNLOCK(p);
+		return (ESRCH);
+	}
+	if ((error = p_cansee(curthread, p)) != 0) {
+		PROC_UNLOCK(p);
+		return (error);
+	}
+	if ((p->p_flag & P_SYSTEM) != 0) {
+		PROC_UNLOCK(p);
+		return (0);
+	}
+#ifdef COMPAT_FREEBSD32
+	if ((req->flags & SCTL_MASK32) != 0) {
+		/*
+		 * We return 0 if the 32 bit emulation request is for a 64 bit
+		 * process.
+		 */
+		ps_strings32 = SV_PROC_FLAG(p, SV_ILP32) != 0 ?
+		    PTROUT(p->p_sysent->sv_psstrings) : 0;
+		PROC_UNLOCK(p);
+		error = SYSCTL_OUT(req, &ps_strings32, sizeof(ps_strings32));
+		return (error);
+	}
+#endif
+	ps_strings = p->p_sysent->sv_psstrings;
+	PROC_UNLOCK(p);
+	error = SYSCTL_OUT(req, &ps_strings, sizeof(ps_strings));
+	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|
@@ -2532,3 +2585,7 @@ static SYSCTL_NODE(_kern_proc, KERN_PROC_GROUPS, groups, CTLFLAG_RD |
 
 static SYSCTL_NODE(_kern_proc, KERN_PROC_RLIMIT, rlimit, CTLFLAG_RD |
 	CTLFLAG_MPSAFE, sysctl_kern_proc_rlimit, "Process resource limits");
+
+static SYSCTL_NODE(_kern_proc, KERN_PROC_PS_STRINGS, ps_strings,
+	CTLFLAG_RW | CTLFLAG_ANYBODY | CTLFLAG_MPSAFE,
+	sysctl_kern_proc_ps_strings, "Process ps_strings location");