When a process is exec:ing mark it with a flag. Check that flag in ptrace

and procfs (and possibly more places in the future) and simply refuse to
fiddle with the execing process. This is an ugly hack, but this far we
haven't been successful in creating a race-free exec.

1 files changed, 10 insertions, 1 deletions

diff --git a/sys/kern/kern_exec.c b/sys/kern/kern_exec.c
index 6bec610b8e2..b8b6b6d479a 100644
--- a/sys/kern/kern_exec.c
+++ b/sys/kern/kern_exec.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kern_exec.c,v 1.62 2001/12/19 08:58:06 art Exp $	*/
+/*	$OpenBSD: kern_exec.c,v 1.63 2002/01/20 11:27:52 art Exp $	*/
 /*	$NetBSD: kern_exec.c,v 1.75 1996/02/09 18:59:28 christos Exp $	*/
 
 /*-
@@ -250,6 +250,12 @@ sys_execve(p, v, retval)
 	extern struct emul emul_native;
 
 	/*
+	 * Cheap solution to complicated problems.
+	 * Mark this process as "leave me alone, I'm execing".
+	 */
+	p->p_flag |= P_INEXEC;
+
+	/*
 	 * figure out the maximum size of an exec header, if necessary.
 	 * XXX should be able to keep LKM code from modifying exec switch
 	 * when we're still using it, but...
@@ -614,6 +620,7 @@ sys_execve(p, v, retval)
 	if (KTRPOINT(p, KTR_EMUL))
 		ktremul(p, p->p_emul->e_name);
 #endif
+	p->p_flag &= ~P_INEXEC;
 	return (0);
 
 bad:
@@ -632,6 +639,7 @@ bad:
 
 freehdr:
 	free(pack.ep_hdr, M_EXEC);
+	p->p_flag &= ~P_INEXEC;
 	return (error);
 
 exec_abort:
@@ -655,6 +663,7 @@ free_pack_abort:
 	exit1(p, -1);
 
 	/* NOTREACHED */
+	p->p_flag &= ~P_INEXEC;
 	return (0);
 }