PR bin/3546 asks that `ktrace(1)' not be allowed on files that do not have
read permissions for the user attempting to execute them.
The intent of this change is to prevent a user from seeing how an
executable with '--x--x--x' perms works by ktrace'ing its execution.
My question to the -hackers is: is this a useful semantic? Would it break
anything if added?
A patch to "/sys/kern/kern_exec.c" that adds this functionality is attached
for those who would like to play with the change.
Regards,
Koshy
Index: /sys/kern/kern_exec.c
===================================================================
RCS file: /home/ncvs/src/sys/kern/kern_exec.c,v
retrieving revision 1.99
diff -u -r1.99 kern_exec.c
--- kern_exec.c 1999/04/27 11:15:55 1.99
+++ kern_exec.c 1999/07/24 10:35:09
@@ -26,6 +26,8 @@
* $Id: kern_exec.c,v 1.99 1999/04/27 11:15:55 phk Exp $
*/
+#include "opt_ktrace.h"
+
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/sysproto.h>
@@ -48,6 +50,9 @@
#include <sys/sysctl.h>
#include <sys/vnode.h>
#include <sys/buf.h>
+#ifdef KTRACE
+#include <sys/ktrace.h>
+#endif
#include <vm/vm.h>
#include <vm/vm_param.h>
@@ -650,6 +655,7 @@
struct vnode *vp = imgp->vp;
struct vattr *attr = imgp->attr;
int error;
+ int mode;
/* Get file attributes */
error = VOP_GETATTR(vp, attr, p->p_ucred, p);
@@ -677,9 +683,14 @@
return (ENOEXEC);
/*
- * Check for execute permission to file based on current credentials.
+ * Check for execute permission to file based on current credentials.
*/
- error = VOP_ACCESS(vp, VEXEC, p->p_ucred, p);
+ mode = VEXEC;
+#ifdef KTRACE
+ if (p->p_traceflag & KTRFAC_MASK)
+ mode |= VREAD;
+#endif
+ error = VOP_ACCESS(vp, mode, p->p_ucred, p);
if (error)
return (error);
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