Date: Fri, 23 Jul 1999 22:12:29 -0700 (PDT) From: <jkoshy@FreeBSD.org> To: freebsd-hackers@freebsd.org Subject: deny ktrace without read permissions? Message-ID: <199907240512.WAA19120@freefall.freebsd.org>
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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); To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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