socsvn commit: r240113 - soc2012/gpf/pefs_head/head/sys/kern

[gpf at FreeBSD.org]

Author: gpf
Date: Sun Aug  5 19:00:53 2012
New Revision: 240113
URL: http://svnweb.FreeBSD.org/socsvn/?view=rev&rev=240113

Log:
  kern_exec.c hack:
  
  During an exec(), kernel checks if sysctl var "vfs.pefs.exec.enable" exists
  and is turned on. If it is active, we check the schg flag of the executable.
  
  For the moment, we simply print a "denied" message. Next patch will
  return proper error code and fail in a graceful manner.
  
  The pefs specific sysctl var is used to ease development so it's just
  temporary.
  
  If the file being executed is a shell script, only the respective
  interpreter is checked for the schg flag, not the script itself.
  
  work in progress
  

Modified:
  soc2012/gpf/pefs_head/head/sys/kern/kern_exec.c

Modified: soc2012/gpf/pefs_head/head/sys/kern/kern_exec.c
==============================================================================
--- soc2012/gpf/pefs_head/head/sys/kern/kern_exec.c	Sun Aug  5 17:30:17 2012	(r240112)
+++ soc2012/gpf/pefs_head/head/sys/kern/kern_exec.c	Sun Aug  5 19:00:53 2012	(r240113)
@@ -122,7 +122,7 @@
     NULL, 0, sysctl_kern_stackprot, "I", "");
 
 u_long ps_arg_cache_limit = PAGE_SIZE / 16;
-SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 
+SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW,
     &ps_arg_cache_limit, 0, "");
 
 static int map_at_zero = 0;
@@ -186,9 +186,9 @@
 
 #ifndef _SYS_SYSPROTO_H_
 struct execve_args {
-	char    *fname; 
+	char    *fname;
 	char    **argv;
-	char    **envv; 
+	char    **envv;
 };
 #endif
 
@@ -548,6 +548,24 @@
 		goto interpret;
 	}
 
+	{
+		int enabled, rval;
+		size_t enabled_len;
+
+		rval = kernel_sysctlbyname(td, "vfs.pefs.exec.enable",
+					&enabled, &enabled_len, NULL, 0, NULL, 0);
+		//printf("sysctl vfs.pefs.exec.enable=%d returns %d\n", enabled,
+			//rval);
+		if (rval == 0 && enabled != 0) {
+			printf("checking flag for %s\n", args->fname);
+			if ((imgp->attr->va_flags & SF_IMMUTABLE) == 0) {
+				printf("denied!\n");
+				//error = ...
+				//goto exec_fail_dealloc;
+			}
+		}
+	}
+
 	/*
 	 * NB: We unlock the vnode here because it is believed that none
 	 * of the sv_copyout_strings/sv_fixup operations require the vnode.
@@ -821,7 +839,7 @@
 
 	/* Set values passed into the program in registers. */
 	if (p->p_sysent->sv_setregs)
-		(*p->p_sysent->sv_setregs)(td, imgp, 
+		(*p->p_sysent->sv_setregs)(td, imgp,
 		    (u_long)(uintptr_t)stack_base);
 	else
 		exec_setregs(td, imgp, (u_long)(uintptr_t)stack_base);
@@ -1160,7 +1178,7 @@
 		}
 		if ((error = copyinstr(argp, args->endp,
 		    args->stringspace, &length))) {
-			if (error == ENAMETOOLONG) 
+			if (error == ENAMETOOLONG)
 				error = E2BIG;
 			goto err_exit;
 		}