[PATCH 1/6] introduce kernel_execve

Arnd Bergmann
2006-08-30T12:53:33Z

[-- Attachment #1: kernel-execve-0.5.diff --]
[-- Type: text/plain, Size: 4580 bytes --]

The use of execve() in the kernel is dubious, since it relies
on the __KERNEL_SYSCALLS__ mechanism that stores the result in
a global errno variable. As a first step of getting rid of
this, change all users to a global kernel_execve function that
returns a proper error code.

This function is a terrible hack, and a later patch removes
it again after the kernel syscalls are gone.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Index: linux-cg/init/do_mounts_initrd.c
===================================================================
--- linux-cg.orig/init/do_mounts_initrd.c 2006-08-27 23:17:58.000000000 +0200
+++ linux-cg/init/do_mounts_initrd.c 2006-08-27 23:18:58.000000000 +0200
@@ -1,4 +1,3 @@
-#define __KERNEL_SYSCALLS__
#include <linux/unistd.h>
#include <linux/kernel.h>
#include <linux/fs.h>
@@ -35,7 +34,7 @@
(void) sys_open("/dev/console",O_RDWR,0);
(void) sys_dup(0);
(void) sys_dup(0);
- return execve(shell, argv, envp_init);
+ return kernel_execve(shell, argv, envp_init);
}

static void __init handle_initrd(void)
Index: linux-cg/kernel/kmod.c
===================================================================
--- linux-cg.orig/kernel/kmod.c 2006-08-27 23:17:58.000000000 +0200
+++ linux-cg/kernel/kmod.c 2006-08-27 23:18:58.000000000 +0200
@@ -18,8 +18,6 @@
call_usermodehelper wait flag, and remove exec_usermodehelper.
Rusty Russell <rusty@rustcorp.com.au> Jan 2003
*/
-#define __KERNEL_SYSCALLS__
-
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/syscalls.h>
@@ -150,7 +148,8 @@

retval = -EPERM;
if (current->fs->root)
- retval = execve(sub_info->path, sub_info->argv,sub_info->envp);
+ retval = kernel_execve(sub_info->path,
+ sub_info->argv, sub_info->envp);

/* Exec failed? */
sub_info->retval = retval;
Index: linux-cg/lib/Makefile
===================================================================
--- linux-cg.orig/lib/Makefile 2006-08-27 23:17:58.000000000 +0200
+++ linux-cg/lib/Makefile 2006-08-27 23:18:58.000000000 +0200
@@ -33,6 +33,8 @@
lib-y += dec_and_lock.o
endif

+lib-y += execve.o
+
obj-$(CONFIG_CRC_CCITT) += crc-ccitt.o
obj-$(CONFIG_CRC16) += crc16.o
obj-$(CONFIG_CRC32) += crc32.o
Index: linux-cg/lib/execve.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-cg/lib/execve.c 2006-08-27 23:18:58.000000000 +0200
@@ -0,0 +1,23 @@
+#include <asm/bug.h>
+#include <asm/uaccess.h>
+
+#define __KERNEL_SYSCALLS__
+static int errno __attribute__((unused));
+#include <asm/unistd.h>
+
+#ifdef _syscall3
+int kernel_execve (const char *filename, char *const argv[], char *const envp[])
+ __attribute__((__weak__));
+int kernel_execve (const char *filename, char *const argv[], char *const envp[])
+{
+ mm_segment_t fs = get_fs();
+ int ret;
+
+ WARN_ON(segment_eq(fs, USER_DS));
+ ret = execve(filename, (char **)argv, (char **)envp);
+ if (ret)
+ ret = -errno;
+
+ return ret;
+}
+#endif
Index: linux-cg/init/main.c
===================================================================
--- linux-cg.orig/init/main.c 2006-08-27 23:17:58.000000000 +0200
+++ linux-cg/init/main.c 2006-08-27 23:18:58.000000000 +0200
@@ -9,8 +9,6 @@
* Simplified starting of init: Michael A. Griffith <grif@acm.org>
*/

-#define __KERNEL_SYSCALLS__
-
#include <linux/types.h>
#include <linux/module.h>
#include <linux/proc_fs.h>
@@ -679,7 +677,7 @@
static void run_init_process(char *init_filename)
{
argv_init[0] = init_filename;
- execve(init_filename, argv_init, envp_init);
+ kernel_execve(init_filename, argv_init, envp_init);
}

static int init(void * unused)
Index: linux-cg/arch/sparc64/kernel/power.c
===================================================================
--- linux-cg.orig/arch/sparc64/kernel/power.c 2006-08-27 23:18:53.000000000 +0200
+++ linux-cg/arch/sparc64/kernel/power.c 2006-08-27 23:19:04.000000000 +0200
@@ -4,8 +4,6 @@
* Copyright (C) 1999 David S. Miller (davem@redhat.com)
*/

-#define __KERNEL_SYSCALLS__
-
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
@@ -14,6 +12,7 @@
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/pm.h>
+#include <linux/syscalls.h>

#include <asm/system.h>
#include <asm/auxio.h>
@@ -98,7 +97,7 @@

/* Ok, down we go... */
button_pressed = 0;
- if (execve("/sbin/shutdown", argv, envp) < 0) {
+ if (kernel_execve("/sbin/shutdown", argv, envp) < 0) {
printk("powerd: shutdown execution failed\n");
add_wait_queue(&powerd_wait, &wait);
goto again;

--