2bd3a997be
To avoid potential problems with an empty /dev open /dev/console from rootfs instead of waiting to mount our root filesystem and mounting it there. This effectively guarantees that there will be a device node, and it won't be on a filesystem that we will ever unmount, so there are no issues with leaving /dev/console open and pinning the filesystem. This is actually more effective than automatically mounting devtmpfs on /dev because it removes removes the occasionally problematic assumption that /dev/console exists from the boot code. With this patch I was able to throw busybox on my /boot partition (which has no /dev directory) and boot into userspace without problems. The only possible negative consequence I can think of is that someone out there deliberately used did not use a character device that is major 5 minor 2 for /dev/console. Does anyone know of a situation in which that could make sense? Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
126 lines
3.1 KiB
C
126 lines
3.1 KiB
C
#include <linux/unistd.h>
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#include <linux/kernel.h>
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#include <linux/fs.h>
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#include <linux/minix_fs.h>
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#include <linux/ext2_fs.h>
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#include <linux/romfs_fs.h>
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#include <linux/initrd.h>
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#include <linux/sched.h>
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#include <linux/freezer.h>
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#include "do_mounts.h"
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unsigned long initrd_start, initrd_end;
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int initrd_below_start_ok;
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unsigned int real_root_dev; /* do_proc_dointvec cannot handle kdev_t */
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static int __initdata old_fd, root_fd;
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static int __initdata mount_initrd = 1;
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static int __init no_initrd(char *str)
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{
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mount_initrd = 0;
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return 1;
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}
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__setup("noinitrd", no_initrd);
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static int __init do_linuxrc(void * shell)
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{
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static char *argv[] = { "linuxrc", NULL, };
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extern char * envp_init[];
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sys_close(old_fd);sys_close(root_fd);
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sys_setsid();
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return kernel_execve(shell, argv, envp_init);
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}
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static void __init handle_initrd(void)
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{
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int error;
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int pid;
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real_root_dev = new_encode_dev(ROOT_DEV);
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create_dev("/dev/root.old", Root_RAM0);
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/* mount initrd on rootfs' /root */
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mount_block_root("/dev/root.old", root_mountflags & ~MS_RDONLY);
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sys_mkdir("/old", 0700);
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root_fd = sys_open("/", 0, 0);
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old_fd = sys_open("/old", 0, 0);
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/* move initrd over / and chdir/chroot in initrd root */
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sys_chdir("/root");
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sys_mount(".", "/", NULL, MS_MOVE, NULL);
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sys_chroot(".");
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/*
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* In case that a resume from disk is carried out by linuxrc or one of
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* its children, we need to tell the freezer not to wait for us.
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*/
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current->flags |= PF_FREEZER_SKIP;
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pid = kernel_thread(do_linuxrc, "/linuxrc", SIGCHLD);
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if (pid > 0)
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while (pid != sys_wait4(-1, NULL, 0, NULL))
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yield();
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current->flags &= ~PF_FREEZER_SKIP;
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/* move initrd to rootfs' /old */
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sys_fchdir(old_fd);
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sys_mount("/", ".", NULL, MS_MOVE, NULL);
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/* switch root and cwd back to / of rootfs */
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sys_fchdir(root_fd);
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sys_chroot(".");
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sys_close(old_fd);
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sys_close(root_fd);
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if (new_decode_dev(real_root_dev) == Root_RAM0) {
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sys_chdir("/old");
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return;
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}
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ROOT_DEV = new_decode_dev(real_root_dev);
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mount_root();
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printk(KERN_NOTICE "Trying to move old root to /initrd ... ");
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error = sys_mount("/old", "/root/initrd", NULL, MS_MOVE, NULL);
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if (!error)
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printk("okay\n");
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else {
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int fd = sys_open("/dev/root.old", O_RDWR, 0);
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if (error == -ENOENT)
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printk("/initrd does not exist. Ignored.\n");
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else
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printk("failed\n");
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printk(KERN_NOTICE "Unmounting old root\n");
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sys_umount("/old", MNT_DETACH);
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printk(KERN_NOTICE "Trying to free ramdisk memory ... ");
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if (fd < 0) {
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error = fd;
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} else {
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error = sys_ioctl(fd, BLKFLSBUF, 0);
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sys_close(fd);
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}
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printk(!error ? "okay\n" : "failed\n");
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}
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}
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int __init initrd_load(void)
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{
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if (mount_initrd) {
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create_dev("/dev/ram", Root_RAM0);
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/*
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* Load the initrd data into /dev/ram0. Execute it as initrd
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* unless /dev/ram0 is supposed to be our actual root device,
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* in that case the ram disk is just set up here, and gets
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* mounted in the normal path.
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*/
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if (rd_load_image("/initrd.image") && ROOT_DEV != Root_RAM0) {
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sys_unlink("/initrd.image");
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handle_initrd();
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return 1;
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}
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}
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sys_unlink("/initrd.image");
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return 0;
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}
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