linux-stable/init/do_mounts.c
Justin Stitt 07f8230b4b init: replace deprecated strncpy with strscpy_pad
strncpy() is deprecated for use on NUL-terminated destination strings
[1] and as such we should prefer more robust and less ambiguous string
interfaces.

data_page wants to be NUL-terminated and NUL-padded, use strscpy_pad to
provide both of these. data_page no longer awkwardly relies on
init_mount to perform its NUL-termination, although that sanity check is
left unchanged.

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
Link: https://github.com/KSPP/linux/issues/90
Cc:  <linux-hardening@vger.kernel.org>
Signed-off-by: Justin Stitt <justinstitt@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20240402-strncpy-init-do_mounts-c-v1-1-e16d7bc20974@google.com
Signed-off-by: Kees Cook <keescook@chromium.org>
2024-04-30 10:34:29 -07:00

521 lines
11 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/ctype.h>
#include <linux/fd.h>
#include <linux/tty.h>
#include <linux/suspend.h>
#include <linux/root_dev.h>
#include <linux/security.h>
#include <linux/delay.h>
#include <linux/mount.h>
#include <linux/device.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/initrd.h>
#include <linux/async.h>
#include <linux/fs_struct.h>
#include <linux/slab.h>
#include <linux/ramfs.h>
#include <linux/shmem_fs.h>
#include <linux/ktime.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_fs_sb.h>
#include <linux/nfs_mount.h>
#include <linux/raid/detect.h>
#include <uapi/linux/mount.h>
#include "do_mounts.h"
int root_mountflags = MS_RDONLY | MS_SILENT;
static char __initdata saved_root_name[64];
static int root_wait;
dev_t ROOT_DEV;
static int __init load_ramdisk(char *str)
{
pr_warn("ignoring the deprecated load_ramdisk= option\n");
return 1;
}
__setup("load_ramdisk=", load_ramdisk);
static int __init readonly(char *str)
{
if (*str)
return 0;
root_mountflags |= MS_RDONLY;
return 1;
}
static int __init readwrite(char *str)
{
if (*str)
return 0;
root_mountflags &= ~MS_RDONLY;
return 1;
}
__setup("ro", readonly);
__setup("rw", readwrite);
static int __init root_dev_setup(char *line)
{
strscpy(saved_root_name, line, sizeof(saved_root_name));
return 1;
}
__setup("root=", root_dev_setup);
static int __init rootwait_setup(char *str)
{
if (*str)
return 0;
root_wait = -1;
return 1;
}
__setup("rootwait", rootwait_setup);
static int __init rootwait_timeout_setup(char *str)
{
int sec;
if (kstrtoint(str, 0, &sec) || sec < 0) {
pr_warn("ignoring invalid rootwait value\n");
goto ignore;
}
if (check_mul_overflow(sec, MSEC_PER_SEC, &root_wait)) {
pr_warn("ignoring excessive rootwait value\n");
goto ignore;
}
return 1;
ignore:
/* Fallback to indefinite wait */
root_wait = -1;
return 1;
}
__setup("rootwait=", rootwait_timeout_setup);
static char * __initdata root_mount_data;
static int __init root_data_setup(char *str)
{
root_mount_data = str;
return 1;
}
static char * __initdata root_fs_names;
static int __init fs_names_setup(char *str)
{
root_fs_names = str;
return 1;
}
static unsigned int __initdata root_delay;
static int __init root_delay_setup(char *str)
{
root_delay = simple_strtoul(str, NULL, 0);
return 1;
}
__setup("rootflags=", root_data_setup);
__setup("rootfstype=", fs_names_setup);
__setup("rootdelay=", root_delay_setup);
/* This can return zero length strings. Caller should check */
static int __init split_fs_names(char *page, size_t size)
{
int count = 1;
char *p = page;
strscpy(p, root_fs_names, size);
while (*p++) {
if (p[-1] == ',') {
p[-1] = '\0';
count++;
}
}
return count;
}
static int __init do_mount_root(const char *name, const char *fs,
const int flags, const void *data)
{
struct super_block *s;
struct page *p = NULL;
char *data_page = NULL;
int ret;
if (data) {
/* init_mount() requires a full page as fifth argument */
p = alloc_page(GFP_KERNEL);
if (!p)
return -ENOMEM;
data_page = page_address(p);
strscpy_pad(data_page, data, PAGE_SIZE);
}
ret = init_mount(name, "/root", fs, flags, data_page);
if (ret)
goto out;
init_chdir("/root");
s = current->fs->pwd.dentry->d_sb;
ROOT_DEV = s->s_dev;
printk(KERN_INFO
"VFS: Mounted root (%s filesystem)%s on device %u:%u.\n",
s->s_type->name,
sb_rdonly(s) ? " readonly" : "",
MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
out:
if (p)
put_page(p);
return ret;
}
void __init mount_root_generic(char *name, char *pretty_name, int flags)
{
struct page *page = alloc_page(GFP_KERNEL);
char *fs_names = page_address(page);
char *p;
char b[BDEVNAME_SIZE];
int num_fs, i;
scnprintf(b, BDEVNAME_SIZE, "unknown-block(%u,%u)",
MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
if (root_fs_names)
num_fs = split_fs_names(fs_names, PAGE_SIZE);
else
num_fs = list_bdev_fs_names(fs_names, PAGE_SIZE);
retry:
for (i = 0, p = fs_names; i < num_fs; i++, p += strlen(p)+1) {
int err;
if (!*p)
continue;
err = do_mount_root(name, p, flags, root_mount_data);
switch (err) {
case 0:
goto out;
case -EACCES:
case -EINVAL:
#ifdef CONFIG_BLOCK
init_flush_fput();
#endif
continue;
}
/*
* Allow the user to distinguish between failed sys_open
* and bad superblock on root device.
* and give them a list of the available devices
*/
printk("VFS: Cannot open root device \"%s\" or %s: error %d\n",
pretty_name, b, err);
printk("Please append a correct \"root=\" boot option; here are the available partitions:\n");
printk_all_partitions();
if (root_fs_names)
num_fs = list_bdev_fs_names(fs_names, PAGE_SIZE);
if (!num_fs)
pr_err("Can't find any bdev filesystem to be used for mount!\n");
else {
pr_err("List of all bdev filesystems:\n");
for (i = 0, p = fs_names; i < num_fs; i++, p += strlen(p)+1)
pr_err(" %s", p);
pr_err("\n");
}
panic("VFS: Unable to mount root fs on %s", b);
}
if (!(flags & SB_RDONLY)) {
flags |= SB_RDONLY;
goto retry;
}
printk("List of all partitions:\n");
printk_all_partitions();
printk("No filesystem could mount root, tried: ");
for (i = 0, p = fs_names; i < num_fs; i++, p += strlen(p)+1)
printk(" %s", p);
printk("\n");
panic("VFS: Unable to mount root fs on \"%s\" or %s", pretty_name, b);
out:
put_page(page);
}
#ifdef CONFIG_ROOT_NFS
#define NFSROOT_TIMEOUT_MIN 5
#define NFSROOT_TIMEOUT_MAX 30
#define NFSROOT_RETRY_MAX 5
static void __init mount_nfs_root(void)
{
char *root_dev, *root_data;
unsigned int timeout;
int try;
if (nfs_root_data(&root_dev, &root_data))
goto fail;
/*
* The server or network may not be ready, so try several
* times. Stop after a few tries in case the client wants
* to fall back to other boot methods.
*/
timeout = NFSROOT_TIMEOUT_MIN;
for (try = 1; ; try++) {
if (!do_mount_root(root_dev, "nfs", root_mountflags, root_data))
return;
if (try > NFSROOT_RETRY_MAX)
break;
/* Wait, in case the server refused us immediately */
ssleep(timeout);
timeout <<= 1;
if (timeout > NFSROOT_TIMEOUT_MAX)
timeout = NFSROOT_TIMEOUT_MAX;
}
fail:
pr_err("VFS: Unable to mount root fs via NFS.\n");
}
#else
static inline void mount_nfs_root(void)
{
}
#endif /* CONFIG_ROOT_NFS */
#ifdef CONFIG_CIFS_ROOT
#define CIFSROOT_TIMEOUT_MIN 5
#define CIFSROOT_TIMEOUT_MAX 30
#define CIFSROOT_RETRY_MAX 5
static void __init mount_cifs_root(void)
{
char *root_dev, *root_data;
unsigned int timeout;
int try;
if (cifs_root_data(&root_dev, &root_data))
goto fail;
timeout = CIFSROOT_TIMEOUT_MIN;
for (try = 1; ; try++) {
if (!do_mount_root(root_dev, "cifs", root_mountflags,
root_data))
return;
if (try > CIFSROOT_RETRY_MAX)
break;
ssleep(timeout);
timeout <<= 1;
if (timeout > CIFSROOT_TIMEOUT_MAX)
timeout = CIFSROOT_TIMEOUT_MAX;
}
fail:
pr_err("VFS: Unable to mount root fs via SMB.\n");
}
#else
static inline void mount_cifs_root(void)
{
}
#endif /* CONFIG_CIFS_ROOT */
static bool __init fs_is_nodev(char *fstype)
{
struct file_system_type *fs = get_fs_type(fstype);
bool ret = false;
if (fs) {
ret = !(fs->fs_flags & FS_REQUIRES_DEV);
put_filesystem(fs);
}
return ret;
}
static int __init mount_nodev_root(char *root_device_name)
{
char *fs_names, *fstype;
int err = -EINVAL;
int num_fs, i;
fs_names = (void *)__get_free_page(GFP_KERNEL);
if (!fs_names)
return -EINVAL;
num_fs = split_fs_names(fs_names, PAGE_SIZE);
for (i = 0, fstype = fs_names; i < num_fs;
i++, fstype += strlen(fstype) + 1) {
if (!*fstype)
continue;
if (!fs_is_nodev(fstype))
continue;
err = do_mount_root(root_device_name, fstype, root_mountflags,
root_mount_data);
if (!err)
break;
}
free_page((unsigned long)fs_names);
return err;
}
#ifdef CONFIG_BLOCK
static void __init mount_block_root(char *root_device_name)
{
int err = create_dev("/dev/root", ROOT_DEV);
if (err < 0)
pr_emerg("Failed to create /dev/root: %d\n", err);
mount_root_generic("/dev/root", root_device_name, root_mountflags);
}
#else
static inline void mount_block_root(char *root_device_name)
{
}
#endif /* CONFIG_BLOCK */
void __init mount_root(char *root_device_name)
{
switch (ROOT_DEV) {
case Root_NFS:
mount_nfs_root();
break;
case Root_CIFS:
mount_cifs_root();
break;
case Root_Generic:
mount_root_generic(root_device_name, root_device_name,
root_mountflags);
break;
case 0:
if (root_device_name && root_fs_names &&
mount_nodev_root(root_device_name) == 0)
break;
fallthrough;
default:
mount_block_root(root_device_name);
break;
}
}
/* wait for any asynchronous scanning to complete */
static void __init wait_for_root(char *root_device_name)
{
ktime_t end;
if (ROOT_DEV != 0)
return;
pr_info("Waiting for root device %s...\n", root_device_name);
end = ktime_add_ms(ktime_get_raw(), root_wait);
while (!driver_probe_done() ||
early_lookup_bdev(root_device_name, &ROOT_DEV) < 0) {
msleep(5);
if (root_wait > 0 && ktime_after(ktime_get_raw(), end))
break;
}
async_synchronize_full();
}
static dev_t __init parse_root_device(char *root_device_name)
{
int error;
dev_t dev;
if (!strncmp(root_device_name, "mtd", 3) ||
!strncmp(root_device_name, "ubi", 3))
return Root_Generic;
if (strcmp(root_device_name, "/dev/nfs") == 0)
return Root_NFS;
if (strcmp(root_device_name, "/dev/cifs") == 0)
return Root_CIFS;
if (strcmp(root_device_name, "/dev/ram") == 0)
return Root_RAM0;
error = early_lookup_bdev(root_device_name, &dev);
if (error) {
if (error == -EINVAL && root_wait) {
pr_err("Disabling rootwait; root= is invalid.\n");
root_wait = 0;
}
return 0;
}
return dev;
}
/*
* Prepare the namespace - decide what/where to mount, load ramdisks, etc.
*/
void __init prepare_namespace(void)
{
if (root_delay) {
printk(KERN_INFO "Waiting %d sec before mounting root device...\n",
root_delay);
ssleep(root_delay);
}
/*
* wait for the known devices to complete their probing
*
* Note: this is a potential source of long boot delays.
* For example, it is not atypical to wait 5 seconds here
* for the touchpad of a laptop to initialize.
*/
wait_for_device_probe();
md_run_setup();
if (saved_root_name[0])
ROOT_DEV = parse_root_device(saved_root_name);
if (initrd_load(saved_root_name))
goto out;
if (root_wait)
wait_for_root(saved_root_name);
mount_root(saved_root_name);
out:
devtmpfs_mount();
init_mount(".", "/", NULL, MS_MOVE, NULL);
init_chroot(".");
}
static bool is_tmpfs;
static int rootfs_init_fs_context(struct fs_context *fc)
{
if (IS_ENABLED(CONFIG_TMPFS) && is_tmpfs)
return shmem_init_fs_context(fc);
return ramfs_init_fs_context(fc);
}
struct file_system_type rootfs_fs_type = {
.name = "rootfs",
.init_fs_context = rootfs_init_fs_context,
.kill_sb = kill_litter_super,
};
void __init init_rootfs(void)
{
if (IS_ENABLED(CONFIG_TMPFS)) {
if (!saved_root_name[0] && !root_fs_names)
is_tmpfs = true;
else if (root_fs_names && !!strstr(root_fs_names, "tmpfs"))
is_tmpfs = true;
}
}