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acrn-kernel/init/do_mounts.c

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// 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/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 root_device_name;
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);
#ifdef CONFIG_BLOCK
struct uuidcmp {
const char *uuid;
int len;
};
/**
* match_dev_by_uuid - callback for finding a partition using its uuid
* @dev: device passed in by the caller
* @data: opaque pointer to the desired struct uuidcmp to match
*
* Returns 1 if the device matches, and 0 otherwise.
*/
static int match_dev_by_uuid(struct device *dev, const void *data)
{
struct block_device *bdev = dev_to_bdev(dev);
const struct uuidcmp *cmp = data;
if (!bdev->bd_meta_info ||
strncasecmp(cmp->uuid, bdev->bd_meta_info->uuid, cmp->len))
return 0;
return 1;
}
/**
* devt_from_partuuid - looks up the dev_t of a partition by its UUID
* @uuid_str: char array containing ascii UUID
*
* The function will return the first partition which contains a matching
* UUID value in its partition_meta_info struct. This does not search
* by filesystem UUIDs.
*
* If @uuid_str is followed by a "/PARTNROFF=%d", then the number will be
* extracted and used as an offset from the partition identified by the UUID.
*
* Returns the matching dev_t on success or 0 on failure.
*/
static dev_t devt_from_partuuid(const char *uuid_str)
{
struct uuidcmp cmp;
struct device *dev = NULL;
dev_t devt = 0;
int offset = 0;
char *slash;
cmp.uuid = uuid_str;
slash = strchr(uuid_str, '/');
/* Check for optional partition number offset attributes. */
if (slash) {
char c = 0;
/* Explicitly fail on poor PARTUUID syntax. */
if (sscanf(slash + 1, "PARTNROFF=%d%c", &offset, &c) != 1)
goto clear_root_wait;
cmp.len = slash - uuid_str;
} else {
cmp.len = strlen(uuid_str);
}
if (!cmp.len)
goto clear_root_wait;
dev = class_find_device(&block_class, NULL, &cmp, &match_dev_by_uuid);
if (!dev)
return 0;
if (offset) {
/*
* Attempt to find the requested partition by adding an offset
* to the partition number found by UUID.
*/
devt = part_devt(dev_to_disk(dev),
dev_to_bdev(dev)->bd_partno + offset);
} else {
devt = dev->devt;
}
put_device(dev);
return devt;
clear_root_wait:
pr_err("VFS: PARTUUID= is invalid.\n"
"Expected PARTUUID=<valid-uuid-id>[/PARTNROFF=%%d]\n");
if (root_wait)
pr_err("Disabling rootwait; root= is invalid.\n");
root_wait = 0;
return 0;
}
/**
* match_dev_by_label - callback for finding a partition using its label
* @dev: device passed in by the caller
* @data: opaque pointer to the label to match
*
* Returns 1 if the device matches, and 0 otherwise.
*/
static int match_dev_by_label(struct device *dev, const void *data)
{
struct block_device *bdev = dev_to_bdev(dev);
const char *label = data;
if (!bdev->bd_meta_info || strcmp(label, bdev->bd_meta_info->volname))
return 0;
return 1;
}
static dev_t devt_from_partlabel(const char *label)
{
struct device *dev;
dev_t devt = 0;
dev = class_find_device(&block_class, NULL, label, &match_dev_by_label);
if (dev) {
devt = dev->devt;
put_device(dev);
}
return devt;
}
static dev_t devt_from_devname(const char *name)
{
dev_t devt = 0;
int part;
char s[32];
char *p;
if (strlen(name) > 31)
return 0;
strcpy(s, name);
for (p = s; *p; p++) {
if (*p == '/')
*p = '!';
}
devt = blk_lookup_devt(s, 0);
if (devt)
return devt;
/*
* Try non-existent, but valid partition, which may only exist after
* opening the device, like partitioned md devices.
*/
while (p > s && isdigit(p[-1]))
p--;
if (p == s || !*p || *p == '0')
return 0;
/* try disk name without <part number> */
part = simple_strtoul(p, NULL, 10);
*p = '\0';
devt = blk_lookup_devt(s, part);
if (devt)
return devt;
/* try disk name without p<part number> */
if (p < s + 2 || !isdigit(p[-2]) || p[-1] != 'p')
return 0;
p[-1] = '\0';
return blk_lookup_devt(s, part);
}
#endif /* CONFIG_BLOCK */
static dev_t devt_from_devnum(const char *name)
{
unsigned maj, min, offset;
dev_t devt = 0;
char *p, dummy;
if (sscanf(name, "%u:%u%c", &maj, &min, &dummy) == 2 ||
sscanf(name, "%u:%u:%u:%c", &maj, &min, &offset, &dummy) == 3) {
devt = MKDEV(maj, min);
if (maj != MAJOR(devt) || min != MINOR(devt))
return 0;
} else {
devt = new_decode_dev(simple_strtoul(name, &p, 16));
if (*p)
return 0;
}
return devt;
}
/*
* Convert a name into device number. We accept the following variants:
*
* 1) <hex_major><hex_minor> device number in hexadecimal represents itself
* no leading 0x, for example b302.
* 2) /dev/nfs represents Root_NFS (0xff)
* 3) /dev/<disk_name> represents the device number of disk
* 4) /dev/<disk_name><decimal> represents the device number
* of partition - device number of disk plus the partition number
* 5) /dev/<disk_name>p<decimal> - same as the above, that form is
* used when disk name of partitioned disk ends on a digit.
* 6) PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF representing the
* unique id of a partition if the partition table provides it.
* The UUID may be either an EFI/GPT UUID, or refer to an MSDOS
* partition using the format SSSSSSSS-PP, where SSSSSSSS is a zero-
* filled hex representation of the 32-bit "NT disk signature", and PP
* is a zero-filled hex representation of the 1-based partition number.
* 7) PARTUUID=<UUID>/PARTNROFF=<int> to select a partition in relation to
* a partition with a known unique id.
* 8) <major>:<minor> major and minor number of the device separated by
* a colon.
* 9) PARTLABEL=<name> with name being the GPT partition label.
* MSDOS partitions do not support labels!
* 10) /dev/cifs represents Root_CIFS (0xfe)
*
* If name doesn't have fall into the categories above, we return (0,0).
* block_class is used to check if something is a disk name. If the disk
* name contains slashes, the device name has them replaced with
* bangs.
*/
dev_t name_to_dev_t(const char *name)
{
if (strcmp(name, "/dev/nfs") == 0)
return Root_NFS;
if (strcmp(name, "/dev/cifs") == 0)
return Root_CIFS;
if (strcmp(name, "/dev/ram") == 0)
return Root_RAM0;
#ifdef CONFIG_BLOCK
if (strncmp(name, "PARTUUID=", 9) == 0)
return devt_from_partuuid(name + 9);
if (strncmp(name, "PARTLABEL=", 10) == 0)
return devt_from_partlabel(name + 10);
if (strncmp(name, "/dev/", 5) == 0)
return devt_from_devname(name + 5);
#endif
return devt_from_devnum(name);
}
EXPORT_SYMBOL_GPL(name_to_dev_t);
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 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, char *names)
{
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);
/* zero-pad. init_mount() will make sure it's terminated */
strncpy(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_block_root(char *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, root_fs_names);
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:
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",
root_device_name, b, err);
printk("Please append a correct \"root=\" boot option; here are the available partitions:\n");
printk_all_partitions();
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", 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 int __init mount_nfs_root(void)
{
char *root_dev, *root_data;
unsigned int timeout;
int try, err;
err = nfs_root_data(&root_dev, &root_data);
if (err != 0)
return 0;
/*
* 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++) {
err = do_mount_root(root_dev, "nfs",
root_mountflags, root_data);
if (err == 0)
return 1;
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;
}
return 0;
}
#endif
#ifdef CONFIG_CIFS_ROOT
extern int cifs_root_data(char **dev, char **opts);
#define CIFSROOT_TIMEOUT_MIN 5
#define CIFSROOT_TIMEOUT_MAX 30
#define CIFSROOT_RETRY_MAX 5
static int __init mount_cifs_root(void)
{
char *root_dev, *root_data;
unsigned int timeout;
int try, err;
err = cifs_root_data(&root_dev, &root_data);
if (err != 0)
return 0;
timeout = CIFSROOT_TIMEOUT_MIN;
for (try = 1; ; try++) {
err = do_mount_root(root_dev, "cifs", root_mountflags,
root_data);
if (err == 0)
return 1;
if (try > CIFSROOT_RETRY_MAX)
break;
ssleep(timeout);
timeout <<= 1;
if (timeout > CIFSROOT_TIMEOUT_MAX)
timeout = CIFSROOT_TIMEOUT_MAX;
}
return 0;
}
#endif
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(void)
{
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, root_fs_names);
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;
}
void __init mount_root(void)
{
#ifdef CONFIG_ROOT_NFS
if (ROOT_DEV == Root_NFS) {
if (!mount_nfs_root())
printk(KERN_ERR "VFS: Unable to mount root fs via NFS.\n");
return;
}
#endif
#ifdef CONFIG_CIFS_ROOT
if (ROOT_DEV == Root_CIFS) {
if (!mount_cifs_root())
printk(KERN_ERR "VFS: Unable to mount root fs via SMB.\n");
return;
}
#endif
if (ROOT_DEV == 0 && root_device_name && root_fs_names) {
if (mount_nodev_root() == 0)
return;
}
#ifdef CONFIG_BLOCK
{
int err = create_dev("/dev/root", ROOT_DEV);
if (err < 0)
pr_emerg("Failed to create /dev/root: %d\n", err);
mount_block_root("/dev/root", root_mountflags);
}
#endif
}
/*
* 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_device_name = saved_root_name;
if (!strncmp(root_device_name, "mtd", 3) ||
!strncmp(root_device_name, "ubi", 3)) {
mount_block_root(root_device_name, root_mountflags);
goto out;
}
ROOT_DEV = name_to_dev_t(root_device_name);
if (strncmp(root_device_name, "/dev/", 5) == 0)
root_device_name += 5;
}
if (initrd_load())
goto out;
/* wait for any asynchronous scanning to complete */
if ((ROOT_DEV == 0) && root_wait) {
printk(KERN_INFO "Waiting for root device %s...\n",
saved_root_name);
while (driver_probe_done() != 0 ||
(ROOT_DEV = name_to_dev_t(saved_root_name)) == 0)
msleep(5);
async_synchronize_full();
}
mount_root();
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) && !saved_root_name[0] &&
(!root_fs_names || strstr(root_fs_names, "tmpfs")))
is_tmpfs = true;
}
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