linux-stable/init/initramfs.c
Rasmus Villemoes b234ed6d62 init: move usermodehelper_enable() to populate_rootfs()
Currently, usermodehelper is enabled right before PID1 starts going
through the initcalls. However, any call of a usermodehelper from a
pure_, core_, postcore_, arch_, subsys_ or fs_ initcall is futile, as
there is no filesystem contents yet.

Up until commit e7cb072eb9 ("init/initramfs.c: do unpacking
asynchronously"), such calls, whether via some request_module(), a
legacy uevent "/sbin/hotplug" notification or something else, would
just fail silently with (presumably) -ENOENT from
kernel_execve(). However, that commit introduced the
wait_for_initramfs() synchronization hook which must be called from
the usermodehelper exec path right before the kernel_execve, in order
that request_module() et al done from *after* rootfs_initcall()
time (i.e. device_ and late_ initcalls) would continue to find a
populated initramfs as they used to.

Any call of wait_for_initramfs() done before the unpacking has been
scheduled (i.e. before rootfs_initcall time) must just return
immediately [and let the caller find an empty file system] in order
not to deadlock the machine. I mistakenly thought, and my limited
testing confirmed, that there were no such calls, so I added a
pr_warn_once() in wait_for_initramfs(). It turns out that one can
indeed hit request_module() as well as kobject_uevent_env() during
those early init calls, leading to a user-visible warning in the
kernel log emitted consistently for certain configurations.

We could just remove the pr_warn_once(), but I think it's better to
postpone enabling the usermodehelper framework until there is at least
some chance of finding the executable. That is also a little more
efficient in that a lot of work done in umh.c will be elided. However,
it does change the error seen by those early callers from -ENOENT to
-EBUSY, so there is a risk of a regression if any caller care about
the exact error value.

Link: https://lkml.kernel.org/r/20210728134638.329060-1-linux@rasmusvillemoes.dk
Fixes: e7cb072eb9 ("init/initramfs.c: do unpacking asynchronously")
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reported-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Reported-by: Bruno Goncalves <bgoncalv@redhat.com>
Reported-by: Heiner Kallweit <hkallweit1@gmail.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-08 11:50:27 -07:00

736 lines
16 KiB
C

// SPDX-License-Identifier: GPL-2.0
#include <linux/init.h>
#include <linux/async.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/fcntl.h>
#include <linux/delay.h>
#include <linux/string.h>
#include <linux/dirent.h>
#include <linux/syscalls.h>
#include <linux/utime.h>
#include <linux/file.h>
#include <linux/memblock.h>
#include <linux/mm.h>
#include <linux/namei.h>
#include <linux/init_syscalls.h>
#include <linux/umh.h>
static ssize_t __init xwrite(struct file *file, const char *p, size_t count,
loff_t *pos)
{
ssize_t out = 0;
/* sys_write only can write MAX_RW_COUNT aka 2G-4K bytes at most */
while (count) {
ssize_t rv = kernel_write(file, p, count, pos);
if (rv < 0) {
if (rv == -EINTR || rv == -EAGAIN)
continue;
return out ? out : rv;
} else if (rv == 0)
break;
p += rv;
out += rv;
count -= rv;
}
return out;
}
static __initdata char *message;
static void __init error(char *x)
{
if (!message)
message = x;
}
static void panic_show_mem(const char *fmt, ...)
{
va_list args;
show_mem(0, NULL);
va_start(args, fmt);
panic(fmt, args);
va_end(args);
}
/* link hash */
#define N_ALIGN(len) ((((len) + 1) & ~3) + 2)
static __initdata struct hash {
int ino, minor, major;
umode_t mode;
struct hash *next;
char name[N_ALIGN(PATH_MAX)];
} *head[32];
static inline int hash(int major, int minor, int ino)
{
unsigned long tmp = ino + minor + (major << 3);
tmp += tmp >> 5;
return tmp & 31;
}
static char __init *find_link(int major, int minor, int ino,
umode_t mode, char *name)
{
struct hash **p, *q;
for (p = head + hash(major, minor, ino); *p; p = &(*p)->next) {
if ((*p)->ino != ino)
continue;
if ((*p)->minor != minor)
continue;
if ((*p)->major != major)
continue;
if (((*p)->mode ^ mode) & S_IFMT)
continue;
return (*p)->name;
}
q = kmalloc(sizeof(struct hash), GFP_KERNEL);
if (!q)
panic_show_mem("can't allocate link hash entry");
q->major = major;
q->minor = minor;
q->ino = ino;
q->mode = mode;
strcpy(q->name, name);
q->next = NULL;
*p = q;
return NULL;
}
static void __init free_hash(void)
{
struct hash **p, *q;
for (p = head; p < head + 32; p++) {
while (*p) {
q = *p;
*p = q->next;
kfree(q);
}
}
}
static long __init do_utime(char *filename, time64_t mtime)
{
struct timespec64 t[2];
t[0].tv_sec = mtime;
t[0].tv_nsec = 0;
t[1].tv_sec = mtime;
t[1].tv_nsec = 0;
return init_utimes(filename, t);
}
static __initdata LIST_HEAD(dir_list);
struct dir_entry {
struct list_head list;
char *name;
time64_t mtime;
};
static void __init dir_add(const char *name, time64_t mtime)
{
struct dir_entry *de = kmalloc(sizeof(struct dir_entry), GFP_KERNEL);
if (!de)
panic_show_mem("can't allocate dir_entry buffer");
INIT_LIST_HEAD(&de->list);
de->name = kstrdup(name, GFP_KERNEL);
de->mtime = mtime;
list_add(&de->list, &dir_list);
}
static void __init dir_utime(void)
{
struct dir_entry *de, *tmp;
list_for_each_entry_safe(de, tmp, &dir_list, list) {
list_del(&de->list);
do_utime(de->name, de->mtime);
kfree(de->name);
kfree(de);
}
}
static __initdata time64_t mtime;
/* cpio header parsing */
static __initdata unsigned long ino, major, minor, nlink;
static __initdata umode_t mode;
static __initdata unsigned long body_len, name_len;
static __initdata uid_t uid;
static __initdata gid_t gid;
static __initdata unsigned rdev;
static void __init parse_header(char *s)
{
unsigned long parsed[12];
char buf[9];
int i;
buf[8] = '\0';
for (i = 0, s += 6; i < 12; i++, s += 8) {
memcpy(buf, s, 8);
parsed[i] = simple_strtoul(buf, NULL, 16);
}
ino = parsed[0];
mode = parsed[1];
uid = parsed[2];
gid = parsed[3];
nlink = parsed[4];
mtime = parsed[5]; /* breaks in y2106 */
body_len = parsed[6];
major = parsed[7];
minor = parsed[8];
rdev = new_encode_dev(MKDEV(parsed[9], parsed[10]));
name_len = parsed[11];
}
/* FSM */
static __initdata enum state {
Start,
Collect,
GotHeader,
SkipIt,
GotName,
CopyFile,
GotSymlink,
Reset
} state, next_state;
static __initdata char *victim;
static unsigned long byte_count __initdata;
static __initdata loff_t this_header, next_header;
static inline void __init eat(unsigned n)
{
victim += n;
this_header += n;
byte_count -= n;
}
static __initdata char *collected;
static long remains __initdata;
static __initdata char *collect;
static void __init read_into(char *buf, unsigned size, enum state next)
{
if (byte_count >= size) {
collected = victim;
eat(size);
state = next;
} else {
collect = collected = buf;
remains = size;
next_state = next;
state = Collect;
}
}
static __initdata char *header_buf, *symlink_buf, *name_buf;
static int __init do_start(void)
{
read_into(header_buf, 110, GotHeader);
return 0;
}
static int __init do_collect(void)
{
unsigned long n = remains;
if (byte_count < n)
n = byte_count;
memcpy(collect, victim, n);
eat(n);
collect += n;
if ((remains -= n) != 0)
return 1;
state = next_state;
return 0;
}
static int __init do_header(void)
{
if (memcmp(collected, "070707", 6)==0) {
error("incorrect cpio method used: use -H newc option");
return 1;
}
if (memcmp(collected, "070701", 6)) {
error("no cpio magic");
return 1;
}
parse_header(collected);
next_header = this_header + N_ALIGN(name_len) + body_len;
next_header = (next_header + 3) & ~3;
state = SkipIt;
if (name_len <= 0 || name_len > PATH_MAX)
return 0;
if (S_ISLNK(mode)) {
if (body_len > PATH_MAX)
return 0;
collect = collected = symlink_buf;
remains = N_ALIGN(name_len) + body_len;
next_state = GotSymlink;
state = Collect;
return 0;
}
if (S_ISREG(mode) || !body_len)
read_into(name_buf, N_ALIGN(name_len), GotName);
return 0;
}
static int __init do_skip(void)
{
if (this_header + byte_count < next_header) {
eat(byte_count);
return 1;
} else {
eat(next_header - this_header);
state = next_state;
return 0;
}
}
static int __init do_reset(void)
{
while (byte_count && *victim == '\0')
eat(1);
if (byte_count && (this_header & 3))
error("broken padding");
return 1;
}
static void __init clean_path(char *path, umode_t fmode)
{
struct kstat st;
if (!init_stat(path, &st, AT_SYMLINK_NOFOLLOW) &&
(st.mode ^ fmode) & S_IFMT) {
if (S_ISDIR(st.mode))
init_rmdir(path);
else
init_unlink(path);
}
}
static int __init maybe_link(void)
{
if (nlink >= 2) {
char *old = find_link(major, minor, ino, mode, collected);
if (old) {
clean_path(collected, 0);
return (init_link(old, collected) < 0) ? -1 : 1;
}
}
return 0;
}
static __initdata struct file *wfile;
static __initdata loff_t wfile_pos;
static int __init do_name(void)
{
state = SkipIt;
next_state = Reset;
if (strcmp(collected, "TRAILER!!!") == 0) {
free_hash();
return 0;
}
clean_path(collected, mode);
if (S_ISREG(mode)) {
int ml = maybe_link();
if (ml >= 0) {
int openflags = O_WRONLY|O_CREAT;
if (ml != 1)
openflags |= O_TRUNC;
wfile = filp_open(collected, openflags, mode);
if (IS_ERR(wfile))
return 0;
wfile_pos = 0;
vfs_fchown(wfile, uid, gid);
vfs_fchmod(wfile, mode);
if (body_len)
vfs_truncate(&wfile->f_path, body_len);
state = CopyFile;
}
} else if (S_ISDIR(mode)) {
init_mkdir(collected, mode);
init_chown(collected, uid, gid, 0);
init_chmod(collected, mode);
dir_add(collected, mtime);
} else if (S_ISBLK(mode) || S_ISCHR(mode) ||
S_ISFIFO(mode) || S_ISSOCK(mode)) {
if (maybe_link() == 0) {
init_mknod(collected, mode, rdev);
init_chown(collected, uid, gid, 0);
init_chmod(collected, mode);
do_utime(collected, mtime);
}
}
return 0;
}
static int __init do_copy(void)
{
if (byte_count >= body_len) {
struct timespec64 t[2] = { };
if (xwrite(wfile, victim, body_len, &wfile_pos) != body_len)
error("write error");
t[0].tv_sec = mtime;
t[1].tv_sec = mtime;
vfs_utimes(&wfile->f_path, t);
fput(wfile);
eat(body_len);
state = SkipIt;
return 0;
} else {
if (xwrite(wfile, victim, byte_count, &wfile_pos) != byte_count)
error("write error");
body_len -= byte_count;
eat(byte_count);
return 1;
}
}
static int __init do_symlink(void)
{
collected[N_ALIGN(name_len) + body_len] = '\0';
clean_path(collected, 0);
init_symlink(collected + N_ALIGN(name_len), collected);
init_chown(collected, uid, gid, AT_SYMLINK_NOFOLLOW);
do_utime(collected, mtime);
state = SkipIt;
next_state = Reset;
return 0;
}
static __initdata int (*actions[])(void) = {
[Start] = do_start,
[Collect] = do_collect,
[GotHeader] = do_header,
[SkipIt] = do_skip,
[GotName] = do_name,
[CopyFile] = do_copy,
[GotSymlink] = do_symlink,
[Reset] = do_reset,
};
static long __init write_buffer(char *buf, unsigned long len)
{
byte_count = len;
victim = buf;
while (!actions[state]())
;
return len - byte_count;
}
static long __init flush_buffer(void *bufv, unsigned long len)
{
char *buf = (char *) bufv;
long written;
long origLen = len;
if (message)
return -1;
while ((written = write_buffer(buf, len)) < len && !message) {
char c = buf[written];
if (c == '0') {
buf += written;
len -= written;
state = Start;
} else if (c == 0) {
buf += written;
len -= written;
state = Reset;
} else
error("junk within compressed archive");
}
return origLen;
}
static unsigned long my_inptr; /* index of next byte to be processed in inbuf */
#include <linux/decompress/generic.h>
static char * __init unpack_to_rootfs(char *buf, unsigned long len)
{
long written;
decompress_fn decompress;
const char *compress_name;
static __initdata char msg_buf[64];
header_buf = kmalloc(110, GFP_KERNEL);
symlink_buf = kmalloc(PATH_MAX + N_ALIGN(PATH_MAX) + 1, GFP_KERNEL);
name_buf = kmalloc(N_ALIGN(PATH_MAX), GFP_KERNEL);
if (!header_buf || !symlink_buf || !name_buf)
panic_show_mem("can't allocate buffers");
state = Start;
this_header = 0;
message = NULL;
while (!message && len) {
loff_t saved_offset = this_header;
if (*buf == '0' && !(this_header & 3)) {
state = Start;
written = write_buffer(buf, len);
buf += written;
len -= written;
continue;
}
if (!*buf) {
buf++;
len--;
this_header++;
continue;
}
this_header = 0;
decompress = decompress_method(buf, len, &compress_name);
pr_debug("Detected %s compressed data\n", compress_name);
if (decompress) {
int res = decompress(buf, len, NULL, flush_buffer, NULL,
&my_inptr, error);
if (res)
error("decompressor failed");
} else if (compress_name) {
if (!message) {
snprintf(msg_buf, sizeof msg_buf,
"compression method %s not configured",
compress_name);
message = msg_buf;
}
} else
error("invalid magic at start of compressed archive");
if (state != Reset)
error("junk at the end of compressed archive");
this_header = saved_offset + my_inptr;
buf += my_inptr;
len -= my_inptr;
}
dir_utime();
kfree(name_buf);
kfree(symlink_buf);
kfree(header_buf);
return message;
}
static int __initdata do_retain_initrd;
static int __init retain_initrd_param(char *str)
{
if (*str)
return 0;
do_retain_initrd = 1;
return 1;
}
__setup("retain_initrd", retain_initrd_param);
#ifdef CONFIG_ARCH_HAS_KEEPINITRD
static int __init keepinitrd_setup(char *__unused)
{
do_retain_initrd = 1;
return 1;
}
__setup("keepinitrd", keepinitrd_setup);
#endif
static bool __initdata initramfs_async = true;
static int __init initramfs_async_setup(char *str)
{
strtobool(str, &initramfs_async);
return 1;
}
__setup("initramfs_async=", initramfs_async_setup);
extern char __initramfs_start[];
extern unsigned long __initramfs_size;
#include <linux/initrd.h>
#include <linux/kexec.h>
void __init reserve_initrd_mem(void)
{
phys_addr_t start;
unsigned long size;
/* Ignore the virtul address computed during device tree parsing */
initrd_start = initrd_end = 0;
if (!phys_initrd_size)
return;
/*
* Round the memory region to page boundaries as per free_initrd_mem()
* This allows us to detect whether the pages overlapping the initrd
* are in use, but more importantly, reserves the entire set of pages
* as we don't want these pages allocated for other purposes.
*/
start = round_down(phys_initrd_start, PAGE_SIZE);
size = phys_initrd_size + (phys_initrd_start - start);
size = round_up(size, PAGE_SIZE);
if (!memblock_is_region_memory(start, size)) {
pr_err("INITRD: 0x%08llx+0x%08lx is not a memory region",
(u64)start, size);
goto disable;
}
if (memblock_is_region_reserved(start, size)) {
pr_err("INITRD: 0x%08llx+0x%08lx overlaps in-use memory region\n",
(u64)start, size);
goto disable;
}
memblock_reserve(start, size);
/* Now convert initrd to virtual addresses */
initrd_start = (unsigned long)__va(phys_initrd_start);
initrd_end = initrd_start + phys_initrd_size;
initrd_below_start_ok = 1;
return;
disable:
pr_cont(" - disabling initrd\n");
initrd_start = 0;
initrd_end = 0;
}
void __weak __init free_initrd_mem(unsigned long start, unsigned long end)
{
#ifdef CONFIG_ARCH_KEEP_MEMBLOCK
unsigned long aligned_start = ALIGN_DOWN(start, PAGE_SIZE);
unsigned long aligned_end = ALIGN(end, PAGE_SIZE);
memblock_free(__pa(aligned_start), aligned_end - aligned_start);
#endif
free_reserved_area((void *)start, (void *)end, POISON_FREE_INITMEM,
"initrd");
}
#ifdef CONFIG_KEXEC_CORE
static bool __init kexec_free_initrd(void)
{
unsigned long crashk_start = (unsigned long)__va(crashk_res.start);
unsigned long crashk_end = (unsigned long)__va(crashk_res.end);
/*
* If the initrd region is overlapped with crashkernel reserved region,
* free only memory that is not part of crashkernel region.
*/
if (initrd_start >= crashk_end || initrd_end <= crashk_start)
return false;
/*
* Initialize initrd memory region since the kexec boot does not do.
*/
memset((void *)initrd_start, 0, initrd_end - initrd_start);
if (initrd_start < crashk_start)
free_initrd_mem(initrd_start, crashk_start);
if (initrd_end > crashk_end)
free_initrd_mem(crashk_end, initrd_end);
return true;
}
#else
static inline bool kexec_free_initrd(void)
{
return false;
}
#endif /* CONFIG_KEXEC_CORE */
#ifdef CONFIG_BLK_DEV_RAM
static void __init populate_initrd_image(char *err)
{
ssize_t written;
struct file *file;
loff_t pos = 0;
unpack_to_rootfs(__initramfs_start, __initramfs_size);
printk(KERN_INFO "rootfs image is not initramfs (%s); looks like an initrd\n",
err);
file = filp_open("/initrd.image", O_WRONLY | O_CREAT, 0700);
if (IS_ERR(file))
return;
written = xwrite(file, (char *)initrd_start, initrd_end - initrd_start,
&pos);
if (written != initrd_end - initrd_start)
pr_err("/initrd.image: incomplete write (%zd != %ld)\n",
written, initrd_end - initrd_start);
fput(file);
}
#endif /* CONFIG_BLK_DEV_RAM */
static void __init do_populate_rootfs(void *unused, async_cookie_t cookie)
{
/* Load the built in initramfs */
char *err = unpack_to_rootfs(__initramfs_start, __initramfs_size);
if (err)
panic_show_mem("%s", err); /* Failed to decompress INTERNAL initramfs */
if (!initrd_start || IS_ENABLED(CONFIG_INITRAMFS_FORCE))
goto done;
if (IS_ENABLED(CONFIG_BLK_DEV_RAM))
printk(KERN_INFO "Trying to unpack rootfs image as initramfs...\n");
else
printk(KERN_INFO "Unpacking initramfs...\n");
err = unpack_to_rootfs((char *)initrd_start, initrd_end - initrd_start);
if (err) {
#ifdef CONFIG_BLK_DEV_RAM
populate_initrd_image(err);
#else
printk(KERN_EMERG "Initramfs unpacking failed: %s\n", err);
#endif
}
done:
/*
* If the initrd region is overlapped with crashkernel reserved region,
* free only memory that is not part of crashkernel region.
*/
if (!do_retain_initrd && initrd_start && !kexec_free_initrd())
free_initrd_mem(initrd_start, initrd_end);
initrd_start = 0;
initrd_end = 0;
flush_delayed_fput();
}
static ASYNC_DOMAIN_EXCLUSIVE(initramfs_domain);
static async_cookie_t initramfs_cookie;
void wait_for_initramfs(void)
{
if (!initramfs_cookie) {
/*
* Something before rootfs_initcall wants to access
* the filesystem/initramfs. Probably a bug. Make a
* note, avoid deadlocking the machine, and let the
* caller's access fail as it used to.
*/
pr_warn_once("wait_for_initramfs() called before rootfs_initcalls\n");
return;
}
async_synchronize_cookie_domain(initramfs_cookie + 1, &initramfs_domain);
}
EXPORT_SYMBOL_GPL(wait_for_initramfs);
static int __init populate_rootfs(void)
{
initramfs_cookie = async_schedule_domain(do_populate_rootfs, NULL,
&initramfs_domain);
usermodehelper_enable();
if (!initramfs_async)
wait_for_initramfs();
return 0;
}
rootfs_initcall(populate_rootfs);