Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
Merge branch 'remove-ksys-mount-dup' of git://git.kernel.org/pub/scm/linux/kernel/git/brodo/linux
Pull ksys_mount() and ksys_dup() removal from Dominik Brodowski:
"This small series replaces all in-kernel calls to the
userspace-focused ksys_mount() and ksys_dup() with calls to
kernel-centric functions:
For each replacement of ksys_mount() with do_mount(), one needs to
verify that the first and third parameter (char *dev_name, char *type)
are strings allocated in kernelspace and that the fifth parameter
(void *data) is either NULL or refers to a full page (only occurence
in init/do_mounts.c::do_mount_root()). The second and fourth
parameters (char *dir_name, unsigned long flags) are passed by
ksys_mount() to do_mount() unchanged, and therefore do not require
particular care.
Moreover, instead of pretending to be userspace, the opening of
/dev/console as stdin/stdout/stderr can be implemented using in-kernel
functions as well. Thereby, ksys_dup() can be removed for good"
[ This doesn't get rid of the special "kernel init runs with KERNEL_DS"
case, but it at least removes _some_ of the users of "treat kernel
pointers as user pointers for our magical init sequence".
One day we'll hopefully be rid of it all, and can initialize our
init_thread addr_limit to USER_DS. - Linus ]
* 'remove-ksys-mount-dup' of git://git.kernel.org/pub/scm/linux/kernel/git/brodo/linux:
fs: remove ksys_dup()
init: unify opening /dev/console as stdin/stdout/stderr
init: use do_mount() instead of ksys_mount()
initrd: use do_mount() instead of ksys_mount()
devtmpfs: use do_mount() instead of ksys_mount()
+63
-41
+3
-3
drivers/base/devtmpfs.c
+3
-3
drivers/base/devtmpfs.c
···
359
359
* If configured, or requested by the commandline, devtmpfs will be
360
360
* auto-mounted after the kernel mounted the root filesystem.
361
361
*/
362
-
int devtmpfs_mount(const char *mntdir)
362
+
int devtmpfs_mount(void)
363
363
{
364
364
int err;
365
365
···
369
369
if (!thread)
370
370
return 0;
371
371
372
-
err = ksys_mount("devtmpfs", mntdir, "devtmpfs", MS_SILENT, NULL);
372
+
err = do_mount("devtmpfs", "dev", "devtmpfs", MS_SILENT, NULL);
373
373
if (err)
374
374
printk(KERN_INFO "devtmpfs: error mounting %i\n", err);
375
375
else
···
394
394
*err = ksys_unshare(CLONE_NEWNS);
395
395
if (*err)
396
396
goto out;
397
-
*err = ksys_mount("devtmpfs", "/", "devtmpfs", MS_SILENT, NULL);
397
+
*err = do_mount("devtmpfs", "/", "devtmpfs", MS_SILENT, NULL);
398
398
if (*err)
399
399
goto out;
400
400
ksys_chdir("/.."); /* will traverse into overmounted root */
+1
-6
fs/file.c
+1
-6
fs/file.c
···
960
960
return ksys_dup3(oldfd, newfd, 0);
961
961
}
962
962
963
-
int ksys_dup(unsigned int fildes)
963
+
SYSCALL_DEFINE1(dup, unsigned int, fildes)
964
964
{
965
965
int ret = -EBADF;
966
966
struct file *file = fget_raw(fildes);
···
973
973
fput(file);
974
974
}
975
975
return ret;
976
-
}
977
-
978
-
SYSCALL_DEFINE1(dup, unsigned int, fildes)
979
-
{
980
-
return ksys_dup(fildes);
981
976
}
982
977
983
978
int f_dupfd(unsigned int from, struct file *file, unsigned flags)
+2
-8
fs/namespace.c
+2
-8
fs/namespace.c
···
3325
3325
}
3326
3326
EXPORT_SYMBOL(mount_subtree);
3327
3327
3328
-
int ksys_mount(const char __user *dev_name, const char __user *dir_name,
3329
-
const char __user *type, unsigned long flags, void __user *data)
3328
+
SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name,
3329
+
char __user *, type, unsigned long, flags, void __user *, data)
3330
3330
{
3331
3331
int ret;
3332
3332
char *kernel_type;
···
3357
3357
kfree(kernel_type);
3358
3358
out_type:
3359
3359
return ret;
3360
-
}
3361
-
3362
-
SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name,
3363
-
char __user *, type, unsigned long, flags, void __user *, data)
3364
-
{
3365
-
return ksys_mount(dev_name, dir_name, type, flags, data);
3366
3360
}
3367
3361
3368
3362
/*
+2
-2
include/linux/device.h
+2
-2
include/linux/device.h
···
1666
1666
#ifdef CONFIG_DEVTMPFS
1667
1667
extern int devtmpfs_create_node(struct device *dev);
1668
1668
extern int devtmpfs_delete_node(struct device *dev);
1669
-
extern int devtmpfs_mount(const char *mntdir);
1669
+
extern int devtmpfs_mount(void);
1670
1670
#else
1671
1671
static inline int devtmpfs_create_node(struct device *dev) { return 0; }
1672
1672
static inline int devtmpfs_delete_node(struct device *dev) { return 0; }
1673
-
static inline int devtmpfs_mount(const char *mountpoint) { return 0; }
1673
+
static inline int devtmpfs_mount(void) { return 0; }
1674
1674
#endif
1675
1675
1676
1676
/* drivers/base/power/shutdown.c */
+2
include/linux/initrd.h
+2
include/linux/initrd.h
-3
include/linux/syscalls.h
-3
include/linux/syscalls.h
···
1231
1231
* the ksys_xyzyyz() functions prototyped below.
1232
1232
*/
1233
1233
1234
-
int ksys_mount(const char __user *dev_name, const char __user *dir_name,
1235
-
const char __user *type, unsigned long flags, void __user *data);
1236
1234
int ksys_umount(char __user *name, int flags);
1237
-
int ksys_dup(unsigned int fildes);
1238
1235
int ksys_chroot(const char __user *filename);
1239
1236
ssize_t ksys_write(unsigned int fd, const char __user *buf, size_t count);
1240
1237
int ksys_chdir(const char __user *filename);
+23
-7
init/do_mounts.c
+23
-7
init/do_mounts.c
···
387
387
*s = '\0';
388
388
}
389
389
390
-
static int __init do_mount_root(char *name, char *fs, int flags, void *data)
390
+
static int __init do_mount_root(const char *name, const char *fs,
391
+
const int flags, const void *data)
391
392
{
392
393
struct super_block *s;
393
-
int err = ksys_mount(name, "/root", fs, flags, data);
394
-
if (err)
395
-
return err;
394
+
char *data_page;
395
+
struct page *p;
396
+
int ret;
397
+
398
+
/* do_mount() requires a full page as fifth argument */
399
+
p = alloc_page(GFP_KERNEL);
400
+
if (!p)
401
+
return -ENOMEM;
402
+
403
+
data_page = page_address(p);
404
+
strncpy(data_page, data, PAGE_SIZE - 1);
405
+
406
+
ret = do_mount(name, "/root", fs, flags, data_page);
407
+
if (ret)
408
+
goto out;
396
409
397
410
ksys_chdir("/root");
398
411
s = current->fs->pwd.dentry->d_sb;
···
415
402
s->s_type->name,
416
403
sb_rdonly(s) ? " readonly" : "",
417
404
MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
418
-
return 0;
405
+
406
+
out:
407
+
put_page(p);
408
+
return ret;
419
409
}
420
410
421
411
void __init mount_block_root(char *name, int flags)
···
686
670
687
671
mount_root();
688
672
out:
689
-
devtmpfs_mount("dev");
690
-
ksys_mount(".", "/", NULL, MS_MOVE, NULL);
673
+
devtmpfs_mount();
674
+
do_mount(".", "/", NULL, MS_MOVE, NULL);
691
675
ksys_chroot(".");
692
676
}
693
677
+4
-7
init/do_mounts_initrd.c
+4
-7
init/do_mounts_initrd.c
···
48
48
static int init_linuxrc(struct subprocess_info *info, struct cred *new)
49
49
{
50
50
ksys_unshare(CLONE_FS | CLONE_FILES);
51
-
/* stdin/stdout/stderr for /linuxrc */
52
-
ksys_open("/dev/console", O_RDWR, 0);
53
-
ksys_dup(0);
54
-
ksys_dup(0);
51
+
console_on_rootfs();
55
52
/* move initrd over / and chdir/chroot in initrd root */
56
53
ksys_chdir("/root");
57
-
ksys_mount(".", "/", NULL, MS_MOVE, NULL);
54
+
do_mount(".", "/", NULL, MS_MOVE, NULL);
58
55
ksys_chroot(".");
59
56
ksys_setsid();
60
57
return 0;
···
86
89
current->flags &= ~PF_FREEZER_SKIP;
87
90
88
91
/* move initrd to rootfs' /old */
89
-
ksys_mount("..", ".", NULL, MS_MOVE, NULL);
92
+
do_mount("..", ".", NULL, MS_MOVE, NULL);
90
93
/* switch root and cwd back to / of rootfs */
91
94
ksys_chroot("..");
92
95
···
100
103
mount_root();
101
104
102
105
printk(KERN_NOTICE "Trying to move old root to /initrd ... ");
103
-
error = ksys_mount("/old", "/root/initrd", NULL, MS_MOVE, NULL);
106
+
error = do_mount("/old", "/root/initrd", NULL, MS_MOVE, NULL);
104
107
if (!error)
105
108
printk("okay\n");
106
109
else {
+26
-5
init/main.c
+26
-5
init/main.c
···
93
93
#include <linux/rodata_test.h>
94
94
#include <linux/jump_label.h>
95
95
#include <linux/mem_encrypt.h>
96
+
#include <linux/file.h>
96
97
97
98
#include <asm/io.h>
98
99
#include <asm/bugs.h>
···
1156
1155
"See Linux Documentation/admin-guide/init.rst for guidance.");
1157
1156
}
1158
1157
1158
+
void console_on_rootfs(void)
1159
+
{
1160
+
struct file *file;
1161
+
unsigned int i;
1162
+
1163
+
/* Open /dev/console in kernelspace, this should never fail */
1164
+
file = filp_open("/dev/console", O_RDWR, 0);
1165
+
if (!file)
1166
+
goto err_out;
1167
+
1168
+
/* create stdin/stdout/stderr, this should never fail */
1169
+
for (i = 0; i < 3; i++) {
1170
+
if (f_dupfd(i, file, 0) != i)
1171
+
goto err_out;
1172
+
}
1173
+
1174
+
return;
1175
+
1176
+
err_out:
1177
+
/* no panic -- this might not be fatal */
1178
+
pr_err("Warning: unable to open an initial console.\n");
1179
+
return;
1180
+
}
1181
+
1159
1182
static noinline void __init kernel_init_freeable(void)
1160
1183
{
1161
1184
/*
···
1215
1190
1216
1191
do_basic_setup();
1217
1192
1218
-
/* Open the /dev/console on the rootfs, this should never fail */
1219
-
if (ksys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0)
1220
-
pr_err("Warning: unable to open an initial console.\n");
1193
+
console_on_rootfs();
1221
1194
1222
-
(void) ksys_dup(0);
1223
-
(void) ksys_dup(0);
1224
1195
/*
1225
1196
* check if there is an early userspace init. If yes, let it do all
1226
1197
* the work