aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2019-12-15 11:36:12 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2019-12-15 11:36:12 -0800
commit2e6d304515ba9936d85265ad93dddc4c13c17d06 (patch)
tree0aeaf6e255deb791f02e919e670f563e5505c84f
parent510c9788991c58827373bca719d8cffa4d65f846 (diff)
parent8243186f0cc7c57cf9d6a110cd7315c44e3e0be8 (diff)
downloadlinux-stericsson-2e6d304515ba9936d85265ad93dddc4c13c17d06.tar.gz
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()
-rw-r--r--drivers/base/devtmpfs.c6
-rw-r--r--fs/file.c7
-rw-r--r--fs/namespace.c10
-rw-r--r--include/linux/device.h4
-rw-r--r--include/linux/initrd.h2
-rw-r--r--include/linux/syscalls.h3
-rw-r--r--init/do_mounts.c30
-rw-r--r--init/do_mounts_initrd.c11
-rw-r--r--init/main.c31
9 files changed, 63 insertions, 41 deletions
diff --git a/drivers/base/devtmpfs.c b/drivers/base/devtmpfs.c
index 30d0523014e0..6cdbf1531238 100644
--- a/drivers/base/devtmpfs.c
+++ b/drivers/base/devtmpfs.c
@@ -359,7 +359,7 @@ static int handle_remove(const char *nodename, struct device *dev)
* If configured, or requested by the commandline, devtmpfs will be
* auto-mounted after the kernel mounted the root filesystem.
*/
-int devtmpfs_mount(const char *mntdir)
+int devtmpfs_mount(void)
{
int err;
@@ -369,7 +369,7 @@ int devtmpfs_mount(const char *mntdir)
if (!thread)
return 0;
- err = ksys_mount("devtmpfs", mntdir, "devtmpfs", MS_SILENT, NULL);
+ err = do_mount("devtmpfs", "dev", "devtmpfs", MS_SILENT, NULL);
if (err)
printk(KERN_INFO "devtmpfs: error mounting %i\n", err);
else
@@ -394,7 +394,7 @@ static int devtmpfsd(void *p)
*err = ksys_unshare(CLONE_NEWNS);
if (*err)
goto out;
- *err = ksys_mount("devtmpfs", "/", "devtmpfs", MS_SILENT, NULL);
+ *err = do_mount("devtmpfs", "/", "devtmpfs", MS_SILENT, NULL);
if (*err)
goto out;
ksys_chdir("/.."); /* will traverse into overmounted root */
diff --git a/fs/file.c b/fs/file.c
index 3da91a112bab..2f4fcf985079 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -960,7 +960,7 @@ SYSCALL_DEFINE2(dup2, unsigned int, oldfd, unsigned int, newfd)
return ksys_dup3(oldfd, newfd, 0);
}
-int ksys_dup(unsigned int fildes)
+SYSCALL_DEFINE1(dup, unsigned int, fildes)
{
int ret = -EBADF;
struct file *file = fget_raw(fildes);
@@ -975,11 +975,6 @@ int ksys_dup(unsigned int fildes)
return ret;
}
-SYSCALL_DEFINE1(dup, unsigned int, fildes)
-{
- return ksys_dup(fildes);
-}
-
int f_dupfd(unsigned int from, struct file *file, unsigned flags)
{
int err;
diff --git a/fs/namespace.c b/fs/namespace.c
index 2fd0c8bcb8c1..be601d3a8008 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -3325,8 +3325,8 @@ struct dentry *mount_subtree(struct vfsmount *m, const char *name)
}
EXPORT_SYMBOL(mount_subtree);
-int ksys_mount(const char __user *dev_name, const char __user *dir_name,
- const char __user *type, unsigned long flags, void __user *data)
+SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name,
+ char __user *, type, unsigned long, flags, void __user *, data)
{
int ret;
char *kernel_type;
@@ -3359,12 +3359,6 @@ out_type:
return ret;
}
-SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name,
- char __user *, type, unsigned long, flags, void __user *, data)
-{
- return ksys_mount(dev_name, dir_name, type, flags, data);
-}
-
/*
* Create a kernel mount representation for a new, prepared superblock
* (specified by fs_fd) and attach to an open_tree-like file descriptor.
diff --git a/include/linux/device.h b/include/linux/device.h
index e226030c1df3..96ff76731e93 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -1666,11 +1666,11 @@ extern bool kill_device(struct device *dev);
#ifdef CONFIG_DEVTMPFS
extern int devtmpfs_create_node(struct device *dev);
extern int devtmpfs_delete_node(struct device *dev);
-extern int devtmpfs_mount(const char *mntdir);
+extern int devtmpfs_mount(void);
#else
static inline int devtmpfs_create_node(struct device *dev) { return 0; }
static inline int devtmpfs_delete_node(struct device *dev) { return 0; }
-static inline int devtmpfs_mount(const char *mountpoint) { return 0; }
+static inline int devtmpfs_mount(void) { return 0; }
#endif
/* drivers/base/power/shutdown.c */
diff --git a/include/linux/initrd.h b/include/linux/initrd.h
index d77fe34fb00a..aa5914355728 100644
--- a/include/linux/initrd.h
+++ b/include/linux/initrd.h
@@ -28,3 +28,5 @@ extern unsigned int real_root_dev;
extern char __initramfs_start[];
extern unsigned long __initramfs_size;
+
+void console_on_rootfs(void);
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index d0391cc2dae9..2960dedcfde8 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -1231,10 +1231,7 @@ asmlinkage long sys_ni_syscall(void);
* the ksys_xyzyyz() functions prototyped below.
*/
-int ksys_mount(const char __user *dev_name, const char __user *dir_name,
- const char __user *type, unsigned long flags, void __user *data);
int ksys_umount(char __user *name, int flags);
-int ksys_dup(unsigned int fildes);
int ksys_chroot(const char __user *filename);
ssize_t ksys_write(unsigned int fd, const char __user *buf, size_t count);
int ksys_chdir(const char __user *filename);
diff --git a/init/do_mounts.c b/init/do_mounts.c
index af9cda887a23..f55cbd9cb818 100644
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -387,12 +387,25 @@ static void __init get_fs_names(char *page)
*s = '\0';
}
-static int __init do_mount_root(char *name, char *fs, int flags, void *data)
+static int __init do_mount_root(const char *name, const char *fs,
+ const int flags, const void *data)
{
struct super_block *s;
- int err = ksys_mount(name, "/root", fs, flags, data);
- if (err)
- return err;
+ char *data_page;
+ struct page *p;
+ int ret;
+
+ /* do_mount() requires a full page as fifth argument */
+ p = alloc_page(GFP_KERNEL);
+ if (!p)
+ return -ENOMEM;
+
+ data_page = page_address(p);
+ strncpy(data_page, data, PAGE_SIZE - 1);
+
+ ret = do_mount(name, "/root", fs, flags, data_page);
+ if (ret)
+ goto out;
ksys_chdir("/root");
s = current->fs->pwd.dentry->d_sb;
@@ -402,7 +415,10 @@ static int __init do_mount_root(char *name, char *fs, int flags, void *data)
s->s_type->name,
sb_rdonly(s) ? " readonly" : "",
MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
- return 0;
+
+out:
+ put_page(p);
+ return ret;
}
void __init mount_block_root(char *name, int flags)
@@ -670,8 +686,8 @@ void __init prepare_namespace(void)
mount_root();
out:
- devtmpfs_mount("dev");
- ksys_mount(".", "/", NULL, MS_MOVE, NULL);
+ devtmpfs_mount();
+ do_mount(".", "/", NULL, MS_MOVE, NULL);
ksys_chroot(".");
}
diff --git a/init/do_mounts_initrd.c b/init/do_mounts_initrd.c
index a9c6cc56f505..dab8b1151b56 100644
--- a/init/do_mounts_initrd.c
+++ b/init/do_mounts_initrd.c
@@ -48,13 +48,10 @@ early_param("initrd", early_initrd);
static int init_linuxrc(struct subprocess_info *info, struct cred *new)
{
ksys_unshare(CLONE_FS | CLONE_FILES);
- /* stdin/stdout/stderr for /linuxrc */
- ksys_open("/dev/console", O_RDWR, 0);
- ksys_dup(0);
- ksys_dup(0);
+ console_on_rootfs();
/* move initrd over / and chdir/chroot in initrd root */
ksys_chdir("/root");
- ksys_mount(".", "/", NULL, MS_MOVE, NULL);
+ do_mount(".", "/", NULL, MS_MOVE, NULL);
ksys_chroot(".");
ksys_setsid();
return 0;
@@ -89,7 +86,7 @@ static void __init handle_initrd(void)
current->flags &= ~PF_FREEZER_SKIP;
/* move initrd to rootfs' /old */
- ksys_mount("..", ".", NULL, MS_MOVE, NULL);
+ do_mount("..", ".", NULL, MS_MOVE, NULL);
/* switch root and cwd back to / of rootfs */
ksys_chroot("..");
@@ -103,7 +100,7 @@ static void __init handle_initrd(void)
mount_root();
printk(KERN_NOTICE "Trying to move old root to /initrd ... ");
- error = ksys_mount("/old", "/root/initrd", NULL, MS_MOVE, NULL);
+ error = do_mount("/old", "/root/initrd", NULL, MS_MOVE, NULL);
if (!error)
printk("okay\n");
else {
diff --git a/init/main.c b/init/main.c
index 91f6ebb30ef0..ec3a1463ac69 100644
--- a/init/main.c
+++ b/init/main.c
@@ -93,6 +93,7 @@
#include <linux/rodata_test.h>
#include <linux/jump_label.h>
#include <linux/mem_encrypt.h>
+#include <linux/file.h>
#include <asm/io.h>
#include <asm/bugs.h>
@@ -1155,6 +1156,30 @@ static int __ref kernel_init(void *unused)
"See Linux Documentation/admin-guide/init.rst for guidance.");
}
+void console_on_rootfs(void)
+{
+ struct file *file;
+ unsigned int i;
+
+ /* Open /dev/console in kernelspace, this should never fail */
+ file = filp_open("/dev/console", O_RDWR, 0);
+ if (!file)
+ goto err_out;
+
+ /* create stdin/stdout/stderr, this should never fail */
+ for (i = 0; i < 3; i++) {
+ if (f_dupfd(i, file, 0) != i)
+ goto err_out;
+ }
+
+ return;
+
+err_out:
+ /* no panic -- this might not be fatal */
+ pr_err("Warning: unable to open an initial console.\n");
+ return;
+}
+
static noinline void __init kernel_init_freeable(void)
{
/*
@@ -1190,12 +1215,8 @@ static noinline void __init kernel_init_freeable(void)
do_basic_setup();
- /* Open the /dev/console on the rootfs, this should never fail */
- if (ksys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0)
- pr_err("Warning: unable to open an initial console.\n");
+ console_on_rootfs();
- (void) ksys_dup(0);
- (void) ksys_dup(0);
/*
* check if there is an early userspace init. If yes, let it do all
* the work