Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 482 insertions, 0 deletions

diff --git a/drivers/base/devtmpfs.c b/drivers/base/devtmpfs.c
new file mode 100644
index 0000000000..b848764ef0
--- /dev/null
+++ b/drivers/base/devtmpfs.c
@@ -0,0 +1,482 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * devtmpfs - kernel-maintained tmpfs-based /dev
+ *
+ * Copyright (C) 2009, Kay Sievers <kay.sievers@vrfy.org>
+ *
+ * During bootup, before any driver core device is registered,
+ * devtmpfs, a tmpfs-based filesystem is created. Every driver-core
+ * device which requests a device node, will add a node in this
+ * filesystem.
+ * By default, all devices are named after the name of the device,
+ * owned by root and have a default mode of 0600. Subsystems can
+ * overwrite the default setting if needed.
+ */
+
+#define pr_fmt(fmt) "devtmpfs: " fmt
+
+#include <linux/kernel.h>
+#include <linux/syscalls.h>
+#include <linux/mount.h>
+#include <linux/device.h>
+#include <linux/blkdev.h>
+#include <linux/namei.h>
+#include <linux/fs.h>
+#include <linux/shmem_fs.h>
+#include <linux/ramfs.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/kthread.h>
+#include <linux/init_syscalls.h>
+#include <uapi/linux/mount.h>
+#include "base.h"
+
+#ifdef CONFIG_DEVTMPFS_SAFE
+#define DEVTMPFS_MFLAGS       (MS_SILENT | MS_NOEXEC | MS_NOSUID)
+#else
+#define DEVTMPFS_MFLAGS       (MS_SILENT)
+#endif
+
+static struct task_struct *thread;
+
+static int __initdata mount_dev = IS_ENABLED(CONFIG_DEVTMPFS_MOUNT);
+
+static DEFINE_SPINLOCK(req_lock);
+
+static struct req {
+	struct req *next;
+	struct completion done;
+	int err;
+	const char *name;
+	umode_t mode;	/* 0 => delete */
+	kuid_t uid;
+	kgid_t gid;
+	struct device *dev;
+} *requests;
+
+static int __init mount_param(char *str)
+{
+	mount_dev = simple_strtoul(str, NULL, 0);
+	return 1;
+}
+__setup("devtmpfs.mount=", mount_param);
+
+static struct vfsmount *mnt;
+
+static struct dentry *public_dev_mount(struct file_system_type *fs_type, int flags,
+		      const char *dev_name, void *data)
+{
+	struct super_block *s = mnt->mnt_sb;
+	int err;
+
+	atomic_inc(&s->s_active);
+	down_write(&s->s_umount);
+	err = reconfigure_single(s, flags, data);
+	if (err < 0) {
+		deactivate_locked_super(s);
+		return ERR_PTR(err);
+	}
+	return dget(s->s_root);
+}
+
+static struct file_system_type internal_fs_type = {
+	.name = "devtmpfs",
+#ifdef CONFIG_TMPFS
+	.init_fs_context = shmem_init_fs_context,
+#else
+	.init_fs_context = ramfs_init_fs_context,
+#endif
+	.kill_sb = kill_litter_super,
+};
+
+static struct file_system_type dev_fs_type = {
+	.name = "devtmpfs",
+	.mount = public_dev_mount,
+};
+
+static int devtmpfs_submit_req(struct req *req, const char *tmp)
+{
+	init_completion(&req->done);
+
+	spin_lock(&req_lock);
+	req->next = requests;
+	requests = req;
+	spin_unlock(&req_lock);
+
+	wake_up_process(thread);
+	wait_for_completion(&req->done);
+
+	kfree(tmp);
+
+	return req->err;
+}
+
+int devtmpfs_create_node(struct device *dev)
+{
+	const char *tmp = NULL;
+	struct req req;
+
+	if (!thread)
+		return 0;
+
+	req.mode = 0;
+	req.uid = GLOBAL_ROOT_UID;
+	req.gid = GLOBAL_ROOT_GID;
+	req.name = device_get_devnode(dev, &req.mode, &req.uid, &req.gid, &tmp);
+	if (!req.name)
+		return -ENOMEM;
+
+	if (req.mode == 0)
+		req.mode = 0600;
+	if (is_blockdev(dev))
+		req.mode |= S_IFBLK;
+	else
+		req.mode |= S_IFCHR;
+
+	req.dev = dev;
+
+	return devtmpfs_submit_req(&req, tmp);
+}
+
+int devtmpfs_delete_node(struct device *dev)
+{
+	const char *tmp = NULL;
+	struct req req;
+
+	if (!thread)
+		return 0;
+
+	req.name = device_get_devnode(dev, NULL, NULL, NULL, &tmp);
+	if (!req.name)
+		return -ENOMEM;
+
+	req.mode = 0;
+	req.dev = dev;
+
+	return devtmpfs_submit_req(&req, tmp);
+}
+
+static int dev_mkdir(const char *name, umode_t mode)
+{
+	struct dentry *dentry;
+	struct path path;
+	int err;
+
+	dentry = kern_path_create(AT_FDCWD, name, &path, LOOKUP_DIRECTORY);
+	if (IS_ERR(dentry))
+		return PTR_ERR(dentry);
+
+	err = vfs_mkdir(&nop_mnt_idmap, d_inode(path.dentry), dentry, mode);
+	if (!err)
+		/* mark as kernel-created inode */
+		d_inode(dentry)->i_private = &thread;
+	done_path_create(&path, dentry);
+	return err;
+}
+
+static int create_path(const char *nodepath)
+{
+	char *path;
+	char *s;
+	int err = 0;
+
+	/* parent directories do not exist, create them */
+	path = kstrdup(nodepath, GFP_KERNEL);
+	if (!path)
+		return -ENOMEM;
+
+	s = path;
+	for (;;) {
+		s = strchr(s, '/');
+		if (!s)
+			break;
+		s[0] = '\0';
+		err = dev_mkdir(path, 0755);
+		if (err && err != -EEXIST)
+			break;
+		s[0] = '/';
+		s++;
+	}
+	kfree(path);
+	return err;
+}
+
+static int handle_create(const char *nodename, umode_t mode, kuid_t uid,
+			 kgid_t gid, struct device *dev)
+{
+	struct dentry *dentry;
+	struct path path;
+	int err;
+
+	dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
+	if (dentry == ERR_PTR(-ENOENT)) {
+		create_path(nodename);
+		dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
+	}
+	if (IS_ERR(dentry))
+		return PTR_ERR(dentry);
+
+	err = vfs_mknod(&nop_mnt_idmap, d_inode(path.dentry), dentry, mode,
+			dev->devt);
+	if (!err) {
+		struct iattr newattrs;
+
+		newattrs.ia_mode = mode;
+		newattrs.ia_uid = uid;
+		newattrs.ia_gid = gid;
+		newattrs.ia_valid = ATTR_MODE|ATTR_UID|ATTR_GID;
+		inode_lock(d_inode(dentry));
+		notify_change(&nop_mnt_idmap, dentry, &newattrs, NULL);
+		inode_unlock(d_inode(dentry));
+
+		/* mark as kernel-created inode */
+		d_inode(dentry)->i_private = &thread;
+	}
+	done_path_create(&path, dentry);
+	return err;
+}
+
+static int dev_rmdir(const char *name)
+{
+	struct path parent;
+	struct dentry *dentry;
+	int err;
+
+	dentry = kern_path_locked(name, &parent);
+	if (IS_ERR(dentry))
+		return PTR_ERR(dentry);
+	if (d_really_is_positive(dentry)) {
+		if (d_inode(dentry)->i_private == &thread)
+			err = vfs_rmdir(&nop_mnt_idmap, d_inode(parent.dentry),
+					dentry);
+		else
+			err = -EPERM;
+	} else {
+		err = -ENOENT;
+	}
+	dput(dentry);
+	inode_unlock(d_inode(parent.dentry));
+	path_put(&parent);
+	return err;
+}
+
+static int delete_path(const char *nodepath)
+{
+	char *path;
+	int err = 0;
+
+	path = kstrdup(nodepath, GFP_KERNEL);
+	if (!path)
+		return -ENOMEM;
+
+	for (;;) {
+		char *base;
+
+		base = strrchr(path, '/');
+		if (!base)
+			break;
+		base[0] = '\0';
+		err = dev_rmdir(path);
+		if (err)
+			break;
+	}
+
+	kfree(path);
+	return err;
+}
+
+static int dev_mynode(struct device *dev, struct inode *inode, struct kstat *stat)
+{
+	/* did we create it */
+	if (inode->i_private != &thread)
+		return 0;
+
+	/* does the dev_t match */
+	if (is_blockdev(dev)) {
+		if (!S_ISBLK(stat->mode))
+			return 0;
+	} else {
+		if (!S_ISCHR(stat->mode))
+			return 0;
+	}
+	if (stat->rdev != dev->devt)
+		return 0;
+
+	/* ours */
+	return 1;
+}
+
+static int handle_remove(const char *nodename, struct device *dev)
+{
+	struct path parent;
+	struct dentry *dentry;
+	int deleted = 0;
+	int err;
+
+	dentry = kern_path_locked(nodename, &parent);
+	if (IS_ERR(dentry))
+		return PTR_ERR(dentry);
+
+	if (d_really_is_positive(dentry)) {
+		struct kstat stat;
+		struct path p = {.mnt = parent.mnt, .dentry = dentry};
+		err = vfs_getattr(&p, &stat, STATX_TYPE | STATX_MODE,
+				  AT_STATX_SYNC_AS_STAT);
+		if (!err && dev_mynode(dev, d_inode(dentry), &stat)) {
+			struct iattr newattrs;
+			/*
+			 * before unlinking this node, reset permissions
+			 * of possible references like hardlinks
+			 */
+			newattrs.ia_uid = GLOBAL_ROOT_UID;
+			newattrs.ia_gid = GLOBAL_ROOT_GID;
+			newattrs.ia_mode = stat.mode & ~0777;
+			newattrs.ia_valid =
+				ATTR_UID|ATTR_GID|ATTR_MODE;
+			inode_lock(d_inode(dentry));
+			notify_change(&nop_mnt_idmap, dentry, &newattrs, NULL);
+			inode_unlock(d_inode(dentry));
+			err = vfs_unlink(&nop_mnt_idmap, d_inode(parent.dentry),
+					 dentry, NULL);
+			if (!err || err == -ENOENT)
+				deleted = 1;
+		}
+	} else {
+		err = -ENOENT;
+	}
+	dput(dentry);
+	inode_unlock(d_inode(parent.dentry));
+
+	path_put(&parent);
+	if (deleted && strchr(nodename, '/'))
+		delete_path(nodename);
+	return err;
+}
+
+/*
+ * If configured, or requested by the commandline, devtmpfs will be
+ * auto-mounted after the kernel mounted the root filesystem.
+ */
+int __init devtmpfs_mount(void)
+{
+	int err;
+
+	if (!mount_dev)
+		return 0;
+
+	if (!thread)
+		return 0;
+
+	err = init_mount("devtmpfs", "dev", "devtmpfs", DEVTMPFS_MFLAGS, NULL);
+	if (err)
+		pr_info("error mounting %d\n", err);
+	else
+		pr_info("mounted\n");
+	return err;
+}
+
+static __initdata DECLARE_COMPLETION(setup_done);
+
+static int handle(const char *name, umode_t mode, kuid_t uid, kgid_t gid,
+		  struct device *dev)
+{
+	if (mode)
+		return handle_create(name, mode, uid, gid, dev);
+	else
+		return handle_remove(name, dev);
+}
+
+static void __noreturn devtmpfs_work_loop(void)
+{
+	while (1) {
+		spin_lock(&req_lock);
+		while (requests) {
+			struct req *req = requests;
+			requests = NULL;
+			spin_unlock(&req_lock);
+			while (req) {
+				struct req *next = req->next;
+				req->err = handle(req->name, req->mode,
+						  req->uid, req->gid, req->dev);
+				complete(&req->done);
+				req = next;
+			}
+			spin_lock(&req_lock);
+		}
+		__set_current_state(TASK_INTERRUPTIBLE);
+		spin_unlock(&req_lock);
+		schedule();
+	}
+}
+
+static noinline int __init devtmpfs_setup(void *p)
+{
+	int err;
+
+	err = ksys_unshare(CLONE_NEWNS);
+	if (err)
+		goto out;
+	err = init_mount("devtmpfs", "/", "devtmpfs", DEVTMPFS_MFLAGS, NULL);
+	if (err)
+		goto out;
+	init_chdir("/.."); /* will traverse into overmounted root */
+	init_chroot(".");
+out:
+	*(int *)p = err;
+	return err;
+}
+
+/*
+ * The __ref is because devtmpfs_setup needs to be __init for the routines it
+ * calls.  That call is done while devtmpfs_init, which is marked __init,
+ * synchronously waits for it to complete.
+ */
+static int __ref devtmpfsd(void *p)
+{
+	int err = devtmpfs_setup(p);
+
+	complete(&setup_done);
+	if (err)
+		return err;
+	devtmpfs_work_loop();
+	return 0;
+}
+
+/*
+ * Create devtmpfs instance, driver-core devices will add their device
+ * nodes here.
+ */
+int __init devtmpfs_init(void)
+{
+	char opts[] = "mode=0755";
+	int err;
+
+	mnt = vfs_kern_mount(&internal_fs_type, 0, "devtmpfs", opts);
+	if (IS_ERR(mnt)) {
+		pr_err("unable to create devtmpfs %ld\n", PTR_ERR(mnt));
+		return PTR_ERR(mnt);
+	}
+	err = register_filesystem(&dev_fs_type);
+	if (err) {
+		pr_err("unable to register devtmpfs type %d\n", err);
+		return err;
+	}
+
+	thread = kthread_run(devtmpfsd, &err, "kdevtmpfs");
+	if (!IS_ERR(thread)) {
+		wait_for_completion(&setup_done);
+	} else {
+		err = PTR_ERR(thread);
+		thread = NULL;
+	}
+
+	if (err) {
+		pr_err("unable to create devtmpfs %d\n", err);
+		unregister_filesystem(&dev_fs_type);
+		thread = NULL;
+		return err;
+	}
+
+	pr_info("initialized\n");
+	return 0;
+}