| /* |
| * 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 the name of the |
| * device, owned by root and have a default mode of 0600. Subsystems |
| * can overwrite the default setting if needed. |
| */ |
| |
| #include <linux/kernel.h> |
| #include <linux/syscalls.h> |
| #include <linux/mount.h> |
| #include <linux/device.h> |
| #include <linux/genhd.h> |
| #include <linux/namei.h> |
| #include <linux/fs.h> |
| #include <linux/shmem_fs.h> |
| #include <linux/ramfs.h> |
| #include <linux/cred.h> |
| #include <linux/sched.h> |
| #include <linux/init_task.h> |
| #include <linux/slab.h> |
| |
| static struct vfsmount *dev_mnt; |
| |
| #if defined CONFIG_DEVTMPFS_MOUNT |
| static int mount_dev = 1; |
| #else |
| static int mount_dev; |
| #endif |
| |
| static DEFINE_MUTEX(dirlock); |
| |
| static int __init mount_param(char *str) |
| { |
| mount_dev = simple_strtoul(str, NULL, 0); |
| return 1; |
| } |
| __setup("devtmpfs.mount=", mount_param); |
| |
| static struct dentry *dev_mount(struct file_system_type *fs_type, int flags, |
| const char *dev_name, void *data) |
| { |
| #ifdef CONFIG_TMPFS |
| return mount_single(fs_type, flags, data, shmem_fill_super); |
| #else |
| return mount_single(fs_type, flags, data, ramfs_fill_super); |
| #endif |
| } |
| |
| static struct file_system_type dev_fs_type = { |
| .name = "devtmpfs", |
| .mount = dev_mount, |
| .kill_sb = kill_litter_super, |
| }; |
| |
| #ifdef CONFIG_BLOCK |
| static inline int is_blockdev(struct device *dev) |
| { |
| return dev->class == &block_class; |
| } |
| #else |
| static inline int is_blockdev(struct device *dev) { return 0; } |
| #endif |
| |
| static int dev_mkdir(const char *name, mode_t mode) |
| { |
| struct nameidata nd; |
| struct dentry *dentry; |
| int err; |
| |
| err = vfs_path_lookup(dev_mnt->mnt_root, dev_mnt, |
| name, LOOKUP_PARENT, &nd); |
| if (err) |
| return err; |
| |
| dentry = lookup_create(&nd, 1); |
| if (!IS_ERR(dentry)) { |
| err = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode); |
| if (!err) |
| /* mark as kernel-created inode */ |
| dentry->d_inode->i_private = &dev_mnt; |
| dput(dentry); |
| } else { |
| err = PTR_ERR(dentry); |
| } |
| |
| mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
| path_put(&nd.path); |
| return err; |
| } |
| |
| static int create_path(const char *nodepath) |
| { |
| int err; |
| |
| mutex_lock(&dirlock); |
| err = dev_mkdir(nodepath, 0755); |
| if (err == -ENOENT) { |
| char *path; |
| char *s; |
| |
| /* parent directories do not exist, create them */ |
| path = kstrdup(nodepath, GFP_KERNEL); |
| if (!path) { |
| err = -ENOMEM; |
| goto out; |
| } |
| 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); |
| } |
| out: |
| mutex_unlock(&dirlock); |
| return err; |
| } |
| |
| int devtmpfs_create_node(struct device *dev) |
| { |
| const char *tmp = NULL; |
| const char *nodename; |
| const struct cred *curr_cred; |
| mode_t mode = 0; |
| struct nameidata nd; |
| struct dentry *dentry; |
| int err; |
| |
| if (!dev_mnt) |
| return 0; |
| |
| nodename = device_get_devnode(dev, &mode, &tmp); |
| if (!nodename) |
| return -ENOMEM; |
| |
| if (mode == 0) |
| mode = 0600; |
| if (is_blockdev(dev)) |
| mode |= S_IFBLK; |
| else |
| mode |= S_IFCHR; |
| |
| curr_cred = override_creds(&init_cred); |
| |
| err = vfs_path_lookup(dev_mnt->mnt_root, dev_mnt, |
| nodename, LOOKUP_PARENT, &nd); |
| if (err == -ENOENT) { |
| create_path(nodename); |
| err = vfs_path_lookup(dev_mnt->mnt_root, dev_mnt, |
| nodename, LOOKUP_PARENT, &nd); |
| } |
| if (err) |
| goto out; |
| |
| dentry = lookup_create(&nd, 0); |
| if (!IS_ERR(dentry)) { |
| err = vfs_mknod(nd.path.dentry->d_inode, |
| dentry, mode, dev->devt); |
| if (!err) { |
| struct iattr newattrs; |
| |
| /* fixup possibly umasked mode */ |
| newattrs.ia_mode = mode; |
| newattrs.ia_valid = ATTR_MODE; |
| mutex_lock(&dentry->d_inode->i_mutex); |
| notify_change(dentry, &newattrs); |
| mutex_unlock(&dentry->d_inode->i_mutex); |
| |
| /* mark as kernel-created inode */ |
| dentry->d_inode->i_private = &dev_mnt; |
| } |
| dput(dentry); |
| } else { |
| err = PTR_ERR(dentry); |
| } |
| |
| mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
| path_put(&nd.path); |
| out: |
| kfree(tmp); |
| revert_creds(curr_cred); |
| return err; |
| } |
| |
| static int dev_rmdir(const char *name) |
| { |
| struct nameidata nd; |
| struct dentry *dentry; |
| int err; |
| |
| err = vfs_path_lookup(dev_mnt->mnt_root, dev_mnt, |
| name, LOOKUP_PARENT, &nd); |
| if (err) |
| return err; |
| |
| mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
| dentry = lookup_one_len(nd.last.name, nd.path.dentry, nd.last.len); |
| if (!IS_ERR(dentry)) { |
| if (dentry->d_inode) { |
| if (dentry->d_inode->i_private == &dev_mnt) |
| err = vfs_rmdir(nd.path.dentry->d_inode, |
| dentry); |
| else |
| err = -EPERM; |
| } else { |
| err = -ENOENT; |
| } |
| dput(dentry); |
| } else { |
| err = PTR_ERR(dentry); |
| } |
| |
| mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
| path_put(&nd.path); |
| return err; |
| } |
| |
| static int delete_path(const char *nodepath) |
| { |
| const char *path; |
| int err = 0; |
| |
| path = kstrdup(nodepath, GFP_KERNEL); |
| if (!path) |
| return -ENOMEM; |
| |
| mutex_lock(&dirlock); |
| for (;;) { |
| char *base; |
| |
| base = strrchr(path, '/'); |
| if (!base) |
| break; |
| base[0] = '\0'; |
| err = dev_rmdir(path); |
| if (err) |
| break; |
| } |
| mutex_unlock(&dirlock); |
| |
| 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 != &dev_mnt) |
| 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; |
| } |
| |
| int devtmpfs_delete_node(struct device *dev) |
| { |
| const char *tmp = NULL; |
| const char *nodename; |
| const struct cred *curr_cred; |
| struct nameidata nd; |
| struct dentry *dentry; |
| struct kstat stat; |
| int deleted = 1; |
| int err; |
| |
| if (!dev_mnt) |
| return 0; |
| |
| nodename = device_get_devnode(dev, NULL, &tmp); |
| if (!nodename) |
| return -ENOMEM; |
| |
| curr_cred = override_creds(&init_cred); |
| err = vfs_path_lookup(dev_mnt->mnt_root, dev_mnt, |
| nodename, LOOKUP_PARENT, &nd); |
| if (err) |
| goto out; |
| |
| mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
| dentry = lookup_one_len(nd.last.name, nd.path.dentry, nd.last.len); |
| if (!IS_ERR(dentry)) { |
| if (dentry->d_inode) { |
| err = vfs_getattr(nd.path.mnt, dentry, &stat); |
| if (!err && dev_mynode(dev, dentry->d_inode, &stat)) { |
| struct iattr newattrs; |
| /* |
| * before unlinking this node, reset permissions |
| * of possible references like hardlinks |
| */ |
| newattrs.ia_uid = 0; |
| newattrs.ia_gid = 0; |
| newattrs.ia_mode = stat.mode & ~0777; |
| newattrs.ia_valid = |
| ATTR_UID|ATTR_GID|ATTR_MODE; |
| mutex_lock(&dentry->d_inode->i_mutex); |
| notify_change(dentry, &newattrs); |
| mutex_unlock(&dentry->d_inode->i_mutex); |
| err = vfs_unlink(nd.path.dentry->d_inode, |
| dentry); |
| if (!err || err == -ENOENT) |
| deleted = 1; |
| } |
| } else { |
| err = -ENOENT; |
| } |
| dput(dentry); |
| } else { |
| err = PTR_ERR(dentry); |
| } |
| mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
| |
| path_put(&nd.path); |
| if (deleted && strchr(nodename, '/')) |
| delete_path(nodename); |
| out: |
| kfree(tmp); |
| revert_creds(curr_cred); |
| return err; |
| } |
| |
| /* |
| * 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 err; |
| |
| if (!mount_dev) |
| return 0; |
| |
| if (!dev_mnt) |
| return 0; |
| |
| err = sys_mount("devtmpfs", (char *)mntdir, "devtmpfs", MS_SILENT, NULL); |
| if (err) |
| printk(KERN_INFO "devtmpfs: error mounting %i\n", err); |
| else |
| printk(KERN_INFO "devtmpfs: mounted\n"); |
| return err; |
| } |
| |
| /* |
| * Create devtmpfs instance, driver-core devices will add their device |
| * nodes here. |
| */ |
| int __init devtmpfs_init(void) |
| { |
| int err; |
| struct vfsmount *mnt; |
| char options[] = "mode=0755"; |
| |
| err = register_filesystem(&dev_fs_type); |
| if (err) { |
| printk(KERN_ERR "devtmpfs: unable to register devtmpfs " |
| "type %i\n", err); |
| return err; |
| } |
| |
| mnt = kern_mount_data(&dev_fs_type, options); |
| if (IS_ERR(mnt)) { |
| err = PTR_ERR(mnt); |
| printk(KERN_ERR "devtmpfs: unable to create devtmpfs %i\n", err); |
| unregister_filesystem(&dev_fs_type); |
| return err; |
| } |
| dev_mnt = mnt; |
| |
| printk(KERN_INFO "devtmpfs: initialized\n"); |
| return 0; |
| } |