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author | root <root@artemis.panaceas.org> | 2015-12-25 04:40:36 +0000 |
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committer | root <root@artemis.panaceas.org> | 2015-12-25 04:40:36 +0000 |
commit | 849369d6c66d3054688672f97d31fceb8e8230fb (patch) | |
tree | 6135abc790ca67dedbe07c39806591e70eda81ce /drivers/base/devtmpfs.c | |
download | linux-3.0.35-kobo-849369d6c66d3054688672f97d31fceb8e8230fb.tar.gz linux-3.0.35-kobo-849369d6c66d3054688672f97d31fceb8e8230fb.tar.bz2 linux-3.0.35-kobo-849369d6c66d3054688672f97d31fceb8e8230fb.zip |
initial_commit
Diffstat (limited to 'drivers/base/devtmpfs.c')
-rw-r--r-- | drivers/base/devtmpfs.c | 396 |
1 files changed, 396 insertions, 0 deletions
diff --git a/drivers/base/devtmpfs.c b/drivers/base/devtmpfs.c new file mode 100644 index 00000000..82bbb596 --- /dev/null +++ b/drivers/base/devtmpfs.c @@ -0,0 +1,396 @@ +/* + * 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; +} |