/* *  linux/fs/proc/root.c * *  Copyright (C) 1991, 1992 Linus Torvalds * *  proc root directory handling functions */ #include <linux/uaccess.h> #include <linux/errno.h>#include <linux/time.h>#include <linux/proc_fs.h>#include <linux/stat.h>#include <linux/init.h>#include <linux/sched.h>#include <linux/sched/stat.h>#include <linux/module.h>#include <linux/bitops.h>#include <linux/user_namespace.h>#include <linux/mount.h>#include <linux/pid_namespace.h>#include <linux/parser.h>#include <linux/cred.h> #include "internal.h" enum {	Opt_gid, Opt_hidepid, Opt_err,}; static const match_table_t tokens = {	{Opt_hidepid, "hidepid=%u"},	{Opt_gid, "gid=%u"},	{Opt_err, NULL},}; int proc_parse_options(char *options, struct pid_namespace *pid){	char *p;	substring_t args[MAX_OPT_ARGS];	int option; 	if (!options)		return 1; 	while ((p = strsep(&options, ",")) != NULL) {		int token;		if (!*p)			continue; 		args[0].to = args[0].from = NULL;		token = match_token(p, tokens, args);		switch (token) {		case Opt_gid:			if (match_int(&args[0], &option))				return 0;			pid->pid_gid = make_kgid(current_user_ns(), option);			break;		case Opt_hidepid:			if (match_int(&args[0], &option))				return 0;			if (option < HIDEPID_OFF ||			    option > HIDEPID_INVISIBLE) {				pr_err("proc: hidepid value must be between 0 and 2.\n");				return 0;			}			pid->hide_pid = option;			break;		default:			pr_err("proc: unrecognized mount option \"%s\" "			       "or missing value\n", p);			return 0;		}	} 	return 1;} int proc_remount(struct super_block *sb, int *flags, char *data){	struct pid_namespace *pid = sb->s_fs_info; 	sync_filesystem(sb);	return !proc_parse_options(data, pid);} static struct dentry *proc_mount(struct file_system_type *fs_type,	int flags, const char *dev_name, void *data){	struct pid_namespace *ns; 	if (flags & MS_KERNMOUNT) {		ns = data;		data = NULL;	} else {		ns = task_active_pid_ns(current);	} 	return mount_ns(fs_type, flags, data, ns, ns->user_ns, proc_fill_super);} static void proc_kill_sb(struct super_block *sb){	struct pid_namespace *ns; 	ns = (struct pid_namespace *)sb->s_fs_info;	if (ns->proc_self)		dput(ns->proc_self);	if (ns->proc_thread_self)		dput(ns->proc_thread_self);	kill_anon_super(sb);	put_pid_ns(ns);} static struct file_system_type proc_fs_type = {	.name		= "proc",	.mount		= proc_mount,	.kill_sb	= proc_kill_sb,	.fs_flags	= FS_USERNS_MOUNT,}; void __init proc_root_init(void){	int err; 	proc_init_inodecache();	set_proc_pid_nlink();	err = register_filesystem(&proc_fs_type);	if (err)		return; 	proc_self_init();	proc_thread_self_init();	proc_symlink("mounts", NULL, "self/mounts"); 	proc_net_init(); #ifdef CONFIG_SYSVIPC	proc_mkdir("sysvipc", NULL);#endif	proc_mkdir("fs", NULL);	proc_mkdir("driver", NULL);	proc_create_mount_point("fs/nfsd"); /* somewhere for the nfsd filesystem to be mounted */#if defined(CONFIG_SUN_OPENPROMFS) || defined(CONFIG_SUN_OPENPROMFS_MODULE)	/* just give it a mountpoint */	proc_create_mount_point("openprom");#endif	proc_tty_init();	proc_mkdir("bus", NULL);	proc_sys_init();} static int proc_root_getattr(const struct path *path, struct kstat *stat,			     u32 request_mask, unsigned int query_flags){	generic_fillattr(d_inode(path->dentry), stat);	stat->nlink = proc_root.nlink + nr_processes();	return 0;} static struct dentry *proc_root_lookup(struct inode * dir, struct dentry * dentry, unsigned int flags){	if (!proc_pid_lookup(dir, dentry, flags))		return NULL;		return proc_lookup(dir, dentry, flags);} static int proc_root_readdir(struct file *file, struct dir_context *ctx){	if (ctx->pos < FIRST_PROCESS_ENTRY) {		int error = proc_readdir(file, ctx);		if (unlikely(error <= 0))			return error;		ctx->pos = FIRST_PROCESS_ENTRY;	} 	return proc_pid_readdir(file, ctx);} /* * The root /proc directory is special, as it has the * <pid> directories. Thus we don't use the generic * directory handling functions for that.. */static const struct file_operations proc_root_operations = {	.read		 = generic_read_dir,	.iterate_shared	 = proc_root_readdir,	.llseek		= generic_file_llseek,}; /* * proc root can do almost nothing.. */static const struct inode_operations proc_root_inode_operations = {	.lookup		= proc_root_lookup,	.getattr	= proc_root_getattr,}; /* * This is the root "inode" in the /proc tree.. */struct proc_dir_entry proc_root = {	.low_ino	= PROC_ROOT_INO, 	.namelen	= 5, 	.mode		= S_IFDIR | S_IRUGO | S_IXUGO, 	.nlink		= 2, 	.count		= ATOMIC_INIT(1),	.proc_iops	= &proc_root_inode_operations, 	.proc_fops	= &proc_root_operations,	.parent		= &proc_root,	.subdir		= RB_ROOT,	.name		= "/proc",}; int pid_ns_prepare_proc(struct pid_namespace *ns){	struct vfsmount *mnt; 	mnt = kern_mount_data(&proc_fs_type, ns);	if (IS_ERR(mnt))		return PTR_ERR(mnt); 	ns->proc_mnt = mnt;	return 0;} void pid_ns_release_proc(struct pid_namespace *ns){	kern_unmount(ns->proc_mnt);}