// SPDX-License-Identifier: GPL-2.0 /* * 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 & SB_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) { proc_init_kmemcache(); set_proc_pid_nlink(); proc_self_init(); proc_thread_self_init(); proc_symlink("mounts", NULL, "self/mounts"); proc_net_init(); 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(); register_filesystem(&proc_fs_type); } 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, .refcnt = REFCOUNT_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); }