fs/proc/root.c

   1 /*
   2  *  linux/fs/proc/root.c
   3  *
   4  *  Copyright (C) 1991, 1992 Linus Torvalds
   5  *
   6  *  proc root directory handling functions
   7  */
   8
   9 #include <linux/uaccess.h>
  10
  11 #include <linux/errno.h>
  12 #include <linux/time.h>
  13 #include <linux/proc_fs.h>
  14 #include <linux/stat.h>
  15 #include <linux/init.h>
  16 #include <linux/sched.h>
  17 #include <linux/sched/stat.h>
  18 #include <linux/module.h>
  19 #include <linux/bitops.h>
  20 #include <linux/user_namespace.h>
  21 #include <linux/mount.h>
  22 #include <linux/pid_namespace.h>
  23 #include <linux/parser.h>
  24 #include <linux/cred.h>
  25
  26 #include "internal.h"
  27
  28 enum {
  29         Opt_gid, Opt_hidepid, Opt_err,
  30 };
  31
  32 static const match_table_t tokens = {
  33         {Opt_hidepid, "hidepid=%u"},
  34         {Opt_gid, "gid=%u"},
  35         {Opt_err, NULL},
  36 };
  37
  38 int proc_parse_options(char *options, struct pid_namespace *pid)
  39 {
  40         char *p;
  41         substring_t args[MAX_OPT_ARGS];
  42         int option;
  43
  44         if (!options)
  45                 return 1;
  46
  47         while ((p = strsep(&options, ",")) != NULL) {
  48                 int token;
  49                 if (!*p)
  50                         continue;
  51
  52                 args[0].to = args[0].from = NULL;
  53                 token = match_token(p, tokens, args);
  54                 switch (token) {
  55                 case Opt_gid:
  56                         if (match_int(&args[0], &option))
  57                                 return 0;
  58                         pid->pid_gid = make_kgid(current_user_ns(), option);
  59                         break;
  60                 case Opt_hidepid:
  61                         if (match_int(&args[0], &option))
  62                                 return 0;
  63                         if (option < HIDEPID_OFF ||
  64                             option > HIDEPID_INVISIBLE) {
  65                                 pr_err("proc: hidepid value must be between 0 and 2.\n");
  66                                 return 0;
  67                         }
  68                         pid->hide_pid = option;
  69                         break;
  70                 default:
  71                         pr_err("proc: unrecognized mount option \"%s\" "
  72                                "or missing value\n", p);
  73                         return 0;
  74                 }
  75         }
  76
  77         return 1;
  78 }
  79
  80 int proc_remount(struct super_block *sb, int *flags, char *data)
  81 {
  82         struct pid_namespace *pid = sb->s_fs_info;
  83
  84         sync_filesystem(sb);
  85         return !proc_parse_options(data, pid);
  86 }
  87
  88 static struct dentry *proc_mount(struct file_system_type *fs_type,
  89         int flags, const char *dev_name, void *data)
  90 {
  91         struct pid_namespace *ns;
  92
  93         if (flags & MS_KERNMOUNT) {
  94                 ns = data;
  95                 data = NULL;
  96         } else {
  97                 ns = task_active_pid_ns(current);
  98         }
  99
 100         return mount_ns(fs_type, flags, data, ns, ns->user_ns, proc_fill_super);
 101 }
 102
 103 static void proc_kill_sb(struct super_block *sb)
 104 {
 105         struct pid_namespace *ns;
 106
 107         ns = (struct pid_namespace *)sb->s_fs_info;
 108         if (ns->proc_self)
 109                 dput(ns->proc_self);
 110         if (ns->proc_thread_self)
 111                 dput(ns->proc_thread_self);
 112         kill_anon_super(sb);
 113         put_pid_ns(ns);
 114 }
 115
 116 static struct file_system_type proc_fs_type = {
 117         .name           = "proc",
 118         .mount          = proc_mount,
 119         .kill_sb        = proc_kill_sb,
 120         .fs_flags       = FS_USERNS_MOUNT,
 121 };
 122
 123 void __init proc_root_init(void)
 124 {
 125         int err;
 126
 127         proc_init_inodecache();
 128         set_proc_pid_nlink();
 129         err = register_filesystem(&proc_fs_type);
 130         if (err)
 131                 return;
 132
 133         proc_self_init();
 134         proc_thread_self_init();
 135         proc_symlink("mounts", NULL, "self/mounts");
 136
 137         proc_net_init();
 138
 139 #ifdef CONFIG_SYSVIPC
 140         proc_mkdir("sysvipc", NULL);
 141 #endif
 142         proc_mkdir("fs", NULL);
 143         proc_mkdir("driver", NULL);
 144         proc_create_mount_point("fs/nfsd"); /* somewhere for the nfsd filesystem to be mounted */
 145 #if defined(CONFIG_SUN_OPENPROMFS) || defined(CONFIG_SUN_OPENPROMFS_MODULE)
 146         /* just give it a mountpoint */
 147         proc_create_mount_point("openprom");
 148 #endif
 149         proc_tty_init();
 150         proc_mkdir("bus", NULL);
 151         proc_sys_init();
 152 }
 153
 154 static int proc_root_getattr(const struct path *path, struct kstat *stat,
 155                              u32 request_mask, unsigned int query_flags)
 156 {
 157         generic_fillattr(d_inode(path->dentry), stat);
 158         stat->nlink = proc_root.nlink + nr_processes();
 159         return 0;
 160 }
 161
 162 static struct dentry *proc_root_lookup(struct inode * dir, struct dentry * dentry, unsigned int flags)
 163 {
 164         if (!proc_pid_lookup(dir, dentry, flags))
 165                 return NULL;
 166
 167         return proc_lookup(dir, dentry, flags);
 168 }
 169
 170 static int proc_root_readdir(struct file *file, struct dir_context *ctx)
 171 {
 172         if (ctx->pos < FIRST_PROCESS_ENTRY) {
 173                 int error = proc_readdir(file, ctx);
 174                 if (unlikely(error <= 0))
 175                         return error;
 176                 ctx->pos = FIRST_PROCESS_ENTRY;
 177         }
 178
 179         return proc_pid_readdir(file, ctx);
 180 }
 181
 182 /*
 183  * The root /proc directory is special, as it has the
 184  * <pid> directories. Thus we don't use the generic
 185  * directory handling functions for that..
 186  */
 187 static const struct file_operations proc_root_operations = {
 188         .read            = generic_read_dir,
 189         .iterate_shared  = proc_root_readdir,
 190         .llseek         = generic_file_llseek,
 191 };
 192
 193 /*
 194  * proc root can do almost nothing..
 195  */
 196 static const struct inode_operations proc_root_inode_operations = {
 197         .lookup         = proc_root_lookup,
 198         .getattr        = proc_root_getattr,
 199 };
 200
 201 /*
 202  * This is the root "inode" in the /proc tree..
 203  */
 204 struct proc_dir_entry proc_root = {
 205         .low_ino        = PROC_ROOT_INO,
 206         .namelen        = 5,
 207         .mode           = S_IFDIR | S_IRUGO | S_IXUGO,
 208         .nlink          = 2,
 209         .count          = ATOMIC_INIT(1),
 210         .proc_iops      = &proc_root_inode_operations,
 211         .proc_fops      = &proc_root_operations,
 212         .parent         = &proc_root,
 213         .subdir         = RB_ROOT,
 214         .name           = "/proc",
 215 };
 216
 217 int pid_ns_prepare_proc(struct pid_namespace *ns)
 218 {
 219         struct vfsmount *mnt;
 220
 221         mnt = kern_mount_data(&proc_fs_type, ns);
 222         if (IS_ERR(mnt))
 223                 return PTR_ERR(mnt);
 224
 225         ns->proc_mnt = mnt;
 226         return 0;
 227 }
 228
 229 void pid_ns_release_proc(struct pid_namespace *ns)
 230 {
 231         kern_unmount(ns->proc_mnt);
 232 }