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 <asm/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/module.h>
  18 #include <linux/bitops.h>
  19 #include <linux/user_namespace.h>
  20 #include <linux/mount.h>
  21 #include <linux/pid_namespace.h>
  22 #include <linux/parser.h>
  23
  24 #include "internal.h"
  25
  26 static int proc_test_super(struct super_block *sb, void *data)
  27 {
  28         return sb->s_fs_info == data;
  29 }
  30
  31 static int proc_set_super(struct super_block *sb, void *data)
  32 {
  33         int err = set_anon_super(sb, NULL);
  34         if (!err) {
  35                 struct pid_namespace *ns = (struct pid_namespace *)data;
  36                 sb->s_fs_info = get_pid_ns(ns);
  37         }
  38         return err;
  39 }
  40
  41 enum {
  42         Opt_gid, Opt_hidepid, Opt_err,
  43 };
  44
  45 static const match_table_t tokens = {
  46         {Opt_hidepid, "hidepid=%u"},
  47         {Opt_gid, "gid=%u"},
  48         {Opt_err, NULL},
  49 };
  50
  51 static int proc_parse_options(char *options, struct pid_namespace *pid)
  52 {
  53         char *p;
  54         substring_t args[MAX_OPT_ARGS];
  55         int option;
  56
  57         if (!options)
  58                 return 1;
  59
  60         while ((p = strsep(&options, ",")) != NULL) {
  61                 int token;
  62                 if (!*p)
  63                         continue;
  64
  65                 args[0].to = args[0].from = NULL;
  66                 token = match_token(p, tokens, args);
  67                 switch (token) {
  68                 case Opt_gid:
  69                         if (match_int(&args[0], &option))
  70                                 return 0;
  71                         pid->pid_gid = make_kgid(current_user_ns(), option);
  72                         break;
  73                 case Opt_hidepid:
  74                         if (match_int(&args[0], &option))
  75                                 return 0;
  76                         if (option < 0 || option > 2) {
  77                                 pr_err("proc: hidepid value must be between 0 and 2.\n");
  78                                 return 0;
  79                         }
  80                         pid->hide_pid = option;
  81                         break;
  82                 default:
  83                         pr_err("proc: unrecognized mount option \"%s\" "
  84                                "or missing value\n", p);
  85                         return 0;
  86                 }
  87         }
  88
  89         return 1;
  90 }
  91
  92 int proc_remount(struct super_block *sb, int *flags, char *data)
  93 {
  94         struct pid_namespace *pid = sb->s_fs_info;
  95
  96         sync_filesystem(sb);
  97         return !proc_parse_options(data, pid);
  98 }
  99
 100 static struct dentry *proc_mount(struct file_system_type *fs_type,
 101         int flags, const char *dev_name, void *data)
 102 {
 103         int err;
 104         struct super_block *sb;
 105         struct pid_namespace *ns;
 106         char *options;
 107
 108         if (flags & MS_KERNMOUNT) {
 109                 ns = (struct pid_namespace *)data;
 110                 options = NULL;
 111         } else {
 112                 ns = task_active_pid_ns(current);
 113                 options = data;
 114
 115                 if (!capable(CAP_SYS_ADMIN) && !fs_fully_visible(fs_type))
 116                         return ERR_PTR(-EPERM);
 117
 118                 /* Does the mounter have privilege over the pid namespace? */
 119                 if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN))
 120                         return ERR_PTR(-EPERM);
 121         }
 122
 123         sb = sget(fs_type, proc_test_super, proc_set_super, flags, ns);
 124         if (IS_ERR(sb))
 125                 return ERR_CAST(sb);
 126
 127         if (!proc_parse_options(options, ns)) {
 128                 deactivate_locked_super(sb);
 129                 return ERR_PTR(-EINVAL);
 130         }
 131
 132         if (!sb->s_root) {
 133                 err = proc_fill_super(sb);
 134                 if (err) {
 135                         deactivate_locked_super(sb);
 136                         return ERR_PTR(err);
 137                 }
 138
 139                 sb->s_flags |= MS_ACTIVE;
 140         }
 141
 142         return dget(sb->s_root);
 143 }
 144
 145 static void proc_kill_sb(struct super_block *sb)
 146 {
 147         struct pid_namespace *ns;
 148
 149         ns = (struct pid_namespace *)sb->s_fs_info;
 150         if (ns->proc_self)
 151                 dput(ns->proc_self);
 152         if (ns->proc_thread_self)
 153                 dput(ns->proc_thread_self);
 154         kill_anon_super(sb);
 155         put_pid_ns(ns);
 156 }
 157
 158 static struct file_system_type proc_fs_type = {
 159         .name           = "proc",
 160         .mount          = proc_mount,
 161         .kill_sb        = proc_kill_sb,
 162         .fs_flags       = FS_USERNS_MOUNT,
 163 };
 164
 165 void __init proc_root_init(void)
 166 {
 167         int err;
 168
 169         proc_init_inodecache();
 170         err = register_filesystem(&proc_fs_type);
 171         if (err)
 172                 return;
 173
 174         proc_self_init();
 175         proc_thread_self_init();
 176         proc_symlink("mounts", NULL, "thread-self/mounts");
 177
 178         proc_net_init();
 179
 180 #ifdef CONFIG_SYSVIPC
 181         proc_mkdir("sysvipc", NULL);
 182 #endif
 183         proc_mkdir("fs", NULL);
 184         proc_mkdir("driver", NULL);
 185         proc_mkdir("fs/nfsd", NULL); /* somewhere for the nfsd filesystem to be mounted */
 186 #if defined(CONFIG_SUN_OPENPROMFS) || defined(CONFIG_SUN_OPENPROMFS_MODULE)
 187         /* just give it a mountpoint */
 188         proc_mkdir("openprom", NULL);
 189 #endif
 190         proc_tty_init();
 191         proc_mkdir("bus", NULL);
 192         proc_sys_init();
 193 }
 194
 195 static int proc_root_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat
 196 )
 197 {
 198         generic_fillattr(dentry->d_inode, stat);
 199         stat->nlink = proc_root.nlink + nr_processes();
 200         return 0;
 201 }
 202
 203 static struct dentry *proc_root_lookup(struct inode * dir, struct dentry * dentry, unsigned int flags)
 204 {
 205         if (!proc_lookup(dir, dentry, flags))
 206                 return NULL;
 207
 208         return proc_pid_lookup(dir, dentry, flags);
 209 }
 210
 211 static int proc_root_readdir(struct file *file, struct dir_context *ctx)
 212 {
 213         if (ctx->pos < FIRST_PROCESS_ENTRY) {
 214                 int error = proc_readdir(file, ctx);
 215                 if (unlikely(error <= 0))
 216                         return error;
 217                 ctx->pos = FIRST_PROCESS_ENTRY;
 218         }
 219
 220         return proc_pid_readdir(file, ctx);
 221 }
 222
 223 /*
 224  * The root /proc directory is special, as it has the
 225  * <pid> directories. Thus we don't use the generic
 226  * directory handling functions for that..
 227  */
 228 static const struct file_operations proc_root_operations = {
 229         .read            = generic_read_dir,
 230         .iterate         = proc_root_readdir,
 231         .llseek         = default_llseek,
 232 };
 233
 234 /*
 235  * proc root can do almost nothing..
 236  */
 237 static const struct inode_operations proc_root_inode_operations = {
 238         .lookup         = proc_root_lookup,
 239         .getattr        = proc_root_getattr,
 240 };
 241
 242 /*
 243  * This is the root "inode" in the /proc tree..
 244  */
 245 struct proc_dir_entry proc_root = {
 246         .low_ino        = PROC_ROOT_INO,
 247         .namelen        = 5,
 248         .mode           = S_IFDIR | S_IRUGO | S_IXUGO,
 249         .nlink          = 2,
 250         .count          = ATOMIC_INIT(1),
 251         .proc_iops      = &proc_root_inode_operations,
 252         .proc_fops      = &proc_root_operations,
 253         .parent         = &proc_root,
 254         .name           = "/proc",
 255 };
 256
 257 int pid_ns_prepare_proc(struct pid_namespace *ns)
 258 {
 259         struct vfsmount *mnt;
 260
 261         mnt = kern_mount_data(&proc_fs_type, ns);
 262         if (IS_ERR(mnt))
 263                 return PTR_ERR(mnt);
 264
 265         ns->proc_mnt = mnt;
 266         return 0;
 267 }
 268
 269 void pid_ns_release_proc(struct pid_namespace *ns)
 270 {
 271         kern_unmount(ns->proc_mnt);
 272 }