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 /* Does the mounter have privilege over the pid namespace? */ 116 if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN)) 117 return ERR_PTR(-EPERM); 118 } 119 120 sb = sget(fs_type, proc_test_super, proc_set_super, flags, ns); 121 if (IS_ERR(sb)) 122 return ERR_CAST(sb); 123 124 if (!proc_parse_options(options, ns)) { 125 deactivate_locked_super(sb); 126 return ERR_PTR(-EINVAL); 127 } 128 129 if (!sb->s_root) { 130 err = proc_fill_super(sb); 131 if (err) { 132 deactivate_locked_super(sb); 133 return ERR_PTR(err); 134 } 135 136 sb->s_flags |= MS_ACTIVE; 137 /* User space would break if executables appear on proc */ 138 sb->s_iflags |= SB_I_NOEXEC; 139 } 140 141 return dget(sb->s_root); 142 } 143 144 static void proc_kill_sb(struct super_block *sb) 145 { 146 struct pid_namespace *ns; 147 148 ns = (struct pid_namespace *)sb->s_fs_info; 149 if (ns->proc_self) 150 dput(ns->proc_self); 151 if (ns->proc_thread_self) 152 dput(ns->proc_thread_self); 153 kill_anon_super(sb); 154 put_pid_ns(ns); 155 } 156 157 static struct file_system_type proc_fs_type = { 158 .name = "proc", 159 .mount = proc_mount, 160 .kill_sb = proc_kill_sb, 161 .fs_flags = FS_USERNS_VISIBLE | FS_USERNS_MOUNT, 162 }; 163 164 void __init proc_root_init(void) 165 { 166 int err; 167 168 proc_init_inodecache(); 169 err = register_filesystem(&proc_fs_type); 170 if (err) 171 return; 172 173 proc_self_init(); 174 proc_thread_self_init(); 175 proc_symlink("mounts", NULL, "self/mounts"); 176 177 proc_net_init(); 178 179 #ifdef CONFIG_SYSVIPC 180 proc_mkdir("sysvipc", NULL); 181 #endif 182 proc_mkdir("fs", NULL); 183 proc_mkdir("driver", NULL); 184 proc_create_mount_point("fs/nfsd"); /* somewhere for the nfsd filesystem to be mounted */ 185 #if defined(CONFIG_SUN_OPENPROMFS) || defined(CONFIG_SUN_OPENPROMFS_MODULE) 186 /* just give it a mountpoint */ 187 proc_create_mount_point("openprom"); 188 #endif 189 proc_tty_init(); 190 proc_mkdir("bus", NULL); 191 proc_sys_init(); 192 } 193 194 static int proc_root_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat 195 ) 196 { 197 generic_fillattr(d_inode(dentry), stat); 198 stat->nlink = proc_root.nlink + nr_processes(); 199 return 0; 200 } 201 202 static struct dentry *proc_root_lookup(struct inode * dir, struct dentry * dentry, unsigned int flags) 203 { 204 if (!proc_pid_lookup(dir, dentry, flags)) 205 return NULL; 206 207 return proc_lookup(dir, dentry, flags); 208 } 209 210 static int proc_root_readdir(struct file *file, struct dir_context *ctx) 211 { 212 if (ctx->pos < FIRST_PROCESS_ENTRY) { 213 int error = proc_readdir(file, ctx); 214 if (unlikely(error <= 0)) 215 return error; 216 ctx->pos = FIRST_PROCESS_ENTRY; 217 } 218 219 return proc_pid_readdir(file, ctx); 220 } 221 222 /* 223 * The root /proc directory is special, as it has the 224 * <pid> directories. Thus we don't use the generic 225 * directory handling functions for that.. 226 */ 227 static const struct file_operations proc_root_operations = { 228 .read = generic_read_dir, 229 .iterate_shared = proc_root_readdir, 230 .llseek = generic_file_llseek, 231 }; 232 233 /* 234 * proc root can do almost nothing.. 235 */ 236 static const struct inode_operations proc_root_inode_operations = { 237 .lookup = proc_root_lookup, 238 .getattr = proc_root_getattr, 239 }; 240 241 /* 242 * This is the root "inode" in the /proc tree.. 243 */ 244 struct proc_dir_entry proc_root = { 245 .low_ino = PROC_ROOT_INO, 246 .namelen = 5, 247 .mode = S_IFDIR | S_IRUGO | S_IXUGO, 248 .nlink = 2, 249 .count = ATOMIC_INIT(1), 250 .proc_iops = &proc_root_inode_operations, 251 .proc_fops = &proc_root_operations, 252 .parent = &proc_root, 253 .subdir = RB_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 } 273