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