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