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 } 233