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/mount.h> 20 #include <linux/pid_namespace.h> 21 22 #include "internal.h" 23 24 static int proc_test_super(struct super_block *sb, void *data) 25 { 26 return sb->s_fs_info == data; 27 } 28 29 static int proc_set_super(struct super_block *sb, void *data) 30 { 31 struct pid_namespace *ns; 32 33 ns = (struct pid_namespace *)data; 34 sb->s_fs_info = get_pid_ns(ns); 35 return set_anon_super(sb, NULL); 36 } 37 38 static struct dentry *proc_mount(struct file_system_type *fs_type, 39 int flags, const char *dev_name, void *data) 40 { 41 int err; 42 struct super_block *sb; 43 struct pid_namespace *ns; 44 struct proc_inode *ei; 45 46 if (proc_mnt) { 47 /* Seed the root directory with a pid so it doesn't need 48 * to be special in base.c. I would do this earlier but 49 * the only task alive when /proc is mounted the first time 50 * is the init_task and it doesn't have any pids. 51 */ 52 ei = PROC_I(proc_mnt->mnt_sb->s_root->d_inode); 53 if (!ei->pid) 54 ei->pid = find_get_pid(1); 55 } 56 57 if (flags & MS_KERNMOUNT) 58 ns = (struct pid_namespace *)data; 59 else 60 ns = current->nsproxy->pid_ns; 61 62 sb = sget(fs_type, proc_test_super, proc_set_super, ns); 63 if (IS_ERR(sb)) 64 return ERR_CAST(sb); 65 66 if (!sb->s_root) { 67 sb->s_flags = flags; 68 err = proc_fill_super(sb); 69 if (err) { 70 deactivate_locked_super(sb); 71 return ERR_PTR(err); 72 } 73 74 ei = PROC_I(sb->s_root->d_inode); 75 if (!ei->pid) { 76 rcu_read_lock(); 77 ei->pid = get_pid(find_pid_ns(1, ns)); 78 rcu_read_unlock(); 79 } 80 81 sb->s_flags |= MS_ACTIVE; 82 } 83 84 return dget(sb->s_root); 85 } 86 87 static void proc_kill_sb(struct super_block *sb) 88 { 89 struct pid_namespace *ns; 90 91 ns = (struct pid_namespace *)sb->s_fs_info; 92 kill_anon_super(sb); 93 put_pid_ns(ns); 94 } 95 96 static struct file_system_type proc_fs_type = { 97 .name = "proc", 98 .mount = proc_mount, 99 .kill_sb = proc_kill_sb, 100 }; 101 102 void __init proc_root_init(void) 103 { 104 int err; 105 106 proc_init_inodecache(); 107 err = register_filesystem(&proc_fs_type); 108 if (err) 109 return; 110 proc_mnt = kern_mount_data(&proc_fs_type, &init_pid_ns); 111 if (IS_ERR(proc_mnt)) { 112 unregister_filesystem(&proc_fs_type); 113 return; 114 } 115 116 init_pid_ns.proc_mnt = proc_mnt; 117 proc_symlink("mounts", NULL, "self/mounts"); 118 119 proc_net_init(); 120 121 #ifdef CONFIG_SYSVIPC 122 proc_mkdir("sysvipc", NULL); 123 #endif 124 proc_mkdir("fs", NULL); 125 proc_mkdir("driver", NULL); 126 proc_mkdir("fs/nfsd", NULL); /* somewhere for the nfsd filesystem to be mounted */ 127 #if defined(CONFIG_SUN_OPENPROMFS) || defined(CONFIG_SUN_OPENPROMFS_MODULE) 128 /* just give it a mountpoint */ 129 proc_mkdir("openprom", NULL); 130 #endif 131 proc_tty_init(); 132 #ifdef CONFIG_PROC_DEVICETREE 133 proc_device_tree_init(); 134 #endif 135 proc_mkdir("bus", NULL); 136 proc_sys_init(); 137 } 138 139 static int proc_root_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat 140 ) 141 { 142 generic_fillattr(dentry->d_inode, stat); 143 stat->nlink = proc_root.nlink + nr_processes(); 144 return 0; 145 } 146 147 static struct dentry *proc_root_lookup(struct inode * dir, struct dentry * dentry, struct nameidata *nd) 148 { 149 if (!proc_lookup(dir, dentry, nd)) { 150 return NULL; 151 } 152 153 return proc_pid_lookup(dir, dentry, nd); 154 } 155 156 static int proc_root_readdir(struct file * filp, 157 void * dirent, filldir_t filldir) 158 { 159 unsigned int nr = filp->f_pos; 160 int ret; 161 162 if (nr < FIRST_PROCESS_ENTRY) { 163 int error = proc_readdir(filp, dirent, filldir); 164 if (error <= 0) 165 return error; 166 filp->f_pos = FIRST_PROCESS_ENTRY; 167 } 168 169 ret = proc_pid_readdir(filp, dirent, filldir); 170 return ret; 171 } 172 173 /* 174 * The root /proc directory is special, as it has the 175 * <pid> directories. Thus we don't use the generic 176 * directory handling functions for that.. 177 */ 178 static const struct file_operations proc_root_operations = { 179 .read = generic_read_dir, 180 .readdir = proc_root_readdir, 181 .llseek = default_llseek, 182 }; 183 184 /* 185 * proc root can do almost nothing.. 186 */ 187 static const struct inode_operations proc_root_inode_operations = { 188 .lookup = proc_root_lookup, 189 .getattr = proc_root_getattr, 190 }; 191 192 /* 193 * This is the root "inode" in the /proc tree.. 194 */ 195 struct proc_dir_entry proc_root = { 196 .low_ino = PROC_ROOT_INO, 197 .namelen = 5, 198 .name = "/proc", 199 .mode = S_IFDIR | S_IRUGO | S_IXUGO, 200 .nlink = 2, 201 .count = ATOMIC_INIT(1), 202 .proc_iops = &proc_root_inode_operations, 203 .proc_fops = &proc_root_operations, 204 .parent = &proc_root, 205 }; 206 207 int pid_ns_prepare_proc(struct pid_namespace *ns) 208 { 209 struct vfsmount *mnt; 210 211 mnt = kern_mount_data(&proc_fs_type, ns); 212 if (IS_ERR(mnt)) 213 return PTR_ERR(mnt); 214 215 ns->proc_mnt = mnt; 216 return 0; 217 } 218 219 void pid_ns_release_proc(struct pid_namespace *ns) 220 { 221 mntput(ns->proc_mnt); 222 } 223