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Linux/fs/proc/root.c

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  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 

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