root/fs/proc/proc_net.c

DEFINITIONS

1. PDE_NET
2. get_proc_net
3. proc_net_d_revalidate
4. pde_force_lookup
5. seq_open_net
6. seq_release_net
7. proc_create_net_data
8. proc_create_net_data_write
9. single_open_net
10. single_release_net
11. proc_create_net_single
12. proc_create_net_single_write
13. get_proc_task_net
14. proc_tgid_net_lookup
15. proc_tgid_net_getattr
16. proc_tgid_net_readdir
17. proc_net_ns_init
18. proc_net_ns_exit
19. proc_net_init

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  linux/fs/proc/net.c
   4  *
   5  *  Copyright (C) 2007
   6  *
   7  *  Author: Eric Biederman <ebiederm@xmission.com>
   8  *
   9  *  proc net directory handling functions
  10  */
  11 
  12 #include <linux/uaccess.h>
  13 
  14 #include <linux/errno.h>
  15 #include <linux/time.h>
  16 #include <linux/proc_fs.h>
  17 #include <linux/stat.h>
  18 #include <linux/slab.h>
  19 #include <linux/init.h>
  20 #include <linux/sched.h>
  21 #include <linux/sched/task.h>
  22 #include <linux/module.h>
  23 #include <linux/bitops.h>
  24 #include <linux/mount.h>
  25 #include <linux/nsproxy.h>
  26 #include <linux/uidgid.h>
  27 #include <net/net_namespace.h>
  28 #include <linux/seq_file.h>
  29 
  30 #include "internal.h"
  31 
  32 static inline struct net *PDE_NET(struct proc_dir_entry *pde)
  33 {
  34         return pde->parent->data;
  35 }
  36 
  37 static struct net *get_proc_net(const struct inode *inode)
  38 {
  39         return maybe_get_net(PDE_NET(PDE(inode)));
  40 }
  41 
  42 static int proc_net_d_revalidate(struct dentry *dentry, unsigned int flags)
  43 {
  44         return 0;
  45 }
  46 
  47 static const struct dentry_operations proc_net_dentry_ops = {
  48         .d_revalidate   = proc_net_d_revalidate,
  49         .d_delete       = always_delete_dentry,
  50 };
  51 
  52 static void pde_force_lookup(struct proc_dir_entry *pde)
  53 {
  54         /* /proc/net/ entries can be changed under us by setns(CLONE_NEWNET) */
  55         pde->proc_dops = &proc_net_dentry_ops;
  56 }
  57 
  58 static int seq_open_net(struct inode *inode, struct file *file)
  59 {
  60         unsigned int state_size = PDE(inode)->state_size;
  61         struct seq_net_private *p;
  62         struct net *net;
  63 
  64         WARN_ON_ONCE(state_size < sizeof(*p));
  65 
  66         if (file->f_mode & FMODE_WRITE && !PDE(inode)->write)
  67                 return -EACCES;
  68 
  69         net = get_proc_net(inode);
  70         if (!net)
  71                 return -ENXIO;
  72 
  73         p = __seq_open_private(file, PDE(inode)->seq_ops, state_size);
  74         if (!p) {
  75                 put_net(net);
  76                 return -ENOMEM;
  77         }
  78 #ifdef CONFIG_NET_NS
  79         p->net = net;
  80 #endif
  81         return 0;
  82 }
  83 
  84 static int seq_release_net(struct inode *ino, struct file *f)
  85 {
  86         struct seq_file *seq = f->private_data;
  87 
  88         put_net(seq_file_net(seq));
  89         seq_release_private(ino, f);
  90         return 0;
  91 }
  92 
  93 static const struct file_operations proc_net_seq_fops = {
  94         .open           = seq_open_net,
  95         .read           = seq_read,
  96         .write          = proc_simple_write,
  97         .llseek         = seq_lseek,
  98         .release        = seq_release_net,
  99 };
 100 
 101 struct proc_dir_entry *proc_create_net_data(const char *name, umode_t mode,
 102                 struct proc_dir_entry *parent, const struct seq_operations *ops,
 103                 unsigned int state_size, void *data)
 104 {
 105         struct proc_dir_entry *p;
 106 
 107         p = proc_create_reg(name, mode, &parent, data);
 108         if (!p)
 109                 return NULL;
 110         pde_force_lookup(p);
 111         p->proc_fops = &proc_net_seq_fops;
 112         p->seq_ops = ops;
 113         p->state_size = state_size;
 114         return proc_register(parent, p);
 115 }
 116 EXPORT_SYMBOL_GPL(proc_create_net_data);
 117 
 118 /**
 119  * proc_create_net_data_write - Create a writable net_ns-specific proc file
 120  * @name: The name of the file.
 121  * @mode: The file's access mode.
 122  * @parent: The parent directory in which to create.
 123  * @ops: The seq_file ops with which to read the file.
 124  * @write: The write method which which to 'modify' the file.
 125  * @data: Data for retrieval by PDE_DATA().
 126  *
 127  * Create a network namespaced proc file in the @parent directory with the
 128  * specified @name and @mode that allows reading of a file that displays a
 129  * series of elements and also provides for the file accepting writes that have
 130  * some arbitrary effect.
 131  *
 132  * The functions in the @ops table are used to iterate over items to be
 133  * presented and extract the readable content using the seq_file interface.
 134  *
 135  * The @write function is called with the data copied into a kernel space
 136  * scratch buffer and has a NUL appended for convenience.  The buffer may be
 137  * modified by the @write function.  @write should return 0 on success.
 138  *
 139  * The @data value is accessible from the @show and @write functions by calling
 140  * PDE_DATA() on the file inode.  The network namespace must be accessed by
 141  * calling seq_file_net() on the seq_file struct.
 142  */
 143 struct proc_dir_entry *proc_create_net_data_write(const char *name, umode_t mode,
 144                                                   struct proc_dir_entry *parent,
 145                                                   const struct seq_operations *ops,
 146                                                   proc_write_t write,
 147                                                   unsigned int state_size, void *data)
 148 {
 149         struct proc_dir_entry *p;
 150 
 151         p = proc_create_reg(name, mode, &parent, data);
 152         if (!p)
 153                 return NULL;
 154         pde_force_lookup(p);
 155         p->proc_fops = &proc_net_seq_fops;
 156         p->seq_ops = ops;
 157         p->state_size = state_size;
 158         p->write = write;
 159         return proc_register(parent, p);
 160 }
 161 EXPORT_SYMBOL_GPL(proc_create_net_data_write);
 162 
 163 static int single_open_net(struct inode *inode, struct file *file)
 164 {
 165         struct proc_dir_entry *de = PDE(inode);
 166         struct net *net;
 167         int err;
 168 
 169         net = get_proc_net(inode);
 170         if (!net)
 171                 return -ENXIO;
 172 
 173         err = single_open(file, de->single_show, net);
 174         if (err)
 175                 put_net(net);
 176         return err;
 177 }
 178 
 179 static int single_release_net(struct inode *ino, struct file *f)
 180 {
 181         struct seq_file *seq = f->private_data;
 182         put_net(seq->private);
 183         return single_release(ino, f);
 184 }
 185 
 186 static const struct file_operations proc_net_single_fops = {
 187         .open           = single_open_net,
 188         .read           = seq_read,
 189         .write          = proc_simple_write,
 190         .llseek         = seq_lseek,
 191         .release        = single_release_net,
 192 };
 193 
 194 struct proc_dir_entry *proc_create_net_single(const char *name, umode_t mode,
 195                 struct proc_dir_entry *parent,
 196                 int (*show)(struct seq_file *, void *), void *data)
 197 {
 198         struct proc_dir_entry *p;
 199 
 200         p = proc_create_reg(name, mode, &parent, data);
 201         if (!p)
 202                 return NULL;
 203         pde_force_lookup(p);
 204         p->proc_fops = &proc_net_single_fops;
 205         p->single_show = show;
 206         return proc_register(parent, p);
 207 }
 208 EXPORT_SYMBOL_GPL(proc_create_net_single);
 209 
 210 /**
 211  * proc_create_net_single_write - Create a writable net_ns-specific proc file
 212  * @name: The name of the file.
 213  * @mode: The file's access mode.
 214  * @parent: The parent directory in which to create.
 215  * @show: The seqfile show method with which to read the file.
 216  * @write: The write method which which to 'modify' the file.
 217  * @data: Data for retrieval by PDE_DATA().
 218  *
 219  * Create a network-namespaced proc file in the @parent directory with the
 220  * specified @name and @mode that allows reading of a file that displays a
 221  * single element rather than a series and also provides for the file accepting
 222  * writes that have some arbitrary effect.
 223  *
 224  * The @show function is called to extract the readable content via the
 225  * seq_file interface.
 226  *
 227  * The @write function is called with the data copied into a kernel space
 228  * scratch buffer and has a NUL appended for convenience.  The buffer may be
 229  * modified by the @write function.  @write should return 0 on success.
 230  *
 231  * The @data value is accessible from the @show and @write functions by calling
 232  * PDE_DATA() on the file inode.  The network namespace must be accessed by
 233  * calling seq_file_single_net() on the seq_file struct.
 234  */
 235 struct proc_dir_entry *proc_create_net_single_write(const char *name, umode_t mode,
 236                                                     struct proc_dir_entry *parent,
 237                                                     int (*show)(struct seq_file *, void *),
 238                                                     proc_write_t write,
 239                                                     void *data)
 240 {
 241         struct proc_dir_entry *p;
 242 
 243         p = proc_create_reg(name, mode, &parent, data);
 244         if (!p)
 245                 return NULL;
 246         pde_force_lookup(p);
 247         p->proc_fops = &proc_net_single_fops;
 248         p->single_show = show;
 249         p->write = write;
 250         return proc_register(parent, p);
 251 }
 252 EXPORT_SYMBOL_GPL(proc_create_net_single_write);
 253 
 254 static struct net *get_proc_task_net(struct inode *dir)
 255 {
 256         struct task_struct *task;
 257         struct nsproxy *ns;
 258         struct net *net = NULL;
 259 
 260         rcu_read_lock();
 261         task = pid_task(proc_pid(dir), PIDTYPE_PID);
 262         if (task != NULL) {
 263                 task_lock(task);
 264                 ns = task->nsproxy;
 265                 if (ns != NULL)
 266                         net = get_net(ns->net_ns);
 267                 task_unlock(task);
 268         }
 269         rcu_read_unlock();
 270 
 271         return net;
 272 }
 273 
 274 static struct dentry *proc_tgid_net_lookup(struct inode *dir,
 275                 struct dentry *dentry, unsigned int flags)
 276 {
 277         struct dentry *de;
 278         struct net *net;
 279 
 280         de = ERR_PTR(-ENOENT);
 281         net = get_proc_task_net(dir);
 282         if (net != NULL) {
 283                 de = proc_lookup_de(dir, dentry, net->proc_net);
 284                 put_net(net);
 285         }
 286         return de;
 287 }
 288 
 289 static int proc_tgid_net_getattr(const struct path *path, struct kstat *stat,
 290                                  u32 request_mask, unsigned int query_flags)
 291 {
 292         struct inode *inode = d_inode(path->dentry);
 293         struct net *net;
 294 
 295         net = get_proc_task_net(inode);
 296 
 297         generic_fillattr(inode, stat);
 298 
 299         if (net != NULL) {
 300                 stat->nlink = net->proc_net->nlink;
 301                 put_net(net);
 302         }
 303 
 304         return 0;
 305 }
 306 
 307 const struct inode_operations proc_net_inode_operations = {
 308         .lookup         = proc_tgid_net_lookup,
 309         .getattr        = proc_tgid_net_getattr,
 310 };
 311 
 312 static int proc_tgid_net_readdir(struct file *file, struct dir_context *ctx)
 313 {
 314         int ret;
 315         struct net *net;
 316 
 317         ret = -EINVAL;
 318         net = get_proc_task_net(file_inode(file));
 319         if (net != NULL) {
 320                 ret = proc_readdir_de(file, ctx, net->proc_net);
 321                 put_net(net);
 322         }
 323         return ret;
 324 }
 325 
 326 const struct file_operations proc_net_operations = {
 327         .llseek         = generic_file_llseek,
 328         .read           = generic_read_dir,
 329         .iterate_shared = proc_tgid_net_readdir,
 330 };
 331 
 332 static __net_init int proc_net_ns_init(struct net *net)
 333 {
 334         struct proc_dir_entry *netd, *net_statd;
 335         kuid_t uid;
 336         kgid_t gid;
 337         int err;
 338 
 339         err = -ENOMEM;
 340         netd = kmem_cache_zalloc(proc_dir_entry_cache, GFP_KERNEL);
 341         if (!netd)
 342                 goto out;
 343 
 344         netd->subdir = RB_ROOT;
 345         netd->data = net;
 346         netd->nlink = 2;
 347         netd->namelen = 3;
 348         netd->parent = &proc_root;
 349         netd->name = netd->inline_name;
 350         memcpy(netd->name, "net", 4);
 351 
 352         uid = make_kuid(net->user_ns, 0);
 353         if (!uid_valid(uid))
 354                 uid = netd->uid;
 355 
 356         gid = make_kgid(net->user_ns, 0);
 357         if (!gid_valid(gid))
 358                 gid = netd->gid;
 359 
 360         proc_set_user(netd, uid, gid);
 361 
 362         err = -EEXIST;
 363         net_statd = proc_net_mkdir(net, "stat", netd);
 364         if (!net_statd)
 365                 goto free_net;
 366 
 367         net->proc_net = netd;
 368         net->proc_net_stat = net_statd;
 369         return 0;
 370 
 371 free_net:
 372         pde_free(netd);
 373 out:
 374         return err;
 375 }
 376 
 377 static __net_exit void proc_net_ns_exit(struct net *net)
 378 {
 379         remove_proc_entry("stat", net->proc_net);
 380         pde_free(net->proc_net);
 381 }
 382 
 383 static struct pernet_operations __net_initdata proc_net_ns_ops = {
 384         .init = proc_net_ns_init,
 385         .exit = proc_net_ns_exit,
 386 };
 387 
 388 int __init proc_net_init(void)
 389 {
 390         proc_symlink("net", NULL, "self/net");
 391 
 392         return register_pernet_subsys(&proc_net_ns_ops);
 393 }