fs/proc/proc_net.c

   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 #include <linux/errno.h>
  12 #include <linux/time.h>
  13 #include <linux/proc_fs.h>
  14 #include <linux/stat.h>
  15 #include <linux/slab.h>
  16 #include <linux/init.h>
  17 #include <linux/sched.h>
  18 #include <linux/sched/task.h>
  19 #include <linux/module.h>
  20 #include <linux/bitops.h>
  21 #include <linux/mount.h>
  22 #include <linux/nsproxy.h>
  23 #include <linux/uidgid.h>
  24 #include <net/net_namespace.h>
  25 #include <linux/seq_file.h>
  26
  27 #include "internal.h"
  28
  29 static inline struct net *PDE_NET(struct proc_dir_entry *pde)
  30 {
  31         return pde->parent->data;
  32 }
  33
  34 static struct net *get_proc_net(const struct inode *inode)
  35 {
  36         return maybe_get_net(PDE_NET(PDE(inode)));
  37 }
  38
  39 static int seq_open_net(struct inode *inode, struct file *file)
  40 {
  41         unsigned int state_size = PDE(inode)->state_size;
  42         struct seq_net_private *p;
  43         struct net *net;
  44
  45         WARN_ON_ONCE(state_size < sizeof(*p));
  46
  47         if (file->f_mode & FMODE_WRITE && !PDE(inode)->write)
  48                 return -EACCES;
  49
  50         net = get_proc_net(inode);
  51         if (!net)
  52                 return -ENXIO;
  53
  54         p = __seq_open_private(file, PDE(inode)->seq_ops, state_size);
  55         if (!p) {
  56                 put_net(net);
  57                 return -ENOMEM;
  58         }
  59 #ifdef CONFIG_NET_NS
  60         p->net = net;
  61         netns_tracker_alloc(net, &p->ns_tracker, GFP_KERNEL);
  62 #endif
  63         return 0;
  64 }
  65
  66 static void seq_file_net_put_net(struct seq_file *seq)
  67 {
  68 #ifdef CONFIG_NET_NS
  69         struct seq_net_private *priv = seq->private;
  70
  71         put_net_track(priv->net, &priv->ns_tracker);
  72 #else
  73         put_net(&init_net);
  74 #endif
  75 }
  76
  77 static int seq_release_net(struct inode *ino, struct file *f)
  78 {
  79         struct seq_file *seq = f->private_data;
  80
  81         seq_file_net_put_net(seq);
  82         seq_release_private(ino, f);
  83         return 0;
  84 }
  85
  86 static const struct proc_ops proc_net_seq_ops = {
  87         .proc_open      = seq_open_net,
  88         .proc_read      = seq_read,
  89         .proc_write     = proc_simple_write,
  90         .proc_lseek     = seq_lseek,
  91         .proc_release   = seq_release_net,
  92 };
  93
  94 int bpf_iter_init_seq_net(void *priv_data, struct bpf_iter_aux_info *aux)
  95 {
  96 #ifdef CONFIG_NET_NS
  97         struct seq_net_private *p = priv_data;
  98
  99         p->net = get_net_track(current->nsproxy->net_ns, &p->ns_tracker,
 100                                GFP_KERNEL);
 101 #endif
 102         return 0;
 103 }
 104
 105 void bpf_iter_fini_seq_net(void *priv_data)
 106 {
 107 #ifdef CONFIG_NET_NS
 108         struct seq_net_private *p = priv_data;
 109
 110         put_net_track(p->net, &p->ns_tracker);
 111 #endif
 112 }
 113
 114 struct proc_dir_entry *proc_create_net_data(const char *name, umode_t mode,
 115                 struct proc_dir_entry *parent, const struct seq_operations *ops,
 116                 unsigned int state_size, void *data)
 117 {
 118         struct proc_dir_entry *p;
 119
 120         p = proc_create_reg(name, mode, &parent, data);
 121         if (!p)
 122                 return NULL;
 123         pde_force_lookup(p);
 124         p->proc_ops = &proc_net_seq_ops;
 125         p->seq_ops = ops;
 126         p->state_size = state_size;
 127         return proc_register(parent, p);
 128 }
 129 EXPORT_SYMBOL_GPL(proc_create_net_data);
 130
 131 /**
 132  * proc_create_net_data_write - Create a writable net_ns-specific proc file
 133  * @name: The name of the file.
 134  * @mode: The file's access mode.
 135  * @parent: The parent directory in which to create.
 136  * @ops: The seq_file ops with which to read the file.
 137  * @write: The write method with which to 'modify' the file.
 138  * @data: Data for retrieval by pde_data().
 139  *
 140  * Create a network namespaced proc file in the @parent directory with the
 141  * specified @name and @mode that allows reading of a file that displays a
 142  * series of elements and also provides for the file accepting writes that have
 143  * some arbitrary effect.
 144  *
 145  * The functions in the @ops table are used to iterate over items to be
 146  * presented and extract the readable content using the seq_file interface.
 147  *
 148  * The @write function is called with the data copied into a kernel space
 149  * scratch buffer and has a NUL appended for convenience.  The buffer may be
 150  * modified by the @write function.  @write should return 0 on success.
 151  *
 152  * The @data value is accessible from the @show and @write functions by calling
 153  * pde_data() on the file inode.  The network namespace must be accessed by
 154  * calling seq_file_net() on the seq_file struct.
 155  */
 156 struct proc_dir_entry *proc_create_net_data_write(const char *name, umode_t mode,
 157                                                   struct proc_dir_entry *parent,
 158                                                   const struct seq_operations *ops,
 159                                                   proc_write_t write,
 160                                                   unsigned int state_size, void *data)
 161 {
 162         struct proc_dir_entry *p;
 163
 164         p = proc_create_reg(name, mode, &parent, data);
 165         if (!p)
 166                 return NULL;
 167         pde_force_lookup(p);
 168         p->proc_ops = &proc_net_seq_ops;
 169         p->seq_ops = ops;
 170         p->state_size = state_size;
 171         p->write = write;
 172         return proc_register(parent, p);
 173 }
 174 EXPORT_SYMBOL_GPL(proc_create_net_data_write);
 175
 176 static int single_open_net(struct inode *inode, struct file *file)
 177 {
 178         struct proc_dir_entry *de = PDE(inode);
 179         struct net *net;
 180         int err;
 181
 182         net = get_proc_net(inode);
 183         if (!net)
 184                 return -ENXIO;
 185
 186         err = single_open(file, de->single_show, net);
 187         if (err)
 188                 put_net(net);
 189         return err;
 190 }
 191
 192 static int single_release_net(struct inode *ino, struct file *f)
 193 {
 194         struct seq_file *seq = f->private_data;
 195         put_net(seq->private);
 196         return single_release(ino, f);
 197 }
 198
 199 static const struct proc_ops proc_net_single_ops = {
 200         .proc_open      = single_open_net,
 201         .proc_read      = seq_read,
 202         .proc_write     = proc_simple_write,
 203         .proc_lseek     = seq_lseek,
 204         .proc_release   = single_release_net,
 205 };
 206
 207 struct proc_dir_entry *proc_create_net_single(const char *name, umode_t mode,
 208                 struct proc_dir_entry *parent,
 209                 int (*show)(struct seq_file *, void *), void *data)
 210 {
 211         struct proc_dir_entry *p;
 212
 213         p = proc_create_reg(name, mode, &parent, data);
 214         if (!p)
 215                 return NULL;
 216         pde_force_lookup(p);
 217         p->proc_ops = &proc_net_single_ops;
 218         p->single_show = show;
 219         return proc_register(parent, p);
 220 }
 221 EXPORT_SYMBOL_GPL(proc_create_net_single);
 222
 223 /**
 224  * proc_create_net_single_write - Create a writable net_ns-specific proc file
 225  * @name: The name of the file.
 226  * @mode: The file's access mode.
 227  * @parent: The parent directory in which to create.
 228  * @show: The seqfile show method with which to read the file.
 229  * @write: The write method with which to 'modify' the file.
 230  * @data: Data for retrieval by pde_data().
 231  *
 232  * Create a network-namespaced proc file in the @parent directory with the
 233  * specified @name and @mode that allows reading of a file that displays a
 234  * single element rather than a series and also provides for the file accepting
 235  * writes that have some arbitrary effect.
 236  *
 237  * The @show function is called to extract the readable content via the
 238  * seq_file interface.
 239  *
 240  * The @write function is called with the data copied into a kernel space
 241  * scratch buffer and has a NUL appended for convenience.  The buffer may be
 242  * modified by the @write function.  @write should return 0 on success.
 243  *
 244  * The @data value is accessible from the @show and @write functions by calling
 245  * pde_data() on the file inode.  The network namespace must be accessed by
 246  * calling seq_file_single_net() on the seq_file struct.
 247  */
 248 struct proc_dir_entry *proc_create_net_single_write(const char *name, umode_t mode,
 249                                                     struct proc_dir_entry *parent,
 250                                                     int (*show)(struct seq_file *, void *),
 251                                                     proc_write_t write,
 252                                                     void *data)
 253 {
 254         struct proc_dir_entry *p;
 255
 256         p = proc_create_reg(name, mode, &parent, data);
 257         if (!p)
 258                 return NULL;
 259         pde_force_lookup(p);
 260         p->proc_ops = &proc_net_single_ops;
 261         p->single_show = show;
 262         p->write = write;
 263         return proc_register(parent, p);
 264 }
 265 EXPORT_SYMBOL_GPL(proc_create_net_single_write);
 266
 267 static struct net *get_proc_task_net(struct inode *dir)
 268 {
 269         struct task_struct *task;
 270         struct nsproxy *ns;
 271         struct net *net = NULL;
 272
 273         rcu_read_lock();
 274         task = pid_task(proc_pid(dir), PIDTYPE_PID);
 275         if (task != NULL) {
 276                 task_lock(task);
 277                 ns = task->nsproxy;
 278                 if (ns != NULL)
 279                         net = get_net(ns->net_ns);
 280                 task_unlock(task);
 281         }
 282         rcu_read_unlock();
 283
 284         return net;
 285 }
 286
 287 static struct dentry *proc_tgid_net_lookup(struct inode *dir,
 288                 struct dentry *dentry, unsigned int flags)
 289 {
 290         struct dentry *de;
 291         struct net *net;
 292
 293         de = ERR_PTR(-ENOENT);
 294         net = get_proc_task_net(dir);
 295         if (net != NULL) {
 296                 de = proc_lookup_de(dir, dentry, net->proc_net);
 297                 put_net(net);
 298         }
 299         return de;
 300 }
 301
 302 static int proc_tgid_net_getattr(struct user_namespace *mnt_userns,
 303                                  const struct path *path, struct kstat *stat,
 304                                  u32 request_mask, unsigned int query_flags)
 305 {
 306         struct inode *inode = d_inode(path->dentry);
 307         struct net *net;
 308
 309         net = get_proc_task_net(inode);
 310
 311         generic_fillattr(&init_user_ns, inode, stat);
 312
 313         if (net != NULL) {
 314                 stat->nlink = net->proc_net->nlink;
 315                 put_net(net);
 316         }
 317
 318         return 0;
 319 }
 320
 321 const struct inode_operations proc_net_inode_operations = {
 322         .lookup         = proc_tgid_net_lookup,
 323         .getattr        = proc_tgid_net_getattr,
 324 };
 325
 326 static int proc_tgid_net_readdir(struct file *file, struct dir_context *ctx)
 327 {
 328         int ret;
 329         struct net *net;
 330
 331         ret = -EINVAL;
 332         net = get_proc_task_net(file_inode(file));
 333         if (net != NULL) {
 334                 ret = proc_readdir_de(file, ctx, net->proc_net);
 335                 put_net(net);
 336         }
 337         return ret;
 338 }
 339
 340 const struct file_operations proc_net_operations = {
 341         .llseek         = generic_file_llseek,
 342         .read           = generic_read_dir,
 343         .iterate_shared = proc_tgid_net_readdir,
 344 };
 345
 346 static __net_init int proc_net_ns_init(struct net *net)
 347 {
 348         struct proc_dir_entry *netd, *net_statd;
 349         kuid_t uid;
 350         kgid_t gid;
 351         int err;
 352
 353         /*
 354          * This PDE acts only as an anchor for /proc/${pid}/net hierarchy.
 355          * Corresponding inode (PDE(inode) == net->proc_net) is never
 356          * instantiated therefore blanket zeroing is fine.
 357          * net->proc_net_stat inode is instantiated normally.
 358          */
 359         err = -ENOMEM;
 360         netd = kmem_cache_zalloc(proc_dir_entry_cache, GFP_KERNEL);
 361         if (!netd)
 362                 goto out;
 363
 364         netd->subdir = RB_ROOT;
 365         netd->data = net;
 366         netd->nlink = 2;
 367         netd->namelen = 3;
 368         netd->parent = &proc_root;
 369         netd->name = netd->inline_name;
 370         memcpy(netd->name, "net", 4);
 371
 372         uid = make_kuid(net->user_ns, 0);
 373         if (!uid_valid(uid))
 374                 uid = netd->uid;
 375
 376         gid = make_kgid(net->user_ns, 0);
 377         if (!gid_valid(gid))
 378                 gid = netd->gid;
 379
 380         proc_set_user(netd, uid, gid);
 381
 382         /* Seed dentry revalidation for /proc/${pid}/net */
 383         pde_force_lookup(netd);
 384
 385         err = -EEXIST;
 386         net_statd = proc_net_mkdir(net, "stat", netd);
 387         if (!net_statd)
 388                 goto free_net;
 389
 390         net->proc_net = netd;
 391         net->proc_net_stat = net_statd;
 392         return 0;
 393
 394 free_net:
 395         pde_free(netd);
 396 out:
 397         return err;
 398 }
 399
 400 static __net_exit void proc_net_ns_exit(struct net *net)
 401 {
 402         remove_proc_entry("stat", net->proc_net);
 403         pde_free(net->proc_net);
 404 }
 405
 406 static struct pernet_operations __net_initdata proc_net_ns_ops = {
 407         .init = proc_net_ns_init,
 408         .exit = proc_net_ns_exit,
 409 };
 410
 411 int __init proc_net_init(void)
 412 {
 413         proc_symlink("net", NULL, "self/net");
 414
 415         return register_pernet_subsys(&proc_net_ns_ops);
 416 }