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![Christian Brauner](/assets/img/avatar_default.png)
Extend some inode methods with an additional user namespace argument. A filesystem that is aware of idmapped mounts will receive the user namespace the mount has been marked with. This can be used for additional permission checking and also to enable filesystems to translate between uids and gids if they need to. We have implemented all relevant helpers in earlier patches. As requested we simply extend the exisiting inode method instead of introducing new ones. This is a little more code churn but it's mostly mechanical and doesnt't leave us with additional inode methods. Link: https://lore.kernel.org/r/20210121131959.646623-25-christian.brauner@ubuntu.com Cc: Christoph Hellwig <hch@lst.de> Cc: David Howells <dhowells@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: linux-fsdevel@vger.kernel.org Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
397 lines
9.7 KiB
C
397 lines
9.7 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* linux/fs/proc/net.c
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*
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* Copyright (C) 2007
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*
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* Author: Eric Biederman <ebiederm@xmission.com>
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*
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* proc net directory handling functions
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*/
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#include <linux/uaccess.h>
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#include <linux/errno.h>
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#include <linux/time.h>
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#include <linux/proc_fs.h>
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#include <linux/stat.h>
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#include <linux/slab.h>
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#include <linux/init.h>
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#include <linux/sched.h>
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#include <linux/sched/task.h>
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#include <linux/module.h>
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#include <linux/bitops.h>
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#include <linux/mount.h>
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#include <linux/nsproxy.h>
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#include <linux/uidgid.h>
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#include <net/net_namespace.h>
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#include <linux/seq_file.h>
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#include "internal.h"
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static inline struct net *PDE_NET(struct proc_dir_entry *pde)
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{
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return pde->parent->data;
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}
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static struct net *get_proc_net(const struct inode *inode)
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{
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return maybe_get_net(PDE_NET(PDE(inode)));
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}
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static int seq_open_net(struct inode *inode, struct file *file)
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{
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unsigned int state_size = PDE(inode)->state_size;
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struct seq_net_private *p;
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struct net *net;
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WARN_ON_ONCE(state_size < sizeof(*p));
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if (file->f_mode & FMODE_WRITE && !PDE(inode)->write)
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return -EACCES;
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net = get_proc_net(inode);
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if (!net)
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return -ENXIO;
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p = __seq_open_private(file, PDE(inode)->seq_ops, state_size);
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if (!p) {
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put_net(net);
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return -ENOMEM;
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}
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#ifdef CONFIG_NET_NS
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p->net = net;
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#endif
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return 0;
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}
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static int seq_release_net(struct inode *ino, struct file *f)
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{
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struct seq_file *seq = f->private_data;
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put_net(seq_file_net(seq));
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seq_release_private(ino, f);
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return 0;
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}
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static const struct proc_ops proc_net_seq_ops = {
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.proc_open = seq_open_net,
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.proc_read = seq_read,
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.proc_write = proc_simple_write,
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.proc_lseek = seq_lseek,
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.proc_release = seq_release_net,
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};
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int bpf_iter_init_seq_net(void *priv_data, struct bpf_iter_aux_info *aux)
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{
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#ifdef CONFIG_NET_NS
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struct seq_net_private *p = priv_data;
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p->net = get_net(current->nsproxy->net_ns);
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#endif
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return 0;
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}
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void bpf_iter_fini_seq_net(void *priv_data)
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{
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#ifdef CONFIG_NET_NS
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struct seq_net_private *p = priv_data;
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put_net(p->net);
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#endif
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}
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struct proc_dir_entry *proc_create_net_data(const char *name, umode_t mode,
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struct proc_dir_entry *parent, const struct seq_operations *ops,
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unsigned int state_size, void *data)
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{
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struct proc_dir_entry *p;
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p = proc_create_reg(name, mode, &parent, data);
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if (!p)
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return NULL;
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pde_force_lookup(p);
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p->proc_ops = &proc_net_seq_ops;
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p->seq_ops = ops;
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p->state_size = state_size;
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return proc_register(parent, p);
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}
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EXPORT_SYMBOL_GPL(proc_create_net_data);
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/**
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* proc_create_net_data_write - Create a writable net_ns-specific proc file
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* @name: The name of the file.
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* @mode: The file's access mode.
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* @parent: The parent directory in which to create.
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* @ops: The seq_file ops with which to read the file.
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* @write: The write method with which to 'modify' the file.
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* @data: Data for retrieval by PDE_DATA().
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*
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* Create a network namespaced proc file in the @parent directory with the
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* specified @name and @mode that allows reading of a file that displays a
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* series of elements and also provides for the file accepting writes that have
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* some arbitrary effect.
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*
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* The functions in the @ops table are used to iterate over items to be
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* presented and extract the readable content using the seq_file interface.
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*
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* The @write function is called with the data copied into a kernel space
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* scratch buffer and has a NUL appended for convenience. The buffer may be
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* modified by the @write function. @write should return 0 on success.
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*
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* The @data value is accessible from the @show and @write functions by calling
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* PDE_DATA() on the file inode. The network namespace must be accessed by
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* calling seq_file_net() on the seq_file struct.
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*/
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struct proc_dir_entry *proc_create_net_data_write(const char *name, umode_t mode,
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struct proc_dir_entry *parent,
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const struct seq_operations *ops,
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proc_write_t write,
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unsigned int state_size, void *data)
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{
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struct proc_dir_entry *p;
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p = proc_create_reg(name, mode, &parent, data);
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if (!p)
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return NULL;
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pde_force_lookup(p);
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p->proc_ops = &proc_net_seq_ops;
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p->seq_ops = ops;
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p->state_size = state_size;
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p->write = write;
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return proc_register(parent, p);
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}
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EXPORT_SYMBOL_GPL(proc_create_net_data_write);
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static int single_open_net(struct inode *inode, struct file *file)
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{
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struct proc_dir_entry *de = PDE(inode);
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struct net *net;
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int err;
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net = get_proc_net(inode);
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if (!net)
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return -ENXIO;
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err = single_open(file, de->single_show, net);
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if (err)
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put_net(net);
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return err;
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}
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static int single_release_net(struct inode *ino, struct file *f)
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{
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struct seq_file *seq = f->private_data;
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put_net(seq->private);
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return single_release(ino, f);
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}
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static const struct proc_ops proc_net_single_ops = {
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.proc_open = single_open_net,
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.proc_read = seq_read,
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.proc_write = proc_simple_write,
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.proc_lseek = seq_lseek,
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.proc_release = single_release_net,
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};
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struct proc_dir_entry *proc_create_net_single(const char *name, umode_t mode,
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struct proc_dir_entry *parent,
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int (*show)(struct seq_file *, void *), void *data)
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{
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struct proc_dir_entry *p;
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p = proc_create_reg(name, mode, &parent, data);
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if (!p)
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return NULL;
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pde_force_lookup(p);
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p->proc_ops = &proc_net_single_ops;
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p->single_show = show;
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return proc_register(parent, p);
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}
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EXPORT_SYMBOL_GPL(proc_create_net_single);
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/**
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* proc_create_net_single_write - Create a writable net_ns-specific proc file
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* @name: The name of the file.
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* @mode: The file's access mode.
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* @parent: The parent directory in which to create.
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* @show: The seqfile show method with which to read the file.
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* @write: The write method with which to 'modify' the file.
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* @data: Data for retrieval by PDE_DATA().
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*
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* Create a network-namespaced proc file in the @parent directory with the
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* specified @name and @mode that allows reading of a file that displays a
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* single element rather than a series and also provides for the file accepting
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* writes that have some arbitrary effect.
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*
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* The @show function is called to extract the readable content via the
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* seq_file interface.
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*
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* The @write function is called with the data copied into a kernel space
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* scratch buffer and has a NUL appended for convenience. The buffer may be
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* modified by the @write function. @write should return 0 on success.
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*
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* The @data value is accessible from the @show and @write functions by calling
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* PDE_DATA() on the file inode. The network namespace must be accessed by
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* calling seq_file_single_net() on the seq_file struct.
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*/
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struct proc_dir_entry *proc_create_net_single_write(const char *name, umode_t mode,
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struct proc_dir_entry *parent,
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int (*show)(struct seq_file *, void *),
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proc_write_t write,
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void *data)
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{
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struct proc_dir_entry *p;
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p = proc_create_reg(name, mode, &parent, data);
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if (!p)
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return NULL;
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pde_force_lookup(p);
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p->proc_ops = &proc_net_single_ops;
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p->single_show = show;
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p->write = write;
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return proc_register(parent, p);
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}
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EXPORT_SYMBOL_GPL(proc_create_net_single_write);
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static struct net *get_proc_task_net(struct inode *dir)
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{
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struct task_struct *task;
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struct nsproxy *ns;
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struct net *net = NULL;
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rcu_read_lock();
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task = pid_task(proc_pid(dir), PIDTYPE_PID);
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if (task != NULL) {
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task_lock(task);
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ns = task->nsproxy;
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if (ns != NULL)
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net = get_net(ns->net_ns);
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task_unlock(task);
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}
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rcu_read_unlock();
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return net;
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}
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static struct dentry *proc_tgid_net_lookup(struct inode *dir,
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struct dentry *dentry, unsigned int flags)
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{
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struct dentry *de;
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struct net *net;
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de = ERR_PTR(-ENOENT);
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net = get_proc_task_net(dir);
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if (net != NULL) {
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de = proc_lookup_de(dir, dentry, net->proc_net);
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put_net(net);
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}
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return de;
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}
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static int proc_tgid_net_getattr(struct user_namespace *mnt_userns,
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const struct path *path, struct kstat *stat,
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u32 request_mask, unsigned int query_flags)
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{
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struct inode *inode = d_inode(path->dentry);
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struct net *net;
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net = get_proc_task_net(inode);
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generic_fillattr(&init_user_ns, inode, stat);
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if (net != NULL) {
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stat->nlink = net->proc_net->nlink;
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put_net(net);
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}
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return 0;
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}
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const struct inode_operations proc_net_inode_operations = {
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.lookup = proc_tgid_net_lookup,
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.getattr = proc_tgid_net_getattr,
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};
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static int proc_tgid_net_readdir(struct file *file, struct dir_context *ctx)
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{
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int ret;
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struct net *net;
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ret = -EINVAL;
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net = get_proc_task_net(file_inode(file));
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if (net != NULL) {
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ret = proc_readdir_de(file, ctx, net->proc_net);
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put_net(net);
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}
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return ret;
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}
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const struct file_operations proc_net_operations = {
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.llseek = generic_file_llseek,
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.read = generic_read_dir,
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.iterate_shared = proc_tgid_net_readdir,
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};
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static __net_init int proc_net_ns_init(struct net *net)
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{
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struct proc_dir_entry *netd, *net_statd;
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kuid_t uid;
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kgid_t gid;
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int err;
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err = -ENOMEM;
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netd = kmem_cache_zalloc(proc_dir_entry_cache, GFP_KERNEL);
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if (!netd)
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goto out;
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netd->subdir = RB_ROOT;
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netd->data = net;
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netd->nlink = 2;
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netd->namelen = 3;
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netd->parent = &proc_root;
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netd->name = netd->inline_name;
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memcpy(netd->name, "net", 4);
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uid = make_kuid(net->user_ns, 0);
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if (!uid_valid(uid))
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uid = netd->uid;
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gid = make_kgid(net->user_ns, 0);
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if (!gid_valid(gid))
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gid = netd->gid;
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proc_set_user(netd, uid, gid);
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err = -EEXIST;
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net_statd = proc_net_mkdir(net, "stat", netd);
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if (!net_statd)
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goto free_net;
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net->proc_net = netd;
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net->proc_net_stat = net_statd;
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return 0;
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free_net:
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pde_free(netd);
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out:
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return err;
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}
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static __net_exit void proc_net_ns_exit(struct net *net)
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{
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remove_proc_entry("stat", net->proc_net);
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pde_free(net->proc_net);
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}
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static struct pernet_operations __net_initdata proc_net_ns_ops = {
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.init = proc_net_ns_init,
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.exit = proc_net_ns_exit,
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};
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int __init proc_net_init(void)
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{
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proc_symlink("net", NULL, "self/net");
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return register_pernet_subsys(&proc_net_ns_ops);
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}
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