linux/fs/proc/proc_net.c
Alexey Dobriyan 1fde6f21d9 proc: fix /proc/net/* after setns(2)
/proc entries under /proc/net/* can't be cached into dcache because
setns(2) can change current net namespace.

[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: avoid vim miscolorization]
[adobriyan@gmail.com: write test, add dummy ->d_revalidate hook: necessary if /proc/net/* is pinned at setns time]
  Link: http://lkml.kernel.org/r/20190108192350.GA12034@avx2
Link: http://lkml.kernel.org/r/20190107162336.GA9239@avx2
Fixes: 1da4d377f9 ("proc: revalidate misc dentries")
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Reported-by: Mateusz Stępień <mateusz.stepien@netrounds.com>
Reported-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-02-01 15:46:22 -08:00

393 lines
9.7 KiB
C

/*
* linux/fs/proc/net.c
*
* Copyright (C) 2007
*
* Author: Eric Biederman <ebiederm@xmission.com>
*
* proc net directory handling functions
*/
#include <linux/uaccess.h>
#include <linux/errno.h>
#include <linux/time.h>
#include <linux/proc_fs.h>
#include <linux/stat.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/sched/task.h>
#include <linux/module.h>
#include <linux/bitops.h>
#include <linux/mount.h>
#include <linux/nsproxy.h>
#include <linux/uidgid.h>
#include <net/net_namespace.h>
#include <linux/seq_file.h>
#include "internal.h"
static inline struct net *PDE_NET(struct proc_dir_entry *pde)
{
return pde->parent->data;
}
static struct net *get_proc_net(const struct inode *inode)
{
return maybe_get_net(PDE_NET(PDE(inode)));
}
static int proc_net_d_revalidate(struct dentry *dentry, unsigned int flags)
{
return 0;
}
static const struct dentry_operations proc_net_dentry_ops = {
.d_revalidate = proc_net_d_revalidate,
.d_delete = always_delete_dentry,
};
static void pde_force_lookup(struct proc_dir_entry *pde)
{
/* /proc/net/ entries can be changed under us by setns(CLONE_NEWNET) */
pde->proc_dops = &proc_net_dentry_ops;
}
static int seq_open_net(struct inode *inode, struct file *file)
{
unsigned int state_size = PDE(inode)->state_size;
struct seq_net_private *p;
struct net *net;
WARN_ON_ONCE(state_size < sizeof(*p));
if (file->f_mode & FMODE_WRITE && !PDE(inode)->write)
return -EACCES;
net = get_proc_net(inode);
if (!net)
return -ENXIO;
p = __seq_open_private(file, PDE(inode)->seq_ops, state_size);
if (!p) {
put_net(net);
return -ENOMEM;
}
#ifdef CONFIG_NET_NS
p->net = net;
#endif
return 0;
}
static int seq_release_net(struct inode *ino, struct file *f)
{
struct seq_file *seq = f->private_data;
put_net(seq_file_net(seq));
seq_release_private(ino, f);
return 0;
}
static const struct file_operations proc_net_seq_fops = {
.open = seq_open_net,
.read = seq_read,
.write = proc_simple_write,
.llseek = seq_lseek,
.release = seq_release_net,
};
struct proc_dir_entry *proc_create_net_data(const char *name, umode_t mode,
struct proc_dir_entry *parent, const struct seq_operations *ops,
unsigned int state_size, void *data)
{
struct proc_dir_entry *p;
p = proc_create_reg(name, mode, &parent, data);
if (!p)
return NULL;
pde_force_lookup(p);
p->proc_fops = &proc_net_seq_fops;
p->seq_ops = ops;
p->state_size = state_size;
return proc_register(parent, p);
}
EXPORT_SYMBOL_GPL(proc_create_net_data);
/**
* proc_create_net_data_write - Create a writable net_ns-specific proc file
* @name: The name of the file.
* @mode: The file's access mode.
* @parent: The parent directory in which to create.
* @ops: The seq_file ops with which to read the file.
* @write: The write method which which to 'modify' the file.
* @data: Data for retrieval by PDE_DATA().
*
* Create a network namespaced proc file in the @parent directory with the
* specified @name and @mode that allows reading of a file that displays a
* series of elements and also provides for the file accepting writes that have
* some arbitrary effect.
*
* The functions in the @ops table are used to iterate over items to be
* presented and extract the readable content using the seq_file interface.
*
* The @write function is called with the data copied into a kernel space
* scratch buffer and has a NUL appended for convenience. The buffer may be
* modified by the @write function. @write should return 0 on success.
*
* The @data value is accessible from the @show and @write functions by calling
* PDE_DATA() on the file inode. The network namespace must be accessed by
* calling seq_file_net() on the seq_file struct.
*/
struct proc_dir_entry *proc_create_net_data_write(const char *name, umode_t mode,
struct proc_dir_entry *parent,
const struct seq_operations *ops,
proc_write_t write,
unsigned int state_size, void *data)
{
struct proc_dir_entry *p;
p = proc_create_reg(name, mode, &parent, data);
if (!p)
return NULL;
pde_force_lookup(p);
p->proc_fops = &proc_net_seq_fops;
p->seq_ops = ops;
p->state_size = state_size;
p->write = write;
return proc_register(parent, p);
}
EXPORT_SYMBOL_GPL(proc_create_net_data_write);
static int single_open_net(struct inode *inode, struct file *file)
{
struct proc_dir_entry *de = PDE(inode);
struct net *net;
int err;
net = get_proc_net(inode);
if (!net)
return -ENXIO;
err = single_open(file, de->single_show, net);
if (err)
put_net(net);
return err;
}
static int single_release_net(struct inode *ino, struct file *f)
{
struct seq_file *seq = f->private_data;
put_net(seq->private);
return single_release(ino, f);
}
static const struct file_operations proc_net_single_fops = {
.open = single_open_net,
.read = seq_read,
.write = proc_simple_write,
.llseek = seq_lseek,
.release = single_release_net,
};
struct proc_dir_entry *proc_create_net_single(const char *name, umode_t mode,
struct proc_dir_entry *parent,
int (*show)(struct seq_file *, void *), void *data)
{
struct proc_dir_entry *p;
p = proc_create_reg(name, mode, &parent, data);
if (!p)
return NULL;
pde_force_lookup(p);
p->proc_fops = &proc_net_single_fops;
p->single_show = show;
return proc_register(parent, p);
}
EXPORT_SYMBOL_GPL(proc_create_net_single);
/**
* proc_create_net_single_write - Create a writable net_ns-specific proc file
* @name: The name of the file.
* @mode: The file's access mode.
* @parent: The parent directory in which to create.
* @show: The seqfile show method with which to read the file.
* @write: The write method which which to 'modify' the file.
* @data: Data for retrieval by PDE_DATA().
*
* Create a network-namespaced proc file in the @parent directory with the
* specified @name and @mode that allows reading of a file that displays a
* single element rather than a series and also provides for the file accepting
* writes that have some arbitrary effect.
*
* The @show function is called to extract the readable content via the
* seq_file interface.
*
* The @write function is called with the data copied into a kernel space
* scratch buffer and has a NUL appended for convenience. The buffer may be
* modified by the @write function. @write should return 0 on success.
*
* The @data value is accessible from the @show and @write functions by calling
* PDE_DATA() on the file inode. The network namespace must be accessed by
* calling seq_file_single_net() on the seq_file struct.
*/
struct proc_dir_entry *proc_create_net_single_write(const char *name, umode_t mode,
struct proc_dir_entry *parent,
int (*show)(struct seq_file *, void *),
proc_write_t write,
void *data)
{
struct proc_dir_entry *p;
p = proc_create_reg(name, mode, &parent, data);
if (!p)
return NULL;
pde_force_lookup(p);
p->proc_fops = &proc_net_single_fops;
p->single_show = show;
p->write = write;
return proc_register(parent, p);
}
EXPORT_SYMBOL_GPL(proc_create_net_single_write);
static struct net *get_proc_task_net(struct inode *dir)
{
struct task_struct *task;
struct nsproxy *ns;
struct net *net = NULL;
rcu_read_lock();
task = pid_task(proc_pid(dir), PIDTYPE_PID);
if (task != NULL) {
task_lock(task);
ns = task->nsproxy;
if (ns != NULL)
net = get_net(ns->net_ns);
task_unlock(task);
}
rcu_read_unlock();
return net;
}
static struct dentry *proc_tgid_net_lookup(struct inode *dir,
struct dentry *dentry, unsigned int flags)
{
struct dentry *de;
struct net *net;
de = ERR_PTR(-ENOENT);
net = get_proc_task_net(dir);
if (net != NULL) {
de = proc_lookup_de(dir, dentry, net->proc_net);
put_net(net);
}
return de;
}
static int proc_tgid_net_getattr(const struct path *path, struct kstat *stat,
u32 request_mask, unsigned int query_flags)
{
struct inode *inode = d_inode(path->dentry);
struct net *net;
net = get_proc_task_net(inode);
generic_fillattr(inode, stat);
if (net != NULL) {
stat->nlink = net->proc_net->nlink;
put_net(net);
}
return 0;
}
const struct inode_operations proc_net_inode_operations = {
.lookup = proc_tgid_net_lookup,
.getattr = proc_tgid_net_getattr,
};
static int proc_tgid_net_readdir(struct file *file, struct dir_context *ctx)
{
int ret;
struct net *net;
ret = -EINVAL;
net = get_proc_task_net(file_inode(file));
if (net != NULL) {
ret = proc_readdir_de(file, ctx, net->proc_net);
put_net(net);
}
return ret;
}
const struct file_operations proc_net_operations = {
.llseek = generic_file_llseek,
.read = generic_read_dir,
.iterate_shared = proc_tgid_net_readdir,
};
static __net_init int proc_net_ns_init(struct net *net)
{
struct proc_dir_entry *netd, *net_statd;
kuid_t uid;
kgid_t gid;
int err;
err = -ENOMEM;
netd = kmem_cache_zalloc(proc_dir_entry_cache, GFP_KERNEL);
if (!netd)
goto out;
netd->subdir = RB_ROOT;
netd->data = net;
netd->nlink = 2;
netd->namelen = 3;
netd->parent = &proc_root;
netd->name = netd->inline_name;
memcpy(netd->name, "net", 4);
uid = make_kuid(net->user_ns, 0);
if (!uid_valid(uid))
uid = netd->uid;
gid = make_kgid(net->user_ns, 0);
if (!gid_valid(gid))
gid = netd->gid;
proc_set_user(netd, uid, gid);
err = -EEXIST;
net_statd = proc_net_mkdir(net, "stat", netd);
if (!net_statd)
goto free_net;
net->proc_net = netd;
net->proc_net_stat = net_statd;
return 0;
free_net:
pde_free(netd);
out:
return err;
}
static __net_exit void proc_net_ns_exit(struct net *net)
{
remove_proc_entry("stat", net->proc_net);
pde_free(net->proc_net);
}
static struct pernet_operations __net_initdata proc_net_ns_ops = {
.init = proc_net_ns_init,
.exit = proc_net_ns_exit,
};
int __init proc_net_init(void)
{
proc_symlink("net", NULL, "self/net");
return register_pernet_subsys(&proc_net_ns_ops);
}