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![Alexey Dobriyan](/assets/img/avatar_default.png)
There are four BKL users in proc: de_put(), proc_lookup_de(), proc_readdir_de(), proc_root_readdir(), 1) de_put() ----------- de_put() is classic atomic_dec_and_test() refcount wrapper -- no BKL needed. BKL doesn't matter to possible refcount leak as well. 2) proc_lookup_de() ------------------- Walking PDE list is protected by proc_subdir_lock(), proc_get_inode() is potentially blocking, all callers of proc_lookup_de() eventually end up from ->lookup hooks which is protected by directory's ->i_mutex -- BKL doesn't protect anything. 3) proc_readdir_de() -------------------- "." and ".." part doesn't need BKL, walking PDE list is under proc_subdir_lock, calling filldir callback is potentially blocking because it writes to luserspace. All proc_readdir_de() callers eventually come from ->readdir hook which is under directory's ->i_mutex -- BKL doesn't protect anything. 4) proc_root_readdir_de() ------------------------- proc_root_readdir_de is ->readdir hook, see (3). Since readdir hooks doesn't use BKL anymore, switch to generic_file_llseek, since it also takes directory's i_mutex. Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
240 lines
4.6 KiB
C
240 lines
4.6 KiB
C
/*
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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 <asm/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/init.h>
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#include <linux/sched.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 <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 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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int seq_open_net(struct inode *ino, struct file *f,
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const struct seq_operations *ops, int size)
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{
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struct net *net;
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struct seq_net_private *p;
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BUG_ON(size < sizeof(*p));
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net = get_proc_net(ino);
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if (net == NULL)
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return -ENXIO;
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p = __seq_open_private(f, ops, size);
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if (p == NULL) {
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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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EXPORT_SYMBOL_GPL(seq_open_net);
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int single_open_net(struct inode *inode, struct file *file,
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int (*show)(struct seq_file *, void *))
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{
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int err;
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struct net *net;
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err = -ENXIO;
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net = get_proc_net(inode);
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if (net == NULL)
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goto err_net;
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err = single_open(file, show, net);
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if (err < 0)
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goto err_open;
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return 0;
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err_open:
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put_net(net);
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err_net:
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return err;
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}
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EXPORT_SYMBOL_GPL(single_open_net);
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int seq_release_net(struct inode *ino, struct file *f)
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{
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struct seq_file *seq;
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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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EXPORT_SYMBOL_GPL(seq_release_net);
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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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EXPORT_SYMBOL_GPL(single_release_net);
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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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ns = task_nsproxy(task);
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if (ns != NULL)
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net = get_net(ns->net_ns);
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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, struct nameidata *nd)
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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(net->proc_net, dir, dentry);
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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 vfsmount *mnt, struct dentry *dentry,
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struct kstat *stat)
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{
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struct inode *inode = dentry->d_inode;
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struct net *net;
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net = get_proc_task_net(inode);
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generic_fillattr(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 *filp, void *dirent,
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filldir_t filldir)
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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(filp->f_path.dentry->d_inode);
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if (net != NULL) {
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ret = proc_readdir_de(net->proc_net, filp, dirent, filldir);
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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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.readdir = proc_tgid_net_readdir,
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};
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struct proc_dir_entry *proc_net_fops_create(struct net *net,
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const char *name, mode_t mode, const struct file_operations *fops)
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{
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return proc_create(name, mode, net->proc_net, fops);
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}
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EXPORT_SYMBOL_GPL(proc_net_fops_create);
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void proc_net_remove(struct net *net, const char *name)
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{
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remove_proc_entry(name, net->proc_net);
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}
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EXPORT_SYMBOL_GPL(proc_net_remove);
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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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int err;
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err = -ENOMEM;
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netd = kzalloc(sizeof(*netd), GFP_KERNEL);
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if (!netd)
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goto out;
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netd->data = net;
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netd->nlink = 2;
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netd->name = "net";
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netd->namelen = 3;
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netd->parent = &proc_root;
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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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kfree(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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kfree(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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