[NET]: Make /proc/net a symlink on /proc/self/net (v3)
Current /proc/net is done with so called "shadows", but current implementation is broken and has little chances to get fixed. The problem is that dentries subtree of /proc/net directory has fancy revalidation rules to make processes living in different net namespaces see different entries in /proc/net subtree, but currently, tasks see in the /proc/net subdir the contents of any other namespace, depending on who opened the file first. The proposed fix is to turn /proc/net into a symlink, which points to /proc/self/net, which in turn shows what previously was in /proc/net - the network-related info, from the net namespace the appropriate task lives in. # ls -l /proc/net lrwxrwxrwx 1 root root 8 Mar 5 15:17 /proc/net -> self/net In other words - this behaves like /proc/mounts, but unlike "mounts", "net" is not a file, but a directory. Changes from v2: * Fixed discrepancy of /proc/net nlink count and selinux labeling screwup pointed out by Stephen. To get the correct nlink count the ->getattr callback for /proc/net is overridden to read one from the net->proc_net entry. To make selinux still work the net->proc_net entry is initialized properly, i.e. with the "net" name and the proc_net parent. Selinux fixes are Acked-by: Stephen Smalley <sds@tycho.nsa.gov> Changes from v1: * Fixed a task_struct leak in get_proc_task_net, pointed out by Paul. Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Acked-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Pavel Emelyanov
David S. Miller
Родитель
1ff82fe002
Коммит
e9720acd72
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@ -2274,6 +2274,7 @@ static const struct pid_entry tgid_base_stuff[] = {
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DIR("task", S_IRUGO|S_IXUGO, task),
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DIR("fd", S_IRUSR|S_IXUSR, fd),
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DIR("fdinfo", S_IRUSR|S_IXUSR, fdinfo),
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DIR("net", S_IRUGO|S_IXUSR, net),
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REG("environ", S_IRUSR, environ),
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INF("auxv", S_IRUSR, pid_auxv),
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ONE("status", S_IRUGO, pid_status),
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@ -377,15 +377,14 @@ static struct dentry_operations proc_dentry_operations =
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* Don't create negative dentries here, return -ENOENT by hand
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* instead.
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*/
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struct dentry *proc_lookup(struct inode * dir, struct dentry *dentry, struct nameidata *nd)
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struct dentry *proc_lookup_de(struct proc_dir_entry *de, struct inode *dir,
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struct dentry *dentry)
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{
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struct inode *inode = NULL;
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struct proc_dir_entry * de;
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int error = -ENOENT;
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lock_kernel();
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spin_lock(&proc_subdir_lock);
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de = PDE(dir);
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if (de) {
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for (de = de->subdir; de ; de = de->next) {
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if (de->namelen != dentry->d_name.len)
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@ -393,8 +392,6 @@ struct dentry *proc_lookup(struct inode * dir, struct dentry *dentry, struct nam
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if (!memcmp(dentry->d_name.name, de->name, de->namelen)) {
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unsigned int ino;
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if (de->shadow_proc)
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de = de->shadow_proc(current, de);
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ino = de->low_ino;
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de_get(de);
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spin_unlock(&proc_subdir_lock);
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@ -417,6 +414,12 @@ out_unlock:
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return ERR_PTR(error);
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}
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struct dentry *proc_lookup(struct inode *dir, struct dentry *dentry,
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struct nameidata *nd)
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{
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return proc_lookup_de(PDE(dir), dir, dentry);
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}
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/*
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* This returns non-zero if at EOF, so that the /proc
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* root directory can use this and check if it should
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@ -426,10 +429,9 @@ out_unlock:
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* value of the readdir() call, as long as it's non-negative
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* for success..
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*/
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int proc_readdir(struct file * filp,
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void * dirent, filldir_t filldir)
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int proc_readdir_de(struct proc_dir_entry *de, struct file *filp, void *dirent,
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filldir_t filldir)
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{
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struct proc_dir_entry * de;
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unsigned int ino;
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int i;
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struct inode *inode = filp->f_path.dentry->d_inode;
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@ -438,7 +440,6 @@ int proc_readdir(struct file * filp,
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lock_kernel();
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ino = inode->i_ino;
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de = PDE(inode);
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if (!de) {
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ret = -EINVAL;
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goto out;
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@ -499,6 +500,13 @@ out: unlock_kernel();
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return ret;
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}
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int proc_readdir(struct file *filp, void *dirent, filldir_t filldir)
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{
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struct inode *inode = filp->f_path.dentry->d_inode;
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return proc_readdir_de(PDE(inode), filp, dirent, filldir);
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}
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/*
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* These are the generic /proc directory operations. They
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* use the in-memory "struct proc_dir_entry" tree to parse
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@ -64,6 +64,8 @@ extern const struct file_operations proc_numa_maps_operations;
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extern const struct file_operations proc_smaps_operations;
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extern const struct file_operations proc_clear_refs_operations;
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extern const struct file_operations proc_pagemap_operations;
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extern const struct file_operations proc_net_operations;
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extern const struct inode_operations proc_net_inode_operations;
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void free_proc_entry(struct proc_dir_entry *de);
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@ -83,3 +85,8 @@ static inline int proc_fd(struct inode *inode)
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{
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return PROC_I(inode)->fd;
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}
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struct dentry *proc_lookup_de(struct proc_dir_entry *de, struct inode *ino,
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struct dentry *dentry);
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int proc_readdir_de(struct proc_dir_entry *de, struct file *filp, void *dirent,
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filldir_t filldir);
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@ -63,6 +63,82 @@ int seq_release_net(struct inode *ino, struct file *f)
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}
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EXPORT_SYMBOL_GPL(seq_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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.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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@ -83,14 +159,6 @@ struct net *get_proc_net(const struct inode *inode)
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}
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EXPORT_SYMBOL_GPL(get_proc_net);
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static struct proc_dir_entry *shadow_pde;
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static struct proc_dir_entry *proc_net_shadow(struct task_struct *task,
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struct proc_dir_entry *de)
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{
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return task->nsproxy->net_ns->proc_net;
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}
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struct proc_dir_entry *proc_net_mkdir(struct net *net, const char *name,
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struct proc_dir_entry *parent)
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{
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@ -104,45 +172,39 @@ EXPORT_SYMBOL_GPL(proc_net_mkdir);
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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 *root, *netd, *net_statd;
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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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root = kzalloc(sizeof(*root), GFP_KERNEL);
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if (!root)
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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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err = -EEXIST;
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netd = proc_net_mkdir(net, "net", root);
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if (!netd)
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goto free_root;
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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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root->data = net;
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net->proc_net_root = root;
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net->proc_net = netd;
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net->proc_net_stat = net_statd;
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err = 0;
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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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free_net:
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remove_proc_entry("net", root);
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free_root:
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kfree(root);
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goto out;
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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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remove_proc_entry("net", net->proc_net_root);
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kfree(net->proc_net_root);
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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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@ -152,8 +214,7 @@ static struct pernet_operations __net_initdata proc_net_ns_ops = {
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int __init proc_net_init(void)
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{
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shadow_pde = proc_mkdir("net", NULL);
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shadow_pde->shadow_proc = proc_net_shadow;
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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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@ -50,8 +50,6 @@ typedef int (read_proc_t)(char *page, char **start, off_t off,
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typedef int (write_proc_t)(struct file *file, const char __user *buffer,
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unsigned long count, void *data);
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typedef int (get_info_t)(char *, char **, off_t, int);
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typedef struct proc_dir_entry *(shadow_proc_t)(struct task_struct *task,
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struct proc_dir_entry *pde);
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struct proc_dir_entry {
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unsigned int low_ino;
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@ -82,7 +80,6 @@ struct proc_dir_entry {
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int pde_users; /* number of callers into module in progress */
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spinlock_t pde_unload_lock; /* proc_fops checks and pde_users bumps */
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struct completion *pde_unload_completion;
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shadow_proc_t *shadow_proc;
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};
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struct kcore_list {
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@ -31,7 +31,6 @@ struct net {
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struct proc_dir_entry *proc_net;
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struct proc_dir_entry *proc_net_stat;
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struct proc_dir_entry *proc_net_root;
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struct list_head sysctl_table_headers;
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