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authorPavel Emelyanov <xemul@openvz.org>2008-03-07 22:08:40 +0300
committerDavid S. Miller <davem@davemloft.net>2008-03-07 22:08:40 +0300
commite9720acd728a46cb40daa52c99a979f7c4ff195c (patch)
tree01380f601384cf93f30dedb64afe80359fecb807 /fs/proc/proc_net.c
parent1ff82fe0024e8070c38346b8abc1ff09612dea4c (diff)
downloadlinux-e9720acd728a46cb40daa52c99a979f7c4ff195c.tar.xz
[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>
Diffstat (limited to 'fs/proc/proc_net.c')
-rw-r--r--fs/proc/proc_net.c117
1 files changed, 89 insertions, 28 deletions
diff --git a/fs/proc/proc_net.c b/fs/proc/proc_net.c
index 14e9b5aaf863..4caa5f774fb7 100644
--- a/fs/proc/proc_net.c
+++ b/fs/proc/proc_net.c
@@ -63,6 +63,82 @@ int seq_release_net(struct inode *ino, struct file *f)
}
EXPORT_SYMBOL_GPL(seq_release_net);
+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) {
+ ns = task_nsproxy(task);
+ if (ns != NULL)
+ net = get_net(ns->net_ns);
+ }
+ rcu_read_unlock();
+
+ return net;
+}
+
+static struct dentry *proc_tgid_net_lookup(struct inode *dir,
+ struct dentry *dentry, struct nameidata *nd)
+{
+ struct dentry *de;
+ struct net *net;
+
+ de = ERR_PTR(-ENOENT);
+ net = get_proc_task_net(dir);
+ if (net != NULL) {
+ de = proc_lookup_de(net->proc_net, dir, dentry);
+ put_net(net);
+ }
+ return de;
+}
+
+static int proc_tgid_net_getattr(struct vfsmount *mnt, struct dentry *dentry,
+ struct kstat *stat)
+{
+ struct inode *inode = dentry->d_inode;
+ 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 *filp, void *dirent,
+ filldir_t filldir)
+{
+ int ret;
+ struct net *net;
+
+ ret = -EINVAL;
+ net = get_proc_task_net(filp->f_path.dentry->d_inode);
+ if (net != NULL) {
+ ret = proc_readdir_de(net->proc_net, filp, dirent, filldir);
+ put_net(net);
+ }
+ return ret;
+}
+
+const struct file_operations proc_net_operations = {
+ .read = generic_read_dir,
+ .readdir = proc_tgid_net_readdir,
+};
+
struct proc_dir_entry *proc_net_fops_create(struct net *net,
const char *name, mode_t mode, const struct file_operations *fops)
@@ -83,14 +159,6 @@ struct net *get_proc_net(const struct inode *inode)
}
EXPORT_SYMBOL_GPL(get_proc_net);
-static struct proc_dir_entry *shadow_pde;
-
-static struct proc_dir_entry *proc_net_shadow(struct task_struct *task,
- struct proc_dir_entry *de)
-{
- return task->nsproxy->net_ns->proc_net;
-}
-
struct proc_dir_entry *proc_net_mkdir(struct net *net, const char *name,
struct proc_dir_entry *parent)
{
@@ -104,45 +172,39 @@ EXPORT_SYMBOL_GPL(proc_net_mkdir);
static __net_init int proc_net_ns_init(struct net *net)
{
- struct proc_dir_entry *root, *netd, *net_statd;
+ struct proc_dir_entry *netd, *net_statd;
int err;
err = -ENOMEM;
- root = kzalloc(sizeof(*root), GFP_KERNEL);
- if (!root)
+ netd = kzalloc(sizeof(*netd), GFP_KERNEL);
+ if (!netd)
goto out;
- err = -EEXIST;
- netd = proc_net_mkdir(net, "net", root);
- if (!netd)
- goto free_root;
+ netd->data = net;
+ netd->nlink = 2;
+ netd->name = "net";
+ netd->namelen = 3;
+ netd->parent = &proc_root;
err = -EEXIST;
net_statd = proc_net_mkdir(net, "stat", netd);
if (!net_statd)
goto free_net;
- root->data = net;
-
- net->proc_net_root = root;
net->proc_net = netd;
net->proc_net_stat = net_statd;
- err = 0;
+ return 0;
+free_net:
+ kfree(netd);
out:
return err;
-free_net:
- remove_proc_entry("net", root);
-free_root:
- kfree(root);
- goto out;
}
static __net_exit void proc_net_ns_exit(struct net *net)
{
remove_proc_entry("stat", net->proc_net);
- remove_proc_entry("net", net->proc_net_root);
- kfree(net->proc_net_root);
+ kfree(net->proc_net);
}
static struct pernet_operations __net_initdata proc_net_ns_ops = {
@@ -152,8 +214,7 @@ static struct pernet_operations __net_initdata proc_net_ns_ops = {
int __init proc_net_init(void)
{
- shadow_pde = proc_mkdir("net", NULL);
- shadow_pde->shadow_proc = proc_net_shadow;
+ proc_symlink("net", NULL, "self/net");
return register_pernet_subsys(&proc_net_ns_ops);
}