From 2b1e300a9dfc3196ccddf6f1d74b91b7af55e416 Mon Sep 17 00:00:00 2001
From: "Eric W. Biederman" <ebiederm@xmission.com>
Date: Sun, 2 Dec 2007 00:33:17 +1100
Subject: [NETNS]: Fix /proc/net breakage
Well I clearly goofed when I added the initial network namespace support
for /proc/net. Currently things work but there are odd details visible to
user space, even when we have a single network namespace.
Since we do not cache proc_dir_entry dentries at the moment we can just
modify ->lookup to return a different directory inode depending on the
network namespace of the process looking at /proc/net, replacing the
current technique of using a magic and fragile follow_link method.
To accomplish that this patch:
- introduces a shadow_proc method to allow different dentries to
be returned from proc_lookup.
- Removes the old /proc/net follow_link magic
- Fixes a weakness in our not caching of proc generic dentries.
As shadow_proc uses a task struct to decided which dentry to return we can
go back later and fix the proc generic caching without modifying any code
that uses the shadow_proc method.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
---
fs/proc/generic.c | 12 +++++++-
fs/proc/proc_net.c | 86 ++++--------------------------------------------------
2 files changed, 16 insertions(+), 82 deletions(-)
(limited to 'fs/proc')
diff --git a/fs/proc/generic.c b/fs/proc/generic.c
index a9806bc21e..c2b752341f 100644
--- a/fs/proc/generic.c
+++ b/fs/proc/generic.c
@@ -374,9 +374,16 @@ static int proc_delete_dentry(struct dentry * dentry)
return 1;
}
+static int proc_revalidate_dentry(struct dentry *dentry, struct nameidata *nd)
+{
+ d_drop(dentry);
+ return 0;
+}
+
static struct dentry_operations proc_dentry_operations =
{
.d_delete = proc_delete_dentry,
+ .d_revalidate = proc_revalidate_dentry,
};
/*
@@ -397,8 +404,11 @@ struct dentry *proc_lookup(struct inode * dir, struct dentry *dentry, struct nam
if (de->namelen != dentry->d_name.len)
continue;
if (!memcmp(dentry->d_name.name, de->name, de->namelen)) {
- unsigned int ino = de->low_ino;
+ unsigned int ino;
+ if (de->shadow_proc)
+ de = de->shadow_proc(current, de);
+ ino = de->low_ino;
de_get(de);
spin_unlock(&proc_subdir_lock);
error = -EINVAL;
diff --git a/fs/proc/proc_net.c b/fs/proc/proc_net.c
index 131f9c68be..0afe21ee06 100644
--- a/fs/proc/proc_net.c
+++ b/fs/proc/proc_net.c
@@ -50,89 +50,14 @@ struct net *get_proc_net(const struct inode *inode)
}
EXPORT_SYMBOL_GPL(get_proc_net);
-static struct proc_dir_entry *proc_net_shadow;
+static struct proc_dir_entry *shadow_pde;
-static struct dentry *proc_net_shadow_dentry(struct dentry *parent,
+static struct proc_dir_entry *proc_net_shadow(struct task_struct *task,
struct proc_dir_entry *de)
{
- struct dentry *shadow = NULL;
- struct inode *inode;
- if (!de)
- goto out;
- de_get(de);
- inode = proc_get_inode(parent->d_inode->i_sb, de->low_ino, de);
- if (!inode)
- goto out_de_put;
- shadow = d_alloc_name(parent, de->name);
- if (!shadow)
- goto out_iput;
- shadow->d_op = parent->d_op; /* proc_dentry_operations */
- d_instantiate(shadow, inode);
-out:
- return shadow;
-out_iput:
- iput(inode);
-out_de_put:
- de_put(de);
- goto out;
-}
-
-static void *proc_net_follow_link(struct dentry *parent, struct nameidata *nd)
-{
- struct net *net = current->nsproxy->net_ns;
- struct dentry *shadow;
- shadow = proc_net_shadow_dentry(parent, net->proc_net);
- if (!shadow)
- return ERR_PTR(-ENOENT);
-
- dput(nd->dentry);
- /* My dentry count is 1 and that should be enough as the
- * shadow dentry is thrown away immediately.
- */
- nd->dentry = shadow;
- return NULL;
+ return task->nsproxy->net_ns->proc_net;
}
-static struct dentry *proc_net_lookup(struct inode *dir, struct dentry *dentry,
- struct nameidata *nd)
-{
- struct net *net = current->nsproxy->net_ns;
- struct dentry *shadow;
-
- shadow = proc_net_shadow_dentry(nd->dentry, net->proc_net);
- if (!shadow)
- return ERR_PTR(-ENOENT);
-
- dput(nd->dentry);
- nd->dentry = shadow;
-
- return shadow->d_inode->i_op->lookup(shadow->d_inode, dentry, nd);
-}
-
-static int proc_net_setattr(struct dentry *dentry, struct iattr *iattr)
-{
- struct net *net = current->nsproxy->net_ns;
- struct dentry *shadow;
- int ret;
-
- shadow = proc_net_shadow_dentry(dentry->d_parent, net->proc_net);
- if (!shadow)
- return -ENOENT;
- ret = shadow->d_inode->i_op->setattr(shadow, iattr);
- dput(shadow);
- return ret;
-}
-
-static const struct file_operations proc_net_dir_operations = {
- .read = generic_read_dir,
-};
-
-static struct inode_operations proc_net_dir_inode_operations = {
- .follow_link = proc_net_follow_link,
- .lookup = proc_net_lookup,
- .setattr = proc_net_setattr,
-};
-
static __net_init int proc_net_ns_init(struct net *net)
{
struct proc_dir_entry *root, *netd, *net_statd;
@@ -185,9 +110,8 @@ static struct pernet_operations __net_initdata proc_net_ns_ops = {
int __init proc_net_init(void)
{
- proc_net_shadow = proc_mkdir("net", NULL);
- proc_net_shadow->proc_iops = &proc_net_dir_inode_operations;
- proc_net_shadow->proc_fops = &proc_net_dir_operations;
+ shadow_pde = proc_mkdir("net", NULL);
+ shadow_pde->shadow_proc = proc_net_shadow;
return register_pernet_subsys(&proc_net_ns_ops);
}
--
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