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Message-ID: <47D12EF8.8010801@openvz.org>
Date: Fri, 07 Mar 2008 15:03:04 +0300
From: Pavel Emelyanov <xemul@...nvz.org>
To: Stephen Smalley <sds@...ho.nsa.gov>
CC: Andrew Morton <akpm@...ux-foundation.org>,
David Miller <davem@...emloft.net>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Linux Netdev List <netdev@...r.kernel.org>,
"Eric W. Biederman" <ebiederm@...ssion.com>,
"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
James Morris <jmorris@...ei.org>,
Eric Paris <eparis@...isplace.org>
Subject: Re: [PATCH] Make /proc/net a symlink on /proc/self/net (v2)
[snip]
>>> Does this break SELinux labeling of /proc/net inodes and thus its access
>>> controls on them?
>> It should not, since the proc_dir_etries are still organized in
>> a required hierarchy.
>
> Unfortunately, it does break selinux labeling of /proc/net inodes.
> Easily seen by running ls -ZR /proc/net before and after the patch is
> applied and comparing the results.
>
> Also, as a separate issue, a "find /proc/self/net ..." will show that
> the hard link count is wrong for it.
Oops... I've checked this thing explicitly before sending, but it looks
like I used too old find version. I.e. 4.1.20 worked OK, but 4.2.23
reported the nlink discrepancy.
Anyway, this is fixed now (see below). I override the getattr method for
/proc/net directory and update one from the net->proc_net entry, which
is calculated correctly.
> Currently the inodes get labeled by selinux_proc_get_sid() by walking up
> the proc_dir_entry tree to generate a name and prefix matching that name
> in policy. Before the patch, we'd get names like "//net/tcp", i.e.
> relative to the root of proc (the extra leading slash is due to the
> earlier proc net rewrite which also broke selinux until we adjusted it
> to ignore it). After the patch, we just get "//tcp", which is ambiguous
> since we would also get that for a /proc/tcp inode if one existed.
OK, got it. Is it good if we used to get the //net/tcp, but will /net/tcp
(without the double slash)? The patch below does exactly this. It initializes
the name for the net->proc_net entry and makes its parent be proc_root.
Can you Ack this patch, so that I can merge it with the original one and
re-post the combined v3?
> Not trying to obstruct your proc net improvements, but just want to make
> sure that selinux doesn't get broken in the process.
diff --git a/fs/proc/proc_net.c b/fs/proc/proc_net.c
index 18d413c..4caa5f7 100644
--- a/fs/proc/proc_net.c
+++ b/fs/proc/proc_net.c
@@ -96,8 +96,27 @@ static struct dentry *proc_tgid_net_lookup(struct inode *dir,
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,
@@ -162,6 +181,10 @@ static __net_init int proc_net_ns_init(struct net *net)
goto out;
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);
--
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