1 files changed, 148 insertions, 21 deletions

diff --git a/fs/proc/namespaces.c b/fs/proc/namespaces.c
index 030250c27d70..7a6d8d69cdb8 100644
--- a/fs/proc/namespaces.c
+++ b/fs/proc/namespaces.c
@@ -38,6 +38,151 @@ static const struct file_operations ns_file_operations = {
 	.llseek		= no_llseek,
 };
 
+static const struct inode_operations ns_inode_operations = {
+	.setattr	= proc_setattr,
+};
+
+static int ns_delete_dentry(const struct dentry *dentry)
+{
+	/* Don't cache namespace inodes when not in use */
+	return 1;
+}
+
+static char *ns_dname(struct dentry *dentry, char *buffer, int buflen)
+{
+	struct inode *inode = dentry->d_inode;
+	const struct proc_ns_operations *ns_ops = PROC_I(inode)->ns_ops;
+
+	return dynamic_dname(dentry, buffer, buflen, "%s:[%lu]",
+		ns_ops->name, inode->i_ino);
+}
+
+const struct dentry_operations ns_dentry_operations =
+{
+	.d_delete	= ns_delete_dentry,
+	.d_dname	= ns_dname,
+};
+
+static struct dentry *proc_ns_get_dentry(struct super_block *sb,
+	struct task_struct *task, const struct proc_ns_operations *ns_ops)
+{
+	struct dentry *dentry, *result;
+	struct inode *inode;
+	struct proc_inode *ei;
+	struct qstr qname = { .name = "", };
+	void *ns;
+
+	ns = ns_ops->get(task);
+	if (!ns)
+		return ERR_PTR(-ENOENT);
+
+	dentry = d_alloc_pseudo(sb, &qname);
+	if (!dentry) {
+		ns_ops->put(ns);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	inode = new_inode(sb);
+	if (!inode) {
+		dput(dentry);
+		ns_ops->put(ns);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	ei = PROC_I(inode);
+	inode->i_ino = get_next_ino();
+	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
+	inode->i_op = &ns_inode_operations;
+	inode->i_mode = S_IFREG | S_IRUGO;
+	inode->i_fop = &ns_file_operations;
+	ei->ns_ops = ns_ops;
+	ei->ns = ns;
+
+	d_set_d_op(dentry, &ns_dentry_operations);
+	result = d_instantiate_unique(dentry, inode);
+	if (result) {
+		dput(dentry);
+		dentry = result;
+	}
+
+	return dentry;
+}
+
+static void *proc_ns_follow_link(struct dentry *dentry, struct nameidata *nd)
+{
+	struct inode *inode = dentry->d_inode;
+	struct super_block *sb = inode->i_sb;
+	struct proc_inode *ei = PROC_I(inode);
+	struct task_struct *task;
+	struct dentry *ns_dentry;
+	void *error = ERR_PTR(-EACCES);
+
+	task = get_proc_task(inode);
+	if (!task)
+		goto out;
+
+	if (!ptrace_may_access(task, PTRACE_MODE_READ))
+		goto out_put_task;
+
+	ns_dentry = proc_ns_get_dentry(sb, task, ei->ns_ops);
+	if (IS_ERR(ns_dentry)) {
+		error = ERR_CAST(ns_dentry);
+		goto out_put_task;
+	}
+
+	dput(nd->path.dentry);
+	nd->path.dentry = ns_dentry;
+	error = NULL;
+
+out_put_task:
+	put_task_struct(task);
+out:
+	return error;
+}
+
+static int proc_ns_readlink(struct dentry *dentry, char __user *buffer, int buflen)
+{
+	struct inode *inode = dentry->d_inode;
+	struct proc_inode *ei = PROC_I(inode);
+	const struct proc_ns_operations *ns_ops = ei->ns_ops;
+	struct task_struct *task;
+	void *ns;
+	char name[50];
+	int len = -EACCES;
+
+	task = get_proc_task(inode);
+	if (!task)
+		goto out;
+
+	if (!ptrace_may_access(task, PTRACE_MODE_READ))
+		goto out_put_task;
+
+	len = -ENOENT;
+	ns = ns_ops->get(task);
+	if (!ns)
+		goto out_put_task;
+
+	snprintf(name, sizeof(name), "%s", ns_ops->name);
+	len = strlen(name);
+
+	if (len > buflen)
+		len = buflen;
+	if (copy_to_user(buffer, ns_ops->name, len))
+		len = -EFAULT;
+
+	ns_ops->put(ns);
+out_put_task:
+	put_task_struct(task);
+out:
+	return len;
+}
+
+static const struct inode_operations proc_ns_link_inode_operations = {
+	.readlink	= proc_ns_readlink,
+	.follow_link	= proc_ns_follow_link,
+	.setattr	= proc_setattr,
+};
+
 static struct dentry *proc_ns_instantiate(struct inode *dir,
 	struct dentry *dentry, struct task_struct *task, const void *ptr)
 {
@@ -45,21 +190,15 @@ static struct dentry *proc_ns_instantiate(struct inode *dir,
 	struct inode *inode;
 	struct proc_inode *ei;
 	struct dentry *error = ERR_PTR(-ENOENT);
-	void *ns;
 
 	inode = proc_pid_make_inode(dir->i_sb, task);
 	if (!inode)
 		goto out;
 
-	ns = ns_ops->get(task);
-	if (!ns)
-		goto out_iput;
-
 	ei = PROC_I(inode);
-	inode->i_mode = S_IFREG|S_IRUSR;
-	inode->i_fop  = &ns_file_operations;
-	ei->ns_ops    = ns_ops;
-	ei->ns	      = ns;
+	inode->i_mode = S_IFLNK|S_IRWXUGO;
+	inode->i_op = &proc_ns_link_inode_operations;
+	ei->ns_ops = ns_ops;
 
 	d_set_d_op(dentry, &pid_dentry_operations);
 	d_add(dentry, inode);
@@ -68,9 +207,6 @@ static struct dentry *proc_ns_instantiate(struct inode *dir,
 		error = NULL;
 out:
 	return error;
-out_iput:
-	iput(inode);
-	goto out;
 }
 
 static int proc_ns_fill_cache(struct file *filp, void *dirent,
@@ -97,10 +233,6 @@ static int proc_ns_dir_readdir(struct file *filp, void *dirent,
 	if (!task)
 		goto out_no_task;
 
-	ret = -EPERM;
-	if (!ptrace_may_access(task, PTRACE_MODE_READ))
-		goto out;
-
 	ret = 0;
 	i = filp->f_pos;
 	switch (i) {
@@ -160,10 +292,6 @@ static struct dentry *proc_ns_dir_lookup(struct inode *dir,
 	if (!task)
 		goto out_no_task;
 
-	error = ERR_PTR(-EPERM);
-	if (!ptrace_may_access(task, PTRACE_MODE_READ))
-		goto out;
-
 	last = &ns_entries[ARRAY_SIZE(ns_entries)];
 	for (entry = ns_entries; entry < last; entry++) {
 		if (strlen((*entry)->name) != len)
@@ -171,7 +299,6 @@ static struct dentry *proc_ns_dir_lookup(struct inode *dir,
 		if (!memcmp(dentry->d_name.name, (*entry)->name, len))
 			break;
 	}
-	error = ERR_PTR(-ENOENT);
 	if (entry == last)
 		goto out;