linux-kernel - Re: [RFC] fs, proc: Introduce the /proc/<pid>/map

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Date:	Wed, 24 Aug 2011 15:18:06 +0400
From:	Vasiliy Kulikov <segoon@...nwall.com>
To:	Cyrill Gorcunov <gorcunov@...il.com>
Cc:	Nathan Lynch <ntl@...ox.com>, Oren Laadan <orenl@...columbia.edu>,
	Daniel Lezcano <dlezcano@...ibm.com>,
	Tejun Heo <tj@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Pavel Emelyanov <xemul@...allels.com>,
	linux-kernel@...r.kernel.org,
	James Bottomley <jbottomley@...allels.com>,
	LINUXFS-ML <linux-fsdevel@...r.kernel.org>,
	containers@...ts.osdl.org
Subject: Re: [RFC] fs, proc: Introduce the /proc/<pid>/map_files/ directory
 v2

Hi Cyrill,

On Wed, Aug 24, 2011 at 12:53 +0400, Cyrill Gorcunov wrote:
> +static struct dentry *proc_map_files_lookup(struct inode *dir,
> +		struct dentry *dentry, struct nameidata *nd)
> +{
> +	struct task_struct *task;
> +	unsigned long vm_start;
> +	struct vm_area_struct *vma;
> +	struct mm_struct *mm;
> +	struct dentry *result;
> +	char *endp;
> +
> +	result = ERR_PTR(-ENOENT);
> +
> +	task = get_proc_task(dir);
> +	if (!task)
> +		goto out_no_task;
> +
> +	vm_start = simple_strtoul(dentry->d_name.name, &endp, 16);
> +	if (*endp != '\0')
> +		goto out_no_mm;
> +
> +	mm = get_task_mm(task);
> +	if (!mm)
> +		goto out_no_mm;
> +
> +	down_read(&mm->mmap_sem);
> +	vma = find_vma(mm, vm_start);
> +	if (!vma || vma->vm_start != vm_start)
> +		goto out_no_vma;
> +	result = proc_map_files_instantiate(dir, dentry, task, vma);
> +
> +out_no_vma:
> +	up_read(&mm->mmap_sem);
> +	mmput(mm);
> +out_no_mm:
> +	put_task_struct(task);
> +out_no_task:
> +	return result;
> +}

You have no ptrace_may_access() check in ->lookup(), only in ->readdir().

> +static const struct inode_operations proc_map_files_inode_operations = {
> +	.lookup		= proc_map_files_lookup,
> +	.setattr	= proc_setattr,
> +};
> +
> +static int proc_map_files_readdir(struct file *filp, void *dirent, filldir_t filldir)
> +{
...
> +	ret = -EPERM;
> +	if (!ptrace_may_access(task, PTRACE_MODE_READ))
> +		goto out;
...
> +	}

Thanks,

-- 
Vasiliy
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