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Date: Sat, 10 Sep 2011 17:21:01 +0400
From: Vasiliy Kulikov <segoon@...nwall.com>
To: kernel-hardening@...ts.openwall.com
Cc: Andrew Morton <akpm@...ux-foundation.org>, Tejun Heo <tj@...nel.org>,
"Kirill A. Shutemov" <kirill@...temov.name>,
containers@...ts.osdl.org, linux-kernel@...r.kernel.org,
linux-fsdevel@...r.kernel.org, Nathan Lynch <ntl@...ox.com>,
Oren Laadan <orenl@...columbia.edu>,
Daniel Lezcano <dlezcano@...ibm.com>,
Glauber Costa <glommer@...allels.com>,
James Bottomley <jbottomley@...allels.com>,
Alexey Dobriyan <adobriyan@...il.com>,
Al Viro <viro@...IV.linux.org.uk>,
Pavel Emelyanov <xemul@...allels.com>
Subject: Re: Re: [patch 2/2] fs, proc: Introduce the
/proc/<pid>/map_files/ directory v6
Hi Cyrill,
On Thu, Sep 08, 2011 at 10:04 +0400, Cyrill Gorcunov wrote:
> +static int map_files_d_revalidate(struct dentry *dentry, struct nameidata *nd)
> +{
> + unsigned long vm_start, vm_end;
> + bool exact_vma_exists = false;
> + struct task_struct *task;
> + const struct cred *cred;
> + struct mm_struct *mm;
> + struct inode *inode;
> +
> + if (nd && nd->flags & LOOKUP_RCU)
> + return -ECHILD;
> +
> + inode = dentry->d_inode;
> + task = get_proc_task(inode);
> + if (!task)
> + goto out;
> +
> + if (!ptrace_may_access(task, PTRACE_MODE_READ))
put_task_struct(task) belongs here.
> + goto out;
> +
> + mm = get_task_mm(task);
> + put_task_struct(task);
> + if (!mm)
> + goto out;
> +
> + if (!dname_to_vma_addr(dentry, &vm_start, &vm_end)) {
> + down_read(&mm->mmap_sem);
> + exact_vma_exists = !!find_exact_vma(mm, vm_start, vm_end);
> + up_read(&mm->mmap_sem);
> + }
> +
> + mmput(mm);
> +
> + if (exact_vma_exists) {
> + if (task_dumpable(task)) {
> + rcu_read_lock();
> + cred = __task_cred(task);
> + inode->i_uid = cred->euid;
> + inode->i_gid = cred->egid;
> + rcu_read_unlock();
> + } else {
> + inode->i_uid = 0;
> + inode->i_gid = 0;
> + }
> + security_task_to_inode(task, inode);
> + return 1;
> + }
> +out:
> + d_drop(dentry);
> + return 0;
> +}
Thanks,
--
Vasiliy Kulikov
http://www.openwall.com - bringing security into open computing environments
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