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SubjectRe: [RFC] fs, proc: Introduce the /proc/<pid>/map_files/ directory v2
Hello,

On Thu, Aug 25, 2011 at 12:29:44PM +0400, Cyrill Gorcunov wrote:
> | lr-x------ 1 cyrill cyrill 64 Aug 9 15:25 0x3d73a00000 -> /lib64/ld-2.5.so
> | lr-x------ 1 cyrill cyrill 64 Aug 9 15:25 0x3d73c1b000 -> /lib64/ld-2.5.so
> | lr-x------ 1 cyrill cyrill 64 Aug 9 15:25 0x3d73c1c000 -> /lib64/ld-2.5.so
> | lr-x------ 1 cyrill cyrill 64 Aug 9 15:25 0x3d73e00000 -> /lib64/libc-2.5.so
> | lr-x------ 1 cyrill cyrill 64 Aug 9 15:25 0x3d73f4e000 -> /lib64/libc-2.5.so

I would prefer if the filename included both start and end addresses
so that it matches the first column of /proc/PID/maps and ls'ing the
directory is more useful. What do other people think?

> +static int map_files_d_revalidate(struct dentry *dentry, struct nameidata *nd)
> +{
> + struct task_struct *task;
> + struct vm_area_struct *vma;
> + 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;
> +
> + mm = get_task_mm(task);
> + put_task_struct(task);
> + if (!mm)
> + goto out;
> +
> + down_read(&mm->mmap_sem);
> + vma = find_exact_vma(mm, PROC_I(inode)->vm_start);
> + up_read(&mm->mmap_sem);
> + mmput(mm);
> +
> + if (vma)
> + return 1;

Hmm... don't we need the same credential update as
tid_fd_revalidate()? If the task seteuid's, we want the permissions
to change accordingly, right?

Thanks.

--
tejun


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