On Mon, Oct 15, 2012 at 7:07 PM, <sf...@users.sourceforge.net> wrote:
>
> Hmm...
> Just to make sure, you can success chdir("/mnt[012]/home/username"), right?
> Will you show me the output of this command?
>
> $ ls -ld / /mnt[012] /mnt[012]/home /mnt[012]/home/username /home
> /home/username
>
> chdir(2) essentially calls two kernel internal functions,
> user_path_dir() and inode_permission(). Can you distinguish which one
> returns EACCES by ftrace or something? If not, will you try this patch
> which is just for debug print?
>
> diff --git a/fs/open.c b/fs/open.c
> index 7e4c856..26e682e 100644
> --- a/fs/open.c
> +++ b/fs/open.c
> @@ -382,12 +382,18 @@ SYSCALL_DEFINE1(chdir, const char __user *, filename)
> int error;
>
> error = user_path_dir(filename, &path);
> - if (error)
> + if (error) {
> + pr_err("%s:%d: %d\n", __func__, __LINE__, error);
> goto out;
> + }
>
> error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
> - if (error)
> + if (error) {
> + pr_err("%s:%d: %.*s, %d\n", __func__, __LINE__,
> + path.dentry->d_name.len, path.dentry->d_name.name,
> + error);
> goto dput_and_out;
> + }
>
> set_fs_pwd(current->fs, &path);
>
>
> J. R. Okajima
Unfortunately it is not easy to check chdir("/mnt[012]/home/username")
since /mnt[012] are no longer available after startup.
But I got the solution:
Change mode of my "changes" directory from 700 to 755.
Strange that it worked in aufs3.2. And ...
1) "changes" is the branch in the middle:
tmpfs(empty,rw):changes(ext2,ro):squashfs(rr)
The only things in "changes" are "etc/fstab" and
"lib/{firmware,modules}".
2) "/home" is mounted over aufs.
Anyway, after applying the patch I get the following debug output:
[ 20.755352] sys_chdir:388: -2
[ 28.630147] sys_chdir:388: -13
[ 28.630162] sys_chdir:396: /, -13
Guan
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