Re: when and where shall I encrypt dentry?

[linux-os]

The correct place to encrypt or decrypt ANYTHING is
just before access to the "outside" world, i.e., in the
case of a file-system, the reads and writes to the
storage device (disk drive). You are in a world of
hurt if you intend to encrypt 'data' and directories
separately.
If you need to use an existing file-system and then
encrypt it, you use the same technique but your
"storage device" is a "container file" that you mount
using the loop device. This allows you to have an
encrypted file-system below some mount-point and
a normal file-system above.
FYI, there are existing tools/code that allow one to
mount an encrypted file-system. Perhaps your masters
project just got easier?
On Wed, 2 Feb 2005, Vineet Joglekar wrote:
Hi all,
I am trying to add some cryptographic functionality to ext2 file system for my 
masters project. I am working with kernel 2.4.21
Along with regular files, I intend to encrypt directory contents too. For 
reading I guess the function ext2_get_page in fs/ext2/dir.c is used. Hence I 
can put my decryption routine in that function. Is that correct?
I was trying to look for the routine which writes the dentry on disk, but was 
unable to find it. I found out that the function d_instantiate is used to fill 
in inode information for a dentry, but unable to see when it is written on 
disk. I suppose that I have to encrypt the dentry just before writing on to the 
disk, as if i encrypt it before, other functions using it wont be able to 
access until they decrypt. So please help me with this, that when and where 
shall I encrypt the directory contents.
Thanks and regards,
Vineet
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Re: __init()

[linux-os \(Dick Johnson\)]

On Thu, 11 Aug 2005, raja wrote:

> Hi,
> Is there any way to execute my own __init() instead of default
> __init() while running an executable.
> -

Sure you link your object file with your own instead of using
the default

 gcc -c -o myprog.o myprog.c
 as -o start.o start.S

 ld -o myprog myprog.o start.o /lib/libc.so.6
 |   |  |___ runtime lib
 |   |__ Your startup
 |__ Your program

Startup starts with a label _start. You may have to write it
in assembly. It calls main() and must never return. Instead
it calls exit() with whatever main() returned, to quit.

__init() is some M$ thing. Linux executables start with
_start().

Cheers,
Dick Johnson
Penguin : Linux version 2.6.12 on an i686 machine (5537.79 BogoMips).
Warning : 98.36% of all statistics are fiction.
.
I apologize for the following. I tried to kill it with the above dot :


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