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Thread: Ownership of encrpted USBdrive with ext4

  1. #11
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    Default Re: Ownership of encrpted USBdrive with ext4

    Quote Originally Posted by opensuseinmanila View Post

    Apart from that, using FAT for an encrypted partition on an external device seems to be the easier thing to do. Would you agree?
    I would never agree with using a non-Linux file system type on Linux for anything else then the exchange of data with non-Linux systems. It may be "easier" (I do not know), but not cleverer. At least when one of your arguments behind using Linux is it's increased security vs. Windows.
    Henk van Velden

  2. #12
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    Default Re: Ownership of encrpted USBdrive with ext4

    On 2014-03-13 15:46, opensuseinmanila wrote:

    > Allow me to go back to post #1 and the quote from paragraph 10.1.4 of
    > the documentation for openSUSE 12.3: "For devices with a file system
    > other than FAT, change the ownership explicitly for users other than
    > root to enable these users to read or write files on the device." This
    > is where it all started. Although English is not my native language I
    > would say that the natural interpretation of this clause is that
    > ownership is a property of the -device: -"For devices...change the
    > ownership..." Ownership of what? Of the device. Although technically
    > this is not the correct answer as I know now.


    No.

    Also, I guess that the people that wrote that did not have English as
    their first language ;-)

    It means that on FAT devices you indeed set the permissions for the
    entire device partition. Or to be precise, you fake them.

    (and it also applies to NTFS).

    On non FAT devices, that is, on proper Linux devices, instead you change
    the permissions of directories and permissions in the standard, ages
    old, Unix way (change explicitly). You do it file by file, directory by
    directory, one by one, or massively on a lot of them. But any new file
    can have any other combination of ownership and permissions.


    What you did with dolphin is that you change the permission of the
    "parent" directory (some say the root directory, but that is confusing).
    Once you have permission to write on the parent directory as a normal
    user, you can, as that same user, add new files and directories, which
    will belong to the user that creates them (which may or not be the one
    that owns the parent directory).


    Please, find a book on Unix or Linux and learn how permissions work
    here. You need reading a text that explains it properly, not make
    guesses at how to do things, or even ask us questions. We can not
    explain it all in a post - in that case we'd write the book instead! :-)


    > I am sorry that I caused a lot of confusion here. But part of the
    > confusion is caused by my interpretation of the documentation.


    Documentation written by programmers is often difficult to understand by
    non-programmers.


    > Apart from that, using FAT for an encrypted partition on an external
    > device seems to be the easier thing to do. Would you agree?


    CERTAINLY NOT!

    --
    Cheers / Saludos,

    Carlos E. R.
    (from 13.1 x86_64 "Bottle" at Telcontar)

  3. #13
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    Default Re: Ownership of encrpted USBdrive with ext4

    I had a separate /data partition that I encrypted using cryptsetup. After system install, I opened my file manager as root (be it dolphin, nautilus, thunar, etc) and set the permissions to it for root and my user, both can read and write in and out of any folder, and the "Others" group (that do not belong to 'root' or 'my-group') couldn't access that partition.
    The good thing is that it stays with it's permissions set even after system re-install.
    openSUSE 13.1

  4. #14
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    Default Re: Ownership of encrpted USBdrive with ext4

    Quote Originally Posted by opensuseinmanila View Post
    I am sorry that I caused a lot of confusion here. But part of the confusion is caused by my interpretation of the documentation.
    I wouldn't worry about it. Every documentation assume a certain level of knowledge, and sometimes this assumption is wrong. But your interpretation was logical and, after all, this documentation is not for programmers, but for the general user. Sometimes the people at the fora (including me) tend to be a bit too much precise, but this is not altogether a bad thing, as it sometimes avoids misinterpretations on the respondent side.

    The way you saw it (device permission) vs the way it is (folder permissions) is not too far apart, as every device partition is mounted as a folder (directory?), and if you set this directory permissions everything under it will in principle have the same permissions by default. Of course, there might be system/security policies that prevent you doing this to key folders like / or /sbin and such.

    The way you changed the permissions with Dolphin in root mode is just like I usually do. For example, when creating a NFS mount point in Yast NFS client for a network share, the new folder is owned by root, even if under /home/$USER. So I change it like you do, if I want to. If the folder already exist, it retains it's permissions.

    On a side note: what's the difference between directories and folders? I don't really know. Maybe there is a huge difference for the techno-wizards, but it was never an issue in my day-to day use of openSUSE - or any other SO for the matter :-).

    Quote Originally Posted by opensuseinmanila View Post
    Apart from that, using FAT for an encrypted partition on an external device seems to be the easier thing to do. Would you agree?
    The problem with FAT is that it is more fragile than ext4, is (AFAIK) limited to 4GB maximum file size, and as mentioned by others, does not implement any kind of permissions. Unfortunately if you need cross-platform compatibility (read a pendrive in windows and linux, for instance), it's the simplest way to go.

    And welcome to the openSUSE community!

  5. #15
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    Default Re: Ownership of encrpted USBdrive with ext4

    On 2014-03-13 22:36, brunomcl wrote:

    > On a side note: what's the difference between directories and folders?


    I only use the word "folder" for email folders - because in some cases,
    no directories are involved.


    > The problem with FAT is that it is more fragile than ext4, is (AFAIK)
    > limited to 4GB maximum file size, and as mentioned by others, does not
    > implement any kind of permissions. Unfortunately if you need
    > cross-platform compatibility (read a pendrive in windows and linux, for
    > instance), it's the simplest way to go.


    Portability is nil when using Linux encryption ;-)

    --
    Cheers / Saludos,

    Carlos E. R.
    (from 13.1 x86_64 "Bottle" at Telcontar)

  6. #16
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    Default Re: Ownership of encrpted USBdrive with ext4

    Quote Originally Posted by brunomcl View Post
    On a side note: what's the difference between directories and folders? I don't really know. Maybe there is a huge difference for the techno-wizards, but it was never an issue in my day-to day use of openSUSE - or any other SO for the matter :-).
    There is no difference. The word "directory" is the term used by Unix since it's beginning. It was also used by MS-DOS (remind the command: DIR). The word "folder" I am not sure off, but the word "map" comes from the desktop metaphore where everything on a computer "desktop" should have it's equivalent in daily (office) live. In Unix/Linux (and not restricted to it) a desktop "map" is implemented as a "directory" on the system level. Thus the desktop (GUI) user may say "map" where the system administrator will use "directory".

    As soon as you want to manage your system as system manager/administrator and then start to read man pages and other documentation, you should be prepared to understand the concept of a "directory" in Unix/Linux.
    Henk van Velden

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