Re: Write protection on SD cards

From	Lusotec <nomail@nomail.not>
Newsgroups	comp.os.linux.security
Subject	Re: Write protection on SD cards
Followup-To	comp.os.linux.security
Date	2011-11-01 21:48 +0000
Organization	A noiseless patient Spider
Message-ID	<j8ppfe$elb$1@dont-email.me> (permalink)
References	<9hb396F3fcU1@mid.individual.net>

Followups directed to: comp.os.linux.security

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Günther Schwarz wrote:
> Most SD flash cards do have a little plastic thing for write protection.
> As far as I understand this is not connected to the electronics of the
> card but rather informs the card reader which in turn sends a read-only
> flag to the host (some readers do ignore the switch). How secure is this
> with Linux as the host OS? Will it be possible to force a mount with rw
> option?
> The background of my question is that I could make good use of a read-
> only device other than a optical disk on some systems. USB sticks with a
> switch for write protection seem to be as rare as hen's teeth today.
> 
> Günther

Linux respects the write protection of SD cards

I get this line "sd 6:0:0:0: [sde] Write Protect is on" in dmesg after 
inserting a write protected SD card in this GNU/Linux system.

Trying to mount as RW gives the produces the following message.

$ LANGUAGE=C mount -o rw /dev/sdb1 /mnt/tmp/
mount: block device /dev/sdb1 is write-protected, mounting read-only

I don't know If there is a way to force Linux to ignore the write 
protection.

Regards.

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Thread

Write protection on SD cards Günther Schwarz <strap@gmx.de> - 2011-11-01 20:31 +0000
  Re: Write protection on SD cards Lusotec <nomail@nomail.not> - 2011-11-01 21:48 +0000
  Re: Write protection on SD cards Tobias Blass <tobiasblass@gmx.net> - 2011-11-02 13:10 +0000
    Re: Write protection on SD cards Günther Schwarz <strap@gmx.de> - 2011-11-05 11:51 +0000
      Re: Write protection on SD cards mcanswer@mcanswer.pl - 2011-12-17 07:51 +0100
        Re: Write protection on SD cards Günther Schwarz <strap@gmx.de> - 2011-12-17 16:32 +0000

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