Category Archives: mandatory-access-control

SMACK LSM Module behaves strangely

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I want the following:

  1. I want to use openssl to change the keys. So, I created the directory “/etc/keys” which I labelled “keys“. I created a file “key” with same access “keys” and another key file “forbiddenkey” with access “forbidden” under the directory “etc/keys“.
  2. I made the openssl command execute as “secure“.
  3. I made the following rules
    secure keys rw
    secure forbidden –
  4. I tested the rules as shown in the figure below and they seem to work.

smack image

  1. But when I tried to actually run the command it didn’t work even though the WRITE access is allowed to /etc/keys and /etc/keys/key

    openssl rand 32 > /etc/keys/key

The error message is as follows

-bash: /etc/keys/key: Permission denied

The audit message is as follows

VirtualBox kernel: [ 1274.037659] audit: type=1400 audit(1500117397.021:8): lsm=SMACK fn=smack_inode_getattr action=denied subject=”_” object=”keys” requested=r pid=2574 comm=”pool” path=”/etc/keys” dev=”sda1″ ino=3932692

It’s strange that I ran openssl with execute “secure” as subject but I get in audit as “floor(_)”. Can anyone identify the mistake?

Greets,
Satya

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