|From:||David Safford <safford-AT-watson.ibm.com>|
|To:||Pavel Machek <pavel-AT-ucw.cz>|
|Subject:||Re: [Patch 3/7] integrity: EVM as an integrity service provider|
|Date:||Mon, 26 Mar 2007 13:55:15 -0400|
|Cc:||Andrew Morton <akpm-AT-linux-foundation.org>, Mimi Zohar <zohar-AT-linux.vnet.ibm.com>, linux-kernel-AT-vger.kernel.org, serue-AT-linux.vnet.ibm.com, kjhall-AT-linux.vnet.ibm.com, zohar-AT-us.ibm.com|
On Sun, 2007-03-25 at 12:13 +0000, Pavel Machek wrote: > > > + The Extended Verification Module is an integrity provider. > > > + An extensible set of extended attributes, as defined in > > > + /etc/evm.conf, are HMAC protected against modification > > > + using the TPM's KERNEL ROOT KEY, if configured, or with a > > > + pass-phrase. Possible extended attributes include authenticity, > > > + integrity, and revision level. > > What is identity provider good for? Can you explain it a bit more, or > perhaps point to Doc*/ somewhere? > Pavel There are some papers and related userspace code at http://www.research.ibm.com/gsal/tcpa which describe the architecture in more detail, but basically this integrity provider is designed to complement mandatory access control systems like selinux and slim. Such systems can protect a running system against on-line attacks, but do not protect against off-line attacks (booting Knoppix and changing executables or their selinux labels), or against attacks which find weaknesses in the kernel or the LSM module itself. Using a TPM or passphrase, EVM can verify the integrity of all files (including the kernel and initrd) and their labels before they are referenced. Using a TPM, EVM/IMA can attest to the integrity of all files to a third party, even if the kernel or modules have been compromised. (An attack can block the attestation, but cannot forge valid TPM signatures.) In response to customer demand, we are actively working to develop and test this attestation in enterprise server environments, integrated with both selinux and AppArmor. dave
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