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Re: [PATCH] X.509: Partially revert patch to add validation against IMA MOK keyring

From David Howells <dhowells@redhat.com>
Newsgroups linux.kernel
Subject Re: [PATCH] X.509: Partially revert patch to add validation against IMA MOK keyring
Date 2016-01-12 11:10 +0100
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Mimi Zohar <zohar@linux.vnet.ibm.com> wrote:

> The IMA MOK and blacklist are restricted to "public_key_restrict_link".
> Does this only allow keys signed by keys on the respective keyring or
> also by the system keyring? 

As my patches stand, the following are implemented:

 (1) public_key_restrict_link() restricts to asymmetric keys that are signed
     by a CA in the specified keyring.  It returns -ENOKEY if no matching key
     is found rather than -EKEYREJECTED, however, so you can call it several
     times for different keyrings.  -EKEYREJECTED is only returned if a
     signature check fails.  This is used by the following two functions.

 (2) restrict_link_by_system_trusted() restricts to asymmetric keys that are
     signed by a CA in the system keyring.  This ignores the keyring argument
     it is given.

     Note that the system_trusted_keyring is then no longer exported because
     verify_pkcs7_signature() is also in certs/system_keyring.c and uses that
     by default if NULL is passed.

 (3) restrict_link_by_ima_mok() restricts to asymmetric keys signed by a CA in
     either .system_keyring or .ima_mok.

So the trusted keyrings are then restricted as follows:

 (1) .system_keyring uses restrict_link_by_system_trusted() - though it lacks
     any sort of write permission, so it's currently moot.  It could just as
     well be replaced with a function that just returns -EPERM.

 (2) .ima_mok should be using restrict_link_by_system_trusted(), but I failed
     to update this when I split the public_key_restrict_link() function.
     I've updated this in my patch.  This would then be correct according to
     Petko's commit log:

	To successfully import a key into .ima_mok it must be signed by a
	key which CA is in .system keyring.

     However, from what Petko says, this is wrong and it should instead be
     using restrict_link_by_ima_mok().

 (3) .ima_blacklist should be using restrict_link_by_system_trusted() also.
     I've no idea whether additions to this should be permitted by keys in
     .ima_mok also.

 (4) .ima uses restrict_link_by_ima_mok(), as per:

	On turn any key that needs to go in .ima keyring must be signed by CA
	in either .system or .ima_mok keyrings.
    
 (5) .evm is not restricted by my patches.  This is a mistake on my part - but
     I'm not sure what the restriction actually needs to be as it's not
     mentioned in Petko's commit message.  Presumably it needs the same as
     .ima.

David

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Thread

[PATCH] X.509: Partially revert patch to add validation against IMA  MOK keyring David Howells <dhowells@redhat.com> - 2016-01-06 14:50 +0100
  Re: [PATCH] X.509: Partially revert patch to add validation against  IMA MOK keyring James Morris <jmorris@namei.org> - 2016-01-07 01:10 +0100
  Re: [PATCH] X.509: Partially revert patch to add validation against IMA MOK keyring David Howells <dhowells@redhat.com> - 2016-01-07 01:40 +0100
    Re: [PATCH] X.509: Partially revert patch to add validation against  IMA MOK keyring Mimi Zohar <zohar@linux.vnet.ibm.com> - 2016-01-07 03:20 +0100
      Re: [PATCH] X.509: Partially revert patch to add validation against  IMA MOK keyring Mimi Zohar <zohar@linux.vnet.ibm.com> - 2016-01-07 04:30 +0100
    Re: [PATCH] X.509: Partially revert patch to add validation against  IMA MOK keyring Mimi Zohar <zohar@linux.vnet.ibm.com> - 2016-01-07 16:40 +0100
      Re: [PATCH] X.509: Partially revert patch to add validation against  IMA MOK keyring James Morris <jmorris@namei.org> - 2016-01-10 11:40 +0100
        Re: [PATCH] X.509: Partially revert patch to add validation against  IMA MOK keyring Mimi Zohar <zohar@linux.vnet.ibm.com> - 2016-01-10 14:30 +0100
          Re: [PATCH] X.509: Partially revert patch to add validation against IMA MOK keyring David Howells <dhowells@redhat.com> - 2016-01-10 18:50 +0100
            Re: [PATCH] X.509: Partially revert patch to add validation against IMA MOK keyring David Howells <dhowells@redhat.com> - 2016-01-10 21:40 +0100
              Re: [PATCH] X.509: Partially revert patch to add validation against  IMA MOK keyring Mimi Zohar <zohar@linux.vnet.ibm.com> - 2016-01-11 01:00 +0100
                Re: [PATCH] X.509: Partially revert patch to add validation against IMA MOK keyring David Howells <dhowells@redhat.com> - 2016-01-12 01:50 +0100
                Re: [PATCH] X.509: Partially revert patch to add validation against IMA MOK keyring  David Howells <dhowells@redhat.com> - 2016-01-12 03:10 +0100
                Re: [PATCH] X.509: Partially revert patch to add validation against  IMA MOK keyring Mimi Zohar <zohar@linux.vnet.ibm.com> - 2016-01-12 04:40 +0100
                Re: [PATCH] X.509: Partially revert patch to add validation against IMA MOK keyring David Howells <dhowells@redhat.com> - 2016-01-12 11:10 +0100
                Re: [PATCH] X.509: Partially revert patch to add validation against  IMA MOK keyring Mimi Zohar <zohar@linux.vnet.ibm.com> - 2016-01-12 14:30 +0100
                Re: [PATCH] X.509: Partially revert patch to add validation against IMA MOK keyring David Howells <dhowells@redhat.com> - 2016-01-12 15:00 +0100
                Re: [PATCH] X.509: Partially revert patch to add validation against  IMA MOK keyring Mimi Zohar <zohar@linux.vnet.ibm.com> - 2016-01-12 16:20 +0100
                Re: [PATCH] X.509: Partially revert patch to add validation against IMA MOK keyring David Howells <dhowells@redhat.com> - 2016-01-12 17:00 +0100
                Re: [PATCH] X.509: Partially revert patch to add validation against  IMA MOK keyring Mimi Zohar <zohar@linux.vnet.ibm.com> - 2016-01-12 17:10 +0100
                Re: [PATCH] X.509: Partially revert patch to add validation against  IMA MOK keyring Petko Manolov <petkan@mip-labs.com> - 2016-01-12 15:20 +0100
            Re: [PATCH] X.509: Partially revert patch to add validation against  IMA MOK keyring Petko Manolov <petkan@mip-labs.com> - 2016-01-10 21:40 +0100
              Re: [PATCH] X.509: Partially revert patch to add validation against IMA MOK keyring David Howells <dhowells@redhat.com> - 2016-01-12 02:40 +0100
                Re: [PATCH] X.509: Partially revert patch to add validation against  IMA MOK keyring Petko Manolov <petkan@mip-labs.com> - 2016-01-12 17:20 +0100
                Re: [PATCH] X.509: Partially revert patch to add validation against IMA MOK keyring David Howells <dhowells@redhat.com> - 2016-01-12 18:10 +0100
                Re: [PATCH] X.509: Partially revert patch to add validation against  IMA MOK keyring Petko Manolov <petkan@mip-labs.com> - 2016-01-13 17:40 +0100
                Re: [PATCH] X.509: Partially revert patch to add validation against  IMA MOK keyring Mimi Zohar <zohar@linux.vnet.ibm.com> - 2016-01-13 19:00 +0100
                Re: [PATCH] X.509: Partially revert patch to add validation against  IMA MOK keyring Petko Manolov <petkan@mip-labs.com> - 2016-01-13 19:10 +0100
                Re: [PATCH] X.509: Partially revert patch to add validation against IMA MOK keyring David Howells <dhowells@redhat.com> - 2016-01-13 19:20 +0100
                Re: [PATCH] X.509: Partially revert patch to add validation against  IMA MOK keyring Petko Manolov <petkan@mip-labs.com> - 2016-01-13 19:40 +0100
                Re: [PATCH] X.509: Partially revert patch to add validation against  IMA MOK keyring Mimi Zohar <zohar@linux.vnet.ibm.com> - 2016-01-13 20:00 +0100
                Re: [PATCH] X.509: Partially revert patch to add validation against  IMA MOK keyring Petko Manolov <petkan@mip-labs.com> - 2016-01-13 20:20 +0100

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