Patch "ima: relax requiring a file signature for new files with zero length" has been added to the 3.18-stable tree

Patch "ima: relax requiring a file signature for new files with zero length" has been added to the 3.18-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    ima: relax requiring a file signature for new files with zero length

to the 3.18-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     ima-relax-requiring-a-file-signature-for-new-files-with-zero-length.patch
and it can be found in the queue-3.18 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Mon Mar 19 10:11:52 CET 2018
From: Mimi Zohar <zohar@linux.vnet.ibm.com>
Date: Wed, 8 Nov 2017 07:38:28 -0500
Subject: ima: relax requiring a file signature for new files with zero length

From: Mimi Zohar <zohar@linux.vnet.ibm.com>


[ Upstream commit b7e27bc1d42e8e0cc58b602b529c25cd0071b336 ]

Custom policies can require file signatures based on LSM labels.  These
files are normally created and only afterwards labeled, requiring them
to be signed.

Instead of requiring file signatures based on LSM labels, entire
filesystems could require file signatures.  In this case, we need the
ability of writing new files without requiring file signatures.

The definition of a "new" file was originally defined as any file with
a length of zero.  Subsequent patches redefined a "new" file to be based
on the FILE_CREATE open flag.  By combining the open flag with a file
size of zero, this patch relaxes the file signature requirement.

Fixes: 1ac202e978e1 ima: accept previously set IMA_NEW_FILE
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 security/integrity/ima/ima_appraise.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -206,7 +206,8 @@ int ima_appraise_measurement(int func, s
 		if (opened & FILE_CREATED)
 			iint->flags |= IMA_NEW_FILE;
 		if ((iint->flags & IMA_NEW_FILE) &&
-		    !(iint->flags & IMA_DIGSIG_REQUIRED))
+		    (!(iint->flags & IMA_DIGSIG_REQUIRED) ||
+		     (inode->i_size == 0)))
 			status = INTEGRITY_PASS;
 		goto out;
 	}


Patches currently in stable-queue which might be from zohar@linux.vnet.ibm.com are

queue-3.18/ima-relax-requiring-a-file-signature-for-new-files-with-zero-length.patch