ima: accept previously set IMA_NEW_FILE

commit 1ac202e978e18f045006d75bd549612620c6ec3a upstream.

Modifying the attributes of a file makes ima_inode_post_setattr reset
the IMA cache flags. So if the file, which has just been created,
is opened a second time before the first file descriptor is closed,
verification fails since the security.ima xattr has not been written
yet. We therefore have to look at the IMA_NEW_FILE even if the file
already existed.

With this patch there should no longer be an error when cat tries to
open testfile:

$ rm -f testfile
$ ( echo test >&3 ; touch testfile ; cat testfile ) 3>testfile

A file being new is no reason to accept that it is missing a digital
signature demanded by the policy.

Signed-off-by: Daniel Glöckner <dg@emlix.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 3 insertions, 2 deletions

diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index 389325ac6067..097459830454 100644
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -204,10 +204,11 @@ int ima_appraise_measurement(enum ima_hooks func,
 
                 cause = "missing-hash";
                 status = INTEGRITY_NOLABEL;
-                if (opened & FILE_CREATED) {
+                if (opened & FILE_CREATED)
                         iint->flags |= IMA_NEW_FILE;
+                if ((iint->flags & IMA_NEW_FILE) &&
+                    !(iint->flags & IMA_DIGSIG_REQUIRED))
                         status = INTEGRITY_PASS;
-                }
                 goto out;
         }