ima: accept previously set IMA_NEW_FILE

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>
Cc: stable@vger.kernel.org
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index 1fd9539a969dce20d292c70885758945be84acdd..5d0785cfe06387f65a53f84f2832007d77a7932c 100644 (file)
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -207,10 +207,11 @@ 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;
        }