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ima: accept previously set IMA_NEW_FILE

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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>
This commit is contained in:
Daniel Glöckner 2017-02-24 15:05:14 +01:00 committed by Mimi Zohar
parent bad4417b69
commit 1ac202e978
1 changed files with 3 additions and 2 deletions
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5
security/integrity/ima/ima_appraise.c
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@ -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;
}