linux-kernel - [PATCH AUTOSEL for 3.18 63/63] ima: relax requiring a file signature for new files with zero length

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20180303223228.27323-63-alexander.levin@microsoft.com>
Date:   Sat, 3 Mar 2018 22:33:50 +0000
From:   Sasha Levin <Alexander.Levin@...rosoft.com>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
CC:     Mimi Zohar <zohar@...ux.vnet.ibm.com>,
        Sasha Levin <Alexander.Levin@...rosoft.com>
Subject: [PATCH AUTOSEL for 3.18 63/63] ima: relax requiring a file signature
 for new files with zero length

From: Mimi Zohar <zohar@...ux.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@...ux.vnet.ibm.com>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
---
 security/integrity/ima/ima_appraise.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index ee7618115756..0bdf01decb63 100644
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -206,7 +206,8 @@ int ima_appraise_measurement(int func, struct integrity_iint_cache *iint,
 		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;
 	}
-- 
2.14.1