linux-kernel - [PATCH 4.4 06/37] Revert "ima: limit file hash setting by user to fix and log modes"

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Date:   Tue,  5 Jun 2018 19:01:11 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Patrick Ohly <patrick.ohly@...el.com>,
        Dmitry Kasatkin <dmitry.kasatkin@...il.com>,
        Mimi Zohar <zohar@...ux.vnet.ibm.com>,
        Mike Rapoport <rppt@...ux.vnet.ibm.com>
Subject: [PATCH 4.4 06/37] Revert "ima: limit file hash setting by user to fix and log modes"

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

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

commit f5acb3dcba1ffb7f0b8cbb9dba61500eea5d610b upstream.

Userspace applications have been modified to write security xattrs,
but they are not context aware.  In the case of security.ima, the
security xattr can be either a file hash or a file signature.
Permitting writing one, but not the other requires the application to
be context aware.

In addition, userspace applications might write files to a staging
area, which might not be in policy, and then change some file metadata
(eg. owner) making it in policy.  As a result, these files are not
labeled properly.

This reverts commit c68ed80c97d9720f51ef31fe91560fdd1e121533, which
prevents writing file hashes as security.ima xattrs.

Requested-by: Patrick Ohly <patrick.ohly@...el.com>
Cc: Dmitry Kasatkin <dmitry.kasatkin@...il.com>
Signed-off-by: Mimi Zohar <zohar@...ux.vnet.ibm.com>
Cc: Mike Rapoport <rppt@...ux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 security/integrity/ima/ima_appraise.c |    8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -383,14 +383,10 @@ int ima_inode_setxattr(struct dentry *de
 	result = ima_protect_xattr(dentry, xattr_name, xattr_value,
 				   xattr_value_len);
 	if (result == 1) {
-		bool digsig;
-
 		if (!xattr_value_len || (xvalue->type >= IMA_XATTR_LAST))
 			return -EINVAL;
-		digsig = (xvalue->type == EVM_IMA_XATTR_DIGSIG);
-		if (!digsig && (ima_appraise & IMA_APPRAISE_ENFORCE))
-			return -EPERM;
-		ima_reset_appraise_flags(d_backing_inode(dentry), digsig);
+		ima_reset_appraise_flags(d_backing_inode(dentry),
+			 (xvalue->type == EVM_IMA_XATTR_DIGSIG) ? 1 : 0);
 		result = 0;
 	}
 	return result;