[SRU][Xenial][PATCH 1/1] Revert "ima: limit file hash setting by user to fix and log modes"

[Joseph Salisbury]

From: Mimi Zohar <zohar at linux.vnet.ibm.com>

BugLink: http://bugs.launchpad.net/bugs/1771826

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 at intel.com>
Cc: Dmitry Kasatkin <dmitry.kasatkin at gmail.com>
Signed-off-by: Mimi Zohar <zohar at linux.vnet.ibm.com>
(cherry picked from commit f5acb3dcba1ffb7f0b8cbb9dba61500eea5d610b)
Signed-off-by: Joseph Salisbury <joseph.salisbury at canonical.com>
---
 security/integrity/ima/ima_appraise.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index d62ae31..80f2c6d 100644
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -384,14 +384,10 @@ int ima_inode_setxattr(struct dentry *dentry, const char *xattr_name,
 	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;
-- 
2.7.4