[PATCH 4.9 06/61] Revert "ima: limit file hash setting by user to fix and log modes"

Greg Kroah-Hartman
2018-06-05T17:19:56Z

From: Mimi Zohar <zohar@linux.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@intel.com>
Cc: Dmitry Kasatkin <dmitry.kasatkin@gmail.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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
@@ -389,14 +389,10 @@ 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;