ima: per hook cache integrity appraisal status

With the new IMA policy 'appraise_type=' option, different hooks
can require different methods for appraising a file's integrity.

For example, the existing 'ima_appraise_tcb' policy defines a
generic rule, requiring all root files to be appraised, without
specfying the appraisal method.  A more specific rule could require
all kernel modules, for example, to be signed.

appraise fowner=0 func=MODULE_CHECK appraise_type=imasig
appraise fowner=0

As a result, the integrity appraisal results for the same inode, but
for different hooks, could differ.  This patch caches the integrity
appraisal results on a per hook basis.

Changelog v2:
- Rename ima_cache_status() to ima_set_cache_status()
- Rename and move get_appraise_status() to ima_get_cache_status()
Changelog v0:
- include IMA_APPRAISE/APPRAISED_SUBMASK in IMA_DO/DONE_MASK (Dmitry)
- Support independent MODULE_CHECK appraise status.
- fixed IMA_XXXX_APPRAISE/APPRAISED flags

Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@intel.com>

1 files changed, 62 insertions, 9 deletions

diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index 8004332ccb8f..2d4becab8918 100644
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -51,6 +51,62 @@ static int ima_fix_xattr(struct dentry *dentry,
 				      sizeof(iint->ima_xattr), 0);
 }
 
+/* Return specific func appraised cached result */
+enum integrity_status ima_get_cache_status(struct integrity_iint_cache *iint,
+					   int func)
+{
+	switch(func) {
+	case MMAP_CHECK:
+		return iint->ima_mmap_status;
+	case BPRM_CHECK:
+		return iint->ima_bprm_status;
+	case MODULE_CHECK:
+		return iint->ima_module_status;
+	case FILE_CHECK:
+	default:
+		return iint->ima_file_status;
+	}
+}
+
+static void ima_set_cache_status(struct integrity_iint_cache *iint,
+				 int func, enum integrity_status status)
+{
+	switch(func) {
+	case MMAP_CHECK:
+		iint->ima_mmap_status = status;
+		break;
+	case BPRM_CHECK:
+		iint->ima_bprm_status = status;
+		break;
+	case MODULE_CHECK:
+		iint->ima_module_status = status;
+		break;
+	case FILE_CHECK:
+	default:
+		iint->ima_file_status = status;
+		break;
+	}
+}
+
+static void ima_cache_flags(struct integrity_iint_cache *iint, int func)
+{
+	switch(func) {
+	case MMAP_CHECK:
+		iint->flags |= (IMA_MMAP_APPRAISED | IMA_APPRAISED);
+		break;
+	case BPRM_CHECK:
+		iint->flags |= (IMA_BPRM_APPRAISED | IMA_APPRAISED);
+		break;
+	case MODULE_CHECK:
+		iint->flags |= (IMA_MODULE_APPRAISED | IMA_APPRAISED);
+		break;
+	case FILE_CHECK:
+	default:
+		iint->flags |= (IMA_FILE_APPRAISED | IMA_APPRAISED);
+		break;
+	}
+}
+
 /*
  * ima_appraise_measurement - appraise file measurement
  *
@@ -59,7 +115,7 @@ static int ima_fix_xattr(struct dentry *dentry,
  *
  * Return 0 on success, error code otherwise
  */
-int ima_appraise_measurement(struct integrity_iint_cache *iint,
+int ima_appraise_measurement(int func, struct integrity_iint_cache *iint,
 			     struct file *file, const unsigned char *filename)
 {
 	struct dentry *dentry = file->f_dentry;
@@ -75,9 +131,6 @@ int ima_appraise_measurement(struct integrity_iint_cache *iint,
 	if (!inode->i_op->getxattr)
 		return INTEGRITY_UNKNOWN;
 
-	if (iint->flags & IMA_APPRAISED)
-		return iint->ima_status;
-
 	rc = vfs_getxattr_alloc(dentry, XATTR_NAME_IMA, (char **)&xattr_value,
 				0, GFP_NOFS);
 	if (rc <= 0) {
@@ -99,7 +152,6 @@ int ima_appraise_measurement(struct integrity_iint_cache *iint,
 			cause = "invalid-HMAC";
 		goto out;
 	}
-
 	switch (xattr_value->type) {
 	case IMA_XATTR_DIGEST:
 		if (iint->flags & IMA_DIGSIG_REQUIRED) {
@@ -148,9 +200,9 @@ out:
 		integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, filename,
 				    op, cause, rc, 0);
 	} else {
-		iint->flags |= IMA_APPRAISED;
+		ima_cache_flags(iint, func);
 	}
-	iint->ima_status = status;
+	ima_set_cache_status(iint, func, status);
 	kfree(xattr_value);
 	return status;
 }
@@ -196,10 +248,11 @@ void ima_inode_post_setattr(struct dentry *dentry)
 	must_appraise = ima_must_appraise(inode, MAY_ACCESS, POST_SETATTR);
 	iint = integrity_iint_find(inode);
 	if (iint) {
+		iint->flags &= ~(IMA_APPRAISE | IMA_APPRAISED |
+				 IMA_APPRAISE_SUBMASK | IMA_APPRAISED_SUBMASK |
+				 IMA_ACTION_FLAGS);
 		if (must_appraise)
 			iint->flags |= IMA_APPRAISE;
-		else
-			iint->flags &= ~(IMA_APPRAISE | IMA_APPRAISED);
 	}
 	if (!must_appraise)
 		rc = inode->i_op->removexattr(dentry, XATTR_NAME_IMA);