[PATCH v4 1/5] ima: always measure and audit files in policy

[Mimi Zohar]

All files matching a "measure" rule must be included in the IMA
measurement list, even when the file hash cannot be calculated.
Similarly, all files matching an "audit" rule must be audited, even when
the file hash can not be calculated.

The file data hash field contained in the IMA measurement list template
data will contain 0's instead of the actual file hash digest.

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

---
Changelog v4:
- Based on both -EBADF and -EINVAL
- clean up ima_collect_measurement()

 security/integrity/ima/ima_api.c  | 58 +++++++++++++++++++++++----------------
 security/integrity/ima/ima_main.c |  4 +--
 2 files changed, 37 insertions(+), 25 deletions(-)

diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
index c2edba8de35e..bbf3ba8bbb09 100644
--- a/security/integrity/ima/ima_api.c
+++ b/security/integrity/ima/ima_api.c
@@ -199,37 +199,49 @@ int ima_collect_measurement(struct integrity_iint_cache *iint,
 	struct inode *inode = file_inode(file);
 	const char *filename = file->f_path.dentry->d_name.name;
 	int result = 0;
+	int length;
+	void *tmpbuf;
+	u64 i_version;
 	struct {
 		struct ima_digest_data hdr;
 		char digest[IMA_MAX_DIGEST_SIZE];
 	} hash;
 
-	if (!(iint->flags & IMA_COLLECTED)) {
-		u64 i_version = file_inode(file)->i_version;
+	if (iint->flags & IMA_COLLECTED)
+		goto out;
 
-		if (file->f_flags & O_DIRECT) {
-			audit_cause = "failed(directio)";
-			result = -EACCES;
-			goto out;
-		}
+	if (file->f_flags & O_DIRECT) {
+		audit_cause = "failed(directio)";
+		result = -EACCES;
+		goto out;
+	}
 
-		hash.hdr.algo = algo;
-
-		result = (!buf) ?  ima_calc_file_hash(file, &hash.hdr) :
-			ima_calc_buffer_hash(buf, size, &hash.hdr);
-		if (!result) {
-			int length = sizeof(hash.hdr) + hash.hdr.length;
-			void *tmpbuf = krealloc(iint->ima_hash, length,
-						GFP_NOFS);
-			if (tmpbuf) {
-				iint->ima_hash = tmpbuf;
-				memcpy(iint->ima_hash, &hash, length);
-				iint->version = i_version;
-				iint->flags |= IMA_COLLECTED;
-			} else
-				result = -ENOMEM;
-		}
+	i_version = file_inode(file)->i_version;
+	hash.hdr.algo = algo;
+
+	/* Initialize hash digest to 0's in case of failure */
+	memset(&hash.digest, 0, sizeof(hash.digest));
+
+	result = (!buf) ?  ima_calc_file_hash(file, &hash.hdr) :
+		ima_calc_buffer_hash(buf, size, &hash.hdr);
+
+	if (result && result != -EBADF && result != -EINVAL)
+		goto out;
+
+	length = sizeof(hash.hdr) + hash.hdr.length;
+	tmpbuf = krealloc(iint->ima_hash, length, GFP_NOFS);
+	if (!tmpbuf) {
+		result = -ENOMEM;
+		goto out;
 	}
+
+	iint->ima_hash = tmpbuf;
+	memcpy(iint->ima_hash, &hash, length);
+	iint->version = i_version;
+
+	/* Possibly temporary failure due to type of read (eg. DAX, O_DIRECT) */
+	if (result != -EBADF && result != -EINVAL)
+		iint->flags |= IMA_COLLECTED;
 out:
 	if (result)
 		integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode,
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 2aebb7984437..3941371402ff 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -235,7 +235,7 @@ static int process_measurement(struct file *file, char *buf, loff_t size,
 	hash_algo = ima_get_hash_algo(xattr_value, xattr_len);
 
 	rc = ima_collect_measurement(iint, file, buf, size, hash_algo);
-	if (rc != 0) {
+	if (rc != 0 && rc != -EBADF && rc != -EINVAL) {
 		if (file->f_flags & O_DIRECT)
 			rc = (iint->flags & IMA_PERMIT_DIRECTIO) ? 0 : -EACCES;
 		goto out_digsig;
@@ -247,7 +247,7 @@ static int process_measurement(struct file *file, char *buf, loff_t size,
 	if (action & IMA_MEASURE)
 		ima_store_measurement(iint, file, pathname,
 				      xattr_value, xattr_len, pcr);
-	if (action & IMA_APPRAISE_SUBMASK)
+	if ((rc == 0) && (action & IMA_APPRAISE_SUBMASK))
 		rc = ima_appraise_measurement(func, iint, file, pathname,
 					      xattr_value, xattr_len, opened);
 	if (action & IMA_AUDIT)
-- 
2.7.4

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