ima: select ima-buf template for buffer measurement

The default IMA template used for all policy rules is the value set
for CONFIG_IMA_DEFAULT_TEMPLATE if the policy rule does not specify
a template. The default IMA template for buffer measurements should be
'ima-buf' - so that the measured buffer is correctly included in the IMA
measurement log entry.

With the default template format, buffer measurements are added to
the measurement list, but do not include the buffer data, making it
difficult, if not impossible, to validate. Including 'ima-buf'
template records in the measurement list by default, should not impact
existing attestation servers without 'ima-buf' template support.

Initialize a global 'ima-buf' template and select that template,
by default, for buffer measurements.

Signed-off-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

1 files changed, 9 insertions, 15 deletions

diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index a962b23e0429..68956e884403 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -413,7 +413,7 @@ int ima_file_mmap(struct file *file, unsigned long prot)
  */
 int ima_file_mprotect(struct vm_area_struct *vma, unsigned long prot)
 {
-	struct ima_template_desc *template;
+	struct ima_template_desc *template = NULL;
 	struct file *file = vma->vm_file;
 	char filename[NAME_MAX];
 	char *pathbuf = NULL;
@@ -802,7 +802,7 @@ void process_buffer_measurement(struct inode *inode, const void *buf, int size,
 					    .filename = eventname,
 					    .buf = buf,
 					    .buf_len = size};
-	struct ima_template_desc *template = NULL;
+	struct ima_template_desc *template;
 	struct {
 		struct ima_digest_data hdr;
 		char digest[IMA_MAX_DIGEST_SIZE];
@@ -814,6 +814,13 @@ void process_buffer_measurement(struct inode *inode, const void *buf, int size,
 	if (!ima_policy_flag)
 		return;
 
+	template = ima_template_desc_buf();
+	if (!template) {
+		ret = -EINVAL;
+		audit_cause = "ima_template_desc_buf";
+		goto out;
+	}
+
 	/*
 	 * Both LSM hooks and auxilary based buffer measurements are
 	 * based on policy.  To avoid code duplication, differentiate
@@ -832,19 +839,6 @@ void process_buffer_measurement(struct inode *inode, const void *buf, int size,
 	if (!pcr)
 		pcr = CONFIG_IMA_MEASURE_PCR_IDX;
 
-	if (!template) {
-		template = lookup_template_desc("ima-buf");
-		ret = template_desc_init_fields(template->fmt,
-						&(template->fields),
-						&(template->num_fields));
-		if (ret < 0) {
-			pr_err("template %s init failed, result: %d\n",
-			       (strlen(template->name) ?
-				template->name : template->fmt), ret);
-			return;
-		}
-	}
-
 	iint.ima_hash = &hash.hdr;
 	iint.ima_hash->algo = ima_hash_algo;
 	iint.ima_hash->length = hash_digest_size[ima_hash_algo];