ima: do not send field length to userspace for digest of ima template

This patch defines a new value for the 'ima_show_type' enumerator (IMA_SHOW_BINARY_NO_FIELD_LEN) to prevent that the field length is transmitted through the 'binary_runtime_measurements' interface for the digest field of the 'ima' template. Fixes commit: 3ce1217 ima: define template fields library and new helpers Signed-off-by: Roberto Sassu <[email protected]> Signed-off-by: Mimi Zohar <[email protected]>
wolfgar · Nov 25, 2013 · 3e8e550 · 3e8e550
1 parent b6f8f16
commit 3e8e550
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Showing 3 changed files with 18 additions and 5 deletions.
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
@@ -26,7 +26,8 @@
 
 #include "../integrity.h"
 
-enum ima_show_type { IMA_SHOW_BINARY, IMA_SHOW_ASCII };
+enum ima_show_type { IMA_SHOW_BINARY, IMA_SHOW_BINARY_NO_FIELD_LEN,
+		     IMA_SHOW_ASCII };
 enum tpm_pcrs { TPM_PCR0 = 0, TPM_PCR8 = 8 };
 
 /* digest size for IMA, fits SHA1 or MD5 */

diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
@@ -120,6 +120,7 @@ static int ima_measurements_show(struct seq_file *m, void *v)
 	struct ima_template_entry *e;
 	int namelen;
 	u32 pcr = CONFIG_IMA_MEASURE_PCR_IDX;
+	bool is_ima_template = false;
 	int i;
 
 	/* get entry */
@@ -145,14 +146,21 @@ static int ima_measurements_show(struct seq_file *m, void *v)
 	ima_putc(m, e->template_desc->name, namelen);
 
 	/* 5th:  template length (except for 'ima' template) */
-	if (strcmp(e->template_desc->name, IMA_TEMPLATE_IMA_NAME) != 0)
+	if (strcmp(e->template_desc->name, IMA_TEMPLATE_IMA_NAME) == 0)
+		is_ima_template = true;
+
+	if (!is_ima_template)
 		ima_putc(m, &e->template_data_len,
 			 sizeof(e->template_data_len));
 
 	/* 6th:  template specific data */
 	for (i = 0; i < e->template_desc->num_fields; i++) {
-		e->template_desc->fields[i]->field_show(m, IMA_SHOW_BINARY,
-							&e->template_data[i]);
+		enum ima_show_type show = IMA_SHOW_BINARY;
+		struct ima_template_field *field = e->template_desc->fields[i];
+
+		if (is_ima_template && strcmp(field->field_id, "d") == 0)
+			show = IMA_SHOW_BINARY_NO_FIELD_LEN;
+		field->field_show(m, show, &e->template_data[i]);
 	}
 	return 0;
 }

diff --git a/security/integrity/ima/ima_template_lib.c b/security/integrity/ima/ima_template_lib.c
@@ -109,9 +109,12 @@ static void ima_show_template_data_binary(struct seq_file *m,
 					  enum data_formats datafmt,
 					  struct ima_field_data *field_data)
 {
-	ima_putc(m, &field_data->len, sizeof(u32));
+	if (show != IMA_SHOW_BINARY_NO_FIELD_LEN)
+		ima_putc(m, &field_data->len, sizeof(u32));
+
 	if (!field_data->len)
 		return;
+
 	ima_putc(m, field_data->data, field_data->len);
 }
 
@@ -125,6 +128,7 @@ static void ima_show_template_field_data(struct seq_file *m,
 		ima_show_template_data_ascii(m, show, datafmt, field_data);
 		break;
 	case IMA_SHOW_BINARY:
+	case IMA_SHOW_BINARY_NO_FIELD_LEN:
 		ima_show_template_data_binary(m, show, datafmt, field_data);
 		break;
 	default: