[1/2] ima-evm-utils: limit "remain unprocessed data" messages
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Message ID 1562591750-14234-1-git-send-email-zohar@linux.ibm.com
State New
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  • [1/2] ima-evm-utils: limit "remain unprocessed data" messages
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Commit Message

Mimi Zohar July 8, 2019, 1:15 p.m. UTC
New, unknown template formats containing unknown fields are not
processed, resulting in "remain unprocessed data" messages.  Processing
these unknown fields is unnecessary for walking the measurement list to
re-calculate the PCRs.

The "remain unproccessed data" may also be emitted for malformed, known
template records.

This patch limits the number of messages emitted to once per template
format and includes the template name in the message.

Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
---
 src/evmctl.c | 37 +++++++++++++++++++++++++++++++++++--
 1 file changed, 35 insertions(+), 2 deletions(-)

Patch
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diff --git a/src/evmctl.c b/src/evmctl.c
index 7ce20225c89d..f6046637d8f6 100644
--- a/src/evmctl.c
+++ b/src/evmctl.c
@@ -1411,6 +1411,34 @@  void ima_show(struct template_entry *entry)
 	log_debug_dump(entry->header.digest, sizeof(entry->header.digest));
 }
 
+/*
+ * Keep track of unknown or malformed template names.
+ *
+ * Return 1 for found, return 0 for not found.
+ */
+static int lookup_template_name_entry(char *template_name)
+{
+	struct template_name_entry {
+		struct template_name_entry *next;
+		char name[];
+	} *entry;
+	static struct template_name_entry *template_names = NULL;
+
+	for (entry = template_names; entry != NULL; entry = entry->next) {
+		if (strcmp(entry->name, template_name) == 0)
+			return 1;
+	}
+
+	entry = malloc(sizeof(struct template_name_entry) +
+			strlen(template_name) + 1);
+	if (entry) {
+		strcpy(entry->name, template_name);
+		entry->next = template_names;
+		template_names = entry;
+	}
+	return 0;
+}
+
 void ima_ng_show(struct template_entry *entry)
 {
 	uint8_t *fieldp = entry->template;
@@ -1418,6 +1446,7 @@  void ima_ng_show(struct template_entry *entry)
 	int total_len = entry->template_len, digest_len, len, sig_len;
 	uint8_t *digest, *sig = NULL;
 	char *algo, *path;
+	int found;
 	int err;
 
 	/* get binary digest */
@@ -1487,8 +1516,12 @@  void ima_ng_show(struct template_entry *entry)
 			log_info("\n");
 	}
 
-	if (total_len)
-		log_err("Remain unprocessed data: %d\n", total_len);
+	if (total_len) {
+		found = lookup_template_name_entry(entry->name);
+		if (!found)
+			log_err("Template \"%s\" contains unprocessed data: "
+				 "%d bytes\n", entry->name, total_len);
+	}
 }
 
 static int ima_measurement(const char *file)