ima: use full pathnames in measurement list

The IMA measurement list contains filename hints, which can be
ambigious without the full pathname.  This patch replaces the
filename hint with the full pathname, simplifying for userspace
the correlating of file hash measurements with files.

Change log v1:
- Revert to short filenames, when full pathname is longer than IMA
  measurement buffer size. (Based on Dmitry's review)

Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

security/integrity/ima/ima_api.c

@@ -175,7 +175,9 @@ void ima_store_measurement(struct integrity_iint_cache *iint,
 	}
 	memset(&entry->template, 0, sizeof(entry->template));
 	memcpy(entry->template.digest, iint->digest, IMA_DIGEST_SIZE);
-	strncpy(entry->template.file_name, filename, IMA_EVENT_NAME_LEN_MAX);
+	strcpy(entry->template.file_name,
+	       (strlen(filename) > IMA_EVENT_NAME_LEN_MAX) ?
+	       file->f_dentry->d_name.name : filename);
 
 	result = ima_store_template(entry, violation, inode);
 	if (!result || result == -EEXIST)

security/integrity/ima/ima_main.c

@@ -54,6 +54,7 @@ static void ima_rdwr_violation_check(struct file *file)
 	fmode_t mode = file->f_mode;
 	int rc;
 	bool send_tomtou = false, send_writers = false;
+	unsigned char *pathname = NULL, *pathbuf = NULL;
 
 	if (!S_ISREG(inode->i_mode) || !ima_initialized)
 		return;
@@ -75,12 +76,27 @@ static void ima_rdwr_violation_check(struct file *file)
 out:
 	mutex_unlock(&inode->i_mutex);
 
+	if (!send_tomtou && !send_writers)
+		return;
+
+	/* We will allow 11 spaces for ' (deleted)' to be appended */
+	pathbuf = kmalloc(PATH_MAX + 11, GFP_KERNEL);
+	if (pathbuf) {
+		pathname = d_path(&file->f_path, pathbuf, PATH_MAX + 11);
+		if (IS_ERR(pathname))
+			pathname = NULL;
+		else if (strlen(pathname) > IMA_EVENT_NAME_LEN_MAX)
+			pathname = NULL;
+	}
 	if (send_tomtou)
-		ima_add_violation(inode, dentry->d_name.name, "invalid_pcr",
-				  "ToMToU");
+		ima_add_violation(inode,
+				  !pathname ? dentry->d_name.name : pathname,
+				  "invalid_pcr", "ToMToU");
 	if (send_writers)
-		ima_add_violation(inode, dentry->d_name.name, "invalid_pcr",
-				  "open_writers");
+		ima_add_violation(inode,
+				  !pathname ? dentry->d_name.name : pathname,
+				  "invalid_pcr", "open_writers");
+	kfree(pathbuf);
 }
 
 static void ima_check_last_writer(struct integrity_iint_cache *iint,
@@ -123,6 +139,7 @@ static int process_measurement(struct file *file, const unsigned char *filename,
 {
 	struct inode *inode = file->f_dentry->d_inode;
 	struct integrity_iint_cache *iint;
+	unsigned char *pathname = NULL, *pathbuf = NULL;
 	int rc = 0;
 
 	if (!ima_initialized || !S_ISREG(inode->i_mode))
@@ -147,8 +164,21 @@ static int process_measurement(struct file *file, const unsigned char *filename,
 		goto out;
 
 	rc = ima_collect_measurement(iint, file);
-	if (!rc)
-		ima_store_measurement(iint, file, filename);
+	if (rc != 0)
+		goto out;
+
+	if (function != BPRM_CHECK) {
+		/* We will allow 11 spaces for ' (deleted)' to be appended */
+		pathbuf = kmalloc(PATH_MAX + 11, GFP_KERNEL);
+		if (pathbuf) {
+			pathname =
+			    d_path(&file->f_path, pathbuf, PATH_MAX + 11);
+			if (IS_ERR(pathname))
+				pathname = NULL;
+		}
+	}
+	ima_store_measurement(iint, file, !pathname ? filename : pathname);
+	kfree(pathbuf);
 out:
 	mutex_unlock(&iint->mutex);
 	return rc;