ima: define template fields library and new helpers
This patch defines a library containing two initial template fields,
inode digest (d) and file name (n), the 'ima' template descriptor,
whose format is 'd|n', and two helper functions,
ima_write_template_field_data() and ima_show_template_field_data().
Changelog:
- replace ima_eventname_init() parameter NULL checking with BUG_ON.
(suggested by Mimi)
- include "new template fields for inode digest (d) and file name (n)"
definitions to fix a compiler warning. - Mimi
- unnecessary to prefix static function names with 'ima_'. remove
prefix to resolve Lindent formatting changes. - Mimi
- abbreviated/removed inline comments - Mimi
- always send the template field length - Mimi
Signed-off-by: Roberto Sassu <roberto.sassu@polito.it>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
diff --git a/security/integrity/ima/ima_template_lib.c b/security/integrity/ima/ima_template_lib.c
new file mode 100644
index 0000000..e13fc7c
--- /dev/null
+++ b/security/integrity/ima/ima_template_lib.c
@@ -0,0 +1,193 @@
+/*
+ * Copyright (C) 2013 Politecnico di Torino, Italy
+ * TORSEC group -- http://security.polito.it
+ *
+ * Author: Roberto Sassu <roberto.sassu@polito.it>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation, version 2 of the
+ * License.
+ *
+ * File: ima_template_lib.c
+ * Library of supported template fields.
+ */
+#include "ima_template_lib.h"
+
+enum data_formats { DATA_FMT_DIGEST = 0, DATA_FMT_EVENT_NAME, DATA_FMT_STRING };
+static int ima_write_template_field_data(const void *data, const u32 datalen,
+ enum data_formats datafmt,
+ struct ima_field_data *field_data)
+{
+ u8 *buf, *buf_ptr;
+ u32 buflen;
+
+ switch (datafmt) {
+ case DATA_FMT_EVENT_NAME:
+ buflen = IMA_EVENT_NAME_LEN_MAX + 1;
+ break;
+ case DATA_FMT_STRING:
+ buflen = datalen + 1;
+ break;
+ default:
+ buflen = datalen;
+ }
+
+ buf = kzalloc(buflen, GFP_KERNEL);
+ if (!buf)
+ return -ENOMEM;
+
+ memcpy(buf, data, datalen);
+
+ /*
+ * Replace all space characters with underscore for event names and
+ * strings. This avoid that, during the parsing of a measurements list,
+ * filenames with spaces or that end with the suffix ' (deleted)' are
+ * split into multiple template fields (the space is the delimitator
+ * character for measurements lists in ASCII format).
+ */
+ if (datafmt == DATA_FMT_EVENT_NAME || datafmt == DATA_FMT_STRING) {
+ for (buf_ptr = buf; buf_ptr - buf < datalen; buf_ptr++)
+ if (*buf_ptr == ' ')
+ *buf_ptr = '_';
+ }
+
+ field_data->data = buf;
+ field_data->len = buflen;
+ return 0;
+}
+
+static void ima_show_template_data_ascii(struct seq_file *m,
+ enum ima_show_type show,
+ enum data_formats datafmt,
+ struct ima_field_data *field_data)
+{
+ switch (datafmt) {
+ case DATA_FMT_DIGEST:
+ ima_print_digest(m, field_data->data, field_data->len);
+ break;
+ case DATA_FMT_STRING:
+ seq_printf(m, "%s", field_data->data);
+ break;
+ default:
+ break;
+ }
+}
+
+static void ima_show_template_data_binary(struct seq_file *m,
+ enum ima_show_type show,
+ enum data_formats datafmt,
+ struct ima_field_data *field_data)
+{
+ ima_putc(m, &field_data->len, sizeof(u32));
+ if (!field_data->len)
+ return;
+ ima_putc(m, field_data->data, field_data->len);
+}
+
+static void ima_show_template_field_data(struct seq_file *m,
+ enum ima_show_type show,
+ enum data_formats datafmt,
+ struct ima_field_data *field_data)
+{
+ switch (show) {
+ case IMA_SHOW_ASCII:
+ ima_show_template_data_ascii(m, show, datafmt, field_data);
+ break;
+ case IMA_SHOW_BINARY:
+ ima_show_template_data_binary(m, show, datafmt, field_data);
+ break;
+ default:
+ break;
+ }
+}
+
+void ima_show_template_digest(struct seq_file *m, enum ima_show_type show,
+ struct ima_field_data *field_data)
+{
+ ima_show_template_field_data(m, show, DATA_FMT_DIGEST, field_data);
+}
+
+void ima_show_template_string(struct seq_file *m, enum ima_show_type show,
+ struct ima_field_data *field_data)
+{
+ ima_show_template_field_data(m, show, DATA_FMT_STRING, field_data);
+}
+
+/*
+ * This function writes the digest of an event.
+ */
+int ima_eventdigest_init(struct integrity_iint_cache *iint, struct file *file,
+ const unsigned char *filename,
+ struct ima_field_data *field_data)
+{
+ struct {
+ struct ima_digest_data hdr;
+ char digest[IMA_MAX_DIGEST_SIZE];
+ } hash;
+ u8 *cur_digest = hash.hdr.digest;
+ u32 cur_digestsize = IMA_DIGEST_SIZE;
+ struct inode *inode;
+ int result;
+
+ memset(&hash, 0, sizeof(hash));
+
+ if (!iint) /* recording a violation. */
+ goto out;
+
+ if (iint->ima_hash->algo == ima_hash_algo) {
+ cur_digest = iint->ima_hash->digest;
+ cur_digestsize = iint->ima_hash->length;
+ goto out;
+ }
+
+ if (!file) /* missing info to re-calculate the digest */
+ return -EINVAL;
+
+ inode = file_inode(file);
+ hash.hdr.algo = ima_hash_algo;
+ result = ima_calc_file_hash(file, &hash.hdr);
+ if (result) {
+ integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode,
+ filename, "collect_data",
+ "failed", result, 0);
+ return result;
+ }
+out:
+ return ima_write_template_field_data(cur_digest, cur_digestsize,
+ DATA_FMT_DIGEST, field_data);
+}
+
+/*
+ * This function writes the name of an event.
+ */
+int ima_eventname_init(struct integrity_iint_cache *iint, struct file *file,
+ const unsigned char *filename,
+ struct ima_field_data *field_data)
+{
+ const char *cur_filename = NULL;
+ u32 cur_filename_len = 0;
+
+ BUG_ON(filename == NULL && file == NULL);
+
+ if (filename) {
+ cur_filename = filename;
+ cur_filename_len = strlen(filename);
+
+ if (cur_filename_len <= IMA_EVENT_NAME_LEN_MAX)
+ goto out;
+ }
+
+ if (file) {
+ cur_filename = file->f_dentry->d_name.name;
+ cur_filename_len = strlen(cur_filename);
+ } else
+ /*
+ * Truncate filename if the latter is too long and
+ * the file descriptor is not available.
+ */
+ cur_filename_len = IMA_EVENT_NAME_LEN_MAX;
+out:
+ return ima_write_template_field_data(cur_filename, cur_filename_len,
+ DATA_FMT_EVENT_NAME, field_data);
+}