[RFC][PATCH v2 10/12] diglim: Interfaces - digests_count

[Roberto Sassu <roberto.sassu@xxxxxxxxxx>]

Introduce the digests_count interface, which shows the current number of
digests stored in the hash table by type.

Reported-by: kernel test robot <lkp@xxxxxxxxx> (frame size warning)
Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
---
 security/integrity/diglim/fs.c | 48 ++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)

diff --git a/security/integrity/diglim/fs.c b/security/integrity/diglim/fs.c
index f1c1fc56448a..3b1d9616cb62 100644
--- a/security/integrity/diglim/fs.c
+++ b/security/integrity/diglim/fs.c
@@ -23,6 +23,7 @@
 #include "diglim.h"
 
 #define MAX_DIGEST_LIST_SIZE (64 * 1024 * 1024 - 1)
+#define TMPBUF_SIZE 512
 
 static struct dentry *diglim_dir;
 /**
@@ -36,6 +37,13 @@ static struct dentry *diglim_dir;
  * removed.
  */
 static struct dentry *digest_lists_loaded_dir;
+/**
+ * DOC: digests_count
+ *
+ * digests_count shows the current number of digests stored in the hash
+ * table by type.
+ */
+static struct dentry *digests_count;
 /**
  * DOC: digest_label
  *
@@ -73,6 +81,39 @@ static struct dentry *digest_list_del_dentry;
 char digest_query[CRYPTO_MAX_ALG_NAME + 1 + IMA_MAX_DIGEST_SIZE * 2 + 1];
 char digest_label[NAME_MAX + 1];
 
+static char *types_str[COMPACT__LAST] = {
+	[COMPACT_PARSER] = "Parser",
+	[COMPACT_FILE] = "File",
+	[COMPACT_METADATA] = "Metadata",
+	[COMPACT_DIGEST_LIST] = "Digest list",
+};
+
+static ssize_t diglim_show_htable_len(struct file *filp, char __user *buf,
+				      size_t count, loff_t *ppos)
+{
+	char *tmpbuf;
+	ssize_t ret, len = 0;
+	int i;
+
+	tmpbuf = kmalloc(TMPBUF_SIZE, GFP_KERNEL);
+	if (!tmpbuf)
+		return -ENOMEM;
+
+	for (i = COMPACT_PARSER; i < COMPACT__LAST; i++)
+		len += scnprintf(tmpbuf + len, TMPBUF_SIZE - len,
+				 "%s digests: %lu\n", types_str[i],
+				 htable[i].len);
+
+	ret = simple_read_from_buffer(buf, count, ppos, tmpbuf, len);
+	kfree(tmpbuf);
+	return ret;
+}
+
+static const struct file_operations htable_len_ops = {
+	.read = diglim_show_htable_len,
+	.llseek = generic_file_llseek,
+};
+
 static int parse_digest_list_filename(const char *digest_list_filename,
 				      u8 *digest, enum hash_algo *algo)
 {
@@ -696,6 +737,12 @@ static int __init diglim_fs_init(void)
 	if (IS_ERR(digest_lists_loaded_dir))
 		goto out;
 
+	digests_count = securityfs_create_file("digests_count", 0440,
+					       diglim_dir, NULL,
+					       &htable_len_ops);
+	if (IS_ERR(digests_count))
+		goto out;
+
 	digest_list_add_dentry = securityfs_create_file("digest_list_add", 0200,
 						diglim_dir, NULL,
 						&digest_list_upload_ops);
@@ -726,6 +773,7 @@ static int __init diglim_fs_init(void)
 	securityfs_remove(digest_label_dentry);
 	securityfs_remove(digest_list_del_dentry);
 	securityfs_remove(digest_list_add_dentry);
+	securityfs_remove(digests_count);
 	securityfs_remove(digest_lists_loaded_dir);
 	securityfs_remove(diglim_dir);
 	return -1;
-- 
2.25.1