[RFC][PATCH v2 09/12] diglim: Interfaces - digest_query

Roberto Sassu
2021-07-26T16:40:46Z

Introduce the digest_query interface, which allows to write a query in the
format <algo>-<digest> and to obtain all digest lists that include that
digest.

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
security/integrity/diglim/fs.c | 154 +++++++++++++++++++++++++++++++++
1 file changed, 154 insertions(+)

diff --git a/security/integrity/diglim/fs.c b/security/integrity/diglim/fs.c
index 8958e987f708..f1c1fc56448a 100644
--- a/security/integrity/diglim/fs.c
+++ b/security/integrity/diglim/fs.c
@@ -43,6 +43,13 @@ static struct dentry *digest_lists_loaded_dir;
* list (buffer) loaded through digest_list_add.
*/
static struct dentry *digest_label_dentry;
+/**
+ * DOC: digest_query
+ *
+ * digest_query allows to write a query in the format <algo>-<digest> and
+ * to obtain all digest lists that include that digest.
+ */
+static struct dentry *digest_query_dentry;
/**
* DOC: digest_list_add
*
@@ -63,6 +70,7 @@ static struct dentry *digest_list_add_dentry;
* described for digest_list_add.
*/
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 int parse_digest_list_filename(const char *digest_list_filename,
@@ -253,6 +261,84 @@ static const struct file_operations digest_list_ascii_ops = {
.release = seq_release,
};

+/*
+ * *pos is the n-th reference to show among all the references in all digest
+ * items found with the query.
+ */
+static void *digest_query_start(struct seq_file *m, loff_t *pos)
+{
+ struct digest_item *d;
+ u8 digest[IMA_MAX_DIGEST_SIZE];
+ enum hash_algo algo;
+ loff_t count = 0;
+ enum compact_types type = 0;
+ struct digest_list_item_ref *ref;
+ int ret;
+
+ ret = parse_digest_list_filename(digest_query, digest, &algo);
+ if (ret < 0)
+ return NULL;
+
+ for (type = 0; type < COMPACT__LAST; type++) {
+ d = __digest_lookup(digest, algo, type, NULL, NULL);
+ if (!d)
+ continue;
+
+ list_for_each_entry(ref, &d->refs, list) {
+ if (count++ == *pos) {
+ m->private = d;
+ return ref;
+ }
+ }
+ }
+
+ return NULL;
+}
+
+static void *digest_query_next(struct seq_file *m, void *v, loff_t *pos)
+{
+ struct digest_item *d = (struct digest_item *)m->private;
+ struct digest_list_item_ref *cur_ref = (struct digest_list_item_ref *)v;
+ struct digest_list_item_ref *ref;
+
+ (*pos)++;
+
+ list_for_each_entry(ref, &d->refs, list) {
+ if (ref != cur_ref)
+ continue;
+
+ if (!list_is_last(&cur_ref->list, &d->refs))
+ return list_next_entry(cur_ref, list);
+ }
+
+ return NULL;
+}
+
+static void digest_query_stop(struct seq_file *m, void *v)
+{
+}
+
+static int digest_query_show(struct seq_file *m, void *v)
+{
+ struct digest_list_item_ref *ref = (struct digest_list_item_ref *)v;
+ struct digest_list_item *digest_list = ref->digest_list;
+ struct compact_list_hdr *hdr = get_hdr_ref(ref);
+
+ if (!ref->digest_offset) {
+ seq_printf(m, "%s (actions: %d): type: %d, size: %lld\n",
+ digest_list->label, digest_list->actions,
+ COMPACT_DIGEST_LIST, digest_list->size);
+ return 0;
+ }
+
+ seq_printf(m,
+ "%s (actions: %d): version: %d, algo: %s, type: %d, modifiers: %d, count: %d, datalen: %d\n",
+ digest_list->label, digest_list->actions, hdr->version,
+ hash_algo_name[hdr->algo], hdr->type, hdr->modifiers,
+ hdr->count, hdr->datalen);
+ return 0;
+}
+
static int digest_list_get_secfs_files(char *label, u8 *digest,
enum hash_algo algo, enum ops op,
struct dentry **dentry,
@@ -538,6 +624,67 @@ static const struct file_operations digest_label_ops = {
.llseek = generic_file_llseek,
};

+static const struct seq_operations digest_query_seqops = {
+ .start = digest_query_start,
+ .next = digest_query_next,
+ .stop = digest_query_stop,
+ .show = digest_query_show,
+};
+
+/*
+ * digest_query_open: sequentialize access to the add/del/query files
+ */
+static int digest_query_open(struct inode *inode, struct file *file)
+{
+ if (test_and_set_bit(0, &flags))
+ return -EBUSY;
+
+ if (file->f_flags & O_WRONLY)
+ return 0;
+
+ return seq_open(file, &digest_query_seqops);
+}
+
+/*
+ * digest_query_write: write digest query (<algo>-<digest>).
+ */
+static ssize_t digest_query_write(struct file *file, const char __user *buf,
+ size_t datalen, loff_t *ppos)
+{
+ int rc;
+
+ if (datalen >= sizeof(digest_query))
+ return -EINVAL;
+
+ rc = copy_from_user(digest_query, buf, datalen);
+ if (rc)
+ return -EFAULT;
+
+ digest_query[datalen] = '\0';
+ return datalen;
+}
+
+/*
+ * digest_query_release - release the query file
+ */
+static int digest_query_release(struct inode *inode, struct file *file)
+{
+ clear_bit(0, &flags);
+
+ if (file->f_flags & O_WRONLY)
+ return 0;
+
+ return seq_release(inode, file);
+}
+
+static const struct file_operations digest_query_ops = {
+ .open = digest_query_open,
+ .write = digest_query_write,
+ .read = seq_read,
+ .release = digest_query_release,
+ .llseek = generic_file_llseek,
+};
+
static int __init diglim_fs_init(void)
{
diglim_dir = securityfs_create_dir("diglim", integrity_dir);
@@ -567,8 +714,15 @@ static int __init diglim_fs_init(void)
if (IS_ERR(digest_label_dentry))
goto out;

+ digest_query_dentry = securityfs_create_file("digest_query", 0600,
+ diglim_dir, NULL,
+ &digest_query_ops);
+ if (IS_ERR(digest_query_dentry))
+ goto out;
+
return 0;
out:
+ securityfs_remove(digest_query_dentry);
securityfs_remove(digest_label_dentry);
securityfs_remove(digest_list_del_dentry);
securityfs_remove(digest_list_add_dentry);
--
2.25.1