apparmor: support querying extended trusted helper extra data

Allow a profile to carry extra data that can be queried via userspace.
This provides a means to store extra data in a profile that a trusted
helper can extract and use from live policy.

Signed-off-by: William Hua <william.hua@canonical.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>

security/apparmor/policy_unpack.c

@@ -485,6 +485,30 @@ fail:
 	return 0;
 }
 
+static void *kvmemdup(const void *src, size_t len)
+{
+	void *p = kvmalloc(len);
+
+	if (p)
+		memcpy(p, src, len);
+	return p;
+}
+
+static u32 strhash(const void *data, u32 len, u32 seed)
+{
+	const char * const *key = data;
+
+	return jhash(*key, strlen(*key), seed);
+}
+
+static int datacmp(struct rhashtable_compare_arg *arg, const void *obj)
+{
+	const struct aa_data *data = obj;
+	const char * const *key = arg->key;
+
+	return strcmp(data->key, *key);
+}
+
 /**
  * unpack_profile - unpack a serialized profile
  * @e: serialized data extent information (NOT NULL)
@@ -496,6 +520,9 @@ static struct aa_profile *unpack_profile(struct aa_ext *e, char **ns_name)
 	struct aa_profile *profile = NULL;
 	const char *tmpname, *tmpns = NULL, *name = NULL;
 	size_t ns_len;
+	struct rhashtable_params params = { 0 };
+	char *key = NULL;
+	struct aa_data *data;
 	int i, error = -EPROTO;
 	kernel_cap_t tmpcap;
 	u32 tmp;
@@ -654,6 +681,45 @@ static struct aa_profile *unpack_profile(struct aa_ext *e, char **ns_name)
 	if (!unpack_trans_table(e, profile))
 		goto fail;
 
+	if (unpack_nameX(e, AA_STRUCT, "data")) {
+		profile->data = kzalloc(sizeof(*profile->data), GFP_KERNEL);
+		if (!profile->data)
+			goto fail;
+
+		params.nelem_hint = 3;
+		params.key_len = sizeof(void *);
+		params.key_offset = offsetof(struct aa_data, key);
+		params.head_offset = offsetof(struct aa_data, head);
+		params.hashfn = strhash;
+		params.obj_cmpfn = datacmp;
+
+		if (rhashtable_init(profile->data, &params))
+			goto fail;
+
+		while (unpack_strdup(e, &key, NULL)) {
+			data = kzalloc(sizeof(*data), GFP_KERNEL);
+			if (!data) {
+				kzfree(key);
+				goto fail;
+			}
+
+			data->key = key;
+			data->size = unpack_blob(e, &data->data, NULL);
+			data->data = kvmemdup(data->data, data->size);
+			if (data->size && !data->data) {
+				kzfree(data->key);
+				kzfree(data);
+				goto fail;
+			}
+
+			rhashtable_insert_fast(profile->data, &data->head,
+					       profile->data->p);
+		}
+
+		if (!unpack_nameX(e, AA_STRUCTEND, NULL))
+			goto fail;
+	}
+
 	if (!unpack_nameX(e, AA_STRUCTEND, NULL))
 		goto fail;