[PATCH bpf-next v3 04/16] bpfilter: add map container

[Quentin Deslandes <qde@naccy.de>]

Introduce common code for an associative container. This common code
will be used for maps of matches, targets, and tables. Hash search
tables from libc are used as an index.

The supported sets of operations is: create, find, upsert, free.

Co-developed-by: Dmitrii Banshchikov <me@ubique.spb.ru>
Signed-off-by: Dmitrii Banshchikov <me@ubique.spb.ru>
Signed-off-by: Quentin Deslandes <qde@naccy.de>
---
 net/bpfilter/Makefile                         |  2 +-
 net/bpfilter/map-common.c                     | 51 +++++++++++++++
 net/bpfilter/map-common.h                     | 19 ++++++
 .../testing/selftests/bpf/bpfilter/.gitignore |  2 +
 tools/testing/selftests/bpf/bpfilter/Makefile | 19 ++++++
 .../testing/selftests/bpf/bpfilter/test_map.c | 63 +++++++++++++++++++
 6 files changed, 155 insertions(+), 1 deletion(-)
 create mode 100644 net/bpfilter/map-common.c
 create mode 100644 net/bpfilter/map-common.h
 create mode 100644 tools/testing/selftests/bpf/bpfilter/.gitignore
 create mode 100644 tools/testing/selftests/bpf/bpfilter/Makefile
 create mode 100644 tools/testing/selftests/bpf/bpfilter/test_map.c

diff --git a/net/bpfilter/Makefile b/net/bpfilter/Makefile
index 8d9c726ba1a5..1b0c399c19df 100644
--- a/net/bpfilter/Makefile
+++ b/net/bpfilter/Makefile
@@ -4,7 +4,7 @@
 #
 
 userprogs := bpfilter_umh
-bpfilter_umh-objs := main.o logger.o
+bpfilter_umh-objs := main.o logger.o map-common.o
 userccflags += -I $(srctree)/tools/include/ -I $(srctree)/tools/include/uapi
 
 ifeq ($(CONFIG_BPFILTER_UMH), y)
diff --git a/net/bpfilter/map-common.c b/net/bpfilter/map-common.c
new file mode 100644
index 000000000000..cc6c3a59b315
--- /dev/null
+++ b/net/bpfilter/map-common.c
@@ -0,0 +1,51 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2021 Telegram FZ-LLC
+ * Copyright (c) 2022 Meta Platforms, Inc. and affiliates.
+ */
+
+#include "map-common.h"
+
+#include <linux/err.h>
+
+#include <errno.h>
+#include <string.h>
+
+int create_map(struct hsearch_data *htab, size_t nelem)
+{
+	memset(htab, 0, sizeof(*htab));
+	if (!hcreate_r(nelem, htab))
+		return -errno;
+
+	return 0;
+}
+
+void *map_find(struct hsearch_data *htab, const char *key)
+{
+	const ENTRY needle = { .key = (char *)key };
+	ENTRY *found;
+
+	if (!hsearch_r(needle, FIND, &found, htab))
+		return ERR_PTR(-ENOENT);
+
+	return found->data;
+}
+
+int map_upsert(struct hsearch_data *htab, const char *key, void *value)
+{
+	const ENTRY needle = { .key = (char *)key, .data = value };
+	ENTRY *found;
+
+	if (!hsearch_r(needle, ENTER, &found, htab))
+		return -errno;
+
+	found->key = (char *)key;
+	found->data = value;
+
+	return 0;
+}
+
+void free_map(struct hsearch_data *htab)
+{
+	hdestroy_r(htab);
+}
diff --git a/net/bpfilter/map-common.h b/net/bpfilter/map-common.h
new file mode 100644
index 000000000000..666a4ffe9b29
--- /dev/null
+++ b/net/bpfilter/map-common.h
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2021 Telegram FZ-LLC
+ * Copyright (c) 2022 Meta Platforms, Inc. and affiliates.
+ */
+
+#ifndef NET_BPFILTER_MAP_COMMON_H
+#define NET_BPFILTER_MAP_COMMON_H
+
+#define _GNU_SOURCE
+
+#include <search.h>
+
+int create_map(struct hsearch_data *htab, size_t nelem);
+void *map_find(struct hsearch_data *htab, const char *key);
+int map_upsert(struct hsearch_data *htab, const char *key, void *value);
+void free_map(struct hsearch_data *htab);
+
+#endif // NET_BPFILTER_MAP_COMMON_H
diff --git a/tools/testing/selftests/bpf/bpfilter/.gitignore b/tools/testing/selftests/bpf/bpfilter/.gitignore
new file mode 100644
index 000000000000..983fd06cbefa
--- /dev/null
+++ b/tools/testing/selftests/bpf/bpfilter/.gitignore
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+test_map
diff --git a/tools/testing/selftests/bpf/bpfilter/Makefile b/tools/testing/selftests/bpf/bpfilter/Makefile
new file mode 100644
index 000000000000..c262aad8c2a4
--- /dev/null
+++ b/tools/testing/selftests/bpf/bpfilter/Makefile
@@ -0,0 +1,19 @@
+# SPDX-License-Identifier: GPL-2.0
+
+top_srcdir = ../../../../..
+TOOLSDIR := $(abspath ../../../../)
+TOOLSINCDIR := $(TOOLSDIR)/include
+APIDIR := $(TOOLSINCDIR)/uapi
+BPFILTERSRCDIR := $(top_srcdir)/net/bpfilter
+
+CFLAGS += -Wall -g -pthread -I$(TOOLSINCDIR) -I$(APIDIR) -I$(BPFILTERSRCDIR)
+
+TEST_GEN_PROGS += test_map
+
+KSFT_KHDR_INSTALL := 1
+
+include ../../lib.mk
+
+BPFILTER_MAP_SRCS := $(BPFILTERSRCDIR)/map-common.c
+
+$(OUTPUT)/test_map: test_map.c $(BPFILTER_MAP_SRCS)
diff --git a/tools/testing/selftests/bpf/bpfilter/test_map.c b/tools/testing/selftests/bpf/bpfilter/test_map.c
new file mode 100644
index 000000000000..7ed737b78816
--- /dev/null
+++ b/tools/testing/selftests/bpf/bpfilter/test_map.c
@@ -0,0 +1,63 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "map-common.h"
+
+#include <linux/err.h>
+
+#include "../../kselftest_harness.h"
+
+FIXTURE(test_map)
+{
+	struct hsearch_data map;
+	const char *key;
+	void *expected;
+	void *actual;
+};
+
+FIXTURE_SETUP(test_map)
+{
+	const int max_nelements = 100;
+
+	create_map(&self->map, max_nelements);
+	self->key = "key";
+	self->expected = "expected";
+	self->actual = "actual";
+}
+
+FIXTURE_TEARDOWN(test_map)
+{
+	free_map(&self->map);
+}
+
+TEST_F(test_map, upsert_and_find)
+{
+	void *found;
+
+	found = map_find(&self->map, self->key);
+	ASSERT_TRUE(IS_ERR(found))
+	ASSERT_EQ(-ENOENT, PTR_ERR(found))
+
+	ASSERT_EQ(0, map_upsert(&self->map, self->key, self->expected));
+	ASSERT_EQ(0, map_upsert(&self->map, self->key, self->expected));
+	ASSERT_EQ(0, map_upsert(&self->map, self->key, self->actual));
+
+	found = map_find(&self->map, self->key);
+
+	ASSERT_FALSE(IS_ERR(found));
+	ASSERT_STREQ(self->actual, found);
+}
+
+TEST_F(test_map, update)
+{
+	void *found;
+
+	ASSERT_EQ(0, map_upsert(&self->map, self->key, self->actual));
+	ASSERT_EQ(0, map_upsert(&self->map, self->key, self->expected));
+
+	found = map_find(&self->map, self->key);
+
+	ASSERT_FALSE(IS_ERR(found));
+	ASSERT_STREQ(self->expected, found);
+}
+
+TEST_HARNESS_MAIN
-- 
2.38.1