Merge branch 'bpf-add-percpu-map-value-size-check'

Tao Chen says:

====================
bpf: Add percpu map value size check

Check percpu map value size first and add the test case in selftest.

Change list:
- v2 -> v3:
    - use bpf_map_create API and mv test case in map_percpu_stats.c
- v1 -> v2:
    - round up map value size with 8 bytes in patch 1
    - add selftest case in patch 2
====================

Link: https://lore.kernel.org/r/20240910144111.1464912-1-chen.dylane@gmail.com
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>

3 files changed, 24 insertions, 0 deletions

diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index a43e62e2a8bb..79660e3fca4c 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -73,6 +73,9 @@ int array_map_alloc_check(union bpf_attr *attr)
 	/* avoid overflow on round_up(map->value_size) */
 	if (attr->value_size > INT_MAX)
 		return -E2BIG;
+	/* percpu map value size is bound by PCPU_MIN_UNIT_SIZE */
+	if (percpu && round_up(attr->value_size, 8) > PCPU_MIN_UNIT_SIZE)
+		return -E2BIG;
 
 	return 0;
 }
diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
index 45c7195b65ba..b14b87463ee0 100644
--- a/kernel/bpf/hashtab.c
+++ b/kernel/bpf/hashtab.c
@@ -462,6 +462,9 @@ static int htab_map_alloc_check(union bpf_attr *attr)
 		 * kmalloc-able later in htab_map_update_elem()
 		 */
 		return -E2BIG;
+	/* percpu map value size is bound by PCPU_MIN_UNIT_SIZE */
+	if (percpu && round_up(attr->value_size, 8) > PCPU_MIN_UNIT_SIZE)
+		return -E2BIG;
 
 	return 0;
 }
diff --git a/tools/testing/selftests/bpf/map_tests/map_percpu_stats.c b/tools/testing/selftests/bpf/map_tests/map_percpu_stats.c
index 2ea36408816b..1c7c04288eff 100644
--- a/tools/testing/selftests/bpf/map_tests/map_percpu_stats.c
+++ b/tools/testing/selftests/bpf/map_tests/map_percpu_stats.c
@@ -17,6 +17,7 @@
 #define MAX_ENTRIES_HASH_OF_MAPS	64
 #define N_THREADS			8
 #define MAX_MAP_KEY_SIZE		4
+#define PCPU_MIN_UNIT_SIZE		32768
 
 static void map_info(int map_fd, struct bpf_map_info *info)
 {
@@ -456,6 +457,22 @@ static void map_percpu_stats_hash_of_maps(void)
 	printf("test_%s:PASS\n", __func__);
 }
 
+static void map_percpu_stats_map_value_size(void)
+{
+	int fd;
+	int value_sz = PCPU_MIN_UNIT_SIZE + 1;
+	struct bpf_map_create_opts opts = { .sz = sizeof(opts) };
+	enum bpf_map_type map_types[] = { BPF_MAP_TYPE_PERCPU_ARRAY,
+					  BPF_MAP_TYPE_PERCPU_HASH,
+					  BPF_MAP_TYPE_LRU_PERCPU_HASH };
+	for (int i = 0; i < ARRAY_SIZE(map_types); i++) {
+		fd = bpf_map_create(map_types[i], NULL, sizeof(__u32), value_sz, 1, &opts);
+		CHECK(fd < 0 && errno != E2BIG, "percpu map value size",
+			"error: %s\n", strerror(errno));
+	}
+	printf("test_%s:PASS\n", __func__);
+}
+
 void test_map_percpu_stats(void)
 {
 	map_percpu_stats_hash();
@@ -467,4 +484,5 @@ void test_map_percpu_stats(void)
 	map_percpu_stats_percpu_lru_hash();
 	map_percpu_stats_percpu_lru_hash_no_common();
 	map_percpu_stats_hash_of_maps();
+	map_percpu_stats_map_value_size();
 }