[v3 PATCH bpf-next 0/2] bpf: Add percpu map value size check

[v3 PATCH bpf-next 0/2] bpf: Add percpu map value size check

[Tao Chen]

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

Tao Chen (2):
  bpf: Check percpu map value size first
  bpf/selftests: Check errno when percpu map value size exceeds

 kernel/bpf/arraymap.c                          |  3 +++
 kernel/bpf/hashtab.c                           |  3 +++
 .../selftests/bpf/map_tests/map_percpu_stats.c | 18 ++++++++++++++++++
 3 files changed, 24 insertions(+)

-- 
2.43.0

[v3 PATCH bpf-next 1/2] bpf: Check percpu map value size first

[Tao Chen]

Percpu map is often used, but the map value size limit often ignored,
like issue: https://github.com/iovisor/bcc/issues/2519. Actually,
percpu map value size is bound by PCPU_MIN_UNIT_SIZE, so we
can check the value size whether it exceeds PCPU_MIN_UNIT_SIZE first,
like percpu map of local_storage. Maybe the error message seems clearer
compared with "cannot allocate memory".

Signed-off-by: Tao Chen <chen.dylane@gmail.com>
Signed-off-by: Jinke Han <jinkehan@didiglobal.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
---
 kernel/bpf/arraymap.c | 3 +++
 kernel/bpf/hashtab.c  | 3 +++
 2 files changed, 6 insertions(+)

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;
 }
-- 
2.43.0

[v3 PATCH bpf-next 2/2] bpf/selftests: Check errno when percpu map value size exceeds

[Tao Chen]

This test case checks the errno message when percpu map value size
exceeds PCPU_MIN_UNIT_SIZE.

root@debian:~# ./test_maps
...
test_map_percpu_stats_hash_of_maps:PASS
test_map_percpu_stats_map_value_size:PASS
test_sk_storage_map:PASS

Signed-off-by: Tao Chen <chen.dylane@gmail.com>
Signed-off-by: Jinke Han <jinkehan@didiglobal.com>
---
 .../selftests/bpf/map_tests/map_percpu_stats.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

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();
 }
-- 
2.43.0

Re: [v3 PATCH bpf-next 0/2] bpf: Add percpu map value size check

[patchwork-bot+netdevbpf]

Hello:

This series was applied to bpf/bpf-next.git (master)
by Andrii Nakryiko <andrii@kernel.org>:

On Tue, 10 Sep 2024 22:41:09 +0800 you wrote:
> 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
> 
> [...]

Here is the summary with links:
  - [v3,bpf-next,1/2] bpf: Check percpu map value size first
    https://git.kernel.org/bpf/bpf-next/c/1d244784be6b
  - [v3,bpf-next,2/2] bpf/selftests: Check errno when percpu map value size exceeds
    https://git.kernel.org/bpf/bpf-next/c/7eab3a58ac7b

You are awesome, thank you!
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