Implement bpffs pretty printing for cgroup local storage maps
(both shared and per-cpu).
Output example (captured for tools/testing/selftests/bpf/netcnt_prog.c):
Shared:
$ cat /sys/fs/bpf/map_2
# WARNING!! The output is for debug purpose only
# WARNING!! The output format will change
{4294968594,1}: {9999,1039896}
Per-cpu:
$ cat /sys/fs/bpf/map_1
# WARNING!! The output is for debug purpose only
# WARNING!! The output format will change
{4294968594,1}: {
cpu0: {0,0,0,0,0}
cpu1: {0,0,0,0,0}
cpu2: {1,104,0,0,0}
cpu3: {0,0,0,0,0}
}
Signed-off-by: Roman Gushchin <g...@fb.com>
Cc: Alexei Starovoitov <a...@kernel.org>
Cc: Daniel Borkmann <dan...@iogearbox.net>
---
include/linux/btf.h | 1 +
kernel/bpf/btf.c | 22 +++++++++
kernel/bpf/local_storage.c | 93 +++++++++++++++++++++++++++++++++++++-
3 files changed, 115 insertions(+), 1 deletion(-)
diff --git a/include/linux/btf.h b/include/linux/btf.h
index b98405a56383..a4cf075b89eb 100644
--- a/include/linux/btf.h
+++ b/include/linux/btf.h
@@ -47,6 +47,7 @@ void btf_type_seq_show(const struct btf *btf, u32 type_id,
void *obj,
int btf_get_fd_by_id(u32 id);
u32 btf_id(const struct btf *btf);
bool btf_name_offset_valid(const struct btf *btf, u32 offset);
+bool btf_type_is_reg_int(const struct btf_type *t, u32 expected_size);
#ifdef CONFIG_BPF_SYSCALL
const struct btf_type *btf_type_by_id(const struct btf *btf, u32 type_id);
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index e0a827f95e19..804ab24283f6 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -514,6 +514,28 @@ static bool btf_type_int_is_regular(const struct btf_type
*t)
return true;
}
+/*
+ * Check that given type is a regular int and has the expected size.
+ */
+bool btf_type_is_reg_int(const struct btf_type *t, u32 expected_size)
+{
+ u8 nr_bits, nr_bytes;
+ u32 int_data;
+
+ if (!btf_type_is_int(t))
+ return false;
+
+ int_data = btf_type_int(t);
+ nr_bits = BTF_INT_BITS(int_data);
+ nr_bytes = BITS_ROUNDUP_BYTES(nr_bits);
+ if (BITS_PER_BYTE_MASKED(nr_bits) ||
+ BTF_INT_OFFSET(int_data) ||
+ nr_bytes != expected_size)
+ return false;
+
+ return true;
+}
+
__printf(2, 3) static void __btf_verifier_log(struct bpf_verifier_log *log,
const char *fmt, ...)
{
diff --git a/kernel/bpf/local_storage.c b/kernel/bpf/local_storage.c
index b65017dead44..5eca03da0989 100644
--- a/kernel/bpf/local_storage.c
+++ b/kernel/bpf/local_storage.c
@@ -1,11 +1,13 @@
//SPDX-License-Identifier: GPL-2.0
#include <linux/bpf-cgroup.h>
#include <linux/bpf.h>
+#include <linux/btf.h>
#include <linux/bug.h>
#include <linux/filter.h>
#include <linux/mm.h>
#include <linux/rbtree.h>
#include <linux/slab.h>
+#include <uapi/linux/btf.h>
DEFINE_PER_CPU(struct bpf_cgroup_storage*,
bpf_cgroup_storage[MAX_BPF_CGROUP_STORAGE_TYPE]);
@@ -308,6 +310,94 @@ static int cgroup_storage_delete_elem(struct bpf_map *map,
void *key)
return -EINVAL;
}
+static int cgroup_storage_check_btf(const struct bpf_map *map,
+ const struct btf *btf,
+ const struct btf_type *key_type,
+ const struct btf_type *value_type)
+{
+ const struct btf_type *t;
+ struct btf_member *m;
+ u32 id, size;
+
+ /* Key is expected to be of struct bpf_cgroup_storage_key type,
+ * which is:
+ * struct bpf_cgroup_storage_key {
+ * __u64 cgroup_inode_id;
+ * __u32 attach_type;
+ * };
+ */
+
+ /*
+ * Key_type must be a structure with two fields.
+ */
+ if (BTF_INFO_KIND(key_type->info) != BTF_KIND_STRUCT ||
+ BTF_INFO_VLEN(key_type->info) != 2)
+ return -EINVAL;
+
+ /*
+ * The first field must be a 64 bit integer at 0 offset.
+ */
+ m = (struct btf_member *)(key_type + 1);
+ if (m->offset)
+ return -EINVAL;
+ id = m->type;
+ t = btf_type_id_size(btf, &id, NULL);
+ size = FIELD_SIZEOF(struct bpf_cgroup_storage_key, cgroup_inode_id);
+ if (!t || !btf_type_is_reg_int(t, size))
+ return -EINVAL;
+
+ /*
+ * The second field must be a 32 bit integer at 64 bit offset.
+ */
+ m++;
+ if (m->offset != offsetof(struct bpf_cgroup_storage_key, attach_type) *
+ BITS_PER_BYTE)
+ return -EINVAL;
+ id = m->type;
+ t = btf_type_id_size(btf, &id, NULL);
+ size = FIELD_SIZEOF(struct bpf_cgroup_storage_key, attach_type);
+ if (!t || !btf_type_is_reg_int(t, size))
+ return -EINVAL;
+
+ return 0;
+}
+
+static void cgroup_storage_seq_show_elem(struct bpf_map *map, void *_key,
+ struct seq_file *m)
+{
+ enum bpf_cgroup_storage_type stype = cgroup_storage_type(map);
+ struct bpf_cgroup_storage_key *key = _key;
+ struct bpf_cgroup_storage *storage;
+ int cpu;
+
+ rcu_read_lock();
+ storage = cgroup_storage_lookup(map_to_storage(map), key, false);
+ if (!storage) {
+ rcu_read_unlock();
+ return;
+ }
+
+ btf_type_seq_show(map->btf, map->btf_key_type_id, key, m);
+ stype = cgroup_storage_type(map);
+ if (stype == BPF_CGROUP_STORAGE_SHARED) {
+ seq_puts(m, ": ");
+ btf_type_seq_show(map->btf, map->btf_value_type_id,
+ &READ_ONCE(storage->buf)->data[0], m);
+ seq_puts(m, "\n");
+ } else {
+ seq_puts(m, ": {\n");
+ for_each_possible_cpu(cpu) {
+ seq_printf(m, "\tcpu%d: ", cpu);
+ btf_type_seq_show(map->btf, map->btf_value_type_id,
+ per_cpu_ptr(storage->percpu_buf, cpu),
+ m);
+ seq_puts(m, "\n");
+ }
+ seq_puts(m, "}\n");
+ }
+ rcu_read_unlock();
+}
+
const struct bpf_map_ops cgroup_storage_map_ops = {
.map_alloc = cgroup_storage_map_alloc,
.map_free = cgroup_storage_map_free,
@@ -315,7 +405,8 @@ const struct bpf_map_ops cgroup_storage_map_ops = {
.map_lookup_elem = cgroup_storage_lookup_elem,
.map_update_elem = cgroup_storage_update_elem,
.map_delete_elem = cgroup_storage_delete_elem,
- .map_check_btf = map_check_no_btf,
+ .map_check_btf = cgroup_storage_check_btf,
+ .map_seq_show_elem = cgroup_storage_seq_show_elem,
};
int bpf_cgroup_storage_assign(struct bpf_prog *prog, struct bpf_map *_map)
--
2.19.2
