[PATCH bpf-next v11 03/13] bpf, net: introduce bpf_struct_ops_desc.

thinker.li
2023-11-06T20:13:08Z

From: Kui-Feng Lee <thinker.li@gmail.com>

Move some of members of bpf_struct_ops to bpf_struct_ops_desc. When we
introduce the new API to register new bpf_struct_ops types from modules,
bpf_struct_ops may destroyed when the module is unloaded. Moving these
members to bpf_struct_ops_desc make these data available even when the
module is unloaded.

type_id is unavailabe in bpf_struct_ops anymore. Modules should get it from
the btf received by kmod's init function.

Cc: netdev@vger.kernel.org
Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
---
include/linux/bpf.h | 13 ++++--
kernel/bpf/bpf_struct_ops.c | 80 +++++++++++++++++-----------------
kernel/bpf/verifier.c | 8 ++--
net/bpf/bpf_dummy_struct_ops.c | 9 +++-
net/ipv4/bpf_tcp_ca.c | 8 +++-
5 files changed, 70 insertions(+), 48 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index b4825d3cdb29..b55e27162df0 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1626,17 +1626,22 @@ struct bpf_struct_ops {
void (*unreg)(void *kdata);
int (*update)(void *kdata, void *old_kdata);
int (*validate)(void *kdata);
- const struct btf_type *type;
- const struct btf_type *value_type;
const char *name;
struct btf_func_model func_models[BPF_STRUCT_OPS_MAX_NR_MEMBERS];
+};
+
+struct bpf_struct_ops_desc {
+ struct bpf_struct_ops *st_ops;
+
+ const struct btf_type *type;
+ const struct btf_type *value_type;
u32 type_id;
u32 value_id;
};

#if defined(CONFIG_BPF_JIT) && defined(CONFIG_BPF_SYSCALL)
#define BPF_MODULE_OWNER ((void *)((0xeB9FUL << 2) + POISON_POINTER_DELTA))
-const struct bpf_struct_ops *bpf_struct_ops_find(u32 type_id);
+const struct bpf_struct_ops_desc *bpf_struct_ops_find(u32 type_id);
void bpf_struct_ops_init(struct btf *btf, struct bpf_verifier_log *log);
bool bpf_struct_ops_get(const void *kdata);
void bpf_struct_ops_put(const void *kdata);
@@ -1679,7 +1684,7 @@ int bpf_struct_ops_test_run(struct bpf_prog *prog, const union bpf_attr *kattr,
union bpf_attr __user *uattr);
#endif
#else
-static inline const struct bpf_struct_ops *bpf_struct_ops_find(u32 type_id)
+static inline const struct bpf_struct_ops_desc *bpf_struct_ops_find(u32 type_id)
{
return NULL;
}
diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c
index 4ca4ca4998e0..d804801c7864 100644
--- a/kernel/bpf/bpf_struct_ops.c
+++ b/kernel/bpf/bpf_struct_ops.c
@@ -32,7 +32,7 @@ struct bpf_struct_ops_value {
struct bpf_struct_ops_map {
struct bpf_map map;
struct rcu_head rcu;
- const struct bpf_struct_ops *st_ops;
+ const struct bpf_struct_ops_desc *st_ops_desc;
/* protect map_update */
struct mutex lock;
/* link has all the bpf_links that is populated
@@ -92,9 +92,9 @@ enum {
__NR_BPF_STRUCT_OPS_TYPE,
};

-static struct bpf_struct_ops * const bpf_struct_ops[] = {
+static struct bpf_struct_ops_desc bpf_struct_ops[] = {
#define BPF_STRUCT_OPS_TYPE(_name) \
- [BPF_STRUCT_OPS_TYPE_##_name] = &bpf_##_name,
+ [BPF_STRUCT_OPS_TYPE_##_name] = { .st_ops = &bpf_##_name },
#include "bpf_struct_ops_types.h"
#undef BPF_STRUCT_OPS_TYPE
};
@@ -115,10 +115,11 @@ enum {
IDX_MODULE_ID,
};

-static void bpf_struct_ops_init_one(struct bpf_struct_ops *st_ops,
- struct btf *btf,
- struct bpf_verifier_log *log)
+static void bpf_struct_ops_desc_init(struct bpf_struct_ops_desc *st_ops_desc,
+ struct btf *btf,
+ struct bpf_verifier_log *log)
{
+ struct bpf_struct_ops *st_ops = st_ops_desc->st_ops;
const struct btf_member *member;
const struct btf_type *t;
s32 type_id, value_id;
@@ -190,18 +191,18 @@ static void bpf_struct_ops_init_one(struct bpf_struct_ops *st_ops,
pr_warn("Error in init bpf_struct_ops %s\n",
st_ops->name);
} else {
- st_ops->type_id = type_id;
- st_ops->type = t;
- st_ops->value_id = value_id;
- st_ops->value_type = btf_type_by_id(btf,
- value_id);
+ st_ops_desc->type_id = type_id;
+ st_ops_desc->type = t;
+ st_ops_desc->value_id = value_id;
+ st_ops_desc->value_type = btf_type_by_id(btf,
+ value_id);
}
}
}

void bpf_struct_ops_init(struct btf *btf, struct bpf_verifier_log *log)
{
- struct bpf_struct_ops *st_ops;
+ struct bpf_struct_ops_desc *st_ops_desc;
u32 i;

/* Ensure BTF type is emitted for "struct bpf_struct_ops_##_name" */
@@ -210,14 +211,14 @@ void bpf_struct_ops_init(struct btf *btf, struct bpf_verifier_log *log)
#undef BPF_STRUCT_OPS_TYPE

for (i = 0; i < ARRAY_SIZE(bpf_struct_ops); i++) {
- st_ops = bpf_struct_ops[i];
- bpf_struct_ops_init_one(st_ops, btf, log);
+ st_ops_desc = &bpf_struct_ops[i];
+ bpf_struct_ops_desc_init(st_ops_desc, btf, log);
}
}

extern struct btf *btf_vmlinux;

-static const struct bpf_struct_ops *
+static const struct bpf_struct_ops_desc *
bpf_struct_ops_find_value(u32 value_id)
{
unsigned int i;
@@ -226,14 +227,14 @@ bpf_struct_ops_find_value(u32 value_id)
return NULL;

for (i = 0; i < ARRAY_SIZE(bpf_struct_ops); i++) {
- if (bpf_struct_ops[i]->value_id == value_id)
- return bpf_struct_ops[i];
+ if (bpf_struct_ops[i].value_id == value_id)
+ return &bpf_struct_ops[i];
}

return NULL;
}

-const struct bpf_struct_ops *bpf_struct_ops_find(u32 type_id)
+const struct bpf_struct_ops_desc *bpf_struct_ops_find(u32 type_id)
{
unsigned int i;

@@ -241,8 +242,8 @@ const struct bpf_struct_ops *bpf_struct_ops_find(u32 type_id)
return NULL;

for (i = 0; i < ARRAY_SIZE(bpf_struct_ops); i++) {
- if (bpf_struct_ops[i]->type_id == type_id)
- return bpf_struct_ops[i];
+ if (bpf_struct_ops[i].type_id == type_id)
+ return &bpf_struct_ops[i];
}

return NULL;
@@ -302,7 +303,7 @@ static void *bpf_struct_ops_map_lookup_elem(struct bpf_map *map, void *key)

static void bpf_struct_ops_map_put_progs(struct bpf_struct_ops_map *st_map)
{
- const struct btf_type *t = st_map->st_ops->type;
+ const struct btf_type *t = st_map->st_ops_desc->type;
u32 i;

for (i = 0; i < btf_type_vlen(t); i++) {
@@ -376,11 +377,12 @@ static long bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key,
void *value, u64 flags)
{
struct bpf_struct_ops_map *st_map = (struct bpf_struct_ops_map *)map;
- const struct bpf_struct_ops *st_ops = st_map->st_ops;
+ const struct bpf_struct_ops_desc *st_ops_desc = st_map->st_ops_desc;
+ const struct bpf_struct_ops *st_ops = st_ops_desc->st_ops;
struct bpf_struct_ops_value *uvalue, *kvalue;
const struct btf_type *module_type;
const struct btf_member *member;
- const struct btf_type *t = st_ops->type;
+ const struct btf_type *t = st_ops_desc->type;
struct bpf_tramp_links *tlinks;
void *udata, *kdata;
int prog_fd, err;
@@ -393,7 +395,7 @@ static long bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key,
if (*(u32 *)key != 0)
return -E2BIG;

- err = check_zero_holes(st_ops->value_type, value);
+ err = check_zero_holes(st_ops_desc->value_type, value);
if (err)
return err;

@@ -486,7 +488,7 @@ static long bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key,
}

if (prog->type != BPF_PROG_TYPE_STRUCT_OPS ||
- prog->aux->attach_btf_id != st_ops->type_id ||
+ prog->aux->attach_btf_id != st_ops_desc->type_id ||
prog->expected_attach_type != i) {
bpf_prog_put(prog);
err = -EINVAL;
@@ -582,7 +584,7 @@ static long bpf_struct_ops_map_delete_elem(struct bpf_map *map, void *key)
BPF_STRUCT_OPS_STATE_TOBEFREE);
switch (prev_state) {
case BPF_STRUCT_OPS_STATE_INUSE:
- st_map->st_ops->unreg(&st_map->kvalue.data);
+ st_map->st_ops_desc->st_ops->unreg(&st_map->kvalue.data);
bpf_map_put(map);
return 0;
case BPF_STRUCT_OPS_STATE_TOBEFREE:
@@ -663,22 +665,22 @@ static int bpf_struct_ops_map_alloc_check(union bpf_attr *attr)

static struct bpf_map *bpf_struct_ops_map_alloc(union bpf_attr *attr)
{
- const struct bpf_struct_ops *st_ops;
+ const struct bpf_struct_ops_desc *st_ops_desc;
size_t st_map_size;
struct bpf_struct_ops_map *st_map;
const struct btf_type *t, *vt;
struct bpf_map *map;
int ret;

- st_ops = bpf_struct_ops_find_value(attr->btf_vmlinux_value_type_id);
- if (!st_ops)
+ st_ops_desc = bpf_struct_ops_find_value(attr->btf_vmlinux_value_type_id);
+ if (!st_ops_desc)
return ERR_PTR(-ENOTSUPP);

- vt = st_ops->value_type;
+ vt = st_ops_desc->value_type;
if (attr->value_size != vt->size)
return ERR_PTR(-EINVAL);

- t = st_ops->type;
+ t = st_ops_desc->type;

st_map_size = sizeof(*st_map) +
/* kvalue stores the
@@ -690,7 +692,7 @@ static struct bpf_map *bpf_struct_ops_map_alloc(union bpf_attr *attr)
if (!st_map)
return ERR_PTR(-ENOMEM);

- st_map->st_ops = st_ops;
+ st_map->st_ops_desc = st_ops_desc;
map = &st_map->map;

ret = bpf_jit_charge_modmem(PAGE_SIZE);
@@ -728,8 +730,8 @@ static struct bpf_map *bpf_struct_ops_map_alloc(union bpf_attr *attr)
static u64 bpf_struct_ops_map_mem_usage(const struct bpf_map *map)
{
struct bpf_struct_ops_map *st_map = (struct bpf_struct_ops_map *)map;
- const struct bpf_struct_ops *st_ops = st_map->st_ops;
- const struct btf_type *vt = st_ops->value_type;
+ const struct bpf_struct_ops_desc *st_ops_desc = st_map->st_ops_desc;
+ const struct btf_type *vt = st_ops_desc->value_type;
u64 usage;

usage = sizeof(*st_map) +
@@ -803,7 +805,7 @@ static void bpf_struct_ops_map_link_dealloc(struct bpf_link *link)
/* st_link->map can be NULL if
* bpf_struct_ops_link_create() fails to register.
*/
- st_map->st_ops->unreg(&st_map->kvalue.data);
+ st_map->st_ops_desc->st_ops->unreg(&st_map->kvalue.data);
bpf_map_put(&st_map->map);
}
kfree(st_link);
@@ -850,7 +852,7 @@ static int bpf_struct_ops_map_link_update(struct bpf_link *link, struct bpf_map
if (!bpf_struct_ops_valid_to_reg(new_map))
return -EINVAL;

- if (!st_map->st_ops->update)
+ if (!st_map->st_ops_desc->st_ops->update)
return -EOPNOTSUPP;

mutex_lock(&update_mutex);
@@ -863,12 +865,12 @@ static int bpf_struct_ops_map_link_update(struct bpf_link *link, struct bpf_map

old_st_map = container_of(old_map, struct bpf_struct_ops_map, map);
/* The new and old struct_ops must be the same type. */
- if (st_map->st_ops != old_st_map->st_ops) {
+ if (st_map->st_ops_desc != old_st_map->st_ops_desc) {
err = -EINVAL;
goto err_out;
}

- err = st_map->st_ops->update(st_map->kvalue.data, old_st_map->kvalue.data);
+ err = st_map->st_ops_desc->st_ops->update(st_map->kvalue.data, old_st_map->kvalue.data);
if (err)
goto err_out;

@@ -919,7 +921,7 @@ int bpf_struct_ops_link_create(union bpf_attr *attr)
if (err)
goto err_out;

- err = st_map->st_ops->reg(st_map->kvalue.data);
+ err = st_map->st_ops_desc->st_ops->reg(st_map->kvalue.data);
if (err) {
bpf_link_cleanup(&link_primer);
link = NULL;
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 857d76694517..290e3a7ee72f 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -20081,6 +20081,7 @@ static void print_verification_stats(struct bpf_verifier_env *env)
static int check_struct_ops_btf_id(struct bpf_verifier_env *env)
{
const struct btf_type *t, *func_proto;
+ const struct bpf_struct_ops_desc *st_ops_desc;
const struct bpf_struct_ops *st_ops;
const struct btf_member *member;
struct bpf_prog *prog = env->prog;
@@ -20093,14 +20094,15 @@ static int check_struct_ops_btf_id(struct bpf_verifier_env *env)
}

btf_id = prog->aux->attach_btf_id;
- st_ops = bpf_struct_ops_find(btf_id);
- if (!st_ops) {
+ st_ops_desc = bpf_struct_ops_find(btf_id);
+ if (!st_ops_desc) {
verbose(env, "attach_btf_id %u is not a supported struct\n",
btf_id);
return -ENOTSUPP;
}
+ st_ops = st_ops_desc->st_ops;

- t = st_ops->type;
+ t = st_ops_desc->type;
member_idx = prog->expected_attach_type;
if (member_idx >= btf_type_vlen(t)) {
verbose(env, "attach to invalid member idx %u of struct %s\n",
diff --git a/net/bpf/bpf_dummy_struct_ops.c b/net/bpf/bpf_dummy_struct_ops.c
index 5918d1b32e19..ffa224053a6c 100644
--- a/net/bpf/bpf_dummy_struct_ops.c
+++ b/net/bpf/bpf_dummy_struct_ops.c
@@ -17,6 +17,8 @@ struct bpf_dummy_ops_test_args {
struct bpf_dummy_ops_state state;
};

+static struct btf *bpf_dummy_ops_btf;
+
static struct bpf_dummy_ops_test_args *
dummy_ops_init_args(const union bpf_attr *kattr, unsigned int nr)
{
@@ -85,9 +87,13 @@ int bpf_struct_ops_test_run(struct bpf_prog *prog, const union bpf_attr *kattr,
void *image = NULL;
unsigned int op_idx;
int prog_ret;
+ u32 type_id;
int err;

- if (prog->aux->attach_btf_id != st_ops->type_id)
+ type_id = btf_find_by_name_kind(bpf_dummy_ops_btf,
+ bpf_bpf_dummy_ops.name,
+ BTF_KIND_STRUCT);
+ if (prog->aux->attach_btf_id != type_id)
return -EOPNOTSUPP;

func_proto = prog->aux->attach_func_proto;
@@ -143,6 +149,7 @@ int bpf_struct_ops_test_run(struct bpf_prog *prog, const union bpf_attr *kattr,

static int bpf_dummy_init(struct btf *btf)
{
+ bpf_dummy_ops_btf = btf;
return 0;
}

diff --git a/net/ipv4/bpf_tcp_ca.c b/net/ipv4/bpf_tcp_ca.c
index 39dcccf0f174..3c8b76578a2a 100644
--- a/net/ipv4/bpf_tcp_ca.c
+++ b/net/ipv4/bpf_tcp_ca.c
@@ -20,6 +20,7 @@ static u32 unsupported_ops[] = {

static const struct btf_type *tcp_sock_type;
static u32 tcp_sock_id, sock_id;
+static const struct btf_type *tcp_congestion_ops_type;

static int bpf_tcp_ca_init(struct btf *btf)
{
@@ -36,6 +37,11 @@ static int bpf_tcp_ca_init(struct btf *btf)
tcp_sock_id = type_id;
tcp_sock_type = btf_type_by_id(btf, tcp_sock_id);

+ type_id = btf_find_by_name_kind(btf, "tcp_congestion_ops", BTF_KIND_STRUCT);
+ if (type_id < 0)
+ return -EINVAL;
+ tcp_congestion_ops_type = btf_type_by_id(btf, type_id);
+
return 0;
}

@@ -149,7 +155,7 @@ static u32 prog_ops_moff(const struct bpf_prog *prog)
u32 midx;

midx = prog->expected_attach_type;
- t = bpf_tcp_congestion_ops.type;
+ t = tcp_congestion_ops_type;
m = &btf_type_member(t)[midx];

return __btf_member_bit_offset(t, m) / 8;
--
2.34.1