[PATCH bpf-next v4 03/15] bpf: Add bpf_struct_ops accessor helpers
From: Amery Hung <hidden>
Date: 2026-09-17 20:05:52
Also in:
bpf
Subsystem:
bpf [core], bpf [general] (safe dynamic programs and tools), the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Linus Torvalds
From: Martin KaFai Lau <martin.lau@kernel.org> Add the helper functions bpf_struct_ops_map_kdata() and bpf_struct_ops_map_cfi_stubs() in bpf_struct_ops.c. They will be called from cgroup.c in the upcoming patch to create a struct_ops to cgroup attachment link. bpf_struct_ops_valid_to_reg() is also exposed for the upcoming caller in cgroup.c. The link update validation is also refactored into a new function bpf_struct_ops_link_update_check() such that it can be reused by the caller in cgroup.c in the upcoming patch. Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com> Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org> Signed-off-by: Amery Hung <redacted> --- include/linux/bpf.h | 27 +++++++++++++++++++ kernel/bpf/bpf_struct_ops.c | 53 +++++++++++++++++++++++++++---------- 2 files changed, 66 insertions(+), 14 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 1198404885c8..90ab467d25a2 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h@@ -2290,6 +2290,11 @@ u32 bpf_struct_ops_id(const void *kdata); int bpf_struct_ops_for_each_prog(const void *kdata, int (*cb)(struct bpf_prog *prog, void *data), void *data); +void *bpf_struct_ops_map_kdata(struct bpf_map *map); +void *bpf_struct_ops_map_cfi_stubs(struct bpf_map *map); +bool bpf_struct_ops_valid_to_reg(struct bpf_map *map); +int bpf_struct_ops_link_update_check(struct bpf_map *new_map, struct bpf_map *old_map, + struct bpf_map *expected_old_map); #ifdef CONFIG_NET /* Define it here to avoid the use of forward declaration */
@@ -2354,6 +2359,28 @@ static inline void bpf_map_struct_ops_info_fill(struct bpf_map_info *info, struc static inline void bpf_struct_ops_desc_release(struct bpf_struct_ops_desc *st_ops_desc) { } +static inline u32 bpf_struct_ops_id(void *kdata) +{ + return 0; +} +static inline void *bpf_struct_ops_map_kdata(struct bpf_map *map) +{ + return NULL; +} +static inline void *bpf_struct_ops_map_cfi_stubs(struct bpf_map *map) +{ + return NULL; +} +static inline bool bpf_struct_ops_valid_to_reg(struct bpf_map *map) +{ + return false; +} +static inline int bpf_struct_ops_link_update_check(struct bpf_map *new_map, + struct bpf_map *old_map, + struct bpf_map *expected_old_map) +{ + return -EOPNOTSUPP; +} #endif
diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c
index 7802859eac1e..12ce9654ffdd 100644
--- a/kernel/bpf/bpf_struct_ops.c
+++ b/kernel/bpf/bpf_struct_ops.c@@ -1276,7 +1276,23 @@ int bpf_struct_ops_for_each_prog(const void *kdata, } EXPORT_SYMBOL_GPL(bpf_struct_ops_for_each_prog); -static bool bpf_struct_ops_valid_to_reg(struct bpf_map *map) +void *bpf_struct_ops_map_kdata(struct bpf_map *map) +{ + struct bpf_struct_ops_map *st_map; + + st_map = container_of(map, struct bpf_struct_ops_map, map); + return st_map->kvalue.data; +} + +void *bpf_struct_ops_map_cfi_stubs(struct bpf_map *map) +{ + struct bpf_struct_ops_map *st_map; + + st_map = container_of(map, struct bpf_struct_ops_map, map); + return st_map->st_ops_desc->st_ops->cfi_stubs; +} + +bool bpf_struct_ops_valid_to_reg(struct bpf_map *map) { struct bpf_struct_ops_map *st_map = (struct bpf_struct_ops_map *)map;
@@ -1329,6 +1345,26 @@ static int bpf_struct_ops_map_link_fill_link_info(const struct bpf_link *link, return 0; } +int bpf_struct_ops_link_update_check(struct bpf_map *new_map, + struct bpf_map *old_map, + struct bpf_map *expected_old_map) +{ + struct bpf_struct_ops_map *st_map, *old_st_map; + + if (!old_map) + return -ENOLINK; + if (expected_old_map && old_map != expected_old_map) + return -EPERM; + + st_map = container_of(new_map, struct bpf_struct_ops_map, 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_desc != old_st_map->st_ops_desc) + return -EINVAL; + + return 0; +} + static int bpf_struct_ops_map_link_update(struct bpf_link *link, struct bpf_map *new_map, struct bpf_map *expected_old_map) {
@@ -1347,23 +1383,12 @@ static int bpf_struct_ops_map_link_update(struct bpf_link *link, struct bpf_map return -EOPNOTSUPP; mutex_lock(&update_mutex); - old_map = st_link->map; - if (!old_map) { - err = -ENOLINK; - goto err_out; - } - if (expected_old_map && old_map != expected_old_map) { - err = -EPERM; + err = bpf_struct_ops_link_update_check(new_map, old_map, expected_old_map); + if (err) goto err_out; - } 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_desc != old_st_map->st_ops_desc) { - err = -EINVAL; - goto err_out; - } err = st_map->st_ops_desc->st_ops->update(st_map->kvalue.data, old_st_map->kvalue.data, link); if (err)
--
2.52.0