Disallow combining BPF_F_LOCK with map values that contain special BTF fields other than bpf_spin_lock (e.g. kptr or uptr). Such mixing may lead to subtle or undefined behavior in map value handling. Reject these combinations early by returning -EOPNOTSUPP.
Centralize map update flag validation in bpf_map_check_op_flags() and reuse it across array, hash, local-storage, and task-storage map update paths. Explicitly reject incompatible BPF_NOEXIST/BPF_EXIST combinations and invalid BPF_F_LOCK usage to keep flag validation consistent and eliminate duplicated per-map checks. Signed-off-by: Leon Hwang <[email protected]> --- include/linux/bpf.h | 7 +++++++ kernel/bpf/arraymap.c | 11 ++++------- kernel/bpf/bpf_local_storage.c | 7 ------- kernel/bpf/bpf_task_storage.c | 3 --- kernel/bpf/hashtab.c | 8 +++----- kernel/bpf/syscall.c | 4 +++- 6 files changed, 17 insertions(+), 23 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 5936f8e2996f..c5863487ee73 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -3935,9 +3935,16 @@ static inline int bpf_map_check_op_flags(struct bpf_map *map, u64 flags, u64 all if ((u32)flags & ~allowed_flags) return -EINVAL; + /* BPF_NOEXIST and BPF_EXIST are mutually exclusive. */ + if ((flags & (BPF_NOEXIST | BPF_EXIST)) == (BPF_NOEXIST | BPF_EXIST)) + return -EINVAL; + if ((flags & BPF_F_LOCK) && !btf_record_has_field(map->record, BPF_SPIN_LOCK)) return -EINVAL; + if ((flags & BPF_F_LOCK) && btf_record_has_field(map->record, ~BPF_SPIN_LOCK)) + return -EOPNOTSUPP; + if (!(flags & BPF_F_CPU) && flags >> 32) return -EINVAL; diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c index 67e9e811de3a..1cff40f109cd 100644 --- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -366,10 +366,7 @@ static long array_map_update_elem(struct bpf_map *map, void *key, void *value, struct bpf_array *array = container_of(map, struct bpf_array, map); u32 index = *(u32 *)key; char *val; - - if (unlikely((map_flags & ~BPF_F_LOCK) > BPF_EXIST)) - /* unknown flags */ - return -EINVAL; + int err; if (unlikely(index >= array->map.max_entries)) /* all elements were pre-allocated, cannot insert a new one */ @@ -379,9 +376,9 @@ static long array_map_update_elem(struct bpf_map *map, void *key, void *value, /* all elements already exist */ return -EEXIST; - if (unlikely((map_flags & BPF_F_LOCK) && - !btf_record_has_field(map->record, BPF_SPIN_LOCK))) - return -EINVAL; + err = bpf_map_check_op_flags(map, map_flags, BPF_EXIST | BPF_F_LOCK); + if (unlikely(err)) + return err; if (array->map.map_type == BPF_MAP_TYPE_PERCPU_ARRAY) { val = this_cpu_ptr(array->pptrs[index & array->index_mask]); diff --git a/kernel/bpf/bpf_local_storage.c b/kernel/bpf/bpf_local_storage.c index e2fe6c32822b..80b50091cbbf 100644 --- a/kernel/bpf/bpf_local_storage.c +++ b/kernel/bpf/bpf_local_storage.c @@ -493,13 +493,6 @@ bpf_local_storage_update(void *owner, struct bpf_local_storage_map *smap, unsigned long flags; int err; - /* BPF_EXIST and BPF_NOEXIST cannot be both set */ - if (unlikely((map_flags & ~BPF_F_LOCK) > BPF_EXIST) || - /* BPF_F_LOCK can only be used in a value with spin_lock */ - unlikely((map_flags & BPF_F_LOCK) && - !btf_record_has_field(smap->map.record, BPF_SPIN_LOCK))) - return ERR_PTR(-EINVAL); - if (gfp_flags == GFP_KERNEL && (map_flags & ~BPF_F_LOCK) != BPF_NOEXIST) return ERR_PTR(-EINVAL); diff --git a/kernel/bpf/bpf_task_storage.c b/kernel/bpf/bpf_task_storage.c index a1dc1bf0848a..21d84818e64e 100644 --- a/kernel/bpf/bpf_task_storage.c +++ b/kernel/bpf/bpf_task_storage.c @@ -125,9 +125,6 @@ static long bpf_pid_task_storage_update_elem(struct bpf_map *map, void *key, struct pid *pid; int fd, err; - if ((map_flags & BPF_F_LOCK) && btf_record_has_field(map->record, BPF_UPTR)) - return -EOPNOTSUPP; - fd = *(int *)key; pid = pidfd_get_pid(fd, &f_flags); if (IS_ERR(pid)) diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c index 3b9d297a53be..2f6ed3e80308 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c @@ -1093,9 +1093,9 @@ static long htab_map_update_elem(struct bpf_map *map, void *key, void *value, u32 key_size, hash; int ret; - if (unlikely((map_flags & ~BPF_F_LOCK) > BPF_EXIST)) - /* unknown flags */ - return -EINVAL; + ret = bpf_map_check_op_flags(map, map_flags, BPF_NOEXIST | BPF_EXIST | BPF_F_LOCK); + if (unlikely(ret)) + return ret; WARN_ON_ONCE(!bpf_rcu_lock_held()); @@ -1107,8 +1107,6 @@ static long htab_map_update_elem(struct bpf_map *map, void *key, void *value, head = &b->head; if (unlikely(map_flags & BPF_F_LOCK)) { - if (unlikely(!btf_record_has_field(map->record, BPF_SPIN_LOCK))) - return -EINVAL; /* find an element without taking the bucket lock */ l_old = lookup_nulls_elem_raw(head, hash, key, key_size, htab->n_buckets); diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 3c5c03d43f5f..49e424e5f492 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -1780,6 +1780,7 @@ static int map_update_elem(union bpf_attr *attr, bpfptr_t uattr) bpfptr_t uvalue = make_bpfptr(attr->value, uattr.is_kernel); struct bpf_map *map; void *key, *value; + u64 allowed_flags; u32 value_size; int err; @@ -1796,7 +1797,8 @@ static int map_update_elem(union bpf_attr *attr, bpfptr_t uattr) goto err_put; } - err = bpf_map_check_op_flags(map, attr->flags, ~0); + allowed_flags = BPF_NOEXIST | BPF_EXIST | BPF_F_LOCK | BPF_F_CPU | BPF_F_ALL_CPUS; + err = bpf_map_check_op_flags(map, attr->flags, allowed_flags); if (err) goto err_put; -- 2.52.0
