For BPF_MAP_TYPE_PERCPU_ARRAY map, bpf_percpu_array_update() is not considering the possibility of a combination of (BPF_NOEXIST, BPF_EXIST) flags with (BPF_F_CPU, BPF_F_ALL_CPUS) flags. This causes the (BPF_NOEXIST, BPF_EXIST) flags to lose their effect in some cases. For example, using the (BPF_F_ALL_CPUS | BPF_EXIST) flag combination with bpf_map_update_elem() results in an incorrect EINVAL error response, even though the flag combination is valid. This patch fixes the bug by adding proper flag validations and checks. Before this patch, bpf_percpu_array_update() rejected BPF_F_ALL_CPUS | BPF_EXIST and BPF_F_ALL_CPUS | BPF_NOEXIST with -EINVAL. Also the BPF_F_CPU | BPF_NOEXIST were accepted. After the patch BPF_F_ALL_CPUS | BPF_EXIST is accepted and BPF_F_ALL_CPUS | BPF_NOEXIST and BPF_F_CPU | BPF_NOEXIST result in -EEXIST. Fixes: 8eb76cb03f0f ("bpf: Add BPF_F_CPU and BPF_F_ALL_CPUS flags support for percpu_array maps") Signed-off-by: Masoud Aghasi --- include/linux/bpf.h | 3 +++ kernel/bpf/arraymap.c | 6 +++--- 2 files changed, 6 insertions(+), 3 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 4bae3796c42f..2efa8fdbb737 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -4322,6 +4322,9 @@ static inline bool bpf_map_is_percpu_map(enum bpf_map_type map_type) } } +#define BPF_EXIST_FLAGS (BPF_EXIST | BPF_NOEXIST) +#define BPF_CPU_FLAGS (BPF_F_CPU | BPF_F_ALL_CPUS) + static inline int bpf_map_check_op_flags(struct bpf_map *map, u64 flags, u64 allowed_flags) { u32 cpu; diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c index 0fe9afd4a591..133f189bf6d2 100644 --- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -438,15 +438,15 @@ int bpf_percpu_array_update(struct bpf_map *map, void *key, void *value, u32 size; int cpu, off = 0; - if (unlikely((map_flags & BPF_F_LOCK) || (u32)map_flags > BPF_F_ALL_CPUS)) - /* unknown flags */ + if (unlikely(((map_flags & BPF_EXIST_FLAGS) == BPF_EXIST_FLAGS) || + ((u32)map_flags & ~(BPF_EXIST_FLAGS | BPF_CPU_FLAGS)))) return -EINVAL; if (unlikely(index >= array->map.max_entries)) /* all elements were pre-allocated, cannot insert a new one */ return -E2BIG; - if (unlikely(map_flags == BPF_NOEXIST)) + if (unlikely(map_flags & BPF_NOEXIST)) /* all elements already exist */ return -EEXIST; -- 2.47.3