diff options
| author | Masoud Aghasi <maghasi@disroot.org> | 2026-10-08 13:07:33 +0100 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2026-10-18 22:52:05 +0000 |
| commit | 4a9b25fe8d138f2e0e65b337ecf829ce7ce42d09 (patch) | |
| tree | 1e832fa0a35858c2f2e165a892ef2788e80b989e /kernel/bpf | |
| parent | a898ff0f3e9968b5f7c248d2af3cf1ddaf239e51 (diff) | |
bpf: Fix incorrect handling of user flags by percpu hash map updates
For BPF_MAP_TYPE_PERCPU_HASH and BPF_MAP_TYPE_LRU_PERCPU_HASH maps,
htab_map_check_update_flags() and check_flags() are 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, when using (BPF_F_CPU | BPF_EXIST) or
(BPF_F_CPU | BPF_NOEXIST) flag combinations with bpf_map_update_elem()
on a percpu hash map, the BPF_EXIST flag does not prevent new
insertions as expected and BPF_NOEXIST flag does not prevent
modification of existing entries as expected.
This patch fixes the bug by adding proper flag validations and checks.
Before this patch, htab_map_check_update_flags() rejected
(BPF_F_ALL_CPUS | BPF_EXIST) and (BPF_F_ALL_CPUS | BPF_NOEXIST) with
-EINVAL. After the patch those combinations are accepted.
This patch also starts returning -EINVAL for (BPF_EXIST | BPF_NOEXIST),
with or without BPF_F_CPU, which was previously accepted.
Fixes: c6936161fd55 ("bpf: Add BPF_F_CPU and BPF_F_ALL_CPUS flags support for percpu_hash and lru_percpu_hash maps")
Signed-off-by: Masoud Aghasi <maghasi@disroot.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Leon Hwang <leon.hwang@linux.dev>
Link: https://patch.msgid.link/20261008120734.1565972-3-maghasi@disroot.org
Diffstat (limited to 'kernel/bpf')
| -rw-r--r-- | kernel/bpf/hashtab.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c index 66ebb5a32807..bf78e09f4d51 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c @@ -1367,11 +1367,11 @@ dec_count: static int check_flags(struct bpf_htab *htab, struct htab_elem *l_old, u64 map_flags) { - if (l_old && (map_flags & ~BPF_F_LOCK) == BPF_NOEXIST) + if (l_old && (map_flags & BPF_NOEXIST)) /* elem already exists */ return -EEXIST; - if (!l_old && (map_flags & ~BPF_F_LOCK) == BPF_EXIST) + if (!l_old && (map_flags & BPF_EXIST)) /* elem doesn't exist, cannot update it */ return -ENOENT; @@ -1560,9 +1560,11 @@ err_lock_bucket: static int htab_map_check_update_flags(bool onallcpus, u64 map_flags) { + if (unlikely((map_flags & BPF_EXIST_FLAGS) == BPF_EXIST_FLAGS)) + return -EINVAL; if (unlikely(!onallcpus && map_flags > BPF_EXIST)) return -EINVAL; - if (unlikely(onallcpus && ((map_flags & BPF_F_LOCK) || (u32)map_flags > BPF_F_ALL_CPUS))) + if (unlikely(onallcpus && ((u32)map_flags & ~(BPF_EXIST_FLAGS | BPF_CPU_FLAGS)))) return -EINVAL; return 0; } @@ -1661,7 +1663,7 @@ static long __htab_lru_percpu_map_update_elem(struct bpf_map *map, void *key, * to remove older elem from htab and this removal * operation will need a bucket lock. */ - if (map_flags != BPF_EXIST) { + if (!(map_flags & BPF_EXIST)) { l_new = prealloc_lru_pop(htab, key, hash); if (!l_new) return -ENOMEM; |