diff options
Diffstat (limited to 'kernel/bpf/arraymap.c')
| -rw-r--r-- | kernel/bpf/arraymap.c | 37 |
1 files changed, 32 insertions, 5 deletions
diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c index b0799bced518..3608fa1aec8a 100644 --- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -20,8 +20,10 @@ /* Called from syscall */ static struct bpf_map *array_map_alloc(union bpf_attr *attr) { + u32 elem_size, array_size, index_mask, max_entries; + bool unpriv = !capable(CAP_SYS_ADMIN); struct bpf_array *array; - u32 elem_size, array_size; + u64 mask64; /* check sanity of attributes */ if (attr->max_entries == 0 || attr->key_size != 4 || @@ -36,12 +38,33 @@ static struct bpf_map *array_map_alloc(union bpf_attr *attr) elem_size = round_up(attr->value_size, 8); + max_entries = attr->max_entries; + + /* On 32 bit archs roundup_pow_of_two() with max_entries that has + * upper most bit set in u32 space is undefined behavior due to + * resulting 1U << 32, so do it manually here in u64 space. + */ + mask64 = fls_long(max_entries - 1); + mask64 = 1ULL << mask64; + mask64 -= 1; + + index_mask = mask64; + if (unpriv) { + /* round up array size to nearest power of 2, + * since cpu will speculate within index_mask limits + */ + max_entries = index_mask + 1; + /* Check for overflows. */ + if (max_entries < attr->max_entries) + return ERR_PTR(-E2BIG); + } + /* check round_up into zero and u32 overflow */ if (elem_size == 0 || - attr->max_entries > (U32_MAX - PAGE_SIZE - sizeof(*array)) / elem_size) + max_entries > (U32_MAX - PAGE_SIZE - sizeof(*array)) / elem_size) return ERR_PTR(-ENOMEM); - array_size = sizeof(*array) + attr->max_entries * elem_size; + array_size = sizeof(*array) + max_entries * elem_size; /* allocate all map elements and zero-initialize them */ array = kzalloc(array_size, GFP_USER | __GFP_NOWARN); @@ -50,6 +73,8 @@ static struct bpf_map *array_map_alloc(union bpf_attr *attr) if (!array) return ERR_PTR(-ENOMEM); } + array->index_mask = index_mask; + array->map.unpriv_array = unpriv; /* copy mandatory map attributes */ array->map.key_size = attr->key_size; @@ -70,7 +95,7 @@ static void *array_map_lookup_elem(struct bpf_map *map, void *key) if (index >= array->map.max_entries) return NULL; - return array->value + array->elem_size * index; + return array->value + array->elem_size * (index & array->index_mask); } /* Called from syscall */ @@ -111,7 +136,9 @@ static int array_map_update_elem(struct bpf_map *map, void *key, void *value, /* all elements already exist */ return -EEXIST; - memcpy(array->value + array->elem_size * index, value, map->value_size); + memcpy(array->value + + array->elem_size * (index & array->index_mask), + value, map->value_size); return 0; } |