On 1/7/20 7:55 PM, Martin Lau wrote:
On Tue, Jan 07, 2020 at 05:00:37PM +0100, Daniel Borkmann wrote:
On 12/31/19 7:20 AM, Martin KaFai Lau wrote:
[...]
[...]
+ err = arch_prepare_bpf_trampoline(image,
+ st_map->image + PAGE_SIZE,
+ &st_ops->func_models[i], 0,
+ &prog, 1, NULL, 0, NULL);
+ if (err < 0)
+ goto reset_unlock;
+
+ *(void **)(kdata + moff) = image;
+ image += err;
+
+ /* put prog_id to udata */
+ *(unsigned long *)(udata + moff) = prog->aux->id;
udata (with all progs' id) will be returned during lookup_elem().
+ }
+
+ refcount_set(&kvalue->refcnt, 1);
+ bpf_map_inc(map);
+
+ err = st_ops->reg(kdata);
+ if (!err) {
+ /* Pair with smp_load_acquire() during lookup */
+ smp_store_release(&kvalue->state, BPF_STRUCT_OPS_STATE_INUSE);
Is there a reason using READ_ONCE/WRITE_ONCE pair is not enough?
The intention is to ensure lookup_elem() can see all the progs' id once
the state is set to BPF_STRUCT_OPS_STATE_INUSE.
Is READ_ONCE/WRITE_ONCE enough to do this?
True, given the above udata store, makes sense as-is.
+ goto unlock;
+ }
+
+ /* Error during st_ops->reg() */
+ bpf_map_put(map);
+
+reset_unlock:
+ bpf_struct_ops_map_put_progs(st_map);
+ memset(uvalue, 0, map->value_size);
+ memset(kvalue, 0, map->value_size);
+
+unlock:
+ spin_unlock(&st_map->lock);
+ return err;
+}
[...]
+static struct bpf_map *bpf_struct_ops_map_alloc(union bpf_attr *attr)
+{
+ const struct bpf_struct_ops *st_ops;
+ size_t map_total_size, st_map_size;
+ struct bpf_struct_ops_map *st_map;
+ const struct btf_type *t, *vt;
+ struct bpf_map_memory mem;
+ struct bpf_map *map;
+ int err;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return ERR_PTR(-EPERM);
+
+ st_ops = bpf_struct_ops_find_value(attr->btf_vmlinux_value_type_id);
+ if (!st_ops)
+ return ERR_PTR(-ENOTSUPP);
+
+ vt = st_ops->value_type;
+ if (attr->value_size != vt->size)
+ return ERR_PTR(-EINVAL);
+
+ t = st_ops->type;
+
+ st_map_size = sizeof(*st_map) +
+ /* kvalue stores the
+ * struct bpf_struct_ops_tcp_congestions_ops
+ */
+ (vt->size - sizeof(struct bpf_struct_ops_value));
+ map_total_size = st_map_size +
+ /* uvalue */
+ sizeof(vt->size) +
+ /* struct bpf_progs **progs */
+ btf_type_vlen(t) * sizeof(struct bpf_prog *);
+ err = bpf_map_charge_init(&mem, map_total_size);
+ if (err < 0)
+ return ERR_PTR(err);
+
+ st_map = bpf_map_area_alloc(st_map_size, NUMA_NO_NODE);
+ if (!st_map) {
+ bpf_map_charge_finish(&mem);
+ return ERR_PTR(-ENOMEM);
+ }
+ st_map->st_ops = st_ops;
+ map = &st_map->map;
+
+ st_map->uvalue = bpf_map_area_alloc(vt->size, NUMA_NO_NODE);
+ st_map->progs =
+ bpf_map_area_alloc(btf_type_vlen(t) * sizeof(struct bpf_prog *),
+ NUMA_NO_NODE);
+ st_map->image = bpf_jit_alloc_exec(PAGE_SIZE);
+ if (!st_map->uvalue || !st_map->progs || !st_map->image) {
+ bpf_struct_ops_map_free(map);
+ bpf_map_charge_finish(&mem);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ spin_lock_init(&st_map->lock);
+ set_vm_flush_reset_perms(st_map->image);
+ set_memory_x((long)st_map->image, 1);
Shouldn't this be using text poke as well once you write the image later on,
otherwise we create yet another instance of W+X memory ... :/
Once image is written in update_elem(), it will never be changed.
I can set it to ro after it is written.
And we could also move the set_memory_x() to that point once image is written and
marked read-only; mid term text poke interface to avoid all this.
Other than that nothing obvious stands out from reviewing patch 1-8, so no objections
from my side.
+ bpf_map_init_from_attr(map, attr);
+ bpf_map_charge_move(&map->memory, &mem);
+
+ return map;
+}
+
+const struct bpf_map_ops bpf_struct_ops_map_ops = {
+ .map_alloc_check = bpf_struct_ops_map_alloc_check,
+ .map_alloc = bpf_struct_ops_map_alloc,
+ .map_free = bpf_struct_ops_map_free,
+ .map_get_next_key = bpf_struct_ops_map_get_next_key,
+ .map_lookup_elem = bpf_struct_ops_map_lookup_elem,
+ .map_delete_elem = bpf_struct_ops_map_delete_elem,
+ .map_update_elem = bpf_struct_ops_map_update_elem,
+ .map_seq_show_elem = bpf_struct_ops_map_seq_show_elem,
+};
[...]
