Re: [RFC PATCH bpf-next 1/2] xdp: add dev map multicast support

Hangbin Liu
2020-04-20T09:52:36Z

Hi Daniel,

Would you please help review the RFC and give some comments?
Especially for the ifindex parameter of bpf_redirect_map() which
contains both include and exclude map id. Should we keep the current
designing, or find a way to make it flexible, or even add a new syscall
to accept two index parameters?

Thanks
Hangbin

On Wed, Apr 15, 2020 at 04:54:36PM +0800, Hangbin Liu wrote:
> This is a prototype for xdp multicast support. In this implemention we
> use map-in-map to store the multicast groups, because we may have both
> include and exclude groups on one interface.
>
> The include and exclude groups are seperated by a 32 bits map key.
> the high 16 bits keys are used for include groups and low 16 bits
> keys are for exclude groups.
>
> The general data path is kept in net/core/filter.c. The native data
> path is in kernel/bpf/devmap.c so we can use direct calls to
> get better performace.
>
> Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
> ---
> include/linux/bpf.h | 29 +++++++++++
> include/net/xdp.h | 1 +
> kernel/bpf/arraymap.c | 2 +-
> kernel/bpf/devmap.c | 118 ++++++++++++++++++++++++++++++++++++++++++
> kernel/bpf/hashtab.c | 2 +-
> kernel/bpf/verifier.c | 15 +++++-
> net/core/filter.c | 69 +++++++++++++++++++++++-
> net/core/xdp.c | 26 ++++++++++
> 8 files changed, 256 insertions(+), 6 deletions(-)
>
> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index fd2b2322412d..72797667bca8 100644
> --- a/include/linux/bpf.h
> +++ b/include/linux/bpf.h
> @@ -1156,11 +1156,17 @@ struct sk_buff;
>
> struct bpf_dtab_netdev *__dev_map_lookup_elem(struct bpf_map *map, u32 key);
> struct bpf_dtab_netdev *__dev_map_hash_lookup_elem(struct bpf_map *map, u32 key);
> +void *array_of_map_lookup_elem(struct bpf_map *map, void *key);
> +void *htab_of_map_lookup_elem(struct bpf_map *map, void *key);
> void __dev_flush(void);
> int dev_xdp_enqueue(struct net_device *dev, struct xdp_buff *xdp,
> struct net_device *dev_rx);
> int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_buff *xdp,
> struct net_device *dev_rx);
> +bool dev_in_exclude_map(struct bpf_dtab_netdev *obj, struct bpf_map *map);
> +int dev_map_enqueue_multi(struct xdp_buff *xdp, struct net_device *dev_rx,
> + struct bpf_map *map, u32 index);
> +
> int dev_map_generic_redirect(struct bpf_dtab_netdev *dst, struct sk_buff *skb,
> struct bpf_prog *xdp_prog);
>
> @@ -1276,6 +1282,16 @@ static inline struct net_device *__dev_map_hash_lookup_elem(struct bpf_map *map
> return NULL;
> }
>
> +static void *array_of_map_lookup_elem(struct bpf_map *map, void *key)
> +{
> +
> +}
> +
> +static void *htab_of_map_lookup_elem(struct bpf_map *map, void *key)
> +{
> +
> +}
> +
> static inline void __dev_flush(void)
> {
> }
> @@ -1297,6 +1313,19 @@ int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_buff *xdp,
> return 0;
> }
>
> +static inline
> +bool dev_in_exclude_map(struct bpf_dtab_netdev *obj, struct bpf_map *map)
> +{
> + return true;
> +}
> +
> +static inline
> +int dev_map_enqueue_multi(struct xdp_buff *xdp, struct net_device *dev_rx,
> + struct bpf_map *map, u32 index)
> +{
> + return 0;
> +}
> +
> struct sk_buff;
>
> static inline int dev_map_generic_redirect(struct bpf_dtab_netdev *dst,
> diff --git a/include/net/xdp.h b/include/net/xdp.h
> index 40c6d3398458..a214dce8579c 100644
> --- a/include/net/xdp.h
> +++ b/include/net/xdp.h
> @@ -92,6 +92,7 @@ static inline void xdp_scrub_frame(struct xdp_frame *frame)
> }
>
> struct xdp_frame *xdp_convert_zc_to_xdp_frame(struct xdp_buff *xdp);
> +struct xdp_frame *xdpf_clone(struct xdp_frame *xdpf);
>
> /* Convert xdp_buff to xdp_frame */
> static inline
> diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
> index 95d77770353c..26ac66a05015 100644
> --- a/kernel/bpf/arraymap.c
> +++ b/kernel/bpf/arraymap.c
> @@ -1031,7 +1031,7 @@ static void array_of_map_free(struct bpf_map *map)
> fd_array_map_free(map);
> }
>
> -static void *array_of_map_lookup_elem(struct bpf_map *map, void *key)
> +void *array_of_map_lookup_elem(struct bpf_map *map, void *key)
> {
> struct bpf_map **inner_map = array_map_lookup_elem(map, key);
>
> diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
> index 58bdca5d978a..3a60cb209ae1 100644
> --- a/kernel/bpf/devmap.c
> +++ b/kernel/bpf/devmap.c
> @@ -85,6 +85,9 @@ static DEFINE_PER_CPU(struct list_head, dev_flush_list);
> static DEFINE_SPINLOCK(dev_map_lock);
> static LIST_HEAD(dev_map_list);
>
> +static void *dev_map_lookup_elem(struct bpf_map *map, void *key);
> +static void *dev_map_hash_lookup_elem(struct bpf_map *map, void *key);
> +
> static struct hlist_head *dev_map_create_hash(unsigned int entries)
> {
> int i;
> @@ -456,6 +459,121 @@ int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_buff *xdp,
> return __xdp_enqueue(dev, xdp, dev_rx);
> }
>
> +/* Use direct call in fast path instead of map->ops->map_get_next_key() */
> +static int devmap_get_next_key(struct bpf_map *map, void *key, void *next_key)
> +{
> +
> + switch (map->map_type) {
> + case BPF_MAP_TYPE_DEVMAP:
> + return dev_map_get_next_key(map, key, next_key);
> + case BPF_MAP_TYPE_DEVMAP_HASH:
> + return dev_map_hash_get_next_key(map, key, next_key);
> + default:
> + break;
> + }
> +
> + return -ENOENT;
> +}
> +
> +bool dev_in_exclude_map(struct bpf_dtab_netdev *obj, struct bpf_map *map)
> +{
> + struct bpf_dtab_netdev *in_obj = NULL;
> + u32 key, next_key;
> + int err;
> +
> + devmap_get_next_key(map, NULL, &key);
> +
> + for (;;) {
> + switch (map->map_type) {
> + case BPF_MAP_TYPE_DEVMAP:
> + in_obj = __dev_map_lookup_elem(map, key);
> + break;
> + case BPF_MAP_TYPE_DEVMAP_HASH:
> + in_obj = __dev_map_hash_lookup_elem(map, key);
> + break;
> + default:
> + break;
> + }
> +
> + if (in_obj && in_obj->dev->ifindex == obj->dev->ifindex)
> + return true;
> +
> + err = devmap_get_next_key(map, &key, &next_key);
> +
> + if (err)
> + break;
> +
> + key = next_key;
> + }
> +
> + return false;
> +}
> +
> +int dev_map_enqueue_multi(struct xdp_buff *xdp, struct net_device *dev_rx,
> + struct bpf_map *map, u32 index)
> +{
> + struct bpf_dtab_netdev *obj = NULL;
> + struct bpf_map *in_map, *ex_map;
> + struct xdp_frame *xdpf, *nxdpf;
> + struct net_device *dev;
> + u32 in_index, ex_index;
> + u32 key, next_key;
> + int err;
> +
> + in_index = index >> 16;
> + in_index = in_index << 16;
> + ex_index = in_index ^ index;
> +
> + in_map = map->ops->map_lookup_elem(map, &in_index);
> + /* ex_map could be NULL */
> + ex_map = map->ops->map_lookup_elem(map, &ex_index);
> +
> + devmap_get_next_key(in_map, NULL, &key);
> +
> + xdpf = convert_to_xdp_frame(xdp);
> + if (unlikely(!xdpf))
> + return -EOVERFLOW;
> +
> + for (;;) {
> + switch (in_map->map_type) {
> + case BPF_MAP_TYPE_DEVMAP:
> + obj = __dev_map_lookup_elem(in_map, key);
> + break;
> + case BPF_MAP_TYPE_DEVMAP_HASH:
> + obj = __dev_map_hash_lookup_elem(in_map, key);
> + break;
> + default:
> + break;
> + }
> + if (!obj)
> + goto find_next;
> +
> + if (ex_map && !dev_in_exclude_map(obj, ex_map)) {
> + dev = obj->dev;
> +
> + if (!dev->netdev_ops->ndo_xdp_xmit)
> + return -EOPNOTSUPP;
> +
> + err = xdp_ok_fwd_dev(dev, xdp->data_end - xdp->data);
> + if (unlikely(err))
> + return err;
> +
> + nxdpf = xdpf_clone(xdpf);
> + if (unlikely(!nxdpf))
> + return -ENOMEM;
> +
> + bq_enqueue(dev, nxdpf, dev_rx);
> + }
> +find_next:
> + err = devmap_get_next_key(in_map, &key, &next_key);
> + if (err)
> + break;
> + key = next_key;
> + }
> +
> + return 0;
> +}
> +
> int dev_map_generic_redirect(struct bpf_dtab_netdev *dst, struct sk_buff *skb,
> struct bpf_prog *xdp_prog)
> {
> diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
> index d541c8486c95..4e0a2eebd38d 100644
> --- a/kernel/bpf/hashtab.c
> +++ b/kernel/bpf/hashtab.c
> @@ -1853,7 +1853,7 @@ static struct bpf_map *htab_of_map_alloc(union bpf_attr *attr)
> return map;
> }
>
> -static void *htab_of_map_lookup_elem(struct bpf_map *map, void *key)
> +void *htab_of_map_lookup_elem(struct bpf_map *map, void *key)
> {
> struct bpf_map **inner_map = htab_map_lookup_elem(map, key);
>
> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index 04c6630cc18f..84d23418823a 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -3898,7 +3898,9 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env,
> break;
> case BPF_MAP_TYPE_ARRAY_OF_MAPS:
> case BPF_MAP_TYPE_HASH_OF_MAPS:
> - if (func_id != BPF_FUNC_map_lookup_elem)
> + /* Used by multicast redirect */
> + if (func_id != BPF_FUNC_redirect_map &&
> + func_id != BPF_FUNC_map_lookup_elem)
> goto error;
> break;
> case BPF_MAP_TYPE_SOCKMAP:
> @@ -3968,8 +3970,17 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env,
> if (map->map_type != BPF_MAP_TYPE_DEVMAP &&
> map->map_type != BPF_MAP_TYPE_DEVMAP_HASH &&
> map->map_type != BPF_MAP_TYPE_CPUMAP &&
> - map->map_type != BPF_MAP_TYPE_XSKMAP)
> + map->map_type != BPF_MAP_TYPE_XSKMAP &&
> + map->map_type != BPF_MAP_TYPE_ARRAY_OF_MAPS &&
> + map->map_type != BPF_MAP_TYPE_HASH_OF_MAPS)
> goto error;
> + if (map->map_type == BPF_MAP_TYPE_ARRAY_OF_MAPS ||
> + map->map_type == BPF_MAP_TYPE_HASH_OF_MAPS) {
> + /* FIXME: Maybe we should also strict the key size here ?? */
> + if (map->inner_map_meta->map_type != BPF_MAP_TYPE_DEVMAP &&
> + map->inner_map_meta->map_type != BPF_MAP_TYPE_DEVMAP_HASH)
> + goto error;
> + }
> break;
> case BPF_FUNC_sk_redirect_map:
> case BPF_FUNC_msg_redirect_map:
> diff --git a/net/core/filter.c b/net/core/filter.c
> index 7628b947dbc3..7d2076f5b0a4 100644
> --- a/net/core/filter.c
> +++ b/net/core/filter.c
> @@ -3473,12 +3473,17 @@ static const struct bpf_func_proto bpf_xdp_adjust_meta_proto = {
> };
>
> static int __bpf_tx_xdp_map(struct net_device *dev_rx, void *fwd,
> - struct bpf_map *map, struct xdp_buff *xdp)
> + struct bpf_map *map, struct xdp_buff *xdp,
> + u32 index)
> {
> switch (map->map_type) {
> case BPF_MAP_TYPE_DEVMAP:
> + /* fall through */
> case BPF_MAP_TYPE_DEVMAP_HASH:
> return dev_map_enqueue(fwd, xdp, dev_rx);
> + case BPF_MAP_TYPE_HASH_OF_MAPS:
> + case BPF_MAP_TYPE_ARRAY_OF_MAPS:
> + return dev_map_enqueue_multi(xdp, dev_rx, map, index);
> case BPF_MAP_TYPE_CPUMAP:
> return cpu_map_enqueue(fwd, xdp, dev_rx);
> case BPF_MAP_TYPE_XSKMAP:
> @@ -3508,6 +3513,10 @@ static inline void *__xdp_map_lookup_elem(struct bpf_map *map, u32 index)
> return __cpu_map_lookup_elem(map, index);
> case BPF_MAP_TYPE_XSKMAP:
> return __xsk_map_lookup_elem(map, index);
> + case BPF_MAP_TYPE_ARRAY_OF_MAPS:
> + return array_of_map_lookup_elem(map, (index >> 16) << 16);
> + case BPF_MAP_TYPE_HASH_OF_MAPS:
> + return htab_of_map_lookup_elem(map, (index >> 16) << 16);
> default:
> return NULL;
> }
> @@ -3552,7 +3561,7 @@ int xdp_do_redirect(struct net_device *dev, struct xdp_buff *xdp,
>
> err = dev_xdp_enqueue(fwd, xdp, dev);
> } else {
> - err = __bpf_tx_xdp_map(dev, fwd, map, xdp);
> + err = __bpf_tx_xdp_map(dev, fwd, map, xdp, index);
> }
>
> if (unlikely(err))
> @@ -3566,6 +3575,55 @@ int xdp_do_redirect(struct net_device *dev, struct xdp_buff *xdp,
> }
> EXPORT_SYMBOL_GPL(xdp_do_redirect);
>
> +static int dev_map_redirect_multi(struct sk_buff *skb, struct bpf_prog *xdp_prog,
> + struct bpf_map *map, u32 index)
> +
> +{
> + struct bpf_map *in_map, *ex_map;
> + struct bpf_dtab_netdev *dst;
> + u32 in_index, ex_index;
> + struct sk_buff *nskb;
> + u32 key, next_key;
> + int err;
> + void *fwd;
> +
> + in_index = index >> 16;
> + in_index = in_index << 16;
> + ex_index = in_index ^ index;
> +
> + in_map = map->ops->map_lookup_elem(map, &in_index);
> + /* ex_map could be NULL */
> + ex_map = map->ops->map_lookup_elem(map, &ex_index);
> +
> + in_map->ops->map_get_next_key(in_map, NULL, &key);
> +
> + for (;;) {
> + fwd = __xdp_map_lookup_elem(in_map, key);
> + if (fwd) {
> + dst = (struct bpf_dtab_netdev *)fwd;
> + if (ex_map && dev_in_exclude_map(dst, ex_map))
> + goto find_next;
> +
> + nskb = skb_clone(skb, GFP_ATOMIC);
> + if (!nskb)
> + return -EOVERFLOW;
> +
> + err = dev_map_generic_redirect(dst, nskb, xdp_prog);
> + if (unlikely(err))
> + return err;
> + }
> +
> +find_next:
> + err = in_map->ops->map_get_next_key(in_map, &key, &next_key);
> + if (err)
> + break;
> +
> + key = next_key;
> + }
> +
> + return 0;
> +}
> +
> static int xdp_do_generic_redirect_map(struct net_device *dev,
> struct sk_buff *skb,
> struct xdp_buff *xdp,
> @@ -3588,6 +3646,13 @@ static int xdp_do_generic_redirect_map(struct net_device *dev,
> err = dev_map_generic_redirect(dst, skb, xdp_prog);
> if (unlikely(err))
> goto err;
> + } else if (map->map_type == BPF_MAP_TYPE_ARRAY_OF_MAPS ||
> + map->map_type == BPF_MAP_TYPE_HASH_OF_MAPS) {
> + /* Do multicast redirecting */
> + err = dev_map_redirect_multi(skb, xdp_prog, map, index);
> + if (unlikely(err))
> + goto err;
> + consume_skb(skb);
> } else if (map->map_type == BPF_MAP_TYPE_XSKMAP) {
> struct xdp_sock *xs = fwd;
>
> diff --git a/net/core/xdp.c b/net/core/xdp.c
> index 4c7ea85486af..70dfb4910f84 100644
> --- a/net/core/xdp.c
> +++ b/net/core/xdp.c
> @@ -496,3 +496,29 @@ struct xdp_frame *xdp_convert_zc_to_xdp_frame(struct xdp_buff *xdp)
> return xdpf;
> }
> EXPORT_SYMBOL_GPL(xdp_convert_zc_to_xdp_frame);
> +
> +struct xdp_frame *xdpf_clone(struct xdp_frame *xdpf)
> +{
> + unsigned int headroom, totalsize;
> + struct xdp_frame *nxdpf;
> + struct page *page;
> + void *addr;
> +
> + headroom = xdpf->headroom + sizeof(*xdpf);
> + totalsize = headroom + xdpf->len;
> +
> + if (unlikely(totalsize > PAGE_SIZE))
> + return NULL;
> + page = dev_alloc_page();
> + if (!page)
> + return NULL;
> + addr = page_to_virt(page);
> +
> + memcpy(addr, xdpf, totalsize);
> +
> + nxdpf = addr;
> + nxdpf->data = addr + headroom;
> +
> + return nxdpf;
> +}
> +EXPORT_SYMBOL_GPL(xdpf_clone);
> --
> 2.19.2
>