diff mbox series

[v3,bpf-next,1/5] devmap: Formalize map value as a named struct

Message ID 20200529052057.69378-2-dsahern@kernel.org
State Changes Requested
Delegated to: BPF Maintainers
Headers show
Series bpf: Add support for XDP programs in DEVMAP entries | expand

Commit Message

David Ahern May 29, 2020, 5:20 a.m. UTC 
Add 'struct bpf_devmap_val' to the bpf uapi to formalize the
expected values that can be passed in for a DEVMAP.
Update devmap code to use the struct.

Signed-off-by: David Ahern <dsahern@kernel.org>
---
 include/uapi/linux/bpf.h       |  5 +++++
 kernel/bpf/devmap.c            | 40 +++++++++++++++++++---------------
 tools/include/uapi/linux/bpf.h |  5 +++++
 3 files changed, 33 insertions(+), 17 deletions(-)

Comments

Jesper Dangaard Brouer May 29, 2020, 8:22 a.m. UTC | #1 
On Thu, 28 May 2020 23:20:53 -0600
David Ahern <dsahern@kernel.org> wrote:

> Add 'struct bpf_devmap_val' to the bpf uapi to formalize the
> expected values that can be passed in for a DEVMAP.
> Update devmap code to use the struct.
> 
> Signed-off-by: David Ahern <dsahern@kernel.org>
> ---
>  include/uapi/linux/bpf.h       |  5 +++++
>  kernel/bpf/devmap.c            | 40 +++++++++++++++++++---------------
>  tools/include/uapi/linux/bpf.h |  5 +++++
>  3 files changed, 33 insertions(+), 17 deletions(-)
> 
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index 54b93f8b49b8..42c884dfbad9 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -3625,6 +3625,11 @@ struct xdp_md {
>  	__u32 rx_queue_index;  /* rxq->queue_index  */
>  };
>  
> +/* DEVMAP values */
> +struct bpf_devmap_val {
> +	__u32 ifindex;   /* device index */
> +};

We do need this struct bpf_devmap_val, but I think it is wrong to make this UAPI.

A BPF-prog can get this via:  #include "vmlinux.h"
David Ahern May 29, 2020, 3:36 p.m. UTC | #2 
On 5/29/20 2:22 AM, Jesper Dangaard Brouer wrote:
> We do need this struct bpf_devmap_val, but I think it is wrong to make this UAPI.
> 
> A BPF-prog can get this via:  #include "vmlinux.h"

sure. I see that now.

I forgot to fold in a small update to the selftests, so I need to send a
v4 anyways. I will wait until later in the day in case there are other
comments.
Jesper Dangaard Brouer May 29, 2020, 4:02 p.m. UTC | #3 
On Fri, 29 May 2020 09:36:14 -0600
David Ahern <dsahern@gmail.com> wrote:

> On 5/29/20 2:22 AM, Jesper Dangaard Brouer wrote:
> > We do need this struct bpf_devmap_val, but I think it is wrong to make this UAPI.
> > 
> > A BPF-prog can get this via:  #include "vmlinux.h"  
> 
> sure. I see that now.
> 
> I forgot to fold in a small update to the selftests, so I need to send a
> v4 anyways. I will wait until later in the day in case there are other
> comments.

I've just posted a patchset on top of this V3, that moves struct
bpf_devmap_val, and that demonstrate via code that I mean by
leveraging BTF for dynamic config API.

https://lore.kernel.org/netdev/159076794319.1387573.8722376887638960093.stgit@firesoul/
diff mbox series

Patch

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 54b93f8b49b8..42c884dfbad9 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -3625,6 +3625,11 @@  struct xdp_md {
 	__u32 rx_queue_index;  /* rxq->queue_index  */
 };
 
+/* DEVMAP values */
+struct bpf_devmap_val {
+	__u32 ifindex;   /* device index */
+};
+
 enum sk_action {
 	SK_DROP = 0,
 	SK_PASS,
diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
index a51d9fb7a359..2887fe6d1e1d 100644
--- a/kernel/bpf/devmap.c
+++ b/kernel/bpf/devmap.c
@@ -66,6 +66,7 @@  struct bpf_dtab_netdev {
 	struct bpf_dtab *dtab;
 	struct rcu_head rcu;
 	unsigned int idx;
+	struct bpf_devmap_val val;
 };
 
 struct bpf_dtab {
@@ -472,18 +473,15 @@  int dev_map_generic_redirect(struct bpf_dtab_netdev *dst, struct sk_buff *skb,
 static void *dev_map_lookup_elem(struct bpf_map *map, void *key)
 {
 	struct bpf_dtab_netdev *obj = __dev_map_lookup_elem(map, *(u32 *)key);
-	struct net_device *dev = obj ? obj->dev : NULL;
 
-	return dev ? &dev->ifindex : NULL;
+	return obj ? &obj->val : NULL;
 }
 
 static void *dev_map_hash_lookup_elem(struct bpf_map *map, void *key)
 {
 	struct bpf_dtab_netdev *obj = __dev_map_hash_lookup_elem(map,
 								*(u32 *)key);
-	struct net_device *dev = obj ? obj->dev : NULL;
-
-	return dev ? &dev->ifindex : NULL;
+	return obj ? &obj->val : NULL;
 }
 
 static void __dev_map_entry_free(struct rcu_head *rcu)
@@ -541,7 +539,7 @@  static int dev_map_hash_delete_elem(struct bpf_map *map, void *key)
 
 static struct bpf_dtab_netdev *__dev_map_alloc_node(struct net *net,
 						    struct bpf_dtab *dtab,
-						    u32 ifindex,
+						    struct bpf_devmap_val *val,
 						    unsigned int idx)
 {
 	struct bpf_dtab_netdev *dev;
@@ -551,16 +549,18 @@  static struct bpf_dtab_netdev *__dev_map_alloc_node(struct net *net,
 	if (!dev)
 		return ERR_PTR(-ENOMEM);
 
-	dev->dev = dev_get_by_index(net, ifindex);
-	if (!dev->dev) {
-		kfree(dev);
-		return ERR_PTR(-EINVAL);
-	}
+	dev->dev = dev_get_by_index(net, val->ifindex);
+	if (!dev->dev)
+		goto err_out;
 
 	dev->idx = idx;
 	dev->dtab = dtab;
+	dev->val.ifindex = val->ifindex;
 
 	return dev;
+err_out:
+	kfree(dev);
+	return ERR_PTR(-EINVAL);
 }
 
 static int __dev_map_update_elem(struct net *net, struct bpf_map *map,
@@ -568,7 +568,7 @@  static int __dev_map_update_elem(struct net *net, struct bpf_map *map,
 {
 	struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
 	struct bpf_dtab_netdev *dev, *old_dev;
-	u32 ifindex = *(u32 *)value;
+	struct bpf_devmap_val val = { };
 	u32 i = *(u32 *)key;
 
 	if (unlikely(map_flags > BPF_EXIST))
@@ -578,10 +578,13 @@  static int __dev_map_update_elem(struct net *net, struct bpf_map *map,
 	if (unlikely(map_flags == BPF_NOEXIST))
 		return -EEXIST;
 
-	if (!ifindex) {
+	/* already verified value_size <= sizeof val */
+	memcpy(&val, value, map->value_size);
+
+	if (!val.ifindex) {
 		dev = NULL;
 	} else {
-		dev = __dev_map_alloc_node(net, dtab, ifindex, i);
+		dev = __dev_map_alloc_node(net, dtab, &val, i);
 		if (IS_ERR(dev))
 			return PTR_ERR(dev);
 	}
@@ -609,12 +612,15 @@  static int __dev_map_hash_update_elem(struct net *net, struct bpf_map *map,
 {
 	struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
 	struct bpf_dtab_netdev *dev, *old_dev;
-	u32 ifindex = *(u32 *)value;
+	struct bpf_devmap_val val = { };
 	u32 idx = *(u32 *)key;
 	unsigned long flags;
 	int err = -EEXIST;
 
-	if (unlikely(map_flags > BPF_EXIST || !ifindex))
+	/* already verified value_size <= sizeof val */
+	memcpy(&val, value, map->value_size);
+
+	if (unlikely(map_flags > BPF_EXIST || !val.ifindex))
 		return -EINVAL;
 
 	spin_lock_irqsave(&dtab->index_lock, flags);
@@ -623,7 +629,7 @@  static int __dev_map_hash_update_elem(struct net *net, struct bpf_map *map,
 	if (old_dev && (map_flags & BPF_NOEXIST))
 		goto out_err;
 
-	dev = __dev_map_alloc_node(net, dtab, ifindex, idx);
+	dev = __dev_map_alloc_node(net, dtab, &val, idx);
 	if (IS_ERR(dev)) {
 		err = PTR_ERR(dev);
 		goto out_err;
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 54b93f8b49b8..42c884dfbad9 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -3625,6 +3625,11 @@  struct xdp_md {
 	__u32 rx_queue_index;  /* rxq->queue_index  */
 };
 
+/* DEVMAP values */
+struct bpf_devmap_val {
+	__u32 ifindex;   /* device index */
+};
+
 enum sk_action {
 	SK_DROP = 0,
 	SK_PASS,