1 files changed, 200 insertions, 0 deletions

diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
index a0501266bdb8..9af048a932b5 100644
--- a/kernel/bpf/devmap.c
+++ b/kernel/bpf/devmap.c
@@ -37,6 +37,12 @@
  * notifier hook walks the map we know that new dev references can not be
  * added by the user because core infrastructure ensures dev_get_by_index()
  * calls will fail at this point.
+ *
+ * The devmap_hash type is a map type which interprets keys as ifindexes and
+ * indexes these using a hashmap. This allows maps that use ifindex as key to be
+ * densely packed instead of having holes in the lookup array for unused
+ * ifindexes. The setup and packet enqueue/send code is shared between the two
+ * types of devmap; only the lookup and insertion is different.
  */
 #include <linux/bpf.h>
 #include <net/xdp.h>
@@ -59,6 +65,7 @@ struct xdp_bulk_queue {
 
 struct bpf_dtab_netdev {
         struct net_device *dev; /* must be first member, due to tracepoint */
+        struct hlist_node index_hlist;
         struct bpf_dtab *dtab;
         struct xdp_bulk_queue __percpu *bulkq;
         struct rcu_head rcu;
@@ -70,11 +77,30 @@ struct bpf_dtab {
         struct bpf_dtab_netdev **netdev_map;
         struct list_head __percpu *flush_list;
         struct list_head list;
+
+        /* these are only used for DEVMAP_HASH type maps */
+        struct hlist_head *dev_index_head;
+        spinlock_t index_lock;
+        unsigned int items;
+        u32 n_buckets;
 };
 
 static DEFINE_SPINLOCK(dev_map_lock);
 static LIST_HEAD(dev_map_list);
 
+static struct hlist_head *dev_map_create_hash(unsigned int entries)
+{
+        int i;
+        struct hlist_head *hash;
+
+        hash = kmalloc_array(entries, sizeof(*hash), GFP_KERNEL);
+        if (hash != NULL)
+                for (i = 0; i < entries; i++)
+                        INIT_HLIST_HEAD(&hash[i]);
+
+        return hash;
+}
+
 static int dev_map_init_map(struct bpf_dtab *dtab, union bpf_attr *attr)
 {
         int err, cpu;
@@ -97,6 +123,14 @@ static int dev_map_init_map(struct bpf_dtab *dtab, union bpf_attr *attr)
         cost = (u64) dtab->map.max_entries * sizeof(struct bpf_dtab_netdev *);
         cost += sizeof(struct list_head) * num_possible_cpus();
 
+        if (attr->map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
+                dtab->n_buckets = roundup_pow_of_two(dtab->map.max_entries);
+
+                if (!dtab->n_buckets) /* Overflow check */
+                        return -EINVAL;
+                cost += sizeof(struct hlist_head) * dtab->n_buckets;
+        }
+
         /* if map size is larger than memlock limit, reject it */
         err = bpf_map_charge_init(&dtab->map.memory, cost);
         if (err)
@@ -115,8 +149,18 @@ static int dev_map_init_map(struct bpf_dtab *dtab, union bpf_attr *attr)
         if (!dtab->netdev_map)
                 goto free_percpu;
 
+        if (attr->map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
+                dtab->dev_index_head = dev_map_create_hash(dtab->n_buckets);
+                if (!dtab->dev_index_head)
+                        goto free_map_area;
+
+                spin_lock_init(&dtab->index_lock);
+        }
+
         return 0;
 
+free_map_area:
+        bpf_map_area_free(dtab->netdev_map);
 free_percpu:
         free_percpu(dtab->flush_list);
 free_charge:
@@ -198,6 +242,7 @@ static void dev_map_free(struct bpf_map *map)
 
         free_percpu(dtab->flush_list);
         bpf_map_area_free(dtab->netdev_map);
+        kfree(dtab->dev_index_head);
         kfree(dtab);
 }
 
@@ -218,6 +263,70 @@ static int dev_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
         return 0;
 }
 
+static inline struct hlist_head *dev_map_index_hash(struct bpf_dtab *dtab,
+                                                    int idx)
+{
+        return &dtab->dev_index_head[idx & (dtab->n_buckets - 1)];
+}
+
+struct bpf_dtab_netdev *__dev_map_hash_lookup_elem(struct bpf_map *map, u32 key)
+{
+        struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
+        struct hlist_head *head = dev_map_index_hash(dtab, key);
+        struct bpf_dtab_netdev *dev;
+
+        hlist_for_each_entry_rcu(dev, head, index_hlist)
+                if (dev->idx == key)
+                        return dev;
+
+        return NULL;
+}
+
+static int dev_map_hash_get_next_key(struct bpf_map *map, void *key,
+                                    void *next_key)
+{
+        struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
+        u32 idx, *next = next_key;
+        struct bpf_dtab_netdev *dev, *next_dev;
+        struct hlist_head *head;
+        int i = 0;
+
+        if (!key)
+                goto find_first;
+
+        idx = *(u32 *)key;
+
+        dev = __dev_map_hash_lookup_elem(map, idx);
+        if (!dev)
+                goto find_first;
+
+        next_dev = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu(&dev->index_hlist)),
+                                    struct bpf_dtab_netdev, index_hlist);
+
+        if (next_dev) {
+                *next = next_dev->idx;
+                return 0;
+        }
+
+        i = idx & (dtab->n_buckets - 1);
+        i++;
+
+ find_first:
+        for (; i < dtab->n_buckets; i++) {
+                head = dev_map_index_hash(dtab, i);
+
+                next_dev = hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(head)),
+                                            struct bpf_dtab_netdev,
+                                            index_hlist);
+                if (next_dev) {
+                        *next = next_dev->idx;
+                        return 0;
+                }
+        }
+
+        return -ENOENT;
+}
+
 static int bq_xmit_all(struct xdp_bulk_queue *bq, u32 flags,
                        bool in_napi_ctx)
 {
@@ -373,6 +482,15 @@ static void *dev_map_lookup_elem(struct bpf_map *map, void *key)
         return dev ? &dev->ifindex : 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;
+}
+
 static void dev_map_flush_old(struct bpf_dtab_netdev *dev)
 {
         if (dev->dev->netdev_ops->ndo_xdp_xmit) {
@@ -422,6 +540,28 @@ static int dev_map_delete_elem(struct bpf_map *map, void *key)
         return 0;
 }
 
+static int dev_map_hash_delete_elem(struct bpf_map *map, void *key)
+{
+        struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
+        struct bpf_dtab_netdev *old_dev;
+        int k = *(u32 *)key;
+        unsigned long flags;
+        int ret = -ENOENT;
+
+        spin_lock_irqsave(&dtab->index_lock, flags);
+
+        old_dev = __dev_map_hash_lookup_elem(map, k);
+        if (old_dev) {
+                dtab->items--;
+                hlist_del_init_rcu(&old_dev->index_hlist);
+                call_rcu(&old_dev->rcu, __dev_map_entry_free);
+                ret = 0;
+        }
+        spin_unlock_irqrestore(&dtab->index_lock, flags);
+
+        return ret;
+}
+
 static struct bpf_dtab_netdev *__dev_map_alloc_node(struct net *net,
                                                     struct bpf_dtab *dtab,
                                                     u32 ifindex,
@@ -502,6 +642,56 @@ static int dev_map_update_elem(struct bpf_map *map, void *key, void *value,
                                      map, key, value, map_flags);
 }
 
+static int __dev_map_hash_update_elem(struct net *net, struct bpf_map *map,
+                                     void *key, void *value, u64 map_flags)
+{
+        struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
+        struct bpf_dtab_netdev *dev, *old_dev;
+        u32 ifindex = *(u32 *)value;
+        u32 idx = *(u32 *)key;
+        unsigned long flags;
+
+        if (unlikely(map_flags > BPF_EXIST || !ifindex))
+                return -EINVAL;
+
+        old_dev = __dev_map_hash_lookup_elem(map, idx);
+        if (old_dev && (map_flags & BPF_NOEXIST))
+                return -EEXIST;
+
+        dev = __dev_map_alloc_node(net, dtab, ifindex, idx);
+        if (IS_ERR(dev))
+                return PTR_ERR(dev);
+
+        spin_lock_irqsave(&dtab->index_lock, flags);
+
+        if (old_dev) {
+                hlist_del_rcu(&old_dev->index_hlist);
+        } else {
+                if (dtab->items >= dtab->map.max_entries) {
+                        spin_unlock_irqrestore(&dtab->index_lock, flags);
+                        call_rcu(&dev->rcu, __dev_map_entry_free);
+                        return -E2BIG;
+                }
+                dtab->items++;
+        }
+
+        hlist_add_head_rcu(&dev->index_hlist,
+                           dev_map_index_hash(dtab, idx));
+        spin_unlock_irqrestore(&dtab->index_lock, flags);
+
+        if (old_dev)
+                call_rcu(&old_dev->rcu, __dev_map_entry_free);
+
+        return 0;
+}
+
+static int dev_map_hash_update_elem(struct bpf_map *map, void *key, void *value,
+                                   u64 map_flags)
+{
+        return __dev_map_hash_update_elem(current->nsproxy->net_ns,
+                                         map, key, value, map_flags);
+}
+
 const struct bpf_map_ops dev_map_ops = {
         .map_alloc = dev_map_alloc,
         .map_free = dev_map_free,
@@ -512,6 +702,16 @@ const struct bpf_map_ops dev_map_ops = {
         .map_check_btf = map_check_no_btf,
 };
 
+const struct bpf_map_ops dev_map_hash_ops = {
+        .map_alloc = dev_map_alloc,
+        .map_free = dev_map_free,
+        .map_get_next_key = dev_map_hash_get_next_key,
+        .map_lookup_elem = dev_map_hash_lookup_elem,
+        .map_update_elem = dev_map_hash_update_elem,
+        .map_delete_elem = dev_map_hash_delete_elem,
+        .map_check_btf = map_check_no_btf,
+};
+
 static int dev_map_notification(struct notifier_block *notifier,
                                 ulong event, void *ptr)
 {