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-rw-r--r--kernel/bpf/devmap.c1160
1 files changed, 1160 insertions, 0 deletions
diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
new file mode 100644
index 0000000000..4d42f6ed6c
--- /dev/null
+++ b/kernel/bpf/devmap.c
@@ -0,0 +1,1160 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (c) 2017 Covalent IO, Inc. http://covalent.io
+ */
+
+/* Devmaps primary use is as a backend map for XDP BPF helper call
+ * bpf_redirect_map(). Because XDP is mostly concerned with performance we
+ * spent some effort to ensure the datapath with redirect maps does not use
+ * any locking. This is a quick note on the details.
+ *
+ * We have three possible paths to get into the devmap control plane bpf
+ * syscalls, bpf programs, and driver side xmit/flush operations. A bpf syscall
+ * will invoke an update, delete, or lookup operation. To ensure updates and
+ * deletes appear atomic from the datapath side xchg() is used to modify the
+ * netdev_map array. Then because the datapath does a lookup into the netdev_map
+ * array (read-only) from an RCU critical section we use call_rcu() to wait for
+ * an rcu grace period before free'ing the old data structures. This ensures the
+ * datapath always has a valid copy. However, the datapath does a "flush"
+ * operation that pushes any pending packets in the driver outside the RCU
+ * critical section. Each bpf_dtab_netdev tracks these pending operations using
+ * a per-cpu flush list. The bpf_dtab_netdev object will not be destroyed until
+ * this list is empty, indicating outstanding flush operations have completed.
+ *
+ * BPF syscalls may race with BPF program calls on any of the update, delete
+ * or lookup operations. As noted above the xchg() operation also keep the
+ * netdev_map consistent in this case. From the devmap side BPF programs
+ * calling into these operations are the same as multiple user space threads
+ * making system calls.
+ *
+ * Finally, any of the above may race with a netdev_unregister notifier. The
+ * unregister notifier must search for net devices in the map structure that
+ * contain a reference to the net device and remove them. This is a two step
+ * process (a) dereference the bpf_dtab_netdev object in netdev_map and (b)
+ * check to see if the ifindex is the same as the net_device being removed.
+ * When removing the dev a cmpxchg() is used to ensure the correct dev is
+ * removed, in the case of a concurrent update or delete operation it is
+ * possible that the initially referenced dev is no longer in the map. As the
+ * 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>
+#include <linux/filter.h>
+#include <trace/events/xdp.h>
+#include <linux/btf_ids.h>
+
+#define DEV_CREATE_FLAG_MASK \
+ (BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY)
+
+struct xdp_dev_bulk_queue {
+ struct xdp_frame *q[DEV_MAP_BULK_SIZE];
+ struct list_head flush_node;
+ struct net_device *dev;
+ struct net_device *dev_rx;
+ struct bpf_prog *xdp_prog;
+ unsigned int count;
+};
+
+struct bpf_dtab_netdev {
+ struct net_device *dev; /* must be first member, due to tracepoint */
+ struct hlist_node index_hlist;
+ struct bpf_prog *xdp_prog;
+ struct rcu_head rcu;
+ unsigned int idx;
+ struct bpf_devmap_val val;
+};
+
+struct bpf_dtab {
+ struct bpf_map map;
+ struct bpf_dtab_netdev __rcu **netdev_map; /* DEVMAP type only */
+ 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_PER_CPU(struct list_head, dev_flush_list);
+static DEFINE_SPINLOCK(dev_map_lock);
+static LIST_HEAD(dev_map_list);
+
+static struct hlist_head *dev_map_create_hash(unsigned int entries,
+ int numa_node)
+{
+ int i;
+ struct hlist_head *hash;
+
+ hash = bpf_map_area_alloc((u64) entries * sizeof(*hash), numa_node);
+ if (hash != NULL)
+ for (i = 0; i < entries; i++)
+ INIT_HLIST_HEAD(&hash[i]);
+
+ return hash;
+}
+
+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)];
+}
+
+static int dev_map_init_map(struct bpf_dtab *dtab, union bpf_attr *attr)
+{
+ u32 valsize = attr->value_size;
+
+ /* check sanity of attributes. 2 value sizes supported:
+ * 4 bytes: ifindex
+ * 8 bytes: ifindex + prog fd
+ */
+ if (attr->max_entries == 0 || attr->key_size != 4 ||
+ (valsize != offsetofend(struct bpf_devmap_val, ifindex) &&
+ valsize != offsetofend(struct bpf_devmap_val, bpf_prog.fd)) ||
+ attr->map_flags & ~DEV_CREATE_FLAG_MASK)
+ return -EINVAL;
+
+ /* Lookup returns a pointer straight to dev->ifindex, so make sure the
+ * verifier prevents writes from the BPF side
+ */
+ attr->map_flags |= BPF_F_RDONLY_PROG;
+
+
+ bpf_map_init_from_attr(&dtab->map, attr);
+
+ 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;
+ }
+
+ if (attr->map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
+ dtab->dev_index_head = dev_map_create_hash(dtab->n_buckets,
+ dtab->map.numa_node);
+ if (!dtab->dev_index_head)
+ return -ENOMEM;
+
+ spin_lock_init(&dtab->index_lock);
+ } else {
+ dtab->netdev_map = bpf_map_area_alloc((u64) dtab->map.max_entries *
+ sizeof(struct bpf_dtab_netdev *),
+ dtab->map.numa_node);
+ if (!dtab->netdev_map)
+ return -ENOMEM;
+ }
+
+ return 0;
+}
+
+static struct bpf_map *dev_map_alloc(union bpf_attr *attr)
+{
+ struct bpf_dtab *dtab;
+ int err;
+
+ dtab = bpf_map_area_alloc(sizeof(*dtab), NUMA_NO_NODE);
+ if (!dtab)
+ return ERR_PTR(-ENOMEM);
+
+ err = dev_map_init_map(dtab, attr);
+ if (err) {
+ bpf_map_area_free(dtab);
+ return ERR_PTR(err);
+ }
+
+ spin_lock(&dev_map_lock);
+ list_add_tail_rcu(&dtab->list, &dev_map_list);
+ spin_unlock(&dev_map_lock);
+
+ return &dtab->map;
+}
+
+static void dev_map_free(struct bpf_map *map)
+{
+ struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
+ int i;
+
+ /* At this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
+ * so the programs (can be more than one that used this map) were
+ * disconnected from events. The following synchronize_rcu() guarantees
+ * both rcu read critical sections complete and waits for
+ * preempt-disable regions (NAPI being the relevant context here) so we
+ * are certain there will be no further reads against the netdev_map and
+ * all flush operations are complete. Flush operations can only be done
+ * from NAPI context for this reason.
+ */
+
+ spin_lock(&dev_map_lock);
+ list_del_rcu(&dtab->list);
+ spin_unlock(&dev_map_lock);
+
+ bpf_clear_redirect_map(map);
+ synchronize_rcu();
+
+ /* Make sure prior __dev_map_entry_free() have completed. */
+ rcu_barrier();
+
+ if (dtab->map.map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
+ for (i = 0; i < dtab->n_buckets; i++) {
+ struct bpf_dtab_netdev *dev;
+ struct hlist_head *head;
+ struct hlist_node *next;
+
+ head = dev_map_index_hash(dtab, i);
+
+ hlist_for_each_entry_safe(dev, next, head, index_hlist) {
+ hlist_del_rcu(&dev->index_hlist);
+ if (dev->xdp_prog)
+ bpf_prog_put(dev->xdp_prog);
+ dev_put(dev->dev);
+ kfree(dev);
+ }
+ }
+
+ bpf_map_area_free(dtab->dev_index_head);
+ } else {
+ for (i = 0; i < dtab->map.max_entries; i++) {
+ struct bpf_dtab_netdev *dev;
+
+ dev = rcu_dereference_raw(dtab->netdev_map[i]);
+ if (!dev)
+ continue;
+
+ if (dev->xdp_prog)
+ bpf_prog_put(dev->xdp_prog);
+ dev_put(dev->dev);
+ kfree(dev);
+ }
+
+ bpf_map_area_free(dtab->netdev_map);
+ }
+
+ bpf_map_area_free(dtab);
+}
+
+static int dev_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
+{
+ struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
+ u32 index = key ? *(u32 *)key : U32_MAX;
+ u32 *next = next_key;
+
+ if (index >= dtab->map.max_entries) {
+ *next = 0;
+ return 0;
+ }
+
+ if (index == dtab->map.max_entries - 1)
+ return -ENOENT;
+ *next = index + 1;
+ return 0;
+}
+
+/* Elements are kept alive by RCU; either by rcu_read_lock() (from syscall) or
+ * by local_bh_disable() (from XDP calls inside NAPI). The
+ * rcu_read_lock_bh_held() below makes lockdep accept both.
+ */
+static void *__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,
+ lockdep_is_held(&dtab->index_lock))
+ 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 dev_map_bpf_prog_run(struct bpf_prog *xdp_prog,
+ struct xdp_frame **frames, int n,
+ struct net_device *dev)
+{
+ struct xdp_txq_info txq = { .dev = dev };
+ struct xdp_buff xdp;
+ int i, nframes = 0;
+
+ for (i = 0; i < n; i++) {
+ struct xdp_frame *xdpf = frames[i];
+ u32 act;
+ int err;
+
+ xdp_convert_frame_to_buff(xdpf, &xdp);
+ xdp.txq = &txq;
+
+ act = bpf_prog_run_xdp(xdp_prog, &xdp);
+ switch (act) {
+ case XDP_PASS:
+ err = xdp_update_frame_from_buff(&xdp, xdpf);
+ if (unlikely(err < 0))
+ xdp_return_frame_rx_napi(xdpf);
+ else
+ frames[nframes++] = xdpf;
+ break;
+ default:
+ bpf_warn_invalid_xdp_action(NULL, xdp_prog, act);
+ fallthrough;
+ case XDP_ABORTED:
+ trace_xdp_exception(dev, xdp_prog, act);
+ fallthrough;
+ case XDP_DROP:
+ xdp_return_frame_rx_napi(xdpf);
+ break;
+ }
+ }
+ return nframes; /* sent frames count */
+}
+
+static void bq_xmit_all(struct xdp_dev_bulk_queue *bq, u32 flags)
+{
+ struct net_device *dev = bq->dev;
+ unsigned int cnt = bq->count;
+ int sent = 0, err = 0;
+ int to_send = cnt;
+ int i;
+
+ if (unlikely(!cnt))
+ return;
+
+ for (i = 0; i < cnt; i++) {
+ struct xdp_frame *xdpf = bq->q[i];
+
+ prefetch(xdpf);
+ }
+
+ if (bq->xdp_prog) {
+ to_send = dev_map_bpf_prog_run(bq->xdp_prog, bq->q, cnt, dev);
+ if (!to_send)
+ goto out;
+ }
+
+ sent = dev->netdev_ops->ndo_xdp_xmit(dev, to_send, bq->q, flags);
+ if (sent < 0) {
+ /* If ndo_xdp_xmit fails with an errno, no frames have
+ * been xmit'ed.
+ */
+ err = sent;
+ sent = 0;
+ }
+
+ /* If not all frames have been transmitted, it is our
+ * responsibility to free them
+ */
+ for (i = sent; unlikely(i < to_send); i++)
+ xdp_return_frame_rx_napi(bq->q[i]);
+
+out:
+ bq->count = 0;
+ trace_xdp_devmap_xmit(bq->dev_rx, dev, sent, cnt - sent, err);
+}
+
+/* __dev_flush is called from xdp_do_flush() which _must_ be signalled from the
+ * driver before returning from its napi->poll() routine. See the comment above
+ * xdp_do_flush() in filter.c.
+ */
+void __dev_flush(void)
+{
+ struct list_head *flush_list = this_cpu_ptr(&dev_flush_list);
+ struct xdp_dev_bulk_queue *bq, *tmp;
+
+ list_for_each_entry_safe(bq, tmp, flush_list, flush_node) {
+ bq_xmit_all(bq, XDP_XMIT_FLUSH);
+ bq->dev_rx = NULL;
+ bq->xdp_prog = NULL;
+ __list_del_clearprev(&bq->flush_node);
+ }
+}
+
+/* Elements are kept alive by RCU; either by rcu_read_lock() (from syscall) or
+ * by local_bh_disable() (from XDP calls inside NAPI). The
+ * rcu_read_lock_bh_held() below makes lockdep accept both.
+ */
+static void *__dev_map_lookup_elem(struct bpf_map *map, u32 key)
+{
+ struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
+ struct bpf_dtab_netdev *obj;
+
+ if (key >= map->max_entries)
+ return NULL;
+
+ obj = rcu_dereference_check(dtab->netdev_map[key],
+ rcu_read_lock_bh_held());
+ return obj;
+}
+
+/* Runs in NAPI, i.e., softirq under local_bh_disable(). Thus, safe percpu
+ * variable access, and map elements stick around. See comment above
+ * xdp_do_flush() in filter.c.
+ */
+static void bq_enqueue(struct net_device *dev, struct xdp_frame *xdpf,
+ struct net_device *dev_rx, struct bpf_prog *xdp_prog)
+{
+ struct list_head *flush_list = this_cpu_ptr(&dev_flush_list);
+ struct xdp_dev_bulk_queue *bq = this_cpu_ptr(dev->xdp_bulkq);
+
+ if (unlikely(bq->count == DEV_MAP_BULK_SIZE))
+ bq_xmit_all(bq, 0);
+
+ /* Ingress dev_rx will be the same for all xdp_frame's in
+ * bulk_queue, because bq stored per-CPU and must be flushed
+ * from net_device drivers NAPI func end.
+ *
+ * Do the same with xdp_prog and flush_list since these fields
+ * are only ever modified together.
+ */
+ if (!bq->dev_rx) {
+ bq->dev_rx = dev_rx;
+ bq->xdp_prog = xdp_prog;
+ list_add(&bq->flush_node, flush_list);
+ }
+
+ bq->q[bq->count++] = xdpf;
+}
+
+static inline int __xdp_enqueue(struct net_device *dev, struct xdp_frame *xdpf,
+ struct net_device *dev_rx,
+ struct bpf_prog *xdp_prog)
+{
+ int err;
+
+ if (!(dev->xdp_features & NETDEV_XDP_ACT_NDO_XMIT))
+ return -EOPNOTSUPP;
+
+ if (unlikely(!(dev->xdp_features & NETDEV_XDP_ACT_NDO_XMIT_SG) &&
+ xdp_frame_has_frags(xdpf)))
+ return -EOPNOTSUPP;
+
+ err = xdp_ok_fwd_dev(dev, xdp_get_frame_len(xdpf));
+ if (unlikely(err))
+ return err;
+
+ bq_enqueue(dev, xdpf, dev_rx, xdp_prog);
+ return 0;
+}
+
+static u32 dev_map_bpf_prog_run_skb(struct sk_buff *skb, struct bpf_dtab_netdev *dst)
+{
+ struct xdp_txq_info txq = { .dev = dst->dev };
+ struct xdp_buff xdp;
+ u32 act;
+
+ if (!dst->xdp_prog)
+ return XDP_PASS;
+
+ __skb_pull(skb, skb->mac_len);
+ xdp.txq = &txq;
+
+ act = bpf_prog_run_generic_xdp(skb, &xdp, dst->xdp_prog);
+ switch (act) {
+ case XDP_PASS:
+ __skb_push(skb, skb->mac_len);
+ break;
+ default:
+ bpf_warn_invalid_xdp_action(NULL, dst->xdp_prog, act);
+ fallthrough;
+ case XDP_ABORTED:
+ trace_xdp_exception(dst->dev, dst->xdp_prog, act);
+ fallthrough;
+ case XDP_DROP:
+ kfree_skb(skb);
+ break;
+ }
+
+ return act;
+}
+
+int dev_xdp_enqueue(struct net_device *dev, struct xdp_frame *xdpf,
+ struct net_device *dev_rx)
+{
+ return __xdp_enqueue(dev, xdpf, dev_rx, NULL);
+}
+
+int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_frame *xdpf,
+ struct net_device *dev_rx)
+{
+ struct net_device *dev = dst->dev;
+
+ return __xdp_enqueue(dev, xdpf, dev_rx, dst->xdp_prog);
+}
+
+static bool is_valid_dst(struct bpf_dtab_netdev *obj, struct xdp_frame *xdpf)
+{
+ if (!obj)
+ return false;
+
+ if (!(obj->dev->xdp_features & NETDEV_XDP_ACT_NDO_XMIT))
+ return false;
+
+ if (unlikely(!(obj->dev->xdp_features & NETDEV_XDP_ACT_NDO_XMIT_SG) &&
+ xdp_frame_has_frags(xdpf)))
+ return false;
+
+ if (xdp_ok_fwd_dev(obj->dev, xdp_get_frame_len(xdpf)))
+ return false;
+
+ return true;
+}
+
+static int dev_map_enqueue_clone(struct bpf_dtab_netdev *obj,
+ struct net_device *dev_rx,
+ struct xdp_frame *xdpf)
+{
+ struct xdp_frame *nxdpf;
+
+ nxdpf = xdpf_clone(xdpf);
+ if (!nxdpf)
+ return -ENOMEM;
+
+ bq_enqueue(obj->dev, nxdpf, dev_rx, obj->xdp_prog);
+
+ return 0;
+}
+
+static inline bool is_ifindex_excluded(int *excluded, int num_excluded, int ifindex)
+{
+ while (num_excluded--) {
+ if (ifindex == excluded[num_excluded])
+ return true;
+ }
+ return false;
+}
+
+/* Get ifindex of each upper device. 'indexes' must be able to hold at
+ * least MAX_NEST_DEV elements.
+ * Returns the number of ifindexes added.
+ */
+static int get_upper_ifindexes(struct net_device *dev, int *indexes)
+{
+ struct net_device *upper;
+ struct list_head *iter;
+ int n = 0;
+
+ netdev_for_each_upper_dev_rcu(dev, upper, iter) {
+ indexes[n++] = upper->ifindex;
+ }
+ return n;
+}
+
+int dev_map_enqueue_multi(struct xdp_frame *xdpf, struct net_device *dev_rx,
+ struct bpf_map *map, bool exclude_ingress)
+{
+ struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
+ struct bpf_dtab_netdev *dst, *last_dst = NULL;
+ int excluded_devices[1+MAX_NEST_DEV];
+ struct hlist_head *head;
+ int num_excluded = 0;
+ unsigned int i;
+ int err;
+
+ if (exclude_ingress) {
+ num_excluded = get_upper_ifindexes(dev_rx, excluded_devices);
+ excluded_devices[num_excluded++] = dev_rx->ifindex;
+ }
+
+ if (map->map_type == BPF_MAP_TYPE_DEVMAP) {
+ for (i = 0; i < map->max_entries; i++) {
+ dst = rcu_dereference_check(dtab->netdev_map[i],
+ rcu_read_lock_bh_held());
+ if (!is_valid_dst(dst, xdpf))
+ continue;
+
+ if (is_ifindex_excluded(excluded_devices, num_excluded, dst->dev->ifindex))
+ continue;
+
+ /* we only need n-1 clones; last_dst enqueued below */
+ if (!last_dst) {
+ last_dst = dst;
+ continue;
+ }
+
+ err = dev_map_enqueue_clone(last_dst, dev_rx, xdpf);
+ if (err)
+ return err;
+
+ last_dst = dst;
+ }
+ } else { /* BPF_MAP_TYPE_DEVMAP_HASH */
+ for (i = 0; i < dtab->n_buckets; i++) {
+ head = dev_map_index_hash(dtab, i);
+ hlist_for_each_entry_rcu(dst, head, index_hlist,
+ lockdep_is_held(&dtab->index_lock)) {
+ if (!is_valid_dst(dst, xdpf))
+ continue;
+
+ if (is_ifindex_excluded(excluded_devices, num_excluded,
+ dst->dev->ifindex))
+ continue;
+
+ /* we only need n-1 clones; last_dst enqueued below */
+ if (!last_dst) {
+ last_dst = dst;
+ continue;
+ }
+
+ err = dev_map_enqueue_clone(last_dst, dev_rx, xdpf);
+ if (err)
+ return err;
+
+ last_dst = dst;
+ }
+ }
+ }
+
+ /* consume the last copy of the frame */
+ if (last_dst)
+ bq_enqueue(last_dst->dev, xdpf, dev_rx, last_dst->xdp_prog);
+ else
+ xdp_return_frame_rx_napi(xdpf); /* dtab is empty */
+
+ return 0;
+}
+
+int dev_map_generic_redirect(struct bpf_dtab_netdev *dst, struct sk_buff *skb,
+ struct bpf_prog *xdp_prog)
+{
+ int err;
+
+ err = xdp_ok_fwd_dev(dst->dev, skb->len);
+ if (unlikely(err))
+ return err;
+
+ /* Redirect has already succeeded semantically at this point, so we just
+ * return 0 even if packet is dropped. Helper below takes care of
+ * freeing skb.
+ */
+ if (dev_map_bpf_prog_run_skb(skb, dst) != XDP_PASS)
+ return 0;
+
+ skb->dev = dst->dev;
+ generic_xdp_tx(skb, xdp_prog);
+
+ return 0;
+}
+
+static int dev_map_redirect_clone(struct bpf_dtab_netdev *dst,
+ struct sk_buff *skb,
+ struct bpf_prog *xdp_prog)
+{
+ struct sk_buff *nskb;
+ int err;
+
+ nskb = skb_clone(skb, GFP_ATOMIC);
+ if (!nskb)
+ return -ENOMEM;
+
+ err = dev_map_generic_redirect(dst, nskb, xdp_prog);
+ if (unlikely(err)) {
+ consume_skb(nskb);
+ return err;
+ }
+
+ return 0;
+}
+
+int dev_map_redirect_multi(struct net_device *dev, struct sk_buff *skb,
+ struct bpf_prog *xdp_prog, struct bpf_map *map,
+ bool exclude_ingress)
+{
+ struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
+ struct bpf_dtab_netdev *dst, *last_dst = NULL;
+ int excluded_devices[1+MAX_NEST_DEV];
+ struct hlist_head *head;
+ struct hlist_node *next;
+ int num_excluded = 0;
+ unsigned int i;
+ int err;
+
+ if (exclude_ingress) {
+ num_excluded = get_upper_ifindexes(dev, excluded_devices);
+ excluded_devices[num_excluded++] = dev->ifindex;
+ }
+
+ if (map->map_type == BPF_MAP_TYPE_DEVMAP) {
+ for (i = 0; i < map->max_entries; i++) {
+ dst = rcu_dereference_check(dtab->netdev_map[i],
+ rcu_read_lock_bh_held());
+ if (!dst)
+ continue;
+
+ if (is_ifindex_excluded(excluded_devices, num_excluded, dst->dev->ifindex))
+ continue;
+
+ /* we only need n-1 clones; last_dst enqueued below */
+ if (!last_dst) {
+ last_dst = dst;
+ continue;
+ }
+
+ err = dev_map_redirect_clone(last_dst, skb, xdp_prog);
+ if (err)
+ return err;
+
+ last_dst = dst;
+
+ }
+ } else { /* BPF_MAP_TYPE_DEVMAP_HASH */
+ for (i = 0; i < dtab->n_buckets; i++) {
+ head = dev_map_index_hash(dtab, i);
+ hlist_for_each_entry_safe(dst, next, head, index_hlist) {
+ if (!dst)
+ continue;
+
+ if (is_ifindex_excluded(excluded_devices, num_excluded,
+ dst->dev->ifindex))
+ continue;
+
+ /* we only need n-1 clones; last_dst enqueued below */
+ if (!last_dst) {
+ last_dst = dst;
+ continue;
+ }
+
+ err = dev_map_redirect_clone(last_dst, skb, xdp_prog);
+ if (err)
+ return err;
+
+ last_dst = dst;
+ }
+ }
+ }
+
+ /* consume the first skb and return */
+ if (last_dst)
+ return dev_map_generic_redirect(last_dst, skb, xdp_prog);
+
+ /* dtab is empty */
+ consume_skb(skb);
+ return 0;
+}
+
+static void *dev_map_lookup_elem(struct bpf_map *map, void *key)
+{
+ struct bpf_dtab_netdev *obj = __dev_map_lookup_elem(map, *(u32 *)key);
+
+ 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);
+ return obj ? &obj->val : NULL;
+}
+
+static void __dev_map_entry_free(struct rcu_head *rcu)
+{
+ struct bpf_dtab_netdev *dev;
+
+ dev = container_of(rcu, struct bpf_dtab_netdev, rcu);
+ if (dev->xdp_prog)
+ bpf_prog_put(dev->xdp_prog);
+ dev_put(dev->dev);
+ kfree(dev);
+}
+
+static long dev_map_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;
+
+ if (k >= map->max_entries)
+ return -EINVAL;
+
+ old_dev = unrcu_pointer(xchg(&dtab->netdev_map[k], NULL));
+ if (old_dev) {
+ call_rcu(&old_dev->rcu, __dev_map_entry_free);
+ atomic_dec((atomic_t *)&dtab->items);
+ }
+ return 0;
+}
+
+static long 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,
+ struct bpf_devmap_val *val,
+ unsigned int idx)
+{
+ struct bpf_prog *prog = NULL;
+ struct bpf_dtab_netdev *dev;
+
+ dev = bpf_map_kmalloc_node(&dtab->map, sizeof(*dev),
+ GFP_NOWAIT | __GFP_NOWARN,
+ dtab->map.numa_node);
+ if (!dev)
+ return ERR_PTR(-ENOMEM);
+
+ dev->dev = dev_get_by_index(net, val->ifindex);
+ if (!dev->dev)
+ goto err_out;
+
+ if (val->bpf_prog.fd > 0) {
+ prog = bpf_prog_get_type_dev(val->bpf_prog.fd,
+ BPF_PROG_TYPE_XDP, false);
+ if (IS_ERR(prog))
+ goto err_put_dev;
+ if (prog->expected_attach_type != BPF_XDP_DEVMAP ||
+ !bpf_prog_map_compatible(&dtab->map, prog))
+ goto err_put_prog;
+ }
+
+ dev->idx = idx;
+ if (prog) {
+ dev->xdp_prog = prog;
+ dev->val.bpf_prog.id = prog->aux->id;
+ } else {
+ dev->xdp_prog = NULL;
+ dev->val.bpf_prog.id = 0;
+ }
+ dev->val.ifindex = val->ifindex;
+
+ return dev;
+err_put_prog:
+ bpf_prog_put(prog);
+err_put_dev:
+ dev_put(dev->dev);
+err_out:
+ kfree(dev);
+ return ERR_PTR(-EINVAL);
+}
+
+static long __dev_map_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;
+ struct bpf_devmap_val val = {};
+ u32 i = *(u32 *)key;
+
+ if (unlikely(map_flags > BPF_EXIST))
+ return -EINVAL;
+ if (unlikely(i >= dtab->map.max_entries))
+ return -E2BIG;
+ if (unlikely(map_flags == BPF_NOEXIST))
+ return -EEXIST;
+
+ /* already verified value_size <= sizeof val */
+ memcpy(&val, value, map->value_size);
+
+ if (!val.ifindex) {
+ dev = NULL;
+ /* can not specify fd if ifindex is 0 */
+ if (val.bpf_prog.fd > 0)
+ return -EINVAL;
+ } else {
+ dev = __dev_map_alloc_node(net, dtab, &val, i);
+ if (IS_ERR(dev))
+ return PTR_ERR(dev);
+ }
+
+ /* Use call_rcu() here to ensure rcu critical sections have completed
+ * Remembering the driver side flush operation will happen before the
+ * net device is removed.
+ */
+ old_dev = unrcu_pointer(xchg(&dtab->netdev_map[i], RCU_INITIALIZER(dev)));
+ if (old_dev)
+ call_rcu(&old_dev->rcu, __dev_map_entry_free);
+ else
+ atomic_inc((atomic_t *)&dtab->items);
+
+ return 0;
+}
+
+static long dev_map_update_elem(struct bpf_map *map, void *key, void *value,
+ u64 map_flags)
+{
+ return __dev_map_update_elem(current->nsproxy->net_ns,
+ map, key, value, map_flags);
+}
+
+static long __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;
+ struct bpf_devmap_val val = {};
+ u32 idx = *(u32 *)key;
+ unsigned long flags;
+ int err = -EEXIST;
+
+ /* 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);
+
+ old_dev = __dev_map_hash_lookup_elem(map, idx);
+ if (old_dev && (map_flags & BPF_NOEXIST))
+ goto out_err;
+
+ dev = __dev_map_alloc_node(net, dtab, &val, idx);
+ if (IS_ERR(dev)) {
+ err = PTR_ERR(dev);
+ goto out_err;
+ }
+
+ 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;
+
+out_err:
+ spin_unlock_irqrestore(&dtab->index_lock, flags);
+ return err;
+}
+
+static long 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);
+}
+
+static long dev_map_redirect(struct bpf_map *map, u64 ifindex, u64 flags)
+{
+ return __bpf_xdp_redirect_map(map, ifindex, flags,
+ BPF_F_BROADCAST | BPF_F_EXCLUDE_INGRESS,
+ __dev_map_lookup_elem);
+}
+
+static long dev_hash_map_redirect(struct bpf_map *map, u64 ifindex, u64 flags)
+{
+ return __bpf_xdp_redirect_map(map, ifindex, flags,
+ BPF_F_BROADCAST | BPF_F_EXCLUDE_INGRESS,
+ __dev_map_hash_lookup_elem);
+}
+
+static u64 dev_map_mem_usage(const struct bpf_map *map)
+{
+ struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
+ u64 usage = sizeof(struct bpf_dtab);
+
+ if (map->map_type == BPF_MAP_TYPE_DEVMAP_HASH)
+ usage += (u64)dtab->n_buckets * sizeof(struct hlist_head);
+ else
+ usage += (u64)map->max_entries * sizeof(struct bpf_dtab_netdev *);
+ usage += atomic_read((atomic_t *)&dtab->items) *
+ (u64)sizeof(struct bpf_dtab_netdev);
+ return usage;
+}
+
+BTF_ID_LIST_SINGLE(dev_map_btf_ids, struct, bpf_dtab)
+const struct bpf_map_ops dev_map_ops = {
+ .map_meta_equal = bpf_map_meta_equal,
+ .map_alloc = dev_map_alloc,
+ .map_free = dev_map_free,
+ .map_get_next_key = dev_map_get_next_key,
+ .map_lookup_elem = dev_map_lookup_elem,
+ .map_update_elem = dev_map_update_elem,
+ .map_delete_elem = dev_map_delete_elem,
+ .map_check_btf = map_check_no_btf,
+ .map_mem_usage = dev_map_mem_usage,
+ .map_btf_id = &dev_map_btf_ids[0],
+ .map_redirect = dev_map_redirect,
+};
+
+const struct bpf_map_ops dev_map_hash_ops = {
+ .map_meta_equal = bpf_map_meta_equal,
+ .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,
+ .map_mem_usage = dev_map_mem_usage,
+ .map_btf_id = &dev_map_btf_ids[0],
+ .map_redirect = dev_hash_map_redirect,
+};
+
+static void dev_map_hash_remove_netdev(struct bpf_dtab *dtab,
+ struct net_device *netdev)
+{
+ unsigned long flags;
+ u32 i;
+
+ spin_lock_irqsave(&dtab->index_lock, flags);
+ for (i = 0; i < dtab->n_buckets; i++) {
+ struct bpf_dtab_netdev *dev;
+ struct hlist_head *head;
+ struct hlist_node *next;
+
+ head = dev_map_index_hash(dtab, i);
+
+ hlist_for_each_entry_safe(dev, next, head, index_hlist) {
+ if (netdev != dev->dev)
+ continue;
+
+ dtab->items--;
+ hlist_del_rcu(&dev->index_hlist);
+ call_rcu(&dev->rcu, __dev_map_entry_free);
+ }
+ }
+ spin_unlock_irqrestore(&dtab->index_lock, flags);
+}
+
+static int dev_map_notification(struct notifier_block *notifier,
+ ulong event, void *ptr)
+{
+ struct net_device *netdev = netdev_notifier_info_to_dev(ptr);
+ struct bpf_dtab *dtab;
+ int i, cpu;
+
+ switch (event) {
+ case NETDEV_REGISTER:
+ if (!netdev->netdev_ops->ndo_xdp_xmit || netdev->xdp_bulkq)
+ break;
+
+ /* will be freed in free_netdev() */
+ netdev->xdp_bulkq = alloc_percpu(struct xdp_dev_bulk_queue);
+ if (!netdev->xdp_bulkq)
+ return NOTIFY_BAD;
+
+ for_each_possible_cpu(cpu)
+ per_cpu_ptr(netdev->xdp_bulkq, cpu)->dev = netdev;
+ break;
+ case NETDEV_UNREGISTER:
+ /* This rcu_read_lock/unlock pair is needed because
+ * dev_map_list is an RCU list AND to ensure a delete
+ * operation does not free a netdev_map entry while we
+ * are comparing it against the netdev being unregistered.
+ */
+ rcu_read_lock();
+ list_for_each_entry_rcu(dtab, &dev_map_list, list) {
+ if (dtab->map.map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
+ dev_map_hash_remove_netdev(dtab, netdev);
+ continue;
+ }
+
+ for (i = 0; i < dtab->map.max_entries; i++) {
+ struct bpf_dtab_netdev *dev, *odev;
+
+ dev = rcu_dereference(dtab->netdev_map[i]);
+ if (!dev || netdev != dev->dev)
+ continue;
+ odev = unrcu_pointer(cmpxchg(&dtab->netdev_map[i], RCU_INITIALIZER(dev), NULL));
+ if (dev == odev) {
+ call_rcu(&dev->rcu,
+ __dev_map_entry_free);
+ atomic_dec((atomic_t *)&dtab->items);
+ }
+ }
+ }
+ rcu_read_unlock();
+ break;
+ default:
+ break;
+ }
+ return NOTIFY_OK;
+}
+
+static struct notifier_block dev_map_notifier = {
+ .notifier_call = dev_map_notification,
+};
+
+static int __init dev_map_init(void)
+{
+ int cpu;
+
+ /* Assure tracepoint shadow struct _bpf_dtab_netdev is in sync */
+ BUILD_BUG_ON(offsetof(struct bpf_dtab_netdev, dev) !=
+ offsetof(struct _bpf_dtab_netdev, dev));
+ register_netdevice_notifier(&dev_map_notifier);
+
+ for_each_possible_cpu(cpu)
+ INIT_LIST_HEAD(&per_cpu(dev_flush_list, cpu));
+ return 0;
+}
+
+subsys_initcall(dev_map_init);
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-19 03:23:10 +0000