// 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 <linux/local_lock.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;

local_lock_t bq_lock;

};

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_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_alloc_check(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;

if (attr->map_type == BPF_MAP_TYPE_DEVMAP_HASH) {

/* Hash table size must be power of 2; roundup_pow_of_two()

* can overflow into UB on 32-bit arches

*/

if (attr->max_entries > 1UL << 31)

return -EINVAL;

}

return 0;

}

static int dev_map_init_map(struct bpf_dtab *dtab, union bpf_attr *attr)

{

/* 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) {

/* Hash table size must be power of 2 */

dtab->n_buckets = roundup_pow_of_two(dtab->map.max_entries);

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);

u32 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_redirect_info->map is assigned in __bpf_xdp_redirect_map()

* during NAPI callback and cleared after the XDP redirect. There is no

* explicit RCU read section which protects bpf_redirect_info->map but

* local_bh_disable() also marks the beginning an RCU section. This

* makes the complete softirq callback RCU protected. Thus after

* following synchronize_rcu() there no bpf_redirect_info->map == map

* assignment.

*/

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 *tx_dev,

struct net_device *rx_dev)

{

struct xdp_txq_info txq = { .dev = tx_dev };

struct xdp_rxq_info rxq = { .dev = rx_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;

xdp.rxq = &rxq;

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(tx_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;

lockdep_assert_held(&bq->bq_lock);

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, bq->dev_rx);

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(struct list_head *flush_list)

{

struct xdp_dev_bulk_queue *bq, *tmp;

list_for_each_entry_safe(bq, tmp, flush_list, flush_node) {

local_lock_nested_bh(&bq->dev->xdp_bulkq->bq_lock);

bq_xmit_all(bq, XDP_XMIT_FLUSH);

bq->dev_rx = NULL;

bq->xdp_prog = NULL;

__list_del_clearprev(&bq->flush_node);

local_unlock_nested_bh(&bq->dev->xdp_bulkq->bq_lock);

}

}

/* 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. PREEMPT_RT relies on local_lock_nested_bh()

* to serialise access to the per-CPU bq.

*/

static void bq_enqueue(struct net_device *dev, struct xdp_frame *xdpf,

struct net_device *dev_rx, struct bpf_prog *xdp_prog)

{

struct xdp_dev_bulk_queue *bq;

local_lock_nested_bh(&dev->xdp_bulkq->bq_lock);

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) {

struct list_head *flush_list = bpf_net_ctx_get_dev_flush_list();

bq->dev_rx = dev_rx;

bq->xdp_prog = xdp_prog;

list_add(&bq->flush_node, flush_list);

}

bq->q[bq->count++] = xdpf;

local_unlock_nested_bh(&dev->xdp_bulkq->bq_lock);

}

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' elements.

* Returns the number of ifindexes added, or -EOVERFLOW if there are too

* many upper devices.

*/

static int get_upper_ifindexes(struct net_device *dev, int *indexes, int max)

{

struct net_device *upper;

struct list_head *iter;

int n = 0;

netdev_for_each_upper_dev_rcu(dev, upper, iter) {

if (n >= max)

return -EOVERFLOW;

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,

ARRAY_SIZE(excluded_devices) - 1);

if (num_excluded < 0)

return num_excluded;

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,

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;

}

}

}

/* 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,

const 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,

const 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,

const 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;

int num_excluded = 0;

unsigned int i;

int err;

if (exclude_ingress) {

num_excluded = get_upper_ifindexes(dev, excluded_devices,

ARRAY_SIZE(excluded_devices) - 1);

if (num_excluded < 0)

return num_excluded;

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_rcu(dst, head, index_hlist, rcu_read_lock_bh_held()) {

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;

u32 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;

u32 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,

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;