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linux/kernel/bpf/devmap.c
Paolo Abeni 7b769adc26 bpf-next-for-netdev 
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Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

Daniel Borkmann says:

====================
pull-request: bpf-next 2024-07-08

The following pull-request contains BPF updates for your *net-next* tree.

We've added 102 non-merge commits during the last 28 day(s) which contain
a total of 127 files changed, 4606 insertions(+), 980 deletions(-).

The main changes are:

1) Support resilient split BTF which cuts down on duplication and makes BTF
   as compact as possible wrt BTF from modules, from Alan Maguire & Eduard Zingerman.

2) Add support for dumping kfunc prototypes from BTF which enables both detecting
   as well as dumping compilable prototypes for kfuncs, from Daniel Xu.

3) Batch of s390x BPF JIT improvements to add support for BPF arena and to implement
   support for BPF exceptions, from Ilya Leoshkevich.

4) Batch of riscv64 BPF JIT improvements in particular to add 12-argument support
   for BPF trampolines and to utilize bpf_prog_pack for the latter, from Pu Lehui.

5) Extend BPF test infrastructure to add a CHECKSUM_COMPLETE validation option
   for skbs and add coverage along with it, from Vadim Fedorenko.

6) Inline bpf_get_current_task/_btf() helpers in the arm64 BPF JIT which gives
   a small 1% performance improvement in micro-benchmarks, from Puranjay Mohan.

7) Extend the BPF verifier to track the delta between linked registers in order
   to better deal with recent LLVM code optimizations, from Alexei Starovoitov.

8) Fix bpf_wq_set_callback_impl() kfunc signature where the third argument should
   have been a pointer to the map value, from Benjamin Tissoires.

9) Extend BPF selftests to add regular expression support for test output matching
   and adjust some of the selftest when compiled under gcc, from Cupertino Miranda.

10) Simplify task_file_seq_get_next() and remove an unnecessary loop which always
    iterates exactly once anyway, from Dan Carpenter.

11) Add the capability to offload the netfilter flowtable in XDP layer through
    kfuncs, from Florian Westphal & Lorenzo Bianconi.

12) Various cleanups in networking helpers in BPF selftests to shave off a few
    lines of open-coded functions on client/server handling, from Geliang Tang.

13) Properly propagate prog->aux->tail_call_reachable out of BPF verifier, so
    that x86 JIT does not need to implement detection, from Leon Hwang.

14) Fix BPF verifier to add a missing check_func_arg_reg_off() to prevent an
    out-of-bounds memory access for dynpointers, from Matt Bobrowski.

15) Fix bpf_session_cookie() kfunc to return __u64 instead of long pointer as
    it might lead to problems on 32-bit archs, from Jiri Olsa.

16) Enhance traffic validation and dynamic batch size support in xsk selftests,
    from Tushar Vyavahare.

bpf-next-for-netdev

* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (102 commits)
  selftests/bpf: DENYLIST.aarch64: Remove fexit_sleep
  selftests/bpf: amend for wrong bpf_wq_set_callback_impl signature
  bpf: helpers: fix bpf_wq_set_callback_impl signature
  libbpf: Add NULL checks to bpf_object__{prev_map,next_map}
  selftests/bpf: Remove exceptions tests from DENYLIST.s390x
  s390/bpf: Implement exceptions
  s390/bpf: Change seen_reg to a mask
  bpf: Remove unnecessary loop in task_file_seq_get_next()
  riscv, bpf: Optimize stack usage of trampoline
  bpf, devmap: Add .map_alloc_check
  selftests/bpf: Remove arena tests from DENYLIST.s390x
  selftests/bpf: Add UAF tests for arena atomics
  selftests/bpf: Introduce __arena_global
  s390/bpf: Support arena atomics
  s390/bpf: Enable arena
  s390/bpf: Support address space cast instruction
  s390/bpf: Support BPF_PROBE_MEM32
  s390/bpf: Land on the next JITed instruction after exception
  s390/bpf: Introduce pre- and post- probe functions
  s390/bpf: Get rid of get_probe_mem_regno()
  ...
====================

Link: https://patch.msgid.link/20240708221438.10974-1-daniel@iogearbox.net
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2024-07-09 17:01:46 +02:00

1168 lines
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// 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_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);
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_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 *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(struct list_head *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 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) {
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;
}
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 (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_check = dev_map_alloc_check,
.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_check = dev_map_alloc_check,
.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)
{
/* 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);
return 0;
}
subsys_initcall(dev_map_init);
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