[PATCH bpf-next v5 05/17] bpf: Introduce device-bound XDP programs

Stanislav Fomichev
2022-12-20T22:21:10Z

New flag BPF_F_XDP_DEV_BOUND_ONLY plus all the infra to have a way
to associate a netdev with a BPF program at load time.

Some existing 'offloaded' routines are renamed to 'dev_bound' for
consistency with the rest.

netdevsim checks are dropped in favor of generic check in dev_xdp_attach.

Cc: John Fastabend <john.fastabend@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Willem de Bruijn <willemb@google.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Anatoly Burakov <anatoly.burakov@intel.com>
Cc: Alexander Lobakin <alexandr.lobakin@intel.com>
Cc: Magnus Karlsson <magnus.karlsson@gmail.com>
Cc: Maryam Tahhan <mtahhan@redhat.com>
Cc: xdp-hints@xdp-project.net
Cc: netdev@vger.kernel.org
Signed-off-by: Stanislav Fomichev <sdf@google.com>
---
drivers/net/netdevsim/bpf.c | 4 --
include/linux/bpf.h | 24 ++++++--
include/uapi/linux/bpf.h | 5 ++
kernel/bpf/core.c | 4 +-
kernel/bpf/offload.c | 109 +++++++++++++++++++++++++--------
kernel/bpf/syscall.c | 9 +--
net/core/dev.c | 5 ++
tools/include/uapi/linux/bpf.h | 5 ++
8 files changed, 126 insertions(+), 39 deletions(-)

diff --git a/drivers/net/netdevsim/bpf.c b/drivers/net/netdevsim/bpf.c
index 50854265864d..f60eb97e3a62 100644
--- a/drivers/net/netdevsim/bpf.c
+++ b/drivers/net/netdevsim/bpf.c
@@ -315,10 +315,6 @@ nsim_setup_prog_hw_checks(struct netdevsim *ns, struct netdev_bpf *bpf)
NSIM_EA(bpf->extack, "xdpoffload of non-bound program");
return -EINVAL;
}
- if (!bpf_offload_dev_match(bpf->prog, ns->netdev)) {
- NSIM_EA(bpf->extack, "program bound to different dev");
- return -EINVAL;
- }

state = bpf->prog->aux->offload->dev_priv;
if (WARN_ON(strcmp(state->state, "xlated"))) {
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 630f259d0447..4c9649e69993 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1261,7 +1261,8 @@ struct bpf_prog_aux {
enum bpf_prog_type saved_dst_prog_type;
enum bpf_attach_type saved_dst_attach_type;
bool verifier_zext; /* Zero extensions has been inserted by verifier. */
- bool offload_requested;
+ bool dev_bound; /* Program is bound to the netdev. */
+ bool offload_requested; /* Program is bound and offloaded to the netdev. */
bool attach_btf_trace; /* true if attaching to BTF-enabled raw tp */
bool func_proto_unreliable;
bool sleepable;
@@ -2451,7 +2452,7 @@ void __bpf_free_used_maps(struct bpf_prog_aux *aux,
bool bpf_prog_get_ok(struct bpf_prog *, enum bpf_prog_type *, bool);

int bpf_prog_offload_compile(struct bpf_prog *prog);
-void bpf_prog_offload_destroy(struct bpf_prog *prog);
+void bpf_prog_dev_bound_destroy(struct bpf_prog *prog);
int bpf_prog_offload_info_fill(struct bpf_prog_info *info,
struct bpf_prog *prog);

@@ -2479,7 +2480,13 @@ bool bpf_offload_dev_match(struct bpf_prog *prog, struct net_device *netdev);
void unpriv_ebpf_notify(int new_state);

#if defined(CONFIG_NET) && defined(CONFIG_BPF_SYSCALL)
-int bpf_prog_offload_init(struct bpf_prog *prog, union bpf_attr *attr);
+int bpf_prog_dev_bound_init(struct bpf_prog *prog, union bpf_attr *attr);
+void bpf_dev_bound_netdev_unregister(struct net_device *dev);
+
+static inline bool bpf_prog_is_dev_bound(const struct bpf_prog_aux *aux)
+{
+ return aux->dev_bound;
+}

static inline bool bpf_prog_is_offloaded(const struct bpf_prog_aux *aux)
{
@@ -2507,12 +2514,21 @@ void sock_map_unhash(struct sock *sk);
void sock_map_destroy(struct sock *sk);
void sock_map_close(struct sock *sk, long timeout);
#else
-static inline int bpf_prog_offload_init(struct bpf_prog *prog,
+static inline int bpf_prog_dev_bound_init(struct bpf_prog *prog,
union bpf_attr *attr)
{
return -EOPNOTSUPP;
}

+static inline void bpf_dev_bound_netdev_unregister(struct net_device *dev)
+{
+}
+
+static inline bool bpf_prog_is_dev_bound(const struct bpf_prog_aux *aux)
+{
+ return false;
+}
+
static inline bool bpf_prog_is_offloaded(struct bpf_prog_aux *aux)
{
return false;
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index bc1a3d232ae4..d0b6ac896699 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -1156,6 +1156,11 @@ enum bpf_link_type {
*/
#define BPF_F_XDP_HAS_FRAGS (1U << 5)

+/* If BPF_F_XDP_DEV_BOUND_ONLY is used in BPF_PROG_LOAD command, the loaded
+ * program becomes device-bound but can access XDP metadata.
+ */
+#define BPF_F_XDP_DEV_BOUND_ONLY (1U << 6)
+
/* link_create.kprobe_multi.flags used in LINK_CREATE command for
* BPF_TRACE_KPROBE_MULTI attach type to create return probe.
*/
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index e9d64e26ef5b..bafcb7a3ae6f 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -2554,8 +2554,8 @@ static void bpf_prog_free_deferred(struct work_struct *work)
#endif
bpf_free_used_maps(aux);
bpf_free_used_btfs(aux);
- if (bpf_prog_is_offloaded(aux))
- bpf_prog_offload_destroy(aux->prog);
+ if (bpf_prog_is_dev_bound(aux))
+ bpf_prog_dev_bound_destroy(aux->prog);
#ifdef CONFIG_PERF_EVENTS
if (aux->prog->has_callchain_buf)
put_callchain_buffers();
diff --git a/kernel/bpf/offload.c b/kernel/bpf/offload.c
index deb06498da0b..e803824c1ddd 100644
--- a/kernel/bpf/offload.c
+++ b/kernel/bpf/offload.c
@@ -41,7 +41,7 @@ struct bpf_offload_dev {
struct bpf_offload_netdev {
struct rhash_head l;
struct net_device *netdev;
- struct bpf_offload_dev *offdev;
+ struct bpf_offload_dev *offdev; /* NULL when bound-only */
struct list_head progs;
struct list_head maps;
struct list_head offdev_netdevs;
@@ -89,19 +89,17 @@ static int __bpf_offload_dev_netdev_register(struct bpf_offload_dev *offdev,
INIT_LIST_HEAD(&ondev->progs);
INIT_LIST_HEAD(&ondev->maps);

- down_write(&bpf_devs_lock);
err = rhashtable_insert_fast(&offdevs, &ondev->l, offdevs_params);
if (err) {
netdev_warn(netdev, "failed to register for BPF offload\n");
- goto err_unlock_free;
+ goto err_free;
}

- list_add(&ondev->offdev_netdevs, &offdev->netdevs);
- up_write(&bpf_devs_lock);
+ if (offdev)
+ list_add(&ondev->offdev_netdevs, &offdev->netdevs);
return 0;

-err_unlock_free:
- up_write(&bpf_devs_lock);
+err_free:
kfree(ondev);
return err;
}
@@ -149,24 +147,26 @@ static void __bpf_map_offload_destroy(struct bpf_offloaded_map *offmap)
static void __bpf_offload_dev_netdev_unregister(struct bpf_offload_dev *offdev,
struct net_device *netdev)
{
- struct bpf_offload_netdev *ondev, *altdev;
+ struct bpf_offload_netdev *ondev, *altdev = NULL;
struct bpf_offloaded_map *offmap, *mtmp;
struct bpf_prog_offload *offload, *ptmp;

ASSERT_RTNL();

- down_write(&bpf_devs_lock);
ondev = rhashtable_lookup_fast(&offdevs, &netdev, offdevs_params);
if (WARN_ON(!ondev))
- goto unlock;
+ return;

WARN_ON(rhashtable_remove_fast(&offdevs, &ondev->l, offdevs_params));
- list_del(&ondev->offdev_netdevs);

/* Try to move the objects to another netdev of the device */
- altdev = list_first_entry_or_null(&offdev->netdevs,
- struct bpf_offload_netdev,
- offdev_netdevs);
+ if (offdev) {
+ list_del(&ondev->offdev_netdevs);
+ altdev = list_first_entry_or_null(&offdev->netdevs,
+ struct bpf_offload_netdev,
+ offdev_netdevs);
+ }
+
if (altdev) {
list_for_each_entry(offload, &ondev->progs, offloads)
offload->netdev = altdev->netdev;
@@ -185,11 +185,9 @@ static void __bpf_offload_dev_netdev_unregister(struct bpf_offload_dev *offdev,
WARN_ON(!list_empty(&ondev->progs));
WARN_ON(!list_empty(&ondev->maps));
kfree(ondev);
-unlock:
- up_write(&bpf_devs_lock);
}

-int bpf_prog_offload_init(struct bpf_prog *prog, union bpf_attr *attr)
+int bpf_prog_dev_bound_init(struct bpf_prog *prog, union bpf_attr *attr)
{
struct bpf_offload_netdev *ondev;
struct bpf_prog_offload *offload;
@@ -199,7 +197,7 @@ int bpf_prog_offload_init(struct bpf_prog *prog, union bpf_attr *attr)
attr->prog_type != BPF_PROG_TYPE_XDP)
return -EINVAL;

- if (attr->prog_flags)
+ if (attr->prog_flags & ~BPF_F_XDP_DEV_BOUND_ONLY)
return -EINVAL;

offload = kzalloc(sizeof(*offload), GFP_USER);
@@ -214,11 +212,23 @@ int bpf_prog_offload_init(struct bpf_prog *prog, union bpf_attr *attr)
if (err)
goto err_maybe_put;

+ prog->aux->offload_requested = !(attr->prog_flags & BPF_F_XDP_DEV_BOUND_ONLY);
+
down_write(&bpf_devs_lock);
ondev = bpf_offload_find_netdev(offload->netdev);
if (!ondev) {
- err = -EINVAL;
- goto err_unlock;
+ if (bpf_prog_is_offloaded(prog->aux)) {
+ err = -EINVAL;
+ goto err_unlock;
+ }
+
+ /* When only binding to the device, explicitly
+ * create an entry in the hashtable.
+ */
+ err = __bpf_offload_dev_netdev_register(NULL, offload->netdev);
+ if (err)
+ goto err_unlock;
+ ondev = bpf_offload_find_netdev(offload->netdev);
}
offload->offdev = ondev->offdev;
prog->aux->offload = offload;
@@ -321,12 +331,41 @@ bpf_prog_offload_remove_insns(struct bpf_verifier_env *env, u32 off, u32 cnt)
up_read(&bpf_devs_lock);
}

-void bpf_prog_offload_destroy(struct bpf_prog *prog)
+static void __bpf_prog_dev_bound_destroy(struct bpf_prog *prog)
+{
+ struct bpf_prog_offload *offload = prog->aux->offload;
+
+ if (offload->dev_state)
+ offload->offdev->ops->destroy(prog);
+
+ /* Make sure BPF_PROG_GET_NEXT_ID can't find this dead program */
+ bpf_prog_free_id(prog, true);
+
+ kfree(offload);
+ prog->aux->offload = NULL;
+}
+
+void bpf_prog_dev_bound_destroy(struct bpf_prog *prog)
{
+ struct bpf_offload_netdev *ondev;
+ struct net_device *netdev;
+
+ rtnl_lock();
down_write(&bpf_devs_lock);
- if (prog->aux->offload)
- __bpf_prog_offload_destroy(prog);
+ if (prog->aux->offload) {
+ list_del_init(&prog->aux->offload->offloads);
+
+ netdev = prog->aux->offload->netdev;
+ if (netdev) {
+ ondev = bpf_offload_find_netdev(netdev);
+ if (ondev && !ondev->offdev && list_empty(&ondev->progs))
+ __bpf_offload_dev_netdev_unregister(NULL, netdev);
+ }
+
+ __bpf_prog_dev_bound_destroy(prog);
+ }
up_write(&bpf_devs_lock);
+ rtnl_unlock();
}

static int bpf_prog_offload_translate(struct bpf_prog *prog)
@@ -621,7 +660,7 @@ static bool __bpf_offload_dev_match(struct bpf_prog *prog,
struct bpf_offload_netdev *ondev1, *ondev2;
struct bpf_prog_offload *offload;

- if (!bpf_prog_is_offloaded(prog->aux))
+ if (!bpf_prog_is_dev_bound(prog->aux))
return false;

offload = prog->aux->offload;
@@ -667,14 +706,21 @@ bool bpf_offload_prog_map_match(struct bpf_prog *prog, struct bpf_map *map)
int bpf_offload_dev_netdev_register(struct bpf_offload_dev *offdev,
struct net_device *netdev)
{
- return __bpf_offload_dev_netdev_register(offdev, netdev);
+ int err;
+
+ down_write(&bpf_devs_lock);
+ err = __bpf_offload_dev_netdev_register(offdev, netdev);
+ up_write(&bpf_devs_lock);
+ return err;
}
EXPORT_SYMBOL_GPL(bpf_offload_dev_netdev_register);

void bpf_offload_dev_netdev_unregister(struct bpf_offload_dev *offdev,
struct net_device *netdev)
{
+ down_write(&bpf_devs_lock);
__bpf_offload_dev_netdev_unregister(offdev, netdev);
+ up_write(&bpf_devs_lock);
}
EXPORT_SYMBOL_GPL(bpf_offload_dev_netdev_unregister);

@@ -708,6 +754,19 @@ void *bpf_offload_dev_priv(struct bpf_offload_dev *offdev)
}
EXPORT_SYMBOL_GPL(bpf_offload_dev_priv);

+void bpf_dev_bound_netdev_unregister(struct net_device *dev)
+{
+ struct bpf_offload_netdev *ondev;
+
+ ASSERT_RTNL();
+
+ down_write(&bpf_devs_lock);
+ ondev = bpf_offload_find_netdev(dev);
+ if (ondev && !ondev->offdev)
+ __bpf_offload_dev_netdev_unregister(NULL, ondev->netdev);
+ up_write(&bpf_devs_lock);
+}
+
static int __init bpf_offload_init(void)
{
return rhashtable_init(&offdevs, &offdevs_params);
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 13bc96035116..11c558be4992 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -2491,7 +2491,8 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr)
BPF_F_TEST_STATE_FREQ |
BPF_F_SLEEPABLE |
BPF_F_TEST_RND_HI32 |
- BPF_F_XDP_HAS_FRAGS))
+ BPF_F_XDP_HAS_FRAGS |
+ BPF_F_XDP_DEV_BOUND_ONLY))
return -EINVAL;

if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) &&
@@ -2575,7 +2576,7 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr)
prog->aux->attach_btf = attach_btf;
prog->aux->attach_btf_id = attr->attach_btf_id;
prog->aux->dst_prog = dst_prog;
- prog->aux->offload_requested = !!attr->prog_ifindex;
+ prog->aux->dev_bound = !!attr->prog_ifindex;
prog->aux->sleepable = attr->prog_flags & BPF_F_SLEEPABLE;
prog->aux->xdp_has_frags = attr->prog_flags & BPF_F_XDP_HAS_FRAGS;

@@ -2598,8 +2599,8 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr)
atomic64_set(&prog->aux->refcnt, 1);
prog->gpl_compatible = is_gpl ? 1 : 0;

- if (bpf_prog_is_offloaded(prog->aux)) {
- err = bpf_prog_offload_init(prog, attr);
+ if (bpf_prog_is_dev_bound(prog->aux)) {
+ err = bpf_prog_dev_bound_init(prog, attr);
if (err)
goto free_prog_sec;
}
diff --git a/net/core/dev.c b/net/core/dev.c
index 7d31c57ddd7e..573b819c219a 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -9228,6 +9228,10 @@ static int dev_xdp_attach(struct net_device *dev, struct netlink_ext_ack *extack
NL_SET_ERR_MSG(extack, "Using offloaded program without HW_MODE flag is not supported");
return -EINVAL;
}
+ if (bpf_prog_is_dev_bound(new_prog->aux) && !bpf_offload_dev_match(new_prog, dev)) {
+ NL_SET_ERR_MSG(extack, "Program bound to different device");
+ return -EINVAL;
+ }
if (new_prog->expected_attach_type == BPF_XDP_DEVMAP) {
NL_SET_ERR_MSG(extack, "BPF_XDP_DEVMAP programs can not be attached to a device");
return -EINVAL;
@@ -10830,6 +10834,7 @@ void unregister_netdevice_many_notify(struct list_head *head,
dev_shutdown(dev);

dev_xdp_uninstall(dev);
+ bpf_dev_bound_netdev_unregister(dev);

netdev_offload_xstats_disable_all(dev);

diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index bc1a3d232ae4..d0b6ac896699 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -1156,6 +1156,11 @@ enum bpf_link_type {
*/
#define BPF_F_XDP_HAS_FRAGS (1U << 5)

+/* If BPF_F_XDP_DEV_BOUND_ONLY is used in BPF_PROG_LOAD command, the loaded
+ * program becomes device-bound but can access XDP metadata.
+ */
+#define BPF_F_XDP_DEV_BOUND_ONLY (1U << 6)
+
/* link_create.kprobe_multi.flags used in LINK_CREATE command for
* BPF_TRACE_KPROBE_MULTI attach type to create return probe.
*/
--
2.39.0.314.g84b9a713c41-goog