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bpf, xdp: Make bpf_redirect_map() a map operation

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Currently the bpf_redirect_map() implementation dispatches to the
correct map-lookup function via a switch-statement. To avoid the
dispatching, this change adds bpf_redirect_map() as a map
operation. Each map provides its bpf_redirect_map() version, and
correct function is automatically selected by the BPF verifier.

A nice side-effect of the code movement is that the map lookup
functions are now local to the map implementation files, which removes
one additional function call.

Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210308112907.559576-2-bjorn.topel@gmail.com
This commit is contained in:
Björn Töpel 2021-03-08 12:29:06 +01:00 committed by Daniel Borkmann
parent 11d39cfeec
commit e6a4750ffe
8 changed files with 82 additions and 82 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
include/linux/bpf.h
View File

@ -118,6 +118,9 @@ struct bpf_map_ops {
void *owner, u32 size);
struct bpf_local_storage __rcu ** (*map_owner_storage_ptr)(void *owner);
/* Misc helpers.*/
int (*map_redirect)(struct bpf_map *map, u32 ifindex, u64 flags);
/* map_meta_equal must be implemented for maps that can be
* used as an inner map. It is a runtime check to ensure
* an inner map can be inserted to an outer map.
@ -1450,9 +1453,9 @@ struct btf *bpf_get_btf_vmlinux(void);
/* Map specifics */
struct xdp_buff;
struct sk_buff;
struct bpf_dtab_netdev;
struct bpf_cpu_map_entry;
struct bpf_dtab_netdev *__dev_map_lookup_elem(struct bpf_map *map, u32 key);
struct bpf_dtab_netdev *__dev_map_hash_lookup_elem(struct bpf_map *map, u32 key);
void __dev_flush(void);
int dev_xdp_enqueue(struct net_device *dev, struct xdp_buff *xdp,
struct net_device *dev_rx);
@ -1462,7 +1465,6 @@ int dev_map_generic_redirect(struct bpf_dtab_netdev *dst, struct sk_buff *skb,
struct bpf_prog *xdp_prog);
bool dev_map_can_have_prog(struct bpf_map *map);
struct bpf_cpu_map_entry *__cpu_map_lookup_elem(struct bpf_map *map, u32 key);
void __cpu_map_flush(void);
int cpu_map_enqueue(struct bpf_cpu_map_entry *rcpu, struct xdp_buff *xdp,
struct net_device *dev_rx);
@ -1593,17 +1595,6 @@ static inline int bpf_obj_get_user(const char __user *pathname, int flags)
return -EOPNOTSUPP;
}
static inline struct net_device *__dev_map_lookup_elem(struct bpf_map *map,
u32 key)
{
return NULL;
}
static inline struct net_device *__dev_map_hash_lookup_elem(struct bpf_map *map,
u32 key)
{
return NULL;
}
static inline bool dev_map_can_have_prog(struct bpf_map *map)
{
return false;
@ -1615,6 +1606,7 @@ static inline void __dev_flush(void)
struct xdp_buff;
struct bpf_dtab_netdev;
struct bpf_cpu_map_entry;
static inline
int dev_xdp_enqueue(struct net_device *dev, struct xdp_buff *xdp,
@ -1639,12 +1631,6 @@ static inline int dev_map_generic_redirect(struct bpf_dtab_netdev *dst,
return 0;
}
static inline
struct bpf_cpu_map_entry *__cpu_map_lookup_elem(struct bpf_map *map, u32 key)
{
return NULL;
}
static inline void __cpu_map_flush(void)
{
}

27
include/linux/filter.h
View File

@ -1472,4 +1472,31 @@ static inline bool bpf_sk_lookup_run_v6(struct net *net, int protocol,
}
#endif /* IS_ENABLED(CONFIG_IPV6) */
static __always_inline int __bpf_xdp_redirect_map(struct bpf_map *map, u32 ifindex, u64 flags,
void *lookup_elem(struct bpf_map *map, u32 key))
{
struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info);
/* Lower bits of the flags are used as return code on lookup failure */
if (unlikely(flags > XDP_TX))
return XDP_ABORTED;
ri->tgt_value = lookup_elem(map, ifindex);
if (unlikely(!ri->tgt_value)) {
/* If the lookup fails we want to clear out the state in the
* redirect_info struct completely, so that if an eBPF program
* performs multiple lookups, the last one always takes
* precedence.
*/
WRITE_ONCE(ri->map, NULL);
return flags;
}
ri->flags = flags;
ri->tgt_index = ifindex;
WRITE_ONCE(ri->map, map);
return XDP_REDIRECT;
}
#endif /* __LINUX_FILTER_H__ */

19
include/net/xdp_sock.h
View File

@ -80,19 +80,6 @@ int xsk_generic_rcv(struct xdp_sock *xs, struct xdp_buff *xdp);
int __xsk_map_redirect(struct xdp_sock *xs, struct xdp_buff *xdp);
void __xsk_map_flush(void);
static inline struct xdp_sock *__xsk_map_lookup_elem(struct bpf_map *map,
u32 key)
{
struct xsk_map *m = container_of(map, struct xsk_map, map);
struct xdp_sock *xs;
if (key >= map->max_entries)
return NULL;
xs = READ_ONCE(m->xsk_map[key]);
return xs;
}
#else
static inline int xsk_generic_rcv(struct xdp_sock *xs, struct xdp_buff *xdp)
@ -109,12 +96,6 @@ static inline void __xsk_map_flush(void)
{
}
static inline struct xdp_sock *__xsk_map_lookup_elem(struct bpf_map *map,
u32 key)
{
return NULL;
}
#endif /* CONFIG_XDP_SOCKETS */
#endif /* _LINUX_XDP_SOCK_H */

8
kernel/bpf/cpumap.c
View File

@ -563,7 +563,7 @@ static void cpu_map_free(struct bpf_map *map)
kfree(cmap);
}
struct bpf_cpu_map_entry *__cpu_map_lookup_elem(struct bpf_map *map, u32 key)
static void *__cpu_map_lookup_elem(struct bpf_map *map, u32 key)
{
struct bpf_cpu_map *cmap = container_of(map, struct bpf_cpu_map, map);
struct bpf_cpu_map_entry *rcpu;
@ -600,6 +600,11 @@ static int cpu_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
return 0;
}
static int cpu_map_redirect(struct bpf_map *map, u32 ifindex, u64 flags)
{
return __bpf_xdp_redirect_map(map, ifindex, flags, __cpu_map_lookup_elem);
}
static int cpu_map_btf_id;
const struct bpf_map_ops cpu_map_ops = {
.map_meta_equal = bpf_map_meta_equal,
@ -612,6 +617,7 @@ const struct bpf_map_ops cpu_map_ops = {
.map_check_btf = map_check_no_btf,
.map_btf_name = "bpf_cpu_map",
.map_btf_id = &cpu_map_btf_id,
.map_redirect = cpu_map_redirect,
};
static void bq_flush_to_queue(struct xdp_bulk_queue *bq)

16
kernel/bpf/devmap.c
View File

@ -258,7 +258,7 @@ static int dev_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
return 0;
}
struct bpf_dtab_netdev *__dev_map_hash_lookup_elem(struct bpf_map *map, u32 key)
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);
@ -392,7 +392,7 @@ void __dev_flush(void)
* update happens in parallel here a dev_put wont happen until after reading the
* ifindex.
*/
struct bpf_dtab_netdev *__dev_map_lookup_elem(struct bpf_map *map, u32 key)
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;
@ -735,6 +735,16 @@ static int dev_map_hash_update_elem(struct bpf_map *map, void *key, void *value,
map, key, value, map_flags);
}
static int dev_map_redirect(struct bpf_map *map, u32 ifindex, u64 flags)
{
return __bpf_xdp_redirect_map(map, ifindex, flags, __dev_map_lookup_elem);
}
static int dev_hash_map_redirect(struct bpf_map *map, u32 ifindex, u64 flags)
{
return __bpf_xdp_redirect_map(map, ifindex, flags, __dev_map_hash_lookup_elem);
}
static int dev_map_btf_id;
const struct bpf_map_ops dev_map_ops = {
.map_meta_equal = bpf_map_meta_equal,
@ -747,6 +757,7 @@ const struct bpf_map_ops dev_map_ops = {
.map_check_btf = map_check_no_btf,
.map_btf_name = "bpf_dtab",
.map_btf_id = &dev_map_btf_id,
.map_redirect = dev_map_redirect,
};
static int dev_map_hash_map_btf_id;
@ -761,6 +772,7 @@ const struct bpf_map_ops dev_map_hash_ops = {
.map_check_btf = map_check_no_btf,
.map_btf_name = "bpf_dtab",
.map_btf_id = &dev_map_hash_map_btf_id,
.map_redirect = dev_hash_map_redirect,
};
static void dev_map_hash_remove_netdev(struct bpf_dtab *dtab,

13
kernel/bpf/verifier.c
View File

@ -5582,7 +5582,8 @@ record_func_map(struct bpf_verifier_env *env, struct bpf_call_arg_meta *meta,
func_id != BPF_FUNC_map_push_elem &&
func_id != BPF_FUNC_map_pop_elem &&
func_id != BPF_FUNC_map_peek_elem &&
func_id != BPF_FUNC_for_each_map_elem)
func_id != BPF_FUNC_for_each_map_elem &&
func_id != BPF_FUNC_redirect_map)
return 0;
if (map == NULL) {
@ -12017,7 +12018,8 @@ static int do_misc_fixups(struct bpf_verifier_env *env)
insn->imm == BPF_FUNC_map_delete_elem ||
insn->imm == BPF_FUNC_map_push_elem ||
insn->imm == BPF_FUNC_map_pop_elem ||
insn->imm == BPF_FUNC_map_peek_elem)) {
insn->imm == BPF_FUNC_map_peek_elem ||
insn->imm == BPF_FUNC_redirect_map)) {
aux = &env->insn_aux_data[i + delta];
if (bpf_map_ptr_poisoned(aux))
goto patch_call_imm;
@ -12059,6 +12061,9 @@ static int do_misc_fixups(struct bpf_verifier_env *env)
(int (*)(struct bpf_map *map, void *value))NULL));
BUILD_BUG_ON(!__same_type(ops->map_peek_elem,
(int (*)(struct bpf_map *map, void *value))NULL));
BUILD_BUG_ON(!__same_type(ops->map_redirect,
(int (*)(struct bpf_map *map, u32 ifindex, u64 flags))NULL));
patch_map_ops_generic:
switch (insn->imm) {
case BPF_FUNC_map_lookup_elem:
@ -12085,6 +12090,10 @@ patch_map_ops_generic:
insn->imm = BPF_CAST_CALL(ops->map_peek_elem) -
__bpf_call_base;
continue;
case BPF_FUNC_redirect_map:
insn->imm = BPF_CAST_CALL(ops->map_redirect) -
__bpf_call_base;
continue;
}
goto patch_call_imm;

39
net/core/filter.c
View File

@ -3943,22 +3943,6 @@ void xdp_do_flush(void)
}
EXPORT_SYMBOL_GPL(xdp_do_flush);
static inline void *__xdp_map_lookup_elem(struct bpf_map *map, u32 index)
{
switch (map->map_type) {
case BPF_MAP_TYPE_DEVMAP:
return __dev_map_lookup_elem(map, index);
case BPF_MAP_TYPE_DEVMAP_HASH:
return __dev_map_hash_lookup_elem(map, index);
case BPF_MAP_TYPE_CPUMAP:
return __cpu_map_lookup_elem(map, index);
case BPF_MAP_TYPE_XSKMAP:
return __xsk_map_lookup_elem(map, index);
default:
return NULL;
}
}
void bpf_clear_redirect_map(struct bpf_map *map)
{
struct bpf_redirect_info *ri;
@ -4112,28 +4096,7 @@ static const struct bpf_func_proto bpf_xdp_redirect_proto = {
BPF_CALL_3(bpf_xdp_redirect_map, struct bpf_map *, map, u32, ifindex,
u64, flags)
{
struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info);
/* Lower bits of the flags are used as return code on lookup failure */
if (unlikely(flags > XDP_TX))
return XDP_ABORTED;
ri->tgt_value = __xdp_map_lookup_elem(map, ifindex);
if (unlikely(!ri->tgt_value)) {
/* If the lookup fails we want to clear out the state in the
* redirect_info struct completely, so that if an eBPF program
* performs multiple lookups, the last one always takes
* precedence.
*/
WRITE_ONCE(ri->map, NULL);
return flags;
}
ri->flags = flags;
ri->tgt_index = ifindex;
WRITE_ONCE(ri->map, map);
return XDP_REDIRECT;
return map->ops->map_redirect(map, ifindex, flags);
}
static const struct bpf_func_proto bpf_xdp_redirect_map_proto = {

16
net/xdp/xskmap.c
View File

@ -125,6 +125,16 @@ static int xsk_map_gen_lookup(struct bpf_map *map, struct bpf_insn *insn_buf)
return insn - insn_buf;
}
static void *__xsk_map_lookup_elem(struct bpf_map *map, u32 key)
{
struct xsk_map *m = container_of(map, struct xsk_map, map);
if (key >= map->max_entries)
return NULL;
return READ_ONCE(m->xsk_map[key]);
}
static void *xsk_map_lookup_elem(struct bpf_map *map, void *key)
{
WARN_ON_ONCE(!rcu_read_lock_held());
@ -215,6 +225,11 @@ static int xsk_map_delete_elem(struct bpf_map *map, void *key)
return 0;
}
static int xsk_map_redirect(struct bpf_map *map, u32 ifindex, u64 flags)
{
return __bpf_xdp_redirect_map(map, ifindex, flags, __xsk_map_lookup_elem);
}
void xsk_map_try_sock_delete(struct xsk_map *map, struct xdp_sock *xs,
struct xdp_sock **map_entry)
{
@ -247,4 +262,5 @@ const struct bpf_map_ops xsk_map_ops = {
.map_check_btf = map_check_no_btf,
.map_btf_name = "xsk_map",
.map_btf_id = &xsk_map_btf_id,
.map_redirect = xsk_map_redirect,
};