From e6a4750ffe9d701c4d55212b14b615e63571d235 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20T=C3=B6pel?= Date: Mon, 8 Mar 2021 12:29:06 +0100 Subject: bpf, xdp: Make bpf_redirect_map() a map operation MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Signed-off-by: Daniel Borkmann Acked-by: Jesper Dangaard Brouer Acked-by: Toke Høiland-Jørgensen Link: https://lore.kernel.org/bpf/20210308112907.559576-2-bjorn.topel@gmail.com --- include/linux/bpf.h | 26 ++++++-------------------- include/linux/filter.h | 27 +++++++++++++++++++++++++++ 2 files changed, 33 insertions(+), 20 deletions(-) (limited to 'include/linux') diff --git a/include/linux/bpf.h b/include/linux/bpf.h index c931bc97019d..a25730eaa148 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -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) { } diff --git a/include/linux/filter.h b/include/linux/filter.h index 3b00fc906ccd..008691fd3b58 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -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__ */ -- cgit v1.2.3 From ee75aef23afe6e88497151c127c13ed69f41aaa2 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20T=C3=B6pel?= Date: Mon, 8 Mar 2021 12:29:07 +0100 Subject: bpf, xdp: Restructure redirect actions MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The XDP_REDIRECT implementations for maps and non-maps are fairly similar, but obviously need to take different code paths depending on if the target is using a map or not. Today, the redirect targets for XDP either uses a map, or is based on ifindex. Here, the map type and id are added to bpf_redirect_info, instead of the actual map. Map type, map item/ifindex, and the map_id (if any) is passed to xdp_do_redirect(). For ifindex-based redirect, used by the bpf_redirect() XDP BFP helper, a special map type/id are used. Map type of UNSPEC together with map id equal to INT_MAX has the special meaning of an ifindex based redirect. Note that valid map ids are 1 inclusive, INT_MAX exclusive ([1,INT_MAX[). In addition to making the code easier to follow, using explicit type and id in bpf_redirect_info has a slight positive performance impact by avoiding a pointer indirection for the map type lookup, and instead use the cacheline for bpf_redirect_info. Since the actual map is not passed via bpf_redirect_info anymore, the map lookup is only done in the BPF helper. This means that the bpf_clear_redirect_map() function can be removed. The actual map item is RCU protected. The bpf_redirect_info flags member is not used by XDP, and not read/written any more. The map member is only written to when required/used, and not unconditionally. Signed-off-by: Björn Töpel Signed-off-by: Daniel Borkmann Reviewed-by: Maciej Fijalkowski Acked-by: Jesper Dangaard Brouer Acked-by: Toke Høiland-Jørgensen Link: https://lore.kernel.org/bpf/20210308112907.559576-3-bjorn.topel@gmail.com --- include/linux/filter.h | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) (limited to 'include/linux') diff --git a/include/linux/filter.h b/include/linux/filter.h index 008691fd3b58..b2b85b2cad8e 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -646,7 +646,8 @@ struct bpf_redirect_info { u32 flags; u32 tgt_index; void *tgt_value; - struct bpf_map *map; + u32 map_id; + enum bpf_map_type map_type; u32 kern_flags; struct bpf_nh_params nh; }; @@ -1488,13 +1489,14 @@ static __always_inline int __bpf_xdp_redirect_map(struct bpf_map *map, u32 ifind * performs multiple lookups, the last one always takes * precedence. */ - WRITE_ONCE(ri->map, NULL); + ri->map_id = INT_MAX; /* Valid map id idr range: [1,INT_MAX[ */ + ri->map_type = BPF_MAP_TYPE_UNSPEC; return flags; } - ri->flags = flags; ri->tgt_index = ifindex; - WRITE_ONCE(ri->map, map); + ri->map_id = map->id; + ri->map_type = map->map_type; return XDP_REDIRECT; } -- cgit v1.2.3