diff options
| -rw-r--r-- | include/linux/skbuff.h | 43 | ||||
| -rw-r--r-- | include/uapi/linux/bpf.h | 11 | ||||
| -rw-r--r-- | net/core/filter.c | 100 |
3 files changed, 150 insertions, 4 deletions
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 0f665cb26b50..7047448e8129 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -2295,7 +2295,7 @@ static inline int pskb_network_may_pull(struct sk_buff *skb, unsigned int len) int ___pskb_trim(struct sk_buff *skb, unsigned int len); -static inline void __skb_trim(struct sk_buff *skb, unsigned int len) +static inline void __skb_set_length(struct sk_buff *skb, unsigned int len) { if (unlikely(skb_is_nonlinear(skb))) { WARN_ON(1); @@ -2305,6 +2305,11 @@ static inline void __skb_trim(struct sk_buff *skb, unsigned int len) skb_set_tail_pointer(skb, len); } +static inline void __skb_trim(struct sk_buff *skb, unsigned int len) +{ + __skb_set_length(skb, len); +} + void skb_trim(struct sk_buff *skb, unsigned int len); static inline int __pskb_trim(struct sk_buff *skb, unsigned int len) @@ -2335,6 +2340,20 @@ static inline void pskb_trim_unique(struct sk_buff *skb, unsigned int len) BUG_ON(err); } +static inline int __skb_grow(struct sk_buff *skb, unsigned int len) +{ + unsigned int diff = len - skb->len; + + if (skb_tailroom(skb) < diff) { + int ret = pskb_expand_head(skb, 0, diff - skb_tailroom(skb), + GFP_ATOMIC); + if (ret) + return ret; + } + __skb_set_length(skb, len); + return 0; +} + /** * skb_orphan - orphan a buffer * @skb: buffer to orphan @@ -2938,6 +2957,21 @@ static inline int pskb_trim_rcsum(struct sk_buff *skb, unsigned int len) return __pskb_trim(skb, len); } +static inline int __skb_trim_rcsum(struct sk_buff *skb, unsigned int len) +{ + if (skb->ip_summed == CHECKSUM_COMPLETE) + skb->ip_summed = CHECKSUM_NONE; + __skb_trim(skb, len); + return 0; +} + +static inline int __skb_grow_rcsum(struct sk_buff *skb, unsigned int len) +{ + if (skb->ip_summed == CHECKSUM_COMPLETE) + skb->ip_summed = CHECKSUM_NONE; + return __skb_grow(skb, len); +} + #define skb_queue_walk(queue, skb) \ for (skb = (queue)->next; \ skb != (struct sk_buff *)(queue); \ @@ -3726,6 +3760,13 @@ static inline bool skb_is_gso_v6(const struct sk_buff *skb) return skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6; } +static inline void skb_gso_reset(struct sk_buff *skb) +{ + skb_shinfo(skb)->gso_size = 0; + skb_shinfo(skb)->gso_segs = 0; + skb_shinfo(skb)->gso_type = 0; +} + void __skb_warn_lro_forwarding(const struct sk_buff *skb); static inline bool skb_warn_if_lro(const struct sk_buff *skb) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 866d53c33298..e4c5a1baa993 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -386,6 +386,17 @@ enum bpf_func_id { */ BPF_FUNC_current_task_under_cgroup, + /** + * bpf_skb_change_tail(skb, len, flags) + * The helper will resize the skb to the given new size, + * to be used f.e. with control messages. + * @skb: pointer to skb + * @len: new skb length + * @flags: reserved + * Return: 0 on success or negative error + */ + BPF_FUNC_skb_change_tail, + __BPF_FUNC_MAX_ID, }; diff --git a/net/core/filter.c b/net/core/filter.c index 58b5e6dd25fe..abf546d96b6b 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -1350,14 +1350,18 @@ struct bpf_scratchpad { static DEFINE_PER_CPU(struct bpf_scratchpad, bpf_sp); +static inline int __bpf_try_make_writable(struct sk_buff *skb, + unsigned int write_len) +{ + return skb_ensure_writable(skb, write_len); +} + static inline int bpf_try_make_writable(struct sk_buff *skb, unsigned int write_len) { - int err; + int err = __bpf_try_make_writable(skb, write_len); - err = skb_ensure_writable(skb, write_len); bpf_compute_data_end(skb); - return err; } @@ -1992,6 +1996,92 @@ static const struct bpf_func_proto bpf_skb_change_type_proto = { .arg2_type = ARG_ANYTHING, }; +static u32 __bpf_skb_min_len(const struct sk_buff *skb) +{ + u32 min_len = skb_network_offset(skb); + + if (skb_transport_header_was_set(skb)) + min_len = skb_transport_offset(skb); + if (skb->ip_summed == CHECKSUM_PARTIAL) + min_len = skb_checksum_start_offset(skb) + + skb->csum_offset + sizeof(__sum16); + return min_len; +} + +static u32 __bpf_skb_max_len(const struct sk_buff *skb) +{ + return skb->dev ? skb->dev->mtu + skb->dev->hard_header_len : + 65536; +} + +static int bpf_skb_grow_rcsum(struct sk_buff *skb, unsigned int new_len) +{ + unsigned int old_len = skb->len; + int ret; + + ret = __skb_grow_rcsum(skb, new_len); + if (!ret) + memset(skb->data + old_len, 0, new_len - old_len); + return ret; +} + +static int bpf_skb_trim_rcsum(struct sk_buff *skb, unsigned int new_len) +{ + return __skb_trim_rcsum(skb, new_len); +} + +static u64 bpf_skb_change_tail(u64 r1, u64 r2, u64 flags, u64 r4, u64 r5) +{ + struct sk_buff *skb = (struct sk_buff *)(long) r1; + u32 max_len = __bpf_skb_max_len(skb); + u32 min_len = __bpf_skb_min_len(skb); + u32 new_len = (u32) r2; + int ret; + + if (unlikely(flags || new_len > max_len || new_len < min_len)) + return -EINVAL; + if (skb->encapsulation) + return -ENOTSUPP; + + /* The basic idea of this helper is that it's performing the + * needed work to either grow or trim an skb, and eBPF program + * rewrites the rest via helpers like bpf_skb_store_bytes(), + * bpf_lX_csum_replace() and others rather than passing a raw + * buffer here. This one is a slow path helper and intended + * for replies with control messages. + * + * Like in bpf_skb_change_proto(), we want to keep this rather + * minimal and without protocol specifics so that we are able + * to separate concerns as in bpf_skb_store_bytes() should only + * be the one responsible for writing buffers. + * + * It's really expected to be a slow path operation here for + * control message replies, so we're implicitly linearizing, + * uncloning and drop offloads from the skb by this. + */ + ret = __bpf_try_make_writable(skb, skb->len); + if (!ret) { + if (new_len > skb->len) + ret = bpf_skb_grow_rcsum(skb, new_len); + else if (new_len < skb->len) + ret = bpf_skb_trim_rcsum(skb, new_len); + if (!ret && skb_is_gso(skb)) + skb_gso_reset(skb); + } + + bpf_compute_data_end(skb); + return ret; +} + +static const struct bpf_func_proto bpf_skb_change_tail_proto = { + .func = bpf_skb_change_tail, + .gpl_only = false, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_CTX, + .arg2_type = ARG_ANYTHING, + .arg3_type = ARG_ANYTHING, +}; + bool bpf_helper_changes_skb_data(void *func) { if (func == bpf_skb_vlan_push) @@ -2002,6 +2092,8 @@ bool bpf_helper_changes_skb_data(void *func) return true; if (func == bpf_skb_change_proto) return true; + if (func == bpf_skb_change_tail) + return true; if (func == bpf_l3_csum_replace) return true; if (func == bpf_l4_csum_replace) @@ -2368,6 +2460,8 @@ tc_cls_act_func_proto(enum bpf_func_id func_id) return &bpf_skb_change_proto_proto; case BPF_FUNC_skb_change_type: return &bpf_skb_change_type_proto; + case BPF_FUNC_skb_change_tail: + return &bpf_skb_change_tail_proto; case BPF_FUNC_skb_get_tunnel_key: return &bpf_skb_get_tunnel_key_proto; case BPF_FUNC_skb_set_tunnel_key: |