diff options
Diffstat (limited to 'net')
-rw-r--r-- | net/core/filter.c | 100 |
1 files changed, 97 insertions, 3 deletions
diff --git a/net/core/filter.c b/net/core/filter.c index 58b5e6d..abf546d 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: |