diff options
| -rw-r--r-- | net/core/filter.c | 93 |
1 files changed, 93 insertions, 0 deletions
diff --git a/net/core/filter.c b/net/core/filter.c index 8cae575ad437..6c8a075a3016 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -12214,6 +12214,98 @@ __bpf_kfunc int bpf_sock_ops_enable_tx_tstamp(struct bpf_sock_ops_kern *skops, return 0; } +/** + * bpf_xdp_pull_data() - Pull in non-linear xdp data. + * @x: &xdp_md associated with the XDP buffer + * @len: length of data to be made directly accessible in the linear part + * + * Pull in data in case the XDP buffer associated with @x is non-linear and + * not all @len are in the linear data area. + * + * Direct packet access allows reading and writing linear XDP data through + * packet pointers (i.e., &xdp_md->data + offsets). The amount of data which + * ends up in the linear part of the xdp_buff depends on the NIC and its + * configuration. When a frag-capable XDP program wants to directly access + * headers that may be in the non-linear area, call this kfunc to make sure + * the data is available in the linear area. Alternatively, use dynptr or + * bpf_xdp_{load,store}_bytes() to access data without pulling. + * + * This kfunc can also be used with bpf_xdp_adjust_head() to decapsulate + * headers in the non-linear data area. + * + * A call to this kfunc may reduce headroom. If there is not enough tailroom + * in the linear data area, metadata and data will be shifted down. + * + * A call to this kfunc is susceptible to change the buffer geometry. + * Therefore, at load time, all checks on pointers previously done by the + * verifier are invalidated and must be performed again, if the kfunc is used + * in combination with direct packet access. + * + * Return: + * * %0 - success + * * %-EINVAL - invalid len + */ +__bpf_kfunc int bpf_xdp_pull_data(struct xdp_md *x, u32 len) +{ + struct xdp_buff *xdp = (struct xdp_buff *)x; + struct skb_shared_info *sinfo = xdp_get_shared_info_from_buff(xdp); + int i, delta, shift, headroom, tailroom, n_frags_free = 0; + void *data_hard_end = xdp_data_hard_end(xdp); + int data_len = xdp->data_end - xdp->data; + void *start; + + if (len <= data_len) + return 0; + + if (unlikely(len > xdp_get_buff_len(xdp))) + return -EINVAL; + + start = xdp_data_meta_unsupported(xdp) ? xdp->data : xdp->data_meta; + + headroom = start - xdp->data_hard_start - sizeof(struct xdp_frame); + tailroom = data_hard_end - xdp->data_end; + + delta = len - data_len; + if (unlikely(delta > tailroom + headroom)) + return -EINVAL; + + shift = delta - tailroom; + if (shift > 0) { + memmove(start - shift, start, xdp->data_end - start); + + xdp->data_meta -= shift; + xdp->data -= shift; + xdp->data_end -= shift; + } + + for (i = 0; i < sinfo->nr_frags && delta; i++) { + skb_frag_t *frag = &sinfo->frags[i]; + u32 shrink = min_t(u32, delta, skb_frag_size(frag)); + + memcpy(xdp->data_end, skb_frag_address(frag), shrink); + + xdp->data_end += shrink; + sinfo->xdp_frags_size -= shrink; + delta -= shrink; + if (bpf_xdp_shrink_data(xdp, frag, shrink, false)) + n_frags_free++; + } + + if (unlikely(n_frags_free)) { + memmove(sinfo->frags, sinfo->frags + n_frags_free, + (sinfo->nr_frags - n_frags_free) * sizeof(skb_frag_t)); + + sinfo->nr_frags -= n_frags_free; + + if (!sinfo->nr_frags) { + xdp_buff_clear_frags_flag(xdp); + xdp_buff_clear_frag_pfmemalloc(xdp); + } + } + + return 0; +} + __bpf_kfunc_end_defs(); int bpf_dynptr_from_skb_rdonly(struct __sk_buff *skb, u64 flags, @@ -12241,6 +12333,7 @@ BTF_KFUNCS_END(bpf_kfunc_check_set_skb_meta) BTF_KFUNCS_START(bpf_kfunc_check_set_xdp) BTF_ID_FLAGS(func, bpf_dynptr_from_xdp) +BTF_ID_FLAGS(func, bpf_xdp_pull_data) BTF_KFUNCS_END(bpf_kfunc_check_set_xdp) BTF_KFUNCS_START(bpf_kfunc_check_set_sock_addr) |