Author | Tokens | Token Proportion | Commits | Commit Proportion |
---|---|---|---|---|
Alexei Starovoitov | 1240 | 96.57% | 2 | 28.57% |
Jiri Benc | 33 | 2.57% | 1 | 14.29% |
Jose E. Marchesi | 4 | 0.31% | 1 | 14.29% |
Yonghong Song | 3 | 0.23% | 1 | 14.29% |
Ilya Leoshkevich | 2 | 0.16% | 1 | 14.29% |
Toke Höiland-Jörgensen | 2 | 0.16% | 1 | 14.29% |
Total | 1284 | 7 |
#include <stddef.h> #include <inttypes.h> #include <errno.h> #include <linux/seg6_local.h> #include <linux/bpf.h> #include <bpf/bpf_helpers.h> #include <bpf/bpf_endian.h> #include "bpf_compiler.h" /* Packet parsing state machine helpers. */ #define cursor_advance(_cursor, _len) \ ({ void *_tmp = _cursor; _cursor += _len; _tmp; }) #define SR6_FLAG_ALERT (1 << 4) #define BPF_PACKET_HEADER __attribute__((packed)) struct ip6_t { unsigned int ver:4; unsigned int priority:8; unsigned int flow_label:20; unsigned short payload_len; unsigned char next_header; unsigned char hop_limit; unsigned long long src_hi; unsigned long long src_lo; unsigned long long dst_hi; unsigned long long dst_lo; } BPF_PACKET_HEADER; struct ip6_addr_t { unsigned long long hi; unsigned long long lo; } BPF_PACKET_HEADER; struct ip6_srh_t { unsigned char nexthdr; unsigned char hdrlen; unsigned char type; unsigned char segments_left; unsigned char first_segment; unsigned char flags; unsigned short tag; struct ip6_addr_t segments[0]; } BPF_PACKET_HEADER; struct sr6_tlv_t { unsigned char type; unsigned char len; unsigned char value[0]; } BPF_PACKET_HEADER; static __always_inline struct ip6_srh_t *get_srh(struct __sk_buff *skb) { void *cursor, *data_end; struct ip6_srh_t *srh; struct ip6_t *ip; uint8_t *ipver; data_end = (void *)(long)skb->data_end; cursor = (void *)(long)skb->data; ipver = (uint8_t *)cursor; if ((void *)ipver + sizeof(*ipver) > data_end) return NULL; if ((*ipver >> 4) != 6) return NULL; ip = cursor_advance(cursor, sizeof(*ip)); if ((void *)ip + sizeof(*ip) > data_end) return NULL; if (ip->next_header != 43) return NULL; srh = cursor_advance(cursor, sizeof(*srh)); if ((void *)srh + sizeof(*srh) > data_end) return NULL; if (srh->type != 4) return NULL; return srh; } static __always_inline int update_tlv_pad(struct __sk_buff *skb, uint32_t new_pad, uint32_t old_pad, uint32_t pad_off) { int err; if (new_pad != old_pad) { err = bpf_lwt_seg6_adjust_srh(skb, pad_off, (int) new_pad - (int) old_pad); if (err) return err; } if (new_pad > 0) { char pad_tlv_buf[16] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}; struct sr6_tlv_t *pad_tlv = (struct sr6_tlv_t *) pad_tlv_buf; pad_tlv->type = SR6_TLV_PADDING; pad_tlv->len = new_pad - 2; err = bpf_lwt_seg6_store_bytes(skb, pad_off, (void *)pad_tlv_buf, new_pad); if (err) return err; } return 0; } static __always_inline int is_valid_tlv_boundary(struct __sk_buff *skb, struct ip6_srh_t *srh, uint32_t *tlv_off, uint32_t *pad_size, uint32_t *pad_off) { uint32_t srh_off, cur_off; int offset_valid = 0; int err; srh_off = (char *)srh - (char *)(long)skb->data; // cur_off = end of segments, start of possible TLVs cur_off = srh_off + sizeof(*srh) + sizeof(struct ip6_addr_t) * (srh->first_segment + 1); *pad_off = 0; // we can only go as far as ~10 TLVs due to the BPF max stack size // workaround: define induction variable "i" as "long" instead // of "int" to prevent alu32 sub-register spilling. __pragma_loop_no_unroll for (long i = 0; i < 100; i++) { struct sr6_tlv_t tlv; if (cur_off == *tlv_off) offset_valid = 1; if (cur_off >= srh_off + ((srh->hdrlen + 1) << 3)) break; err = bpf_skb_load_bytes(skb, cur_off, &tlv, sizeof(tlv)); if (err) return err; if (tlv.type == SR6_TLV_PADDING) { *pad_size = tlv.len + sizeof(tlv); *pad_off = cur_off; if (*tlv_off == srh_off) { *tlv_off = cur_off; offset_valid = 1; } break; } else if (tlv.type == SR6_TLV_HMAC) { break; } cur_off += sizeof(tlv) + tlv.len; } // we reached the padding or HMAC TLVs, or the end of the SRH if (*pad_off == 0) *pad_off = cur_off; if (*tlv_off == -1) *tlv_off = cur_off; else if (!offset_valid) return -EINVAL; return 0; } static __always_inline int add_tlv(struct __sk_buff *skb, struct ip6_srh_t *srh, uint32_t tlv_off, struct sr6_tlv_t *itlv, uint8_t tlv_size) { uint32_t srh_off = (char *)srh - (char *)(long)skb->data; uint8_t len_remaining, new_pad; uint32_t pad_off = 0; uint32_t pad_size = 0; uint32_t partial_srh_len; int err; if (tlv_off != -1) tlv_off += srh_off; if (itlv->type == SR6_TLV_PADDING || itlv->type == SR6_TLV_HMAC) return -EINVAL; err = is_valid_tlv_boundary(skb, srh, &tlv_off, &pad_size, &pad_off); if (err) return err; err = bpf_lwt_seg6_adjust_srh(skb, tlv_off, sizeof(*itlv) + itlv->len); if (err) return err; err = bpf_lwt_seg6_store_bytes(skb, tlv_off, (void *)itlv, tlv_size); if (err) return err; // the following can't be moved inside update_tlv_pad because the // bpf verifier has some issues with it pad_off += sizeof(*itlv) + itlv->len; partial_srh_len = pad_off - srh_off; len_remaining = partial_srh_len % 8; new_pad = 8 - len_remaining; if (new_pad == 1) // cannot pad for 1 byte only new_pad = 9; else if (new_pad == 8) new_pad = 0; return update_tlv_pad(skb, new_pad, pad_size, pad_off); } // Add an Egress TLV fc00::4, add the flag A, // and apply End.X action to fc42::1 SEC("lwt_seg6local") int __add_egr_x(struct __sk_buff *skb) { unsigned long long hi = 0xfc42000000000000; unsigned long long lo = 0x1; struct ip6_srh_t *srh = get_srh(skb); uint8_t new_flags = SR6_FLAG_ALERT; struct ip6_addr_t addr; int err, offset; if (srh == NULL) return BPF_DROP; uint8_t tlv[20] = {2, 18, 0, 0, 0xfd, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x4}; err = add_tlv(skb, srh, (srh->hdrlen+1) << 3, (struct sr6_tlv_t *)&tlv, 20); if (err) return BPF_DROP; offset = sizeof(struct ip6_t) + offsetof(struct ip6_srh_t, flags); err = bpf_lwt_seg6_store_bytes(skb, offset, (void *)&new_flags, sizeof(new_flags)); if (err) return BPF_DROP; addr.lo = bpf_cpu_to_be64(lo); addr.hi = bpf_cpu_to_be64(hi); err = bpf_lwt_seg6_action(skb, SEG6_LOCAL_ACTION_END_X, (void *)&addr, sizeof(addr)); if (err) return BPF_DROP; return BPF_REDIRECT; } char __license[] SEC("license") = "GPL";
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