diff options
Diffstat (limited to 'tools/testing/selftests/bpf/progs/test_lwt_seg6local.c')
| -rw-r--r-- | tools/testing/selftests/bpf/progs/test_lwt_seg6local.c | 426 |
1 files changed, 426 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/progs/test_lwt_seg6local.c b/tools/testing/selftests/bpf/progs/test_lwt_seg6local.c new file mode 100644 index 000000000..48ff2b2ad --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_lwt_seg6local.c @@ -0,0 +1,426 @@ +#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> + +/* 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 + #pragma clang loop unroll(full) + for (int i = 0; i < 10; 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); +} + +static __always_inline +int delete_tlv(struct __sk_buff *skb, struct ip6_srh_t *srh, + uint32_t tlv_off) +{ + uint32_t srh_off = (char *)srh - (char *)(long)skb->data; + uint8_t len_remaining, new_pad; + uint32_t partial_srh_len; + uint32_t pad_off = 0; + uint32_t pad_size = 0; + struct sr6_tlv_t tlv; + int err; + + tlv_off += srh_off; + + err = is_valid_tlv_boundary(skb, srh, &tlv_off, &pad_size, &pad_off); + if (err) + return err; + + err = bpf_skb_load_bytes(skb, tlv_off, &tlv, sizeof(tlv)); + if (err) + return err; + + err = bpf_lwt_seg6_adjust_srh(skb, tlv_off, -(sizeof(tlv) + tlv.len)); + if (err) + return err; + + pad_off -= sizeof(tlv) + tlv.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); +} + +static __always_inline +int has_egr_tlv(struct __sk_buff *skb, struct ip6_srh_t *srh) +{ + int tlv_offset = sizeof(struct ip6_t) + sizeof(struct ip6_srh_t) + + ((srh->first_segment + 1) << 4); + struct sr6_tlv_t tlv; + + if (bpf_skb_load_bytes(skb, tlv_offset, &tlv, sizeof(struct sr6_tlv_t))) + return 0; + + if (tlv.type == SR6_TLV_EGRESS && tlv.len == 18) { + struct ip6_addr_t egr_addr; + + if (bpf_skb_load_bytes(skb, tlv_offset + 4, &egr_addr, 16)) + return 0; + + // check if egress TLV value is correct + if (bpf_be64_to_cpu(egr_addr.hi) == 0xfd00000000000000 && + bpf_be64_to_cpu(egr_addr.lo) == 0x4) + return 1; + } + + return 0; +} + +// This function will push a SRH with segments fd00::1, fd00::2, fd00::3, +// fd00::4 +SEC("encap_srh") +int __encap_srh(struct __sk_buff *skb) +{ + unsigned long long hi = 0xfd00000000000000; + struct ip6_addr_t *seg; + struct ip6_srh_t *srh; + char srh_buf[72]; // room for 4 segments + int err; + + srh = (struct ip6_srh_t *)srh_buf; + srh->nexthdr = 0; + srh->hdrlen = 8; + srh->type = 4; + srh->segments_left = 3; + srh->first_segment = 3; + srh->flags = 0; + srh->tag = 0; + + seg = (struct ip6_addr_t *)((char *)srh + sizeof(*srh)); + + #pragma clang loop unroll(full) + for (unsigned long long lo = 0; lo < 4; lo++) { + seg->lo = bpf_cpu_to_be64(4 - lo); + seg->hi = bpf_cpu_to_be64(hi); + seg = (struct ip6_addr_t *)((char *)seg + sizeof(*seg)); + } + + err = bpf_lwt_push_encap(skb, 0, (void *)srh, sizeof(srh_buf)); + if (err) + return BPF_DROP; + + return BPF_REDIRECT; +} + +// Add an Egress TLV fc00::4, add the flag A, +// and apply End.X action to fc42::1 +SEC("add_egr_x") +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; +} + +// Pop the Egress TLV, reset the flags, change the tag 2442 and finally do a +// simple End action +SEC("pop_egr") +int __pop_egr(struct __sk_buff *skb) +{ + struct ip6_srh_t *srh = get_srh(skb); + uint16_t new_tag = bpf_htons(2442); + uint8_t new_flags = 0; + int err, offset; + + if (srh == NULL) + return BPF_DROP; + + if (srh->flags != SR6_FLAG_ALERT) + return BPF_DROP; + + if (srh->hdrlen != 11) // 4 segments + Egress TLV + Padding TLV + return BPF_DROP; + + if (!has_egr_tlv(skb, srh)) + return BPF_DROP; + + err = delete_tlv(skb, srh, 8 + (srh->first_segment + 1) * 16); + if (err) + return BPF_DROP; + + offset = sizeof(struct ip6_t) + offsetof(struct ip6_srh_t, flags); + if (bpf_lwt_seg6_store_bytes(skb, offset, (void *)&new_flags, + sizeof(new_flags))) + return BPF_DROP; + + offset = sizeof(struct ip6_t) + offsetof(struct ip6_srh_t, tag); + if (bpf_lwt_seg6_store_bytes(skb, offset, (void *)&new_tag, + sizeof(new_tag))) + return BPF_DROP; + + return BPF_OK; +} + +// Inspect if the Egress TLV and flag have been removed, if the tag is correct, +// then apply a End.T action to reach the last segment +SEC("inspect_t") +int __inspect_t(struct __sk_buff *skb) +{ + struct ip6_srh_t *srh = get_srh(skb); + int table = 117; + int err; + + if (srh == NULL) + return BPF_DROP; + + if (srh->flags != 0) + return BPF_DROP; + + if (srh->tag != bpf_htons(2442)) + return BPF_DROP; + + if (srh->hdrlen != 8) // 4 segments + return BPF_DROP; + + err = bpf_lwt_seg6_action(skb, SEG6_LOCAL_ACTION_END_T, + (void *)&table, sizeof(table)); + + if (err) + return BPF_DROP; + + return BPF_REDIRECT; +} + +char __license[] SEC("license") = "GPL"; |