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-rw-r--r--tools/testing/selftests/bpf/progs/test_seg6_loop.c260
1 files changed, 260 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/progs/test_seg6_loop.c b/tools/testing/selftests/bpf/progs/test_seg6_loop.c
new file mode 100644
index 000000000..a7278f064
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_seg6_loop.c
@@ -0,0 +1,260 @@
+#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
+ // workaround: define induction variable "i" as "long" instead
+ // of "int" to prevent alu32 sub-register spilling.
+ #pragma clang loop unroll(disable)
+ 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";