On Thu, Aug 16, 2018 at 9:44 AM, Petar Penkov <peterpenko...@gmail.com> wrote:
> From: Petar Penkov <ppen...@google.com>
>
> Adds a hook for programs of type BPF_PROG_TYPE_FLOW_DISSECTOR and
> attach type BPF_FLOW_DISSECTOR that is executed in the flow dissector
> path. The BPF program is kept as a global variable so it is
> accessible to all flow dissectors.
>
> Signed-off-by: Petar Penkov <ppen...@google.com>
> Signed-off-by: Willem de Bruijn <will...@google.com>
> ---
>  include/linux/bpf_types.h                 |   1 +
>  include/linux/skbuff.h                    |   7 +
>  include/net/flow_dissector.h              |  16 +++
>  include/uapi/linux/bpf.h                  |  14 +-
>  kernel/bpf/syscall.c                      |   8 ++
>  kernel/bpf/verifier.c                     |   2 +
>  net/core/filter.c                         | 157 ++++++++++++++++++++++
>  net/core/flow_dissector.c                 |  76 +++++++++++
>  tools/bpf/bpftool/prog.c                  |   1 +
>  tools/include/uapi/linux/bpf.h            |   5 +-
>  tools/lib/bpf/libbpf.c                    |   2 +
>  tools/testing/selftests/bpf/bpf_helpers.h |   3 +
>  12 files changed, 290 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/bpf_types.h b/include/linux/bpf_types.h
> index cd26c090e7c0..22083712dd18 100644
> --- a/include/linux/bpf_types.h
> +++ b/include/linux/bpf_types.h
> @@ -32,6 +32,7 @@ BPF_PROG_TYPE(BPF_PROG_TYPE_LIRC_MODE2, lirc_mode2)
>  #ifdef CONFIG_INET
>  BPF_PROG_TYPE(BPF_PROG_TYPE_SK_REUSEPORT, sk_reuseport)
>  #endif
> +BPF_PROG_TYPE(BPF_PROG_TYPE_FLOW_DISSECTOR, flow_dissector)
>
>  BPF_MAP_TYPE(BPF_MAP_TYPE_ARRAY, array_map_ops)
>  BPF_MAP_TYPE(BPF_MAP_TYPE_PERCPU_ARRAY, percpu_array_map_ops)
> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> index 17a13e4785fc..ce0e863f02a2 100644
> --- a/include/linux/skbuff.h
> +++ b/include/linux/skbuff.h
> @@ -243,6 +243,8 @@ struct scatterlist;
>  struct pipe_inode_info;
>  struct iov_iter;
>  struct napi_struct;
> +struct bpf_prog;
> +union bpf_attr;
>
>  #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
>  struct nf_conntrack {
> @@ -1192,6 +1194,11 @@ void skb_flow_dissector_init(struct flow_dissector 
> *flow_dissector,
>                              const struct flow_dissector_key *key,
>                              unsigned int key_count);
>
> +int skb_flow_dissector_bpf_prog_attach(const union bpf_attr *attr,
> +                                      struct bpf_prog *prog);
> +
> +int skb_flow_dissector_bpf_prog_detach(const union bpf_attr *attr);
> +
>  bool __skb_flow_dissect(const struct sk_buff *skb,
>                         struct flow_dissector *flow_dissector,
>                         void *target_container,
> diff --git a/include/net/flow_dissector.h b/include/net/flow_dissector.h
> index 6a4586dcdede..edb919d320c1 100644
> --- a/include/net/flow_dissector.h
> +++ b/include/net/flow_dissector.h
> @@ -270,6 +270,22 @@ __be32 flow_get_u32_dst(const struct flow_keys *flow);
>  extern struct flow_dissector flow_keys_dissector;
>  extern struct flow_dissector flow_keys_basic_dissector;
>
> +/* struct bpf_flow_dissect_cb:
> + *
> + * This struct is used to pass parameters to BPF programs of type
> + * BPF_PROG_TYPE_FLOW_DISSECTOR. Before such a program is run, the caller 
> sets
> + * the control block of the skb to be a struct of this type. The first field 
> is
> + * used to communicate the next header offset between the BPF programs and 
> the
> + * first value of it is passed from the kernel. The last two fields are used 
> for
> + * writing out flow keys.
> + */
> +struct bpf_flow_dissect_cb {
> +       u16 nhoff;
> +       u16 unused;
> +       void *target_container;
> +       struct flow_dissector *flow_dissector;
> +};
> +
>  /* struct flow_keys_digest:
>   *
>   * This structure is used to hold a digest of the full flow keys. This is a
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index 66917a4eba27..8bc0fdab685d 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -152,6 +152,7 @@ enum bpf_prog_type {
>         BPF_PROG_TYPE_LWT_SEG6LOCAL,
>         BPF_PROG_TYPE_LIRC_MODE2,
>         BPF_PROG_TYPE_SK_REUSEPORT,
> +       BPF_PROG_TYPE_FLOW_DISSECTOR,
>  };
>
>  enum bpf_attach_type {
> @@ -172,6 +173,7 @@ enum bpf_attach_type {
>         BPF_CGROUP_UDP4_SENDMSG,
>         BPF_CGROUP_UDP6_SENDMSG,
>         BPF_LIRC_MODE2,
> +       BPF_FLOW_DISSECTOR,
>         __MAX_BPF_ATTACH_TYPE
>  };
>
> @@ -2141,6 +2143,15 @@ union bpf_attr {
>   *             request in the skb.
>   *     Return
>   *             0 on success, or a negative error in case of failure.
> + *
> + * int bpf_flow_dissector_write_keys(const struct sk_buff *skb, const void 
> *from, u32 len, enum flow_dissector_key_id key_id)
> + *     Description
> + *             Try to write *len* bytes from the source pointer into the 
> offset
> + *             of the key with id *key_id*. If *len* is different from the
> + *             size of the key, an error is returned. If the key is not used,
> + *             this function exits with no effect and code 0.
> + *     Return
> + *             0 on success, negative error in case of failure.
>   */
>  #define __BPF_FUNC_MAPPER(FN)          \
>         FN(unspec),                     \
> @@ -2226,7 +2237,8 @@ union bpf_attr {
>         FN(get_current_cgroup_id),      \
>         FN(get_local_storage),          \
>         FN(sk_select_reuseport),        \
> -       FN(skb_ancestor_cgroup_id),
> +       FN(skb_ancestor_cgroup_id),     \
> +       FN(flow_dissector_write_keys),
>
>  /* integer value in 'imm' field of BPF_CALL instruction selects which helper
>   * function eBPF program intends to call
> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index 43727ed0d94a..a06568841a92 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -1616,6 +1616,9 @@ static int bpf_prog_attach(const union bpf_attr *attr)
>         case BPF_LIRC_MODE2:
>                 ptype = BPF_PROG_TYPE_LIRC_MODE2;
>                 break;
> +       case BPF_FLOW_DISSECTOR:
> +               ptype = BPF_PROG_TYPE_FLOW_DISSECTOR;
> +               break;
>         default:
>                 return -EINVAL;
>         }
> @@ -1637,6 +1640,9 @@ static int bpf_prog_attach(const union bpf_attr *attr)
>         case BPF_PROG_TYPE_LIRC_MODE2:
>                 ret = lirc_prog_attach(attr, prog);
>                 break;
> +       case BPF_PROG_TYPE_FLOW_DISSECTOR:
> +               ret = skb_flow_dissector_bpf_prog_attach(attr, prog);
> +               break;
>         default:
>                 ret = cgroup_bpf_prog_attach(attr, ptype, prog);
>         }
> @@ -1689,6 +1695,8 @@ static int bpf_prog_detach(const union bpf_attr *attr)
>                 return sockmap_get_from_fd(attr, BPF_PROG_TYPE_SK_SKB, NULL);
>         case BPF_LIRC_MODE2:
>                 return lirc_prog_detach(attr);
> +       case BPF_FLOW_DISSECTOR:
> +               return skb_flow_dissector_bpf_prog_detach(attr);
>         default:
>                 return -EINVAL;
>         }
> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index ca90679a7fe5..6d3f268fa8e0 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -1321,6 +1321,7 @@ static bool may_access_direct_pkt_data(struct 
> bpf_verifier_env *env,
>         case BPF_PROG_TYPE_LWT_XMIT:
>         case BPF_PROG_TYPE_SK_SKB:
>         case BPF_PROG_TYPE_SK_MSG:
> +       case BPF_PROG_TYPE_FLOW_DISSECTOR:
>                 if (meta)
>                         return meta->pkt_access;
>
> @@ -3976,6 +3977,7 @@ static bool may_access_skb(enum bpf_prog_type type)
>         case BPF_PROG_TYPE_SOCKET_FILTER:
>         case BPF_PROG_TYPE_SCHED_CLS:
>         case BPF_PROG_TYPE_SCHED_ACT:
> +       case BPF_PROG_TYPE_FLOW_DISSECTOR:
>                 return true;
>         default:
>                 return false;
> diff --git a/net/core/filter.c b/net/core/filter.c
> index fd423ce3da34..03d3037e6508 100644
> --- a/net/core/filter.c
> +++ b/net/core/filter.c
> @@ -4820,6 +4820,111 @@ bool bpf_helper_changes_pkt_data(void *func)
>         return false;
>  }
>
> +BPF_CALL_4(bpf_flow_dissector_write_keys, const struct sk_buff *, skb,
> +          const void *, from, u32, len, enum flow_dissector_key_id, key_id)
> +{
> +       struct bpf_flow_dissect_cb *cb;
> +       void *dest;
> +
> +       cb = (struct bpf_flow_dissect_cb *)bpf_skb_cb(skb);
> +
> +       /* Make sure the dissector actually uses the key. It is not an error 
> if
> +        * it does not, but we should not continue past this point in that 
> case
> +        */
> +       if (!dissector_uses_key(cb->flow_dissector, key_id))
> +               return 0;
> +
> +       /* Make sure the length is correct */
> +       switch (key_id) {
> +       case FLOW_DISSECTOR_KEY_CONTROL:
> +       case FLOW_DISSECTOR_KEY_ENC_CONTROL:
> +               if (len != sizeof(struct flow_dissector_key_control))
> +                       return -EINVAL;
> +               break;
> +       case FLOW_DISSECTOR_KEY_BASIC:
> +               if (len != sizeof(struct flow_dissector_key_basic))
> +                       return -EINVAL;
> +               break;
> +       case FLOW_DISSECTOR_KEY_IPV4_ADDRS:
> +       case FLOW_DISSECTOR_KEY_ENC_IPV4_ADDRS:
> +               if (len != sizeof(struct flow_dissector_key_ipv4_addrs))
> +                       return -EINVAL;
> +               break;
> +       case FLOW_DISSECTOR_KEY_IPV6_ADDRS:
> +       case FLOW_DISSECTOR_KEY_ENC_IPV6_ADDRS:
> +               if (len != sizeof(struct flow_dissector_key_ipv6_addrs))
> +                       return -EINVAL;
> +               break;
> +       case FLOW_DISSECTOR_KEY_ICMP:
> +               if (len != sizeof(struct flow_dissector_key_icmp))
> +                       return -EINVAL;
> +               break;
> +       case FLOW_DISSECTOR_KEY_PORTS:
> +       case FLOW_DISSECTOR_KEY_ENC_PORTS:
> +               if (len != sizeof(struct flow_dissector_key_ports))
> +                       return -EINVAL;
> +               break;
> +       case FLOW_DISSECTOR_KEY_ETH_ADDRS:
> +               if (len != sizeof(struct flow_dissector_key_eth_addrs))
> +                       return -EINVAL;
> +               break;
> +       case FLOW_DISSECTOR_KEY_TIPC:
> +               if (len != sizeof(struct flow_dissector_key_tipc))
> +                       return -EINVAL;
> +               break;
> +       case FLOW_DISSECTOR_KEY_ARP:
> +               if (len != sizeof(struct flow_dissector_key_arp))
> +                       return -EINVAL;
> +               break;
> +       case FLOW_DISSECTOR_KEY_VLAN:
> +       case FLOW_DISSECTOR_KEY_CVLAN:
> +               if (len != sizeof(struct flow_dissector_key_vlan))
> +                       return -EINVAL;
> +               break;
> +       case FLOW_DISSECTOR_KEY_FLOW_LABEL:
> +               if (len != sizeof(struct flow_dissector_key_tags))
> +                       return -EINVAL;
> +               break;
> +       case FLOW_DISSECTOR_KEY_GRE_KEYID:
> +       case FLOW_DISSECTOR_KEY_ENC_KEYID:
> +       case FLOW_DISSECTOR_KEY_MPLS_ENTROPY:
> +               if (len != sizeof(struct flow_dissector_key_keyid))
> +                       return -EINVAL;
> +               break;
> +       case FLOW_DISSECTOR_KEY_MPLS:
> +               if (len != sizeof(struct flow_dissector_key_mpls))
> +                       return -EINVAL;
> +               break;
> +       case FLOW_DISSECTOR_KEY_TCP:
> +               if (len != sizeof(struct flow_dissector_key_tcp))
> +                       return -EINVAL;
> +               break;
> +       case FLOW_DISSECTOR_KEY_IP:
> +       case FLOW_DISSECTOR_KEY_ENC_IP:
> +               if (len != sizeof(struct flow_dissector_key_ip))
> +                       return -EINVAL;
> +               break;
> +       default:
> +               return -EINVAL;
> +       }
> +
> +       dest = skb_flow_dissector_target(cb->flow_dissector, key_id,
> +                                        cb->target_container);
> +
> +       memcpy(dest, from, len);
> +       return 0;
> +}
> +
> +static const struct bpf_func_proto bpf_flow_dissector_write_keys_proto = {
> +       .func           = bpf_flow_dissector_write_keys,
> +       .gpl_only       = false,
> +       .ret_type       = RET_INTEGER,
> +       .arg1_type      = ARG_PTR_TO_CTX,
> +       .arg2_type      = ARG_PTR_TO_MEM,
> +       .arg3_type      = ARG_CONST_SIZE,
> +       .arg4_type      = ARG_ANYTHING,
> +};
> +
>  static const struct bpf_func_proto *
>  bpf_base_func_proto(enum bpf_func_id func_id)
>  {
> @@ -5100,6 +5205,19 @@ sk_skb_func_proto(enum bpf_func_id func_id, const 
> struct bpf_prog *prog)
>         }
>  }
>
> +static const struct bpf_func_proto *
> +flow_dissector_func_proto(enum bpf_func_id func_id, const struct bpf_prog 
> *prog)
> +{
> +       switch (func_id) {
> +       case BPF_FUNC_skb_load_bytes:
> +               return &bpf_skb_load_bytes_proto;
> +       case BPF_FUNC_flow_dissector_write_keys:
> +               return &bpf_flow_dissector_write_keys_proto;
> +       default:
> +               return bpf_base_func_proto(func_id);
> +       }
> +}
> +
>  static const struct bpf_func_proto *
>  lwt_out_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
>  {
> @@ -5738,6 +5856,35 @@ static bool sk_msg_is_valid_access(int off, int size,
>         return true;
>  }
>
> +static bool flow_dissector_is_valid_access(int off, int size,
> +                                          enum bpf_access_type type,
> +                                          const struct bpf_prog *prog,
> +                                          struct bpf_insn_access_aux *info)
> +{
> +       if (type == BPF_WRITE) {
> +               switch (off) {
> +               case bpf_ctx_range(struct __sk_buff, cb[0]):
> +                       break;
> +               default:
> +                       return false;
> +               }
> +       }
> +
> +       switch (off) {
> +       case bpf_ctx_range(struct __sk_buff, data):
> +               info->reg_type = PTR_TO_PACKET;
> +               break;
> +       case bpf_ctx_range(struct __sk_buff, data_end):
> +               info->reg_type = PTR_TO_PACKET_END;
> +               break;
> +       case bpf_ctx_range_till(struct __sk_buff, family, local_port):
> +       case bpf_ctx_range_till(struct __sk_buff, cb[1], cb[4]):
> +               return false;
> +       }
> +
> +       return bpf_skb_is_valid_access(off, size, type, prog, info);
> +}
> +
>  static u32 bpf_convert_ctx_access(enum bpf_access_type type,
>                                   const struct bpf_insn *si,
>                                   struct bpf_insn *insn_buf,
> @@ -6995,6 +7142,16 @@ const struct bpf_verifier_ops sk_msg_verifier_ops = {
>  const struct bpf_prog_ops sk_msg_prog_ops = {
>  };
>
> +const struct bpf_verifier_ops flow_dissector_verifier_ops = {
> +       .get_func_proto         = flow_dissector_func_proto,
> +       .is_valid_access        = flow_dissector_is_valid_access,
> +       .convert_ctx_access     = bpf_convert_ctx_access,
> +       .gen_ld_abs             = bpf_gen_ld_abs,
> +};
> +
> +const struct bpf_prog_ops flow_dissector_prog_ops = {
> +};
> +
>  int sk_detach_filter(struct sock *sk)
>  {
>         int ret = -ENOENT;
> diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
> index ce9eeeb7c024..767daa231f04 100644
> --- a/net/core/flow_dissector.c
> +++ b/net/core/flow_dissector.c
> @@ -25,6 +25,11 @@
>  #include <net/flow_dissector.h>
>  #include <scsi/fc/fc_fcoe.h>
>  #include <uapi/linux/batadv_packet.h>
> +#include <linux/bpf.h>
> +
> +/* BPF program accessible by all flow dissectors */
> +static struct bpf_prog __rcu *flow_dissector_prog;
> +static DEFINE_MUTEX(flow_dissector_mutex);
>
>  static void dissector_set_key(struct flow_dissector *flow_dissector,
>                               enum flow_dissector_key_id key_id)
> @@ -62,6 +67,40 @@ void skb_flow_dissector_init(struct flow_dissector 
> *flow_dissector,
>  }
>  EXPORT_SYMBOL(skb_flow_dissector_init);
>
> +int skb_flow_dissector_bpf_prog_attach(const union bpf_attr *attr,
> +                                      struct bpf_prog *prog)
> +{
> +       struct bpf_prog *attached;
> +
> +       mutex_lock(&flow_dissector_mutex);
> +       attached = rcu_dereference_protected(flow_dissector_prog,
> +                                            
> lockdep_is_held(&flow_dissector_mutex));
> +       if (attached) {
> +               /* Only one BPF program can be attached at a time */
> +               mutex_unlock(&flow_dissector_mutex);
> +               return -EEXIST;
> +       }
> +       rcu_assign_pointer(flow_dissector_prog, prog);
> +       mutex_unlock(&flow_dissector_mutex);
> +       return 0;
> +}
> +
> +int skb_flow_dissector_bpf_prog_detach(const union bpf_attr *attr)
> +{
> +       struct bpf_prog *attached;
> +
> +       mutex_lock(&flow_dissector_mutex);
> +       attached = rcu_dereference_protected(flow_dissector_prog,
> +                                            
> lockdep_is_held(&flow_dissector_mutex));
> +       if (!flow_dissector_prog) {
> +               mutex_unlock(&flow_dissector_mutex);
> +               return -EINVAL;
> +       }
> +       bpf_prog_put(attached);
> +       RCU_INIT_POINTER(flow_dissector_prog, NULL);
> +       mutex_unlock(&flow_dissector_mutex);
> +       return 0;
> +}
>  /**
>   * skb_flow_get_be16 - extract be16 entity
>   * @skb: sk_buff to extract from
> @@ -619,6 +658,7 @@ bool __skb_flow_dissect(const struct sk_buff *skb,
>         struct flow_dissector_key_vlan *key_vlan;
>         enum flow_dissect_ret fdret;
>         enum flow_dissector_key_id dissector_vlan = FLOW_DISSECTOR_KEY_MAX;
> +       struct bpf_prog *attached;
>         int num_hdrs = 0;
>         u8 ip_proto = 0;
>         bool ret;
> @@ -658,6 +698,42 @@ bool __skb_flow_dissect(const struct sk_buff *skb,
>                                               FLOW_DISSECTOR_KEY_BASIC,
>                                               target_container);
>
> +       rcu_read_lock();
> +       attached = rcu_dereference(flow_dissector_prog);
> +       if (attached) {
> +               /* Note that even though the const qualifier is discarded
> +                * throughout the execution of the BPF program, all 
> changes(the
> +                * control block) are reverted after the BPF program returns.
> +                * Therefore, __skb_flow_dissect does not alter the skb.
> +                */
> +               struct bpf_flow_dissect_cb *cb;
> +               u8 cb_saved[BPF_SKB_CB_LEN];
> +               u32 result;
> +
> +               cb = (struct bpf_flow_dissect_cb *)(bpf_skb_cb((struct 
> sk_buff *)skb));
> +
> +               /* Save Control Block */
> +               memcpy(cb_saved, cb, sizeof(cb_saved));
> +               memset(cb, 0, sizeof(cb_saved));
> +
> +               /* Pass parameters to the BPF program */
> +               cb->nhoff = nhoff;
> +               cb->target_container = target_container;
> +               cb->flow_dissector = flow_dissector;
> +
> +               bpf_compute_data_pointers((struct sk_buff *)skb);
> +               result = BPF_PROG_RUN(attached, skb);
> +
> +               /* Restore state */
> +               memcpy(cb, cb_saved, sizeof(cb_saved));
> +
> +               key_control->thoff = min_t(u16, key_control->thoff,
> +                                          skb ? skb->len : hlen);
> +               rcu_read_unlock();
> +               return result == BPF_OK;
> +       }

If the BPF program cannot handle certain protocol, shall we fall back
to the built-in logic? Otherwise, all BPF programs need to have some
code for all protocols.

Song

> +       rcu_read_unlock();
> +
>         if (dissector_uses_key(flow_dissector,
>                                FLOW_DISSECTOR_KEY_ETH_ADDRS)) {
>                 struct ethhdr *eth = eth_hdr(skb);
> diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
> index dce960d22106..b1cd3bc8db70 100644
> --- a/tools/bpf/bpftool/prog.c
> +++ b/tools/bpf/bpftool/prog.c
> @@ -74,6 +74,7 @@ static const char * const prog_type_name[] = {
>         [BPF_PROG_TYPE_RAW_TRACEPOINT]  = "raw_tracepoint",
>         [BPF_PROG_TYPE_CGROUP_SOCK_ADDR] = "cgroup_sock_addr",
>         [BPF_PROG_TYPE_LIRC_MODE2]      = "lirc_mode2",
> +       [BPF_PROG_TYPE_FLOW_DISSECTOR]  = "flow_dissector",
>  };
>
>  static void print_boot_time(__u64 nsecs, char *buf, unsigned int size)
> diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
> index 66917a4eba27..acd74a0dd063 100644
> --- a/tools/include/uapi/linux/bpf.h
> +++ b/tools/include/uapi/linux/bpf.h
> @@ -152,6 +152,7 @@ enum bpf_prog_type {
>         BPF_PROG_TYPE_LWT_SEG6LOCAL,
>         BPF_PROG_TYPE_LIRC_MODE2,
>         BPF_PROG_TYPE_SK_REUSEPORT,
> +       BPF_PROG_TYPE_FLOW_DISSECTOR,
>  };
>
>  enum bpf_attach_type {
> @@ -172,6 +173,7 @@ enum bpf_attach_type {
>         BPF_CGROUP_UDP4_SENDMSG,
>         BPF_CGROUP_UDP6_SENDMSG,
>         BPF_LIRC_MODE2,
> +       BPF_FLOW_DISSECTOR,
>         __MAX_BPF_ATTACH_TYPE
>  };
>
> @@ -2226,7 +2228,8 @@ union bpf_attr {
>         FN(get_current_cgroup_id),      \
>         FN(get_local_storage),          \
>         FN(sk_select_reuseport),        \
> -       FN(skb_ancestor_cgroup_id),
> +       FN(skb_ancestor_cgroup_id),     \
> +       FN(flow_dissector_write_keys),
>
>  /* integer value in 'imm' field of BPF_CALL instruction selects which helper
>   * function eBPF program intends to call
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index 2abd0f112627..0c749ce1b717 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -1502,6 +1502,7 @@ static bool bpf_prog_type__needs_kver(enum 
> bpf_prog_type type)
>         case BPF_PROG_TYPE_CGROUP_SOCK_ADDR:
>         case BPF_PROG_TYPE_LIRC_MODE2:
>         case BPF_PROG_TYPE_SK_REUSEPORT:
> +       case BPF_PROG_TYPE_FLOW_DISSECTOR:
>                 return false;
>         case BPF_PROG_TYPE_UNSPEC:
>         case BPF_PROG_TYPE_KPROBE:
> @@ -2121,6 +2122,7 @@ static const struct {
>         BPF_PROG_SEC("sk_skb",          BPF_PROG_TYPE_SK_SKB),
>         BPF_PROG_SEC("sk_msg",          BPF_PROG_TYPE_SK_MSG),
>         BPF_PROG_SEC("lirc_mode2",      BPF_PROG_TYPE_LIRC_MODE2),
> +       BPF_PROG_SEC("flow_dissector",  BPF_PROG_TYPE_FLOW_DISSECTOR),
>         BPF_SA_PROG_SEC("cgroup/bind4", BPF_CGROUP_INET4_BIND),
>         BPF_SA_PROG_SEC("cgroup/bind6", BPF_CGROUP_INET6_BIND),
>         BPF_SA_PROG_SEC("cgroup/connect4", BPF_CGROUP_INET4_CONNECT),
> diff --git a/tools/testing/selftests/bpf/bpf_helpers.h 
> b/tools/testing/selftests/bpf/bpf_helpers.h
> index e4be7730222d..4204c496a04f 100644
> --- a/tools/testing/selftests/bpf/bpf_helpers.h
> +++ b/tools/testing/selftests/bpf/bpf_helpers.h
> @@ -143,6 +143,9 @@ static unsigned long long (*bpf_skb_cgroup_id)(void *ctx) 
> =
>         (void *) BPF_FUNC_skb_cgroup_id;
>  static unsigned long long (*bpf_skb_ancestor_cgroup_id)(void *ctx, int 
> level) =
>         (void *) BPF_FUNC_skb_ancestor_cgroup_id;
> +static int (*bpf_flow_dissector_write_keys)(void *ctx, void *src, int len,
> +                                           int key) =
> +       (void *) BPF_FUNC_flow_dissector_write_keys;
>
>  /* llvm builtin functions that eBPF C program may use to
>   * emit BPF_LD_ABS and BPF_LD_IND instructions
> --
> 2.18.0.865.gffc8e1a3cd6-goog
>

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