> On May 31, 2019, at 11:57 AM, Jonathan Lemon <jonathan.le...@gmail.com> wrote:
>
> Currently, the AF_XDP code uses a separate map in order to
> determine if an xsk is bound to a queue. Instead of doing this,
> have bpf_map_lookup_elem() return the queue_id, as a way of
> indicating that there is a valid entry at the map index.
>
> Rearrange some xdp_sock members to eliminate structure holes.
>
> Signed-off-by: Jonathan Lemon <jonathan.le...@gmail.com>
> Acked-by: Björn Töpel <bjorn.to...@intel.com>
Acked-by: Song Liu <songliubrav...@fb.com>
> ---
> include/net/xdp_sock.h | 6 +++---
> kernel/bpf/verifier.c | 6 +++++-
> kernel/bpf/xskmap.c | 4 +++-
> .../selftests/bpf/verifier/prevent_map_lookup.c | 15 ---------------
> 4 files changed, 11 insertions(+), 20 deletions(-)
>
> diff --git a/include/net/xdp_sock.h b/include/net/xdp_sock.h
> index d074b6d60f8a..7d84b1da43d2 100644
> --- a/include/net/xdp_sock.h
> +++ b/include/net/xdp_sock.h
> @@ -57,12 +57,12 @@ struct xdp_sock {
> struct net_device *dev;
> struct xdp_umem *umem;
> struct list_head flush_node;
> - u16 queue_id;
> - struct xsk_queue *tx ____cacheline_aligned_in_smp;
> - struct list_head list;
> + u32 queue_id;
> bool zc;
> /* Protects multiple processes in the control path */
> struct mutex mutex;
> + struct xsk_queue *tx ____cacheline_aligned_in_smp;
> + struct list_head list;
> /* Mutual exclusion of NAPI TX thread and sendmsg error paths
> * in the SKB destructor callback.
> */
> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index 2778417e6e0c..91c730f85e92 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -2905,10 +2905,14 @@ static int check_map_func_compatibility(struct
> bpf_verifier_env *env,
> * appear.
> */
> case BPF_MAP_TYPE_CPUMAP:
> - case BPF_MAP_TYPE_XSKMAP:
> if (func_id != BPF_FUNC_redirect_map)
> goto error;
> break;
> + case BPF_MAP_TYPE_XSKMAP:
> + if (func_id != BPF_FUNC_redirect_map &&
> + func_id != BPF_FUNC_map_lookup_elem)
> + goto error;
> + break;
> case BPF_MAP_TYPE_ARRAY_OF_MAPS:
> case BPF_MAP_TYPE_HASH_OF_MAPS:
> if (func_id != BPF_FUNC_map_lookup_elem)
> diff --git a/kernel/bpf/xskmap.c b/kernel/bpf/xskmap.c
> index 686d244e798d..249b22089014 100644
> --- a/kernel/bpf/xskmap.c
> +++ b/kernel/bpf/xskmap.c
> @@ -154,7 +154,9 @@ void __xsk_map_flush(struct bpf_map *map)
>
> static void *xsk_map_lookup_elem(struct bpf_map *map, void *key)
> {
> - return ERR_PTR(-EOPNOTSUPP);
> + struct xdp_sock *xs = __xsk_map_lookup_elem(map, *(u32 *)key);
> +
> + return xs ? &xs->queue_id : NULL;
> }
>
> static int xsk_map_update_elem(struct bpf_map *map, void *key, void *value,
> diff --git a/tools/testing/selftests/bpf/verifier/prevent_map_lookup.c
> b/tools/testing/selftests/bpf/verifier/prevent_map_lookup.c
> index bbdba990fefb..da7a4b37cb98 100644
> --- a/tools/testing/selftests/bpf/verifier/prevent_map_lookup.c
> +++ b/tools/testing/selftests/bpf/verifier/prevent_map_lookup.c
> @@ -28,21 +28,6 @@
> .errstr = "cannot pass map_type 18 into func bpf_map_lookup_elem",
> .prog_type = BPF_PROG_TYPE_SOCK_OPS,
> },
> -{
> - "prevent map lookup in xskmap",
> - .insns = {
> - BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
> - BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
> - BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
> - BPF_LD_MAP_FD(BPF_REG_1, 0),
> - BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
> - BPF_EXIT_INSN(),
> - },
> - .fixup_map_xskmap = { 3 },
> - .result = REJECT,
> - .errstr = "cannot pass map_type 17 into func bpf_map_lookup_elem",
> - .prog_type = BPF_PROG_TYPE_XDP,
> -},
> {
> "prevent map lookup in stack trace",
> .insns = {
> --
> 2.17.1
>
