[PATCH v4 bpf-next 1/2] bpf: Allow bpf_map_lookup_elem() on an xskmap
From: Jonathan Lemon <hidden>
Date: 2019-06-03 16:38:58
Subsystem:
bpf [core], bpf [general] (safe dynamic programs and tools), bpf [selftests] (test runners & infrastructure), kernel selftest framework, networking [general], the rest, xdp sockets (af_xdp) · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Shuah Khan, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds, Magnus Karlsson, Maciej Fijalkowski
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 <redacted> Acked-by: Song Liu <redacted> Acked-by: Björn Töpel <redacted> --- 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