From f7e9cb1ecb6d922584abff16db07930162c57155 Mon Sep 17 00:00:00 2001 From: John Fastabend Date: Wed, 18 Oct 2017 07:10:58 -0700 Subject: bpf: remove mark access for SK_SKB program types The skb->mark field is a union with reserved_tailroom which is used in the TCP code paths from stream memory allocation. Allowing SK_SKB programs to set this field creates a conflict with future code optimizations, such as "gifting" the skb to the egress path instead of creating a new skb and doing a memcpy. Because we do not have a released version of SK_SKB yet lets just remove it for now. A more appropriate scratch pad to use at the socket layer is dev_scratch, but lets add that in future kernels when needed. Signed-off-by: John Fastabend Acked-by: Daniel Borkmann Acked-by: Alexei Starovoitov Signed-off-by: David S. Miller --- tools/testing/selftests/bpf/test_verifier.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) (limited to 'tools') diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c index 3c7d3a45a3c5..50e15cedbb7f 100644 --- a/tools/testing/selftests/bpf/test_verifier.c +++ b/tools/testing/selftests/bpf/test_verifier.c @@ -1130,15 +1130,27 @@ static struct bpf_test tests[] = { .errstr = "invalid bpf_context access", }, { - "check skb->mark is writeable by SK_SKB", + "invalid access of skb->mark for SK_SKB", + .insns = { + BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1, + offsetof(struct __sk_buff, mark)), + BPF_EXIT_INSN(), + }, + .result = REJECT, + .prog_type = BPF_PROG_TYPE_SK_SKB, + .errstr = "invalid bpf_context access", + }, + { + "check skb->mark is not writeable by SK_SKB", .insns = { BPF_MOV64_IMM(BPF_REG_0, 0), BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_0, offsetof(struct __sk_buff, mark)), BPF_EXIT_INSN(), }, - .result = ACCEPT, + .result = REJECT, .prog_type = BPF_PROG_TYPE_SK_SKB, + .errstr = "invalid bpf_context access", }, { "check skb->tc_index is writeable by SK_SKB", -- cgit