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| author | John Fastabend <john.fastabend@gmail.com> | 2017-10-18 07:10:58 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-10-20 13:01:29 +0100 |
| commit | f7e9cb1ecb6d922584abff16db07930162c57155 (patch) | |
| tree | 3686d4b38db981a9289725f9c9aed66ed59b7607 | |
| parent | 34f79502bbcfab659b8729da68b5e387f96eb4c1 (diff) | |
| download | linux-f7e9cb1ecb6d922584abff16db07930162c57155.tar.bz2 | |
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 <john.fastabend@gmail.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/core/filter.c | 2 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/test_verifier.c | 16 |
2 files changed, 15 insertions, 3 deletions
diff --git a/net/core/filter.c b/net/core/filter.c index ca1ba0bbfbc2..aa0265997f93 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -3684,7 +3684,6 @@ static bool sk_skb_is_valid_access(int off, int size, { if (type == BPF_WRITE) { switch (off) { - case bpf_ctx_range(struct __sk_buff, mark): case bpf_ctx_range(struct __sk_buff, tc_index): case bpf_ctx_range(struct __sk_buff, priority): break; @@ -3694,6 +3693,7 @@ static bool sk_skb_is_valid_access(int off, int size, } switch (off) { + case bpf_ctx_range(struct __sk_buff, mark): case bpf_ctx_range(struct __sk_buff, tc_classid): return false; case bpf_ctx_range(struct __sk_buff, data): 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", |