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| author | Daniel Borkmann <daniel@iogearbox.net> | 2018-01-17 01:30:10 +0300 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2018-01-17 02:04:58 +0300 |
| commit | f37a8cb84cce18762e8f86a70bd6a49a66ab964c (patch) | |
| tree | d6440b185e4d4810624fb59163ff419cd1a28ca4 /tools | |
| parent | a2284d912bfc865cdca4c00488e08a3550f9a405 (diff) | |
| download | linux-f37a8cb84cce18762e8f86a70bd6a49a66ab964c.tar.xz | |
bpf: reject stores into ctx via st and xadd
Alexei found that verifier does not reject stores into context
via BPF_ST instead of BPF_STX. And while looking at it, we
also should not allow XADD variant of BPF_STX.
The context rewriter is only assuming either BPF_LDX_MEM- or
BPF_STX_MEM-type operations, thus reject anything other than
that so that assumptions in the rewriter properly hold. Add
test cases as well for BPF selftests.
Fixes: d691f9e8d440 ("bpf: allow programs to write to certain skb fields")
Reported-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'tools')
| -rw-r--r-- | tools/testing/selftests/bpf/test_verifier.c | 29 |
1 files changed, 27 insertions, 2 deletions
diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c index 6bafa5456568..67e7c41674d2 100644 --- a/tools/testing/selftests/bpf/test_verifier.c +++ b/tools/testing/selftests/bpf/test_verifier.c @@ -2593,6 +2593,29 @@ static struct bpf_test tests[] = { .prog_type = BPF_PROG_TYPE_SCHED_CLS, }, { + "context stores via ST", + .insns = { + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_ST_MEM(BPF_DW, BPF_REG_1, offsetof(struct __sk_buff, mark), 0), + BPF_EXIT_INSN(), + }, + .errstr = "BPF_ST stores into R1 context is not allowed", + .result = REJECT, + .prog_type = BPF_PROG_TYPE_SCHED_CLS, + }, + { + "context stores via XADD", + .insns = { + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_RAW_INSN(BPF_STX | BPF_XADD | BPF_W, BPF_REG_1, + BPF_REG_0, offsetof(struct __sk_buff, mark), 0), + BPF_EXIT_INSN(), + }, + .errstr = "BPF_XADD stores into R1 context is not allowed", + .result = REJECT, + .prog_type = BPF_PROG_TYPE_SCHED_CLS, + }, + { "direct packet access: test1", .insns = { BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, @@ -4312,7 +4335,8 @@ static struct bpf_test tests[] = { .fixup_map1 = { 2 }, .errstr_unpriv = "R2 leaks addr into mem", .result_unpriv = REJECT, - .result = ACCEPT, + .result = REJECT, + .errstr = "BPF_XADD stores into R1 context is not allowed", }, { "leak pointer into ctx 2", @@ -4326,7 +4350,8 @@ static struct bpf_test tests[] = { }, .errstr_unpriv = "R10 leaks addr into mem", .result_unpriv = REJECT, - .result = ACCEPT, + .result = REJECT, + .errstr = "BPF_XADD stores into R1 context is not allowed", }, { "leak pointer into ctx 3", |