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authorDaniel Borkmann <daniel@iogearbox.net>2018-01-16 23:30:10 +0100
committerAlexei Starovoitov <ast@kernel.org>2018-01-16 15:04:58 -0800
commitf37a8cb84cce18762e8f86a70bd6a49a66ab964c (patch)
treed6440b185e4d4810624fb59163ff419cd1a28ca4 /tools/testing
parenta2284d912bfc865cdca4c00488e08a3550f9a405 (diff)
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/testing')
-rw-r--r--tools/testing/selftests/bpf/test_verifier.c29
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",