[PATCH 5.15 019/177] bpf, selftests: Update test case for atomic cmpxchg on r0 with pointer

Greg Kroah-Hartman
2021-12-20T14:56:33Z

From: Daniel Borkmann <daniel@iogearbox.net>

commit e523102cb719cbad1673b6aa2a4d5c1fa6f13799 upstream.

Fix up unprivileged test case results for 'Dest pointer in r0' verifier tests
given they now need to reject R0 containing a pointer value, and add a couple
of new related ones with 32bit cmpxchg as well.

root@foo:~/bpf/tools/testing/selftests/bpf# ./test_verifier
#0/u invalid and of negative number OK
#0/p invalid and of negative number OK
[...]
#1268/p XDP pkt read, pkt_meta' <= pkt_data, bad access 1 OK
#1269/p XDP pkt read, pkt_meta' <= pkt_data, bad access 2 OK
#1270/p XDP pkt read, pkt_data <= pkt_meta', good access OK
#1271/p XDP pkt read, pkt_data <= pkt_meta', bad access 1 OK
#1272/p XDP pkt read, pkt_data <= pkt_meta', bad access 2 OK
Summary: 1900 PASSED, 0 SKIPPED, 0 FAILED

Acked-by: Brendan Jackman <jackmanb@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
tools/testing/selftests/bpf/verifier/atomic_cmpxchg.c | 67 +++++++++++++++++-
1 file changed, 65 insertions(+), 2 deletions(-)

--- a/tools/testing/selftests/bpf/verifier/atomic_cmpxchg.c
+++ b/tools/testing/selftests/bpf/verifier/atomic_cmpxchg.c
@@ -71,6 +71,8 @@
BPF_EXIT_INSN(),
},
.result = ACCEPT,
+ .result_unpriv = REJECT,
+ .errstr_unpriv = "R0 leaks addr into mem",
},
{
"Can't use cmpxchg on uninit src reg",
@@ -119,7 +121,7 @@
},
.result = ACCEPT,
.result_unpriv = REJECT,
- .errstr_unpriv = "leaking pointer from stack off -8",
+ .errstr_unpriv = "R0 leaks addr into mem",
},
{
"Dest pointer in r0 - succeed, check 2",
@@ -140,5 +142,66 @@
},
.result = ACCEPT,
.result_unpriv = REJECT,
- .errstr_unpriv = "R5 leaks addr into mem",
+ .errstr_unpriv = "R0 leaks addr into mem",
+},
+{
+ "Dest pointer in r0 - succeed, check 3",
+ .insns = {
+ /* r0 = &val */
+ BPF_MOV64_REG(BPF_REG_0, BPF_REG_10),
+ /* val = r0; */
+ BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_0, -8),
+ /* r5 = &val */
+ BPF_MOV64_REG(BPF_REG_5, BPF_REG_10),
+ /* r0 = atomic_cmpxchg(&val, r0, r5); */
+ BPF_ATOMIC_OP(BPF_W, BPF_CMPXCHG, BPF_REG_10, BPF_REG_5, -8),
+ /* exit(0); */
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .result = REJECT,
+ .errstr = "invalid size of register fill",
+ .errstr_unpriv = "R0 leaks addr into mem",
+},
+{
+ "Dest pointer in r0 - succeed, check 4",
+ .insns = {
+ /* r0 = &val */
+ BPF_MOV32_REG(BPF_REG_0, BPF_REG_10),
+ /* val = r0; */
+ BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_0, -8),
+ /* r5 = &val */
+ BPF_MOV32_REG(BPF_REG_5, BPF_REG_10),
+ /* r0 = atomic_cmpxchg(&val, r0, r5); */
+ BPF_ATOMIC_OP(BPF_W, BPF_CMPXCHG, BPF_REG_10, BPF_REG_5, -8),
+ /* r1 = *r10 */
+ BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_10, -8),
+ /* exit(0); */
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .result = ACCEPT,
+ .result_unpriv = REJECT,
+ .errstr_unpriv = "R10 partial copy of pointer",
+},
+{
+ "Dest pointer in r0 - succeed, check 5",
+ .insns = {
+ /* r0 = &val */
+ BPF_MOV32_REG(BPF_REG_0, BPF_REG_10),
+ /* val = r0; */
+ BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_0, -8),
+ /* r5 = &val */
+ BPF_MOV32_REG(BPF_REG_5, BPF_REG_10),
+ /* r0 = atomic_cmpxchg(&val, r0, r5); */
+ BPF_ATOMIC_OP(BPF_W, BPF_CMPXCHG, BPF_REG_10, BPF_REG_5, -8),
+ /* r1 = *r0 */
+ BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_0, -8),
+ /* exit(0); */
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .result = REJECT,
+ .errstr = "R0 invalid mem access",
+ .errstr_unpriv = "R10 partial copy of pointer",
},