[PATCH bpf-next v1 10/13] selftests/bpf: Add dynptr pruning tests

Kumar Kartikeya Dwivedi
2022-10-18T14:00:19Z

Add verifier tests that verify the new pruning behavior for STACK_DYNPTR
slots, and ensure that state equivalence takes into account changes to
the old and current verifier state correctly.

Without the prior fixes, both of these bugs trigger with unprivileged
BPF mode.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
tools/testing/selftests/bpf/verifier/dynptr.c | 90 +++++++++++++++++++
1 file changed, 90 insertions(+)
create mode 100644 tools/testing/selftests/bpf/verifier/dynptr.c

diff --git a/tools/testing/selftests/bpf/verifier/dynptr.c b/tools/testing/selftests/bpf/verifier/dynptr.c
new file mode 100644
index 000000000000..798f4f7e0c57
--- /dev/null
+++ b/tools/testing/selftests/bpf/verifier/dynptr.c
@@ -0,0 +1,90 @@
+{
+ "dynptr: rewrite dynptr slot",
+ .insns = {
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_LD_MAP_FD(BPF_REG_6, 0),
+ BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
+ BPF_MOV64_IMM(BPF_REG_2, 8),
+ BPF_MOV64_IMM(BPF_REG_3, 0),
+ BPF_MOV64_REG(BPF_REG_4, BPF_REG_10),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_4, -16),
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_ringbuf_reserve_dynptr),
+ BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 1),
+ BPF_JMP_IMM(BPF_JA, 0, 0, 1),
+ BPF_ST_MEM(BPF_DW, BPF_REG_10, -16, 0xeB9F),
+ BPF_MOV64_REG(BPF_REG_1, BPF_REG_10),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -16),
+ BPF_MOV64_IMM(BPF_REG_2, 0),
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_ringbuf_discard_dynptr),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .fixup_map_ringbuf = { 1 },
+ .result_unpriv = REJECT,
+ .errstr_unpriv = "unknown func bpf_ringbuf_reserve_dynptr#198",
+ .result = REJECT,
+ .errstr = "arg 1 is an unacquired reference",
+},
+{
+ "dynptr: type confusion",
+ .insns = {
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_LD_MAP_FD(BPF_REG_6, 0),
+ BPF_LD_MAP_FD(BPF_REG_7, 0),
+ BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
+ BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
+ BPF_ST_MEM(BPF_DW, BPF_REG_2, 0, 0),
+ BPF_MOV64_REG(BPF_REG_3, BPF_REG_10),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_3, -24),
+ BPF_ST_MEM(BPF_DW, BPF_REG_10, -16, 0xeB9FeB9F),
+ BPF_ST_MEM(BPF_DW, BPF_REG_10, -24, 0xeB9FeB9F),
+ BPF_MOV64_IMM(BPF_REG_4, 0),
+ BPF_MOV64_REG(BPF_REG_8, BPF_REG_2),
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_update_elem),
+ BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
+ BPF_MOV64_REG(BPF_REG_2, BPF_REG_8),
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
+ BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 1),
+ BPF_EXIT_INSN(),
+ BPF_MOV64_REG(BPF_REG_8, BPF_REG_0),
+ BPF_MOV64_REG(BPF_REG_1, BPF_REG_7),
+ BPF_MOV64_IMM(BPF_REG_2, 8),
+ BPF_MOV64_IMM(BPF_REG_3, 0),
+ BPF_MOV64_REG(BPF_REG_4, BPF_REG_10),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_4, -16),
+ BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_0, 0),
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_ringbuf_reserve_dynptr),
+ BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 8),
+ /* pad with insns to trigger add_new_state heuristic for straight line path */
+ BPF_MOV64_REG(BPF_REG_8, BPF_REG_8),
+ BPF_MOV64_REG(BPF_REG_8, BPF_REG_8),
+ BPF_MOV64_REG(BPF_REG_8, BPF_REG_8),
+ BPF_MOV64_REG(BPF_REG_8, BPF_REG_8),
+ BPF_MOV64_REG(BPF_REG_8, BPF_REG_8),
+ BPF_MOV64_REG(BPF_REG_8, BPF_REG_8),
+ BPF_MOV64_REG(BPF_REG_8, BPF_REG_8),
+ BPF_JMP_IMM(BPF_JA, 0, 0, 9),
+ BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
+ BPF_ST_MEM(BPF_DW, BPF_REG_10, -16, 0),
+ BPF_MOV64_REG(BPF_REG_1, BPF_REG_8),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, 8),
+ BPF_MOV64_IMM(BPF_REG_2, 0),
+ BPF_MOV64_IMM(BPF_REG_3, 0),
+ BPF_MOV64_REG(BPF_REG_4, BPF_REG_10),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_4, -16),
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_dynptr_from_mem),
+ BPF_MOV64_REG(BPF_REG_1, BPF_REG_10),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -16),
+ BPF_MOV64_IMM(BPF_REG_2, 0),
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_ringbuf_discard_dynptr),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .fixup_map_hash_16b = { 1 },
+ .fixup_map_ringbuf = { 3 },
+ .result_unpriv = REJECT,
+ .errstr_unpriv = "unknown func bpf_ringbuf_reserve_dynptr#198",
+ .result = REJECT,
+ .errstr = "arg 1 is an unacquired reference",
+},
--
2.38.0