selftests/bpf: Negative test case for ref_obj_id in args

This patch adds a test case, as shown below, for the verifier error
"more than one arg with ref_obj_id".

    0: (b7) r2 = 20
    1: (b7) r3 = 0
    2: (18) r1 = 0xffff92cee3cbc600
    4: (85) call bpf_ringbuf_reserve#131
    5: (55) if r0 == 0x0 goto pc+3
    6: (bf) r1 = r0
    7: (bf) r2 = r0
    8: (85) call bpf_tcp_raw_gen_syncookie_ipv4#204
    9: (95) exit

This error is currently incorrectly reported as a verifier bug, with a
warning. The next patch in this series will address that.

Signed-off-by: Paul Chaignon <paul.chaignon@gmail.com>
Link: https://lore.kernel.org/r/3ba78e6cda47ccafd6ea70dadbc718d020154664.1751463262.git.paul.chaignon@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>

diff --git a/tools/testing/selftests/bpf/verifier/calls.c b/tools/testing/selftests/bpf/verifier/calls.c
index 18596ae0b0c19fdbb6705a807bc919b9fb352d4a..f3492efc88346ecb6f08289769fb4f7ad5a131ef 100644 (file)
--- a/tools/testing/selftests/bpf/verifier/calls.c
+++ b/tools/testing/selftests/bpf/verifier/calls.c
@@ -2409,3 +2409,27 @@
        .errstr_unpriv = "",
        .prog_type = BPF_PROG_TYPE_CGROUP_SKB,
 },
+{
+       "calls: several args with ref_obj_id",
+       .insns = {
+       /* Reserve at least sizeof(struct iphdr) bytes in the ring buffer.
+        * With a smaller size, the verifier would reject the call to
+        * bpf_tcp_raw_gen_syncookie_ipv4 before we can reach the
+        * ref_obj_id error.
+        */
+       BPF_MOV64_IMM(BPF_REG_2, 20),
+       BPF_MOV64_IMM(BPF_REG_3, 0),
+       BPF_LD_MAP_FD(BPF_REG_1, 0),
+       BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_ringbuf_reserve),
+       /* if r0 == 0 goto <exit> */
+       BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 3),
+       BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+       BPF_MOV64_REG(BPF_REG_2, BPF_REG_0),
+       BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_tcp_raw_gen_syncookie_ipv4),
+       BPF_EXIT_INSN(),
+       },
+       .fixup_map_ringbuf = { 2 },
+       .result = REJECT,
+       .errstr = "more than one arg with ref_obj_id",
+       .prog_type = BPF_PROG_TYPE_SCHED_CLS,
+},